[PATCH 2/2] i2c: Add message transfer tracepoints for SMBUS

David Howells
2014-01-09T21:51:05Z

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=51 f=00 c=fa BYTE_DATA
... smbus_reply: i2c-0 a=51 f=00 c=fa BYTE_DATA l=1 [39]
... smbus_result: i2c-0 a=51 f=00 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>
---

drivers/i2c/i2c-core.c | 23 ++++-
include/trace/events/i2c.h | 224 ++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 243 insertions(+), 4 deletions(-)

diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index c8b97490461d..619910632d26 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -2552,6 +2552,14 @@ 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) {
@@ -2572,15 +2580,24 @@ 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);

diff --git a/include/trace/events/i2c.h b/include/trace/events/i2c.h
index d30f008527b2..222aae9c6e3d 100644
--- a/include/trace/events/i2c.h
+++ b/include/trace/events/i2c.h
@@ -1,4 +1,4 @@
-/* I2C message transfer tracepoints
+/* I2C and SMBUS message transfer tracepoints
*
* Copyright (C) 2013 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
@@ -144,6 +144,228 @@ TRACE_EVENT_FN(i2c_result,
i2c_transfer_trace_reg,
i2c_transfer_trace_unreg);

+/*
+ * i2c_smbus_xfer() write data or procedure call request
+ */
+TRACE_EVENT_CONDITION(smbus_write,
+ TP_PROTO(const struct i2c_adapter *adap,
+ u16 addr, unsigned short flags,
+ char read_write, u8 command, int protocol,
+ const union i2c_smbus_data *data),
+ TP_ARGS(adap, addr, flags, read_write, command, protocol, data),
+ TP_CONDITION(read_write == I2C_SMBUS_WRITE ||
+ protocol == I2C_SMBUS_PROC_CALL ||
+ protocol == I2C_SMBUS_BLOCK_PROC_CALL),
+ TP_STRUCT__entry(
+ __field(int, adapter_nr )
+ __field(__u16, addr )
+ __field(__u16, flags )
+ __field(__u8, command )
+ __field(__u8, len )
+ __field(__u32, protocol )
+ __array(__u8, buf, I2C_SMBUS_BLOCK_MAX + 2) ),
+ TP_fast_assign(
+ __entry->adapter_nr = adap->nr;
+ __entry->addr = addr;
+ __entry->flags = flags;
+ __entry->command = command;
+ __entry->protocol = protocol;
+
+ switch (protocol) {
+ case I2C_SMBUS_BYTE_DATA:
+ __entry->len = 1;
+ goto copy;
+ case I2C_SMBUS_WORD_DATA:
+ case I2C_SMBUS_PROC_CALL:
+ __entry->len = 2;
+ goto copy;
+ case I2C_SMBUS_BLOCK_DATA:
+ case I2C_SMBUS_BLOCK_PROC_CALL:
+ case I2C_SMBUS_I2C_BLOCK_DATA:
+ __entry->len = data->block[0] + 1;
+ copy:
+ memcpy(__entry->buf, data->block, __entry->len);
+ break;
+ case I2C_SMBUS_QUICK:
+ case I2C_SMBUS_BYTE:
+ case I2C_SMBUS_I2C_BLOCK_BROKEN:
+ default:
+ __entry->len = 0;
+ }
+ ),
+ TP_printk("i2c-%d a=%02x f=%02x c=%x %s l=%u [%*phN]",
+ __entry->adapter_nr,
+ __entry->addr,
+ __entry->flags,
+ __entry->command,
+ __print_symbolic(__entry->protocol,
+ { I2C_SMBUS_QUICK, "QUICK" },
+ { I2C_SMBUS_BYTE, "BYTE" },
+ { I2C_SMBUS_BYTE_DATA, "BYTE_DATA" },
+ { I2C_SMBUS_WORD_DATA, "WORD_DATA" },
+ { I2C_SMBUS_PROC_CALL, "PROC_CALL" },
+ { I2C_SMBUS_BLOCK_DATA, "BLOCK_DATA" },
+ { I2C_SMBUS_I2C_BLOCK_BROKEN, "I2C_BLOCK_BROKEN" },
+ { I2C_SMBUS_BLOCK_PROC_CALL, "BLOCK_PROC_CALL" },
+ { I2C_SMBUS_I2C_BLOCK_DATA, "I2C_BLOCK_DATA" }),
+ __entry->len,
+ __entry->len, __entry->buf
+ ));
+
+/*
+ * i2c_smbus_xfer() read data request
+ */
+TRACE_EVENT_CONDITION(smbus_read,
+ TP_PROTO(const struct i2c_adapter *adap,
+ u16 addr, unsigned short flags,
+ char read_write, u8 command, int protocol),
+ TP_ARGS(adap, addr, flags, read_write, command, protocol),
+ TP_CONDITION(!(read_write == I2C_SMBUS_WRITE ||
+ protocol == I2C_SMBUS_PROC_CALL ||
+ protocol == I2C_SMBUS_BLOCK_PROC_CALL)),
+ TP_STRUCT__entry(
+ __field(int, adapter_nr )
+ __field(__u16, addr )
+ __field(__u16, flags )
+ __field(__u8, command )
+ __field(__u32, protocol )
+ __array(__u8, buf, I2C_SMBUS_BLOCK_MAX + 2) ),
+ TP_fast_assign(
+ __entry->adapter_nr = adap->nr;
+ __entry->addr = addr;
+ __entry->flags = flags;
+ __entry->command = command;
+ __entry->protocol = protocol;
+ ),
+ TP_printk("i2c-%d a=%02x f=%02x c=%x %s",
+ __entry->adapter_nr,
+ __entry->addr,
+ __entry->flags,
+ __entry->command,
+ __print_symbolic(__entry->protocol,
+ { I2C_SMBUS_QUICK, "QUICK" },
+ { I2C_SMBUS_BYTE, "BYTE" },
+ { I2C_SMBUS_BYTE_DATA, "BYTE_DATA" },
+ { I2C_SMBUS_WORD_DATA, "WORD_DATA" },
+ { I2C_SMBUS_PROC_CALL, "PROC_CALL" },
+ { I2C_SMBUS_BLOCK_DATA, "BLOCK_DATA" },
+ { I2C_SMBUS_I2C_BLOCK_BROKEN, "I2C_BLOCK_BROKEN" },
+ { I2C_SMBUS_BLOCK_PROC_CALL, "BLOCK_PROC_CALL" },
+ { I2C_SMBUS_I2C_BLOCK_DATA, "I2C_BLOCK_DATA" })
+ ));
+
+/*
+ * i2c_smbus_xfer() read data or procedure call reply
+ */
+TRACE_EVENT_CONDITION(smbus_reply,
+ TP_PROTO(const struct i2c_adapter *adap,
+ u16 addr, unsigned short flags,
+ char read_write, u8 command, int protocol,
+ const union i2c_smbus_data *data),
+ TP_ARGS(adap, addr, flags, read_write, command, protocol, data),
+ TP_CONDITION(read_write == I2C_SMBUS_READ),
+ TP_STRUCT__entry(
+ __field(int, adapter_nr )
+ __field(__u16, addr )
+ __field(__u16, flags )
+ __field(__u8, command )
+ __field(__u8, len )
+ __field(__u32, protocol )
+ __array(__u8, buf, I2C_SMBUS_BLOCK_MAX + 2) ),
+ TP_fast_assign(
+ __entry->adapter_nr = adap->nr;
+ __entry->addr = addr;
+ __entry->flags = flags;
+ __entry->command = command;
+ __entry->protocol = protocol;
+
+ switch (protocol) {
+ case I2C_SMBUS_BYTE:
+ case I2C_SMBUS_BYTE_DATA:
+ __entry->len = 1;
+ goto copy;
+ case I2C_SMBUS_WORD_DATA:
+ case I2C_SMBUS_PROC_CALL:
+ __entry->len = 2;
+ goto copy;
+ case I2C_SMBUS_BLOCK_DATA:
+ case I2C_SMBUS_BLOCK_PROC_CALL:
+ case I2C_SMBUS_I2C_BLOCK_DATA:
+ __entry->len = data->block[0] + 1;
+ copy:
+ memcpy(__entry->buf, data->block, __entry->len);
+ break;
+ case I2C_SMBUS_QUICK:
+ case I2C_SMBUS_I2C_BLOCK_BROKEN:
+ default:
+ __entry->len = 0;
+ }
+ ),
+ TP_printk("i2c-%d a=%02x f=%02x c=%x %s l=%u [%*phN]",
+ __entry->adapter_nr,
+ __entry->addr,
+ __entry->flags,
+ __entry->command,
+ __print_symbolic(__entry->protocol,
+ { I2C_SMBUS_QUICK, "QUICK" },
+ { I2C_SMBUS_BYTE, "BYTE" },
+ { I2C_SMBUS_BYTE_DATA, "BYTE_DATA" },
+ { I2C_SMBUS_WORD_DATA, "WORD_DATA" },
+ { I2C_SMBUS_PROC_CALL, "PROC_CALL" },
+ { I2C_SMBUS_BLOCK_DATA, "BLOCK_DATA" },
+ { I2C_SMBUS_I2C_BLOCK_BROKEN, "I2C_BLOCK_BROKEN" },
+ { I2C_SMBUS_BLOCK_PROC_CALL, "BLOCK_PROC_CALL" },
+ { I2C_SMBUS_I2C_BLOCK_DATA, "I2C_BLOCK_DATA" }),
+ __entry->len,
+ __entry->len, __entry->buf
+ ));
+
+/*
+ * i2c_smbus_xfer() result
+ */
+TRACE_EVENT(smbus_result,
+ TP_PROTO(const struct i2c_adapter *adap,
+ u16 addr, unsigned short flags,
+ char read_write, u8 command, int protocol,
+ int res),
+ TP_ARGS(adap, addr, flags, read_write, command, protocol, res),
+ TP_STRUCT__entry(
+ __field(int, adapter_nr )
+ __field(__u16, addr )
+ __field(__u16, flags )
+ __field(__u8, read_write )
+ __field(__u8, command )
+ __field(__s16, res )
+ __field(__u32, protocol )
+ ),
+ TP_fast_assign(
+ __entry->adapter_nr = adap->nr;
+ __entry->addr = addr;
+ __entry->flags = flags;
+ __entry->read_write = read_write;
+ __entry->command = command;
+ __entry->protocol = protocol;
+ __entry->res = res;
+ ),
+ TP_printk("i2c-%d a=%02x f=%02x c=%x %s %s res=%d",
+ __entry->adapter_nr,
+ __entry->addr,
+ __entry->flags,
+ __entry->command,
+ __print_symbolic(__entry->protocol,
+ { I2C_SMBUS_QUICK, "QUICK" },
+ { I2C_SMBUS_BYTE, "BYTE" },
+ { I2C_SMBUS_BYTE_DATA, "BYTE_DATA" },
+ { I2C_SMBUS_WORD_DATA, "WORD_DATA" },
+ { I2C_SMBUS_PROC_CALL, "PROC_CALL" },
+ { I2C_SMBUS_BLOCK_DATA, "BLOCK_DATA" },
+ { I2C_SMBUS_I2C_BLOCK_BROKEN, "I2C_BLOCK_BROKEN" },
+ { I2C_SMBUS_BLOCK_PROC_CALL, "BLOCK_PROC_CALL" },
+ { I2C_SMBUS_I2C_BLOCK_DATA, "I2C_BLOCK_DATA" }),
+ __entry->read_write == I2C_SMBUS_WRITE ? "wr" : "rd",
+ __entry->res
+ ));
+
#endif /* _TRACE_I2C_H */

/* This part must be outside protection */