lkml.org 
[lkml]   [2009]   [Sep]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 1/4] Documentation: expand isdn/INTERFACE.CAPI document
Date
Describe the storage of CAPI messages and payload data in SKBs,
kernelcapi debugging output, and note that send_message() may
in fact be called in interrupt context.

Signed-off-by: Tilman Schmidt <tilman@imap.cc>
---
Documentation/isdn/INTERFACE.CAPI | 68 ++++++++++++++++++++++++++++++++-----
1 files changed, 59 insertions(+), 9 deletions(-)
diff --git a/Documentation/isdn/INTERFACE.CAPI b/Documentation/isdn/INTERFACE.CAPI
index 686e107..e6bb1a7 100644
--- a/Documentation/isdn/INTERFACE.CAPI
+++ b/Documentation/isdn/INTERFACE.CAPI
@@ -60,10 +60,9 @@ open() operation on regular files or character devices.

After a successful return from register_appl(), CAPI messages from the
application may be passed to the driver for the device via calls to the
-send_message() callback function. The CAPI message to send is stored in the
-data portion of an skb. Conversely, the driver may call Kernel CAPI's
-capi_ctr_handle_message() function to pass a received CAPI message to Kernel
-CAPI for forwarding to an application, specifying its ApplID.
+send_message() callback function. Conversely, the driver may call Kernel
+CAPI's capi_ctr_handle_message() function to pass a received CAPI message to
+Kernel CAPI for forwarding to an application, specifying its ApplID.

Deregistration requests (CAPI operation CAPI_RELEASE) from applications are
forwarded as calls to the release_appl() callback function, passing the same
@@ -142,6 +141,7 @@ u16 (*send_message)(struct capi_ctr *ctrlr, struct sk_buff *skb)
to accepting or queueing the message. Errors occurring during the
actual processing of the message should be signaled with an
appropriate reply message.
+ May be called in process or interrupt context.
Calls to this function are not serialized by Kernel CAPI, ie. it must
be prepared to be re-entered.

@@ -154,7 +154,8 @@ read_proc_t *ctr_read_proc
system entry, /proc/capi/controllers/<n>; will be called with a
pointer to the device's capi_ctr structure as the last (data) argument

-Note: Callback functions are never called in interrupt context.
+Note: Callback functions except send_message() are never called in interrupt
+context.

- to be filled in before calling capi_ctr_ready():

@@ -171,14 +172,40 @@ u8 serial[CAPI_SERIAL_LEN]
value to return for CAPI_GET_SERIAL


-4.3 The _cmsg Structure
+4.3 SKBs
+
+CAPI messages are passed between Kernel CAPI and the driver via send_message()
+and capi_ctr_handle_message(), stored in the data portion of a socket buffer
+(skb). Each skb contains a single CAPI message coded according to the CAPI 2.0
+standard.
+
+For the data transfer messages, DATA_B3_REQ and DATA_B3_IND, the actual
+payload data immediately follows the CAPI message itself within the same skb.
+The Data and Data64 parameters are not used for processing. The Data64
+parameter may be omitted by setting the length field of the CAPI message to 22
+instead of 30.
+
+
+4.4 The _cmsg Structure

(declared in <linux/isdn/capiutil.h>)

The _cmsg structure stores the contents of a CAPI 2.0 message in an easily
-accessible form. It contains members for all possible CAPI 2.0 parameters, of
-which only those appearing in the message type currently being processed are
-actually used. Unused members should be set to zero.
+accessible form. It contains members for all possible CAPI 2.0 parameters,
+including subparameters of the Additional Info and B Protocol structured
+parameters, with the following exceptions:
+
+* second Calling party number (CONNECT_IND)
+
+* Data64 (DATA_B3_REQ and DATA_B3_IND)
+
+* Sending complete (subparameter of Additional Info, CONNECT_REQ and INFO_REQ)
+
+* Global Configuration (subparameter of B Protocol, CONNECT_REQ, CONNECT_RESP
+ and SELECT_B_PROTOCOL_REQ)
+
+Only those parameters appearing in the message type currently being processed
+are actually used. Unused members should be set to zero.

Members are named after the CAPI 2.0 standard names of the parameters they
represent. See <linux/isdn/capiutil.h> for the exact spelling. Member data
@@ -297,3 +324,26 @@ char *capi_cmd2str(u8 Command, u8 Subcommand)
be NULL if the command/subcommand is not one of those defined in the
CAPI 2.0 standard.

+
+7. Debugging
+
+The module kernelcapi has a module parameter showcapimsgs controlling some
+debugging output produced by the module. It can only be set when the module is
+loaded, via a parameter "showcapimsgs=<n>" to the modprobe command, either on
+the command line or in the configuration file.
+
+If the lowest bit of showcapimsgs is set, kernelcapi logs controller and
+application up and down events.
+
+In addition, every registered CAPI controller has an associated traceflag
+parameter controlling how CAPI messages sent from and to tha controller are
+logged. The traceflag parameter is initialized with the value of the
+showcapimsgs parameter when the controller is registered, but can later be
+changed via the MANUFACTURER_REQ command KCAPI_CMD_TRACE.
+
+If the value of traceflag is non-zero, CAPI messages are logged.
+DATA_B3 messages are only logged if the value of traceflag is > 2.
+
+If the lowest bit of traceflag is set, only the command/subcommand and message
+length are logged. Otherwise, kernelcapi logs a readable representation of
+the entire message.
--
1.6.2.1.214.ge986c


\
 
 \ /
  Last update: 2009-09-19 02:07    [from the cache]
©2003-2014 Jasper Spaans. Advertise on this site