From 8a325997d95d446206b204b7859e055a0315e4fa Mon Sep 17 00:00:00 2001 From: David Howells Date: Thu, 6 Mar 2014 13:36:06 +0000 Subject: 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- a= f= c= res= l= [] 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 Reviewed-by: Steven Rostedt Signed-off-by: Wolfram Sang --- drivers/i2c/i2c-core.c | 23 ++++++++++++++++++++--- 1 file changed, 20 insertions(+), 3 deletions(-) (limited to 'drivers') 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); -- cgit v1.2.3-59-g8ed1b