[PATCH 2/9] tty: n_gsm: add restart parameter to DLC specific ioctl config

["D. Starke" <daniel.starke@siemens.com>]

From: Daniel Starke <daniel.starke@siemens.com>

'gsm_config_ext' already allows to force a link reset via 'restart'
parameter. An equivalent parameter for an forced channel reset is still
missing in 'gsm_dlci_config'. Therefore, the user has no means to perform
an automatic channel reset after parameter configuration for
non-conflicting changes. Conflicting changes automatically reset the
channel already in the current implementation.

Add the parameter 'restart' to 'gsm_dlci_config' to force a channel reset
after ioctl setting regardless of whether the changes made require this or
not.

Note that the parameter is limited to the values 0 and 1 to allow future
additions here.

Signed-off-by: Daniel Starke <daniel.starke@siemens.com>
---
 drivers/tty/n_gsm.c         | 4 ++++
 include/uapi/linux/gsmmux.h | 3 ++-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
index c42c8b89fd46..eb21ca583642 100644
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -2531,6 +2531,8 @@ static int gsm_dlci_config(struct gsm_dlci *dlci, struct gsm_dlci_config *dc, in
 		return -EINVAL;
 	if (dc->k > 7)
 		return -EINVAL;
+	if (dc->restart > 1)   /* allow future extensions */
+		return -EINVAL;
 
 	/*
 	 * See what is needed for reconfiguration
@@ -2545,6 +2547,8 @@ static int gsm_dlci_config(struct gsm_dlci *dlci, struct gsm_dlci_config *dc, in
 	/* Requires care */
 	if (dc->priority != dlci->prio)
 		need_restart = true;
+	if (dc->restart)
+		need_restart = true;
 
 	if ((open && gsm->wait_config) || need_restart)
 		need_open = true;
diff --git a/include/uapi/linux/gsmmux.h b/include/uapi/linux/gsmmux.h
index eb67884e5f38..33ee7b857c52 100644
--- a/include/uapi/linux/gsmmux.h
+++ b/include/uapi/linux/gsmmux.h
@@ -58,7 +58,8 @@ struct gsm_dlci_config {
 	__u32 priority;		/* Priority (0 for default value) */
 	__u32 i;		/* Frame type (1 = UIH, 2 = UI) */
 	__u32 k;		/* Window size (0 for default value) */
-	__u32 reserved[8];	/* For future use, must be initialized to zero */
+	__u32 restart;		/* Force DLCI channel reset? */
+	__u32 reserved[7];	/* For future use, must be initialized to zero */
 };
 
 #define GSMIOC_GETCONF_DLCI	_IOWR('G', 7, struct gsm_dlci_config)
-- 
2.34.1