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.

[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>

1 files changed, 66 insertions, 24 deletions

diff --git a/kernel/printk.c b/kernel/printk.c
index 0d23258..e61346f 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -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;