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Subject[PATCH] Basic braille screen reader support
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.

Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org

--- linux-2.6.24-orig/drivers/char/consolemap.c 2008-01-25 08:32:05.000000000 +0000
+++ linux-2.6.24-perso/drivers/char/consolemap.c 2008-02-03 21:27:04.000000000 +0000
@@ -277,6 +277,7 @@
return p->inverse_translations[m][glyph];
}
}
+EXPORT_SYMBOL_GPL(inverse_translate);

static void update_user_maps(void)
{
--- linux-2.6.24-orig/drivers/char/vt.c 2008-01-25 08:32:06.000000000 +0000
+++ linux-2.6.24-perso/drivers/char/vt.c 2008-02-03 21:27:04.000000000 +0000
@@ -3982,6 +3982,7 @@
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)
--- linux-2.6.24-orig/drivers/char/keyboard.c 2008-01-25 08:32:06.000000000 +0000
+++ linux-2.6.24-perso/drivers/char/keyboard.c 2008-02-04 02:44:37.000000000 +0000
@@ -110,6 +110,7 @@
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 @@
} else
kd_nosound(0);
}
+EXPORT_SYMBOL_GPL(kd_mksound);

/*
* Setting the keyboard rate.
--- linux-2.6.24-orig/drivers/Kconfig 2008-01-25 08:32:04.000000000 +0000
+++ linux-2.6.24-perso/drivers/Kconfig 2008-02-04 01:32:17.000000000 +0000
@@ -95,4 +95,6 @@
source "drivers/uio/Kconfig"

source "drivers/virtio/Kconfig"
+
+source "drivers/a11y/Kconfig"
endmenu
--- linux-2.6.24-orig/drivers/Makefile 2008-01-25 08:32:04.000000000 +0000
+++ linux-2.6.24-perso/drivers/Makefile 2008-02-04 01:33:27.000000000 +0000
@@ -28,6 +28,8 @@
obj-$(CONFIG_FB_INTEL) += video/intelfb/

obj-y += serial/
+# a11y comes after serial because it depends on it
+obj-$(CONFIG_A11Y) += a11y/
obj-$(CONFIG_PARPORT) += parport/
obj-y += base/ block/ misc/ mfd/ net/ media/
obj-$(CONFIG_NUBUS) += nubus/
--- linux-2.6.24-orig/include/linux/serial_8250.h 2007-10-09 21:31:38.000000000 +0100
+++ linux-2.6.24-perso/include/linux/serial_8250.h 2008-02-03 21:28:40.000000000 +0000
@@ -66,4 +66,6 @@
extern int serial8250_find_port_for_earlycon(void);
extern int setup_early_serial8250_console(char *cmdline);

+extern struct console serial8250_console;
+
#endif
--- linux-2.6.24-orig/drivers/serial/8250.c 2007-10-09 21:31:38.000000000 +0100
+++ linux-2.6.24-perso/drivers/serial/8250.c 2008-02-03 21:29:54.000000000 +0000
@@ -2547,7 +2547,7 @@
}

static struct uart_driver serial8250_reg;
-static struct console serial8250_console = {
+struct console serial8250_console = {
.name = "ttyS",
.write = serial8250_console_write,
.device = uart_console_device,
@@ -2557,6 +2557,7 @@
.index = -1,
.data = &serial8250_reg,
};
+EXPORT_SYMBOL_GPL(serial8250_console);

static int __init serial8250_console_init(void)
{
diff -urN linux-2.6.24-orig/drivers/a11y/braille/braille_console.c linux-2.6.24-perso/drivers/a11y/braille/braille_console.c
--- linux-2.6.24-orig/drivers/a11y/braille/braille_console.c 1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.24-perso/drivers/a11y/braille/braille_console.c 2008-02-04 01:58:16.000000000 +0000
@@ -0,0 +1,390 @@
+/*
+ * 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>
+
+#include <linux/serial_8250.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");
+#define beep(freq) do { if (sound) kd_mksound(freq, HZ/10); } while(0)
+
+/* mini console */
+#define WIDTH 40
+#define BRAILLE_KEY KEY_INSERT
+static u16 console_buf[WIDTH];
+static int console_cursor = 0;
+
+/* 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;
+
+ serial8250_console.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;
+ 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,
+};
+
+/*
+ * Link to serial console
+ */
+
+static int __init braille_console_setup(struct console *co, char *options)
+{
+ int ret = 0;
+ if (co->index == -1)
+ co->index = 0;
+#ifndef MODULE
+ ret = serial8250_console.setup(co, options);
+ if (ret < 0)
+ return ret;
+#endif
+ braille_co = co;
+ return ret;
+}
+
+static struct console braille_console = {
+ .name = "brl",
+ .setup = braille_console_setup,
+ .flags = CON_PRINTBUFFER,
+ .index = -1,
+};
+
+/*
+ * Module access
+ */
+
+static int __init checkinit(void)
+{
+ register_console(&braille_console);
+ register_keyboard_notifier(&keyboard_notifier_block);
+ register_vt_notifier(&vt_notifier_block);
+ return 0;
+}
+static void __exit checkexit(void)
+{
+ unregister_vt_notifier(&vt_notifier_block);
+ unregister_keyboard_notifier(&keyboard_notifier_block);
+ unregister_console(&braille_console);
+}
+
+module_init(checkinit);
+module_exit(checkexit);
diff -urN linux-2.6.24-orig/drivers/a11y/Kconfig linux-2.6.24-perso/drivers/a11y/Kconfig
--- linux-2.6.24-orig/drivers/a11y/Kconfig 1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.24-perso/drivers/a11y/Kconfig 2008-02-04 01:54:36.000000000 +0000
@@ -0,0 +1,22 @@
+menuconfig A11Y
+ bool "Accessibility support"
+ ---help---
+ Enable a submenu where accessibility items may be enabled.
+
+ If unsure, say N.
+
+if A11Y
+config A11Y_BRAILLE_CONSOLE
+ tristate "Console on braille device"
+ depends on SERIAL_8250_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=brl0
+ to the kernel. Options are the same as for serial console.
+
+ If unsure, say N.
+
+endif # A11Y
diff -urN linux-2.6.24-orig/drivers/a11y/Makefile linux-2.6.24-perso/drivers/a11y/Makefile
--- linux-2.6.24-orig/drivers/a11y/Makefile 1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.24-perso/drivers/a11y/Makefile 2008-02-04 01:42:32.000000000 +0000
@@ -0,0 +1 @@
+obj-$(CONFIG_A11Y_BRAILLE_CONSOLE) += braille/braille_console.o

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