tty: n_gsm: add missing description to structs in gsmmux.h

Currently, all available structure fields in gsmmux.h except those
for gsm_config are commented. Furthermore, no kernel doc comments are used.

Fix this by adding appropriate comments to the not commented fields of
gsm_config. Convert the comments of the other structs to kernel doc format.

Note that 'mru' and 'mtu' refer to the size without basic/advanced option
mode header and byte stuffing as defined in the standard in chapter 5.7.2.

Link: https://portal.3gpp.org/desktopmodules/Specifications/SpecificationDetails.aspx?specificationId=1516
Signed-off-by: Daniel Starke <daniel.starke@siemens.com>
Link: https://lore.kernel.org/r/20230817093231.2317-2-daniel.starke@siemens.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 84 insertions, 20 deletions

diff --git a/include/uapi/linux/gsmmux.h b/include/uapi/linux/gsmmux.h
index e56e2d7ea6eb..3bd6f03a8293 100644
--- a/include/uapi/linux/gsmmux.h
+++ b/include/uapi/linux/gsmmux.h
@@ -18,6 +18,28 @@
  */
 #define GSM_FL_RESTART	_BITUL(0)
 
+/**
+ * struct gsm_config - n_gsm basic configuration parameters
+ *
+ * This structure is used in combination with GSMIOC_GETCONF and GSMIOC_SETCONF
+ * to retrieve and set the basic parameters of an n_gsm ldisc.
+ * struct gsm_config_ext can be used to configure extended ldisc parameters.
+ *
+ * All timers are in units of 1/100th of a second.
+ *
+ * @adaption:      Convergence layer type
+ * @encapsulation: Framing (0 = basic option, 1 = advanced option)
+ * @initiator:     Initiator or responder
+ * @t1:            Acknowledgment timer
+ * @t2:            Response timer for multiplexer control channel
+ * @t3:            Response timer for wake-up procedure
+ * @n2:            Maximum number of retransmissions
+ * @mru:           Maximum incoming frame payload size
+ * @mtu:           Maximum outgoing frame payload size
+ * @k:             Window size
+ * @i:             Frame type (1 = UIH, 2 = UI)
+ * @unused:        Can not be used
+ */
 struct gsm_config
 {
 	unsigned int adaption;
@@ -31,18 +53,32 @@ struct gsm_config
 	unsigned int mtu;
 	unsigned int k;
 	unsigned int i;
-	unsigned int unused[8];	/* Can not be used */
+	unsigned int unused[8];
 };
 
 #define GSMIOC_GETCONF		_IOR('G', 0, struct gsm_config)
 #define GSMIOC_SETCONF		_IOW('G', 1, struct gsm_config)
 
+/**
+ * struct gsm_netconfig - n_gsm network configuration parameters
+ *
+ * This structure is used in combination with GSMIOC_ENABLE_NET and
+ * GSMIOC_DISABLE_NET to enable or disable a network data connection
+ * over a mux virtual tty channel. This is for modems that support
+ * data connections with raw IP frames instead of PPP.
+ *
+ * @adaption: Adaption to use in network mode.
+ * @protocol: Protocol to use - only ETH_P_IP supported.
+ * @unused2:  Can not be used.
+ * @if_name:  Interface name format string.
+ * @unused:   Can not be used.
+ */
 struct gsm_netconfig {
-	unsigned int adaption;  /* Adaption to use in network mode */
-	unsigned short protocol;/* Protocol to use - only ETH_P_IP supported */
-	unsigned short unused2;	/* Can not be used */
-	char if_name[IFNAMSIZ];	/* interface name format string */
-	__u8 unused[28];        /* Can not be used */
+	unsigned int adaption;
+	unsigned short protocol;
+	unsigned short unused2;
+	char if_name[IFNAMSIZ];
+	__u8 unused[28];
 };
 
 #define GSMIOC_ENABLE_NET      _IOW('G', 2, struct gsm_netconfig)
@@ -51,27 +87,55 @@ struct gsm_netconfig {
 /* get the base tty number for a configured gsmmux tty */
 #define GSMIOC_GETFIRST		_IOR('G', 4, __u32)
 
+/**
+ * struct gsm_config_ext - n_gsm extended configuration parameters
+ *
+ * This structure is used in combination with GSMIOC_GETCONF_EXT and
+ * GSMIOC_SETCONF_EXT to retrieve and set the extended parameters of an
+ * n_gsm ldisc.
+ *
+ * All timers are in units of 1/100th of a second.
+ *
+ * @keep_alive:  Control channel keep-alive in 1/100th of a second (0 to disable).
+ * @wait_config: Wait for DLCI config before opening virtual link?
+ * @reserved:    For future use, must be initialized to zero.
+ */
 struct gsm_config_ext {
-	__u32 keep_alive;	/* Control channel keep-alive in 1/100th of a
-				 * second (0 to disable)
-				 */
-	__u32 wait_config;	/* Wait for DLCI config before opening virtual link? */
-	__u32 reserved[6];	/* For future use, must be initialized to zero */
+	__u32 keep_alive;
+	__u32 wait_config;
+	__u32 reserved[6];
 };
 
 #define GSMIOC_GETCONF_EXT	_IOR('G', 5, struct gsm_config_ext)
 #define GSMIOC_SETCONF_EXT	_IOW('G', 6, struct gsm_config_ext)
 
-/* Set channel accordingly before calling GSMIOC_GETCONF_DLCI. */
+/**
+ * struct gsm_dlci_config - n_gsm channel configuration parameters
+ *
+ * This structure is used in combination with GSMIOC_GETCONF_DLCI and
+ * GSMIOC_SETCONF_DLCI to retrieve and set the channel specific parameters
+ * of an n_gsm ldisc.
+ *
+ * Set the channel accordingly before calling GSMIOC_GETCONF_DLCI.
+ *
+ * @channel:  DLCI (0 for the associated DLCI).
+ * @adaption: Convergence layer type.
+ * @mtu:      Maximum transfer unit.
+ * @priority: Priority (0 for default value).
+ * @i:        Frame type (1 = UIH, 2 = UI).
+ * @k:        Window size (0 for default value).
+ * @flags:    DLCI specific flags.
+ * @reserved: For future use, must be initialized to zero.
+ */
 struct gsm_dlci_config {
-	__u32 channel;		/* DLCI (0 for the associated DLCI) */
-	__u32 adaption;		/* Convergence layer type */
-	__u32 mtu;		/* Maximum transfer unit */
-	__u32 priority;		/* Priority (0 for default value) */
-	__u32 i;		/* Frame type (1 = UIH, 2 = UI) */
-	__u32 k;		/* Window size (0 for default value) */
-	__u32 flags;		/* DLCI specific flags. */
-	__u32 reserved[7];	/* For future use, must be initialized to zero */
+	__u32 channel;
+	__u32 adaption;
+	__u32 mtu;
+	__u32 priority;
+	__u32 i;
+	__u32 k;
+	__u32 flags;
+	__u32 reserved[7];
 };
 
 #define GSMIOC_GETCONF_DLCI	_IOWR('G', 7, struct gsm_dlci_config)