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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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