aboutsummaryrefslogtreecommitdiff
path: root/arch/v850/kernel/memcons.c
blob: 92f514fdcc79fa608e98093e1d003d506ef0eaf1 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
/*
 * 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 const 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);