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| author | David Howells <dhowells@redhat.com> | 2014-03-06 13:36:06 +0000 |
|---|---|---|
| committer | Wolfram Sang <wsa@the-dreams.de> | 2014-03-13 22:15:07 +0100 |
| commit | 8a325997d95d446206b204b7859e055a0315e4fa (patch) | |
| tree | c14cb0b0af6cd80229a6fea12b0b5ca76a1ecaac /drivers/i2c | |
| parent | d9a83d62b326574fb4831b64317a82a42642a9a2 (diff) | |
| download | lwn-8a325997d95d446206b204b7859e055a0315e4fa.tar.gz lwn-8a325997d95d446206b204b7859e055a0315e4fa.zip | |
i2c: Add message transfer tracepoints for SMBUS [ver #2]
The SMBUS tracepoints can be enabled thusly:
echo 1 >/sys/kernel/debug/tracing/events/i2c/enable
and will dump messages that can be viewed in /sys/kernel/debug/tracing/trace
that look like:
... smbus_read: i2c-0 a=051 f=0000 c=fa BYTE_DATA
... smbus_reply: i2c-0 a=051 f=0000 c=fa BYTE_DATA l=1 [39]
... smbus_result: i2c-0 a=051 f=0000 c=fa BYTE_DATA rd res=0
formatted as:
i2c-<adapter-nr>
a=<addr>
f=<flags>
c=<command>
<protocol-name>
<rd|wr>
res=<result>
l=<data-len>
[<data-block>]
The adapters to be traced can be selected by something like:
echo adapter_nr==1 >/sys/kernel/debug/tracing/events/i2c/filter
Note that this shares the same filter and enablement as i2c.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Diffstat (limited to 'drivers/i2c')
| -rw-r--r-- | drivers/i2c/i2c-core.c | 23 |
1 files changed, 20 insertions, 3 deletions
diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c index bdedbee85c01..7c7f4b856bad 100644 --- a/drivers/i2c/i2c-core.c +++ b/drivers/i2c/i2c-core.c @@ -2565,6 +2565,14 @@ s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr, unsigned short flags, int try; s32 res; + /* If enabled, the following two tracepoints are conditional on + * read_write and protocol. + */ + trace_smbus_write(adapter, addr, flags, read_write, + command, protocol, data); + trace_smbus_read(adapter, addr, flags, read_write, + command, protocol); + flags &= I2C_M_TEN | I2C_CLIENT_PEC | I2C_CLIENT_SCCB; if (adapter->algo->smbus_xfer) { @@ -2585,15 +2593,24 @@ s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr, unsigned short flags, i2c_unlock_adapter(adapter); if (res != -EOPNOTSUPP || !adapter->algo->master_xfer) - return res; + goto trace; /* * Fall back to i2c_smbus_xfer_emulated if the adapter doesn't * implement native support for the SMBus operation. */ } - return i2c_smbus_xfer_emulated(adapter, addr, flags, read_write, - command, protocol, data); + res = i2c_smbus_xfer_emulated(adapter, addr, flags, read_write, + command, protocol, data); + +trace: + /* If enabled, the reply tracepoint is conditional on read_write. */ + trace_smbus_reply(adapter, addr, flags, read_write, + command, protocol, data); + trace_smbus_result(adapter, addr, flags, read_write, + command, protocol, res); + + return res; } EXPORT_SYMBOL(i2c_smbus_xfer); |