drivers/tty/serial/altera_uart.c - kernel/msm-4.9 - Gitiles

 /*
  * altera_uart.c -- Altera UART driver
  *
  * Based on mcf.c -- Freescale ColdFire UART driver
  *
  * (C) Copyright 2003-2007, Greg Ungerer <gerg@snapgear.com>
  * (C) Copyright 2008, Thomas Chou <thomas@wytron.com.tw>
  * (C) Copyright 2010, Tobias Klauser <tklauser@distanz.ch>
  *
  * 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.
  */

 #include <linux/kernel.h>
 #include <linux/init.h>
 #include <linux/timer.h>
 #include <linux/interrupt.h>
 #include <linux/module.h>
 #include <linux/console.h>
 #include <linux/tty.h>
 #include <linux/tty_flip.h>
 #include <linux/serial.h>
 #include <linux/serial_core.h>
 #include <linux/platform_device.h>
 #include <linux/of.h>
 #include <linux/io.h>
 #include <linux/altera_uart.h>

 #define DRV_NAME "altera_uart"
 #define SERIAL_ALTERA_MAJOR 204
 #define SERIAL_ALTERA_MINOR 213

 /*
  * Altera UART register definitions according to the Nios UART datasheet:
  * http://www.altera.com/literature/ds/ds_nios_uart.pdf
  */

 #define ALTERA_UART_SIZE		32

 #define ALTERA_UART_RXDATA_REG		0
 #define ALTERA_UART_TXDATA_REG		4
 #define ALTERA_UART_STATUS_REG		8
 #define ALTERA_UART_CONTROL_REG		12
 #define ALTERA_UART_DIVISOR_REG		16
 #define ALTERA_UART_EOP_REG		20

 #define ALTERA_UART_STATUS_PE_MSK	0x0001	/* parity error */
 #define ALTERA_UART_STATUS_FE_MSK	0x0002	/* framing error */
 #define ALTERA_UART_STATUS_BRK_MSK	0x0004	/* break */
 #define ALTERA_UART_STATUS_ROE_MSK	0x0008	/* RX overrun error */
 #define ALTERA_UART_STATUS_TOE_MSK	0x0010	/* TX overrun error */
 #define ALTERA_UART_STATUS_TMT_MSK	0x0020	/* TX shift register state */
 #define ALTERA_UART_STATUS_TRDY_MSK	0x0040	/* TX ready */
 #define ALTERA_UART_STATUS_RRDY_MSK	0x0080	/* RX ready */
 #define ALTERA_UART_STATUS_E_MSK	0x0100	/* exception condition */
 #define ALTERA_UART_STATUS_DCTS_MSK	0x0400	/* CTS logic-level change */
 #define ALTERA_UART_STATUS_CTS_MSK	0x0800	/* CTS logic state */
 #define ALTERA_UART_STATUS_EOP_MSK	0x1000	/* EOP written/read */

 						/* Enable interrupt on... */
 #define ALTERA_UART_CONTROL_PE_MSK	0x0001	/* ...parity error */
 #define ALTERA_UART_CONTROL_FE_MSK	0x0002	/* ...framing error */
 #define ALTERA_UART_CONTROL_BRK_MSK	0x0004	/* ...break */
 #define ALTERA_UART_CONTROL_ROE_MSK	0x0008	/* ...RX overrun */
 #define ALTERA_UART_CONTROL_TOE_MSK	0x0010	/* ...TX overrun */
 #define ALTERA_UART_CONTROL_TMT_MSK	0x0020	/* ...TX shift register empty */
 #define ALTERA_UART_CONTROL_TRDY_MSK	0x0040	/* ...TX ready */
 #define ALTERA_UART_CONTROL_RRDY_MSK	0x0080	/* ...RX ready */
 #define ALTERA_UART_CONTROL_E_MSK	0x0100	/* ...exception*/

 #define ALTERA_UART_CONTROL_TRBK_MSK	0x0200	/* TX break */
 #define ALTERA_UART_CONTROL_DCTS_MSK	0x0400	/* Interrupt on CTS change */
 #define ALTERA_UART_CONTROL_RTS_MSK	0x0800	/* RTS signal */
 #define ALTERA_UART_CONTROL_EOP_MSK	0x1000	/* Interrupt on EOP */

 /*
  * Local per-uart structure.
  */
 struct altera_uart {
 	struct uart_port port;
 	struct timer_list tmr;
 	unsigned int sigs;	/* Local copy of line sigs */
 	unsigned short imr;	/* Local IMR mirror */
 };

 static u32 altera_uart_readl(struct uart_port *port, int reg)
 {
 	return readl(port->membase + (reg << port->regshift));
 }

 static void altera_uart_writel(struct uart_port *port, u32 dat, int reg)
 {
 	writel(dat, port->membase + (reg << port->regshift));
 }

 static unsigned int altera_uart_tx_empty(struct uart_port *port)
 {
 	return (altera_uart_readl(port, ALTERA_UART_STATUS_REG) &
 		ALTERA_UART_STATUS_TMT_MSK) ? TIOCSER_TEMT : 0;
 }

 static unsigned int altera_uart_get_mctrl(struct uart_port *port)
 {
 	struct altera_uart *pp = container_of(port, struct altera_uart, port);
 	unsigned int sigs;

 	sigs = (altera_uart_readl(port, ALTERA_UART_STATUS_REG) &
 	     ALTERA_UART_STATUS_CTS_MSK) ? TIOCM_CTS : 0;
 	sigs |= (pp->sigs & TIOCM_RTS);

 	return sigs;
 }

 static void altera_uart_set_mctrl(struct uart_port *port, unsigned int sigs)
 {
 	struct altera_uart *pp = container_of(port, struct altera_uart, port);

 	pp->sigs = sigs;
 	if (sigs & TIOCM_RTS)
 		pp->imr |= ALTERA_UART_CONTROL_RTS_MSK;
 	else
 		pp->imr &= ~ALTERA_UART_CONTROL_RTS_MSK;
 	altera_uart_writel(port, pp->imr, ALTERA_UART_CONTROL_REG);
 }

 static void altera_uart_start_tx(struct uart_port *port)
 {
 	struct altera_uart *pp = container_of(port, struct altera_uart, port);

 	pp->imr |= ALTERA_UART_CONTROL_TRDY_MSK;
 	altera_uart_writel(port, pp->imr, ALTERA_UART_CONTROL_REG);
 }

 static void altera_uart_stop_tx(struct uart_port *port)
 {
 	struct altera_uart *pp = container_of(port, struct altera_uart, port);

 	pp->imr &= ~ALTERA_UART_CONTROL_TRDY_MSK;
 	altera_uart_writel(port, pp->imr, ALTERA_UART_CONTROL_REG);
 }

 static void altera_uart_stop_rx(struct uart_port *port)
 {
 	struct altera_uart *pp = container_of(port, struct altera_uart, port);

 	pp->imr &= ~ALTERA_UART_CONTROL_RRDY_MSK;
 	altera_uart_writel(port, pp->imr, ALTERA_UART_CONTROL_REG);
 }

 static void altera_uart_break_ctl(struct uart_port *port, int break_state)
 {
 	struct altera_uart *pp = container_of(port, struct altera_uart, port);
 	unsigned long flags;

 	spin_lock_irqsave(&port->lock, flags);
 	if (break_state == -1)
 		pp->imr |= ALTERA_UART_CONTROL_TRBK_MSK;
 	else
 		pp->imr &= ~ALTERA_UART_CONTROL_TRBK_MSK;
 	altera_uart_writel(port, pp->imr, ALTERA_UART_CONTROL_REG);
 	spin_unlock_irqrestore(&port->lock, flags);
 }

 static void altera_uart_set_termios(struct uart_port *port,
 				    struct ktermios *termios,
 				    struct ktermios *old)
 {
 	unsigned long flags;
 	unsigned int baud, baudclk;

 	baud = uart_get_baud_rate(port, termios, old, 0, 4000000);
 	baudclk = port->uartclk / baud;

 	if (old)
 		tty_termios_copy_hw(termios, old);
 	tty_termios_encode_baud_rate(termios, baud, baud);

 	spin_lock_irqsave(&port->lock, flags);
 	uart_update_timeout(port, termios->c_cflag, baud);
 	altera_uart_writel(port, baudclk, ALTERA_UART_DIVISOR_REG);
 	spin_unlock_irqrestore(&port->lock, flags);

 	/*
 	 * FIXME: port->read_status_mask and port->ignore_status_mask
 	 * need to be initialized based on termios settings for
 	 * INPCK, IGNBRK, IGNPAR, PARMRK, BRKINT
 	 */
 }

 static void altera_uart_rx_chars(struct altera_uart *pp)
 {
 	struct uart_port *port = &pp->port;
 	unsigned char ch, flag;
 	unsigned short status;

 	while ((status = altera_uart_readl(port, ALTERA_UART_STATUS_REG)) &
 	       ALTERA_UART_STATUS_RRDY_MSK) {
 		ch = altera_uart_readl(port, ALTERA_UART_RXDATA_REG);
 		flag = TTY_NORMAL;
 		port->icount.rx++;

 		if (status & ALTERA_UART_STATUS_E_MSK) {
 			altera_uart_writel(port, status,
 					   ALTERA_UART_STATUS_REG);

 			if (status & ALTERA_UART_STATUS_BRK_MSK) {
 				port->icount.brk++;
 				if (uart_handle_break(port))
 					continue;
 			} else if (status & ALTERA_UART_STATUS_PE_MSK) {
 				port->icount.parity++;
 			} else if (status & ALTERA_UART_STATUS_ROE_MSK) {
 				port->icount.overrun++;
 			} else if (status & ALTERA_UART_STATUS_FE_MSK) {
 				port->icount.frame++;
 			}

 			status &= port->read_status_mask;

 			if (status & ALTERA_UART_STATUS_BRK_MSK)
 				flag = TTY_BREAK;
 			else if (status & ALTERA_UART_STATUS_PE_MSK)
 				flag = TTY_PARITY;
 			else if (status & ALTERA_UART_STATUS_FE_MSK)
 				flag = TTY_FRAME;
 		}

 		if (uart_handle_sysrq_char(port, ch))
 			continue;
 		uart_insert_char(port, status, ALTERA_UART_STATUS_ROE_MSK, ch,
 				 flag);
 	}

 	spin_unlock(&port->lock);
 	tty_flip_buffer_push(&port->state->port);
 	spin_lock(&port->lock);
 }

 static void altera_uart_tx_chars(struct altera_uart *pp)
 {
 	struct uart_port *port = &pp->port;
 	struct circ_buf *xmit = &port->state->xmit;

 	if (port->x_char) {
 		/* Send special char - probably flow control */
 		altera_uart_writel(port, port->x_char, ALTERA_UART_TXDATA_REG);
 		port->x_char = 0;
 		port->icount.tx++;
 		return;
 	}

 	while (altera_uart_readl(port, ALTERA_UART_STATUS_REG) &
 	       ALTERA_UART_STATUS_TRDY_MSK) {
 		if (xmit->head == xmit->tail)
 			break;
 		altera_uart_writel(port, xmit->buf[xmit->tail],
 		       ALTERA_UART_TXDATA_REG);
 		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
 		port->icount.tx++;
 	}

 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 		uart_write_wakeup(port);

 	if (xmit->head == xmit->tail) {
 		pp->imr &= ~ALTERA_UART_CONTROL_TRDY_MSK;
 		altera_uart_writel(port, pp->imr, ALTERA_UART_CONTROL_REG);
 	}
 }

 static irqreturn_t altera_uart_interrupt(int irq, void *data)
 {
 	struct uart_port *port = data;
 	struct altera_uart *pp = container_of(port, struct altera_uart, port);
 	unsigned int isr;

 	isr = altera_uart_readl(port, ALTERA_UART_STATUS_REG) & pp->imr;

 	spin_lock(&port->lock);
 	if (isr & ALTERA_UART_STATUS_RRDY_MSK)
 		altera_uart_rx_chars(pp);
 	if (isr & ALTERA_UART_STATUS_TRDY_MSK)
 		altera_uart_tx_chars(pp);
 	spin_unlock(&port->lock);

 	return IRQ_RETVAL(isr);
 }

 static void altera_uart_timer(unsigned long data)
 {
 	struct uart_port *port = (void *)data;
 	struct altera_uart *pp = container_of(port, struct altera_uart, port);

 	altera_uart_interrupt(0, port);
 	mod_timer(&pp->tmr, jiffies + uart_poll_timeout(port));
 }

 static void altera_uart_config_port(struct uart_port *port, int flags)
 {
 	port->type = PORT_ALTERA_UART;

 	/* Clear mask, so no surprise interrupts. */
 	altera_uart_writel(port, 0, ALTERA_UART_CONTROL_REG);
 	/* Clear status register */
 	altera_uart_writel(port, 0, ALTERA_UART_STATUS_REG);
 }

 static int altera_uart_startup(struct uart_port *port)
 {
 	struct altera_uart *pp = container_of(port, struct altera_uart, port);
 	unsigned long flags;
 	int ret;

 	if (!port->irq) {
 		setup_timer(&pp->tmr, altera_uart_timer, (unsigned long)port);
 		mod_timer(&pp->tmr, jiffies + uart_poll_timeout(port));
 		return 0;
 	}

 	ret = request_irq(port->irq, altera_uart_interrupt, 0,
 			DRV_NAME, port);
 	if (ret) {
 		pr_err(DRV_NAME ": unable to attach Altera UART %d "
 		       "interrupt vector=%d\n", port->line, port->irq);
 		return ret;
 	}

 	spin_lock_irqsave(&port->lock, flags);

 	/* Enable RX interrupts now */
 	pp->imr = ALTERA_UART_CONTROL_RRDY_MSK;
 	writel(pp->imr, port->membase + ALTERA_UART_CONTROL_REG);

 	spin_unlock_irqrestore(&port->lock, flags);

 	return 0;
 }

 static void altera_uart_shutdown(struct uart_port *port)
 {
 	struct altera_uart *pp = container_of(port, struct altera_uart, port);
 	unsigned long flags;

 	spin_lock_irqsave(&port->lock, flags);

 	/* Disable all interrupts now */
 	pp->imr = 0;
 	writel(pp->imr, port->membase + ALTERA_UART_CONTROL_REG);

 	spin_unlock_irqrestore(&port->lock, flags);

 	if (port->irq)
 		free_irq(port->irq, port);
 	else
 		del_timer_sync(&pp->tmr);
 }

 static const char *altera_uart_type(struct uart_port *port)
 {
 	return (port->type == PORT_ALTERA_UART) ? "Altera UART" : NULL;
 }

 static int altera_uart_request_port(struct uart_port *port)
 {
 	/* UARTs always present */
 	return 0;
 }

 static void altera_uart_release_port(struct uart_port *port)
 {
 	/* Nothing to release... */
 }

 static int altera_uart_verify_port(struct uart_port *port,
 				   struct serial_struct *ser)
 {
 	if ((ser->type != PORT_UNKNOWN) && (ser->type != PORT_ALTERA_UART))
 		return -EINVAL;
 	return 0;
 }

 #ifdef CONFIG_CONSOLE_POLL
 static int altera_uart_poll_get_char(struct uart_port *port)
 {
 	while (!(altera_uart_readl(port, ALTERA_UART_STATUS_REG) &
 		 ALTERA_UART_STATUS_RRDY_MSK))
 		cpu_relax();

 	return altera_uart_readl(port, ALTERA_UART_RXDATA_REG);
 }

 static void altera_uart_poll_put_char(struct uart_port *port, unsigned char c)
 {
 	while (!(altera_uart_readl(port, ALTERA_UART_STATUS_REG) &
 		 ALTERA_UART_STATUS_TRDY_MSK))
 		cpu_relax();

 	altera_uart_writel(port, c, ALTERA_UART_TXDATA_REG);
 }
 #endif

 /*
  *	Define the basic serial functions we support.
  */
 static struct uart_ops altera_uart_ops = {
 	.tx_empty	= altera_uart_tx_empty,
 	.get_mctrl	= altera_uart_get_mctrl,
 	.set_mctrl	= altera_uart_set_mctrl,
 	.start_tx	= altera_uart_start_tx,
 	.stop_tx	= altera_uart_stop_tx,
 	.stop_rx	= altera_uart_stop_rx,
 	.break_ctl	= altera_uart_break_ctl,
 	.startup	= altera_uart_startup,
 	.shutdown	= altera_uart_shutdown,
 	.set_termios	= altera_uart_set_termios,
 	.type		= altera_uart_type,
 	.request_port	= altera_uart_request_port,
 	.release_port	= altera_uart_release_port,
 	.config_port	= altera_uart_config_port,
 	.verify_port	= altera_uart_verify_port,
 #ifdef CONFIG_CONSOLE_POLL
 	.poll_get_char	= altera_uart_poll_get_char,
 	.poll_put_char	= altera_uart_poll_put_char,
 #endif
 };

 static struct altera_uart altera_uart_ports[CONFIG_SERIAL_ALTERA_UART_MAXPORTS];

 #if defined(CONFIG_SERIAL_ALTERA_UART_CONSOLE)

 static void altera_uart_console_putc(struct uart_port *port, int c)
 {
 	while (!(altera_uart_readl(port, ALTERA_UART_STATUS_REG) &
 		 ALTERA_UART_STATUS_TRDY_MSK))
 		cpu_relax();

 	writel(c, port->membase + ALTERA_UART_TXDATA_REG);
 }

 static void altera_uart_console_write(struct console *co, const char *s,
 				      unsigned int count)
 {
 	struct uart_port *port = &(altera_uart_ports + co->index)->port;

 	uart_console_write(port, s, count, altera_uart_console_putc);
 }

 static int __init altera_uart_console_setup(struct console *co, char *options)
 {
 	struct uart_port *port;
 	int baud = CONFIG_SERIAL_ALTERA_UART_BAUDRATE;
 	int bits = 8;
 	int parity = 'n';
 	int flow = 'n';

 	if (co->index < 0 || co->index >= CONFIG_SERIAL_ALTERA_UART_MAXPORTS)
 		return -EINVAL;
 	port = &altera_uart_ports[co->index].port;
 	if (!port->membase)
 		return -ENODEV;

 	if (options)
 		uart_parse_options(options, &baud, &parity, &bits, &flow);

 	return uart_set_options(port, co, baud, parity, bits, flow);
 }

 static struct uart_driver altera_uart_driver;

 static struct console altera_uart_console = {
 	.name	= "ttyAL",
 	.write	= altera_uart_console_write,
 	.device	= uart_console_device,
 	.setup	= altera_uart_console_setup,
 	.flags	= CON_PRINTBUFFER,
 	.index	= -1,
 	.data	= &altera_uart_driver,
 };

 static int __init altera_uart_console_init(void)
 {
 	register_console(&altera_uart_console);
 	return 0;
 }

 console_initcall(altera_uart_console_init);

 #define	ALTERA_UART_CONSOLE	(&altera_uart_console)

 #else

 #define	ALTERA_UART_CONSOLE	NULL

 #endif /* CONFIG_ALTERA_UART_CONSOLE */

 /*
  *	Define the altera_uart UART driver structure.
  */
 static struct uart_driver altera_uart_driver = {
 	.owner		= THIS_MODULE,
 	.driver_name	= DRV_NAME,
 	.dev_name	= "ttyAL",
 	.major		= SERIAL_ALTERA_MAJOR,
 	.minor		= SERIAL_ALTERA_MINOR,
 	.nr		= CONFIG_SERIAL_ALTERA_UART_MAXPORTS,
 	.cons		= ALTERA_UART_CONSOLE,
 };

 #ifdef CONFIG_OF
 static int altera_uart_get_of_uartclk(struct platform_device *pdev,
 				      struct uart_port *port)
 {
 	int len;
 	const __be32 *clk;

 	clk = of_get_property(pdev->dev.of_node, "clock-frequency", &len);
 	if (!clk || len < sizeof(__be32))
 		return -ENODEV;

 	port->uartclk = be32_to_cpup(clk);

 	return 0;
 }
 #else
 static int altera_uart_get_of_uartclk(struct platform_device *pdev,
 				      struct uart_port *port)
 {
 	return -ENODEV;
 }
 #endif /* CONFIG_OF */

 static int altera_uart_probe(struct platform_device *pdev)
 {
 	struct altera_uart_platform_uart *platp = dev_get_platdata(&pdev->dev);
 	struct uart_port *port;
 	struct resource *res_mem;
 	struct resource *res_irq;
 	int i = pdev->id;
 	int ret;

 	/* if id is -1 scan for a free id and use that one */
 	if (i == -1) {
 		for (i = 0; i < CONFIG_SERIAL_ALTERA_UART_MAXPORTS; i++)
 			if (altera_uart_ports[i].port.mapbase == 0)
 				break;
 	}

 	if (i < 0 || i >= CONFIG_SERIAL_ALTERA_UART_MAXPORTS)
 		return -EINVAL;

 	port = &altera_uart_ports[i].port;

 	res_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	if (res_mem)
 		port->mapbase = res_mem->start;
 	else if (platp)
 		port->mapbase = platp->mapbase;
 	else
 		return -EINVAL;

 	res_irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
 	if (res_irq)
 		port->irq = res_irq->start;
 	else if (platp)
 		port->irq = platp->irq;

 	/* Check platform data first so we can override device node data */
 	if (platp)
 		port->uartclk = platp->uartclk;
 	else {
 		ret = altera_uart_get_of_uartclk(pdev, port);
 		if (ret)
 			return ret;
 	}

 	port->membase = ioremap(port->mapbase, ALTERA_UART_SIZE);
 	if (!port->membase)
 		return -ENOMEM;

 	if (platp)
 		port->regshift = platp->bus_shift;
 	else
 		port->regshift = 0;

 	port->line = i;
 	port->type = PORT_ALTERA_UART;
 	port->iotype = SERIAL_IO_MEM;
 	port->ops = &altera_uart_ops;
 	port->flags = UPF_BOOT_AUTOCONF;

 	platform_set_drvdata(pdev, port);

 	uart_add_one_port(&altera_uart_driver, port);

 	return 0;
 }

 static int altera_uart_remove(struct platform_device *pdev)
 {
 	struct uart_port *port = platform_get_drvdata(pdev);

 	if (port) {
 		uart_remove_one_port(&altera_uart_driver, port);
 		port->mapbase = 0;
 	}

 	return 0;
 }

 #ifdef CONFIG_OF
 static const struct of_device_id altera_uart_match[] = {
 	{ .compatible = "ALTR,uart-1.0", },
 	{ .compatible = "altr,uart-1.0", },
 	{},
 };
 MODULE_DEVICE_TABLE(of, altera_uart_match);
 #endif /* CONFIG_OF */

 static struct platform_driver altera_uart_platform_driver = {
 	.probe	= altera_uart_probe,
 	.remove	= altera_uart_remove,
 	.driver	= {
 		.name		= DRV_NAME,
 		.of_match_table	= of_match_ptr(altera_uart_match),
 	},
 };

 static int __init altera_uart_init(void)
 {
 	int rc;

 	rc = uart_register_driver(&altera_uart_driver);
 	if (rc)
 		return rc;
 	rc = platform_driver_register(&altera_uart_platform_driver);
 	if (rc)
 		uart_unregister_driver(&altera_uart_driver);
 	return rc;
 }

 static void __exit altera_uart_exit(void)
 {
 	platform_driver_unregister(&altera_uart_platform_driver);
 	uart_unregister_driver(&altera_uart_driver);
 }

 module_init(altera_uart_init);
 module_exit(altera_uart_exit);

 MODULE_DESCRIPTION("Altera UART driver");
 MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>");
 MODULE_LICENSE("GPL");
 MODULE_ALIAS("platform:" DRV_NAME);
 MODULE_ALIAS_CHARDEV_MAJOR(SERIAL_ALTERA_MAJOR);
	/*
	* altera_uart.c -- Altera UART driver
	*
	* Based on mcf.c -- Freescale ColdFire UART driver
	*
	* (C) Copyright 2003-2007, Greg Ungerer <gerg@snapgear.com>
	* (C) Copyright 2008, Thomas Chou <thomas@wytron.com.tw>
	* (C) Copyright 2010, Tobias Klauser <tklauser@distanz.ch>
	*
	* 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.
	*/

	#include <linux/kernel.h>
	#include <linux/init.h>
	#include <linux/timer.h>
	#include <linux/interrupt.h>
	#include <linux/module.h>
	#include <linux/console.h>
	#include <linux/tty.h>
	#include <linux/tty_flip.h>
	#include <linux/serial.h>
	#include <linux/serial_core.h>
	#include <linux/platform_device.h>
	#include <linux/of.h>
	#include <linux/io.h>
	#include <linux/altera_uart.h>

	#define DRV_NAME "altera_uart"
	#define SERIAL_ALTERA_MAJOR 204
	#define SERIAL_ALTERA_MINOR 213

	/*
	* Altera UART register definitions according to the Nios UART datasheet:
	* http://www.altera.com/literature/ds/ds_nios_uart.pdf
	*/

	#define ALTERA_UART_SIZE 32

	#define ALTERA_UART_RXDATA_REG 0
	#define ALTERA_UART_TXDATA_REG 4
	#define ALTERA_UART_STATUS_REG 8
	#define ALTERA_UART_CONTROL_REG 12
	#define ALTERA_UART_DIVISOR_REG 16
	#define ALTERA_UART_EOP_REG 20

	#define ALTERA_UART_STATUS_PE_MSK 0x0001 /* parity error */
	#define ALTERA_UART_STATUS_FE_MSK 0x0002 /* framing error */
	#define ALTERA_UART_STATUS_BRK_MSK 0x0004 /* break */
	#define ALTERA_UART_STATUS_ROE_MSK 0x0008 /* RX overrun error */
	#define ALTERA_UART_STATUS_TOE_MSK 0x0010 /* TX overrun error */
	#define ALTERA_UART_STATUS_TMT_MSK 0x0020 /* TX shift register state */
	#define ALTERA_UART_STATUS_TRDY_MSK 0x0040 /* TX ready */
	#define ALTERA_UART_STATUS_RRDY_MSK 0x0080 /* RX ready */
	#define ALTERA_UART_STATUS_E_MSK 0x0100 /* exception condition */
	#define ALTERA_UART_STATUS_DCTS_MSK 0x0400 /* CTS logic-level change */
	#define ALTERA_UART_STATUS_CTS_MSK 0x0800 /* CTS logic state */
	#define ALTERA_UART_STATUS_EOP_MSK 0x1000 /* EOP written/read */

	/* Enable interrupt on... */
	#define ALTERA_UART_CONTROL_PE_MSK 0x0001 /* ...parity error */
	#define ALTERA_UART_CONTROL_FE_MSK 0x0002 /* ...framing error */
	#define ALTERA_UART_CONTROL_BRK_MSK 0x0004 /* ...break */
	#define ALTERA_UART_CONTROL_ROE_MSK 0x0008 /* ...RX overrun */
	#define ALTERA_UART_CONTROL_TOE_MSK 0x0010 /* ...TX overrun */
	#define ALTERA_UART_CONTROL_TMT_MSK 0x0020 /* ...TX shift register empty */
	#define ALTERA_UART_CONTROL_TRDY_MSK 0x0040 /* ...TX ready */
	#define ALTERA_UART_CONTROL_RRDY_MSK 0x0080 /* ...RX ready */
	#define ALTERA_UART_CONTROL_E_MSK 0x0100 /* ...exception*/

	#define ALTERA_UART_CONTROL_TRBK_MSK 0x0200 /* TX break */
	#define ALTERA_UART_CONTROL_DCTS_MSK 0x0400 /* Interrupt on CTS change */
	#define ALTERA_UART_CONTROL_RTS_MSK 0x0800 /* RTS signal */
	#define ALTERA_UART_CONTROL_EOP_MSK 0x1000 /* Interrupt on EOP */

	/*
	* Local per-uart structure.
	*/
	struct altera_uart {
	struct uart_port port;
	struct timer_list tmr;
	unsigned int sigs; /* Local copy of line sigs */
	unsigned short imr; /* Local IMR mirror */
	};

	static u32 altera_uart_readl(struct uart_port *port, int reg)
	{
	return readl(port->membase + (reg << port->regshift));
	}

	static void altera_uart_writel(struct uart_port *port, u32 dat, int reg)
	{
	writel(dat, port->membase + (reg << port->regshift));
	}

	static unsigned int altera_uart_tx_empty(struct uart_port *port)
	{
	return (altera_uart_readl(port, ALTERA_UART_STATUS_REG) &
	ALTERA_UART_STATUS_TMT_MSK) ? TIOCSER_TEMT : 0;
	}

	static unsigned int altera_uart_get_mctrl(struct uart_port *port)
	{
	struct altera_uart *pp = container_of(port, struct altera_uart, port);
	unsigned int sigs;

	sigs = (altera_uart_readl(port, ALTERA_UART_STATUS_REG) &
	ALTERA_UART_STATUS_CTS_MSK) ? TIOCM_CTS : 0;
	sigs \|= (pp->sigs & TIOCM_RTS);

	return sigs;
	}

	static void altera_uart_set_mctrl(struct uart_port *port, unsigned int sigs)
	{
	struct altera_uart *pp = container_of(port, struct altera_uart, port);

	pp->sigs = sigs;
	if (sigs & TIOCM_RTS)
	pp->imr \|= ALTERA_UART_CONTROL_RTS_MSK;
	else
	pp->imr &= ~ALTERA_UART_CONTROL_RTS_MSK;
	altera_uart_writel(port, pp->imr, ALTERA_UART_CONTROL_REG);
	}

	static void altera_uart_start_tx(struct uart_port *port)
	{
	struct altera_uart *pp = container_of(port, struct altera_uart, port);

	pp->imr \|= ALTERA_UART_CONTROL_TRDY_MSK;
	altera_uart_writel(port, pp->imr, ALTERA_UART_CONTROL_REG);
	}

	static void altera_uart_stop_tx(struct uart_port *port)
	{
	struct altera_uart *pp = container_of(port, struct altera_uart, port);

	pp->imr &= ~ALTERA_UART_CONTROL_TRDY_MSK;
	altera_uart_writel(port, pp->imr, ALTERA_UART_CONTROL_REG);
	}

	static void altera_uart_stop_rx(struct uart_port *port)
	{
	struct altera_uart *pp = container_of(port, struct altera_uart, port);

	pp->imr &= ~ALTERA_UART_CONTROL_RRDY_MSK;
	altera_uart_writel(port, pp->imr, ALTERA_UART_CONTROL_REG);
	}

	static void altera_uart_break_ctl(struct uart_port *port, int break_state)
	{
	struct altera_uart *pp = container_of(port, struct altera_uart, port);
	unsigned long flags;

	spin_lock_irqsave(&port->lock, flags);
	if (break_state == -1)
	pp->imr \|= ALTERA_UART_CONTROL_TRBK_MSK;
	else
	pp->imr &= ~ALTERA_UART_CONTROL_TRBK_MSK;
	altera_uart_writel(port, pp->imr, ALTERA_UART_CONTROL_REG);
	spin_unlock_irqrestore(&port->lock, flags);
	}

	static void altera_uart_set_termios(struct uart_port *port,
	struct ktermios *termios,
	struct ktermios *old)
	{
	unsigned long flags;
	unsigned int baud, baudclk;

	baud = uart_get_baud_rate(port, termios, old, 0, 4000000);
	baudclk = port->uartclk / baud;

	if (old)
	tty_termios_copy_hw(termios, old);
	tty_termios_encode_baud_rate(termios, baud, baud);

	spin_lock_irqsave(&port->lock, flags);
	uart_update_timeout(port, termios->c_cflag, baud);
	altera_uart_writel(port, baudclk, ALTERA_UART_DIVISOR_REG);
	spin_unlock_irqrestore(&port->lock, flags);

	/*
	* FIXME: port->read_status_mask and port->ignore_status_mask
	* need to be initialized based on termios settings for
	* INPCK, IGNBRK, IGNPAR, PARMRK, BRKINT
	*/
	}

	static void altera_uart_rx_chars(struct altera_uart *pp)
	{
	struct uart_port *port = &pp->port;
	unsigned char ch, flag;
	unsigned short status;

	while ((status = altera_uart_readl(port, ALTERA_UART_STATUS_REG)) &
	ALTERA_UART_STATUS_RRDY_MSK) {
	ch = altera_uart_readl(port, ALTERA_UART_RXDATA_REG);
	flag = TTY_NORMAL;
	port->icount.rx++;

	if (status & ALTERA_UART_STATUS_E_MSK) {
	altera_uart_writel(port, status,
	ALTERA_UART_STATUS_REG);

	if (status & ALTERA_UART_STATUS_BRK_MSK) {
	port->icount.brk++;
	if (uart_handle_break(port))
	continue;
	} else if (status & ALTERA_UART_STATUS_PE_MSK) {
	port->icount.parity++;
	} else if (status & ALTERA_UART_STATUS_ROE_MSK) {
	port->icount.overrun++;
	} else if (status & ALTERA_UART_STATUS_FE_MSK) {
	port->icount.frame++;
	}

	status &= port->read_status_mask;

	if (status & ALTERA_UART_STATUS_BRK_MSK)
	flag = TTY_BREAK;
	else if (status & ALTERA_UART_STATUS_PE_MSK)
	flag = TTY_PARITY;
	else if (status & ALTERA_UART_STATUS_FE_MSK)
	flag = TTY_FRAME;
	}

	if (uart_handle_sysrq_char(port, ch))
	continue;
	uart_insert_char(port, status, ALTERA_UART_STATUS_ROE_MSK, ch,
	flag);
	}

	spin_unlock(&port->lock);
	tty_flip_buffer_push(&port->state->port);
	spin_lock(&port->lock);
	}

	static void altera_uart_tx_chars(struct altera_uart *pp)
	{
	struct uart_port *port = &pp->port;
	struct circ_buf *xmit = &port->state->xmit;

	if (port->x_char) {
	/* Send special char - probably flow control */
	altera_uart_writel(port, port->x_char, ALTERA_UART_TXDATA_REG);
	port->x_char = 0;
	port->icount.tx++;
	return;
	}

	while (altera_uart_readl(port, ALTERA_UART_STATUS_REG) &
	ALTERA_UART_STATUS_TRDY_MSK) {
	if (xmit->head == xmit->tail)
	break;
	altera_uart_writel(port, xmit->buf[xmit->tail],
	ALTERA_UART_TXDATA_REG);
	xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
	port->icount.tx++;
	}

	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
	uart_write_wakeup(port);

	if (xmit->head == xmit->tail) {
	pp->imr &= ~ALTERA_UART_CONTROL_TRDY_MSK;
	altera_uart_writel(port, pp->imr, ALTERA_UART_CONTROL_REG);
	}
	}

	static irqreturn_t altera_uart_interrupt(int irq, void *data)
	{
	struct uart_port *port = data;
	struct altera_uart *pp = container_of(port, struct altera_uart, port);
	unsigned int isr;

	isr = altera_uart_readl(port, ALTERA_UART_STATUS_REG) & pp->imr;

	spin_lock(&port->lock);
	if (isr & ALTERA_UART_STATUS_RRDY_MSK)
	altera_uart_rx_chars(pp);
	if (isr & ALTERA_UART_STATUS_TRDY_MSK)
	altera_uart_tx_chars(pp);
	spin_unlock(&port->lock);

	return IRQ_RETVAL(isr);
	}

	static void altera_uart_timer(unsigned long data)
	{
	struct uart_port port = (void )data;
	struct altera_uart *pp = container_of(port, struct altera_uart, port);

	altera_uart_interrupt(0, port);
	mod_timer(&pp->tmr, jiffies + uart_poll_timeout(port));
	}

	static void altera_uart_config_port(struct uart_port *port, int flags)
	{
	port->type = PORT_ALTERA_UART;

	/* Clear mask, so no surprise interrupts. */
	altera_uart_writel(port, 0, ALTERA_UART_CONTROL_REG);
	/* Clear status register */
	altera_uart_writel(port, 0, ALTERA_UART_STATUS_REG);
	}

	static int altera_uart_startup(struct uart_port *port)
	{
	struct altera_uart *pp = container_of(port, struct altera_uart, port);
	unsigned long flags;
	int ret;

	if (!port->irq) {
	setup_timer(&pp->tmr, altera_uart_timer, (unsigned long)port);
	mod_timer(&pp->tmr, jiffies + uart_poll_timeout(port));
	return 0;
	}

	ret = request_irq(port->irq, altera_uart_interrupt, 0,
	DRV_NAME, port);
	if (ret) {
	pr_err(DRV_NAME ": unable to attach Altera UART %d "
	"interrupt vector=%d\n", port->line, port->irq);
	return ret;
	}

	spin_lock_irqsave(&port->lock, flags);

	/* Enable RX interrupts now */
	pp->imr = ALTERA_UART_CONTROL_RRDY_MSK;
	writel(pp->imr, port->membase + ALTERA_UART_CONTROL_REG);

	spin_unlock_irqrestore(&port->lock, flags);

	return 0;
	}

	static void altera_uart_shutdown(struct uart_port *port)
	{
	struct altera_uart *pp = container_of(port, struct altera_uart, port);
	unsigned long flags;

	spin_lock_irqsave(&port->lock, flags);

	/* Disable all interrupts now */
	pp->imr = 0;
	writel(pp->imr, port->membase + ALTERA_UART_CONTROL_REG);

	spin_unlock_irqrestore(&port->lock, flags);

	if (port->irq)
	free_irq(port->irq, port);
	else
	del_timer_sync(&pp->tmr);
	}

	static const char altera_uart_type(struct uart_port port)
	{
	return (port->type == PORT_ALTERA_UART) ? "Altera UART" : NULL;
	}

	static int altera_uart_request_port(struct uart_port *port)
	{
	/* UARTs always present */
	return 0;
	}

	static void altera_uart_release_port(struct uart_port *port)
	{
	/* Nothing to release... */
	}

	static int altera_uart_verify_port(struct uart_port *port,
	struct serial_struct *ser)
	{
	if ((ser->type != PORT_UNKNOWN) && (ser->type != PORT_ALTERA_UART))
	return -EINVAL;
	return 0;
	}

	#ifdef CONFIG_CONSOLE_POLL
	static int altera_uart_poll_get_char(struct uart_port *port)
	{
	while (!(altera_uart_readl(port, ALTERA_UART_STATUS_REG) &
	ALTERA_UART_STATUS_RRDY_MSK))
	cpu_relax();

	return altera_uart_readl(port, ALTERA_UART_RXDATA_REG);
	}

	static void altera_uart_poll_put_char(struct uart_port *port, unsigned char c)
	{
	while (!(altera_uart_readl(port, ALTERA_UART_STATUS_REG) &
	ALTERA_UART_STATUS_TRDY_MSK))
	cpu_relax();

	altera_uart_writel(port, c, ALTERA_UART_TXDATA_REG);
	}
	#endif

	/*
	* Define the basic serial functions we support.
	*/
	static struct uart_ops altera_uart_ops = {
	.tx_empty = altera_uart_tx_empty,
	.get_mctrl = altera_uart_get_mctrl,
	.set_mctrl = altera_uart_set_mctrl,
	.start_tx = altera_uart_start_tx,
	.stop_tx = altera_uart_stop_tx,
	.stop_rx = altera_uart_stop_rx,
	.break_ctl = altera_uart_break_ctl,
	.startup = altera_uart_startup,
	.shutdown = altera_uart_shutdown,
	.set_termios = altera_uart_set_termios,
	.type = altera_uart_type,
	.request_port = altera_uart_request_port,
	.release_port = altera_uart_release_port,
	.config_port = altera_uart_config_port,
	.verify_port = altera_uart_verify_port,
	#ifdef CONFIG_CONSOLE_POLL
	.poll_get_char = altera_uart_poll_get_char,
	.poll_put_char = altera_uart_poll_put_char,
	#endif
	};

	static struct altera_uart altera_uart_ports[CONFIG_SERIAL_ALTERA_UART_MAXPORTS];

	#if defined(CONFIG_SERIAL_ALTERA_UART_CONSOLE)

	static void altera_uart_console_putc(struct uart_port *port, int c)
	{
	while (!(altera_uart_readl(port, ALTERA_UART_STATUS_REG) &
	ALTERA_UART_STATUS_TRDY_MSK))
	cpu_relax();

	writel(c, port->membase + ALTERA_UART_TXDATA_REG);
	}

	static void altera_uart_console_write(struct console co, const char s,
	unsigned int count)
	{
	struct uart_port *port = &(altera_uart_ports + co->index)->port;

	uart_console_write(port, s, count, altera_uart_console_putc);
	}

	static int __init altera_uart_console_setup(struct console co, char options)
	{
	struct uart_port *port;
	int baud = CONFIG_SERIAL_ALTERA_UART_BAUDRATE;
	int bits = 8;
	int parity = 'n';
	int flow = 'n';

	if (co->index < 0 \|\| co->index >= CONFIG_SERIAL_ALTERA_UART_MAXPORTS)
	return -EINVAL;
	port = &altera_uart_ports[co->index].port;
	if (!port->membase)
	return -ENODEV;

	if (options)
	uart_parse_options(options, &baud, &parity, &bits, &flow);

	return uart_set_options(port, co, baud, parity, bits, flow);
	}

	static struct uart_driver altera_uart_driver;

	static struct console altera_uart_console = {
	.name = "ttyAL",
	.write = altera_uart_console_write,
	.device = uart_console_device,
	.setup = altera_uart_console_setup,
	.flags = CON_PRINTBUFFER,
	.index = -1,
	.data = &altera_uart_driver,
	};

	static int __init altera_uart_console_init(void)
	{
	register_console(&altera_uart_console);
	return 0;
	}

	console_initcall(altera_uart_console_init);

	#define ALTERA_UART_CONSOLE (&altera_uart_console)

	#else

	#define ALTERA_UART_CONSOLE NULL

	#endif /* CONFIG_ALTERA_UART_CONSOLE */

	/*
	* Define the altera_uart UART driver structure.
	*/
	static struct uart_driver altera_uart_driver = {
	.owner = THIS_MODULE,
	.driver_name = DRV_NAME,
	.dev_name = "ttyAL",
	.major = SERIAL_ALTERA_MAJOR,
	.minor = SERIAL_ALTERA_MINOR,
	.nr = CONFIG_SERIAL_ALTERA_UART_MAXPORTS,
	.cons = ALTERA_UART_CONSOLE,
	};

	#ifdef CONFIG_OF
	static int altera_uart_get_of_uartclk(struct platform_device *pdev,
	struct uart_port *port)
	{
	int len;
	const __be32 *clk;

	clk = of_get_property(pdev->dev.of_node, "clock-frequency", &len);
	if (!clk \|\| len < sizeof(__be32))
	return -ENODEV;

	port->uartclk = be32_to_cpup(clk);

	return 0;
	}
	#else
	static int altera_uart_get_of_uartclk(struct platform_device *pdev,
	struct uart_port *port)
	{
	return -ENODEV;
	}
	#endif /* CONFIG_OF */

	static int altera_uart_probe(struct platform_device *pdev)
	{
	struct altera_uart_platform_uart *platp = dev_get_platdata(&pdev->dev);
	struct uart_port *port;
	struct resource *res_mem;
	struct resource *res_irq;
	int i = pdev->id;
	int ret;

	/* if id is -1 scan for a free id and use that one */
	if (i == -1) {
	for (i = 0; i < CONFIG_SERIAL_ALTERA_UART_MAXPORTS; i++)
	if (altera_uart_ports[i].port.mapbase == 0)
	break;
	}

	if (i < 0 \|\| i >= CONFIG_SERIAL_ALTERA_UART_MAXPORTS)
	return -EINVAL;

	port = &altera_uart_ports[i].port;

	res_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (res_mem)
	port->mapbase = res_mem->start;
	else if (platp)
	port->mapbase = platp->mapbase;
	else
	return -EINVAL;

	res_irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
	if (res_irq)
	port->irq = res_irq->start;
	else if (platp)
	port->irq = platp->irq;

	/* Check platform data first so we can override device node data */
	if (platp)
	port->uartclk = platp->uartclk;
	else {
	ret = altera_uart_get_of_uartclk(pdev, port);
	if (ret)
	return ret;
	}

	port->membase = ioremap(port->mapbase, ALTERA_UART_SIZE);
	if (!port->membase)
	return -ENOMEM;

	if (platp)
	port->regshift = platp->bus_shift;
	else
	port->regshift = 0;

	port->line = i;
	port->type = PORT_ALTERA_UART;
	port->iotype = SERIAL_IO_MEM;
	port->ops = &altera_uart_ops;
	port->flags = UPF_BOOT_AUTOCONF;

	platform_set_drvdata(pdev, port);

	uart_add_one_port(&altera_uart_driver, port);

	return 0;
	}

	static int altera_uart_remove(struct platform_device *pdev)
	{
	struct uart_port *port = platform_get_drvdata(pdev);

	if (port) {
	uart_remove_one_port(&altera_uart_driver, port);
	port->mapbase = 0;
	}

	return 0;
	}

	#ifdef CONFIG_OF
	static const struct of_device_id altera_uart_match[] = {
	{ .compatible = "ALTR,uart-1.0", },
	{ .compatible = "altr,uart-1.0", },
	{},
	};
	MODULE_DEVICE_TABLE(of, altera_uart_match);
	#endif /* CONFIG_OF */

	static struct platform_driver altera_uart_platform_driver = {
	.probe = altera_uart_probe,
	.remove = altera_uart_remove,
	.driver = {
	.name = DRV_NAME,
	.of_match_table = of_match_ptr(altera_uart_match),
	},
	};

	static int __init altera_uart_init(void)
	{
	int rc;

	rc = uart_register_driver(&altera_uart_driver);
	if (rc)
	return rc;
	rc = platform_driver_register(&altera_uart_platform_driver);
	if (rc)
	uart_unregister_driver(&altera_uart_driver);
	return rc;
	}

	static void __exit altera_uart_exit(void)
	{
	platform_driver_unregister(&altera_uart_platform_driver);
	uart_unregister_driver(&altera_uart_driver);
	}

	module_init(altera_uart_init);
	module_exit(altera_uart_exit);

	MODULE_DESCRIPTION("Altera UART driver");
	MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>");
	MODULE_LICENSE("GPL");
	MODULE_ALIAS("platform:" DRV_NAME);
	MODULE_ALIAS_CHARDEV_MAJOR(SERIAL_ALTERA_MAJOR);