drivers/accessibility/braille/braille_console.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * 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>
  */

 #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 bool 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 = vt_get_leds(fg_console, VC_CAPSLOCK);
 				break;
 			case KVAL(K_NUM):
 				on_off = vt_get_leds(fg_console, VC_NUMLOCK);
 				break;
 			case KVAL(K_HOLD):
 				on_off = vt_get_leds(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->flags & CON_BRL))
 		return 0;
 	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;
 	register_keyboard_notifier(&keyboard_notifier_block);
 	register_vt_notifier(&vt_notifier_block);
 	return 1;
 }

 int braille_unregister_console(struct console *console)
 {
 	if (braille_co != console)
 		return -EINVAL;
 	if (!(console->flags & CON_BRL))
 		return 0;
 	unregister_keyboard_notifier(&keyboard_notifier_block);
 	unregister_vt_notifier(&vt_notifier_block);
 	braille_co = NULL;
 	return 1;
 }
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	* 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>
	*/

	#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 bool 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 + 2WIDTH + 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 = vt_get_leds(fg_console, VC_CAPSLOCK);
	break;
	case KVAL(K_NUM):
	on_off = vt_get_leds(fg_console, VC_NUMLOCK);
	break;
	case KVAL(K_HOLD):
	on_off = vt_get_leds(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->flags & CON_BRL))
	return 0;
	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;
	register_keyboard_notifier(&keyboard_notifier_block);
	register_vt_notifier(&vt_notifier_block);
	return 1;
	}

	int braille_unregister_console(struct console *console)
	{
	if (braille_co != console)
	return -EINVAL;
	if (!(console->flags & CON_BRL))
	return 0;
	unregister_keyboard_notifier(&keyboard_notifier_block);
	unregister_vt_notifier(&vt_notifier_block);
	braille_co = NULL;
	return 1;
	}