/*
   * uartlite.c: Serial driver for Xilinx uartlite serial controller
   *

   * Copyright (C) 2006 Peter Korsgaard <jacmet@sunsite.dk>
   * Copyright (C) 2007 Secret Lab Technologies Ltd.

   *
   * This file is licensed under the terms of the GNU General Public License
   * version 2.  This program is licensed "as is" without any warranty of any
   * kind, whether express or implied.
   */
  
  #include <linux/platform_device.h>
  #include <linux/module.h>
  #include <linux/console.h>
  #include <linux/serial.h>
  #include <linux/serial_core.h>
  #include <linux/tty.h>
  #include <linux/delay.h>
  #include <linux/interrupt.h>

  #include <linux/init.h>

  #include <asm/io.h>

  #if defined(CONFIG_OF)

  #include <linux/of.h>

  #include <linux/of_device.h>
  #include <linux/of_platform.h>

  
  /* Match table for of_platform binding */
  static struct of_device_id ulite_of_match[] __devinitdata = {
  	{ .compatible = "xlnx,opb-uartlite-1.00.b", },
  	{ .compatible = "xlnx,xps-uartlite-1.00.a", },
  	{}
  };
  MODULE_DEVICE_TABLE(of, ulite_of_match);

  #endif

  #define ULITE_NAME		"ttyUL"

  #define ULITE_MAJOR		204
  #define ULITE_MINOR		187
  #define ULITE_NR_UARTS		4

  /* ---------------------------------------------------------------------
   * Register definitions
   *
   * For register details see datasheet:
   * http://www.xilinx.com/bvdocs/ipcenter/data_sheet/opb_uartlite.pdf
   */

  #define ULITE_RX		0x00
  #define ULITE_TX		0x04
  #define ULITE_STATUS		0x08
  #define ULITE_CONTROL		0x0c
  
  #define ULITE_REGION		16
  
  #define ULITE_STATUS_RXVALID	0x01
  #define ULITE_STATUS_RXFULL	0x02
  #define ULITE_STATUS_TXEMPTY	0x04
  #define ULITE_STATUS_TXFULL	0x08
  #define ULITE_STATUS_IE		0x10
  #define ULITE_STATUS_OVERRUN	0x20
  #define ULITE_STATUS_FRAME	0x40
  #define ULITE_STATUS_PARITY	0x80
  
  #define ULITE_CONTROL_RST_TX	0x01
  #define ULITE_CONTROL_RST_RX	0x02
  #define ULITE_CONTROL_IE	0x10

  static struct uart_port ulite_ports[ULITE_NR_UARTS];

  /* ---------------------------------------------------------------------
   * Core UART driver operations
   */

  static int ulite_receive(struct uart_port *port, int stat)
  {

  	struct tty_struct *tty = port->info->port.tty;

  	unsigned char ch = 0;
  	char flag = TTY_NORMAL;
  
  	if ((stat & (ULITE_STATUS_RXVALID | ULITE_STATUS_OVERRUN
  		     | ULITE_STATUS_FRAME)) == 0)
  		return 0;
  
  	/* stats */
  	if (stat & ULITE_STATUS_RXVALID) {
  		port->icount.rx++;

  		ch = readb(port->membase + ULITE_RX);

  
  		if (stat & ULITE_STATUS_PARITY)
  			port->icount.parity++;
  	}
  
  	if (stat & ULITE_STATUS_OVERRUN)
  		port->icount.overrun++;
  
  	if (stat & ULITE_STATUS_FRAME)
  		port->icount.frame++;
  
  
  	/* drop byte with parity error if IGNPAR specificed */
  	if (stat & port->ignore_status_mask & ULITE_STATUS_PARITY)
  		stat &= ~ULITE_STATUS_RXVALID;
  
  	stat &= port->read_status_mask;
  
  	if (stat & ULITE_STATUS_PARITY)
  		flag = TTY_PARITY;
  
  
  	stat &= ~port->ignore_status_mask;
  
  	if (stat & ULITE_STATUS_RXVALID)
  		tty_insert_flip_char(tty, ch, flag);
  
  	if (stat & ULITE_STATUS_FRAME)
  		tty_insert_flip_char(tty, 0, TTY_FRAME);
  
  	if (stat & ULITE_STATUS_OVERRUN)
  		tty_insert_flip_char(tty, 0, TTY_OVERRUN);
  
  	return 1;
  }
  
  static int ulite_transmit(struct uart_port *port, int stat)
  {
  	struct circ_buf *xmit  = &port->info->xmit;
  
  	if (stat & ULITE_STATUS_TXFULL)
  		return 0;
  
  	if (port->x_char) {

  		writeb(port->x_char, port->membase + ULITE_TX);

  		port->x_char = 0;
  		port->icount.tx++;
  		return 1;
  	}
  
  	if (uart_circ_empty(xmit) || uart_tx_stopped(port))
  		return 0;

  	writeb(xmit->buf[xmit->tail], port->membase + ULITE_TX);

  	xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE-1);
  	port->icount.tx++;
  
  	/* wake up */
  	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
  		uart_write_wakeup(port);
  
  	return 1;
  }
  
  static irqreturn_t ulite_isr(int irq, void *dev_id)
  {

  	struct uart_port *port = dev_id;

  	int busy;
  
  	do {

  		int stat = readb(port->membase + ULITE_STATUS);

  		busy  = ulite_receive(port, stat);
  		busy |= ulite_transmit(port, stat);
  	} while (busy);

  	tty_flip_buffer_push(port->info->port.tty);

  
  	return IRQ_HANDLED;
  }
  
  static unsigned int ulite_tx_empty(struct uart_port *port)
  {
  	unsigned long flags;
  	unsigned int ret;
  
  	spin_lock_irqsave(&port->lock, flags);

  	ret = readb(port->membase + ULITE_STATUS);

  	spin_unlock_irqrestore(&port->lock, flags);
  
  	return ret & ULITE_STATUS_TXEMPTY ? TIOCSER_TEMT : 0;
  }
  
  static unsigned int ulite_get_mctrl(struct uart_port *port)
  {
  	return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;
  }
  
  static void ulite_set_mctrl(struct uart_port *port, unsigned int mctrl)
  {
  	/* N/A */
  }
  
  static void ulite_stop_tx(struct uart_port *port)
  {
  	/* N/A */
  }
  
  static void ulite_start_tx(struct uart_port *port)
  {

  	ulite_transmit(port, readb(port->membase + ULITE_STATUS));

  }
  
  static void ulite_stop_rx(struct uart_port *port)
  {
  	/* don't forward any more data (like !CREAD) */
  	port->ignore_status_mask = ULITE_STATUS_RXVALID | ULITE_STATUS_PARITY
  		| ULITE_STATUS_FRAME | ULITE_STATUS_OVERRUN;
  }
  
  static void ulite_enable_ms(struct uart_port *port)
  {
  	/* N/A */
  }
  
  static void ulite_break_ctl(struct uart_port *port, int ctl)
  {
  	/* N/A */
  }
  
  static int ulite_startup(struct uart_port *port)
  {
  	int ret;
  
  	ret = request_irq(port->irq, ulite_isr,
  			  IRQF_DISABLED | IRQF_SAMPLE_RANDOM, "uartlite", port);
  	if (ret)
  		return ret;

  	writeb(ULITE_CONTROL_RST_RX | ULITE_CONTROL_RST_TX,
  	       port->membase + ULITE_CONTROL);
  	writeb(ULITE_CONTROL_IE, port->membase + ULITE_CONTROL);

  
  	return 0;
  }
  
  static void ulite_shutdown(struct uart_port *port)
  {

  	writeb(0, port->membase + ULITE_CONTROL);
  	readb(port->membase + ULITE_CONTROL); /* dummy */

  	free_irq(port->irq, port);
  }

  static void ulite_set_termios(struct uart_port *port, struct ktermios *termios,
  			      struct ktermios *old)

  {
  	unsigned long flags;
  	unsigned int baud;
  
  	spin_lock_irqsave(&port->lock, flags);
  
  	port->read_status_mask = ULITE_STATUS_RXVALID | ULITE_STATUS_OVERRUN
  		| ULITE_STATUS_TXFULL;
  
  	if (termios->c_iflag & INPCK)
  		port->read_status_mask |=
  			ULITE_STATUS_PARITY | ULITE_STATUS_FRAME;
  
  	port->ignore_status_mask = 0;
  	if (termios->c_iflag & IGNPAR)
  		port->ignore_status_mask |= ULITE_STATUS_PARITY
  			| ULITE_STATUS_FRAME | ULITE_STATUS_OVERRUN;
  
  	/* ignore all characters if CREAD is not set */
  	if ((termios->c_cflag & CREAD) == 0)
  		port->ignore_status_mask |=
  			ULITE_STATUS_RXVALID | ULITE_STATUS_PARITY
  			| ULITE_STATUS_FRAME | ULITE_STATUS_OVERRUN;
  
  	/* update timeout */
  	baud = uart_get_baud_rate(port, termios, old, 0, 460800);
  	uart_update_timeout(port, termios->c_cflag, baud);
  
  	spin_unlock_irqrestore(&port->lock, flags);
  }
  
  static const char *ulite_type(struct uart_port *port)
  {
  	return port->type == PORT_UARTLITE ? "uartlite" : NULL;
  }
  
  static void ulite_release_port(struct uart_port *port)
  {
  	release_mem_region(port->mapbase, ULITE_REGION);
  	iounmap(port->membase);

  	port->membase = NULL;

  }
  
  static int ulite_request_port(struct uart_port *port)
  {

  	pr_debug("ulite console: port=%p; port->mapbase=%llx
  ",
  		 port, (unsigned long long) port->mapbase);

  	if (!request_mem_region(port->mapbase, ULITE_REGION, "uartlite")) {
  		dev_err(port->dev, "Memory region busy
  ");
  		return -EBUSY;
  	}
  
  	port->membase = ioremap(port->mapbase, ULITE_REGION);
  	if (!port->membase) {
  		dev_err(port->dev, "Unable to map registers
  ");
  		release_mem_region(port->mapbase, ULITE_REGION);
  		return -EBUSY;
  	}
  
  	return 0;
  }
  
  static void ulite_config_port(struct uart_port *port, int flags)
  {

  	if (!ulite_request_port(port))
  		port->type = PORT_UARTLITE;

  }
  
  static int ulite_verify_port(struct uart_port *port, struct serial_struct *ser)
  {
  	/* we don't want the core code to modify any port params */
  	return -EINVAL;
  }
  
  static struct uart_ops ulite_ops = {
  	.tx_empty	= ulite_tx_empty,
  	.set_mctrl	= ulite_set_mctrl,
  	.get_mctrl	= ulite_get_mctrl,
  	.stop_tx	= ulite_stop_tx,
  	.start_tx	= ulite_start_tx,
  	.stop_rx	= ulite_stop_rx,
  	.enable_ms	= ulite_enable_ms,
  	.break_ctl	= ulite_break_ctl,
  	.startup	= ulite_startup,
  	.shutdown	= ulite_shutdown,
  	.set_termios	= ulite_set_termios,
  	.type		= ulite_type,
  	.release_port	= ulite_release_port,
  	.request_port	= ulite_request_port,
  	.config_port	= ulite_config_port,
  	.verify_port	= ulite_verify_port
  };

  /* ---------------------------------------------------------------------
   * Console driver operations
   */

  #ifdef CONFIG_SERIAL_UARTLITE_CONSOLE
  static void ulite_console_wait_tx(struct uart_port *port)
  {
  	int i;

  	u8 val;

  	/* Spin waiting for TX fifo to have space available */
  	for (i = 0; i < 100000; i++) {
  		val = readb(port->membase + ULITE_STATUS);
  		if ((val & ULITE_STATUS_TXFULL) == 0)

  			break;

  		cpu_relax();

  	}
  }
  
  static void ulite_console_putchar(struct uart_port *port, int ch)
  {
  	ulite_console_wait_tx(port);

  	writeb(ch, port->membase + ULITE_TX);

  }
  
  static void ulite_console_write(struct console *co, const char *s,
  				unsigned int count)
  {

  	struct uart_port *port = &ulite_ports[co->index];

  	unsigned long flags;
  	unsigned int ier;
  	int locked = 1;
  
  	if (oops_in_progress) {
  		locked = spin_trylock_irqsave(&port->lock, flags);
  	} else
  		spin_lock_irqsave(&port->lock, flags);
  
  	/* save and disable interrupt */

  	ier = readb(port->membase + ULITE_STATUS) & ULITE_STATUS_IE;
  	writeb(0, port->membase + ULITE_CONTROL);

  
  	uart_console_write(port, s, count, ulite_console_putchar);
  
  	ulite_console_wait_tx(port);
  
  	/* restore interrupt state */
  	if (ier)

  		writeb(ULITE_CONTROL_IE, port->membase + ULITE_CONTROL);

  
  	if (locked)
  		spin_unlock_irqrestore(&port->lock, flags);
  }
  
  static int __init ulite_console_setup(struct console *co, char *options)
  {
  	struct uart_port *port;
  	int baud = 9600;
  	int bits = 8;
  	int parity = 'n';
  	int flow = 'n';
  
  	if (co->index < 0 || co->index >= ULITE_NR_UARTS)
  		return -EINVAL;

  	port = &ulite_ports[co->index];

  	/* Has the device been initialized yet? */

  	if (!port->mapbase) {
  		pr_debug("console on ttyUL%i not present
  ", co->index);
  		return -ENODEV;
  	}

  	/* not initialized yet? */

  	if (!port->membase) {

  		if (ulite_request_port(port))
  			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 ulite_uart_driver;
  
  static struct console ulite_console = {

  	.name	= ULITE_NAME,

  	.write	= ulite_console_write,
  	.device	= uart_console_device,
  	.setup	= ulite_console_setup,
  	.flags	= CON_PRINTBUFFER,
  	.index	= -1, /* Specified on the cmdline (e.g. console=ttyUL0 ) */
  	.data	= &ulite_uart_driver,
  };
  
  static int __init ulite_console_init(void)
  {
  	register_console(&ulite_console);
  	return 0;
  }
  
  console_initcall(ulite_console_init);
  
  #endif /* CONFIG_SERIAL_UARTLITE_CONSOLE */
  
  static struct uart_driver ulite_uart_driver = {
  	.owner		= THIS_MODULE,
  	.driver_name	= "uartlite",

  	.dev_name	= ULITE_NAME,

  	.major		= ULITE_MAJOR,
  	.minor		= ULITE_MINOR,
  	.nr		= ULITE_NR_UARTS,
  #ifdef CONFIG_SERIAL_UARTLITE_CONSOLE
  	.cons		= &ulite_console,
  #endif
  };

  /* ---------------------------------------------------------------------
   * Port assignment functions (mapping devices to uart_port structures)
   */
  
  /** ulite_assign: register a uartlite device with the driver
   *
   * @dev: pointer to device structure
   * @id: requested id number.  Pass -1 for automatic port assignment
   * @base: base address of uartlite registers
   * @irq: irq number for uartlite
   *
   * Returns: 0 on success, <0 otherwise
   */

  static int __devinit ulite_assign(struct device *dev, int id, u32 base, int irq)

  {

  	struct uart_port *port;

  	int rc;

  	/* if id = -1; then scan for a free id and use that */
  	if (id < 0) {
  		for (id = 0; id < ULITE_NR_UARTS; id++)
  			if (ulite_ports[id].mapbase == 0)
  				break;
  	}
  	if (id < 0 || id >= ULITE_NR_UARTS) {
  		dev_err(dev, "%s%i too large
  ", ULITE_NAME, id);

  		return -EINVAL;

  	}

  	if ((ulite_ports[id].mapbase) && (ulite_ports[id].mapbase != base)) {

  		dev_err(dev, "cannot assign to %s%i; it is already in use
  ",
  			ULITE_NAME, id);

  		return -EBUSY;

  	}

  	port = &ulite_ports[id];

  	spin_lock_init(&port->lock);
  	port->fifosize = 16;
  	port->regshift = 2;
  	port->iotype = UPIO_MEM;
  	port->iobase = 1; /* mark port in use */
  	port->mapbase = base;
  	port->membase = NULL;
  	port->ops = &ulite_ops;
  	port->irq = irq;
  	port->flags = UPF_BOOT_AUTOCONF;
  	port->dev = dev;
  	port->type = PORT_UNKNOWN;
  	port->line = id;
  
  	dev_set_drvdata(dev, port);
  
  	/* Register the port */
  	rc = uart_add_one_port(&ulite_uart_driver, port);
  	if (rc) {
  		dev_err(dev, "uart_add_one_port() failed; err=%i
  ", rc);
  		port->mapbase = 0;
  		dev_set_drvdata(dev, NULL);
  		return rc;
  	}

  	return 0;
  }

  /** ulite_release: register a uartlite device with the driver
   *
   * @dev: pointer to device structure
   */

  static int __devexit ulite_release(struct device *dev)

  {
  	struct uart_port *port = dev_get_drvdata(dev);
  	int rc = 0;

  	if (port) {
  		rc = uart_remove_one_port(&ulite_uart_driver, port);
  		dev_set_drvdata(dev, NULL);
  		port->mapbase = 0;
  	}

  	return rc;

  }

  /* ---------------------------------------------------------------------
   * Platform bus binding
   */

  static int __devinit ulite_probe(struct platform_device *pdev)

  {

  	struct resource *res, *res2;

  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  	if (!res)
  		return -ENODEV;

  	res2 = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
  	if (!res2)
  		return -ENODEV;

  	return ulite_assign(&pdev->dev, pdev->id, res->start, res2->start);
  }

  static int __devexit ulite_remove(struct platform_device *pdev)

  {
  	return ulite_release(&pdev->dev);

  }

  /* work with hotplug and coldplug */
  MODULE_ALIAS("platform:uartlite");

  static struct platform_driver ulite_platform_driver = {
  	.probe	= ulite_probe,

  	.remove	= __devexit_p(ulite_remove),

  	.driver	= {
  		   .owner = THIS_MODULE,
  		   .name  = "uartlite",
  		   },
  };

  /* ---------------------------------------------------------------------

   * OF bus bindings
   */
  #if defined(CONFIG_OF)
  static int __devinit
  ulite_of_probe(struct of_device *op, const struct of_device_id *match)
  {
  	struct resource res;
  	const unsigned int *id;
  	int irq, rc;

  	dev_dbg(&op->dev, "%s(%p, %p)
  ", __func__, op, match);

  
  	rc = of_address_to_resource(op->node, 0, &res);
  	if (rc) {

  		dev_err(&op->dev, "invalid address
  ");

  		return rc;
  	}
  
  	irq = irq_of_parse_and_map(op->node, 0);
  
  	id = of_get_property(op->node, "port-number", NULL);

  	return ulite_assign(&op->dev, id ? *id : -1, res.start+3, irq);

  }
  
  static int __devexit ulite_of_remove(struct of_device *op)
  {
  	return ulite_release(&op->dev);
  }

  static struct of_platform_driver ulite_of_driver = {
  	.owner = THIS_MODULE,
  	.name = "uartlite",
  	.match_table = ulite_of_match,
  	.probe = ulite_of_probe,
  	.remove = __devexit_p(ulite_of_remove),
  	.driver = {
  		.name = "uartlite",
  	},
  };
  
  /* Registration helpers to keep the number of #ifdefs to a minimum */
  static inline int __init ulite_of_register(void)
  {
  	pr_debug("uartlite: calling of_register_platform_driver()
  ");
  	return of_register_platform_driver(&ulite_of_driver);
  }
  
  static inline void __exit ulite_of_unregister(void)
  {
  	of_unregister_platform_driver(&ulite_of_driver);
  }
  #else /* CONFIG_OF */
  /* CONFIG_OF not enabled; do nothing helpers */
  static inline int __init ulite_of_register(void) { return 0; }
  static inline void __exit ulite_of_unregister(void) { }
  #endif /* CONFIG_OF */
  
  /* ---------------------------------------------------------------------

   * Module setup/teardown
   */

  int __init ulite_init(void)
  {
  	int ret;

  	pr_debug("uartlite: calling uart_register_driver()
  ");

  	ret = uart_register_driver(&ulite_uart_driver);
  	if (ret)

  		goto err_uart;
  
  	ret = ulite_of_register();
  	if (ret)
  		goto err_of;

  	pr_debug("uartlite: calling platform_driver_register()
  ");

  	ret = platform_driver_register(&ulite_platform_driver);
  	if (ret)

  		goto err_plat;
  
  	return 0;

  err_plat:
  	ulite_of_unregister();
  err_of:
  	uart_unregister_driver(&ulite_uart_driver);
  err_uart:
  	printk(KERN_ERR "registering uartlite driver failed: err=%i", ret);

  	return ret;
  }
  
  void __exit ulite_exit(void)
  {
  	platform_driver_unregister(&ulite_platform_driver);

  	ulite_of_unregister();

  	uart_unregister_driver(&ulite_uart_driver);
  }
  
  module_init(ulite_init);
  module_exit(ulite_exit);
  
  MODULE_AUTHOR("Peter Korsgaard <jacmet@sunsite.dk>");
  MODULE_DESCRIPTION("Xilinx uartlite serial driver");
  MODULE_LICENSE("GPL");