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Basic braille screen reader support

Browse source 
This adds a minimalistic braille screen reader support.  This is meant to
be used by blind people e.g.  on boot failures or when / cannot be mounted
etc and thus the userland screen readers can not work.

[akpm@linux-foundation.org: fix exports]
Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Cc: Jiri Kosina <jikos@jikos.cz>
Cc: Dmitry Torokhov <dtor@mail.ru>
Acked-by: Alan Cox <alan@redhat.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Samuel Thibault 2008-04-30 00:54:51 -07:00 committed by Linus Torvalds
parent 730f412c08
commit f7511d5f66
15 changed files with 538 additions and 30 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

34
Documentation/braille-console.txt Normal file
View file

@ -0,0 +1,34 @@
Linux Braille Console
To get early boot messages on a braille device (before userspace screen
readers can start), you first need to compile the support for the usual serial
console (see serial-console.txt), and for braille device (in Device Drivers -
Accessibility).
Then you need to specify a console=brl, option on the kernel command line, the
format is:
console=brl,serial_options...
where serial_options... are the same as described in serial-console.txt
So for instance you can use console=brl,ttyS0 if the braille device is connected
to the first serial port, and console=brl,ttyS0,115200 to override the baud rate
to 115200, etc.
By default, the braille device will just show the last kernel message (console
mode). To review previous messages, press the Insert key to switch to the VT
review mode. In review mode, the arrow keys permit to browse in the VT content,
page up/down keys go at the top/bottom of the screen, and the home key goes back
to the cursor, hence providing very basic screen reviewing facility.
Sound feedback can be obtained by adding the braille_console.sound=1 kernel
parameter.
For simplicity, only one braille console can be enabled, other uses of
console=brl,... will be discarded. Also note that it does not interfere with
the console selection mecanism described in serial-console.txt
For now, only the VisioBraille device is supported.
Samuel Thibault <samuel.thibault@ens-lyon.org>

5
Documentation/kernel-parameters.txt
View file

@ -496,6 +496,11 @@ and is between 256 and 4096 characters. It is defined in the file
switching to the matching ttyS device later. The
options are the same as for ttyS, above.
If the device connected to the port is not a TTY but a braille
device, prepend "brl," before the device type, for instance
console=brl,ttyS0
For now, only VisioBraille is supported.
earlycon= [KNL] Output early console device and options.
uart[8250],io,<addr>[,options]
uart[8250],mmio,<addr>[,options]

3
arch/powerpc/kernel/ppc_ksyms.c
View file

@ -133,9 +133,6 @@ EXPORT_SYMBOL(adb_try_handler_change);
EXPORT_SYMBOL(cuda_request);
EXPORT_SYMBOL(cuda_poll);
#endif /* CONFIG_ADB_CUDA */
#ifdef CONFIG_VT
EXPORT_SYMBOL(kd_mksound);
#endif
EXPORT_SYMBOL(to_tm);
#ifdef CONFIG_PPC32

3
arch/ppc/kernel/ppc_ksyms.c
View file

@ -183,9 +183,6 @@ EXPORT_SYMBOL(cuda_poll);
#if defined(CONFIG_BOOTX_TEXT)
EXPORT_SYMBOL(btext_update_display);
#endif
#ifdef CONFIG_VT
EXPORT_SYMBOL(kd_mksound);
#endif
EXPORT_SYMBOL(to_tm);
EXPORT_SYMBOL(pm_power_off);

2
drivers/Kconfig
View file

@ -84,6 +84,8 @@ source "drivers/memstick/Kconfig"
source "drivers/leds/Kconfig"
source "drivers/accessibility/Kconfig"
source "drivers/infiniband/Kconfig"
source "drivers/edac/Kconfig"

1
drivers/Makefile
View file

@ -70,6 +70,7 @@ obj-$(CONFIG_WATCHDOG) += watchdog/
obj-$(CONFIG_PHONE) += telephony/
obj-$(CONFIG_MD) += md/
obj-$(CONFIG_BT) += bluetooth/
obj-$(CONFIG_ACCESSIBILITY) += accessibility/
obj-$(CONFIG_ISDN) += isdn/
obj-$(CONFIG_EDAC) += edac/
obj-$(CONFIG_MCA) += mca/

23
drivers/accessibility/Kconfig Normal file
View file

@ -0,0 +1,23 @@
menuconfig ACCESSIBILITY
bool "Accessibility support"
---help---
Enable a submenu where accessibility items may be enabled.
If unsure, say N.
if ACCESSIBILITY
config A11Y_BRAILLE_CONSOLE
bool "Console on braille device"
depends on VT
depends on SERIAL_CORE_CONSOLE
---help---
Enables console output on a braille device connected to a 8250
serial port. For now only the VisioBraille device is supported.
To actually enable it, you need to pass option
console=brl,ttyS0
to the kernel. Options are the same as for serial console.
If unsure, say N.
endif # ACCESSIBILITY

1
drivers/accessibility/Makefile Normal file
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@ -0,0 +1 @@
obj-y += braille/

1
drivers/accessibility/braille/Makefile Normal file
View file

@ -0,0 +1 @@
obj-$(CONFIG_A11Y_BRAILLE_CONSOLE) += braille_console.o

397
drivers/accessibility/braille/braille_console.c Normal file
View file

@ -0,0 +1,397 @@
/*
* Minimalistic braille device kernel support.
*
* By default, shows console messages on the braille device.
* Pressing Insert switches to VC browsing.
*
* Copyright (C) Samuel Thibault <samuel.thibault@ens-lyon.org>
*
* This program is free software ; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation ; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY ; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with the program ; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <linux/autoconf.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/console.h>
#include <linux/notifier.h>
#include <linux/selection.h>
#include <linux/vt_kern.h>
#include <linux/consolemap.h>
#include <linux/keyboard.h>
#include <linux/kbd_kern.h>
#include <linux/input.h>
MODULE_AUTHOR("samuel.thibault@ens-lyon.org");
MODULE_DESCRIPTION("braille device");
MODULE_LICENSE("GPL");
/*
* Braille device support part.
*/
/* Emit various sounds */
static int sound;
module_param(sound, bool, 0);
MODULE_PARM_DESC(sound, "emit sounds");
static void beep(unsigned int freq)
{
if (sound)
kd_mksound(freq, HZ/10);
}
/* mini console */
#define WIDTH 40
#define BRAILLE_KEY KEY_INSERT
static u16 console_buf[WIDTH];
static int console_cursor;
/* mini view of VC */
static int vc_x, vc_y, lastvc_x, lastvc_y;
/* show console ? (or show VC) */
static int console_show = 1;
/* pending newline ? */
static int console_newline = 1;
static int lastVC = -1;
static struct console *braille_co;
/* Very VisioBraille-specific */
static void braille_write(u16 *buf)
{
static u16 lastwrite[WIDTH];
unsigned char data[1 + 1 + 2*WIDTH + 2 + 1], csum = 0, *c;
u16 out;
int i;
if (!braille_co)
return;
if (!memcmp(lastwrite, buf, WIDTH * sizeof(*buf)))
return;
memcpy(lastwrite, buf, WIDTH * sizeof(*buf));
#define SOH 1
#define STX 2
#define ETX 2
#define EOT 4
#define ENQ 5
data[0] = STX;
data[1] = '>';
csum ^= '>';
c = &data[2];
for (i = 0; i < WIDTH; i++) {
out = buf[i];
if (out >= 0x100)
out = '?';
else if (out == 0x00)
out = ' ';
csum ^= out;
if (out <= 0x05) {
*c++ = SOH;
out |= 0x40;
}
*c++ = out;
}
if (csum <= 0x05) {
*c++ = SOH;
csum |= 0x40;
}
*c++ = csum;
*c++ = ETX;
braille_co->write(braille_co, data, c - data);
}
/* Follow the VC cursor*/
static void vc_follow_cursor(struct vc_data *vc)
{
vc_x = vc->vc_x - (vc->vc_x % WIDTH);
vc_y = vc->vc_y;
lastvc_x = vc->vc_x;
lastvc_y = vc->vc_y;
}
/* Maybe the VC cursor moved, if so follow it */
static void vc_maybe_cursor_moved(struct vc_data *vc)
{
if (vc->vc_x != lastvc_x || vc->vc_y != lastvc_y)
vc_follow_cursor(vc);
}
/* Show portion of VC at vc_x, vc_y */
static void vc_refresh(struct vc_data *vc)
{
u16 buf[WIDTH];
int i;
for (i = 0; i < WIDTH; i++) {
u16 glyph = screen_glyph(vc,
2 * (vc_x + i) + vc_y * vc->vc_size_row);
buf[i] = inverse_translate(vc, glyph, 1);
}
braille_write(buf);
}
/*
* Link to keyboard
*/
static int keyboard_notifier_call(struct notifier_block *blk,
unsigned long code, void *_param)
{
struct keyboard_notifier_param *param = _param;
struct vc_data *vc = param->vc;
int ret = NOTIFY_OK;
if (!param->down)
return ret;
switch (code) {
case KBD_KEYCODE:
if (console_show) {
if (param->value == BRAILLE_KEY) {
console_show = 0;
beep(880);
vc_maybe_cursor_moved(vc);
vc_refresh(vc);
ret = NOTIFY_STOP;
}
} else {
ret = NOTIFY_STOP;
switch (param->value) {
case KEY_INSERT:
beep(440);
console_show = 1;
lastVC = -1;
braille_write(console_buf);
break;
case KEY_LEFT:
if (vc_x > 0) {
vc_x -= WIDTH;
if (vc_x < 0)
vc_x = 0;
} else if (vc_y >= 1) {
beep(880);
vc_y--;
vc_x = vc->vc_cols-WIDTH;
} else
beep(220);
break;
case KEY_RIGHT:
if (vc_x + WIDTH < vc->vc_cols) {
vc_x += WIDTH;
} else if (vc_y + 1 < vc->vc_rows) {
beep(880);
vc_y++;
vc_x = 0;
} else
beep(220);
break;
case KEY_DOWN:
if (vc_y + 1 < vc->vc_rows)
vc_y++;
else
beep(220);
break;
case KEY_UP:
if (vc_y >= 1)
vc_y--;
else
beep(220);
break;
case KEY_HOME:
vc_follow_cursor(vc);
break;
case KEY_PAGEUP:
vc_x = 0;
vc_y = 0;
break;
case KEY_PAGEDOWN:
vc_x = 0;
vc_y = vc->vc_rows-1;
break;
default:
ret = NOTIFY_OK;
break;
}
if (ret == NOTIFY_STOP)
vc_refresh(vc);
}
break;
case KBD_POST_KEYSYM:
{
unsigned char type = KTYP(param->value) - 0xf0;
if (type == KT_SPEC) {
unsigned char val = KVAL(param->value);
int on_off = -1;
switch (val) {
case KVAL(K_CAPS):
on_off = vc_kbd_led(kbd_table + fg_console,
VC_CAPSLOCK);
break;
case KVAL(K_NUM):
on_off = vc_kbd_led(kbd_table + fg_console,
VC_NUMLOCK);
break;
case KVAL(K_HOLD):
on_off = vc_kbd_led(kbd_table + fg_console,
VC_SCROLLOCK);
break;
}
if (on_off == 1)
beep(880);
else if (on_off == 0)
beep(440);
}
}
case KBD_UNBOUND_KEYCODE:
case KBD_UNICODE:
case KBD_KEYSYM:
/* Unused */
break;
}
return ret;
}
static struct notifier_block keyboard_notifier_block = {
.notifier_call = keyboard_notifier_call,
};
static int vt_notifier_call(struct notifier_block *blk,
unsigned long code, void *_param)
{
struct vt_notifier_param *param = _param;
struct vc_data *vc = param->vc;
switch (code) {
case VT_ALLOCATE:
break;
case VT_DEALLOCATE:
break;
case VT_WRITE:
{
unsigned char c = param->c;
if (vc->vc_num != fg_console)
break;
switch (c) {
case '\b':
case 127:
if (console_cursor > 0) {
console_cursor--;
console_buf[console_cursor] = ' ';
}
break;
case '\n':
case '\v':
case '\f':
case '\r':
console_newline = 1;
break;
case '\t':
c = ' ';
/* Fallthrough */
default:
if (c < 32)
/* Ignore other control sequences */
break;
if (console_newline) {
memset(console_buf, 0, sizeof(console_buf));
console_cursor = 0;
console_newline = 0;
}
if (console_cursor == WIDTH)
memmove(console_buf, &console_buf[1],
(WIDTH-1) * sizeof(*console_buf));
else
console_cursor++;
console_buf[console_cursor-1] = c;
break;
}
if (console_show)
braille_write(console_buf);
else {
vc_maybe_cursor_moved(vc);
vc_refresh(vc);
}
break;
}
case VT_UPDATE:
/* Maybe a VT switch, flush */
if (console_show) {
if (vc->vc_num != lastVC) {
lastVC = vc->vc_num;
memset(console_buf, 0, sizeof(console_buf));
console_cursor = 0;
braille_write(console_buf);
}
} else {
vc_maybe_cursor_moved(vc);
vc_refresh(vc);
}
break;
}
return NOTIFY_OK;
}
static struct notifier_block vt_notifier_block = {
.notifier_call = vt_notifier_call,
};
/*
* Called from printk.c when console=brl is given
*/
int braille_register_console(struct console *console, int index,
char *console_options, char *braille_options)
{
int ret;
if (!console_options)
/* Only support VisioBraille for now */
console_options = "57600o8";
if (braille_co)
return -ENODEV;
if (console->setup) {
ret = console->setup(console, console_options);
if (ret != 0)
return ret;
}
console->flags |= CON_ENABLED;
console->index = index;
braille_co = console;
return 0;
}
int braille_unregister_console(struct console *console)
{
if (braille_co != console)
return -EINVAL;
braille_co = NULL;
return 0;
}
static int __init braille_init(void)
{
register_keyboard_notifier(&keyboard_notifier_block);
register_vt_notifier(&vt_notifier_block);
return 0;
}
console_initcall(braille_init);

1
drivers/char/consolemap.c
View file

@ -277,6 +277,7 @@ u16 inverse_translate(struct vc_data *conp, int glyph, int use_unicode)
return p->inverse_translations[m][glyph];
}
}
EXPORT_SYMBOL_GPL(inverse_translate);
static void update_user_maps(void)
{

2
drivers/char/keyboard.c
View file

@ -110,6 +110,7 @@ const int max_vals[] = {
const int NR_TYPES = ARRAY_SIZE(max_vals);
struct kbd_struct kbd_table[MAX_NR_CONSOLES];
EXPORT_SYMBOL_GPL(kbd_table);
static struct kbd_struct *kbd = kbd_table;
struct vt_spawn_console vt_spawn_con = {
@ -260,6 +261,7 @@ void kd_mksound(unsigned int hz, unsigned int ticks)
} else
kd_nosound(0);
}
EXPORT_SYMBOL(kd_mksound);
/*
* Setting the keyboard rate.

1
drivers/char/vt.c
View file

@ -4004,6 +4004,7 @@ u16 screen_glyph(struct vc_data *vc, int offset)
c |= 0x100;
return c;
}
EXPORT_SYMBOL_GPL(screen_glyph);
/* used by vcs - note the word offset */
unsigned short *screen_pos(struct vc_data *vc, int w_offset, int viewed)

4
include/linux/console.h
View file

@ -91,6 +91,7 @@ void give_up_console(const struct consw *sw);
#define CON_ENABLED (4)
#define CON_BOOT (8)
#define CON_ANYTIME (16) /* Safe to call when cpu is offline */
#define CON_BRL (32) /* Used for a braille device */
struct console {
char name[16];
@ -121,6 +122,9 @@ extern struct tty_driver *console_device(int *);
extern void console_stop(struct console *);
extern void console_start(struct console *);
extern int is_console_locked(void);
extern int braille_register_console(struct console *, int index,
char *console_options, char *braille_options);
extern int braille_unregister_console(struct console *);
extern int console_suspend_enabled;

90
kernel/printk.c
View file

@ -111,6 +111,9 @@ struct console_cmdline
char name[8]; /* Name of the driver */
int index; /* Minor dev. to use */
char *options; /* Options for the driver */
#ifdef CONFIG_A11Y_BRAILLE_CONSOLE
char *brl_options; /* Options for braille driver */
#endif
};
#define MAX_CMDLINECONSOLES 8
@ -808,15 +811,60 @@ static void call_console_drivers(unsigned start, unsigned end)
#endif
static int __add_preferred_console(char *name, int idx, char *options,
char *brl_options)
{
struct console_cmdline *c;
int i;
/*
* See if this tty is not yet registered, and
* if we have a slot free.
*/
for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++)
if (strcmp(console_cmdline[i].name, name) == 0 &&
console_cmdline[i].index == idx) {
if (!brl_options)
selected_console = i;
return 0;
}
if (i == MAX_CMDLINECONSOLES)
return -E2BIG;
if (!brl_options)
selected_console = i;
c = &console_cmdline[i];
strlcpy(c->name, name, sizeof(c->name));
c->options = options;
#ifdef CONFIG_A11Y_BRAILLE_CONSOLE
c->brl_options = brl_options;
#endif
c->index = idx;
return 0;
}
/*
* Set up a list of consoles. Called from init/main.c
*/
static int __init console_setup(char *str)
{
char buf[sizeof(console_cmdline[0].name) + 4]; /* 4 for index */
char *s, *options;
char *s, *options, *brl_options = NULL;
int idx;
#ifdef CONFIG_A11Y_BRAILLE_CONSOLE
if (!memcmp(str, "brl,", 4)) {
brl_options = "";
str += 4;
} else if (!memcmp(str, "brl=", 4)) {
brl_options = str + 4;
str = strchr(brl_options, ',');
if (!str) {
printk(KERN_ERR "need port name after brl=\n");
return 1;
}
*(str++) = 0;
}
#endif
/*
* Decode str into name, index, options.
*/
@ -841,7 +889,7 @@ static int __init console_setup(char *str)
idx = simple_strtoul(s, NULL, 10);
*s = 0;
add_preferred_console(buf, idx, options);
__add_preferred_console(buf, idx, options, brl_options);
return 1;
}
__setup("console=", console_setup);
@ -861,28 +909,7 @@ __setup("console=", console_setup);
*/
int add_preferred_console(char *name, int idx, char *options)
{
struct console_cmdline *c;
int i;
/*
* See if this tty is not yet registered, and
* if we have a slot free.
*/
for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0]; i++)
if (strcmp(console_cmdline[i].name, name) == 0 &&
console_cmdline[i].index == idx) {
selected_console = i;
return 0;
}
if (i == MAX_CMDLINECONSOLES)
return -E2BIG;
selected_console = i;
c = &console_cmdline[i];
memcpy(c->name, name, sizeof(c->name));
c->name[sizeof(c->name) - 1] = 0;
c->options = options;
c->index = idx;
return 0;
return __add_preferred_console(name, idx, options, NULL);
}
int update_console_cmdline(char *name, int idx, char *name_new, int idx_new, char *options)
@ -1163,6 +1190,16 @@ void register_console(struct console *console)
continue;
if (console->index < 0)
console->index = console_cmdline[i].index;
#ifdef CONFIG_A11Y_BRAILLE_CONSOLE
if (console_cmdline[i].brl_options) {
console->flags |= CON_BRL;
braille_register_console(console,
console_cmdline[i].index,
console_cmdline[i].options,
console_cmdline[i].brl_options);
return;
}
#endif
if (console->setup &&
console->setup(console, console_cmdline[i].options) != 0)
break;
@ -1221,6 +1258,11 @@ int unregister_console(struct console *console)
struct console *a, *b;
int res = 1;
#ifdef CONFIG_A11Y_BRAILLE_CONSOLE
if (console->flags & CON_BRL)
return braille_unregister_console(console);
#endif
acquire_console_sem();
if (console_drivers == console) {
console_drivers=console->next;