/*
 * 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). The code hereafter
 * is completely leveraged from the serial.c driver.
 *
 * Copyright (C) 1999-2000, 2002-2003 Hewlett-Packard Co
 *	Stephane Eranian <eranian@hpl.hp.com>
 *	David Mosberger-Tang <davidm@hpl.hp.com>
 *
 * 02/04/00 D. Mosberger	Merged in serial.c bug fixes in rs_close().
 * 02/25/00 D. Mosberger	Synced up with 2.3.99pre-5 version of serial.c.
 * 07/30/02 D. Mosberger	Replace sti()/cli() with explicit spinlocks & local irq masking
 */

#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/module.h>
#include <linux/serial.h>
#include <linux/sysrq.h>

#include <asm/irq.h>
#include <asm/hpsim.h>
#include <asm/hw_irq.h>
#include <asm/uaccess.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 tport;
	struct circ_buf xmit;
	int irq;
	int x_char;
};

static char *serial_name = "SimSerial driver";
static char *serial_version = "0.6";

static struct serial_state rs_table[NR_PORTS];

struct tty_driver *hp_simserial_driver;

static struct console *console;

extern struct console *console_drivers; /* from kernel/printk.c */

/*
 * ------------------------------------------------------------
 * rs_stop() and rs_start()
 *
 * This routines are called before setting or resetting tty->stopped.
 * They enable or disable transmitter interrupts, as necessary.
 * ------------------------------------------------------------
 */
static void rs_stop(struct tty_struct *tty)
{
#ifdef SIMSERIAL_DEBUG
	printk("rs_stop: tty->stopped=%d tty->hw_stopped=%d tty->flow_stopped=%d\n",
		tty->stopped, tty->hw_stopped, tty->flow_stopped);
#endif

}

static void rs_start(struct tty_struct *tty)
{
#ifdef SIMSERIAL_DEBUG
	printk("rs_start: tty->stopped=%d tty->hw_stopped=%d tty->flow_stopped=%d\n",
		tty->stopped, tty->hw_stopped, tty->flow_stopped);
#endif
}

static  void receive_chars(struct tty_struct *tty)
{
	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(tty, 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;

	if (!info->tport.tty) {
		printk(KERN_INFO "simrs_interrupt_single: info|tty=0 info=%p problem\n", info);
		return IRQ_NONE;
	}
	/*
	 * pretty simple in our case, because we only get interrupts
	 * on inbound traffic
	 */
	receive_chars(info->tport.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 (!tty || !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