docs: connector: convert to ReST and rename to connector.rst

As it has some function definitions, move them to connector.h.

The remaining conversion is actually:
  - add blank lines and identation in order to identify paragraphs;
  - fix tables markups;
  - add some lists markups;
  - mark literal blocks;
  - adjust title markups.

At its new index.rst, let's add a :orphan: while this is not linked to
the main index.rst file, in order to avoid build warnings.
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

Documentation/connector/connector.txt → Documentation/connector/connector.rst

-/*****************************************/
-Kernel Connector.
-/*****************************************/
+:orphan:
+
+================
+Kernel Connector
+================
 
 Kernel connector - new netlink based userspace <-> kernel space easy
 to use communication module.
@@ -12,35 +14,35 @@ identifier, the appropriate callback will be called.
 
 From the userspace point of view it's quite straightforward:
 
-	socket();
-	bind();
-	send();
-	recv();
+	- socket();
+	- bind();
+	- send();
+	- recv();
 
 But if kernelspace wants to use the full power of such connections, the
 driver writer must create special sockets, must know about struct sk_buff
 handling, etc...  The Connector driver allows any kernelspace agents to use
 netlink based networking for inter-process communication in a significantly
-easier way:
+easier way::
 
-int cn_add_callback(struct cb_id *id, char *name, void (*callback) (struct cn_msg *, struct netlink_skb_parms *));
-void cn_netlink_send_multi(struct cn_msg *msg, u16 len, u32 portid, u32 __group, int gfp_mask);
-void cn_netlink_send(struct cn_msg *msg, u32 portid, u32 __group, int gfp_mask);
+  int cn_add_callback(struct cb_id *id, char *name, void (*callback) (struct cn_msg *, struct netlink_skb_parms *));
+  void cn_netlink_send_multi(struct cn_msg *msg, u16 len, u32 portid, u32 __group, int gfp_mask);
+  void cn_netlink_send(struct cn_msg *msg, u32 portid, u32 __group, int gfp_mask);
 
-struct cb_id
-{
+  struct cb_id
+  {
 	__u32			idx;
 	__u32			val;
-};
+  };
 
 idx and val are unique identifiers which must be registered in the
-connector.h header for in-kernel usage.  void (*callback) (void *) is a
+connector.h header for in-kernel usage.  `void (*callback) (void *)` is a
 callback function which will be called when a message with above idx.val
 is received by the connector core.  The argument for that function must
-be dereferenced to struct cn_msg *.
+be dereferenced to `struct cn_msg *`::
 
-struct cn_msg
-{
+  struct cn_msg
+  {
 	struct cb_id		id;
 
 	__u32			seq;
@@ -48,58 +50,19 @@ struct cn_msg
 
 	__u32			len;	/* Length of the following data */
 	__u8			data[0];
-};
-
-/*****************************************/
-Connector interfaces.
-/*****************************************/
-
-int cn_add_callback(struct cb_id *id, char *name, void (*callback) (struct cn_msg *, struct netlink_skb_parms *));
-
- Registers new callback with connector core.
-
- struct cb_id *id		- unique connector's user identifier.
-				  It must be registered in connector.h for legal in-kernel users.
- char *name			- connector's callback symbolic name.
- void (*callback) (struct cn..)	- connector's callback.
-				  cn_msg and the sender's credentials
-
-
-void cn_del_callback(struct cb_id *id);
-
- Unregisters new callback with connector core.
-
- struct cb_id *id		- unique connector's user identifier.
-
-
-int cn_netlink_send_multi(struct cn_msg *msg, u16 len, u32 portid, u32 __groups, int gfp_mask);
-int cn_netlink_send(struct cn_msg *msg, u32 portid, u32 __groups, int gfp_mask);
+  };
 
- Sends message to the specified groups.  It can be safely called from
- softirq context, but may silently fail under strong memory pressure.
- If there are no listeners for given group -ESRCH can be returned.
+Connector interfaces
+====================
 
- struct cn_msg *		- message header(with attached data).
- u16 len			- for *_multi multiple cn_msg messages can be sent
- u32 port			- destination port.
- 				  If non-zero the message will be sent to the
-				  given port, which should be set to the
-				  original sender.
- u32 __group			- destination group.
-				  If port and __group is zero, then appropriate group will
-				  be searched through all registered connector users,
-				  and message will be delivered to the group which was
-				  created for user with the same ID as in msg.
-				  If __group is not zero, then message will be delivered
-				  to the specified group.
- int gfp_mask			- GFP mask.
+ .. kernel-doc:: include/linux/connector.h
 
- Note: When registering new callback user, connector core assigns
+ Note:
+   When registering new callback user, connector core assigns
    netlink group to the user which is equal to its id.idx.
 
-/*****************************************/
-Protocol description.
-/*****************************************/
+Protocol description
+====================
 
 The current framework offers a transport layer with fixed headers.  The
 recommended protocol which uses such a header is as following:
@@ -132,9 +95,8 @@ driver (it also registers itself with id={-1, -1}).
 As example of this usage can be found in the cn_test.c module which
 uses the connector to request notification and to send messages.
 
-/*****************************************/
-Reliability.
-/*****************************************/
+Reliability
+===========
 
 Netlink itself is not a reliable protocol.  That means that messages can
 be lost due to memory pressure or process' receiving queue overflowed,
@@ -142,32 +104,31 @@ so caller is warned that it must be prepared.  That is why the struct
 cn_msg [main connector's message header] contains u32 seq and u32 ack
 fields.
 
-/*****************************************/
-Userspace usage.
-/*****************************************/
+Userspace usage
+===============
 
 2.6.14 has a new netlink socket implementation, which by default does not
 allow people to send data to netlink groups other than 1.
 So, if you wish to use a netlink socket (for example using connector)
 with a different group number, the userspace application must subscribe to
-that group first.  It can be achieved by the following pseudocode:
+that group first.  It can be achieved by the following pseudocode::
 
-s = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_CONNECTOR);
+  s = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_CONNECTOR);
 
-l_local.nl_family = AF_NETLINK;
-l_local.nl_groups = 12345;
-l_local.nl_pid = 0;
+  l_local.nl_family = AF_NETLINK;
+  l_local.nl_groups = 12345;
+  l_local.nl_pid = 0;
 
-if (bind(s, (struct sockaddr *)&l_local, sizeof(struct sockaddr_nl)) == -1) {
+  if (bind(s, (struct sockaddr *)&l_local, sizeof(struct sockaddr_nl)) == -1) {
 	perror("bind");
 	close(s);
 	return -1;
-}
+  }
 
-{
+  {
 	int on = l_local.nl_groups;
 	setsockopt(s, 270, 1, &on, sizeof(on));
-}
+  }
 
 Where 270 above is SOL_NETLINK, and 1 is a NETLINK_ADD_MEMBERSHIP socket
 option.  To drop a multicast subscription, one should call the above socket
@@ -187,9 +148,8 @@ Some work in netlink area is still being done, so things can be changed in
 2.6.15 timeframe, if it will happen, documentation will be updated for that
 kernel.
 
-/*****************************************/
 Code samples
-/*****************************************/
+============
 
 Sample code for a connector test module and user space can be found
 in samples/connector/. To build this code, enable CONFIG_CONNECTOR

drivers/w1/Kconfig

@@ -19,7 +19,7 @@ config W1_CON
 	default y
 	---help---
 	  This allows to communicate with userspace using connector. For more
-	  information see <file:Documentation/connector/connector.txt>.
+	  information see <file:Documentation/connector/connector.rst>.
 	  There are three types of messages between w1 core and userspace:
 	  1. Events. They are generated each time new master or slave device found
 		either due to automatic or requested search.

include/linux/connector.h

@@ -55,10 +55,71 @@ struct cn_dev {
 	struct cn_queue_dev *cbdev;
 };
 
+/**
+ * cn_add_callback() - Registers new callback with connector core.
+ *
+ * @id:		unique connector's user identifier.
+ *		It must be registered in connector.h for legal
+ *		in-kernel users.
+ * @name:	connector's callback symbolic name.
+ * @callback:	connector's callback.
+ * 		parameters are %cn_msg and the sender's credentials
+ */
 int cn_add_callback(struct cb_id *id, const char *name,
 		    void (*callback)(struct cn_msg *, struct netlink_skb_parms *));
-void cn_del_callback(struct cb_id *);
+/**
+ * cn_del_callback() - Unregisters new callback with connector core.
+ *
+ * @id:		unique connector's user identifier.
+ */
+void cn_del_callback(struct cb_id *id);
+
+
+/**
+ * cn_netlink_send_mult - Sends message to the specified groups.
+ *
+ * @msg: 	message header(with attached data).
+ * @len:	Number of @msg to be sent.
+ * @portid:	destination port.
+ *		If non-zero the message will be sent to the given port,
+ *		which should be set to the original sender.
+ * @group:	destination group.
+ * 		If @portid and @group is zero, then appropriate group will
+ *		be searched through all registered connector users, and
+ *		message will be delivered to the group which was created
+ *		for user with the same ID as in @msg.
+ *		If @group is not zero, then message will be delivered
+ *		to the specified group.
+ * @gfp_mask:	GFP mask.
+ *
+ * It can be safely called from softirq context, but may silently
+ * fail under strong memory pressure.
+ *
+ * If there are no listeners for given group %-ESRCH can be returned.
+ */
 int cn_netlink_send_mult(struct cn_msg *msg, u16 len, u32 portid, u32 group, gfp_t gfp_mask);
+
+/**
+ * cn_netlink_send_mult - Sends message to the specified groups.
+ *
+ * @msg:	message header(with attached data).
+ * @portid:	destination port.
+ *		If non-zero the message will be sent to the given port,
+ *		which should be set to the original sender.
+ * @group:	destination group.
+ * 		If @portid and @group is zero, then appropriate group will
+ *		be searched through all registered connector users, and
+ *		message will be delivered to the group which was created
+ *		for user with the same ID as in @msg.
+ *		If @group is not zero, then message will be delivered
+ *		to the specified group.
+ * @gfp_mask:	GFP mask.
+ *
+ * It can be safely called from softirq context, but may silently
+ * fail under strong memory pressure.
+ *
+ * If there are no listeners for given group %-ESRCH can be returned.
+ */
 int cn_netlink_send(struct cn_msg *msg, u32 portid, u32 group, gfp_t gfp_mask);
 
 int cn_queue_add_callback(struct cn_queue_dev *dev, const char *name,

samples/Kconfig

@@ -99,7 +99,7 @@ config SAMPLE_CONNECTOR
 	  When enabled, this builds both a sample kernel module for
 	  the connector interface and a user space tool to communicate
 	  with it.
-	  See also Documentation/connector/connector.txt
+	  See also Documentation/connector/connector.rst
 
 config SAMPLE_HIDRAW
 	bool "hidraw sample"