drivers/char/pcmcia/synclink_cs.c

/*
 * linux/drivers/char/pcmcia/synclink_cs.c
 *
 * $Id: synclink_cs.c,v 4.34 2005/09/08 13:20:54 paulkf Exp $
 *
 * Device driver for Microgate SyncLink PC Card
 * multiprotocol serial adapter.
 *
 * written by Paul Fulghum for Microgate Corporation
 * paulkf@microgate.com
 *
 * Microgate and SyncLink are trademarks of Microgate Corporation
 *
 * This code is released under the GNU General Public License (GPL)
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#define VERSION(ver,rel,seq) (((ver)<<16) | ((rel)<<8) | (seq))
#if defined(__i386__)
#  define BREAKPOINT() asm("   int $3");
#else
#  define BREAKPOINT() { }
#endif

#define MAX_DEVICE_COUNT 4

#include <linux/module.h>
#include <linux/errno.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/timer.h>
#include <linux/time.h>
#include <linux/interrupt.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/serial.h>
#include <linux/major.h>
#include <linux/string.h>
#include <linux/fcntl.h>
#include <linux/ptrace.h>
#include <linux/ioport.h>
#include <linux/mm.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/netdevice.h>
#include <linux/vmalloc.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/ioctl.h>
#include <linux/synclink.h>

#include <asm/system.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <asm/dma.h>
#include <linux/bitops.h>
#include <asm/types.h>
#include <linux/termios.h>
#include <linux/workqueue.h>
#include <linux/hdlc.h>

#include <pcmcia/cs.h>
#include <pcmcia/cistpl.h>
#include <pcmcia/cisreg.h>
#include <pcmcia/ds.h>

#if defined(CONFIG_HDLC) || (defined(CONFIG_HDLC_MODULE) && defined(CONFIG_SYNCLINK_CS_MODULE))
#define SYNCLINK_GENERIC_HDLC 1
#else
#define SYNCLINK_GENERIC_HDLC 0
#endif

#define GET_USER(error,value,addr) error = get_user(value,addr)
#define COPY_FROM_USER(error,dest,src,size) error = copy_from_user(dest,src,size) ? -EFAULT : 0
#define PUT_USER(error,value,addr) error = put_user(value,addr)
#define COPY_TO_USER(error,dest,src,size) error = copy_to_user(dest,src,size) ? -EFAULT : 0

#include <asm/uaccess.h>

static MGSL_PARAMS default_params = {
	MGSL_MODE_HDLC,			/* unsigned long mode */
	0,				/* unsigned char loopback; */
	HDLC_FLAG_UNDERRUN_ABORT15,	/* unsigned short flags; */
	HDLC_ENCODING_NRZI_SPACE,	/* unsigned char encoding; */
	0,				/* unsigned long clock_speed; */
	0xff,				/* unsigned char addr_filter; */
	HDLC_CRC_16_CCITT,		/* unsigned short crc_type; */
	HDLC_PREAMBLE_LENGTH_8BITS,	/* unsigned char preamble_length; */
	HDLC_PREAMBLE_PATTERN_NONE,	/* unsigned char preamble; */
	9600,				/* unsigned long data_rate; */
	8,				/* unsigned char data_bits; */
	1,				/* unsigned char stop_bits; */
	ASYNC_PARITY_NONE		/* unsigned char parity; */
};

typedef struct
{
	int count;
	unsigned char status;
	char data[1];
} RXBUF;

/* The queue of BH actions to be performed */

#define BH_RECEIVE  1
#define BH_TRANSMIT 2
#define BH_STATUS   4

#define IO_PIN_SHUTDOWN_LIMIT 100

#define RELEVANT_IFLAG(iflag) (iflag & (IGNBRK|BRKINT|IGNPAR|PARMRK|INPCK))

struct _input_signal_events {
	int	ri_up;
	int	ri_down;
	int	dsr_up;
	int	dsr_down;
	int	dcd_up;
	int	dcd_down;
	int	cts_up;
	int	cts_down;
};


/*
 * Device instance data structure
 */

typedef struct _mgslpc_info {
	struct tty_port		port;
	void *if_ptr;	/* General purpose pointer (used by SPPP) */
	int			magic;
	int			line;

	struct mgsl_icount	icount;

	int			timeout;
	int			x_char;		/* xon/xoff character */
	unsigned char		read_status_mask;
	unsigned char		ignore_status_mask;

	unsigned char *tx_buf;
	int            tx_put;
	int            tx_get;
	int            tx_count;

	/* circular list of fixed length rx buffers */

	unsigned char  *rx_buf;        /* memory allocated for all rx buffers */
	int            rx_buf_total_size; /* size of memory allocated for rx buffers */
	int            rx_put;         /* index of next empty rx buffer */
	int            rx_get;         /* index of next full rx buffer */
	int            rx_buf_size;    /* size in bytes of single rx buffer */
	int            rx_buf_count;   /* total number of rx buffers */
	int            rx_frame_count; /* number of full rx buffers */

	wait_queue_head_t	status_event_wait_q;
	wait_queue_head_t	event_wait_q;
	struct timer_list	tx_timer;	/* HDLC transmit timeout timer */
	struct _mgslpc_info	*next_device;	/* device list link */

	unsigned short imra_value;
	unsigned short imrb_value;
	unsigned char  pim_value;

	spinlock_t lock;
	struct work_struct task;		/* task structure for scheduling bh */

	u32 max_frame_size;

	u32 pending_bh;

	bool bh_running;
	bool bh_requested;

	int dcd_chkcount; /* check counts to prevent */
	int cts_chkcount; /* too many IRQs if a signal */
	int dsr_chkcount; /* is floating */
	int ri_chkcount;

	bool rx_enabled;
	bool rx_overflow;

	bool tx_enabled;
	bool tx_active;
	bool tx_aborting;
	u32 idle_mode;

	int if_mode; /* serial interface selection (RS-232, v.35 etc) */

	char device_name[25];		/* device instance name */

	unsigned int io_base;	/* base I/O address of adapter */
	unsigned int irq_level;

	MGSL_PARAMS params;		/* communications parameters */

	unsigned char serial_signals;	/* current serial signal states */

	bool irq_occurred;		/* for diagnostics use */
	char testing_irq;
	unsigned int init_error;	/* startup error (DIAGS)	*/

	char flag_buf[MAX_ASYNC_BUFFER_SIZE];
	bool drop_rts_on_tx_done;

	struct	_input_signal_events	input_signal_events;

	/* PCMCIA support */
	struct pcmcia_device	*p_dev;
	int		      stop;

	/* SPPP/Cisco HDLC device parts */
	int netcount;
	spinlock_t netlock;

#if SYNCLINK_GENERIC_HDLC
	struct net_device *netdev;
#endif

} MGSLPC_INFO;

#define MGSLPC_MAGIC 0x5402

/*
 * The size of the serial xmit buffer is 1 page, or 4096 bytes
 */
#define TXBUFSIZE 4096


#define CHA     0x00   /* channel A offset */
#define CHB     0x40   /* channel B offset */

/*
 *  FIXME: PPC has PVR defined in asm/reg.h.  For now we just undef it.
 */
#undef PVR

#define RXFIFO  0
#define TXFIFO  0
#define STAR    0x20
#define CMDR    0x20
#define RSTA    0x21
#define PRE     0x21
#define MODE    0x22
#define TIMR    0x23
#define XAD1    0x24
#define XAD2    0x25
#define RAH1    0x26
#define RAH2    0x27
#define DAFO    0x27
#define RAL1    0x28
#define RFC     0x28
#define RHCR    0x29
#define RAL2    0x29
#define RBCL    0x2a
#define XBCL    0x2a
#define RBCH    0x2b
#define XBCH    0x2b
#define CCR0    0x2c
#define CCR1    0x2d
#define CCR2    0x2e
#define CCR3    0x2f
#define VSTR    0x34
#define BGR     0x34
#define RLCR    0x35
#define AML     0x36
#define AMH     0x37
#define GIS     0x38
#define IVA     0x38
#define IPC     0x39
#define ISR     0x3a
#define IMR     0x3a
#define PVR     0x3c
#define PIS     0x3d
#define PIM     0x3d
#define PCR     0x3e
#define CCR4    0x3f

// IMR/ISR

#define IRQ_BREAK_ON    BIT15   // rx break detected
#define IRQ_DATAOVERRUN BIT14	// receive data overflow
#define IRQ_ALLSENT     BIT13	// all sent
#define IRQ_UNDERRUN    BIT12	// transmit data underrun
#define IRQ_TIMER       BIT11	// timer interrupt
#define IRQ_CTS         BIT10	// CTS status change
#define IRQ_TXREPEAT    BIT9	// tx message repeat
#define IRQ_TXFIFO      BIT8	// transmit pool ready
#define IRQ_RXEOM       BIT7	// receive message end
#define IRQ_EXITHUNT    BIT6	// receive frame start
#define IRQ_RXTIME      BIT6    // rx char timeout
#define IRQ_DCD         BIT2	// carrier detect status change
#define IRQ_OVERRUN     BIT1	// receive frame overflow
#define IRQ_RXFIFO      BIT0	// receive pool full

// STAR

#define XFW   BIT6		// transmit FIFO write enable
#define CEC   BIT2		// command executing
#define CTS   BIT1		// CTS state

#define PVR_DTR      BIT0
#define PVR_DSR      BIT1
#define PVR_RI       BIT2
#define PVR_AUTOCTS  BIT3
#define PVR_RS232    0x20   /* 0010b */
#define PVR_V35      0xe0   /* 1110b */
#define PVR_RS422    0x40   /* 0100b */

/* Register access functions */

#define write_reg(info, reg, val) outb((val),(info)->io_base + (reg))
#define read_reg(info, reg) inb((info)->io_base + (reg))

#define read_reg16(info, reg) inw((info)->io_base + (reg))
#define write_reg16(info, reg, val) outw((val), (info)->io_base + (reg))

#define set_reg_bits(info, reg, mask) \
    write_reg(info, (reg), \
		 (unsigned char) (read_reg(info, (reg)) | (mask)))
#define clear_reg_bits(info, reg, mask) \
    write_reg(info, (reg), \
		 (unsigned char) (read_reg(info, (reg)) & ~(mask)))
/*
 * interrupt enable/disable routines
 */
static void irq_disable(MGSLPC_INFO *info, unsigned char channel, unsigned short mask)
{
	if (channel == CHA) {
		info->imra_value |= mask;
		write_reg16(info, CHA + IMR, info->imra_value);
	} else {
		info->imrb_value |= mask;
		write_reg16(info, CHB + IMR, info->imrb_value);
	}
}
static void irq_enable(MGSLPC_INFO *info, unsigned char channel, unsigned short mask)
{
	if (channel == CHA) {
		info->imra_value &= ~mask;
		write_reg16(info, CHA + IMR, info->imra_value);
	} else {
		info->imrb_value &= ~mask;
		write_reg16(info, CHB + IMR, info->imrb_value);
	}
}

#define port_irq_disable(info, mask) \
  { info->pim_value |= (mask); write_reg(info, PIM, info->pim_value); }

#define port_irq_enable(info, mask) \
  { info->pim_value &= ~(mask); write_reg(info, PIM, info->pim_value); }

static void rx_start(MGSLPC_INFO *info);
static void rx_stop(MGSLPC_INFO *info);

static void tx_start(MGSLPC_INFO *info, struct tty_struct *tty);
static void tx_stop(MGSLPC_INFO *info);
static void tx_set_idle(MGSLPC_INFO *info);

static void get_signals(MGSLPC_INFO *info);
static void set_signals(MGSLPC_INFO *info);

static void reset_device(MGSLPC_INFO *info);

static void hdlc_mode(MGSLPC_INFO *info);
static void async_mode(MGSLPC_INFO *info);

static void tx_timeout(unsigned long context);

static int carrier_raised(struct tty_port *port);
static void dtr_rts(struct tty_port *port, int onoff);

#if SYNCLINK_GENERIC_HDLC
#define dev_to_port(D) (dev_to_hdlc(D)->priv)
static void hdlcdev_tx_done(MGSLPC_INFO *info);
static void hdlcdev_rx(MGSLPC_INFO *info, char *buf, int size);
static int  hdlcdev_init(MGSLPC_INFO *info);
static void hdlcdev_exit(MGSLPC_INFO *info);
#endif

static void trace_block(MGSLPC_INFO *info,const char* data, int count, int xmit);

static bool register_test(MGSLPC_INFO *info);
static bool irq_test(MGSLPC_INFO *info);
static int adapter_test(MGSLPC_INFO *info);

static int claim_resources(MGSLPC_INFO *info);
static void release_resources(MGSLPC_INFO *info);
static void mgslpc_add_device(MGSLPC_INFO *info);
static void mgslpc_remove_device(MGSLPC_INFO *info);

static bool rx_get_frame(MGSLPC_INFO *info, struct tty_struct *tty);
static void rx_reset_buffers(MGSLPC_INFO *info);
static int  rx_alloc_buffers(MGSLPC_INFO *info);
static void rx_free_buffers(MGSLPC_INFO *info);

static irqreturn_t mgslpc_isr(int irq, void *dev_id);

/*
 * Bottom half interrupt handlers
 */
static void bh_handler(struct work_struct *work);
static void bh_transmit(MGSLPC_INFO *info, struct tty_struct *tty);
static void bh_status(MGSLPC_INFO *info);

/*
 * ioctl handlers
 */
static int tiocmget(struct tty_struct *tty, struct file *file);
static int tiocmset(struct tty_struct *tty, struct file *file,
		    unsigned int set, unsigned int clear);
static int get_stats(MGSLPC_INFO *info, struct mgsl_icount __user *user_icount);
static int get_params(MGSLPC_INFO *info, MGSL_PARAMS __user *user_params);
static int set_params(MGSLPC_INFO *info, MGSL_PARAMS __user *new_params, struct tty_struct *tty);
static int get_txidle(MGSLPC_INFO *info, int __user *idle_mode);
static int set_txidle(MGSLPC_INFO *info, int idle_mode);
static int set_txenable(MGSLPC_INFO *info, int enable, struct tty_struct *tty);
static int tx_abort(MGSLPC_INFO *info);
static int set_rxenable(MGSLPC_INFO *info, int enable);
static int wait_events(MGSLPC_INFO *info, int __user *mask);

static MGSLPC_INFO *mgslpc_device_list = NULL;
static int mgslpc_device_count = 0;

/*
 * Set this param to non-zero to load eax with the
 * .text section address and breakpoint on module load.
 * This is useful for use with gdb and add-symbol-file command.
 */
static int break_on_load=0;

/*
 * Driver major number, defaults to zero to get auto
 * assigned major number. May be forced as module parameter.
 */
static int ttymajor=0;

static int debug_level = 0;
static int maxframe[MAX_DEVICE_COUNT] = {0,};

module_param(break_on_load, bool, 0);
module_param(ttymajor, int, 0);
module_param(debug_level, int, 0);
module_param_array(maxframe, int, NULL, 0);

MODULE_LICENSE("GPL");

static char *driver_name = "SyncLink PC Card driver";
static char *driver_version = "$Revision: 4.34 $";

static struct tty_driver *serial_driver;

/* number of characters left in xmit buffer before we ask for more */
#define WAKEUP_CHARS 256

static void mgslpc_change_params(MGSLPC_INFO *info, struct tty_struct *tty);
static void mgslpc_wait_until_sent(struct tty_struct *tty, int timeout);

/* PCMCIA prototypes */

static int mgslpc_config(struct pcmcia_device *link);
static void mgslpc_release(u_long arg);
static void mgslpc_detach(struct pcmcia_device *p_dev);

/*
 * 1st function defined in .text section. Calling this function in
 * init_module() followed by a breakpoint allows a remote debugger
 * (gdb) to get the .text address for the add-symbol-file command.
 * This allows remote debugging of dynamically loadable modules.
 */
static void* mgslpc_get_text_ptr(void)
{
	return mgslpc_get_text_ptr;
}

/**
 * line discipline callback wrappers
 *
 * The wrappers maintain line discipline references
 * while calling into the line discipline.
 *
 * ldisc_receive_buf  - pass receive data to line discipline
 */

static void ldisc_receive_buf(struct tty_struct *tty,
			      const __u8 *data, char *flags, int count)
{
	struct tty_ldisc *ld;
	if (!tty)
		return;
	ld = tty_ldisc_ref(tty);
	if (ld) {
		if (ld->ops->receive_buf)
			ld->ops->receive_buf(tty, data, flags, count);
		tty_ldisc_deref(ld);
	}
}

static const struct tty_port_operations mgslpc_port_ops = {
	.carrier_raised = carrier_raised,
	.dtr_rts = dtr_rts
};

static int mgslpc_probe(struct pcmcia_device *link)
{
    MGSLPC_INFO *info;
    int ret;

    if (debug_level >= DEBUG_LEVEL_INFO)
	    printk("mgslpc_attach\n");

    info = kzalloc(sizeof(MGSLPC_INFO), GFP_KERNEL);
    if (!info) {
	    printk("Error can't allocate device instance data\n");
	    return -ENOMEM;
    }

    info->magic = MGSLPC_MAGIC;
    tty_port_init(&info->port);
    info->port.ops = &mgslpc_port_ops;
    INIT_WORK(&info->task, bh_handler);
    info->max_frame_size = 4096;
    info->port.close_delay = 5*HZ/10;
    info->port.closing_wait = 30*HZ;
    init_waitqueue_head(&info->status_event_wait_q);
    init_waitqueue_head(&info->event_wait_q);
    spin_lock_init(&info->lock);
    spin_lock_init(&info->netlock);
    memcpy(&info->params,&default_params,sizeof(MGSL_PARAMS));
    info->idle_mode = HDLC_TXIDLE_FLAGS;
    info->imra_value = 0xffff;
    info->imrb_value = 0xffff;
    info->pim_value = 0xff;

    info->p_dev = link;
    link->priv = info;

    /* Initialize the struct pcmcia_device structure */

    link->conf.Attributes = 0;
    link->conf.IntType = INT_MEMORY_AND_IO;

    ret = mgslpc_config(link);
    if (ret)
	    return ret;

    mgslpc_add_device(info);

    return 0;
}

/* Card has been inserted.
 */

static int mgslpc_ioprobe(struct pcmcia_device *p_dev,
			  cistpl_cftable_entry_t *cfg,
			  cistpl_cftable_entry_t *dflt,
			  unsigned int vcc,
			  void *priv_data)
{
	if (!cfg->io.nwin)
		return -ENODEV;

	p_dev->resource[0]->start = cfg->io.win[0].base;
	p_dev->resource[0]->end = cfg->io.win[0].len;
	p_dev->resource[0]->flags |= pcmcia_io_cfg_data_width(cfg->io.flags);
	p_dev->io_lines = cfg->io.flags & CISTPL_IO_LINES_MASK;

	return pcmcia_request_io(p_dev);
}

static int mgslpc_config(struct pcmcia_device *link)
{
    MGSLPC_INFO *info = link->priv;
    int ret;

    if (debug_level >= DEBUG_LEVEL_INFO)
	    printk("mgslpc_config(0x%p)\n", link);

    ret = pcmcia_loop_config(link, mgslpc_ioprobe, NULL);
    if (ret != 0)
	    goto failed;

    link->conf.Attributes = CONF_ENABLE_IRQ;
    link->conf.IntType = INT_MEMORY_AND_IO;
    link->conf.ConfigIndex = 8;
    link->conf.Present = PRESENT_OPTION;

    ret = pcmcia_request_irq(link, mgslpc_isr);
    if (ret)
	    goto failed;
    ret = pcmcia_request_configuration(link, &link->conf);
    if (ret)
	    goto failed;

    info->io_base = link->resource[0]->start;
    info->irq_level = link->irq;

    dev_info(&link->dev, "index 0x%02x:",
	    link->conf.ConfigIndex);
    if (link->conf.Attributes & CONF_ENABLE_IRQ)
	    printk(", irq %d", link->irq);
    if (link->resource[0])
	    printk(", io %pR", link->resource[0]);
    printk("\n");
    return 0;

failed:
    mgslpc_release((u_long)link);
    return -ENODEV;
}

/* Card has been removed.
 * Unregister device and release PCMCIA configuration.
 * If device is open, postpone until it is closed.
 */
static void mgslpc_release(u_long arg)
{
	struct pcmcia_device *link = (struct pcmcia_device *)arg;

	if (debug_level >= DEBUG_LEVEL_INFO)
		printk("mgslpc_release(0x%p)\n", link);

	pcmcia_disable_device(link);
}

static void mgslpc_detach(struct pcmcia_device *link)
{
	if (debug_level >= DEBUG_LEVEL_INFO)
		printk("mgslpc_detach(0x%p)\n", link);

	((MGSLPC_INFO *)link->priv)->stop = 1;
	mgslpc_release((u_long)link);

	mgslpc_remove_device((MGSLPC_INFO *)link->priv);
}

static int mgslpc_suspend(struct pcmcia_device *link)
{
	MGSLPC_INFO *info = link->priv;

	info->stop = 1;

	return 0;
}

static int mgslpc_resume(struct pcmcia_device *link)
{
	MGSLPC_INFO *info = link->priv;

	info->stop = 0;

	return 0;
}


static inline bool mgslpc_paranoia_check(MGSLPC_INFO *info,
					char *name, const char *routine)
{
#ifdef MGSLPC_PARANOIA_CHECK
	static const char *badmagic =
		"Warning: bad magic number for mgsl struct (%s) in %s\n";
	static const char *badinfo =
		"Warning: null mgslpc_info for (%s) in %s\n";

	if (!info) {
		printk(badinfo, name, routine);
		return true;
	}
	if (info->magic != MGSLPC_MAGIC) {
		printk(badmagic, name, routine);
		return true;
	}
#else
	if (!info)
		return true;
#endif
	return false;
}


#define CMD_RXFIFO      BIT7	// release current rx FIFO
#define CMD_RXRESET     BIT6	// receiver reset
#define CMD_RXFIFO_READ BIT5
#define CMD_START_TIMER BIT4
#define CMD_TXFIFO      BIT3	// release current tx FIFO
#define CMD_TXEOM       BIT1	// transmit end message
#define CMD_TXRESET     BIT0	// transmit reset

static bool wait_command_complete(MGSLPC_INFO *info, unsigned char channel)
{
	int i = 0;
	/* wait for command completion */
	while (read_reg(info, (unsigned char)(channel+STAR)) & BIT2) {
		udelay(1);
		if (i++ == 1000)
			return false;
	}
	return true;
}

static void issue_command(MGSLPC_INFO *info, unsigned char channel, unsigned char cmd)
{
	wait_command_complete(info, channel);
	write_reg(info, (unsigned char) (channel + CMDR), cmd);
}

static void tx_pause(struct tty_struct *tty)
{
	MGSLPC_INFO *info = (MGSLPC_INFO *)tty->driver_data;
	unsigned long flags;

	if (mgslpc_paranoia_check(info, tty->name, "tx_pause"))
		return;
	if (debug_level >= DEBUG_LEVEL_INFO)
		printk("tx_pause(%s)\n",info->device_name);

	spin_lock_irqsave(&info->lock,flags);
	if (info->tx_enabled)
	 	tx_stop(info);
	spin_unlock_irqrestore(&info->lock,flags);
}

static void tx_release(struct tty_struct *tty)
{
	MGSLPC_INFO *info = (MGSLPC_INFO *)tty->driver_data;
	unsigned long flags;

	if (mgslpc_paranoia_check(info, tty->name, "tx_release"))
		return;
	if (debug_level >= DEBUG_LEVEL_INFO)
		printk("tx_release(%s)\n",info->device_name);

	spin_lock_irqsave(&info->lock,flags);
	if (!info->tx_enabled)
	 	tx_start(info, tty);
	spin_unlock_irqrestore(&info->lock,flags);
}

/* Return next bottom half action to perform.
 * or 0 if nothing to do.
 */
static int bh_action(MGSLPC_INFO *info)
{
	unsigned long flags;
	int rc = 0;

	spin_lock_irqsave(&info->lock,flags);

	if (info->pending_bh & BH_RECEIVE) {
		info->pending_bh &= ~BH_RECEIVE;
		rc = BH_RECEIVE;
	} else if (info->pending_bh & BH_TRANSMIT) {
		info->pending_bh &= ~BH_TRANSMIT;
		rc = BH_TRANSMIT;
	} else if (info->pending_bh & BH_STATUS) {
		info->pending_bh &= ~BH_STATUS;
		rc = BH_STATUS;
	}

	if (!rc) {
		/* Mark BH routine as complete */
		info->bh_running = false;
		info->bh_requested = false;
	}

	spin_unlock_irqrestore(&info->lock,flags);

	return rc;
}

static void bh_handler(struct work_struct *work)
{
	MGSLPC_INFO *info = container_of(work, MGSLPC_INFO, task);
	struct tty_struct *tty;
	int action;

	if (!info)
		return;

	if (debug_level >= DEBUG_LEVEL_BH)
		printk( "%s(%d):bh_handler(%s) entry\n",
			__FILE__,__LINE__,info->device_name);

	info->bh_running = true;
	tty = tty_port_tty_get(&info->port);

	while((action = bh_action(info)) != 0) {

		/* Process work item */
		if ( debug_level >= DEBUG_LEVEL_BH )
			printk( "%s(%d):bh_handler() work item action=%d\n",
				__FILE__,__LINE__,action);

		switch (action) {

		case BH_RECEIVE:
			while(rx_get_frame(info, tty));
			break;
		case BH_TRANSMIT:
			bh_transmit(info, tty);
			break;
		case BH_STATUS:
			bh_status(info);
			break;
		default:
			/* unknown work item ID */
			printk("Unknown work item ID=%08X!\n", action);
			break;
		}
	}

	tty_kref_put(tty);
	if (debug_level >= DEBUG_LEVEL_BH)
		printk( "%s(%d):bh_handler(%s) exit\n",
			__FILE__,__LINE__,info->device_name);
}

static void bh_transmit(MGSLPC_INFO *info, struct tty_struct *tty)
{
	if (debug_level >= DEBUG_LEVEL_BH)
		printk("bh_transmit() entry on %s\n", info->device_name);

	if (tty)
		tty_wakeup(tty);
}

static void bh_status(MGSLPC_INFO *info)
{
	info->ri_chkcount = 0;
	info->dsr_chkcount = 0;
	info->dcd_chkcount = 0;
	info->cts_chkcount = 0;
}

/* eom: non-zero = end of frame */
static void rx_ready_hdlc(MGSLPC_INFO *info, int eom)
{
	unsigned char data[2];
	unsigned char fifo_count, read_count, i;
	RXBUF *buf = (RXBUF*)(info->rx_buf + (info->rx_put * info->rx_buf_size));

	if (debug_level >= DEBUG_LEVEL_ISR)
		printk("%s(%d):rx_ready_hdlc(eom=%d)\n",__FILE__,__LINE__,eom);

	if (!info->rx_enabled)
		return;

	if (info->rx_frame_count >= info->rx_buf_count) {
		/* no more free buffers */
		issue_command(info, CHA, CMD_RXRESET);
		info->pending_bh |= BH_RECEIVE;
		info->rx_overflow = true;
		info->icount.buf_overrun++;
		return;
	}

	if (eom) {
		/* end of frame, get FIFO count from RBCL register */
		if (!(fifo_count = (unsigned char)(read_reg(info, CHA+RBCL) & 0x1f)))
			fifo_count = 32;
	} else
		fifo_count = 32;

	do {
		if (fifo_count == 1) {
			read_count = 1;
			data[0] = read_reg(info, CHA + RXFIFO);
		} else {
			read_count = 2;
			*((unsigned short *) data) = read_reg16(info, CHA + RXFIFO);
		}
		fifo_count -= read_count;
		if (!fifo_count && eom)
			buf->status = data[--read_count];

		for (i = 0; i < read_count; i++) {
			if (buf->count >= info->max_frame_size) {
				/* frame too large, reset receiver and reset current buffer */
				issue_command(info, CHA, CMD_RXRESET);
				buf->count = 0;
				return;
			}
			*(buf->data + buf->count) = data[i];
			buf->count++;
		}
	} while (fifo_count);

	if (eom) {
		info->pending_bh |= BH_RECEIVE;
		info->rx_frame_count++;
		info->rx_put++;
		if (info->rx_put >= info->rx_buf_count)
			info->rx_put = 0;
	}
	issue_command(info, CHA, CMD_RXFIFO);
}

static void rx_ready_async(MGSLPC_INFO *info, int tcd, struct tty_struct *tty)
{
	unsigned char data, status, flag;
	int fifo_count;
	int work = 0;
 	struct mgsl_icount *icount = &info->icount;

	if (tcd) {
		/* early termination, get FIFO count from RBCL register */
		fifo_count = (unsigned char)(read_reg(info, CHA+RBCL) & 0x1f);

		/* Zero fifo count could mean 0 or 32 bytes available.
		 * If BIT5 of STAR is set then at least 1 byte is available.
		 */
		if (!fifo_count && (read_reg(info,CHA+STAR) & BIT5))
			fifo_count = 32;
	} else
		fifo_count = 32;

	tty_buffer_request_room(tty, fifo_count);
	/* Flush received async data to receive data buffer. */
	while (fifo_count) {
		data   = read_reg(info, CHA + RXFIFO);
		status = read_reg(info, CHA + RXFIFO);
		fifo_count -= 2;

		icount->rx++;
		flag = TTY_NORMAL;

		// if no frameing/crc error then save data
		// BIT7:parity error
		// BIT6:framing error

		if (status & (BIT7 + BIT6)) {
			if (status & BIT7)
				icount->parity++;
			else
				icount->frame++;

			/* discard char if tty control flags say so */
			if (status & info->ignore_status_mask)
				continue;

			status &= info->read_status_mask;

			if (status & BIT7)
				flag = TTY_PARITY;
			else if (status & BIT6)
				flag = TTY_FRAME;
		}
		work += tty_insert_flip_char(tty, data, flag);
	}
	issue_command(info, CHA, CMD_RXFIFO);

	if (debug_level >= DEBUG_LEVEL_ISR) {
		printk("%s(%d):rx_ready_async",
			__FILE__,__LINE__);
		printk("%s(%d):rx=%d brk=%d parity=%d frame=%d overrun=%d\n",
			__FILE__,__LINE__,icount->rx,icount->brk,
			icount->parity,icount->frame,icount->overrun);
	}

	if (work)
		tty_flip_buffer_push(tty);
}


static void tx_done(MGSLPC_INFO *info, struct tty_struct *tty)
{
	if (!info->tx_active)
		return;

	info->tx_active = false;
	info->tx_aborting = false;

	if (info->params.mode == MGSL_MODE_ASYNC)
		return;

	info->tx_count = info->tx_put = info->tx_get = 0;
	del_timer(&info->tx_timer);

	if (info->drop_rts_on_tx_done) {
		get_signals(info);
		if (info->serial_signals & SerialSignal_RTS) {
			info->serial_signals &= ~SerialSignal_RTS;
			set_signals(info);
		}
		info->drop_rts_on_tx_done = false;
	}

#if SYNCLINK_GENERIC_HDLC
	if (info->netcount)
		hdlcdev_tx_done(info);
	else
#endif
	{
		if (tty->stopped || tty->hw_stopped) {
			tx_stop(info);
			return;
		}
		info->pending_bh |= BH_TRANSMIT;
	}
}

static void tx_ready(MGSLPC_INFO *info, struct tty_struct *tty)
{
	unsigned char fifo_count = 32;
	int c;

	if (debug_level >= DEBUG_LEVEL_ISR)
		printk("%s(%d):tx_ready(%s)\n", __FILE__,__LINE__,info->device_name);

	if (info->params.mode == MGSL_MODE_HDLC) {
		if (!info->tx_active)
			return;
	} else {
		if (tty->stopped || tty->hw_stopped) {
			tx_stop(info);
			return;
		}
		if (!info->tx_count)
			info->tx_active = false;
	}

	if (!info->tx_count)
		return;

	while (info->tx_count && fifo_count) {
		c = min(2, min_t(int, fifo_count, min(info->tx_count, TXBUFSIZE - info->tx_get)));

		if (c == 1) {
			write_reg(info, CHA + TXFIFO, *(info->tx_buf + info->tx_get));
		} else {
			write_reg16(info, CHA + TXFIFO,
					  *((unsigned short*)(info->tx_buf + info->tx_get)));
		}
		info->tx_count -= c;
		info->tx_get = (info->tx_get + c) & (TXBUFSIZE - 1);
		fifo_count -= c;
	}

	if (info->params.mode == MGSL_MODE_ASYNC) {
		if (info->tx_count < WAKEUP_CHARS)
			info->pending_bh |= BH_TRANSMIT;
		issue_command(info, CHA, CMD_TXFIFO);
	} else {
		if (info->tx_count)
			issue_command(info, CHA, CMD_TXFIFO);
		else
			issue_command(info, CHA, CMD_TXFIFO + CMD_TXEOM);
	}
}

static void cts_change(MGSLPC_INFO *info, struct tty_struct *tty)
{
	get_signals(info);
	if ((info->cts_chkcount)++ >= IO_PIN_SHUTDOWN_LIMIT)
		irq_disable(info, CHB, IRQ_CTS);
	info->icount.cts++;
	if (info->serial_signals & SerialSignal_CTS)
		info->input_signal_events.cts_up++;
	else
		info->input_signal_events.cts_down++;
	wake_up_interruptible(&info->status_event_wait_q);
	wake_up_interruptible(&info->event_wait_q);

	if (info->port.flags & ASYNC_CTS_FLOW) {
		if (tty->hw_stopped) {
			if (info->serial_signals & SerialSignal_CTS) {
				if (debug_level >= DEBUG_LEVEL_ISR)
					printk("CTS tx start...");
				if (tty)
					tty->hw_stopped = 0;
				tx_start(info, tty);
				info->pending_bh |= BH_TRANSMIT;
				return;
			}
		} else {
			if (!(info->serial_signals & SerialSignal_CTS)) {
				if (debug_level >= DEBUG_LEVEL_ISR)
					printk("CTS tx stop...");
				if (tty)
					tty->hw_stopped = 1;
				tx_stop(info);
			}
		}
	}
	info->pending_bh |= BH_STATUS;
}

static void dcd_change(MGSLPC_INFO *info, struct tty_struct *tty)
{
	get_signals(info);
	if ((info->dcd_chkcount)++ >= IO_PIN_SHUTDOWN_LIMIT)
		irq_disable(info, CHB, IRQ_DCD);
	info->icount.dcd++;
	if (info->serial_signals & SerialSignal_DCD) {
		info->input_signal_events.dcd_up++;
	}
	else
		info->input_signal_events.dcd_down++;
#if SYNCLINK_GENERIC_HDLC
	if (info->netcount) {
		if (info->serial_signals & SerialSignal_DCD)
			netif_carrier_on(info->netdev);
		else
			netif_carrier_off(info->netdev);
	}
#endif
	wake_up_interruptible(&info->status_event_wait_q);
	wake_up_interruptible(&info->event_wait_q);

	if (info->port.flags & ASYNC_CHECK_CD) {
		if (debug_level >= DEBUG_LEVEL_ISR)
			printk("%s CD now %s...", info->device_name,
			       (info->serial_signals & SerialSignal_DCD) ? "on" : "off");
		if (info->serial_signals & SerialSignal_DCD)
			wake_up_interruptible(&info->port.open_wait);
		else {
			if (debug_level >= DEBUG_LEVEL_ISR)
				printk("doing serial hangup...");
			if (tty)
				tty_hangup(tty);
		}
	}
	info->pending_bh |= BH_STATUS;
}

static void dsr_change(MGSLPC_INFO *info)
{
	get_signals(info);
	if ((info->dsr_chkcount)++ >= IO_PIN_SHUTDOWN_LIMIT)
		port_irq_disable(info, PVR_DSR);
	info->icount.dsr++;
	if (info->serial_signals & SerialSignal_DSR)
		info->input_signal_events.dsr_up++;
	else
		info->input_signal_events.dsr_down++;
	wake_up_interruptible(&info->status_event_wait_q);
	wake_up_interruptible(&info->event_wait_q);
	info->pending_bh |= BH_STATUS;
}

static void ri_change(MGSLPC_INFO *info)
{
	get_signals(info);
	if ((info->ri_chkcount)++ >= IO_PIN_SHUTDOWN_LIMIT)
		port_irq_disable(info, PVR_RI);
	info->icount.rng++;
	if (info->serial_signals & SerialSignal_RI)
		info->input_signal_events.ri_up++;
	else
		info->input_signal_events.ri_down++;
	wake_up_interruptible(&info->status_event_wait_q);
	wake_up_interruptible(&info->event_wait_q);
	info->pending_bh |= BH_STATUS;
}

/* Interrupt service routine entry point.
 *
 * Arguments:
 *
 * irq     interrupt number that caused interrupt
 * dev_id  device ID supplied during interrupt registration
 */
static irqreturn_t mgslpc_isr(int dummy, void *dev_id)
{
	MGSLPC_INFO *info = dev_id;
	struct tty_struct *tty;
	unsigned short isr;
	unsigned char gis, pis;
	int count=0;

	if (debug_level >= DEBUG_LEVEL_ISR)
		printk("mgslpc_isr(%d) entry.\n", info->irq_level);

	if (!(info->p_dev->_locked))
		return IRQ_HANDLED;

	tty = tty_port_tty_get(&info->port);

	spin_lock(&info->lock);

	while ((gis = read_reg(info, CHA + GIS))) {
		if (debug_level >= DEBUG_LEVEL_ISR)
			printk("mgslpc_isr %s gis=%04X\n", info->device_name,gis);

		if ((gis & 0x70) || count > 1000) {
			printk("synclink_cs:hardware failed or ejected\n");
			break;
		}
		count++;

		if (gis & (BIT1 + BIT0)) {
			isr = read_reg16(info, CHB + ISR);
			if (isr & IRQ_DCD)
				dcd_change(info, tty);
			if (isr & IRQ_CTS)
				cts_change(info, tty);
		}
		if (gis & (BIT3 + BIT2))
		{
			isr = read_reg16(info, CHA + ISR);
			if (isr & IRQ_TIMER) {
				info->irq_occurred = true;
				irq_disable(info, CHA, IRQ_TIMER);
			}

			/* receive IRQs */
			if (isr & IRQ_EXITHUNT) {
				info->icount.exithunt++;
				wake_up_interruptible(&info->event_wait_q);
			}
			if (isr & IRQ_BREAK_ON) {
				info->icount.brk++;
				if (info->port.flags & ASYNC_SAK)
					do_SAK(tty);
			}
			if (isr & IRQ_RXTIME) {
				issue_command(info, CHA, CMD_RXFIFO_READ);
			}
			if (isr & (IRQ_RXEOM + IRQ_RXFIFO)) {
				if (info->params.mode == MGSL_MODE_HDLC)
					rx_ready_hdlc(info, isr & IRQ_RXEOM);
				else
					rx_ready_async(info, isr & IRQ_RXEOM, tty);
			}

			/* transmit IRQs */
			if (isr & IRQ_UNDERRUN) {
				if (info->tx_aborting)
					info->icount.txabort++;
				else
					info->icount.txunder++;
				tx_done(info, tty);
			}
			else if (isr & IRQ_ALLSENT) {
				info->icount.txok++;
				tx_done(info, tty);
			}
			else if (isr & IRQ_TXFIFO)
				tx_ready(info, tty);
		}
		if (gis & BIT7) {
			pis = read_reg(info, CHA + PIS);
			if (pis & BIT1)
				dsr_change(info);
			if (pis & BIT2)
				ri_change(info);
		}
	}

	/* Request bottom half processing if there's something
	 * for it to do and the bh is not already running
	 */

	if (info->pending_bh && !info->bh_running && !info->bh_requested) {
		if ( debug_level >= DEBUG_LEVEL_ISR )
			printk("%s(%d):%s queueing bh task.\n",
				__FILE__,__LINE__,info->device_name);
		schedule_work(&info->task);
		info->bh_requested = true;
	}

	spin_unlock(&info->lock);
	tty_kref_put(tty);

	if (debug_level >= DEBUG_LEVEL_ISR)
		printk("%s(%d):mgslpc_isr(%d)exit.\n",
		       __FILE__, __LINE__, info->irq_level);

	return IRQ_HANDLED;
}

/* Initialize and start device.
 */
static int startup(MGSLPC_INFO * info, struct tty_struct *tty)
{
	int retval = 0;

	if (debug_level >= DEBUG_LEVEL_INFO)
		printk("%s(%d):startup(%s)\n",__FILE__,__LINE__,info->device_name);

	if (info->port.flags & ASYNC_INITIALIZED)
		return 0;

	if (!info->tx_buf) {
		/* allocate a page of memory for a transmit buffer */
		info->tx_buf = (unsigned char *)get_zeroed_page(GFP_KERNEL);
		if (!info->tx_buf) {
			printk(KERN_ERR"%s(%d):%s can't allocate transmit buffer\n",
				__FILE__,__LINE__,info->device_name);
			return -ENOMEM;
		}
	}

	info->pending_bh = 0;

	memset(&info->icount, 0, sizeof(info->icount));

	setup_timer(&info->tx_timer, tx_timeout, (unsigned long)info);

	/* Allocate and claim adapter resources */
	retval = claim_resources(info);

	/* perform existance check and diagnostics */
	if ( !retval )
		retval = adapter_test(info);

	if ( retval ) {
  		if (capable(CAP_SYS_ADMIN) && tty)
			set_bit(TTY_IO_ERROR, &tty->flags);
		release_resources(info);
  		return retval;
  	}

	/* program hardware for current parameters */
	mgslpc_change_params(info, tty);

	if (tty)
		clear_bit(TTY_IO_ERROR, &tty->flags);

	info->port.flags |= ASYNC_INITIALIZED;

	return 0;
}

/* Called by mgslpc_close() and mgslpc_hangup() to shutdown hardware
 */
static void shutdown(MGSLPC_INFO * info, struct tty_struct *tty)
{
	unsigned long flags;

	if (!(info->port.flags & ASYNC_INITIALIZED))
		return;

	if (debug_level >= DEBUG_LEVEL_INFO)
		printk("%s(%d):mgslpc_shutdown(%s)\n",
			 __FILE__,__LINE__, info->device_name );

	/* clear status wait queue because status changes */
	/* can't happen after shutting down the hardware */
	wake_up_interruptible(&info->status_event_wait_q);
	wake_up_interruptible(&info->event_wait_q);

	del_timer_sync(&info->tx_timer);

	if (info->tx_buf) {
		free_page((unsigned long) info->tx_buf);
		info->tx_buf = NULL;
	}

	spin_lock_irqsave(&info->lock,flags);

	rx_stop(info);
	tx_stop(info);

	/* TODO:disable interrupts instead of reset to preserve signal states */
	reset_device(info);

 	if (!tty || tty->termios->c_cflag & HUPCL) {
 		info->serial_signals &= ~(SerialSignal_DTR + SerialSignal_RTS);
		set_signals(info);
	}

	spin_unlock_irqrestore(&info->lock,flags);

	release_resources(info);

	if (tty)
		set_bit(TTY_IO_ERROR, &tty->flags);

	info->port.flags &= ~ASYNC_INITIALIZED;
}

static void mgslpc_program_hw(MGSLPC_INFO *info, struct tty_struct *tty)
{
	unsigned long flags;

	spin_lock_irqsave(&info->lock,flags);

	rx_stop(info);
	tx_stop(info);
	info->tx_count = info->tx_put = info->tx_get = 0;

	if (info->params.mode == MGSL_MODE_HDLC || info->netcount)
		hdlc_mode(info);
	else
		async_mode(info);

	set_signals(info);

	info->dcd_chkcount = 0;
	info->cts_chkcount = 0;
	info->ri_chkcount = 0;
	info->dsr_chkcount = 0;

	irq_enable(info, CHB, IRQ_DCD | IRQ_CTS);
	port_irq_enable(info, (unsigned char) PVR_DSR | PVR_RI);
	get_signals(info);

	if (info->netcount || (tty && (tty->termios->c_cflag & CREAD)))
		rx_start(info);

	spin_unlock_irqrestore(&info->lock,flags);
}

/* Reconfigure adapter based on new parameters
 */
static void mgslpc_change_params(MGSLPC_INFO *info, struct tty_struct *tty)
{
	unsigned cflag;
	int bits_per_char;

	if (!tty || !tty->termios)
		return;

	if (debug_level >= DEBUG_LEVEL_INFO)
		printk("%s(%d):mgslpc_change_params(%s)\n",
			 __FILE__,__LINE__, info->device_name );

	cflag = tty->termios->c_cflag;

	/* if B0 rate (hangup) specified then negate DTR and RTS */
	/* otherwise assert DTR and RTS */
 	if (cflag & CBAUD)
		info->serial_signals |= SerialSignal_RTS + SerialSignal_DTR;
	else
		info->serial_signals &= ~(SerialSignal_RTS + SerialSignal_DTR);

	/* byte size and parity */

	switch (cflag & CSIZE) {
	case CS5: info->params.data_bits = 5; break;
	case CS6: info->params.data_bits = 6; break;
	case CS7: info->params.data_bits = 7; break;
	case CS8: info->params.data_bits = 8; break;
	default:  info->params.data_bits = 7; break;
	}

	if (cflag & CSTOPB)
		info->params.stop_bits = 2;
	else
		info->params.stop_bits = 1;

	info->params.parity = ASYNC_PARITY_NONE;
	if (cflag & PARENB) {
		if (cflag & PARODD)
			info->params.parity = ASYNC_PARITY_ODD;
		else
			info->params.parity = ASYNC_PARITY_EVEN;
#ifdef CMSPAR
		if (cflag & CMSPAR)
			info->params.parity = ASYNC_PARITY_SPACE;
#endif
	}

	/* calculate number of jiffies to transmit a full
	 * FIFO (32 bytes) at specified data rate
	 */
	bits_per_char = info->params.data_bits +
			info->params.stop_bits + 1;

	/* if port data rate is set to 460800 or less then
	 * allow tty settings to override, otherwise keep the
	 * current data rate.
	 */
	if (info->params.data_rate <= 460800) {
		info->params.data_rate = tty_get_baud_rate(tty);
	}

	if ( info->params.data_rate ) {
		info->timeout = (32*HZ*bits_per_char) /
				info->params.data_rate;
	}
	info->timeout += HZ/50;		/* Add .02 seconds of slop */

	if (cflag & CRTSCTS)
		info->port.flags |= ASYNC_CTS_FLOW;
	else
		info->port.flags &= ~ASYNC_CTS_FLOW;

	if (cflag & CLOCAL)
		info->port.flags &= ~ASYNC_CHECK_CD;
	else
		info->port.flags |= ASYNC_CHECK_CD;

	/* process tty input control flags */

	info->read_status_mask = 0;
	if (I_INPCK(tty))
		info->read_status_mask |= BIT7 | BIT6;
	if (I_IGNPAR(tty))
		info->ignore_status_mask |= BIT7 | BIT6;

	mgslpc_program_hw(info, tty);
}

/* Add a character to the transmit buffer
 */
static int mgslpc_put_char(struct tty_struct *tty, unsigned char ch)
{
	MGSLPC_INFO *info = (MGSLPC_INFO *)tty->driver_data;
	unsigned long flags;

	if (debug_level >= DEBUG_LEVEL_INFO) {
		printk( "%s(%d):mgslpc_put_char(%d) on %s\n",
			__FILE__,__LINE__,ch,info->device_name);
	}

	if (mgslpc_paranoia_check(info, tty->name, "mgslpc_put_char"))
		return 0;

	if (!info->tx_buf)
		return 0;

	spin_lock_irqsave(&info->lock,flags);

	if (info->params.mode == MGSL_MODE_ASYNC || !info->tx_active) {
		if (info->tx_count < TXBUFSIZE - 1) {
			info->tx_buf[info->tx_put++] = ch;
			info->tx_put &= TXBUFSIZE-1;
			info->tx_count++;
		}
	}

	spin_unlock_irqrestore(&info->lock,flags);
	return 1;
}

/* Enable transmitter so remaining characters in the
 * transmit buffer are sent.
 */
static void mgslpc_flush_chars(struct tty_struct *tty)
{
	MGSLPC_INFO *info = (MGSLPC_INFO *)tty->driver_data;
	unsigned long flags;

	if (debug_level >= DEBUG_LEVEL_INFO)
		printk( "%s(%d):mgslpc_flush_chars() entry on %s tx_count=%d\n",
			__FILE__,__LINE__,info->device_name,info->tx_count);

	if (mgslpc_paranoia_check(info, tty->name, "mgslpc_flush_chars"))
		return;

	if (info->tx_count <= 0 || tty->stopped ||
	    tty->hw_stopped || !info->tx_buf)
		return;

	if (debug_level >= DEBUG_LEVEL_INFO)
		printk( "%s(%d):mgslpc_flush_chars() entry on %s starting transmitter\n",
			__FILE__,__LINE__,info->device_name);

	spin_lock_irqsave(&info->lock,flags);
	if (!info->tx_active)
	 	tx_start(info, tty);
	spin_unlock_irqrestore(&info->lock,flags);
}

/* Send a block of data
 *
 * Arguments:
 *
 * tty        pointer to tty information structure
 * buf	      pointer to buffer containing send data
 * count      size of send data in bytes
 *
 * Returns: number of characters written
 */
static int mgslpc_write(struct tty_struct * tty,
			const unsigned char *buf, int count)
{
	int c, ret = 0;
	MGSLPC_INFO *info = (MGSLPC_INFO *)tty->driver_data;
	unsigned long flags;

	if (debug_level >= DEBUG_LEVEL_INFO)
		printk( "%s(%d):mgslpc_write(%s) count=%d\n",
			__FILE__,__LINE__,info->device_name,count);

	if (mgslpc_paranoia_check(info, tty->name, "mgslpc_write") ||
		!info->tx_buf)
		goto cleanup;

	if (info->params.mode == MGSL_MODE_HDLC) {
		if (count > TXBUFSIZE) {
			ret = -EIO;
			goto cleanup;
		}
		if (info->tx_active)
			goto cleanup;
		else if (info->tx_count)
			goto start;
	}

	for (;;) {
		c = min(count,
			min(TXBUFSIZE - info->tx_count - 1,
			    TXBUFSIZE - info->tx_put));
		if (c <= 0)
			break;

		memcpy(info->tx_buf + info->tx_put, buf, c);

		spin_lock_irqsave(&info->lock,flags);
		info->tx_put = (info->tx_put + c) & (TXBUFSIZE-1);
		info->tx_count += c;
		spin_unlock_irqrestore(&info->lock,flags);

		buf += c;
		count -= c;
		ret += c;
	}
start:
 	if (info->tx_count && !tty->stopped && !tty->hw_stopped) {
		spin_lock_irqsave(&info->lock,flags);
		if (!info->tx_active)
		 	tx_start(info, tty);
		spin_unlock_irqrestore(&info->lock,flags);
 	}
cleanup:
	if (debug_level >= DEBUG_LEVEL_INFO)
		printk( "%s(%d):mgslpc_write(%s) returning=%d\n",
			__FILE__,__LINE__,info->device_name,ret);
	return ret;
}

/* Return the count of free bytes in transmit buffer
 */
static int mgslpc_write_room(struct tty_struct *tty)
{
	MGSLPC_INFO *info = (MGSLPC_INFO *)tty->driver_data;
	int ret;

	if (mgslpc_paranoia_check(info, tty->name, "mgslpc_write_room"))
		return 0;

	if (info->params.mode == MGSL_MODE_HDLC) {
		/* HDLC (frame oriented) mode */
		if (info->tx_active)
			return 0;
		else
			return HDLC_MAX_FRAME_SIZE;
	} else {
		ret = TXBUFSIZE - info->tx_count - 1;
		if (ret < 0)
			ret = 0;
	}

	if (debug_level >= DEBUG_LEVEL_INFO)
		printk("%s(%d):mgslpc_write_room(%s)=%d\n",
			 __FILE__,__LINE__, info->device_name, ret);
	return ret;
}

/* Return the count of bytes in transmit buffer
 */
static int mgslpc_chars_in_buffer(struct tty_struct *tty)
{
	MGSLPC_INFO *info = (MGSLPC_INFO *)tty->driver_data;
	int rc;

	if (debug_level >= DEBUG_LEVEL_INFO)
		printk("%s(%d):mgslpc_chars_in_buffer(%s)\n",
			 __FILE__,__LINE__, info->device_name );

	if (mgslpc_paranoia_check(info, tty->name, "mgslpc_chars_in_buffer"))
		return 0;

	if (info->params.mode == MGSL_MODE_HDLC)
		rc = info->tx_active ? info->max_frame_size : 0;
	else
		rc = info->tx_count;

	if (debug_level >= DEBUG_LEVEL_INFO)
		printk("%s(%d):mgslpc_chars_in_buffer(%s)=%d\n",
			 __FILE__,__LINE__, info->device_name, rc);

	return rc;
}

/* Discard all data in the send buffer
 */
static void mgslpc_flush_buffer(struct tty_struct *tty)
{
	MGSLPC_INFO *info = (MGSLPC_INFO *)tty->driver_data;
	unsigned long flags;

	if (debug_level >= DEBUG_LEVEL_INFO)
		printk("%s(%d):mgslpc_flush_buffer(%s) entry\n",
			 __FILE__,__LINE__, info->device_name );

	if (mgslpc_paranoia_check(info, tty->name, "mgslpc_flush_buffer"))
		return;

	spin_lock_irqsave(&info->lock,flags);
	info->tx_count = info->tx_put = info->tx_get = 0;
	del_timer(&info->tx_timer);
	spin_unlock_irqrestore(&info->lock,flags);

	wake_up_interruptible(&tty->write_wait);
	tty_wakeup(tty);
}

/* Send a high-priority XON/XOFF character
 */
static void mgslpc_send_xchar(struct tty_struct *tty, char ch)
{
	MGSLPC_INFO *info = (MGSLPC_INFO *)tty->driver_data;
	unsigned long flags;

	if (debug_level >= DEBUG_LEVEL_INFO)
		printk("%s(%d):mgslpc_send_xchar(%s,%d)\n",
			 __FILE__,__LINE__, info->device_name, ch );

	if (mgslpc_paranoia_check(info, tty->name, "mgslpc_send_xchar"))
		return;

	info->x_char = ch;
	if (ch) {
		spin_lock_irqsave(&info->lock,flags);
		if (!info->tx_enabled)
		 	tx_start(info, tty);
		spin_unlock_irqrestore(&info->lock,flags);
	}
}

/* Signal remote device to throttle send data (our receive data)
 */
static void mgslpc_throttle(struct tty_struct * tty)
{
	MGSLPC_INFO *info = (MGSLPC_INFO *)tty->driver_data;
	unsigned long flags;

	if (debug_level >= DEBUG_LEVEL_INFO)
		printk("%s(%d):mgslpc_throttle(%s) entry\n",
			 __FILE__,__LINE__, info->device_name );

	if (mgslpc_paranoia_check(info, tty->name, "mgslpc_throttle"))
		return;

	if (I_IXOFF(tty))
		mgslpc_send_xchar(tty, STOP_CHAR(tty));

 	if (tty->termios->c_cflag & CRTSCTS) {
		spin_lock_irqsave(&info->lock,flags);
		info->serial_signals &= ~SerialSignal_RTS;
	 	set_signals(info);
		spin_unlock_irqrestore(&info->lock,flags);
	}
}

/* Signal remote device to stop throttling send data (our receive data)
 */
static void mgslpc_unthrottle(struct tty_struct * tty)
{
	MGSLPC_INFO *info = (MGSLPC_INFO *)tty->driver_data;
	unsigned long flags;

	if (debug_level >= DEBUG_LEVEL_INFO)
		printk("%s(%d):mgslpc_unthrottle(%s) entry\n",
			 __FILE__,__LINE__, info->device_name );

	if (mgslpc_paranoia_check(info, tty->name, "mgslpc_unthrottle"))
		return;

	if (I_IXOFF(tty)) {
		if (info->x_char)
			info->x_char = 0;
		else
			mgslpc_send_xchar(tty, START_CHAR(tty));
	}

 	if (tty->termios->c_cflag & CRTSCTS) {
		spin_lock_irqsave(&info->lock,flags);
		info->serial_signals |= SerialSignal_RTS;
	 	set_signals(info);
		spin_unlock_irqrestore(&info->lock,flags);
	}
}

/* get the current serial statistics
 */
static int get_stats(MGSLPC_INFO * info, struct mgsl_icount __user *user_icount)
{
	int err;
	if (debug_level >= DEBUG_LEVEL_INFO)
		printk("get_params(%s)\n", info->device_name);
	if (!user_icount) {
		memset(&info->icount, 0, sizeof(info->icount));
	} else {
		COPY_TO_USER(err, user_icount, &info->icount, sizeof(struct mgsl_icount));
		if (err)
			return -EFAULT;
	}
	return 0;
}

/* get the current serial parameters
 */
static int get_params(MGSLPC_INFO * info, MGSL_PARAMS __user *user_params)
{
	int err;
	if (debug_level >= DEBUG_LEVEL_INFO)
		printk("get_params(%s)\n", info->device_name);
	COPY_TO_USER(err,user_params, &info->params, sizeof(MGSL_PARAMS));
	if (err)
		return -EFAULT;
	return 0;
}

/* set the serial parameters
 *
 * Arguments:
 *
 * 	info		pointer to device instance data
 * 	new_params	user buffer containing new serial params
 *
 * Returns:	0 if success, otherwise error code
 */
static int set_params(MGSLPC_INFO * info, MGSL_PARAMS __user *new_params, struct tty_struct *tty)
{
 	unsigned long flags;
	MGSL_PARAMS tmp_params;
	int err;

	if (debug_level >= DEBUG_LEVEL_INFO)
		printk("%s(%d):set_params %s\n", __FILE__,__LINE__,
			info->device_name );
	COPY_FROM_USER(err,&tmp_params, new_params, sizeof(MGSL_PARAMS));
	if (err) {
		if ( debug_level >= DEBUG_LEVEL_INFO )
			printk( "%s(%d):set_params(%s) user buffer copy failed\n",
				__FILE__,__LINE__,info->device_name);
		return -EFAULT;
	}

	spin_lock_irqsave(&info->lock,flags);
	memcpy(&info->params,&tmp_params,sizeof(MGSL_PARAMS));
	spin_unlock_irqrestore(&info->lock,flags);

 	mgslpc_change_params(info, tty);

	return 0;
}

static int get_txidle(MGSLPC_INFO * info, int __user *idle_mode)
{
	int err;
	if (debug_level >= DEBUG_LEVEL_INFO)
		printk("get_txidle(%s)=%d\n", info->device_name, info->idle_mode);
	COPY_TO_USER(err,idle_mode, &info->idle_mode, sizeof(int));
	if (err)
		return -EFAULT;
	return 0;
}

static int set_txidle(MGSLPC_INFO * info, int idle_mode)
{
 	unsigned long flags;
	if (debug_level >= DEBUG_LEVEL_INFO)
		printk("set_txidle(%s,%d)\n", info->device_name, idle_mode);
	spin_lock_irqsave(&info->lock,flags);
	info->idle_mode = idle_mode;
	tx_set_idle(info);
	spin_unlock_irqrestore(&info->lock,flags);
	return 0;
}

static int get_interface(MGSLPC_INFO * info, int __user *if_mode)
{
	int err;
	if (debug_level >= DEBUG_LEVEL_INFO)
		printk("get_interface(%s)=%d\n", info->device_name, info->if_mode);
	COPY_TO_USER(err,if_mode, &info->if_mode, sizeof(int));
	if (err)
		return -EFAULT;
	return 0;
}

static int set_interface(MGSLPC_INFO * info, int if_mode)
{
 	unsigned long flags;
	unsigned char val;
	if (debug_level >= DEBUG_LEVEL_INFO)
		printk("set_interface(%s,%d)\n", info->device_name, if_mode);
	spin_lock_irqsave(&info->lock,flags);
	info->if_mode = if_mode;

	val = read_reg(info, PVR) & 0x0f;
	switch (info->if_mode)
	{
	case MGSL_INTERFACE_RS232: val |= PVR_RS232; break;
	case MGSL_INTERFACE_V35:   val |= PVR_V35;   break;
	case MGSL_INTERFACE_RS422: val |= PVR_RS422; break;
	}
	write_reg(info, PVR, val);

	spin_unlock_irqrestore(&info->lock,flags);
	return 0;
}

static int set_txenable(MGSLPC_INFO * info, int enable, struct tty_struct *tty)
{
 	unsigned long flags;

	if (debug_level >= DEBUG_LEVEL_INFO)
		printk("set_txenable(%s,%d)\n", info->device_name, enable);

	spin_lock_irqsave(&info->lock,flags);
	if (enable) {
		if (!info->tx_enabled)
			tx_start(info, tty);
	} else {
		if (info->tx_enabled)
			tx_stop(info);
	}
	spin_unlock_irqrestore(&info->lock,flags);
	return 0;
}

static int tx_abort(MGSLPC_INFO * info)
{
 	unsigned long flags;

	if (debug_level >= DEBUG_LEVEL_INFO)
		printk("tx_abort(%s)\n", info->device_name);

	spin_lock_irqsave(&info->lock,flags);
	if (info->tx_active && info->tx_count &&
	    info->params.mode == MGSL_MODE_HDLC) {
		/* clear data count so FIFO is not filled on next IRQ.
		 * This results in underrun and abort transmission.
		 */
		info->tx_count = info->tx_put = info->tx_get = 0;
		info->tx_aborting = true;
	}
	spin_unlock_irqrestore(&info->lock,flags);
	return 0;
}

static int set_rxenable(MGSLPC_INFO * info, int enable)
{
 	unsigned long flags;

	if (debug_level >= DEBUG_LEVEL_INFO)
		printk("set_rxenable(%s,%d)\n", info->device_name, enable);

	spin_lock_irqsave(&info->lock,flags);
	if (enable) {
		if (!info->rx_enabled)
			rx_start(info);
	} else {
		if (info->rx_enabled)
			rx_stop(info);
	}
	spin_unlock_irqrestore(&info->lock,flags);
	return 0;
}

/* wait for specified event to occur
 *
 * Arguments:	 	info	pointer to device instance data
 * 			mask	pointer to bitmask of events to wait for
 * Return Value:	0 	if successful and bit mask updated with
 *				of events triggerred,
 * 			otherwise error code
 */
static int wait_events(MGSLPC_INFO * info, int __user *mask_ptr)
{
 	unsigned long flags;
	int s;
	int rc=0;
	struct mgsl_icount cprev, cnow;
	int events;
	int mask;
	struct	_input_signal_events oldsigs, newsigs;
	DECLARE_WAITQUEUE(wait, current);

	COPY_FROM_USER(rc,&mask, mask_ptr, sizeof(int));
	if (rc)
		return  -EFAULT;

	if (debug_level >= DEBUG_LEVEL_INFO)
		printk("wait_events(%s,%d)\n", info->device_name, mask);

	spin_lock_irqsave(&info->lock,flags);

	/* return immediately if state matches requested events */
	get_signals(info);
	s = info->serial_signals;
	events = mask &
		( ((s & SerialSignal_DSR) ? MgslEvent_DsrActive:MgslEvent_DsrInactive) +
 		  ((s & SerialSignal_DCD) ? MgslEvent_DcdActive:MgslEvent_DcdInactive) +
		  ((s & SerialSignal_CTS) ? MgslEvent_CtsActive:MgslEvent_CtsInactive) +
		  ((s & SerialSignal_RI)  ? MgslEvent_RiActive :MgslEvent_RiInactive) );
	if (events) {
		spin_unlock_irqrestore(&info->lock,flags);
		goto exit;
	}

	/* save current irq counts */
	cprev = info->icount;
	oldsigs = info->input_signal_events;

	if ((info->params.mode == MGSL_MODE_HDLC) &&
	    (mask & MgslEvent_ExitHuntMode))
		irq_enable(info, CHA, IRQ_EXITHUNT);

	set_current_state(TASK_INTERRUPTIBLE);
	add_wait_queue(&info->event_wait_q, &wait);

	spin_unlock_irqrestore(&info->lock,flags);


	for(;;) {
		schedule();
		if (signal_pending(current)) {
			rc = -ERESTARTSYS;
			break;
		}

		/* get current irq counts */
		spin_lock_irqsave(&info->lock,flags);
		cnow = info->icount;
		newsigs = info->input_signal_events;
		set_current_state(TASK_INTERRUPTIBLE);
		spin_unlock_irqrestore(&info->lock,flags);

		/* if no change, wait aborted for some reason */
		if (newsigs.dsr_up   == oldsigs.dsr_up   &&
		    newsigs.dsr_down == oldsigs.dsr_down &&
		    newsigs.dcd_up   == oldsigs.dcd_up   &&
		    newsigs.dcd_down == oldsigs.dcd_down &&
		    newsigs.cts_up   == oldsigs.cts_up   &&
		    newsigs.cts_down == oldsigs.cts_down &&
		    newsigs.ri_up    == oldsigs.ri_up    &&
		    newsigs.ri_down  == oldsigs.ri_down  &&
		    cnow.exithunt    == cprev.exithunt   &&
		    cnow.rxidle      == cprev.rxidle) {
			rc = -EIO;
			break;
		}

		events = mask &
			( (newsigs.dsr_up   != oldsigs.dsr_up   ? MgslEvent_DsrActive:0)   +
			  (newsigs.dsr_down != oldsigs.dsr_down ? MgslEvent_DsrInactive:0) +
			  (newsigs.dcd_up   != oldsigs.dcd_up   ? MgslEvent_DcdActive:0)   +
			  (newsigs.dcd_down != oldsigs.dcd_down ? MgslEvent_DcdInactive:0) +
			  (newsigs.cts_up   != oldsigs.cts_up   ? MgslEvent_CtsActive:0)   +
			  (newsigs.cts_down != oldsigs.cts_down ? MgslEvent_CtsInactive:0) +
			  (newsigs.ri_up    != oldsigs.ri_up    ? MgslEvent_RiActive:0)    +
			  (newsigs.ri_down  != oldsigs.ri_down  ? MgslEvent_RiInactive:0)  +
			  (cnow.exithunt    != cprev.exithunt   ? MgslEvent_ExitHuntMode:0) +
			  (cnow.rxidle      != cprev.rxidle     ? MgslEvent_IdleReceived:0) );
		if (events)
			break;

		cprev = cnow;
		oldsigs = newsigs;
	}

	remove_wait_queue(&info->event_wait_q, &wait);
	set_current_state(TASK_RUNNING);

	if (mask & MgslEvent_ExitHuntMode) {
		spin_lock_irqsave(&info->lock,flags);
		if (!waitqueue_active(&info->event_wait_q))
			irq_disable(info, CHA, IRQ_EXITHUNT);
		spin_unlock_irqrestore(&info->lock,flags);
	}
exit:
	if (rc == 0)
		PUT_USER(rc, events, mask_ptr);
	return rc;
}

static int modem_input_wait(MGSLPC_INFO *info,int arg)
{
 	unsigned long flags;
	int rc;
	struct mgsl_icount cprev, cnow;
	DECLARE_WAITQUEUE(wait, current);

	/* save current irq counts */
	spin_lock_irqsave(&info->lock,flags);
	cprev = info->icount;
	add_wait_queue(&info->status_event_wait_q, &wait);
	set_current_state(TASK_INTERRUPTIBLE);
	spin_unlock_irqrestore(&info->lock,flags);

	for(;;) {
		schedule();
		if (signal_pending(current)) {
			rc = -ERESTARTSYS;
			break;
		}

		/* get new irq counts */
		spin_lock_irqsave(&info->lock,flags);
		cnow = info->icount;
		set_current_state(TASK_INTERRUPTIBLE);
		spin_unlock_irqrestore(&info->lock,flags);

		/* if no change, wait aborted for some reason */
		if (cnow.rng == cprev.rng && cnow.dsr == cprev.dsr &&
		    cnow.dcd == cprev.dcd && cnow.cts == cprev.cts) {
			rc = -EIO;
			break;
		}

		/* check for change in caller specified modem input */
		if ((arg & TIOCM_RNG && cnow.rng != cprev.rng) ||
		    (arg & TIOCM_DSR && cnow.dsr != cprev.dsr) ||
		    (arg & TIOCM_CD  && cnow.dcd != cprev.dcd) ||
		    (arg & TIOCM_CTS && cnow.cts != cprev.cts)) {
			rc = 0;
			break;
		}

		cprev = cnow;
	}
	remove_wait_queue(&info->status_event_wait_q, &wait);
	set_current_state(TASK_RUNNING);
	return rc;
}

/* return the state of the serial control and status signals
 */
static int tiocmget(struct tty_struct *tty, struct file *file)
{
	MGSLPC_INFO *info = (MGSLPC_INFO *)tty->driver_data;
	unsigned int result;
 	unsigned long flags;

	spin_lock_irqsave(&info->lock,flags);
 	get_signals(info);
	spin_unlock_irqrestore(&info->lock,flags);

	result = ((info->serial_signals & SerialSignal_RTS) ? TIOCM_RTS:0) +
		((info->serial_signals & SerialSignal_DTR) ? TIOCM_DTR:0) +
		((info->serial_signals & SerialSignal_DCD) ? TIOCM_CAR:0) +
		((info->serial_signals & SerialSignal_RI)  ? TIOCM_RNG:0) +
		((info->serial_signals & SerialSignal_DSR) ? TIOCM_DSR:0) +
		((info->serial_signals & SerialSignal_CTS) ? TIOCM_CTS:0);

	if (debug_level >= DEBUG_LEVEL_INFO)
		printk("%s(%d):%s tiocmget() value=%08X\n",
			 __FILE__,__LINE__, info->device_name, result );
	return result;
}

/* set modem control signals (DTR/RTS)
 */
static int tiocmset(struct tty_struct *tty, struct file *file,
		    unsigned int set, unsigned int clear)
{
	MGSLPC_INFO *info = (MGSLPC_INFO *)tty->driver_data;
 	unsigned long flags;

	if (debug_level >= DEBUG_LEVEL_INFO)
		printk("%s(%d):%s tiocmset(%x,%x)\n",
			__FILE__,__LINE__,info->device_name, set, clear);

	if (set & TIOCM_RTS)
		info->serial_signals |= SerialSignal_RTS;
	if (set & TIOCM_DTR)
		info->serial_signals |= SerialSignal_DTR;
	if (clear & TIOCM_RTS)
		info->serial_signals &= ~SerialSignal_RTS;
	if (clear & TIOCM_DTR)
		info->serial_signals &= ~SerialSignal_DTR;

	spin_lock_irqsave(&info->lock,flags);
 	set_signals(info);
	spin_unlock_irqrestore(&info->lock,flags);

	return 0;
}

/* Set or clear transmit break condition
 *
 * Arguments:		tty		pointer to tty instance data
 *			break_state	-1=set break condition, 0=clear
 */
static int mgslpc_break(struct tty_struct *tty, int break_state)
{
	MGSLPC_INFO * info = (MGSLPC_INFO *)tty->driver_data;
	unsigned long flags;

	if (debug_level >= DEBUG_LEVEL_INFO)
		printk("%s(%d):mgslpc_break(%s,%d)\n",
			 __FILE__,__LINE__, info->device_name, break_state);

	if (mgslpc_paranoia_check(info, tty->name, "mgslpc_break"))
		return -EINVAL;

	spin_lock_irqsave(&info->lock,flags);
 	if (break_state == -1)
		set_reg_bits(info, CHA+DAFO, BIT6);
	else
		clear_reg_bits(info, CHA+DAFO, BIT6);
	spin_unlock_irqrestore(&info->lock,flags);
	return 0;
}

/* Service an IOCTL request
 *
 * Arguments:
 *
 * 	tty	pointer to tty instance data
 * 	file	pointer to associated file object for device
 * 	cmd	IOCTL command code
 * 	arg	command argument/context
 *
 * Return Value:	0 if success, otherwise error code
 */
static int mgslpc_ioctl(struct tty_struct *tty, struct file * file,
			unsigned int cmd, unsigned long arg)
{
	MGSLPC_INFO * info = (MGSLPC_INFO *)tty->driver_data;
	int error;
	struct mgsl_icount cnow;	/* kernel counter temps */
	struct serial_icounter_struct __user *p_cuser;	/* user space */
	void __user *argp = (void __user *)arg;
	unsigned long flags;

	if (debug_level >= DEBUG_LEVEL_INFO)
		printk("%s(%d):mgslpc_ioctl %s cmd=%08X\n", __FILE__,__LINE__,
			info->device_name, cmd );

	if (mgslpc_paranoia_check(info, tty->name, "mgslpc_ioctl"))
		return -ENODEV;

	if ((cmd != TIOCGSERIAL) && (cmd != TIOCSSERIAL) &&
	    (cmd != TIOCMIWAIT) && (cmd != TIOCGICOUNT)) {
		if (tty->flags & (1 << TTY_IO_ERROR))
		    return -EIO;
	}

	switch (cmd) {
	case MGSL_IOCGPARAMS:
		return get_params(info, argp);
	case MGSL_IOCSPARAMS:
		return set_params(info, argp, tty);
	case MGSL_IOCGTXIDLE:
		return get_txidle(info, argp);
	case MGSL_IOCSTXIDLE:
		return set_txidle(info, (int)arg);
	case MGSL_IOCGIF:
		return get_interface(info, argp);
	case MGSL_IOCSIF:
		return set_interface(info,(int)arg);
	case MGSL_IOCTXENABLE:
		return set_txenable(info,(int)arg, tty);
	case MGSL_IOCRXENABLE:
		return set_rxenable(info,(int)arg);
	case MGSL_IOCTXABORT:
		return tx_abort(info);
	case MGSL_IOCGSTATS:
		return get_stats(info, argp);
	case MGSL_IOCWAITEVENT:
		return wait_events(info, argp);
	case TIOCMIWAIT:
		return modem_input_wait(info,(int)arg);
	case TIOCGICOUNT:
		spin_lock_irqsave(&info->lock,flags);
		cnow = info->icount;
		spin_unlock_irqrestore(&info->lock,flags);
		p_cuser = argp;
		PUT_USER(error,cnow.cts, &p_cuser->cts);
		if (error) return error;
		PUT_USER(error,cnow.dsr, &p_cuser->dsr);
		if (error) return error;
		PUT_USER(error,cnow.rng, &p_cuser->rng);
		if (error) return error;
		PUT_USER(error,cnow.dcd, &p_cuser->dcd);
		if (error) return error;
		PUT_USER(error,cnow.rx, &p_cuser->rx);
		if (error) return error;
		PUT_USER(error,cnow.tx, &p_cuser->tx);
		if (error) return error;
		PUT_USER(error,cnow.frame, &p_cuser->frame);
		if (error) return error;
		PUT_USER(error,cnow.overrun, &p_cuser->overrun);
		if (error) return error;
		PUT_USER(error,cnow.parity, &p_cuser->parity);
		if (error) return error;
		PUT_USER(error,cnow.brk, &p_cuser->brk);
		if (error) return error;
		PUT_USER(error,cnow.buf_overrun, &p_cuser->buf_overrun);
		if (error) return error;
		return 0;
	default:
		return -ENOIOCTLCMD;
	}
	return 0;
}

/* Set new termios settings
 *
 * Arguments:
 *
 * 	tty		pointer to tty structure
 * 	termios		pointer to buffer to hold returned old termios
 */
static void mgslpc_set_termios(struct tty_struct *tty, struct ktermios *old_termios)
{
	MGSLPC_INFO *info = (MGSLPC_INFO *)tty->driver_data;
	unsigned long flags;

	if (debug_level >= DEBUG_LEVEL_INFO)
		printk("%s(%d):mgslpc_set_termios %s\n", __FILE__,__LINE__,
			tty->driver->name );

	/* just return if nothing has changed */
	if ((tty->termios->c_cflag == old_termios->c_cflag)
	    && (RELEVANT_IFLAG(tty->termios->c_iflag)
		== RELEVANT_IFLAG(old_termios->c_iflag)))
	  return;

	mgslpc_change_params(info, tty);

	/* Handle transition to B0 status */
	if (old_termios->c_cflag & CBAUD &&
	    !(tty->termios->c_cflag & CBAUD)) {
		info->serial_signals &= ~(SerialSignal_RTS + SerialSignal_DTR);
		spin_lock_irqsave(&info->lock,flags);
	 	set_signals(info);
		spin_unlock_irqrestore(&info->lock,flags);
	}

	/* Handle transition away from B0 status */
	if (!(old_termios->c_cflag & CBAUD) &&
	    tty->termios->c_cflag & CBAUD) {
		info->serial_signals |= SerialSignal_DTR;
 		if (!(tty->termios->c_cflag & CRTSCTS) ||
 		    !test_bit(TTY_THROTTLED, &tty->flags)) {
			info->serial_signals |= SerialSignal_RTS;
 		}
		spin_lock_irqsave(&info->lock,flags);
	 	set_signals(info);
		spin_unlock_irqrestore(&info->lock,flags);
	}

	/* Handle turning off CRTSCTS */
	if (old_termios->c_cflag & CRTSCTS &&
	    !(tty->termios->c_cflag & CRTSCTS)) {
		tty->hw_stopped = 0;
		tx_release(tty);
	}
}

static void mgslpc_close(struct tty_struct *tty, struct file * filp)
{
	MGSLPC_INFO * info = (MGSLPC_INFO *)tty->driver_data;
	struct tty_port *port = &info->port;

	if (mgslpc_paranoia_check(info, tty->name, "mgslpc_close"))
		return;

	if (debug_level >= DEBUG_LEVEL_INFO)
		printk("%s(%d):mgslpc_close(%s) entry, count=%d\n",
			 __FILE__,__LINE__, info->device_name, port->count);

	WARN_ON(!port->count);

	if (tty_port_close_start(port, tty, filp) == 0)
		goto cleanup;

 	if (port->flags & ASYNC_INITIALIZED)
 		mgslpc_wait_until_sent(tty, info->timeout);

	mgslpc_flush_buffer(tty);

	tty_ldisc_flush(tty);
	shutdown(info, tty);
	
	tty_port_close_end(port, tty);
	tty_port_tty_set(port, NULL);
cleanup:
	if (debug_level >= DEBUG_LEVEL_INFO)
		printk("%s(%d):mgslpc_close(%s) exit, count=%d\n", __FILE__,__LINE__,
			tty->driver->name, port->count);
}

/* Wait until the transmitter is empty.
 */
static void mgslpc_wait_until_sent(struct tty_struct *tty, int timeout)
{
	MGSLPC_INFO * info = (MGSLPC_INFO *)tty->driver_data;
	unsigned long orig_jiffies, char_time;

	if (!info )
		return;

	if (debug_level >= DEBUG_LEVEL_INFO)
		printk("%s(%d):mgslpc_wait_until_sent(%s) entry\n",
			 __FILE__,__LINE__, info->device_name );

	if (mgslpc_paranoia_check(info, tty->name, "mgslpc_wait_until_sent"))
		return;

	if (!(info->port.flags & ASYNC_INITIALIZED))
		goto exit;

	orig_jiffies = jiffies;

	/* Set check interval to 1/5 of estimated time to
	 * send a character, and make it at least 1. The check
	 * interval should also be less than the timeout.
	 * Note: use tight timings here to satisfy the NIST-PCTS.
	 */

	if ( info->params.data_rate ) {
	       	char_time = info->timeout/(32 * 5);
		if (!char_time)
			char_time++;
	} else
		char_time = 1;

	if (timeout)
		char_time = min_t(unsigned long, char_time, timeout);

	if (info->params.mode == MGSL_MODE_HDLC) {
		while (info->tx_active) {
			msleep_interruptible(jiffies_to_msecs(char_time));
			if (signal_pending(current))
				break;
			if (timeout && time_after(jiffies, orig_jiffies + timeout))
				break;
		}
	} else {
		while ((info->tx_count || info->tx_active) &&
			info->tx_enabled) {
			msleep_interruptible(jiffies_to_msecs(char_time));
			if (signal_pending(current))
				break;
			if (timeout && time_after(jiffies, orig_jiffies + timeout))
				break;
		}
	}

exit:
	if (debug_level >= DEBUG_LEVEL_INFO)
		printk("%s(%d):mgslpc_wait_until_sent(%s) exit\n",
			 __FILE__,__LINE__, info->device_name );
}

/* Called by tty_hangup() when a hangup is signaled.
 * This is the same as closing all open files for the port.
 */
static void mgslpc_hangup(struct tty_struct *tty)
{
	MGSLPC_INFO * info = (MGSLPC_INFO *)tty->driver_data;

	if (debug_level >= DEBUG_LEVEL_INFO)
		printk("%s(%d):mgslpc_hangup(%s)\n",
			 __FILE__,__LINE__, info->device_name );

	if (mgslpc_paranoia_check(info, tty->name, "mgslpc_hangup"))
		return;

	mgslpc_flush_buffer(tty);
	shutdown(info, tty);
	tty_port_hangup(&info->port);
}

static int carrier_raised(struct tty_port *port)
{
	MGSLPC_INFO *info = container_of(port, MGSLPC_INFO, port);
	unsigned long flags;

	spin_lock_irqsave(&info->lock,flags);
 	get_signals(info);
	spin_unlock_irqrestore(&info->lock,flags);

	if (info->serial_signals & SerialSignal_DCD)
		return 1;
	return 0;
}

static void dtr_rts(struct tty_port *port, int onoff)
{
	MGSLPC_INFO *info = container_of(port, MGSLPC_INFO, port);
	unsigned long flags;

	spin_lock_irqsave(&info->lock,flags);
	if (onoff)
		info->serial_signals |= SerialSignal_RTS + SerialSignal_DTR;
	else
		info->serial_signals &= ~SerialSignal_RTS + SerialSignal_DTR;
	set_signals(info);
	spin_unlock_irqrestore(&info->lock,flags);
}


static int mgslpc_open(struct tty_struct *tty, struct file * filp)
{
	MGSLPC_INFO	*info;
	struct tty_port *port;
	int 			retval, line;
	unsigned long flags;

	/* verify range of specified line number */
	line = tty->index;
	if ((line < 0) || (line >= mgslpc_device_count)) {
		printk("%s(%d):mgslpc_open with invalid line #%d.\n",
			__FILE__,__LINE__,line);
		return -ENODEV;
	}

	/* find the info structure for the specified line */
	info = mgslpc_device_list;
	while(info && info->line != line)
		info = info->next_device;
	if (mgslpc_paranoia_check(info, tty->name, "mgslpc_open"))
		return -ENODEV;

	port = &info->port;
	tty->driver_data = info;
	tty_port_tty_set(port, tty);

	if (debug_level >= DEBUG_LEVEL_INFO)
		printk("%s(%d):mgslpc_open(%s), old ref count = %d\n",
			 __FILE__,__LINE__,tty->driver->name, port->count);

	/* If port is closing, signal caller to try again */
	if (tty_hung_up_p(filp) || port->flags & ASYNC_CLOSING){
		if (port->flags & ASYNC_CLOSING)
			interruptible_sleep_on(&port->close_wait);
		retval = ((port->flags & ASYNC_HUP_NOTIFY) ?
			-EAGAIN : -ERESTARTSYS);
		goto cleanup;
	}

	tty->low_latency = (port->flags & ASYNC_LOW_LATENCY) ? 1 : 0;

	spin_lock_irqsave(&info->netlock, flags);
	if (info->netcount) {
		retval = -EBUSY;
		spin_unlock_irqrestore(&info->netlock, flags);
		goto cleanup;
	}
	spin_lock(&port->lock);
	port->count++;
	spin_unlock(&port->lock);
	spin_unlock_irqrestore(&info->netlock, flags);

	if (port->count == 1) {
		/* 1st open on this device, init hardware */
		retval = startup(info, tty);
		if (retval < 0)
			goto cleanup;
	}

	retval = tty_port_block_til_ready(&info->port, tty, filp);
	if (retval) {
		if (debug_level >= DEBUG_LEVEL_INFO)
			printk("%s(%d):block_til_ready(%s) returned %d\n",
				 __FILE__,__LINE__, info->device_name, retval);
		goto cleanup;
	}

	if (debug_level >= DEBUG_LEVEL_INFO)
		printk("%s(%d):mgslpc_open(%s) success\n",
			 __FILE__,__LINE__, info->device_name);
	retval = 0;

cleanup:
	return retval;
}

/*
 * /proc fs routines....
 */

static inline void line_info(struct seq_file *m, MGSLPC_INFO *info)
{
	char	stat_buf[30];
	unsigned long flags;

	seq_printf(m, "%s:io:%04X irq:%d",
		      info->device_name, info->io_base, info->irq_level);

	/* output current serial signal states */
	spin_lock_irqsave(&info->lock,flags);
 	get_signals(info);
	spin_unlock_irqrestore(&info->lock,flags);

	stat_buf[0] = 0;
	stat_buf[1] = 0;
	if (info->serial_signals & SerialSignal_RTS)
		strcat(stat_buf, "|RTS");
	if (info->serial_signals & SerialSignal_CTS)
		strcat(stat_buf, "|CTS");
	if (info->serial_signals & SerialSignal_DTR)
		strcat(stat_buf, "|DTR");
	if (info->serial_signals & SerialSignal_DSR)
		strcat(stat_buf, "|DSR");
	if (info->serial_signals & SerialSignal_DCD)
		strcat(stat_buf, "|CD");
	if (info->serial_signals & SerialSignal_RI)
		strcat(stat_buf, "|RI");

	if (info->params.mode == MGSL_MODE_HDLC) {
		seq_printf(m, " HDLC txok:%d rxok:%d",
			      info->icount.txok, info->icount.rxok);
		if (info->icount.txunder)
			seq_printf(m, " txunder:%d", info->icount.txunder);
		if (info->icount.txabort)
			seq_printf(m, " txabort:%d", info->icount.txabort);
		if (info->icount.rxshort)
			seq_printf(m, " rxshort:%d", info->icount.rxshort);
		if (info->icount.rxlong)
			seq_printf(m, " rxlong:%d", info->icount.rxlong);
		if (info->icount.rxover)
			seq_printf(m, " rxover:%d", info->icount.rxover);
		if (info->icount.rxcrc)
			seq_printf(m, " rxcrc:%d", info->icount.rxcrc);
	} else {
		seq_printf(m, " ASYNC tx:%d rx:%d",
			      info->icount.tx, info->icount.rx);
		if (info->icount.frame)
			seq_printf(m, " fe:%d", info->icount.frame);
		if (info->icount.parity)
			seq_printf(m, " pe:%d", info->icount.parity);
		if (info->icount.brk)
			seq_printf(m, " brk:%d", info->icount.brk);
		if (info->icount.overrun)
			seq_printf(m, " oe:%d", info->icount.overrun);
	}

	/* Append serial signal status to end */
	seq_printf(m, " %s\n", stat_buf+1);

	seq_printf(m, "txactive=%d bh_req=%d bh_run=%d pending_bh=%x\n",
		       info->tx_active,info->bh_requested,info->bh_running,
		       info->pending_bh);
}

/* Called to print information about devices
 */
static int mgslpc_proc_show(struct seq_file *m, void *v)
{
	MGSLPC_INFO *info;

	seq_printf(m, "synclink driver:%s\n", driver_version);

	info = mgslpc_device_list;
	while( info ) {
		line_info(m, info);
		info = info->next_device;
	}
	return 0;
}

static int mgslpc_proc_open(struct inode *inode, struct file *file)
{
	return single_open(file, mgslpc_proc_show, NULL);
}

static const struct file_operations mgslpc_proc_fops = {
	.owner		= THIS_MODULE,
	.open		= mgslpc_proc_open,
	.read		= seq_read,
	.llseek		= seq_lseek,
	.release	= single_release,
};

static int rx_alloc_buffers(MGSLPC_INFO *info)
{
	/* each buffer has header and data */
	info->rx_buf_size = sizeof(RXBUF) + info->max_frame_size;

	/* calculate total allocation size for 8 buffers */
	info->rx_buf_total_size = info->rx_buf_size * 8;

	/* limit total allocated memory */
	if (info->rx_buf_total_size > 0x10000)
		info->rx_buf_total_size = 0x10000;

	/* calculate number of buffers */
	info->rx_buf_count = info->rx_buf_total_size / info->rx_buf_size;

	info->rx_buf = kmalloc(info->rx_buf_total_size, GFP_KERNEL);
	if (info->rx_buf == NULL)
		return -ENOMEM;

	rx_reset_buffers(info);
	return 0;
}

static void rx_free_buffers(MGSLPC_INFO *info)
{
	kfree(info->rx_buf);
	info->rx_buf = NULL;
}

static int claim_resources(MGSLPC_INFO *info)
{
	if (rx_alloc_buffers(info) < 0 ) {
		printk( "Cant allocate rx buffer %s\n", info->device_name);
		release_resources(info);
		return -ENODEV;
	}
	return 0;
}

static void release_resources(MGSLPC_INFO *info)
{
	if (debug_level >= DEBUG_LEVEL_INFO)
		printk("release_resources(%s)\n", info->device_name);
	rx_free_buffers(info);
}

/* Add the specified device instance data structure to the
 * global linked list of devices and increment the device count.
 *
 * Arguments:		info	pointer to device instance data
 */
static void mgslpc_add_device(MGSLPC_INFO *info)
{
	info->next_device = NULL;
	info->line = mgslpc_device_count;
	sprintf(info->device_name,"ttySLP%d",info->line);

	if (info->line < MAX_DEVICE_COUNT) {
		if (maxframe[info->line])
			info->max_frame_size = maxframe[info->line];
	}

	mgslpc_device_count++;

	if (!mgslpc_device_list)
		mgslpc_device_list = info;
	else {
		MGSLPC_INFO *current_dev = mgslpc_device_list;
		while( current_dev->next_device )
			current_dev = current_dev->next_device;
		current_dev->next_device = info;
	}

	if (info->max_frame_size < 4096)
		info->max_frame_size = 4096;
	else if (info->max_frame_size > 65535)
		info->max_frame_size = 65535;

	printk( "SyncLink PC Card %s:IO=%04X IRQ=%d\n",
		info->device_name, info->io_base, info->irq_level);

#if SYNCLINK_GENERIC_HDLC
	hdlcdev_init(info);
#endif
}

static void mgslpc_remove_device(MGSLPC_INFO *remove_info)
{
	MGSLPC_INFO *info = mgslpc_device_list;
	MGSLPC_INFO *last = NULL;

	while(info) {
		if (info == remove_info) {
			if (last)
				last->next_device = info->next_device;
			else
				mgslpc_device_list = info->next_device;
#if SYNCLINK_GENERIC_HDLC
			hdlcdev_exit(info);
#endif
			release_resources(info);
			kfree(info);
			mgslpc_device_count--;
			return;
		}
		last = info;
		info = info->next_device;
	}
}

static struct pcmcia_device_id mgslpc_ids[] = {
	PCMCIA_DEVICE_MANF_CARD(0x02c5, 0x0050),
	PCMCIA_DEVICE_NULL
};
MODULE_DEVICE_TABLE(pcmcia, mgslpc_ids);

static struct pcmcia_driver mgslpc_driver = {
	.owner		= THIS_MODULE,
	.drv		= {
		.name	= "synclink_cs",
	},
	.probe		= mgslpc_probe,
	.remove		= mgslpc_detach,
	.id_table	= mgslpc_ids,
	.suspend	= mgslpc_suspend,
	.resume		= mgslpc_resume,
};

static const struct tty_operations mgslpc_ops = {
	.open = mgslpc_open,
	.close = mgslpc_close,
	.write = mgslpc_write,
	.put_char = mgslpc_put_char,
	.flush_chars = mgslpc_flush_chars,
	.write_room = mgslpc_write_room,
	.chars_in_buffer = mgslpc_chars_in_buffer,
	.flush_buffer = mgslpc_flush_buffer,
	.ioctl = mgslpc_ioctl,
	.throttle = mgslpc_throttle,
	.unthrottle = mgslpc_unthrottle,
	.send_xchar = mgslpc_send_xchar,
	.break_ctl = mgslpc_break,
	.wait_until_sent = mgslpc_wait_until_sent,
	.set_termios = mgslpc_set_termios,
	.stop = tx_pause,
	.start = tx_release,
	.hangup = mgslpc_hangup,
	.tiocmget = tiocmget,
	.tiocmset = tiocmset,
	.proc_fops = &mgslpc_proc_fops,
};

static void synclink_cs_cleanup(void)
{
	int rc;

	printk("Unloading %s: version %s\n", driver_name, driver_version);

	while(mgslpc_device_list)
		mgslpc_remove_device(mgslpc_device_list);

	if (serial_driver) {
		if ((rc = tty_unregister_driver(serial_driver)))
			printk("%s(%d) failed to unregister tty driver err=%d\n",
			       __FILE__,__LINE__,rc);
		put_tty_driver(serial_driver);
	}

	pcmcia_unregister_driver(&mgslpc_driver);
}

static int __init synclink_cs_init(void)
{
    int rc;

    if (break_on_load) {
	    mgslpc_get_text_ptr();
	    BREAKPOINT();
    }

    printk("%s %s\n", driver_name, driver_version);

    if ((rc = pcmcia_register_driver(&mgslpc_driver)) < 0)
	    return rc;

    serial_driver = alloc_tty_driver(MAX_DEVICE_COUNT);
    if (!serial_driver) {
	    rc = -ENOMEM;
	    goto error;
    }

    /* Initialize the tty_driver structure */

    serial_driver->owner = THIS_MODULE;
    serial_driver->driver_name = "synclink_cs";
    serial_driver->name = "ttySLP";
    serial_driver->major = ttymajor;
    serial_driver->minor_start = 64;
    serial_driver->type = TTY_DRIVER_TYPE_SERIAL;
    serial_driver->subtype = SERIAL_TYPE_NORMAL;
    serial_driver->init_termios = tty_std_termios;
    serial_driver->init_termios.c_cflag =
	    B9600 | CS8 | CREAD | HUPCL | CLOCAL;
    serial_driver->flags = TTY_DRIVER_REAL_RAW;
    tty_set_operations(serial_driver, &mgslpc_ops);

    if ((rc = tty_register_driver(serial_driver)) < 0) {
	    printk("%s(%d):Couldn't register serial driver\n",
		   __FILE__,__LINE__);
	    put_tty_driver(serial_driver);
	    serial_driver = NULL;
	    goto error;
    }

    printk("%s %s, tty major#%d\n",
	   driver_name, driver_version,
	   serial_driver->major);

    return 0;

error:
    synclink_cs_cleanup();
    return rc;
}

static void __exit synclink_cs_exit(void)
{
	synclink_cs_cleanup();
}

module_init(synclink_cs_init);
module_exit(synclink_cs_exit);

static void mgslpc_set_rate(MGSLPC_INFO *info, unsigned char channel, unsigned int rate)
{
	unsigned int M, N;
	unsigned char val;

	/* note:standard BRG mode is broken in V3.2 chip
	 * so enhanced mode is always used
	 */

	if (rate) {
		N = 3686400 / rate;
		if (!N)
			N = 1;
		N >>= 1;
		for (M = 1; N > 64 && M < 16; M++)
			N >>= 1;
		N--;

		/* BGR[5..0] = N
		 * BGR[9..6] = M
		 * BGR[7..0] contained in BGR register
		 * BGR[9..8] contained in CCR2[7..6]
		 * divisor = (N+1)*2^M
		 *
		 * Note: M *must* not be zero (causes asymetric duty cycle)
		 */
		write_reg(info, (unsigned char) (channel + BGR),
				  (unsigned char) ((M << 6) + N));
		val = read_reg(info, (unsigned char) (channel + CCR2)) & 0x3f;
		val |= ((M << 4) & 0xc0);
		write_reg(info, (unsigned char) (channel + CCR2), val);
	}
}

/* Enabled the AUX clock output at the specified frequency.
 */
static void enable_auxclk(MGSLPC_INFO *info)
{
	unsigned char val;

	/* MODE
	 *
	 * 07..06  MDS[1..0] 10 = transparent HDLC mode
	 * 05      ADM Address Mode, 0 = no addr recognition
	 * 04      TMD Timer Mode, 0 = external
	 * 03      RAC Receiver Active, 0 = inactive
	 * 02      RTS 0=RTS active during xmit, 1=RTS always active
	 * 01      TRS Timer Resolution, 1=512
	 * 00      TLP Test Loop, 0 = no loop
	 *
	 * 1000 0010
	 */
	val = 0x82;

	/* channel B RTS is used to enable AUXCLK driver on SP505 */
	if (info->params.mode == MGSL_MODE_HDLC && info->params.clock_speed)
		val |= BIT2;
	write_reg(info, CHB + MODE, val);

	/* CCR0
	 *
	 * 07      PU Power Up, 1=active, 0=power down
	 * 06      MCE Master Clock Enable, 1=enabled
	 * 05      Reserved, 0
	 * 04..02  SC[2..0] Encoding
	 * 01..00  SM[1..0] Serial Mode, 00=HDLC
	 *
	 * 11000000
	 */
	write_reg(info, CHB + CCR0, 0xc0);

	/* CCR1
	 *
	 * 07      SFLG Shared Flag, 0 = disable shared flags
	 * 06      GALP Go Active On Loop, 0 = not used
	 * 05      GLP Go On Loop, 0 = not used
	 * 04      ODS Output Driver Select, 1=TxD is push-pull output
	 * 03      ITF Interframe Time Fill, 0=mark, 1=flag
	 * 02..00  CM[2..0] Clock Mode
	 *
	 * 0001 0111
	 */
	write_reg(info, CHB + CCR1, 0x17);

	/* CCR2 (Channel B)
	 *
	 * 07..06  BGR[9..8] Baud rate bits 9..8
	 * 05      BDF Baud rate divisor factor, 0=1, 1=BGR value
	 * 04      SSEL Clock source select, 1=submode b
	 * 03      TOE 0=TxCLK is input, 1=TxCLK is output
	 * 02      RWX Read/Write Exchange 0=disabled
	 * 01      C32, CRC select, 0=CRC-16, 1=CRC-32
	 * 00      DIV, data inversion 0=disabled, 1=enabled
	 *
	 * 0011 1000
	 */
	if (info->params.mode == MGSL_MODE_HDLC && info->params.clock_speed)
		write_reg(info, CHB + CCR2, 0x38);
	else
		write_reg(info, CHB + CCR2, 0x30);

	/* CCR4
	 *
	 * 07      MCK4 Master Clock Divide by 4, 1=enabled
	 * 06      EBRG Enhanced Baud Rate Generator Mode, 1=enabled
	 * 05      TST1 Test Pin, 0=normal operation
	 * 04      ICD Ivert Carrier Detect, 1=enabled (active low)
	 * 03..02  Reserved, must be 0
	 * 01..00  RFT[1..0] RxFIFO Threshold 00=32 bytes
	 *
	 * 0101 0000
	 */
	write_reg(info, CHB + CCR4, 0x50);

	/* if auxclk not enabled, set internal BRG so
	 * CTS transitions can be detected (requires TxC)
	 */
	if (info->params.mode == MGSL_MODE_HDLC && info->params.clock_speed)
		mgslpc_set_rate(info, CHB, info->params.clock_speed);
	else
		mgslpc_set_rate(info, CHB, 921600);
}

static void loopback_enable(MGSLPC_INFO *info)
{
	unsigned char val;

	/* CCR1:02..00  CM[2..0] Clock Mode = 111 (clock mode 7) */
	val = read_reg(info, CHA + CCR1) | (BIT2 + BIT1 + BIT0);
	write_reg(info, CHA + CCR1, val);

	/* CCR2:04 SSEL Clock source select, 1=submode b */
	val = read_reg(info, CHA + CCR2) | (BIT4 + BIT5);
	write_reg(info, CHA + CCR2, val);

	/* set LinkSpeed if available, otherwise default to 2Mbps */
	if (info->params.clock_speed)
		mgslpc_set_rate(info, CHA, info->params.clock_speed);
	else
		mgslpc_set_rate(info, CHA, 1843200);

	/* MODE:00 TLP Test Loop, 1=loopback enabled */
	val = read_reg(info, CHA + MODE) | BIT0;
	write_reg(info, CHA + MODE, val);
}

static void hdlc_mode(MGSLPC_INFO *info)
{
	unsigned char val;
	unsigned char clkmode, clksubmode;

	/* disable all interrupts */
	irq_disable(info, CHA, 0xffff);
	irq_disable(info, CHB, 0xffff);
	port_irq_disable(info, 0xff);

	/* assume clock mode 0a, rcv=RxC xmt=TxC */
	clkmode = clksubmode = 0;
	if (info->params.flags & HDLC_FLAG_RXC_DPLL
	    && info->params.flags & HDLC_FLAG_TXC_DPLL) {
		/* clock mode 7a, rcv = DPLL, xmt = DPLL */
		clkmode = 7;
	} else if (info->params.flags & HDLC_FLAG_RXC_BRG
		 && info->params.flags & HDLC_FLAG_TXC_BRG) {
		/* clock mode 7b, rcv = BRG, xmt = BRG */
		clkmode = 7;
		clksubmode = 1;
	} else if (info->params.flags & HDLC_FLAG_RXC_DPLL) {
		if (info->params.flags & HDLC_FLAG_TXC_BRG) {
			/* clock mode 6b, rcv = DPLL, xmt = BRG/16 */
			clkmode = 6;
			clksubmode = 1;
		} else {
			/* clock mode 6a, rcv = DPLL, xmt = TxC */
			clkmode = 6;
		}
	} else if (info->params.flags & HDLC_FLAG_TXC_BRG) {
		/* clock mode 0b, rcv = RxC, xmt = BRG */
		clksubmode = 1;
	}

	/* MODE
	 *
	 * 07..06  MDS[1..0] 10 = transparent HDLC mode
	 * 05      ADM Address Mode, 0 = no addr recognition
	 * 04      TMD Timer Mode, 0 = external
	 * 03      RAC Receiver Active, 0 = inactive
	 * 02      RTS 0=RTS active during xmit, 1=RTS always active
	 * 01      TRS Timer Resolution, 1=512
	 * 00      TLP Test Loop, 0 = no loop
	 *
	 * 1000 0010
	 */
	val = 0x82;
	if (info->params.loopback)
		val |= BIT0;

	/* preserve RTS state */
	if (info->serial_signals & SerialSignal_RTS)
		val |= BIT2;
	write_reg(info, CHA + MODE, val);

	/* CCR0
	 *
	 * 07      PU Power Up, 1=active, 0=power down
	 * 06      MCE Master Clock Enable, 1=enabled
	 * 05      Reserved, 0
	 * 04..02  SC[2..0] Encoding
	 * 01..00  SM[1..0] Serial Mode, 00=HDLC
	 *
	 * 11000000
	 */
	val = 0xc0;
	switch (info->params.encoding)
	{
	case HDLC_ENCODING_NRZI:
		val |= BIT3;
		break;
	case HDLC_ENCODING_BIPHASE_SPACE:
		val |= BIT4;
		break;		// FM0
	case HDLC_ENCODING_BIPHASE_MARK:
		val |= BIT4 + BIT2;
		break;		// FM1
	case HDLC_ENCODING_BIPHASE_LEVEL:
		val |= BIT4 + BIT3;
		break;		// Manchester
	}
	write_reg(info, CHA + CCR0, val);

	/* CCR1
	 *
	 * 07      SFLG Shared Flag, 0 = disable shared flags
	 * 06      GALP Go Active On Loop, 0 = not used
	 * 05      GLP Go On Loop, 0 = not used
	 * 04      ODS Output Driver Select, 1=TxD is push-pull output
	 * 03      ITF Interframe Time Fill, 0=mark, 1=flag
	 * 02..00  CM[2..0] Clock Mode
	 *
	 * 0001 0000
	 */
	val = 0x10 + clkmode;
	write_reg(info, CHA + CCR1, val);

	/* CCR2
	 *
	 * 07..06  BGR[9..8] Baud rate bits 9..8
	 * 05      BDF Baud rate divisor factor, 0=1, 1=BGR value
	 * 04      SSEL Clock source select, 1=submode b
	 * 03      TOE 0=TxCLK is input, 0=TxCLK is input
	 * 02      RWX Read/Write Exchange 0=disabled
	 * 01      C32, CRC select, 0=CRC-16, 1=CRC-32
	 * 00      DIV, data inversion 0=disabled, 1=enabled
	 *
	 * 0000 0000
	 */
	val = 0x00;
	if (clkmode == 2 || clkmode == 3 || clkmode == 6
	    || clkmode == 7 || (clkmode == 0 && clksubmode == 1))
		val |= BIT5;
	if (clksubmode)
		val |= BIT4;
	if (info->params.crc_type == HDLC_CRC_32_CCITT)
		val |= BIT1;
	if (info->params.encoding == HDLC_ENCODING_NRZB)
		val |= BIT0;
	write_reg(info, CHA + CCR2, val);

	/* CCR3
	 *
	 * 07..06  PRE[1..0] Preamble count 00=1, 01=2, 10=4, 11=8
	 * 05      EPT Enable preamble transmission, 1=enabled
	 * 04      RADD Receive address pushed to FIFO, 0=disabled
	 * 03      CRL CRC Reset Level, 0=FFFF
	 * 02      RCRC Rx CRC 0=On 1=Off
	 * 01      TCRC Tx CRC 0=On 1=Off
	 * 00      PSD DPLL Phase Shift Disable
	 *
	 * 0000 0000
	 */
	val = 0x00;
	if (info->params.crc_type == HDLC_CRC_NONE)
		val |= BIT2 + BIT1;
	if (info->params.preamble != HDLC_PREAMBLE_PATTERN_NONE)
		val |= BIT5;
	switch (info->params.preamble_length)
	{
	case HDLC_PREAMBLE_LENGTH_16BITS:
		val |= BIT6;
		break;
	case HDLC_PREAMBLE_LENGTH_32BITS:
		val |= BIT6;
		break;
	case HDLC_PREAMBLE_LENGTH_64BITS:
		val |= BIT7 + BIT6;
		break;
	}
	write_reg(info, CHA + CCR3, val);

	/* PRE - Preamble pattern */
	val = 0;
	switch (info->params.preamble)
	{
	case HDLC_PREAMBLE_PATTERN_FLAGS: val = 0x7e; break;
	case HDLC_PREAMBLE_PATTERN_10:    val = 0xaa; break;
	case HDLC_PREAMBLE_PATTERN_01:    val = 0x55; break;
	case HDLC_PREAMBLE_PATTERN_ONES:  val = 0xff; break;
	}
	write_reg(info, CHA + PRE, val);

	/* CCR4
	 *
	 * 07      MCK4 Master Clock Divide by 4, 1=enabled
	 * 06      EBRG Enhanced Baud Rate Generator Mode, 1=enabled
	 * 05      TST1 Test Pin, 0=normal operation
	 * 04      ICD Ivert Carrier Detect, 1=enabled (active low)
	 * 03..02  Reserved, must be 0
	 * 01..00  RFT[1..0] RxFIFO Threshold 00=32 bytes
	 *
	 * 0101 0000
	 */
	val = 0x50;
	write_reg(info, CHA + CCR4, val);
	if (info->params.flags & HDLC_FLAG_RXC_DPLL)
		mgslpc_set_rate(info, CHA, info->params.clock_speed * 16);
	else
		mgslpc_set_rate(info, CHA, info->params.clock_speed);

	/* RLCR Receive length check register
	 *
	 * 7     1=enable receive length check
	 * 6..0  Max frame length = (RL + 1) * 32
	 */
	write_reg(info, CHA + RLCR, 0);

	/* XBCH Transmit Byte Count High
	 *
	 * 07      DMA mode, 0 = interrupt driven
	 * 06      NRM, 0=ABM (ignored)
	 * 05      CAS Carrier Auto Start
	 * 04      XC Transmit Continuously (ignored)
	 * 03..00  XBC[10..8] Transmit byte count bits 10..8
	 *
	 * 0000 0000
	 */
	val = 0x00;
	if (info->params.flags & HDLC_FLAG_AUTO_DCD)
		val |= BIT5;
	write_reg(info, CHA + XBCH, val);
	enable_auxclk(info);
	if (info->params.loopback || info->testing_irq)
		loopback_enable(info);
	if (info->params.flags & HDLC_FLAG_AUTO_CTS)
	{
		irq_enable(info, CHB, IRQ_CTS);
		/* PVR[3] 1=AUTO CTS active */
		set_reg_bits(info, CHA + PVR, BIT3);
	} else
		clear_reg_bits(info, CHA + PVR, BIT3);

	irq_enable(info, CHA,
			 IRQ_RXEOM + IRQ_RXFIFO + IRQ_ALLSENT +
			 IRQ_UNDERRUN + IRQ_TXFIFO);
	issue_command(info, CHA, CMD_TXRESET + CMD_RXRESET);
	wait_command_complete(info, CHA);
	read_reg16(info, CHA + ISR);	/* clear pending IRQs */

	/* Master clock mode enabled above to allow reset commands
	 * to complete even if no data clocks are present.
	 *
	 * Disable master clock mode for normal communications because
	 * V3.2 of the ESCC2 has a bug that prevents the transmit all sent
	 * IRQ when in master clock mode.
	 *
	 * Leave master clock mode enabled for IRQ test because the
	 * timer IRQ used by the test can only happen in master clock mode.
	 */
	if (!info->testing_irq)
		clear_reg_bits(info, CHA + CCR0, BIT6);

	tx_set_idle(info);

	tx_stop(info);
	rx_stop(info);
}

static void rx_stop(MGSLPC_INFO *info)
{
	if (debug_level >= DEBUG_LEVEL_ISR)
		printk("%s(%d):rx_stop(%s)\n",
			 __FILE__,__LINE__, info->device_name );

	/* MODE:03 RAC Receiver Active, 0=inactive */
	clear_reg_bits(info, CHA + MODE, BIT3);

	info->rx_enabled = false;
	info->rx_overflow = false;
}

static void rx_start(MGSLPC_INFO *info)
{
	if (debug_level >= DEBUG_LEVEL_ISR)
		printk("%s(%d):rx_start(%s)\n",
			 __FILE__,__LINE__, info->device_name );

	rx_reset_buffers(info);
	info->rx_enabled = false;
	info->rx_overflow = false;

	/* MODE:03 RAC Receiver Active, 1=active */
	set_reg_bits(info, CHA + MODE, BIT3);

	info->rx_enabled = true;
}

static void tx_start(MGSLPC_INFO *info, struct tty_struct *tty)
{
	if (debug_level >= DEBUG_LEVEL_ISR)
		printk("%s(%d):tx_start(%s)\n",
			 __FILE__,__LINE__, info->device_name );

	if (info->tx_count) {
		/* If auto RTS enabled and RTS is inactive, then assert */
		/* RTS and set a flag indicating that the driver should */
		/* negate RTS when the transmission completes. */
		info->drop_rts_on_tx_done = false;

		if (info->params.flags & HDLC_FLAG_AUTO_RTS) {
			get_signals(info);
			if (!(info->serial_signals & SerialSignal_RTS)) {
				info->serial_signals |= SerialSignal_RTS;
				set_signals(info);
				info->drop_rts_on_tx_done = true;
			}
		}

		if (info->params.mode == MGSL_MODE_ASYNC) {
			if (!info->tx_active) {
				info->tx_active = true;
				tx_ready(info, tty);
			}
		} else {
			info->tx_active = true;
			tx_ready(info, tty);
			mod_timer(&info->tx_timer, jiffies +
					msecs_to_jiffies(5000));
		}
	}

	if (!info->tx_enabled)
		info->tx_enabled = true;
}

static void tx_stop(MGSLPC_INFO *info)
{
	if (debug_level >= DEBUG_LEVEL_ISR)
		printk("%s(%d):tx_stop(%s)\n",
			 __FILE__,__LINE__, info->device_name );

	del_timer(&info->tx_timer);

	info->tx_enabled = false;
	info->tx_active = false;
}

/* Reset the adapter to a known state and prepare it for further use.
 */
static void reset_device(MGSLPC_INFO *info)
{
	/* power up both channels (set BIT7) */
	write_reg(info, CHA + CCR0, 0x80);
	write_reg(info, CHB + CCR0, 0x80);
	write_reg(info, CHA + MODE, 0);
	write_reg(info, CHB + MODE, 0);

	/* disable all interrupts */
	irq_disable(info, CHA, 0xffff);
	irq_disable(info, CHB, 0xffff);
	port_irq_disable(info, 0xff);

	/* PCR Port Configuration Register
	 *
	 * 07..04  DEC[3..0] Serial I/F select outputs
	 * 03      output, 1=AUTO CTS control enabled
	 * 02      RI Ring Indicator input 0=active
	 * 01      DSR input 0=active
	 * 00      DTR output 0=active
	 *
	 * 0000 0110
	 */
	write_reg(info, PCR, 0x06);

	/* PVR Port Value Register
	 *
	 * 07..04  DEC[3..0] Serial I/F select (0000=disabled)
	 * 03      AUTO CTS output 1=enabled
	 * 02      RI Ring Indicator input
	 * 01      DSR input
	 * 00      DTR output (1=inactive)
	 *
	 * 0000 0001
	 */
//	write_reg(info, PVR, PVR_DTR);

	/* IPC Interrupt Port Configuration
	 *
	 * 07      VIS 1=Masked interrupts visible
	 * 06..05  Reserved, 0
	 * 04..03  SLA Slave address, 00 ignored
	 * 02      CASM Cascading Mode, 1=daisy chain
	 * 01..00  IC[1..0] Interrupt Config, 01=push-pull output, active low
	 *
	 * 0000 0101
	 */
	write_reg(info, IPC, 0x05);
}

static void async_mode(MGSLPC_INFO *info)
{
	unsigned char val;

	/* disable all interrupts */
	irq_disable(info, CHA, 0xffff);
	irq_disable(info, CHB, 0xffff);
	port_irq_disable(info, 0xff);

	/* MODE
	 *
	 * 07      Reserved, 0
	 * 06      FRTS RTS State, 0=active
	 * 05      FCTS Flow Control on CTS
	 * 04      FLON Flow Control Enable
	 * 03      RAC Receiver Active, 0 = inactive
	 * 02      RTS 0=Auto RTS, 1=manual RTS
	 * 01      TRS Timer Resolution, 1=512
	 * 00      TLP Test Loop, 0 = no loop
	 *
	 * 0000 0110
	 */
	val = 0x06;
	if (info->params.loopback)
		val |= BIT0;

	/* preserve RTS state */
	if (!(info->serial_signals & SerialSignal_RTS))
		val |= BIT6;
	write_reg(info, CHA + MODE, val);

	/* CCR0
	 *
	 * 07      PU Power Up, 1=active, 0=power down
	 * 06      MCE Master Clock Enable, 1=enabled
	 * 05      Reserved, 0
	 * 04..02  SC[2..0] Encoding, 000=NRZ
	 * 01..00  SM[1..0] Serial Mode, 11=Async
	 *
	 * 1000 0011
	 */
	write_reg(info, CHA + CCR0, 0x83);

	/* CCR1
	 *
	 * 07..05  Reserved, 0
	 * 04      ODS Output Driver Select, 1=TxD is push-pull output
	 * 03      BCR Bit Clock Rate, 1=16x
	 * 02..00  CM[2..0] Clock Mode, 111=BRG
	 *
	 * 0001 1111
	 */
	write_reg(info, CHA + CCR1, 0x1f);

	/* CCR2 (channel A)
	 *
	 * 07..06  BGR[9..8] Baud rate bits 9..8
	 * 05      BDF Baud rate divisor factor, 0=1, 1=BGR value
	 * 04      SSEL Clock source select, 1=submode b
	 * 03      TOE 0=TxCLK is input, 0=TxCLK is input
	 * 02      RWX Read/Write Exchange 0=disabled
	 * 01      Reserved, 0
	 * 00      DIV, data inversion 0=disabled, 1=enabled
	 *
	 * 0001 0000
	 */
	write_reg(info, CHA + CCR2, 0x10);

	/* CCR3
	 *
	 * 07..01  Reserved, 0
	 * 00      PSD DPLL Phase Shift Disable
	 *
	 * 0000 0000
	 */
	write_reg(info, CHA + CCR3, 0);

	/* CCR4
	 *
	 * 07      MCK4 Master Clock Divide by 4, 1=enabled
	 * 06      EBRG Enhanced Baud Rate Generator Mode, 1=enabled
	 * 05      TST1 Test Pin, 0=normal operation
	 * 04      ICD Ivert Carrier Detect, 1=enabled (active low)
	 * 03..00  Reserved, must be 0
	 *
	 * 0101 0000
	 */
	write_reg(info, CHA + CCR4, 0x50);
	mgslpc_set_rate(info, CHA, info->params.data_rate * 16);

	/* DAFO Data Format
	 *
	 * 07      Reserved, 0
	 * 06      XBRK transmit break, 0=normal operation
	 * 05      Stop bits (0=1, 1=2)
	 * 04..03  PAR[1..0] Parity (01=odd, 10=even)
	 * 02      PAREN Parity Enable
	 * 01..00  CHL[1..0] Character Length (00=8, 01=7)
	 *
	 */
	val = 0x00;
	if (info->params.data_bits != 8)
		val |= BIT0;	/* 7 bits */
	if (info->params.stop_bits != 1)
		val |= BIT5;
	if (info->params.parity != ASYNC_PARITY_NONE)
	{
		val |= BIT2;	/* Parity enable */
		if (info->params.parity == ASYNC_PARITY_ODD)
			val |= BIT3;
		else
			val |= BIT4;
	}
	write_reg(info, CHA + DAFO, val);

	/* RFC Rx FIFO Control
	 *
	 * 07      Reserved, 0
	 * 06      DPS, 1=parity bit not stored in data byte
	 * 05      DXS, 0=all data stored in FIFO (including XON/XOFF)
	 * 04      RFDF Rx FIFO Data Format, 1=status byte stored in FIFO
	 * 03..02  RFTH[1..0], rx threshold, 11=16 status + 16 data byte
	 * 01      Reserved, 0
	 * 00      TCDE Terminate Char Detect Enable, 0=disabled
	 *
	 * 0101 1100
	 */
	write_reg(info, CHA + RFC, 0x5c);

	/* RLCR Receive length check register
	 *
	 * Max frame length = (RL + 1) * 32
	 */
	write_reg(info, CHA + RLCR, 0);

	/* XBCH Transmit Byte Count High
	 *
	 * 07      DMA mode, 0 = interrupt driven
	 * 06      NRM, 0=ABM (ignored)
	 * 05      CAS Carrier Auto Start
	 * 04      XC Transmit Continuously (ignored)
	 * 03..00  XBC[10..8] Transmit byte count bits 10..8
	 *
	 * 0000 0000
	 */
	val = 0x00;
	if (info->params.flags & HDLC_FLAG_AUTO_DCD)
		val |= BIT5;
	write_reg(info, CHA + XBCH, val);
	if (info->params.flags & HDLC_FLAG_AUTO_CTS)
		irq_enable(info, CHA, IRQ_CTS);

	/* MODE:03 RAC Receiver Active, 1=active */
	set_reg_bits(info, CHA + MODE, BIT3);
	enable_auxclk(info);
	if (info->params.flags & HDLC_FLAG_AUTO_CTS) {
		irq_enable(info, CHB, IRQ_CTS);
		/* PVR[3] 1=AUTO CTS active */
		set_reg_bits(info, CHA + PVR, BIT3);
	} else
		clear_reg_bits(info, CHA + PVR, BIT3);
	irq_enable(info, CHA,
			  IRQ_RXEOM + IRQ_RXFIFO + IRQ_BREAK_ON + IRQ_RXTIME +
			  IRQ_ALLSENT + IRQ_TXFIFO);
	issue_command(info, CHA, CMD_TXRESET + CMD_RXRESET);
	wait_command_complete(info, CHA);
	read_reg16(info, CHA + ISR);	/* clear pending IRQs */
}

/* Set the HDLC idle mode for the transmitter.
 */
static void tx_set_idle(MGSLPC_INFO *info)
{
	/* Note: ESCC2 only supports flags and one idle modes */
	if (info->idle_mode == HDLC_TXIDLE_FLAGS)
		set_reg_bits(info, CHA + CCR1, BIT3);
	else
		clear_reg_bits(info, CHA + CCR1, BIT3);
}

/* get state of the V24 status (input) signals.
 */
static void get_signals(MGSLPC_INFO *info)
{
	unsigned char status = 0;

	/* preserve DTR and RTS */
	info->serial_signals &= SerialSignal_DTR + SerialSignal_RTS;

	if (read_reg(info, CHB + VSTR) & BIT7)
		info->serial_signals |= SerialSignal_DCD;
	if (read_reg(info, CHB + STAR) & BIT1)
		info->serial_signals |= SerialSignal_CTS;

	status = read_reg(info, CHA + PVR);
	if (!(status & PVR_RI))
		info->serial_signals |= SerialSignal_RI;
	if (!(status & PVR_DSR))
		info->serial_signals |= SerialSignal_DSR;
}

/* Set the state of DTR and RTS based on contents of
 * serial_signals member of device extension.
 */
static void set_signals(MGSLPC_INFO *info)
{
	unsigned char val;

	val = read_reg(info, CHA + MODE);
	if (info->params.mode == MGSL_MODE_ASYNC) {
		if (info->serial_signals & SerialSignal_RTS)
			val &= ~BIT6;
		else
			val |= BIT6;
	} else {
		if (info->serial_signals & SerialSignal_RTS)
			val |= BIT2;
		else
			val &= ~BIT2;
	}
	write_reg(info, CHA + MODE, val);

	if (info->serial_signals & SerialSignal_DTR)
		clear_reg_bits(info, CHA + PVR, PVR_DTR);
	else
		set_reg_bits(info, CHA + PVR, PVR_DTR);
}

static void rx_reset_buffers(MGSLPC_INFO *info)
{
	RXBUF *buf;
	int i;

	info->rx_put = 0;
	info->rx_get = 0;
	info->rx_frame_count = 0;
	for (i=0 ; i < info->rx_buf_count ; i++) {
		buf = (RXBUF*)(info->rx_buf + (i * info->rx_buf_size));
		buf->status = buf->count = 0;
	}
}

/* Attempt to return a received HDLC frame
 * Only frames received without errors are returned.
 *
 * Returns true if frame returned, otherwise false
 */
static bool rx_get_frame(MGSLPC_INFO *info, struct tty_struct *tty)
{
	unsigned short status;
	RXBUF *buf;
	unsigned int framesize = 0;
	unsigned long flags;
	bool return_frame = false;

	if (info->rx_frame_count == 0)
		return false;

	buf = (RXBUF*)(info->rx_buf + (info->rx_get * info->rx_buf_size));

	status = buf->status;

	/* 07  VFR  1=valid frame
	 * 06  RDO  1=data overrun
	 * 05  CRC  1=OK, 0=error
	 * 04  RAB  1=frame aborted
	 */
	if ((status & 0xf0) != 0xA0) {
		if (!(status & BIT7) || (status & BIT4))
			info->icount.rxabort++;
		else if (status & BIT6)
			info->icount.rxover++;
		else if (!(status & BIT5)) {
			info->icount.rxcrc++;
			if (info->params.crc_type & HDLC_CRC_RETURN_EX)
				return_frame = true;
		}
		framesize = 0;
#if SYNCLINK_GENERIC_HDLC
		{
			info->netdev->stats.rx_errors++;
			info->netdev->stats.rx_frame_errors++;
		}
#endif
	} else
		return_frame = true;

	if (return_frame)
		framesize = buf->count;

	if (debug_level >= DEBUG_LEVEL_BH)
		printk("%s(%d):rx_get_frame(%s) status=%04X size=%d\n",
			__FILE__,__LINE__,info->device_name,status,framesize);

	if (debug_level >= DEBUG_LEVEL_DATA)
		trace_block(info, buf->data, framesize, 0);

	if (framesize) {
		if ((info->params.crc_type & HDLC_CRC_RETURN_EX &&
		      framesize+1 > info->max_frame_size) ||
		    framesize > info->max_frame_size)
			info->icount.rxlong++;
		else {
			if (status & BIT5)
				info->icount.rxok++;

			if (info->params.crc_type & HDLC_CRC_RETURN_EX) {
				*(buf->data + framesize) = status & BIT5 ? RX_OK:RX_CRC_ERROR;
				++framesize;
			}

#if SYNCLINK_GENERIC_HDLC
			if (info->netcount)
				hdlcdev_rx(info, buf->data, framesize);
			else
#endif
				ldisc_receive_buf(tty, buf->data, info->flag_buf, framesize);
		}
	}

	spin_lock_irqsave(&info->lock,flags);
	buf->status = buf->count = 0;
	info->rx_frame_count--;
	info->rx_get++;
	if (info->rx_get >= info->rx_buf_count)
		info->rx_get = 0;
	spin_unlock_irqrestore(&info->lock,flags);

	return true;
}

static bool register_test(MGSLPC_INFO *info)
{
	static unsigned char patterns[] =
	    { 0x00, 0xff, 0xaa, 0x55, 0x69, 0x96, 0x0f };
	static unsigned int count = ARRAY_SIZE(patterns);
	unsigned int i;
	bool rc = true;
	unsigned long flags;

	spin_lock_irqsave(&info->lock,flags);
	reset_device(info);

	for (i = 0; i < count; i++) {
		write_reg(info, XAD1, patterns[i]);
		write_reg(info, XAD2, patterns[(i + 1) % count]);
		if ((read_reg(info, XAD1) != patterns[i]) ||
		    (read_reg(info, XAD2) != patterns[(i + 1) % count])) {
			rc = false;
			break;
		}
	}

	spin_unlock_irqrestore(&info->lock,flags);
	return rc;
}

static bool irq_test(MGSLPC_INFO *info)
{
	unsigned long end_time;
	unsigned long flags;

	spin_lock_irqsave(&info->lock,flags);
	reset_device(info);

	info->testing_irq = true;
	hdlc_mode(info);

	info->irq_occurred = false;

	/* init hdlc mode */

	irq_enable(info, CHA, IRQ_TIMER);
	write_reg(info, CHA + TIMR, 0);	/* 512 cycles */
	issue_command(info, CHA, CMD_START_TIMER);

	spin_unlock_irqrestore(&info->lock,flags);

	end_time=100;
	while(end_time-- && !info->irq_occurred) {
		msleep_interruptible(10);
	}

	info->testing_irq = false;

	spin_lock_irqsave(&info->lock,flags);
	reset_device(info);
	spin_unlock_irqrestore(&info->lock,flags);

	return info->irq_occurred;
}

static int adapter_test(MGSLPC_INFO *info)
{
	if (!register_test(info)) {
		info->init_error = DiagStatus_AddressFailure;
		printk( "%s(%d):Register test failure for device %s Addr=%04X\n",
			__FILE__,__LINE__,info->device_name, (unsigned short)(info->io_base) );
		return -ENODEV;
	}

	if (!irq_test(info)) {
		info->init_error = DiagStatus_IrqFailure;
		printk( "%s(%d):Interrupt test failure for device %s IRQ=%d\n",
			__FILE__,__LINE__,info->device_name, (unsigned short)(info->irq_level) );
		return -ENODEV;
	}

	if (debug_level >= DEBUG_LEVEL_INFO)
		printk("%s(%d):device %s passed diagnostics\n",
			__FILE__,__LINE__,info->device_name);
	return 0;
}

static void trace_block(MGSLPC_INFO *info,const char* data, int count, int xmit)
{
	int i;
	int linecount;
	if (xmit)
		printk("%s tx data:\n",info->device_name);
	else
		printk("%s rx data:\n",info->device_name);

	while(count) {
		if (count > 16)
			linecount = 16;
		else
			linecount = count;

		for(i=0;i<linecount;i++)
			printk("%02X ",(unsigned char)data[i]);
		for(;i<17;i++)
			printk("   ");
		for(i=0;i<linecount;i++) {
			if (data[i]>=040 && data[i]<=0176)
				printk("%c",data[i]);
			else
				printk(".");
		}
		printk("\n");

		data  += linecount;
		count -= linecount;
	}
}

/* HDLC frame time out
 * update stats and do tx completion processing
 */
static void tx_timeout(unsigned long context)
{
	MGSLPC_INFO *info = (MGSLPC_INFO*)context;
	unsigned long flags;

	if ( debug_level >= DEBUG_LEVEL_INFO )
		printk( "%s(%d):tx_timeout(%s)\n",
			__FILE__,__LINE__,info->device_name);
	if(info->tx_active &&
	   info->params.mode == MGSL_MODE_HDLC) {
		info->icount.txtimeout++;
	}
	spin_lock_irqsave(&info->lock,flags);
	info->tx_active = false;
	info->tx_count = info->tx_put = info->tx_get = 0;

	spin_unlock_irqrestore(&info->lock,flags);

#if SYNCLINK_GENERIC_HDLC
	if (info->netcount)
		hdlcdev_tx_done(info);
	else
#endif
	{
		struct tty_struct *tty = tty_port_tty_get(&info->port);
		bh_transmit(info, tty);
		tty_kref_put(tty);
	}
}

#if SYNCLINK_GENERIC_HDLC

/**
 * called by generic HDLC layer when protocol selected (PPP, frame relay, etc.)
 * set encoding and frame check sequence (FCS) options
 *
 * dev       pointer to network device structure
 * encoding  serial encoding setting
 * parity    FCS setting
 *
 * returns 0 if success, otherwise error code
 */
static int hdlcdev_attach(struct net_device *dev, unsigned short encoding,
			  unsigned short parity)
{
	MGSLPC_INFO *info = dev_to_port(dev);
	struct tty_struct *tty;
	unsigned char  new_encoding;
	unsigned short new_crctype;

	/* return error if TTY interface open */
	if (info->port.count)
		return -EBUSY;

	switch (encoding)
	{
	case ENCODING_NRZ:        new_encoding = HDLC_ENCODING_NRZ; break;
	case ENCODING_NRZI:       new_encoding = HDLC_ENCODING_NRZI_SPACE; break;
	case ENCODING_FM_MARK:    new_encoding = HDLC_ENCODING_BIPHASE_MARK; break;
	case ENCODING_FM_SPACE:   new_encoding = HDLC_ENCODING_BIPHASE_SPACE; break;
	case ENCODING_MANCHESTER: new_encoding = HDLC_ENCODING_BIPHASE_LEVEL; break;
	default: return -EINVAL;
	}

	switch (parity)
	{
	case PARITY_NONE:            new_crctype = HDLC_CRC_NONE; break;
	case PARITY_CRC16_PR1_CCITT: new_crctype = HDLC_CRC_16_CCITT; break;
	case PARITY_CRC32_PR1_CCITT: new_crctype = HDLC_CRC_32_CCITT; break;
	default: return -EINVAL;
	}

	info->params.encoding = new_encoding;
	info->params.crc_type = new_crctype;

	/* if network interface up, reprogram hardware */
	if (info->netcount) {
		tty = tty_port_tty_get(&info->port);
		mgslpc_program_hw(info, tty);
		tty_kref_put(tty);
	}

	return 0;
}

/**
 * called by generic HDLC layer to send frame
 *
 * skb  socket buffer containing HDLC frame
 * dev  pointer to network device structure
 */
static netdev_tx_t hdlcdev_xmit(struct sk_buff *skb,
				      struct net_device *dev)
{
	MGSLPC_INFO *info = dev_to_port(dev);
	unsigned long flags;

	if (debug_level >= DEBUG_LEVEL_INFO)
		printk(KERN_INFO "%s:hdlc_xmit(%s)\n",__FILE__,dev->name);

	/* stop sending until this frame completes */
	netif_stop_queue(dev);

	/* copy data to device buffers */
	skb_copy_from_linear_data(skb, info->tx_buf, skb->len);
	info->tx_get = 0;
	info->tx_put = info->tx_count = skb->len;

	/* update network statistics */
	dev->stats.tx_packets++;
	dev->stats.tx_bytes += skb->len;

	/* done with socket buffer, so free it */
	dev_kfree_skb(skb);

	/* save start time for transmit timeout detection */
	dev->trans_start = jiffies;

	/* start hardware transmitter if necessary */
	spin_lock_irqsave(&info->lock,flags);
	if (!info->tx_active) {
		struct tty_struct *tty = tty_port_tty_get(&info->port);
	 	tx_start(info, tty);
	 	tty_kref_put(tty);
	}
	spin_unlock_irqrestore(&info->lock,flags);

	return NETDEV_TX_OK;
}

/**
 * called by network layer when interface enabled
 * claim resources and initialize hardware
 *
 * dev  pointer to network device structure
 *
 * returns 0 if success, otherwise error code
 */
static int hdlcdev_open(struct net_device *dev)
{
	MGSLPC_INFO *info = dev_to_port(dev);
	struct tty_struct *tty;
	int rc;
	unsigned long flags;

	if (debug_level >= DEBUG_LEVEL_INFO)
		printk("%s:hdlcdev_open(%s)\n",__FILE__,dev->name);

	/* generic HDLC layer open processing */
	if ((rc = hdlc_open(dev)))
		return rc;

	/* arbitrate between network and tty opens */
	spin_lock_irqsave(&info->netlock, flags);
	if (info->port.count != 0 || info->netcount != 0) {
		printk(KERN_WARNING "%s: hdlc_open returning busy\n", dev->name);
		spin_unlock_irqrestore(&info->netlock, flags);
		return -EBUSY;
	}
	info->netcount=1;
	spin_unlock_irqrestore(&info->netlock, flags);

	tty = tty_port_tty_get(&info->port);
	/* claim resources and init adapter */
	if ((rc = startup(info, tty)) != 0) {
		tty_kref_put(tty);
		spin_lock_irqsave(&info->netlock, flags);
		info->netcount=0;
		spin_unlock_irqrestore(&info->netlock, flags);
		return rc;
	}
	/* assert DTR and RTS, apply hardware settings */
	info->serial_signals |= SerialSignal_RTS + SerialSignal_DTR;
	mgslpc_program_hw(info, tty);
	tty_kref_put(tty);

	/* enable network layer transmit */
	dev->trans_start = jiffies;
	netif_start_queue(dev);

	/* inform generic HDLC layer of current DCD status */
	spin_lock_irqsave(&info->lock, flags);
	get_signals(info);
	spin_unlock_irqrestore(&info->lock, flags);
	if (info->serial_signals & SerialSignal_DCD)
		netif_carrier_on(dev);
	else
		netif_carrier_off(dev);
	return 0;
}

/**
 * called by network layer when interface is disabled
 * shutdown hardware and release resources
 *
 * dev  pointer to network device structure
 *
 * returns 0 if success, otherwise error code
 */
static int hdlcdev_close(struct net_device *dev)
{
	MGSLPC_INFO *info = dev_to_port(dev);
	struct tty_struct *tty = tty_port_tty_get(&info->port);
	unsigned long flags;

	if (debug_level >= DEBUG_LEVEL_INFO)
		printk("%s:hdlcdev_close(%s)\n",__FILE__,dev->name);

	netif_stop_queue(dev);

	/* shutdown adapter and release resources */
	shutdown(info, tty);
	tty_kref_put(tty);
	hdlc_close(dev);

	spin_lock_irqsave(&info->netlock, flags);
	info->netcount=0;
	spin_unlock_irqrestore(&info->netlock, flags);

	return 0;
}

/**
 * called by network layer to process IOCTL call to network device
 *
 * dev  pointer to network device structure
 * ifr  pointer to network interface request structure
 * cmd  IOCTL command code
 *
 * returns 0 if success, otherwise error code
 */
static int hdlcdev_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
{
	const size_t size = sizeof(sync_serial_settings);
	sync_serial_settings new_line;
	sync_serial_settings __user *line = ifr->ifr_settings.ifs_ifsu.sync;
	MGSLPC_INFO *info = dev_to_port(dev);
	unsigned int flags;

	if (debug_level >= DEBUG_LEVEL_INFO)
		printk("%s:hdlcdev_ioctl(%s)\n",__FILE__,dev->name);

	/* return error if TTY interface open */
	if (info->port.count)
		return -EBUSY;

	if (cmd != SIOCWANDEV)
		return hdlc_ioctl(dev, ifr, cmd);

	switch(ifr->ifr_settings.type) {
	case IF_GET_IFACE: /* return current sync_serial_settings */

		ifr->ifr_settings.type = IF_IFACE_SYNC_SERIAL;
		if (ifr->ifr_settings.size < size) {
			ifr->ifr_settings.size = size; /* data size wanted */
			return -ENOBUFS;
		}

		flags = info->params.flags & (HDLC_FLAG_RXC_RXCPIN | HDLC_FLAG_RXC_DPLL |
					      HDLC_FLAG_RXC_BRG    | HDLC_FLAG_RXC_TXCPIN |
					      HDLC_FLAG_TXC_TXCPIN | HDLC_FLAG_TXC_DPLL |
					      HDLC_FLAG_TXC_BRG    | HDLC_FLAG_TXC_RXCPIN);

		switch (flags){
		case (HDLC_FLAG_RXC_RXCPIN | HDLC_FLAG_TXC_TXCPIN): new_line.clock_type = CLOCK_EXT; break;
		case (HDLC_FLAG_RXC_BRG    | HDLC_FLAG_TXC_BRG):    new_line.clock_type = CLOCK_INT; break;
		case (HDLC_FLAG_RXC_RXCPIN | HDLC_FLAG_TXC_BRG):    new_line.clock_type = CLOCK_TXINT; break;
		case (HDLC_FLAG_RXC_RXCPIN | HDLC_FLAG_TXC_RXCPIN): new_line.clock_type = CLOCK_TXFROMRX; break;
		default: new_line.clock_type = CLOCK_DEFAULT;
		}

		new_line.clock_rate = info->params.clock_speed;
		new_line.loopback   = info->params.loopback ? 1:0;

		if (copy_to_user(line, &new_line, size))
			return -EFAULT;
		return 0;

	case IF_IFACE_SYNC_SERIAL: /* set sync_serial_settings */

		if(!capable(CAP_NET_ADMIN))
			return -EPERM;
		if (copy_from_user(&new_line, line, size))
			return -EFAULT;

		switch (new_line.clock_type)
		{
		case CLOCK_EXT:      flags = HDLC_FLAG_RXC_RXCPIN | HDLC_FLAG_TXC_TXCPIN; break;
		case CLOCK_TXFROMRX: flags = HDLC_FLAG_RXC_RXCPIN | HDLC_FLAG_TXC_RXCPIN; break;
		case CLOCK_INT:      flags = HDLC_FLAG_RXC_BRG    | HDLC_FLAG_TXC_BRG;    break;
		case CLOCK_TXINT:    flags = HDLC_FLAG_RXC_RXCPIN | HDLC_FLAG_TXC_BRG;    break;
		case CLOCK_DEFAULT:  flags = info->params.flags &
					     (HDLC_FLAG_RXC_RXCPIN | HDLC_FLAG_RXC_DPLL |
					      HDLC_FLAG_RXC_BRG    | HDLC_FLAG_RXC_TXCPIN |
					      HDLC_FLAG_TXC_TXCPIN | HDLC_FLAG_TXC_DPLL |
					      HDLC_FLAG_TXC_BRG    | HDLC_FLAG_TXC_RXCPIN); break;
		default: return -EINVAL;
		}

		if (new_line.loopback != 0 && new_line.loopback != 1)
			return -EINVAL;

		info->params.flags &= ~(HDLC_FLAG_RXC_RXCPIN | HDLC_FLAG_RXC_DPLL |
					HDLC_FLAG_RXC_BRG    | HDLC_FLAG_RXC_TXCPIN |
					HDLC_FLAG_TXC_TXCPIN | HDLC_FLAG_TXC_DPLL |
					HDLC_FLAG_TXC_BRG    | HDLC_FLAG_TXC_RXCPIN);
		info->params.flags |= flags;

		info->params.loopback = new_line.loopback;

		if (flags & (HDLC_FLAG_RXC_BRG | HDLC_FLAG_TXC_BRG))
			info->params.clock_speed = new_line.clock_rate;
		else
			info->params.clock_speed = 0;

		/* if network interface up, reprogram hardware */
		if (info->netcount) {
			struct tty_struct *tty = tty_port_tty_get(&info->port);
			mgslpc_program_hw(info, tty);
			tty_kref_put(tty);
		}
		return 0;

	default:
		return hdlc_ioctl(dev, ifr, cmd);
	}
}

/**
 * called by network layer when transmit timeout is detected
 *
 * dev  pointer to network device structure
 */
static void hdlcdev_tx_timeout(struct net_device *dev)
{
	MGSLPC_INFO *info = dev_to_port(dev);
	unsigned long flags;

	if (debug_level >= DEBUG_LEVEL_INFO)
		printk("hdlcdev_tx_timeout(%s)\n",dev->name);

	dev->stats.tx_errors++;
	dev->stats.tx_aborted_errors++;

	spin_lock_irqsave(&info->lock,flags);
	tx_stop(info);
	spin_unlock_irqrestore(&info->lock,flags);

	netif_wake_queue(dev);
}

/**
 * called by device driver when transmit completes
 * reenable network layer transmit if stopped
 *
 * info  pointer to device instance information
 */
static void hdlcdev_tx_done(MGSLPC_INFO *info)
{
	if (netif_queue_stopped(info->netdev))
		netif_wake_queue(info->netdev);
}

/**
 * called by device driver when frame received
 * pass frame to network layer
 *
 * info  pointer to device instance information
 * buf   pointer to buffer contianing frame data
 * size  count of data bytes in buf
 */
static void hdlcdev_rx(MGSLPC_INFO *info, char *buf, int size)
{
	struct sk_buff *skb = dev_alloc_skb(size);
	struct net_device *dev = info->netdev;

	if (debug_level >= DEBUG_LEVEL_INFO)
		printk("hdlcdev_rx(%s)\n",dev->name);

	if (skb == NULL) {
		printk(KERN_NOTICE "%s: can't alloc skb, dropping packet\n", dev->name);
		dev->stats.rx_dropped++;
		return;
	}

	memcpy(skb_put(skb, size), buf, size);

	skb->protocol = hdlc_type_trans(skb, dev);

	dev->stats.rx_packets++;
	dev->stats.rx_bytes += size;

	netif_rx(skb);
}

static const struct net_device_ops hdlcdev_ops = {
	.ndo_open       = hdlcdev_open,
	.ndo_stop       = hdlcdev_close,
	.ndo_change_mtu = hdlc_change_mtu,
	.ndo_start_xmit = hdlc_start_xmit,
	.ndo_do_ioctl   = hdlcdev_ioctl,
	.ndo_tx_timeout = hdlcdev_tx_timeout,
};

/**
 * called by device driver when adding device instance
 * do generic HDLC initialization
 *
 * info  pointer to device instance information
 *
 * returns 0 if success, otherwise error code
 */
static int hdlcdev_init(MGSLPC_INFO *info)
{
	int rc;
	struct net_device *dev;
	hdlc_device *hdlc;

	/* allocate and initialize network and HDLC layer objects */

	if (!(dev = alloc_hdlcdev(info))) {
		printk(KERN_ERR "%s:hdlc device allocation failure\n",__FILE__);
		return -ENOMEM;
	}

	/* for network layer reporting purposes only */
	dev->base_addr = info->io_base;
	dev->irq       = info->irq_level;

	/* network layer callbacks and settings */
	dev->netdev_ops	    = &hdlcdev_ops;
	dev->watchdog_timeo = 10 * HZ;
	dev->tx_queue_len   = 50;

	/* generic HDLC layer callbacks and settings */
	hdlc         = dev_to_hdlc(dev);
	hdlc->attach = hdlcdev_attach;
	hdlc->xmit   = hdlcdev_xmit;

	/* register objects with HDLC layer */
	if ((rc = register_hdlc_device(dev))) {
		printk(KERN_WARNING "%s:unable to register hdlc device\n",__FILE__);
		free_netdev(dev);
		return rc;
	}

	info->netdev = dev;
	return 0;
}

/**
 * called by device driver when removing device instance
 * do generic HDLC cleanup
 *
 * info  pointer to device instance information
 */
static void hdlcdev_exit(MGSLPC_INFO *info)
{
	unregister_hdlc_device(info->netdev);
	free_netdev(info->netdev);
	info->netdev = NULL;
}

#endif /* CONFIG_HDLC */