1 files changed, 43 insertions, 4 deletions
diff --git a/Documentation/networking/phonet.txt b/Documentation/networking/phonet.txt
index 6a07e45d4a9..81003581f47 100644
--- a/Documentation/networking/phonet.txt
+++ b/Documentation/networking/phonet.txt
@@ -36,7 +36,7 @@ Phonet packets have a common header as follows:
 On Linux, the link-layer header includes the pn_media byte (see below).
 The next 7 bytes are part of the network-layer header.
 
-The device ID is split: the 6 higher-order bits consitute the device
+The device ID is split: the 6 higher-order bits constitute the device
 address, while the 2 lower-order bits are used for multiplexing, as are
 the 8-bit object identifiers. As such, Phonet can be considered as a
 network layer with 6 bits of address space and 10 bits for transport
@@ -112,6 +112,22 @@ However, connect() and getpeername() are not supported, as they did
 not seem useful with Phonet usages (could be added easily).
 
 
+Resource subscription
+---------------------
+
+A Phonet datagram socket can be subscribed to any number of 8-bits
+Phonet resources, as follow:
+
+  uint32_t res = 0xXX;
+  ioctl(fd, SIOCPNADDRESOURCE, &res);
+
+Subscription is similarly cancelled using the SIOCPNDELRESOURCE I/O
+control request, or when the socket is closed.
+
+Note that no more than one socket can be subcribed to any given
+resource at a time. If not, ioctl() will return EBUSY.
+
+
 Phonet Pipe protocol
 --------------------
 
@@ -138,9 +154,28 @@ connections, one per accept()'d socket.
     write(cfd, msg, msglen);
   }
 
-Connections are established between two endpoints by a "third party"
-application. This means that both endpoints are passive; so connect()
-is not possible.
+Connections are traditionally established between two endpoints by a
+"third party" application. This means that both endpoints are passive.
+
+
+As of Linux kernel version 2.6.39, it is also possible to connect
+two endpoints directly, using connect() on the active side. This is
+intended to support the newer Nokia Wireless Modem API, as found in
+e.g. the Nokia Slim Modem in the ST-Ericsson U8500 platform:
+
+  struct sockaddr_spn spn;
+  int fd;
+
+  fd = socket(PF_PHONET, SOCK_SEQPACKET, PN_PROTO_PIPE);
+  memset(&spn, 0, sizeof(spn));
+  spn.spn_family = AF_PHONET;
+  spn.spn_obj = ...;
+  spn.spn_dev = ...;
+  spn.spn_resource = 0xD9;
+  connect(fd, (struct sockaddr *)&spn, sizeof(spn));
+  /* normal I/O here ... */
+  close(fd);
+
 
 WARNING:
 When polling a connected pipe socket for writability, there is an
@@ -165,6 +200,10 @@ The pipe protocol provides two socket options at the SOL_PNPIPE level:
     interface index of the network interface created by PNPIPE_ENCAP,
     or zero if encapsulation is off.
 
+  PNPIPE_HANDLE is a read-only integer value. It contains the underlying
+    identifier ("pipe handle") of the pipe. This is only defined for
+    socket descriptors that are already connected or being connected.
+
 
 Authors
 -------