[PATCH 2/2] tty: n_gsm: Add GSMIOC_DISCONNECT ioctl to disconnect the multiplexer

[Sascha Hauer]

Signed-off-by: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
---
 Documentation/serial/n_gsm.txt | 14 ++++++++++----
 drivers/tty/n_gsm.c            |  2 ++
 include/uapi/linux/gsmmux.h    |  1 +
 3 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/Documentation/serial/n_gsm.txt b/Documentation/serial/n_gsm.txt
index 875361bb7cb4..f81bb5110557 100644
--- a/Documentation/serial/n_gsm.txt
+++ b/Documentation/serial/n_gsm.txt
@@ -79,10 +79,16 @@ for example, it's possible :
 
 Note that after closing the physical port the modem is still in multiplexing
 mode. This may prevent a successful re-opening of the port later. To avoid
-this situation either reset the modem if your hardware allows that or send
-a disconnect command frame manually before initializing the multiplexing mode
-for the second time. The byte sequence for the disconnect command frame is:
-0xf9, 0x03, 0xef, 0x03, 0xc3, 0x16, 0xf9.
+this situation you can
+a) reset the modem if your hardware allows that
+b) send a disconnect command frame manually before initializing the
+   multiplexing mode for the second time
+or
+c) close the connection with the GSMIOC_DISCONNECT ioctl before closing the
+   physical port.
+
+The byte sequence for the disconnect command frame is: 0xf9, 0x03, 0xef, 0x03,
+0xc3, 0x16, 0xf9.
 
 Additional Documentation
 ------------------------
diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
index 363a8ca824ad..31b2cc3c18ea 100644
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -2602,6 +2602,8 @@ static int gsmld_ioctl(struct tty_struct *tty, struct file *file,
 		if (copy_from_user(&c, (void *)arg, sizeof(c)))
 			return -EFAULT;
 		return gsmld_config(tty, gsm, &c);
+	case GSMIOC_DISCONNECT:
+		return gsm_disconnect(gsm);
 	default:
 		return n_tty_ioctl_helper(tty, file, cmd, arg);
 	}
diff --git a/include/uapi/linux/gsmmux.h b/include/uapi/linux/gsmmux.h
index ab055d8cddef..deb98a2ec626 100644
--- a/include/uapi/linux/gsmmux.h
+++ b/include/uapi/linux/gsmmux.h
@@ -24,6 +24,7 @@ struct gsm_config
 
 #define GSMIOC_GETCONF		_IOR('G', 0, struct gsm_config)
 #define GSMIOC_SETCONF		_IOW('G', 1, struct gsm_config)
+#define GSMIOC_DISCONNECT	_IO('G', 2)
 
 struct gsm_netconfig {
 	unsigned int adaption;  /* Adaption to use in network mode */
-- 
2.11.0