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console.c

/*
 * arch/xtensa/platform-iss/console.c
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (C) 2001-2005 Tensilica Inc.
 *   Authors      Christian Zankel, Joe Taylor
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/console.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/major.h>
#include <linux/param.h>
#include <linux/serial.h>
#include <linux/serialP.h>

#include <asm/uaccess.h>
#include <asm/irq.h>

#include <asm/platform/simcall.h>

#include <linux/tty.h>
#include <linux/tty_flip.h>

#ifdef SERIAL_INLINE
#define _INLINE_ inline
#endif

#define SERIAL_MAX_NUM_LINES 1
#define SERIAL_TIMER_VALUE (20 * HZ)

static struct tty_driver *serial_driver;
static struct timer_list serial_timer;

static DEFINE_SPINLOCK(timer_lock);

int errno;

static int __simc (int a, int b, int c, int d, int e, int f)
{
      int ret;
      __asm__ __volatile__ ("simcall\n"
                  "mov %0, a2\n"
                  "mov %1, a3\n" : "=a" (ret), "=a" (errno)
                  : : "a2", "a3");
      return ret;
}

static char *serial_version = "0.1";
static char *serial_name = "ISS serial driver";

/*
 * 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 void rs_poll(unsigned long);

static int rs_open(struct tty_struct *tty, struct file * filp)
{
      int line = tty->index;

      if ((line < 0) || (line >= SERIAL_MAX_NUM_LINES))
            return -ENODEV;

      spin_lock(&timer_lock);

      if (tty->count == 1) {
            init_timer(&serial_timer);
            serial_timer.data = (unsigned long) tty;
            serial_timer.function = rs_poll;
            mod_timer(&serial_timer, jiffies + SERIAL_TIMER_VALUE);
      }
      spin_unlock(&timer_lock);

      return 0;
}


/*
 * ------------------------------------------------------------
 * iss_serial_close()
 *
 * This routine is called when the serial port gets closed.  First, we
 * wait for the last remaining data to be sent.  Then, we unlink its
 * async structure from the interrupt chain if necessary, and we free
 * that IRQ if nothing is left in the chain.
 * ------------------------------------------------------------
 */
static void rs_close(struct tty_struct *tty, struct file * filp)
{
      spin_lock(&timer_lock);
      if (tty->count == 1)
            del_timer_sync(&serial_timer);
      spin_unlock(&timer_lock);
}


static int rs_write(struct tty_struct * tty,
                const unsigned char *buf, int count)
{
      /* see drivers/char/serialX.c to reference original version */

      __simc (SYS_write, 1, (unsigned long)buf, count, 0, 0);
      return count;
}

static void rs_poll(unsigned long priv)
{
      struct tty_struct* tty = (struct tty_struct*) priv;

      struct timeval tv = { .tv_sec = 0, .tv_usec = 0 };
      int i = 0;
      unsigned char c;

      spin_lock(&timer_lock);

      while (__simc(SYS_select_one, 0, XTISS_SELECT_ONE_READ, (int)&tv,0,0)){
            __simc (SYS_read, 0, (unsigned long)&c, 1, 0, 0);
            tty_insert_flip_char(tty, c, TTY_NORMAL);
            i++;
      }

      if (i)
            tty_flip_buffer_push(tty);


      mod_timer(&serial_timer, jiffies + SERIAL_TIMER_VALUE);
      spin_unlock(&timer_lock);
}


static void rs_put_char(struct tty_struct *tty, unsigned char ch)
{
      char buf[2];

      if (!tty)
            return;

      buf[0] = ch;
      buf[1] = '\0';          /* Is this NULL necessary? */
      __simc (SYS_write, 1, (unsigned long) buf, 1, 0, 0);
}

static void rs_flush_chars(struct tty_struct *tty)
{
}

static int rs_write_room(struct tty_struct *tty)
{
      /* Let's say iss can always accept 2K characters.. */
      return 2 * 1024;
}

static int rs_chars_in_buffer(struct tty_struct *tty)
{
      /* the iss doesn't buffer characters */
      return 0;
}

static void rs_hangup(struct tty_struct *tty)
{
      /* Stub, once again.. */
}

static void rs_wait_until_sent(struct tty_struct *tty, int timeout)
{
      /* Stub, once again.. */
}

static int rs_read_proc(char *page, char **start, off_t off, int count,
                  int *eof, void *data)
{
      int len = 0;
      off_t begin = 0;

      len += sprintf(page, "serinfo:1.0 driver:%s\n", serial_version);
      *eof = 1;

      if (off >= len + begin)
            return 0;

      *start = page + (off - begin);
      return ((count < begin + len - off) ? count : begin + len - off);
}


static struct tty_operations serial_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,
      .hangup = rs_hangup,
      .wait_until_sent = rs_wait_until_sent,
      .read_proc = rs_read_proc
};

int __init rs_init(void)
{
      serial_driver = alloc_tty_driver(1);

      printk ("%s %s\n", serial_name, serial_version);

      /* Initialize the tty_driver structure */

      serial_driver->owner = THIS_MODULE;
      serial_driver->driver_name = "iss_serial";
      serial_driver->name = "ttyS";
      serial_driver->major = TTY_MAJOR;
      serial_driver->minor_start = 64;
      serial_driver->type = TTY_DRIVER_TYPE_SERIAL;
      serial_driver->subtype = SERIAL_TYPE_NORMAL;
      serial_driver->init_termios = tty_std_termios;
      serial_driver->init_termios.c_cflag =
            B9600 | CS8 | CREAD | HUPCL | CLOCAL;
      serial_driver->flags = TTY_DRIVER_REAL_RAW;

      tty_set_operations(serial_driver, &serial_ops);

      if (tty_register_driver(serial_driver))
            panic("Couldn't register serial driver\n");
      return 0;
}


static __exit void rs_exit(void)
{
      int error;

      if ((error = tty_unregister_driver(serial_driver)))
            printk("ISS_SERIAL: failed to unregister serial driver (%d)\n",
                   error);
      put_tty_driver(serial_driver);
}


/* We use `late_initcall' instead of just `__initcall' as a workaround for
 * the fact that (1) simcons_tty_init can't be called before tty_init,
 * (2) tty_init is called via `module_init', (3) if statically linked,
 * module_init == device_init, and (4) there's no ordering of init lists.
 * We can do this easily because simcons is always statically linked, but
 * other tty drivers that depend on tty_init and which must use
 * `module_init' to declare their init routines are likely to be broken.
 */

late_initcall(rs_init);


#ifdef CONFIG_SERIAL_CONSOLE

static void iss_console_write(struct console *co, const char *s, unsigned count)
{
      int len = strlen(s);

      if (s != 0 && *s != 0)
            __simc (SYS_write, 1, (unsigned long)s,
                  count < len ? count : len,0,0);
}

static struct tty_driver* iss_console_device(struct console *c, int *index)
{
      *index = c->index;
      return serial_driver;
}


static struct console sercons = {
      .name = "ttyS",
      .write = iss_console_write,
      .device = iss_console_device,
      .flags = CON_PRINTBUFFER,
      .index = -1
};

static int __init iss_console_init(void)
{
      register_console(&sercons);
      return 0;
}

console_initcall(iss_console_init);

#endif /* CONFIG_SERIAL_CONSOLE */


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