arch/ia64/hp/sim/simserial.c - LeafOS-Devices/android_kernel_samsung_gta4xl - Gitiles

 /*
  * Simulated Serial Driver (fake serial)
  *
  * This driver is mostly used for bringup purposes and will go away.
  * It has a strong dependency on the system console. All outputs
  * are rerouted to the same facility as the one used by printk which, in our
  * case means sys_sim.c console (goes via the simulator).
  *
  * Copyright (C) 1999-2000, 2002-2003 Hewlett-Packard Co
  *	Stephane Eranian <eranian@hpl.hp.com>
  *	David Mosberger-Tang <davidm@hpl.hp.com>
  */

 #include <linux/init.h>
 #include <linux/errno.h>
 #include <linux/sched.h>
 #include <linux/tty.h>
 #include <linux/tty_flip.h>
 #include <linux/major.h>
 #include <linux/fcntl.h>
 #include <linux/mm.h>
 #include <linux/seq_file.h>
 #include <linux/slab.h>
 #include <linux/capability.h>
 #include <linux/circ_buf.h>
 #include <linux/console.h>
 #include <linux/irq.h>
 #include <linux/module.h>
 #include <linux/serial.h>
 #include <linux/sysrq.h>
 #include <linux/uaccess.h>

 #include <asm/hpsim.h>

 #include "hpsim_ssc.h"

 #undef SIMSERIAL_DEBUG	/* define this to get some debug information */

 #define KEYBOARD_INTR	3	/* must match with simulator! */

 #define NR_PORTS	1	/* only one port for now */

 struct serial_state {
 	struct tty_port port;
 	struct circ_buf xmit;
 	int irq;
 	int x_char;
 };

 static struct serial_state rs_table[NR_PORTS];

 struct tty_driver *hp_simserial_driver;

 static struct console *console;

 static void receive_chars(struct tty_struct *tty)
 {
 	struct tty_port *port = tty->port;
 	unsigned char ch;
 	static unsigned char seen_esc = 0;

 	while ( (ch = ia64_ssc(0, 0, 0, 0, SSC_GETCHAR)) ) {
 		if (ch == 27 && seen_esc == 0) {
 			seen_esc = 1;
 			continue;
 		} else if (seen_esc == 1 && ch == 'O') {
 			seen_esc = 2;
 			continue;
 		} else if (seen_esc == 2) {
 			if (ch == 'P') /* F1 */
 				show_state();
 #ifdef CONFIG_MAGIC_SYSRQ
 			if (ch == 'S') { /* F4 */
 				do {
 					ch = ia64_ssc(0, 0, 0, 0, SSC_GETCHAR);
 				} while (!ch);
 				handle_sysrq(ch);
 			}
 #endif
 			seen_esc = 0;
 			continue;
 		}
 		seen_esc = 0;

 		if (tty_insert_flip_char(port, ch, TTY_NORMAL) == 0)
 			break;
 	}
 	tty_flip_buffer_push(tty);
 }

 /*
  * This is the serial driver's interrupt routine for a single port
  */
 static irqreturn_t rs_interrupt_single(int irq, void *dev_id)
 {
 	struct serial_state *info = dev_id;
 	struct tty_struct *tty = tty_port_tty_get(&info->port);

 	if (!tty) {
 		printk(KERN_INFO "%s: tty=0 problem\n", __func__);
 		return IRQ_NONE;
 	}
 	/*
 	 * pretty simple in our case, because we only get interrupts
 	 * on inbound traffic
 	 */
 	receive_chars(tty);
 	tty_kref_put(tty);
 	return IRQ_HANDLED;
 }

 /*
  * -------------------------------------------------------------------
  * Here ends the serial interrupt routines.
  * -------------------------------------------------------------------
  */

 static int rs_put_char(struct tty_struct *tty, unsigned char ch)
 {
 	struct serial_state *info = tty->driver_data;
 	unsigned long flags;

 	if (!info->xmit.buf)
 		return 0;

 	local_irq_save(flags);
 	if (CIRC_SPACE(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE) == 0) {
 		local_irq_restore(flags);
 		return 0;
 	}
 	info->xmit.buf[info->xmit.head] = ch;
 	info->xmit.head = (info->xmit.head + 1) & (SERIAL_XMIT_SIZE-1);
 	local_irq_restore(flags);
 	return 1;
 }

 static void transmit_chars(struct tty_struct *tty, struct serial_state *info,
 		int *intr_done)
 {
 	int count;
 	unsigned long flags;

 	local_irq_save(flags);

 	if (info->x_char) {
 		char c = info->x_char;

 		console->write(console, &c, 1);

 		info->x_char = 0;

 		goto out;
 	}

 	if (info->xmit.head == info->xmit.tail || tty->stopped ||
 			tty->hw_stopped) {
 #ifdef SIMSERIAL_DEBUG
 		printk("transmit_chars: head=%d, tail=%d, stopped=%d\n",
 		       info->xmit.head, info->xmit.tail, tty->stopped);
 #endif
 		goto out;
 	}
 	/*
 	 * We removed the loop and try to do it in to chunks. We need
 	 * 2 operations maximum because it's a ring buffer.
 	 *
 	 * First from current to tail if possible.
 	 * Then from the beginning of the buffer until necessary
 	 */

 	count = min(CIRC_CNT(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE),
 		    SERIAL_XMIT_SIZE - info->xmit.tail);
 	console->write(console, info->xmit.buf+info->xmit.tail, count);

 	info->xmit.tail = (info->xmit.tail+count) & (SERIAL_XMIT_SIZE-1);

 	/*
 	 * We have more at the beginning of the buffer
 	 */
 	count = CIRC_CNT(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE);
 	if (count) {
 		console->write(console, info->xmit.buf, count);
 		info->xmit.tail += count;
 	}
 out:
 	local_irq_restore(flags);
 }

 static void rs_flush_chars(struct tty_struct *tty)
 {
 	struct serial_state *info = tty->driver_data;

 	if (info->xmit.head == info->xmit.tail || tty->stopped ||
 			tty->hw_stopped || !info->xmit.buf)
 		return;

 	transmit_chars(tty, info, NULL);
 }

 static int rs_write(struct tty_struct * tty,
 		    const unsigned char *buf, int count)
 {
 	struct serial_state *info = tty->driver_data;
 	int	c, ret = 0;
 	unsigned long flags;

 	if (!info->xmit.buf)
 		return 0;

 	local_irq_save(flags);
 	while (1) {
 		c = CIRC_SPACE_TO_END(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE);
 		if (count < c)
 			c = count;
 		if (c <= 0) {
 			break;
 		}
 		memcpy(info->xmit.buf + info->xmit.head, buf, c);
 		info->xmit.head = ((info->xmit.head + c) &
 				   (SERIAL_XMIT_SIZE-1));
 		buf += c;
 		count -= c;
 		ret += c;
 	}
 	local_irq_restore(flags);
 	/*
 	 * Hey, we transmit directly from here in our case
 	 */
 	if (CIRC_CNT(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE) &&
 			!tty->stopped && !tty->hw_stopped)
 		transmit_chars(tty, info, NULL);

 	return ret;
 }

 static int rs_write_room(struct tty_struct *tty)
 {
 	struct serial_state *info = tty->driver_data;

 	return CIRC_SPACE(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE);
 }

 static int rs_chars_in_buffer(struct tty_struct *tty)
 {
 	struct serial_state *info = tty->driver_data;

 	return CIRC_CNT(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE);
 }

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

 	local_irq_save(flags);
 	info->xmit.head = info->xmit.tail = 0;
 	local_irq_restore(flags);

 	tty_wakeup(tty);
 }

 /*
  * This function is used to send a high-priority XON/XOFF character to
  * the device
  */
 static void rs_send_xchar(struct tty_struct *tty, char ch)
 {
 	struct serial_state *info = tty->driver_data;

 	info->x_char = ch;
 	if (ch) {
 		/*
 		 * I guess we could call console->write() directly but
 		 * let's do that for now.
 		 */
 		transmit_chars(tty, info, NULL);
 	}
 }

 /*
  * ------------------------------------------------------------
  * rs_throttle()
  *
  * This routine is called by the upper-layer tty layer to signal that
  * incoming characters should be throttled.
  * ------------------------------------------------------------
  */
 static void rs_throttle(struct tty_struct * tty)
 {
 	if (I_IXOFF(tty))
 		rs_send_xchar(tty, STOP_CHAR(tty));

 	printk(KERN_INFO "simrs_throttle called\n");
 }

 static void rs_unthrottle(struct tty_struct * tty)
 {
 	struct serial_state *info = tty->driver_data;

 	if (I_IXOFF(tty)) {
 		if (info->x_char)
 			info->x_char = 0;
 		else
 			rs_send_xchar(tty, START_CHAR(tty));
 	}
 	printk(KERN_INFO "simrs_unthrottle called\n");
 }

 static int rs_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg)
 {
 	if ((cmd != TIOCGSERIAL) && (cmd != TIOCSSERIAL) &&
 	    (cmd != TIOCSERCONFIG) && (cmd != TIOCSERGSTRUCT) &&
 	    (cmd != TIOCMIWAIT)) {
 		if (tty->flags & (1 << TTY_IO_ERROR))
 		    return -EIO;
 	}

 	switch (cmd) {
 	case TIOCGSERIAL:
 	case TIOCSSERIAL:
 	case TIOCSERGSTRUCT:
 	case TIOCMIWAIT:
 		return 0;
 	case TIOCSERCONFIG:
 	case TIOCSERGETLSR: /* Get line status register */
 		return -EINVAL;
 	case TIOCSERGWILD:
 	case TIOCSERSWILD:
 		/* "setserial -W" is called in Debian boot */
 		printk (KERN_INFO "TIOCSER?WILD ioctl obsolete, ignored.\n");
 		return 0;
 	}
 	return -ENOIOCTLCMD;
 }

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

 static void rs_set_termios(struct tty_struct *tty, struct ktermios *old_termios)
 {
 	/* Handle turning off CRTSCTS */
 	if ((old_termios->c_cflag & CRTSCTS) &&
 	    !(tty->termios.c_cflag & CRTSCTS)) {
 		tty->hw_stopped = 0;
 	}
 }
 /*
  * This routine will shutdown a serial port; interrupts are disabled, and
  * DTR is dropped if the hangup on close termio flag is on.
  */
 static void shutdown(struct tty_port *port)
 {
 	struct serial_state *info = container_of(port, struct serial_state,
 			port);
 	unsigned long flags;

 	local_irq_save(flags);
 	if (info->irq)
 		free_irq(info->irq, info);

 	if (info->xmit.buf) {
 		free_page((unsigned long) info->xmit.buf);
 		info->xmit.buf = NULL;
 	}
 	local_irq_restore(flags);
 }

 static void rs_close(struct tty_struct *tty, struct file * filp)
 {
 	struct serial_state *info = tty->driver_data;

 	tty_port_close(&info->port, tty, filp);
 }

 static void rs_hangup(struct tty_struct *tty)
 {
 	struct serial_state *info = tty->driver_data;

 	rs_flush_buffer(tty);
 	tty_port_hangup(&info->port);
 }

 static int activate(struct tty_port *port, struct tty_struct *tty)
 {
 	struct serial_state *state = container_of(port, struct serial_state,
 			port);
 	unsigned long flags, page;
 	int retval = 0;

 	page = get_zeroed_page(GFP_KERNEL);
 	if (!page)
 		return -ENOMEM;

 	local_irq_save(flags);

 	if (state->xmit.buf)
 		free_page(page);
 	else
 		state->xmit.buf = (unsigned char *) page;

 	if (state->irq) {
 		retval = request_irq(state->irq, rs_interrupt_single, 0,
 				"simserial", state);
 		if (retval)
 			goto errout;
 	}

 	state->xmit.head = state->xmit.tail = 0;

 	/*
 	 * Set up the tty->alt_speed kludge
 	 */
 	if ((port->flags & ASYNC_SPD_MASK) == ASYNC_SPD_HI)
 		tty->alt_speed = 57600;
 	if ((port->flags & ASYNC_SPD_MASK) == ASYNC_SPD_VHI)
 		tty->alt_speed = 115200;
 	if ((port->flags & ASYNC_SPD_MASK) == ASYNC_SPD_SHI)
 		tty->alt_speed = 230400;
 	if ((port->flags & ASYNC_SPD_MASK) == ASYNC_SPD_WARP)
 		tty->alt_speed = 460800;

 errout:
 	local_irq_restore(flags);
 	return retval;
 }


 /*
  * This routine is called whenever a serial port is opened.  It
  * enables interrupts for a serial port, linking in its async structure into
  * the IRQ chain.   It also performs the serial-specific
  * initialization for the tty structure.
  */
 static int rs_open(struct tty_struct *tty, struct file * filp)
 {
 	struct serial_state *info = rs_table + tty->index;
 	struct tty_port *port = &info->port;

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

 	/*
 	 * figure out which console to use (should be one already)
 	 */
 	console = console_drivers;
 	while (console) {
 		if ((console->flags & CON_ENABLED) && console->write) break;
 		console = console->next;
 	}

 	return tty_port_open(port, tty, filp);
 }

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

 static int rs_proc_show(struct seq_file *m, void *v)
 {
 	int i;

 	seq_printf(m, "simserinfo:1.0\n");
 	for (i = 0; i < NR_PORTS; i++)
 		seq_printf(m, "%d: uart:16550 port:3F8 irq:%d\n",
 		       i, rs_table[i].irq);
 	return 0;
 }

 static int rs_proc_open(struct inode *inode, struct file *file)
 {
 	return single_open(file, rs_proc_show, NULL);
 }

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

 static const struct tty_operations hp_ops = {
 	.open = rs_open,
 	.close = rs_close,
 	.write = rs_write,
 	.put_char = rs_put_char,
 	.flush_chars = rs_flush_chars,
 	.write_room = rs_write_room,
 	.chars_in_buffer = rs_chars_in_buffer,
 	.flush_buffer = rs_flush_buffer,
 	.ioctl = rs_ioctl,
 	.throttle = rs_throttle,
 	.unthrottle = rs_unthrottle,
 	.send_xchar = rs_send_xchar,
 	.set_termios = rs_set_termios,
 	.hangup = rs_hangup,
 	.proc_fops = &rs_proc_fops,
 };

 static const struct tty_port_operations hp_port_ops = {
 	.activate = activate,
 	.shutdown = shutdown,
 };

 static int __init simrs_init(void)
 {
 	struct serial_state *state;
 	int retval;

 	if (!ia64_platform_is("hpsim"))
 		return -ENODEV;

 	hp_simserial_driver = alloc_tty_driver(NR_PORTS);
 	if (!hp_simserial_driver)
 		return -ENOMEM;

 	printk(KERN_INFO "SimSerial driver with no serial options enabled\n");

 	/* Initialize the tty_driver structure */

 	hp_simserial_driver->driver_name = "simserial";
 	hp_simserial_driver->name = "ttyS";
 	hp_simserial_driver->major = TTY_MAJOR;
 	hp_simserial_driver->minor_start = 64;
 	hp_simserial_driver->type = TTY_DRIVER_TYPE_SERIAL;
 	hp_simserial_driver->subtype = SERIAL_TYPE_NORMAL;
 	hp_simserial_driver->init_termios = tty_std_termios;
 	hp_simserial_driver->init_termios.c_cflag =
 		B9600 | CS8 | CREAD | HUPCL | CLOCAL;
 	hp_simserial_driver->flags = TTY_DRIVER_REAL_RAW;
 	tty_set_operations(hp_simserial_driver, &hp_ops);

 	state = rs_table;
 	tty_port_init(&state->port);
 	state->port.ops = &hp_port_ops;
 	state->port.close_delay = 0; /* XXX really 0? */

 	retval = hpsim_get_irq(KEYBOARD_INTR);
 	if (retval < 0) {
 		printk(KERN_ERR "%s: out of interrupt vectors!\n",
 				__func__);
 		goto err_free_tty;
 	}

 	state->irq = retval;

 	/* the port is imaginary */
 	printk(KERN_INFO "ttyS0 at 0x03f8 (irq = %d) is a 16550\n", state->irq);

 	tty_port_link_device(&state->port, hp_simserial_driver, 0);
 	retval = tty_register_driver(hp_simserial_driver);
 	if (retval) {
 		printk(KERN_ERR "Couldn't register simserial driver\n");
 		goto err_free_tty;
 	}

 	return 0;
 err_free_tty:
 	put_tty_driver(hp_simserial_driver);
 	tty_port_destroy(&state->port);
 	return retval;
 }

 #ifndef MODULE
 __initcall(simrs_init);
 #endif
	/*
	* Simulated Serial Driver (fake serial)
	*
	* This driver is mostly used for bringup purposes and will go away.
	* It has a strong dependency on the system console. All outputs
	* are rerouted to the same facility as the one used by printk which, in our
	* case means sys_sim.c console (goes via the simulator).
	*
	* Copyright (C) 1999-2000, 2002-2003 Hewlett-Packard Co
	* Stephane Eranian <eranian@hpl.hp.com>
	* David Mosberger-Tang <davidm@hpl.hp.com>
	*/

	#include <linux/init.h>
	#include <linux/errno.h>
	#include <linux/sched.h>
	#include <linux/tty.h>
	#include <linux/tty_flip.h>
	#include <linux/major.h>
	#include <linux/fcntl.h>
	#include <linux/mm.h>
	#include <linux/seq_file.h>
	#include <linux/slab.h>
	#include <linux/capability.h>
	#include <linux/circ_buf.h>
	#include <linux/console.h>
	#include <linux/irq.h>
	#include <linux/module.h>
	#include <linux/serial.h>
	#include <linux/sysrq.h>
	#include <linux/uaccess.h>

	#include <asm/hpsim.h>

	#include "hpsim_ssc.h"

	#undef SIMSERIAL_DEBUG /* define this to get some debug information */

	#define KEYBOARD_INTR 3 /* must match with simulator! */

	#define NR_PORTS 1 /* only one port for now */

	struct serial_state {
	struct tty_port port;
	struct circ_buf xmit;
	int irq;
	int x_char;
	};

	static struct serial_state rs_table[NR_PORTS];

	struct tty_driver *hp_simserial_driver;

	static struct console *console;

	static void receive_chars(struct tty_struct *tty)
	{
	struct tty_port *port = tty->port;
	unsigned char ch;
	static unsigned char seen_esc = 0;

	while ( (ch = ia64_ssc(0, 0, 0, 0, SSC_GETCHAR)) ) {
	if (ch == 27 && seen_esc == 0) {
	seen_esc = 1;
	continue;
	} else if (seen_esc == 1 && ch == 'O') {
	seen_esc = 2;
	continue;
	} else if (seen_esc == 2) {
	if (ch == 'P') /* F1 */
	show_state();
	#ifdef CONFIG_MAGIC_SYSRQ
	if (ch == 'S') { /* F4 */
	do {
	ch = ia64_ssc(0, 0, 0, 0, SSC_GETCHAR);
	} while (!ch);
	handle_sysrq(ch);
	}
	#endif
	seen_esc = 0;
	continue;
	}
	seen_esc = 0;

	if (tty_insert_flip_char(port, ch, TTY_NORMAL) == 0)
	break;
	}
	tty_flip_buffer_push(tty);
	}

	/*
	* This is the serial driver's interrupt routine for a single port
	*/
	static irqreturn_t rs_interrupt_single(int irq, void *dev_id)
	{
	struct serial_state *info = dev_id;
	struct tty_struct *tty = tty_port_tty_get(&info->port);

	if (!tty) {
	printk(KERN_INFO "%s: tty=0 problem\n", __func__);
	return IRQ_NONE;
	}
	/*
	* pretty simple in our case, because we only get interrupts
	* on inbound traffic
	*/
	receive_chars(tty);
	tty_kref_put(tty);
	return IRQ_HANDLED;
	}

	/*
	* -------------------------------------------------------------------
	* Here ends the serial interrupt routines.
	* -------------------------------------------------------------------
	*/

	static int rs_put_char(struct tty_struct *tty, unsigned char ch)
	{
	struct serial_state *info = tty->driver_data;
	unsigned long flags;

	if (!info->xmit.buf)
	return 0;

	local_irq_save(flags);
	if (CIRC_SPACE(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE) == 0) {
	local_irq_restore(flags);
	return 0;
	}
	info->xmit.buf[info->xmit.head] = ch;
	info->xmit.head = (info->xmit.head + 1) & (SERIAL_XMIT_SIZE-1);
	local_irq_restore(flags);
	return 1;
	}

	static void transmit_chars(struct tty_struct tty, struct serial_state info,
	int *intr_done)
	{
	int count;
	unsigned long flags;

	local_irq_save(flags);

	if (info->x_char) {
	char c = info->x_char;

	console->write(console, &c, 1);

	info->x_char = 0;

	goto out;
	}

	if (info->xmit.head == info->xmit.tail \|\| tty->stopped \|\|
	tty->hw_stopped) {
	#ifdef SIMSERIAL_DEBUG
	printk("transmit_chars: head=%d, tail=%d, stopped=%d\n",
	info->xmit.head, info->xmit.tail, tty->stopped);
	#endif
	goto out;
	}
	/*
	* We removed the loop and try to do it in to chunks. We need
	* 2 operations maximum because it's a ring buffer.
	*
	* First from current to tail if possible.
	* Then from the beginning of the buffer until necessary
	*/

	count = min(CIRC_CNT(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE),
	SERIAL_XMIT_SIZE - info->xmit.tail);
	console->write(console, info->xmit.buf+info->xmit.tail, count);

	info->xmit.tail = (info->xmit.tail+count) & (SERIAL_XMIT_SIZE-1);

	/*
	* We have more at the beginning of the buffer
	*/
	count = CIRC_CNT(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE);
	if (count) {
	console->write(console, info->xmit.buf, count);
	info->xmit.tail += count;
	}
	out:
	local_irq_restore(flags);
	}

	static void rs_flush_chars(struct tty_struct *tty)
	{
	struct serial_state *info = tty->driver_data;

	if (info->xmit.head == info->xmit.tail \|\| tty->stopped \|\|
	tty->hw_stopped \|\| !info->xmit.buf)
	return;

	transmit_chars(tty, info, NULL);
	}

	static int rs_write(struct tty_struct * tty,
	const unsigned char *buf, int count)
	{
	struct serial_state *info = tty->driver_data;
	int c, ret = 0;
	unsigned long flags;

	if (!info->xmit.buf)
	return 0;

	local_irq_save(flags);
	while (1) {
	c = CIRC_SPACE_TO_END(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE);
	if (count < c)
	c = count;
	if (c <= 0) {
	break;
	}
	memcpy(info->xmit.buf + info->xmit.head, buf, c);
	info->xmit.head = ((info->xmit.head + c) &
	(SERIAL_XMIT_SIZE-1));
	buf += c;
	count -= c;
	ret += c;
	}
	local_irq_restore(flags);
	/*
	* Hey, we transmit directly from here in our case
	*/
	if (CIRC_CNT(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE) &&
	!tty->stopped && !tty->hw_stopped)
	transmit_chars(tty, info, NULL);

	return ret;
	}

	static int rs_write_room(struct tty_struct *tty)
	{
	struct serial_state *info = tty->driver_data;

	return CIRC_SPACE(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE);
	}

	static int rs_chars_in_buffer(struct tty_struct *tty)
	{
	struct serial_state *info = tty->driver_data;

	return CIRC_CNT(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE);
	}

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

	local_irq_save(flags);
	info->xmit.head = info->xmit.tail = 0;
	local_irq_restore(flags);

	tty_wakeup(tty);
	}

	/*
	* This function is used to send a high-priority XON/XOFF character to
	* the device
	*/
	static void rs_send_xchar(struct tty_struct *tty, char ch)
	{
	struct serial_state *info = tty->driver_data;

	info->x_char = ch;
	if (ch) {
	/*
	* I guess we could call console->write() directly but
	* let's do that for now.
	*/
	transmit_chars(tty, info, NULL);
	}
	}

	/*
	* ------------------------------------------------------------
	* rs_throttle()
	*
	* This routine is called by the upper-layer tty layer to signal that
	* incoming characters should be throttled.
	* ------------------------------------------------------------
	*/
	static void rs_throttle(struct tty_struct * tty)
	{
	if (I_IXOFF(tty))
	rs_send_xchar(tty, STOP_CHAR(tty));

	printk(KERN_INFO "simrs_throttle called\n");
	}

	static void rs_unthrottle(struct tty_struct * tty)
	{
	struct serial_state *info = tty->driver_data;

	if (I_IXOFF(tty)) {
	if (info->x_char)
	info->x_char = 0;
	else
	rs_send_xchar(tty, START_CHAR(tty));
	}
	printk(KERN_INFO "simrs_unthrottle called\n");
	}

	static int rs_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg)
	{
	if ((cmd != TIOCGSERIAL) && (cmd != TIOCSSERIAL) &&
	(cmd != TIOCSERCONFIG) && (cmd != TIOCSERGSTRUCT) &&
	(cmd != TIOCMIWAIT)) {
	if (tty->flags & (1 << TTY_IO_ERROR))
	return -EIO;
	}

	switch (cmd) {
	case TIOCGSERIAL:
	case TIOCSSERIAL:
	case TIOCSERGSTRUCT:
	case TIOCMIWAIT:
	return 0;
	case TIOCSERCONFIG:
	case TIOCSERGETLSR: /* Get line status register */
	return -EINVAL;
	case TIOCSERGWILD:
	case TIOCSERSWILD:
	/* "setserial -W" is called in Debian boot */
	printk (KERN_INFO "TIOCSER?WILD ioctl obsolete, ignored.\n");
	return 0;
	}
	return -ENOIOCTLCMD;
	}

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

	static void rs_set_termios(struct tty_struct tty, struct ktermios old_termios)
	{
	/* Handle turning off CRTSCTS */
	if ((old_termios->c_cflag & CRTSCTS) &&
	!(tty->termios.c_cflag & CRTSCTS)) {
	tty->hw_stopped = 0;
	}
	}
	/*
	* This routine will shutdown a serial port; interrupts are disabled, and
	* DTR is dropped if the hangup on close termio flag is on.
	*/
	static void shutdown(struct tty_port *port)
	{
	struct serial_state *info = container_of(port, struct serial_state,
	port);
	unsigned long flags;

	local_irq_save(flags);
	if (info->irq)
	free_irq(info->irq, info);

	if (info->xmit.buf) {
	free_page((unsigned long) info->xmit.buf);
	info->xmit.buf = NULL;
	}
	local_irq_restore(flags);
	}

	static void rs_close(struct tty_struct tty, struct file filp)
	{
	struct serial_state *info = tty->driver_data;

	tty_port_close(&info->port, tty, filp);
	}

	static void rs_hangup(struct tty_struct *tty)
	{
	struct serial_state *info = tty->driver_data;

	rs_flush_buffer(tty);
	tty_port_hangup(&info->port);
	}

	static int activate(struct tty_port port, struct tty_struct tty)
	{
	struct serial_state *state = container_of(port, struct serial_state,
	port);
	unsigned long flags, page;
	int retval = 0;

	page = get_zeroed_page(GFP_KERNEL);
	if (!page)
	return -ENOMEM;

	local_irq_save(flags);

	if (state->xmit.buf)
	free_page(page);
	else
	state->xmit.buf = (unsigned char *) page;

	if (state->irq) {
	retval = request_irq(state->irq, rs_interrupt_single, 0,
	"simserial", state);
	if (retval)
	goto errout;
	}

	state->xmit.head = state->xmit.tail = 0;

	/*
	* Set up the tty->alt_speed kludge
	*/
	if ((port->flags & ASYNC_SPD_MASK) == ASYNC_SPD_HI)
	tty->alt_speed = 57600;
	if ((port->flags & ASYNC_SPD_MASK) == ASYNC_SPD_VHI)
	tty->alt_speed = 115200;
	if ((port->flags & ASYNC_SPD_MASK) == ASYNC_SPD_SHI)
	tty->alt_speed = 230400;
	if ((port->flags & ASYNC_SPD_MASK) == ASYNC_SPD_WARP)
	tty->alt_speed = 460800;

	errout:
	local_irq_restore(flags);
	return retval;
	}


	/*
	* This routine is called whenever a serial port is opened. It
	* enables interrupts for a serial port, linking in its async structure into
	* the IRQ chain. It also performs the serial-specific
	* initialization for the tty structure.
	*/
	static int rs_open(struct tty_struct tty, struct file filp)
	{
	struct serial_state *info = rs_table + tty->index;
	struct tty_port *port = &info->port;

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

	/*
	* figure out which console to use (should be one already)
	*/
	console = console_drivers;
	while (console) {
	if ((console->flags & CON_ENABLED) && console->write) break;
	console = console->next;
	}

	return tty_port_open(port, tty, filp);
	}

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

	static int rs_proc_show(struct seq_file m, void v)
	{
	int i;

	seq_printf(m, "simserinfo:1.0\n");
	for (i = 0; i < NR_PORTS; i++)
	seq_printf(m, "%d: uart:16550 port:3F8 irq:%d\n",
	i, rs_table[i].irq);
	return 0;
	}

	static int rs_proc_open(struct inode inode, struct file file)
	{
	return single_open(file, rs_proc_show, NULL);
	}

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

	static const struct tty_operations hp_ops = {
	.open = rs_open,
	.close = rs_close,
	.write = rs_write,
	.put_char = rs_put_char,
	.flush_chars = rs_flush_chars,
	.write_room = rs_write_room,
	.chars_in_buffer = rs_chars_in_buffer,
	.flush_buffer = rs_flush_buffer,
	.ioctl = rs_ioctl,
	.throttle = rs_throttle,
	.unthrottle = rs_unthrottle,
	.send_xchar = rs_send_xchar,
	.set_termios = rs_set_termios,
	.hangup = rs_hangup,
	.proc_fops = &rs_proc_fops,
	};

	static const struct tty_port_operations hp_port_ops = {
	.activate = activate,
	.shutdown = shutdown,
	};

	static int __init simrs_init(void)
	{
	struct serial_state *state;
	int retval;

	if (!ia64_platform_is("hpsim"))
	return -ENODEV;

	hp_simserial_driver = alloc_tty_driver(NR_PORTS);
	if (!hp_simserial_driver)
	return -ENOMEM;

	printk(KERN_INFO "SimSerial driver with no serial options enabled\n");

	/* Initialize the tty_driver structure */

	hp_simserial_driver->driver_name = "simserial";
	hp_simserial_driver->name = "ttyS";
	hp_simserial_driver->major = TTY_MAJOR;
	hp_simserial_driver->minor_start = 64;
	hp_simserial_driver->type = TTY_DRIVER_TYPE_SERIAL;
	hp_simserial_driver->subtype = SERIAL_TYPE_NORMAL;
	hp_simserial_driver->init_termios = tty_std_termios;
	hp_simserial_driver->init_termios.c_cflag =
	B9600 \| CS8 \| CREAD \| HUPCL \| CLOCAL;
	hp_simserial_driver->flags = TTY_DRIVER_REAL_RAW;
	tty_set_operations(hp_simserial_driver, &hp_ops);

	state = rs_table;
	tty_port_init(&state->port);
	state->port.ops = &hp_port_ops;
	state->port.close_delay = 0; /* XXX really 0? */

	retval = hpsim_get_irq(KEYBOARD_INTR);
	if (retval < 0) {
	printk(KERN_ERR "%s: out of interrupt vectors!\n",
	__func__);
	goto err_free_tty;
	}

	state->irq = retval;

	/* the port is imaginary */
	printk(KERN_INFO "ttyS0 at 0x03f8 (irq = %d) is a 16550\n", state->irq);

	tty_port_link_device(&state->port, hp_simserial_driver, 0);
	retval = tty_register_driver(hp_simserial_driver);
	if (retval) {
	printk(KERN_ERR "Couldn't register simserial driver\n");
	goto err_free_tty;
	}

	return 0;
	err_free_tty:
	put_tty_driver(hp_simserial_driver);
	tty_port_destroy(&state->port);
	return retval;
	}

	#ifndef MODULE
	__initcall(simrs_init);
	#endif