tty: n_gsm: expose gsmtty device nodes at ldisc open time

The n_gsm driver being an ldisc, does not provide a convenient method
e.g. udev to create the tty device nodes automatically when the ldisc
is opened.

The TTY device nodes are now created via calls to tty_register_device
from the ldisc open.

Signed-off-by: Russ Gorby <russ.gorby@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
index 09e8c7d53af3e7d72ebfe25b45100789f4f5185a..b288ff6cb8128347b15deaf361a45179b13a86d2 100644 (file)
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -169,6 +169,7 @@ struct gsm_control {
 struct gsm_mux {
        struct tty_struct *tty;         /* The tty our ldisc is bound to */
        spinlock_t lock;
+       unsigned int num;
 
        /* Events on the GSM channel */
        wait_queue_head_t event;
@@ -250,6 +251,8 @@ struct gsm_mux {
 static struct gsm_mux *gsm_mux[MAX_MUX];       /* GSM muxes */
 static spinlock_t gsm_mux_lock;
 
+static struct tty_driver *gsm_tty_driver;
+
 /*
  *     This section of the driver logic implements the GSM encodings
  *     both the basic and the 'advanced'. Reliable transport is not
@@ -1996,6 +1999,7 @@ int gsm_activate_mux(struct gsm_mux *gsm)
        spin_lock(&gsm_mux_lock);
        for (i = 0; i < MAX_MUX; i++) {
                if (gsm_mux[i] == NULL) {
+                       gsm->num = i;
                        gsm_mux[i] = gsm;
                        break;
                }
@@ -2101,13 +2105,20 @@ static int gsmld_output(struct gsm_mux *gsm, u8 *data, int len)
 
 static int gsmld_attach_gsm(struct tty_struct *tty, struct gsm_mux *gsm)
 {
-       int ret;
+       int ret, i;
+       int base = gsm->num << 6; /* Base for this MUX */
 
        gsm->tty = tty_kref_get(tty);
        gsm->output = gsmld_output;
        ret =  gsm_activate_mux(gsm);
        if (ret != 0)
                tty_kref_put(gsm->tty);
+       else {
+               /* Don't register device 0 - this is the control channel and not
+                  a usable tty interface */
+               for (i = 1; i < NUM_DLCI; i++)
+                       tty_register_device(gsm_tty_driver, base + i, NULL);
+       }
        return ret;
 }
 
@@ -2122,7 +2133,12 @@ static int gsmld_attach_gsm(struct tty_struct *tty, struct gsm_mux *gsm)
 
 static void gsmld_detach_gsm(struct tty_struct *tty, struct gsm_mux *gsm)
 {
+       int i;
+       int base = gsm->num << 6; /* Base for this MUX */
+
        WARN_ON(tty != gsm->tty);
+       for (i = 1; i < NUM_DLCI; i++)
+               tty_unregister_device(gsm_tty_driver, base + i);
        gsm_cleanup_mux(gsm);
        tty_kref_put(gsm->tty);
        gsm->tty = NULL;
@@ -2712,7 +2728,6 @@ static int gsmtty_break_ctl(struct tty_struct *tty, int state)
        return gsmtty_modem_update(dlci, encode);
 }
 
-static struct tty_driver *gsm_tty_driver;
 
 /* Virtual ttys for the demux */
 static const struct tty_operations gsmtty_ops = {