297 lines
6.1 KiB
C
297 lines
6.1 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* linux/arch/alpha/kernel/srmcons.c
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*
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* Callback based driver for SRM Console console device.
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* (TTY driver and console driver)
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*/
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/console.h>
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#include <linux/delay.h>
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#include <linux/mm.h>
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#include <linux/slab.h>
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#include <linux/spinlock.h>
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#include <linux/timer.h>
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#include <linux/tty.h>
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#include <linux/tty_driver.h>
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#include <linux/tty_flip.h>
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#include <asm/console.h>
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#include <linux/uaccess.h>
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static DEFINE_SPINLOCK(srmcons_callback_lock);
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static int srm_is_registered_console = 0;
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/*
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* The TTY driver
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*/
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#define MAX_SRM_CONSOLE_DEVICES 1 /* only support 1 console device */
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struct srmcons_private {
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struct tty_port port;
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struct timer_list timer;
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} srmcons_singleton;
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typedef union _srmcons_result {
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struct {
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unsigned long c :61;
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unsigned long status :3;
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} bits;
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long as_long;
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} srmcons_result;
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/* called with callback_lock held */
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static int
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srmcons_do_receive_chars(struct tty_port *port)
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{
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srmcons_result result;
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int count = 0, loops = 0;
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do {
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result.as_long = callback_getc(0);
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if (result.bits.status < 2) {
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tty_insert_flip_char(port, (char)result.bits.c, 0);
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count++;
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}
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} while((result.bits.status & 1) && (++loops < 10));
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if (count)
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tty_schedule_flip(port);
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return count;
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}
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static void
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srmcons_receive_chars(struct timer_list *t)
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{
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struct srmcons_private *srmconsp = from_timer(srmconsp, t, timer);
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struct tty_port *port = &srmconsp->port;
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unsigned long flags;
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int incr = 10;
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local_irq_save(flags);
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if (spin_trylock(&srmcons_callback_lock)) {
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if (!srmcons_do_receive_chars(port))
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incr = 100;
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spin_unlock(&srmcons_callback_lock);
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}
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spin_lock(&port->lock);
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if (port->tty)
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mod_timer(&srmconsp->timer, jiffies + incr);
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spin_unlock(&port->lock);
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local_irq_restore(flags);
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}
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/* called with callback_lock held */
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static int
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srmcons_do_write(struct tty_port *port, const char *buf, int count)
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{
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static char str_cr[1] = "\r";
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long c, remaining = count;
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srmcons_result result;
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char *cur;
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int need_cr;
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for (cur = (char *)buf; remaining > 0; ) {
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need_cr = 0;
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/*
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* Break it up into reasonable size chunks to allow a chance
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* for input to get in
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*/
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for (c = 0; c < min_t(long, 128L, remaining) && !need_cr; c++)
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if (cur[c] == '\n')
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need_cr = 1;
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while (c > 0) {
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result.as_long = callback_puts(0, cur, c);
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c -= result.bits.c;
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remaining -= result.bits.c;
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cur += result.bits.c;
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/*
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* Check for pending input iff a tty port was provided
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*/
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if (port)
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srmcons_do_receive_chars(port);
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}
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while (need_cr) {
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result.as_long = callback_puts(0, str_cr, 1);
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if (result.bits.c > 0)
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need_cr = 0;
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}
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}
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return count;
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}
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static int
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srmcons_write(struct tty_struct *tty,
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const unsigned char *buf, int count)
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{
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unsigned long flags;
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spin_lock_irqsave(&srmcons_callback_lock, flags);
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srmcons_do_write(tty->port, (const char *) buf, count);
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spin_unlock_irqrestore(&srmcons_callback_lock, flags);
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return count;
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}
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static int
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srmcons_write_room(struct tty_struct *tty)
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{
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return 512;
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}
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static int
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srmcons_chars_in_buffer(struct tty_struct *tty)
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{
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return 0;
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}
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static int
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srmcons_open(struct tty_struct *tty, struct file *filp)
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{
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struct srmcons_private *srmconsp = &srmcons_singleton;
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struct tty_port *port = &srmconsp->port;
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unsigned long flags;
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spin_lock_irqsave(&port->lock, flags);
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if (!port->tty) {
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tty->driver_data = srmconsp;
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tty->port = port;
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port->tty = tty; /* XXX proper refcounting */
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mod_timer(&srmconsp->timer, jiffies + 10);
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}
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spin_unlock_irqrestore(&port->lock, flags);
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return 0;
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}
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static void
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srmcons_close(struct tty_struct *tty, struct file *filp)
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{
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struct srmcons_private *srmconsp = tty->driver_data;
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struct tty_port *port = &srmconsp->port;
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unsigned long flags;
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spin_lock_irqsave(&port->lock, flags);
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if (tty->count == 1) {
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port->tty = NULL;
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del_timer(&srmconsp->timer);
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}
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spin_unlock_irqrestore(&port->lock, flags);
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}
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static struct tty_driver *srmcons_driver;
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static const struct tty_operations srmcons_ops = {
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.open = srmcons_open,
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.close = srmcons_close,
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.write = srmcons_write,
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.write_room = srmcons_write_room,
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.chars_in_buffer= srmcons_chars_in_buffer,
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};
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static int __init
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srmcons_init(void)
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{
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timer_setup(&srmcons_singleton.timer, srmcons_receive_chars, 0);
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if (srm_is_registered_console) {
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struct tty_driver *driver;
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int err;
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driver = alloc_tty_driver(MAX_SRM_CONSOLE_DEVICES);
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if (!driver)
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return -ENOMEM;
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tty_port_init(&srmcons_singleton.port);
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driver->driver_name = "srm";
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driver->name = "srm";
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driver->major = 0; /* dynamic */
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driver->minor_start = 0;
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driver->type = TTY_DRIVER_TYPE_SYSTEM;
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driver->subtype = SYSTEM_TYPE_SYSCONS;
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driver->init_termios = tty_std_termios;
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tty_set_operations(driver, &srmcons_ops);
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tty_port_link_device(&srmcons_singleton.port, driver, 0);
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err = tty_register_driver(driver);
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if (err) {
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put_tty_driver(driver);
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tty_port_destroy(&srmcons_singleton.port);
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return err;
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}
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srmcons_driver = driver;
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}
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return -ENODEV;
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}
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device_initcall(srmcons_init);
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/*
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* The console driver
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*/
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static void
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srm_console_write(struct console *co, const char *s, unsigned count)
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{
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unsigned long flags;
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spin_lock_irqsave(&srmcons_callback_lock, flags);
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srmcons_do_write(NULL, s, count);
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spin_unlock_irqrestore(&srmcons_callback_lock, flags);
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}
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static struct tty_driver *
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srm_console_device(struct console *co, int *index)
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{
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*index = co->index;
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return srmcons_driver;
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}
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static int
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srm_console_setup(struct console *co, char *options)
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{
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return 0;
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}
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static struct console srmcons = {
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.name = "srm",
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.write = srm_console_write,
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.device = srm_console_device,
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.setup = srm_console_setup,
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.flags = CON_PRINTBUFFER | CON_BOOT,
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.index = -1,
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};
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void __init
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register_srm_console(void)
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{
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if (!srm_is_registered_console) {
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callback_open_console();
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register_console(&srmcons);
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srm_is_registered_console = 1;
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}
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}
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void __init
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unregister_srm_console(void)
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{
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if (srm_is_registered_console) {
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callback_close_console();
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unregister_console(&srmcons);
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srm_is_registered_console = 0;
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}
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}
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