/*
* linux/arch/alpha/kernel/srmcons.c
*
* Callback based driver for SRM Console console device.
* (TTY driver and console driver)
*/
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/console.h>
#include <linux/delay.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/timer.h>
#include <linux/tty.h>
#include <linux/tty_driver.h>
#include <linux/tty_flip.h>
#include <asm/console.h>
#include <asm/uaccess.h>
static DEFINE_SPINLOCK(srmcons_callback_lock);
static int srm_is_registered_console = 0;
/*
* The TTY driver
*/
#define MAX_SRM_CONSOLE_DEVICES 1 /* only support 1 console device */
struct srmcons_private {
struct tty_struct *tty;
struct timer_list timer;
spinlock_t lock;
};
typedef union _srmcons_result {
struct {
unsigned long c :61;
unsigned long status :3;
} bits;
long as_long;
} srmcons_result;
/* called with callback_lock held */
static int
srmcons_do_receive_chars(struct tty_struct *tty)
{
srmcons_result result;
int count = 0, loops = 0;
do {
result.as_long = callback_getc(0);
if (result.bits.status < 2) {
tty_insert_flip_char(tty, (char)result.bits.c, 0);
count++;
}
} while((result.bits.status & 1) && (++loops < 10));
if (count)
tty_schedule_flip(tty);
return count;
}
static void
srmcons_receive_chars(unsigned long data)
{
struct srmcons_private *srmconsp = (struct srmcons_private *)data;
unsigned long flags;
int incr = 10;
local_irq_save(flags);
if (spin_trylock(&srmcons_callback_lock)) {
if (!srmcons_do_receive_chars(srmconsp->tty))
incr = 100;
spin_unlock(&srmcons_callback_lock);
}
spin_lock(&srmconsp->lock);
if (srmconsp->tty) {
srmconsp->timer.expires = jiffies + incr;
add_timer(&srmconsp->timer);
}
spin_unlock(&srmconsp->lock);
local_irq_restore(flags);
}
/* called with callback_lock held */
static int
srmcons_do_write(struct tty_struct *tty, const char *buf, int count)
{
static char str_cr[1] = "\r";
long c, remaining = count;
srmcons_result result;
char *cur;
int need_cr;
for (cur = (char *)buf; remaining > 0; ) {
need_cr = 0;
/*
* Break it up into reasonable size chunks to allow a chance
* for input to get in
*/
for (c = 0; c < min_t(long, 128L, remaining) && !need_cr; c++)
if (cur[c] == '\n')
need_cr = 1;
while (c > 0) {
result.as_long = callback_puts(0, cur, c);
c -= result.bits.c;
remaining -= result.bits.c;
cur += result.bits.c;
/*
* Check for pending input iff a tty was provided
*/
if (tty)
srmcons_do_receive_chars(tty);
}
while (need_cr) {
result.as_long = callback_puts(0, str_cr, 1);
if (result.bits.c > 0)
need_cr = 0;
}
}
return count;
}
static int
srmcons_write(struct tty_struct *tty,
const unsigned char *buf, int count)
{
unsigned long flags;
spin_lock_irqsave(&srmcons_callback_lock, flags);
srmcons_do_write(tty, (const char *) buf, count);
spin_unlock_irqrestore(&srmcons_callback_lock, flags);
return count;
}
static int
srmcons_write_room(struct tty_struct *tty)
{
return 512;
}
static int
srmcons_chars_in_buffer(struct tty_struct *tty)
{
return 0;
}
static int
srmcons_get_private_struct(struct srmcons_private **ps)
{
static struct srmcons_private *srmconsp = NULL;
static DEFINE_SPINLOCK(srmconsp_lock);
unsigned long flags;
int retval = 0;
if (srmconsp == NULL) {
spin_lock_irqsave(&srmconsp_lock, flags);
srmconsp = kmalloc(sizeof(*srmconsp), GFP_KERNEL);
if (srmconsp == NULL)
retval = -ENOMEM;
else {
srmconsp->tty = NULL;
spin_lock_init(&srmconsp->lock);
init_timer(&srmconsp->timer);
}
spin_unlock_irqrestore(&srmconsp_lock, flags);
}
*ps = srmconsp;
return retval;
}
static int
srmcons_open(struct tty_struct *tty, struct file *filp)
{
struct srmcons_private *srmconsp;
unsigned long flags;
int retval;
retval = srmcons_get_private_struct(&srmconsp);
if (retval)
return retval;
spin_lock_irqsave(&srmconsp->lock, flags);
if (!srmconsp->tty) {
tty->driver_data = srmconsp;
srmconsp->tty = tty;
srmconsp->timer.function = srmcons_receive_chars;
srmconsp->timer.data = (unsigned long)srmconsp;
srmconsp->timer.expires = jiffies + 10;
add_timer(&srmconsp->timer);
}
spin_unlock_irqrestore(&srmconsp->lock, flags);
return 0;
}
static void
srmcons_close(struct tty_struct *tty, struct file *filp)
{
struct srmcons_private *srmconsp = tty->driver_data;
unsigned long flags;
spin_lock_irqsave(&srmconsp->lock, flags);
if (tty->count == 1) {
srmconsp->tty = NULL;
del_timer(&srmconsp->timer);
}
spin_unlock_irqrestore(&srmconsp->lock, flags);
}
static struct tty_driver *srmcons_driver;
static struct tty_operations srmcons_ops = {
.open = srmcons_open,
.close = srmcons_close,
.write = srmcons_write,
.write_room = srmcons_write_room,
.chars_in_buffer= srmcons_chars_in_buffer,
};
static int __init
srmcons_init(void)
{
if (srm_is_registered_console) {
struct tty_driver *driver;
int err;
driver = alloc_tty_driver(MAX_SRM_CONSOLE_DEVICES);
if (!driver)
return -ENOMEM;
driver->driver_name = "srm";
driver->name = "srm";
driver->major = 0; /* dynamic */
driver->minor_start = 0;
driver->type = TTY_DRIVER_TYPE_SYSTEM;
driver->subtype = SYSTEM_TYPE_SYSCONS;
driver->init_termios = tty_std_termios;
tty_set_operations(driver, &srmcons_ops);
err = tty_register_driver(driver);
if (err) {
put_tty_driver(driver);
return err;
}
srmcons_driver = driver;
}
return -ENODEV;
}
module_init(srmcons_init);
/*
* The console driver
*/
static void
srm_console_write(struct console *co, const char *s, unsigned count)
{
unsigned long flags;
spin_lock_irqsave(&srmcons_callback_lock, flags);
srmcons_do_write(NULL, s, count);
spin_unlock_irqrestore(&srmcons_callback_lock, flags);
}
static struct tty_driver *
srm_console_device(struct console *co, int *index)
{
*index = co->index;
return srmcons_driver;
}
static int __init
srm_console_setup(struct console *co, char *options)
{
return 0;
}
static struct console srmcons = {
.name = "srm",
.write = srm_console_write,
.device = srm_console_device,
.setup = srm_console_setup,
.flags = CON_PRINTBUFFER,
.index = -1,
};
void __init
register_srm_console(void)
{
if (!srm_is_registered_console) {
callback_open_console();
register_console(&srmcons);
srm_is_registered_console = 1;
}
}
void __init
unregister_srm_console(void)
{
if (srm_is_registered_console) {
callback_close_console();
unregister_console(&srmcons);
srm_is_registered_console = 0;
}
}
