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/*
* arch/v850/kernel/memcons.c -- Console I/O to a memory buffer
*
* Copyright (C) 2001,02 NEC Corporation
* Copyright (C) 2001,02 Miles Bader <miles@gnu.org>
*
* 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.
*
* Written by Miles Bader <miles@gnu.org>
*/
#include <linux/kernel.h>
#include <linux/console.h>
#include <linux/tty.h>
#include <linux/tty_driver.h>
#include <linux/init.h>
/* If this device is enabled, the linker map should define start and
end points for its buffer. */
extern char memcons_output[], memcons_output_end;
/* Current offset into the buffer. */
static unsigned long memcons_offs = 0;
/* Spinlock protecting memcons_offs. */
static DEFINE_SPINLOCK(memcons_lock);
static size_t write (const char *buf, size_t len)
{
unsigned long flags;
char *point;
spin_lock_irqsave (memcons_lock, flags);
point = memcons_output + memcons_offs;
if (point + len >= &memcons_output_end) {
len = &memcons_output_end - point;
memcons_offs = 0;
} else
memcons_offs += len;
spin_unlock_irqrestore (memcons_lock, flags);
memcpy (point, buf, len);
return len;
}
/* Low-level console. */
static void memcons_write (struct console *co, const char *buf, unsigned len)
{
while (len > 0)
len -= write (buf, len);
}
static struct tty_driver *tty_driver;
static struct tty_driver *memcons_device (struct console *co, int *index)
{
*index = co->index;
return tty_driver;
}
static struct console memcons =
{
.name = "memcons",
.write = memcons_write,
.device = memcons_device,
.flags = CON_PRINTBUFFER,
.index = -1,
};
void memcons_setup (void)
{
register_console (&memcons);
printk (KERN_INFO "Console: static memory buffer (memcons)\n");
}
/* Higher level TTY interface. */
int memcons_tty_open (struct tty_struct *tty, struct file *filp)
{
return 0;
}
int memcons_tty_write (struct tty_struct *tty, const unsigned char *buf, int len)
{
return write (buf, len);
}
int memcons_tty_write_room (struct tty_struct *tty)
{
return &memcons_output_end - (memcons_output + memcons_offs);
}
int memcons_tty_chars_in_buffer (struct tty_struct *tty)
{
/* We have no buffer. */
return 0;
}
static struct tty_operations ops = {
.open = memcons_tty_open,
.write = memcons_tty_write,
.write_room = memcons_tty_write_room,
.chars_in_buffer = memcons_tty_chars_in_buffer,
};
int __init memcons_tty_init (void)
{
int err;
struct tty_driver *driver = alloc_tty_driver(1);
if (!driver)
return -ENOMEM;
driver->name = "memcons";
driver->major = TTY_MAJOR;
driver->minor_start = 64;
driver->type = TTY_DRIVER_TYPE_SYSCONS;
driver->init_termios = tty_std_termios;
tty_set_operations(driver, &ops);
err = tty_register_driver(driver);
if (err) {
put_tty_driver(driver);
return err;
}
tty_driver = driver;
return 0;
}
__initcall (memcons_tty_init);
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