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 0d232589a923..e61346faf6a5 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;