2 files changed, 437 insertions, 34 deletions

diff --git a/drivers/char/vt.c b/drivers/char/vt.c
index d7ff7fdb6fe3..d788a0eaf26a 100644
--- a/drivers/char/vt.c
+++ b/drivers/char/vt.c
@@ -98,9 +98,21 @@
 #include <asm/system.h>
 #include <asm/uaccess.h>
 
+#define MAX_NR_CON_DRIVER 16
 
+#define CON_DRIVER_FLAG_BIND 1
+#define CON_DRIVER_FLAG_INIT 2
+
+struct con_driver {
+        const struct consw *con;
+        const char *desc;
+        int first;
+        int last;
+        int flag;
+};
+
+static struct con_driver registered_con_driver[MAX_NR_CON_DRIVER];
 const struct consw *conswitchp;
-static struct consw *defcsw; /* default console */
 
 /* A bitmap for codes <32. A bit of 1 indicates that the code
  * corresponding to that bit number invokes some special action
@@ -2558,7 +2570,7 @@ static int __init con_init(void)
 {
         const char *display_desc = NULL;
         struct vc_data *vc;
-        unsigned int currcons = 0;
+        unsigned int currcons = 0, i;
 
         acquire_console_sem();
 
@@ -2570,6 +2582,22 @@ static int __init con_init(void)
                 return 0;
         }
 
+        for (i = 0; i < MAX_NR_CON_DRIVER; i++) {
+                struct con_driver *con_driver = &registered_con_driver[i];
+
+                if (con_driver->con == NULL) {
+                        con_driver->con = conswitchp;
+                        con_driver->desc = display_desc;
+                        con_driver->flag = CON_DRIVER_FLAG_INIT;
+                        con_driver->first = 0;
+                        con_driver->last = MAX_NR_CONSOLES - 1;
+                        break;
+                }
+        }
+
+        for (i = 0; i < MAX_NR_CONSOLES; i++)
+                con_driver_map[i] = conswitchp;
+
         init_timer(&console_timer);
         console_timer.function = blank_screen_t;
         if (blankinterval) {
@@ -2658,33 +2686,36 @@ int __init vty_init(void)
 
 #ifndef VT_SINGLE_DRIVER
 
-/*
- *      If we support more console drivers, this function is used
- *      when a driver wants to take over some existing consoles
- *      and become default driver for newly opened ones.
- */
-
-int take_over_console(const struct consw *csw, int first, int last, int deflt)
+static int bind_con_driver(const struct consw *csw, int first, int last,
+                           int deflt)
 {
-        int i, j = -1, k = -1;
-        const char *desc;
-        struct module *owner;
+        struct module *owner = csw->owner;
+        const char *desc = NULL;
+        struct con_driver *con_driver;
+        int i, j = -1, k = -1, retval = -ENODEV;
 
-        owner = csw->owner;
         if (!try_module_get(owner))
                 return -ENODEV;
 
-        /* save default console, for possible recovery later on */
-        if (!defcsw)
-                defcsw = (struct consw *) conswitchp;
-
         acquire_console_sem();
-        desc = csw->con_startup();
 
-        if (!desc) {
-                release_console_sem();
-                module_put(owner);
-                return -ENODEV;
+        /* check if driver is registered */
+        for (i = 0; i < MAX_NR_CON_DRIVER; i++) {
+                con_driver = &registered_con_driver[i];
+
+                if (con_driver->con == csw) {
+                        desc = con_driver->desc;
+                        retval = 0;
+                        break;
+                }
+        }
+
+        if (retval)
+                goto err;
+
+        if (!(con_driver->flag & CON_DRIVER_FLAG_INIT)) {
+                csw->con_startup();
+                con_driver->flag |= CON_DRIVER_FLAG_INIT;
         }
 
         if (deflt) {
@@ -2695,6 +2726,9 @@ int take_over_console(const struct consw *csw, int first, int last, int deflt)
                 conswitchp = csw;
         }
 
+        first = max(first, con_driver->first);
+        last = min(last, con_driver->last);
+
         for (i = first; i <= last; i++) {
                 int old_was_color;
                 struct vc_data *vc = vc_cons[i].d;
@@ -2746,33 +2780,400 @@ int take_over_console(const struct consw *csw, int first, int last, int deflt)
         } else
                 printk("to %s\n", desc);
 
+        retval = 0;
+err:
         release_console_sem();
         module_put(owner);
-        return 0;
-}
+        return retval;
+};
 
-void give_up_console(const struct consw *csw)
+static int unbind_con_driver(const struct consw *csw, int first, int last,
+                             int deflt)
 {
-        int i, first = -1, last = -1, deflt = 0;
+        struct module *owner = csw->owner;
+        const struct consw *defcsw = NULL;
+        struct con_driver *con_driver = NULL, *con_back = NULL;
+        int i, retval = -ENODEV;
 
-        for (i = 0; i < MAX_NR_CONSOLES; i++)
+        if (!try_module_get(owner))
+                return -ENODEV;
+
+        acquire_console_sem();
+
+        /* check if driver is registered and if it is unbindable */
+        for (i = 0; i < MAX_NR_CON_DRIVER; i++) {
+                con_driver = &registered_con_driver[i];
+
+                if (con_driver->con == csw &&
+                    con_driver->flag & CON_DRIVER_FLAG_BIND) {
+                        retval = 0;
+                        break;
+                }
+        }
+
+        if (retval) {
+                release_console_sem();
+                goto err;
+        }
+
+        /* check if backup driver exists */
+        for (i = 0; i < MAX_NR_CON_DRIVER; i++) {
+                con_back = &registered_con_driver[i];
+
+                if (con_back->con &&
+                    !(con_back->flag & CON_DRIVER_FLAG_BIND)) {
+                        defcsw = con_back->con;
+                        retval = 0;
+                        break;
+                }
+        }
+
+        if (retval) {
+                release_console_sem();
+                goto err;
+        }
+
+        if (!con_is_bound(csw)) {
+                release_console_sem();
+                goto err;
+        }
+
+        first = max(first, con_driver->first);
+        last = min(last, con_driver->last);
+
+        for (i = first; i <= last; i++) {
                 if (con_driver_map[i] == csw) {
-                        if (first == -1)
-                                first = i;
-                        last = i;
                         module_put(csw->owner);
                         con_driver_map[i] = NULL;
                 }
+        }
+
+        if (!con_is_bound(defcsw)) {
+                defcsw->con_startup();
+                con_back->flag |= CON_DRIVER_FLAG_INIT;
+        }
+
+        if (!con_is_bound(csw))
+                con_driver->flag &= ~CON_DRIVER_FLAG_INIT;
+
+        release_console_sem();
+        retval = bind_con_driver(defcsw, first, last, deflt);
+err:
+        module_put(owner);
+        return retval;
+
+}
+
+/**
+ * con_is_bound - checks if driver is bound to the console
+ * @csw: console driver
+ *
+ * RETURNS: zero if unbound, nonzero if bound
+ *
+ * Drivers can call this and if zero, they should release
+ * all resources allocated on con_startup()
+ */
+int con_is_bound(const struct consw *csw)
+{
+        int i, bound = 0;
+
+        for (i = 0; i < MAX_NR_CONSOLES; i++) {
+                if (con_driver_map[i] == csw) {
+                        bound = 1;
+                        break;
+                }
+        }
+
+        return bound;
+}
+EXPORT_SYMBOL(con_is_bound);
+
+/**
+ * register_con_driver - register console driver to console layer
+ * @csw: console driver
+ * @first: the first console to take over, minimum value is 0
+ * @last: the last console to take over, maximum value is MAX_NR_CONSOLES -1
+ *
+ * DESCRIPTION: This function registers a console driver which can later
+ * bind to a range of consoles specified by @first and @last. It will
+ * also initialize the console driver by calling con_startup().
+ */
+int register_con_driver(const struct consw *csw, int first, int last)
+{
+        struct module *owner = csw->owner;
+        struct con_driver *con_driver;
+        const char *desc;
+        int i, retval = 0;
+
+        if (!try_module_get(owner))
+                return -ENODEV;
+
+        acquire_console_sem();
+
+        for (i = 0; i < MAX_NR_CON_DRIVER; i++) {
+                con_driver = &registered_con_driver[i];
+
+                /* already registered */
+                if (con_driver->con == csw)
+                        retval = -EINVAL;
+        }
+
+        if (retval)
+                goto err;
+
+        desc = csw->con_startup();
+
+        if (!desc)
+                goto err;
+
+        retval = -EINVAL;
+
+        for (i = 0; i < MAX_NR_CON_DRIVER; i++) {
+                con_driver = &registered_con_driver[i];
+
+                if (con_driver->con == NULL) {
+                        con_driver->con = csw;
+                        con_driver->desc = desc;
+                        con_driver->flag = CON_DRIVER_FLAG_BIND |
+                                           CON_DRIVER_FLAG_INIT;
+                        con_driver->first = first;
+                        con_driver->last = last;
+                        retval = 0;
+                        break;
+                }
+        }
+
+err:
+        release_console_sem();
+        module_put(owner);
+        return retval;
+}
+EXPORT_SYMBOL(register_con_driver);
+
+/**
+ * unregister_con_driver - unregister console driver from console layer
+ * @csw: console driver
+ *
+ * DESCRIPTION: All drivers that registers to the console layer must
+ * call this function upon exit, or if the console driver is in a state
+ * where it won't be able to handle console services, such as the
+ * framebuffer console without loaded framebuffer drivers.
+ *
+ * The driver must unbind first prior to unregistration.
+ */
+int unregister_con_driver(const struct consw *csw)
+{
+        int i, retval = -ENODEV;
+
+        acquire_console_sem();
+
+        /* cannot unregister a bound driver */
+        if (con_is_bound(csw))
+                goto err;
+
+        for (i = 0; i < MAX_NR_CON_DRIVER; i++) {
+                struct con_driver *con_driver = &registered_con_driver[i];
+
+                if (con_driver->con == csw &&
+                    con_driver->flag & CON_DRIVER_FLAG_BIND) {
+                        con_driver->con = NULL;
+                        con_driver->desc = NULL;
+                        con_driver->flag = 0;
+                        con_driver->first = 0;
+                        con_driver->last = 0;
+                        retval = 0;
+                        break;
+                }
+        }
+
+err:
+        release_console_sem();
+        return retval;
+}
+EXPORT_SYMBOL(unregister_con_driver);
+
+/*
+ *      If we support more console drivers, this function is used
+ *      when a driver wants to take over some existing consoles
+ *      and become default driver for newly opened ones.
+ *
+ *      take_over_console is basically a register followed by unbind
+ */
+int take_over_console(const struct consw *csw, int first, int last, int deflt)
+{
+        int err;
+
+        err = register_con_driver(csw, first, last);
+
+        if (!err)
+                err = bind_con_driver(csw, first, last, deflt);
+
+        return err;
+}
+
+/*
+ * give_up_console is a wrapper to unregister_con_driver. It will only
+ * work if driver is fully unbound.
+ */
+void give_up_console(const struct consw *csw)
+{
+        unregister_con_driver(csw);
+}
+
+/*
+ * this function is intended to be called by the tty layer only
+ */
+int vt_bind(int index)
+{
+        const struct consw *defcsw = NULL, *csw = NULL;
+        struct con_driver *con;
+        int i, more = 1, first = -1, last = -1, deflt = 0;
+
+        if (index >= MAX_NR_CON_DRIVER)
+                goto err;
+
+        con = &registered_con_driver[index];
+
+        if (!con->con || !(con->flag & CON_DRIVER_FLAG_BIND))
+                goto err;
+
+        csw = con->con;
+
+        for (i = 0; i < MAX_NR_CON_DRIVER; i++) {
+                struct con_driver *con = &registered_con_driver[i];
+
+                if (con->con && !(con->flag & CON_DRIVER_FLAG_BIND)) {
+                        defcsw = con->con;
+                        break;
+                }
+        }
 
-        if (first != -1 && defcsw) {
-                if (first == 0 && last == MAX_NR_CONSOLES - 1)
+        if (!defcsw)
+                goto err;
+
+        while (more) {
+                more = 0;
+
+                for (i = con->first; i <= con->last; i++) {
+                        if (con_driver_map[i] == defcsw) {
+                                if (first == -1)
+                                        first = i;
+                                last = i;
+                                more = 1;
+                        } else if (first != -1)
+                                break;
+                }
+
+                if (first == 0 && last == MAX_NR_CONSOLES -1)
                         deflt = 1;
-                take_over_console(defcsw, first, last, deflt);
+
+                if (first != -1)
+                        bind_con_driver(csw, first, last, deflt);
+
+                first = -1;
+                last = -1;
+                deflt = 0;
         }
+
+err:
+        return 0;
+}
+
+/*
+ * this function is intended to be called by the tty layer only
+ */
+int vt_unbind(int index)
+{
+        const struct consw *csw = NULL;
+        struct con_driver *con;
+        int i, more = 1, first = -1, last = -1, deflt = 0;
+
+        if (index >= MAX_NR_CON_DRIVER)
+                goto err;
+
+        con = &registered_con_driver[index];
+
+        if (!con->con || !(con->flag & CON_DRIVER_FLAG_BIND))
+                goto err;
+
+        csw = con->con;
+
+        while (more) {
+                more = 0;
+
+                for (i = con->first; i <= con->last; i++) {
+                        if (con_driver_map[i] == csw) {
+                                if (first == -1)
+                                        first = i;
+                                last = i;
+                                more = 1;
+                        } else if (first != -1)
+                                break;
+                }
+
+                if (first == 0 && last == MAX_NR_CONSOLES -1)
+                        deflt = 1;
+
+                if (first != -1)
+                        unbind_con_driver(csw, first, last, deflt);
+
+                first = -1;
+                last = -1;
+                deflt = 0;
+        }
+
+err:
+        return 0;
+}
+#else
+int vt_bind(int index)
+{
+        return 0;
+}
+
+int vt_unbind(int index)
+{
+        return 0;
 }
 #endif
 
 /*
+ * this function is intended to be called by the tty layer only
+ */
+int vt_show_drivers(char *buf)
+{
+        int i, j, read, offset = 0, cnt = PAGE_SIZE;
+
+        for (i = 0; i < MAX_NR_CON_DRIVER; i++) {
+                struct con_driver *con_driver = &registered_con_driver[i];
+
+                if (con_driver->con != NULL) {
+                        int sys = 0;
+
+                        if (con_driver->flag & CON_DRIVER_FLAG_BIND) {
+                                sys = 2;
+
+                                for (j = 0; j < MAX_NR_CONSOLES; j++) {
+                                        if (con_driver_map[j] ==
+                                            con_driver->con) {
+                                                sys = 1;
+                                                break;
+                                        }
+                                }
+                        }
+
+                        read = snprintf(buf + offset, cnt, "%i %s: %s\n",
+                                        i, (sys) ? ((sys == 1) ? "B" : "U") :
+                                        "S", con_driver->desc);
+                        offset += read;
+                        cnt -= read;
+                }
+        }
+
+        return offset;
+}
+
+/*
  *      Screen blanking
  */
 
diff --git a/include/linux/console.h b/include/linux/console.h
index d0f8a8009490..3bdf2155e565 100644
--- a/include/linux/console.h
+++ b/include/linux/console.h
@@ -63,9 +63,11 @@ extern const struct consw vga_con;	/* VGA text console */
 extern const struct consw newport_con;  /* SGI Newport console  */
 extern const struct consw prom_con;     /* SPARC PROM console */
 
+int con_is_bound(const struct consw *csw);
+int register_con_driver(const struct consw *csw, int first, int last);
+int unregister_con_driver(const struct consw *csw);
 int take_over_console(const struct consw *sw, int first, int last, int deflt);
 void give_up_console(const struct consw *sw);
-
 /* scroll */
 #define SM_UP       (1)
 #define SM_DOWN     (2)