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