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-rw-r--r--arch/v850/kernel/memcons.c135
1 files changed, 135 insertions, 0 deletions
diff --git a/arch/v850/kernel/memcons.c b/arch/v850/kernel/memcons.c
new file mode 100644
index 000000000000..491614c435cd
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+++ b/arch/v850/kernel/memcons.c
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1/*
2 * arch/v850/kernel/memcons.c -- Console I/O to a memory buffer
3 *
4 * Copyright (C) 2001,02 NEC Corporation
5 * Copyright (C) 2001,02 Miles Bader <miles@gnu.org>
6 *
7 * This file is subject to the terms and conditions of the GNU General
8 * Public License. See the file COPYING in the main directory of this
9 * archive for more details.
10 *
11 * Written by Miles Bader <miles@gnu.org>
12 */
13
14#include <linux/kernel.h>
15#include <linux/console.h>
16#include <linux/tty.h>
17#include <linux/tty_driver.h>
18#include <linux/init.h>
19
20/* If this device is enabled, the linker map should define start and
21 end points for its buffer. */
22extern char memcons_output[], memcons_output_end;
23
24/* Current offset into the buffer. */
25static unsigned long memcons_offs = 0;
26
27/* Spinlock protecting memcons_offs. */
28static DEFINE_SPINLOCK(memcons_lock);
29
30
31static size_t write (const char *buf, size_t len)
32{
33 int flags;
34 char *point;
35
36 spin_lock_irqsave (memcons_lock, flags);
37
38 point = memcons_output + memcons_offs;
39 if (point + len >= &memcons_output_end) {
40 len = &memcons_output_end - point;
41 memcons_offs = 0;
42 } else
43 memcons_offs += len;
44
45 spin_unlock_irqrestore (memcons_lock, flags);
46
47 memcpy (point, buf, len);
48
49 return len;
50}
51
52
53/* Low-level console. */
54
55static void memcons_write (struct console *co, const char *buf, unsigned len)
56{
57 while (len > 0)
58 len -= write (buf, len);
59}
60
61static struct tty_driver *tty_driver;
62
63static struct tty_driver *memcons_device (struct console *co, int *index)
64{
65 *index = co->index;
66 return tty_driver;
67}
68
69static struct console memcons =
70{
71 .name = "memcons",
72 .write = memcons_write,
73 .device = memcons_device,
74 .flags = CON_PRINTBUFFER,
75 .index = -1,
76};
77
78void memcons_setup (void)
79{
80 register_console (&memcons);
81 printk (KERN_INFO "Console: static memory buffer (memcons)\n");
82}
83
84/* Higher level TTY interface. */
85
86int memcons_tty_open (struct tty_struct *tty, struct file *filp)
87{
88 return 0;
89}
90
91int memcons_tty_write (struct tty_struct *tty, const unsigned char *buf, int len)
92{
93 return write (buf, len);
94}
95
96int memcons_tty_write_room (struct tty_struct *tty)
97{
98 return &memcons_output_end - (memcons_output + memcons_offs);
99}
100
101int memcons_tty_chars_in_buffer (struct tty_struct *tty)
102{
103 /* We have no buffer. */
104 return 0;
105}
106
107static struct tty_operations ops = {
108 .open = memcons_tty_open,
109 .write = memcons_tty_write,
110 .write_room = memcons_tty_write_room,
111 .chars_in_buffer = memcons_tty_chars_in_buffer,
112};
113
114int __init memcons_tty_init (void)
115{
116 int err;
117 struct tty_driver *driver = alloc_tty_driver(1);
118 if (!driver)
119 return -ENOMEM;
120
121 driver->name = "memcons";
122 driver->major = TTY_MAJOR;
123 driver->minor_start = 64;
124 driver->type = TTY_DRIVER_TYPE_SYSCONS;
125 driver->init_termios = tty_std_termios;
126 tty_set_operations(driver, &ops);
127 err = tty_register_driver(driver);
128 if (err) {
129 put_tty_driver(driver);
130 return err;
131 }
132 tty_driver = driver;
133 return 0;
134}
135__initcall (memcons_tty_init);