drivers/i2c/busses/scx200_acb.c - kernel/msm-4.19 - Gitiles

 /*  linux/drivers/i2c/scx200_acb.c

     Copyright (c) 2001,2002 Christer Weinigel <wingel@nano-system.com>

     National Semiconductor SCx200 ACCESS.bus support

     Based on i2c-keywest.c which is:
         Copyright (c) 2001 Benjamin Herrenschmidt <benh@kernel.crashing.org>
         Copyright (c) 2000 Philip Edelbrock <phil@stimpy.netroedge.com>

     This program is free software; you can redistribute it and/or
     modify it under the terms of the GNU General Public License as
     published by the Free Software Foundation; either version 2 of the
     License, or (at your option) any later version.

     This program is distributed in the hope that it will be useful,
     but WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     General Public License for more details.

     You should have received a copy of the GNU General Public License
     along with this program; if not, write to the Free Software
     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

 */

 #include <linux/module.h>
 #include <linux/errno.h>
 #include <linux/kernel.h>
 #include <linux/init.h>
 #include <linux/i2c.h>
 #include <linux/smp_lock.h>
 #include <linux/pci.h>
 #include <linux/delay.h>
 #include <asm/io.h>

 #include <linux/scx200.h>

 #define NAME "scx200_acb"

 MODULE_AUTHOR("Christer Weinigel <wingel@nano-system.com>");
 MODULE_DESCRIPTION("NatSemi SCx200 ACCESS.bus Driver");
 MODULE_LICENSE("GPL");

 #define MAX_DEVICES 4
 static int base[MAX_DEVICES] = { 0x820, 0x840 };
 module_param_array(base, int, NULL, 0);
 MODULE_PARM_DESC(base, "Base addresses for the ACCESS.bus controllers");

 #ifdef DEBUG
 #define DBG(x...) printk(KERN_DEBUG NAME ": " x)
 #else
 #define DBG(x...)
 #endif

 /* The hardware supports interrupt driven mode too, but I haven't
    implemented that. */
 #define POLLED_MODE 1
 #define POLL_TIMEOUT (HZ)

 enum scx200_acb_state {
 	state_idle,
 	state_address,
 	state_command,
 	state_repeat_start,
 	state_quick,
 	state_read,
 	state_write,
 };

 static const char *scx200_acb_state_name[] = {
 	"idle",
 	"address",
 	"command",
 	"repeat_start",
 	"quick",
 	"read",
 	"write",
 };

 /* Physical interface */
 struct scx200_acb_iface
 {
 	struct scx200_acb_iface *next;
 	struct i2c_adapter adapter;
 	unsigned base;
 	struct semaphore sem;

 	/* State machine data */
 	enum scx200_acb_state state;
 	int result;
 	u8 address_byte;
 	u8 command;
 	u8 *ptr;
 	char needs_reset;
 	unsigned len;
 };

 /* Register Definitions */
 #define ACBSDA		(iface->base + 0)
 #define ACBST		(iface->base + 1)
 #define    ACBST_SDAST		0x40 /* SDA Status */
 #define    ACBST_BER		0x20
 #define    ACBST_NEGACK		0x10 /* Negative Acknowledge */
 #define    ACBST_STASTR		0x08 /* Stall After Start */
 #define    ACBST_MASTER		0x02
 #define ACBCST		(iface->base + 2)
 #define    ACBCST_BB		0x02
 #define ACBCTL1		(iface->base + 3)
 #define    ACBCTL1_STASTRE	0x80
 #define    ACBCTL1_NMINTE	0x40
 #define	   ACBCTL1_ACK		0x10
 #define	   ACBCTL1_STOP		0x02
 #define	   ACBCTL1_START	0x01
 #define ACBADDR		(iface->base + 4)
 #define ACBCTL2		(iface->base + 5)
 #define    ACBCTL2_ENABLE	0x01

 /************************************************************************/

 static void scx200_acb_machine(struct scx200_acb_iface *iface, u8 status)
 {
 	const char *errmsg;

 	DBG("state %s, status = 0x%02x\n",
 	    scx200_acb_state_name[iface->state], status);

 	if (status & ACBST_BER) {
 		errmsg = "bus error";
 		goto error;
 	}
 	if (!(status & ACBST_MASTER)) {
 		errmsg = "not master";
 		goto error;
 	}
 	if (status & ACBST_NEGACK)
 		goto negack;

 	switch (iface->state) {
 	case state_idle:
 		dev_warn(&iface->adapter.dev, "interrupt in idle state\n");
 		break;

 	case state_address:
 		/* Do a pointer write first */
 		outb(iface->address_byte & ~1, ACBSDA);

 		iface->state = state_command;
 		break;

 	case state_command:
 		outb(iface->command, ACBSDA);

 		if (iface->address_byte & 1)
 			iface->state = state_repeat_start;
 		else
 			iface->state = state_write;
 		break;

 	case state_repeat_start:
 		outb(inb(ACBCTL1) | ACBCTL1_START, ACBCTL1);
 		/* fallthrough */

 	case state_quick:
 		if (iface->address_byte & 1) {
 			if (iface->len == 1)
 				outb(inb(ACBCTL1) | ACBCTL1_ACK, ACBCTL1);
 			else
 				outb(inb(ACBCTL1) & ~ACBCTL1_ACK, ACBCTL1);
 			outb(iface->address_byte, ACBSDA);

 			iface->state = state_read;
 		} else {
 			outb(iface->address_byte, ACBSDA);

 			iface->state = state_write;
 		}
 		break;

 	case state_read:
 		/* Set ACK if receiving the last byte */
 		if (iface->len == 1)
 			outb(inb(ACBCTL1) | ACBCTL1_ACK, ACBCTL1);
 		else
 			outb(inb(ACBCTL1) & ~ACBCTL1_ACK, ACBCTL1);

 		*iface->ptr++ = inb(ACBSDA);
 		--iface->len;

 		if (iface->len == 0) {
 			iface->result = 0;
 			iface->state = state_idle;
 			outb(inb(ACBCTL1) | ACBCTL1_STOP, ACBCTL1);
 		}

 		break;

 	case state_write:
 		if (iface->len == 0) {
 			iface->result = 0;
 			iface->state = state_idle;
 			outb(inb(ACBCTL1) | ACBCTL1_STOP, ACBCTL1);
 			break;
 		}

 		outb(*iface->ptr++, ACBSDA);
 		--iface->len;

 		break;
 	}

 	return;

  negack:
 	DBG("negative acknowledge in state %s\n",
 	    scx200_acb_state_name[iface->state]);

 	iface->state = state_idle;
 	iface->result = -ENXIO;

 	outb(inb(ACBCTL1) | ACBCTL1_STOP, ACBCTL1);
 	outb(ACBST_STASTR | ACBST_NEGACK, ACBST);
 	return;

  error:
 	dev_err(&iface->adapter.dev, "%s in state %s\n", errmsg,
 		scx200_acb_state_name[iface->state]);

 	iface->state = state_idle;
 	iface->result = -EIO;
 	iface->needs_reset = 1;
 }

 static void scx200_acb_timeout(struct scx200_acb_iface *iface)
 {
 	dev_err(&iface->adapter.dev, "timeout in state %s\n",
 		scx200_acb_state_name[iface->state]);

 	iface->state = state_idle;
 	iface->result = -EIO;
 	iface->needs_reset = 1;
 }

 #ifdef POLLED_MODE
 static void scx200_acb_poll(struct scx200_acb_iface *iface)
 {
 	u8 status = 0;
 	unsigned long timeout;

 	timeout = jiffies + POLL_TIMEOUT;
 	while (time_before(jiffies, timeout)) {
 		status = inb(ACBST);
 		if ((status & (ACBST_SDAST|ACBST_BER|ACBST_NEGACK)) != 0) {
 			scx200_acb_machine(iface, status);
 			return;
 		}
 		msleep(10);
 	}

 	scx200_acb_timeout(iface);
 }
 #endif /* POLLED_MODE */

 static void scx200_acb_reset(struct scx200_acb_iface *iface)
 {
 	/* Disable the ACCESS.bus device and Configure the SCL
            frequency: 16 clock cycles */
 	outb(0x70, ACBCTL2);
 	/* Polling mode */
 	outb(0, ACBCTL1);
 	/* Disable slave address */
 	outb(0, ACBADDR);
 	/* Enable the ACCESS.bus device */
 	outb(inb(ACBCTL2) | ACBCTL2_ENABLE, ACBCTL2);
 	/* Free STALL after START */
 	outb(inb(ACBCTL1) & ~(ACBCTL1_STASTRE | ACBCTL1_NMINTE), ACBCTL1);
 	/* Send a STOP */
 	outb(inb(ACBCTL1) | ACBCTL1_STOP, ACBCTL1);
 	/* Clear BER, NEGACK and STASTR bits */
 	outb(ACBST_BER | ACBST_NEGACK | ACBST_STASTR, ACBST);
 	/* Clear BB bit */
 	outb(inb(ACBCST) | ACBCST_BB, ACBCST);
 }

 static s32 scx200_acb_smbus_xfer(struct i2c_adapter *adapter,
 				u16 address, unsigned short flags,
 				char rw, u8 command, int size,
 				union i2c_smbus_data *data)
 {
 	struct scx200_acb_iface *iface = i2c_get_adapdata(adapter);
 	int len;
 	u8 *buffer;
 	u16 cur_word;
 	int rc;

 	switch (size) {
 	case I2C_SMBUS_QUICK:
 	    	len = 0;
 	    	buffer = NULL;
 	    	break;
 	case I2C_SMBUS_BYTE:
 		if (rw == I2C_SMBUS_READ) {
 			len = 1;
 			buffer = &data->byte;
 		} else {
 			len = 1;
 			buffer = &command;
 		}
 	    	break;
 	case I2C_SMBUS_BYTE_DATA:
 	    	len = 1;
 	    	buffer = &data->byte;
 	    	break;
 	case I2C_SMBUS_WORD_DATA:
 		len = 2;
 	    	cur_word = cpu_to_le16(data->word);
 	    	buffer = (u8 *)&cur_word;
 		break;
 	case I2C_SMBUS_BLOCK_DATA:
 	    	len = data->block[0];
 	    	buffer = &data->block[1];
 		break;
 	default:
 	    	return -EINVAL;
 	}

 	DBG("size=%d, address=0x%x, command=0x%x, len=%d, read=%d\n",
 	    size, address, command, len, rw == I2C_SMBUS_READ);

 	if (!len && rw == I2C_SMBUS_READ) {
 		dev_warn(&adapter->dev, "zero length read\n");
 		return -EINVAL;
 	}

 	if (len && !buffer) {
 		dev_warn(&adapter->dev, "nonzero length but no buffer\n");
 		return -EFAULT;
 	}

 	down(&iface->sem);

 	iface->address_byte = address<<1;
 	if (rw == I2C_SMBUS_READ)
 		iface->address_byte |= 1;
 	iface->command = command;
 	iface->ptr = buffer;
 	iface->len = len;
 	iface->result = -EINVAL;
 	iface->needs_reset = 0;

 	outb(inb(ACBCTL1) | ACBCTL1_START, ACBCTL1);

 	if (size == I2C_SMBUS_QUICK || size == I2C_SMBUS_BYTE)
 		iface->state = state_quick;
 	else
 		iface->state = state_address;

 #ifdef POLLED_MODE
 	while (iface->state != state_idle)
 		scx200_acb_poll(iface);
 #else /* POLLED_MODE */
 #error Interrupt driven mode not implemented
 #endif /* POLLED_MODE */

 	if (iface->needs_reset)
 		scx200_acb_reset(iface);

 	rc = iface->result;

 	up(&iface->sem);

 	if (rc == 0 && size == I2C_SMBUS_WORD_DATA && rw == I2C_SMBUS_READ)
 	    	data->word = le16_to_cpu(cur_word);

 #ifdef DEBUG
 	DBG(": transfer done, result: %d", rc);
 	if (buffer) {
 		int i;
 		printk(" data:");
 		for (i = 0; i < len; ++i)
 			printk(" %02x", buffer[i]);
 	}
 	printk("\n");
 #endif

 	return rc;
 }

 static u32 scx200_acb_func(struct i2c_adapter *adapter)
 {
 	return I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE |
 	       I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA |
 	       I2C_FUNC_SMBUS_BLOCK_DATA;
 }

 /* For now, we only handle combined mode (smbus) */
 static struct i2c_algorithm scx200_acb_algorithm = {
 	.smbus_xfer	= scx200_acb_smbus_xfer,
 	.functionality	= scx200_acb_func,
 };

 static struct scx200_acb_iface *scx200_acb_list;

 static int scx200_acb_probe(struct scx200_acb_iface *iface)
 {
 	u8 val;

 	/* Disable the ACCESS.bus device and Configure the SCL
            frequency: 16 clock cycles */
 	outb(0x70, ACBCTL2);

 	if (inb(ACBCTL2) != 0x70) {
 		DBG("ACBCTL2 readback failed\n");
 		return -ENXIO;
 	}

 	outb(inb(ACBCTL1) | ACBCTL1_NMINTE, ACBCTL1);

 	val = inb(ACBCTL1);
 	if (val) {
 		DBG("disabled, but ACBCTL1=0x%02x\n", val);
 		return -ENXIO;
 	}

 	outb(inb(ACBCTL2) | ACBCTL2_ENABLE, ACBCTL2);

 	outb(inb(ACBCTL1) | ACBCTL1_NMINTE, ACBCTL1);

 	val = inb(ACBCTL1);
 	if ((val & ACBCTL1_NMINTE) != ACBCTL1_NMINTE) {
 		DBG("enabled, but NMINTE won't be set, ACBCTL1=0x%02x\n", val);
 		return -ENXIO;
 	}

 	return 0;
 }

 static int  __init scx200_acb_create(int base, int index)
 {
 	struct scx200_acb_iface *iface;
 	struct i2c_adapter *adapter;
 	int rc = 0;
 	char description[64];

 	iface = kmalloc(sizeof(*iface), GFP_KERNEL);
 	if (!iface) {
 		printk(KERN_ERR NAME ": can't allocate memory\n");
 		rc = -ENOMEM;
 		goto errout;
 	}

 	memset(iface, 0, sizeof(*iface));
 	adapter = &iface->adapter;
 	i2c_set_adapdata(adapter, iface);
 	snprintf(adapter->name, I2C_NAME_SIZE, "SCx200 ACB%d", index);
 	adapter->owner = THIS_MODULE;
 	adapter->id = I2C_HW_SMBUS_SCX200;
 	adapter->algo = &scx200_acb_algorithm;
 	adapter->class = I2C_CLASS_HWMON;

 	init_MUTEX(&iface->sem);

 	snprintf(description, sizeof(description), "NatSemi SCx200 ACCESS.bus [%s]", adapter->name);
 	if (request_region(base, 8, description) == 0) {
 		dev_err(&adapter->dev, "can't allocate io 0x%x-0x%x\n",
 			base, base + 8-1);
 		rc = -EBUSY;
 		goto errout;
 	}
 	iface->base = base;

 	rc = scx200_acb_probe(iface);
 	if (rc) {
 		dev_warn(&adapter->dev, "probe failed\n");
 		goto errout;
 	}

 	scx200_acb_reset(iface);

 	if (i2c_add_adapter(adapter) < 0) {
 		dev_err(&adapter->dev, "failed to register\n");
 		rc = -ENODEV;
 		goto errout;
 	}

 	lock_kernel();
 	iface->next = scx200_acb_list;
 	scx200_acb_list = iface;
 	unlock_kernel();

 	return 0;

  errout:
 	if (iface) {
 		if (iface->base)
 			release_region(iface->base, 8);
 		kfree(iface);
 	}
 	return rc;
 }

 static struct pci_device_id scx200[] = {
 	{ PCI_DEVICE(PCI_VENDOR_ID_NS, PCI_DEVICE_ID_NS_SCx200_BRIDGE) },
 	{ PCI_DEVICE(PCI_VENDOR_ID_NS, PCI_DEVICE_ID_NS_SC1100_BRIDGE) },
 	{ },
 };

 static int __init scx200_acb_init(void)
 {
 	int i;
 	int rc;

 	pr_debug(NAME ": NatSemi SCx200 ACCESS.bus Driver\n");

 	/* Verify that this really is a SCx200 processor */
 	if (pci_dev_present(scx200) == 0)
 		return -ENODEV;

 	rc = -ENXIO;
 	for (i = 0; i < MAX_DEVICES; ++i) {
 		if (base[i] > 0)
 			rc = scx200_acb_create(base[i], i);
 	}
 	if (scx200_acb_list)
 		return 0;
 	return rc;
 }

 static void __exit scx200_acb_cleanup(void)
 {
 	struct scx200_acb_iface *iface;
 	lock_kernel();
 	while ((iface = scx200_acb_list) != NULL) {
 		scx200_acb_list = iface->next;
 		unlock_kernel();

 		i2c_del_adapter(&iface->adapter);
 		release_region(iface->base, 8);
 		kfree(iface);
 		lock_kernel();
 	}
 	unlock_kernel();
 }

 module_init(scx200_acb_init);
 module_exit(scx200_acb_cleanup);

 /*
     Local variables:
         compile-command: "make -k -C ../.. SUBDIRS=drivers/i2c modules"
         c-basic-offset: 8
     End:
 */
	/* linux/drivers/i2c/scx200_acb.c

	Copyright (c) 2001,2002 Christer Weinigel <wingel@nano-system.com>

	National Semiconductor SCx200 ACCESS.bus support

	Based on i2c-keywest.c which is:
	Copyright (c) 2001 Benjamin Herrenschmidt <benh@kernel.crashing.org>
	Copyright (c) 2000 Philip Edelbrock <phil@stimpy.netroedge.com>

	This program is free software; you can redistribute it and/or
	modify it under the terms of the GNU General Public License as
	published by the Free Software Foundation; either version 2 of the
	License, or (at your option) any later version.

	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	General Public License for more details.

	You should have received a copy of the GNU General Public License
	along with this program; if not, write to the Free Software
	Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

	*/

	#include <linux/module.h>
	#include <linux/errno.h>
	#include <linux/kernel.h>
	#include <linux/init.h>
	#include <linux/i2c.h>
	#include <linux/smp_lock.h>
	#include <linux/pci.h>
	#include <linux/delay.h>
	#include <asm/io.h>

	#include <linux/scx200.h>

	#define NAME "scx200_acb"

	MODULE_AUTHOR("Christer Weinigel <wingel@nano-system.com>");
	MODULE_DESCRIPTION("NatSemi SCx200 ACCESS.bus Driver");
	MODULE_LICENSE("GPL");

	#define MAX_DEVICES 4
	static int base[MAX_DEVICES] = { 0x820, 0x840 };
	module_param_array(base, int, NULL, 0);
	MODULE_PARM_DESC(base, "Base addresses for the ACCESS.bus controllers");

	#ifdef DEBUG
	#define DBG(x...) printk(KERN_DEBUG NAME ": " x)
	#else
	#define DBG(x...)
	#endif

	/* The hardware supports interrupt driven mode too, but I haven't
	implemented that. */
	#define POLLED_MODE 1
	#define POLL_TIMEOUT (HZ)

	enum scx200_acb_state {
	state_idle,
	state_address,
	state_command,
	state_repeat_start,
	state_quick,
	state_read,
	state_write,
	};

	static const char *scx200_acb_state_name[] = {
	"idle",
	"address",
	"command",
	"repeat_start",
	"quick",
	"read",
	"write",
	};

	/* Physical interface */
	struct scx200_acb_iface
	{
	struct scx200_acb_iface *next;
	struct i2c_adapter adapter;
	unsigned base;
	struct semaphore sem;

	/* State machine data */
	enum scx200_acb_state state;
	int result;
	u8 address_byte;
	u8 command;
	u8 *ptr;
	char needs_reset;
	unsigned len;
	};

	/* Register Definitions */
	#define ACBSDA (iface->base + 0)
	#define ACBST (iface->base + 1)
	#define ACBST_SDAST 0x40 /* SDA Status */
	#define ACBST_BER 0x20
	#define ACBST_NEGACK 0x10 /* Negative Acknowledge */
	#define ACBST_STASTR 0x08 /* Stall After Start */
	#define ACBST_MASTER 0x02
	#define ACBCST (iface->base + 2)
	#define ACBCST_BB 0x02
	#define ACBCTL1 (iface->base + 3)
	#define ACBCTL1_STASTRE 0x80
	#define ACBCTL1_NMINTE 0x40
	#define ACBCTL1_ACK 0x10
	#define ACBCTL1_STOP 0x02
	#define ACBCTL1_START 0x01
	#define ACBADDR (iface->base + 4)
	#define ACBCTL2 (iface->base + 5)
	#define ACBCTL2_ENABLE 0x01

	/************************************************************************/

	static void scx200_acb_machine(struct scx200_acb_iface *iface, u8 status)
	{
	const char *errmsg;

	DBG("state %s, status = 0x%02x\n",
	scx200_acb_state_name[iface->state], status);

	if (status & ACBST_BER) {
	errmsg = "bus error";
	goto error;
	}
	if (!(status & ACBST_MASTER)) {
	errmsg = "not master";
	goto error;
	}
	if (status & ACBST_NEGACK)
	goto negack;

	switch (iface->state) {
	case state_idle:
	dev_warn(&iface->adapter.dev, "interrupt in idle state\n");
	break;

	case state_address:
	/* Do a pointer write first */
	outb(iface->address_byte & ~1, ACBSDA);

	iface->state = state_command;
	break;

	case state_command:
	outb(iface->command, ACBSDA);

	if (iface->address_byte & 1)
	iface->state = state_repeat_start;
	else
	iface->state = state_write;
	break;

	case state_repeat_start:
	outb(inb(ACBCTL1) \| ACBCTL1_START, ACBCTL1);
	/* fallthrough */

	case state_quick:
	if (iface->address_byte & 1) {
	if (iface->len == 1)
	outb(inb(ACBCTL1) \| ACBCTL1_ACK, ACBCTL1);
	else
	outb(inb(ACBCTL1) & ~ACBCTL1_ACK, ACBCTL1);
	outb(iface->address_byte, ACBSDA);

	iface->state = state_read;
	} else {
	outb(iface->address_byte, ACBSDA);

	iface->state = state_write;
	}
	break;

	case state_read:
	/* Set ACK if receiving the last byte */
	if (iface->len == 1)
	outb(inb(ACBCTL1) \| ACBCTL1_ACK, ACBCTL1);
	else
	outb(inb(ACBCTL1) & ~ACBCTL1_ACK, ACBCTL1);

	*iface->ptr++ = inb(ACBSDA);
	--iface->len;

	if (iface->len == 0) {
	iface->result = 0;
	iface->state = state_idle;
	outb(inb(ACBCTL1) \| ACBCTL1_STOP, ACBCTL1);
	}

	break;

	case state_write:
	if (iface->len == 0) {
	iface->result = 0;
	iface->state = state_idle;
	outb(inb(ACBCTL1) \| ACBCTL1_STOP, ACBCTL1);
	break;
	}

	outb(*iface->ptr++, ACBSDA);
	--iface->len;

	break;
	}

	return;

	negack:
	DBG("negative acknowledge in state %s\n",
	scx200_acb_state_name[iface->state]);

	iface->state = state_idle;
	iface->result = -ENXIO;

	outb(inb(ACBCTL1) \| ACBCTL1_STOP, ACBCTL1);
	outb(ACBST_STASTR \| ACBST_NEGACK, ACBST);
	return;

	error:
	dev_err(&iface->adapter.dev, "%s in state %s\n", errmsg,
	scx200_acb_state_name[iface->state]);

	iface->state = state_idle;
	iface->result = -EIO;
	iface->needs_reset = 1;
	}

	static void scx200_acb_timeout(struct scx200_acb_iface *iface)
	{
	dev_err(&iface->adapter.dev, "timeout in state %s\n",
	scx200_acb_state_name[iface->state]);

	iface->state = state_idle;
	iface->result = -EIO;
	iface->needs_reset = 1;
	}

	#ifdef POLLED_MODE
	static void scx200_acb_poll(struct scx200_acb_iface *iface)
	{
	u8 status = 0;
	unsigned long timeout;

	timeout = jiffies + POLL_TIMEOUT;
	while (time_before(jiffies, timeout)) {
	status = inb(ACBST);
	if ((status & (ACBST_SDAST\|ACBST_BER\|ACBST_NEGACK)) != 0) {
	scx200_acb_machine(iface, status);
	return;
	}
	msleep(10);
	}

	scx200_acb_timeout(iface);
	}
	#endif /* POLLED_MODE */

	static void scx200_acb_reset(struct scx200_acb_iface *iface)
	{
	/* Disable the ACCESS.bus device and Configure the SCL
	frequency: 16 clock cycles */
	outb(0x70, ACBCTL2);
	/* Polling mode */
	outb(0, ACBCTL1);
	/* Disable slave address */
	outb(0, ACBADDR);
	/* Enable the ACCESS.bus device */
	outb(inb(ACBCTL2) \| ACBCTL2_ENABLE, ACBCTL2);
	/* Free STALL after START */
	outb(inb(ACBCTL1) & ~(ACBCTL1_STASTRE \| ACBCTL1_NMINTE), ACBCTL1);
	/* Send a STOP */
	outb(inb(ACBCTL1) \| ACBCTL1_STOP, ACBCTL1);
	/* Clear BER, NEGACK and STASTR bits */
	outb(ACBST_BER \| ACBST_NEGACK \| ACBST_STASTR, ACBST);
	/* Clear BB bit */
	outb(inb(ACBCST) \| ACBCST_BB, ACBCST);
	}

	static s32 scx200_acb_smbus_xfer(struct i2c_adapter *adapter,
	u16 address, unsigned short flags,
	char rw, u8 command, int size,
	union i2c_smbus_data *data)
	{
	struct scx200_acb_iface *iface = i2c_get_adapdata(adapter);
	int len;
	u8 *buffer;
	u16 cur_word;
	int rc;

	switch (size) {
	case I2C_SMBUS_QUICK:
	len = 0;
	buffer = NULL;
	break;
	case I2C_SMBUS_BYTE:
	if (rw == I2C_SMBUS_READ) {
	len = 1;
	buffer = &data->byte;
	} else {
	len = 1;
	buffer = &command;
	}
	break;
	case I2C_SMBUS_BYTE_DATA:
	len = 1;
	buffer = &data->byte;
	break;
	case I2C_SMBUS_WORD_DATA:
	len = 2;
	cur_word = cpu_to_le16(data->word);
	buffer = (u8 *)&cur_word;
	break;
	case I2C_SMBUS_BLOCK_DATA:
	len = data->block[0];
	buffer = &data->block[1];
	break;
	default:
	return -EINVAL;
	}

	DBG("size=%d, address=0x%x, command=0x%x, len=%d, read=%d\n",
	size, address, command, len, rw == I2C_SMBUS_READ);

	if (!len && rw == I2C_SMBUS_READ) {
	dev_warn(&adapter->dev, "zero length read\n");
	return -EINVAL;
	}

	if (len && !buffer) {
	dev_warn(&adapter->dev, "nonzero length but no buffer\n");
	return -EFAULT;
	}

	down(&iface->sem);

	iface->address_byte = address<<1;
	if (rw == I2C_SMBUS_READ)
	iface->address_byte \|= 1;
	iface->command = command;
	iface->ptr = buffer;
	iface->len = len;
	iface->result = -EINVAL;
	iface->needs_reset = 0;

	outb(inb(ACBCTL1) \| ACBCTL1_START, ACBCTL1);

	if (size == I2C_SMBUS_QUICK \|\| size == I2C_SMBUS_BYTE)
	iface->state = state_quick;
	else
	iface->state = state_address;

	#ifdef POLLED_MODE
	while (iface->state != state_idle)
	scx200_acb_poll(iface);
	#else /* POLLED_MODE */
	#error Interrupt driven mode not implemented
	#endif /* POLLED_MODE */

	if (iface->needs_reset)
	scx200_acb_reset(iface);

	rc = iface->result;

	up(&iface->sem);

	if (rc == 0 && size == I2C_SMBUS_WORD_DATA && rw == I2C_SMBUS_READ)
	data->word = le16_to_cpu(cur_word);

	#ifdef DEBUG
	DBG(": transfer done, result: %d", rc);
	if (buffer) {
	int i;
	printk(" data:");
	for (i = 0; i < len; ++i)
	printk(" %02x", buffer[i]);
	}
	printk("\n");
	#endif

	return rc;
	}

	static u32 scx200_acb_func(struct i2c_adapter *adapter)
	{
	return I2C_FUNC_SMBUS_QUICK \| I2C_FUNC_SMBUS_BYTE \|
	I2C_FUNC_SMBUS_BYTE_DATA \| I2C_FUNC_SMBUS_WORD_DATA \|
	I2C_FUNC_SMBUS_BLOCK_DATA;
	}

	/* For now, we only handle combined mode (smbus) */
	static struct i2c_algorithm scx200_acb_algorithm = {
	.smbus_xfer = scx200_acb_smbus_xfer,
	.functionality = scx200_acb_func,
	};

	static struct scx200_acb_iface *scx200_acb_list;

	static int scx200_acb_probe(struct scx200_acb_iface *iface)
	{
	u8 val;

	/* Disable the ACCESS.bus device and Configure the SCL
	frequency: 16 clock cycles */
	outb(0x70, ACBCTL2);

	if (inb(ACBCTL2) != 0x70) {
	DBG("ACBCTL2 readback failed\n");
	return -ENXIO;
	}

	outb(inb(ACBCTL1) \| ACBCTL1_NMINTE, ACBCTL1);

	val = inb(ACBCTL1);
	if (val) {
	DBG("disabled, but ACBCTL1=0x%02x\n", val);
	return -ENXIO;
	}

	outb(inb(ACBCTL2) \| ACBCTL2_ENABLE, ACBCTL2);

	outb(inb(ACBCTL1) \| ACBCTL1_NMINTE, ACBCTL1);

	val = inb(ACBCTL1);
	if ((val & ACBCTL1_NMINTE) != ACBCTL1_NMINTE) {
	DBG("enabled, but NMINTE won't be set, ACBCTL1=0x%02x\n", val);
	return -ENXIO;
	}

	return 0;
	}

	static int __init scx200_acb_create(int base, int index)
	{
	struct scx200_acb_iface *iface;
	struct i2c_adapter *adapter;
	int rc = 0;
	char description[64];

	iface = kmalloc(sizeof(*iface), GFP_KERNEL);
	if (!iface) {
	printk(KERN_ERR NAME ": can't allocate memory\n");
	rc = -ENOMEM;
	goto errout;
	}

	memset(iface, 0, sizeof(*iface));
	adapter = &iface->adapter;
	i2c_set_adapdata(adapter, iface);
	snprintf(adapter->name, I2C_NAME_SIZE, "SCx200 ACB%d", index);
	adapter->owner = THIS_MODULE;
	adapter->id = I2C_HW_SMBUS_SCX200;
	adapter->algo = &scx200_acb_algorithm;
	adapter->class = I2C_CLASS_HWMON;

	init_MUTEX(&iface->sem);

	snprintf(description, sizeof(description), "NatSemi SCx200 ACCESS.bus [%s]", adapter->name);
	if (request_region(base, 8, description) == 0) {
	dev_err(&adapter->dev, "can't allocate io 0x%x-0x%x\n",
	base, base + 8-1);
	rc = -EBUSY;
	goto errout;
	}
	iface->base = base;

	rc = scx200_acb_probe(iface);
	if (rc) {
	dev_warn(&adapter->dev, "probe failed\n");
	goto errout;
	}

	scx200_acb_reset(iface);

	if (i2c_add_adapter(adapter) < 0) {
	dev_err(&adapter->dev, "failed to register\n");
	rc = -ENODEV;
	goto errout;
	}

	lock_kernel();
	iface->next = scx200_acb_list;
	scx200_acb_list = iface;
	unlock_kernel();

	return 0;

	errout:
	if (iface) {
	if (iface->base)
	release_region(iface->base, 8);
	kfree(iface);
	}
	return rc;
	}

	static struct pci_device_id scx200[] = {
	{ PCI_DEVICE(PCI_VENDOR_ID_NS, PCI_DEVICE_ID_NS_SCx200_BRIDGE) },
	{ PCI_DEVICE(PCI_VENDOR_ID_NS, PCI_DEVICE_ID_NS_SC1100_BRIDGE) },
	{ },
	};

	static int __init scx200_acb_init(void)
	{
	int i;
	int rc;

	pr_debug(NAME ": NatSemi SCx200 ACCESS.bus Driver\n");

	/* Verify that this really is a SCx200 processor */
	if (pci_dev_present(scx200) == 0)
	return -ENODEV;

	rc = -ENXIO;
	for (i = 0; i < MAX_DEVICES; ++i) {
	if (base[i] > 0)
	rc = scx200_acb_create(base[i], i);
	}
	if (scx200_acb_list)
	return 0;
	return rc;
	}

	static void __exit scx200_acb_cleanup(void)
	{
	struct scx200_acb_iface *iface;
	lock_kernel();
	while ((iface = scx200_acb_list) != NULL) {
	scx200_acb_list = iface->next;
	unlock_kernel();

	i2c_del_adapter(&iface->adapter);
	release_region(iface->base, 8);
	kfree(iface);
	lock_kernel();
	}
	unlock_kernel();
	}

	module_init(scx200_acb_init);
	module_exit(scx200_acb_cleanup);

	/*
	Local variables:
	compile-command: "make -k -C ../.. SUBDIRS=drivers/i2c modules"
	c-basic-offset: 8
	End:
	*/