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>

1 files changed, 0 insertions, 196 deletions

diff --git a/Documentation/connector/connector.txt b/Documentation/connector/connector.txt
deleted file mode 100644
index ab7ca897fab7..000000000000
--- a/Documentation/connector/connector.txt
+++ /dev/null
@@ -1,196 +0,0 @@
-/*****************************************/
-Kernel Connector.
-/*****************************************/
-
-Kernel connector - new netlink based userspace <-> kernel space easy
-to use communication module.
-
-The Connector driver makes it easy to connect various agents using a
-netlink based network.  One must register a callback and an identifier.
-When the driver receives a special netlink message with the appropriate
-identifier, the appropriate callback will be called.
-
-From the userspace point of view it's quite straightforward:
-
-	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:
-
-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
-{
-	__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
-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 *.
-
-struct cn_msg
-{
-	struct cb_id		id;
-
-	__u32			seq;
-	__u32			ack;
-
-	__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.
-
- 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.
-
- Note: When registering new callback user, connector core assigns
- netlink group to the user which is equal to its id.idx.
-
-/*****************************************/
-Protocol description.
-/*****************************************/
-
-The current framework offers a transport layer with fixed headers.  The
-recommended protocol which uses such a header is as following:
-
-msg->seq and msg->ack are used to determine message genealogy.  When
-someone sends a message, they use a locally unique sequence and random
-acknowledge number.  The sequence number may be copied into
-nlmsghdr->nlmsg_seq too.
-
-The sequence number is incremented with each message sent.
-
-If you expect a reply to the message, then the sequence number in the
-received message MUST be the same as in the original message, and the
-acknowledge number MUST be the same + 1.
-
-If we receive a message and its sequence number is not equal to one we
-are expecting, then it is a new message.  If we receive a message and
-its sequence number is the same as one we are expecting, but its
-acknowledge is not equal to the sequence number in the original
-message + 1, then it is a new message.
-
-Obviously, the protocol header contains the above id.
-
-The connector allows event notification in the following form: kernel
-driver or userspace process can ask connector to notify it when
-selected ids will be turned on or off (registered or unregistered its
-callback).  It is done by sending a special command to the connector
-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.
-/*****************************************/
-
-Netlink itself is not a reliable protocol.  That means that messages can
-be lost due to memory pressure or process' receiving queue overflowed,
-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.
-/*****************************************/
-
-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:
-
-s = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_CONNECTOR);
-
-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) {
-	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
-option with the NETLINK_DROP_MEMBERSHIP parameter which is defined as 0.
-
-2.6.14 netlink code only allows to select a group which is less or equal to
-the maximum group number, which is used at netlink_kernel_create() time.
-In case of connector it is CN_NETLINK_USERS + 0xf, so if you want to use
-group number 12345, you must increment CN_NETLINK_USERS to that number.
-Additional 0xf numbers are allocated to be used by non-in-kernel users.
-
-Due to this limitation, group 0xffffffff does not work now, so one can
-not use add/remove connector's group notifications, but as far as I know, 
-only cn_test.c test module used it.
-
-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
-and CONFIG_SAMPLES.