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Subject[PATCH] i2c: add tracepoints for I2C slave events
Date
I2C slave events tracepoints can be enabled by:

echo 1 > /sys/kernel/tracing/events/i2c_slave/enable

and logs in /sys/kernel/tracing/trace will look like:

... i2c_slave: i2c-0 a=010 WR_REQ []
... i2c_slave: i2c-0 a=010 WR_RCV [02]
... i2c_slave: i2c-0 a=010 WR_RCV [0c]
... i2c_slave: i2c-0 a=010 STOP []
... i2c_slave: i2c-0 a=010 RD_REQ [04]
... i2c_slave: i2c-0 a=010 RD_PRO [b4]
... i2c_slave: i2c-0 a=010 STOP []

formatted as:

i2c-<adapter-nr>
a=<addr>
<event>
[<data>]

trace printings can be selected by adding a filter like:

echo adapter_nr==1 >/sys/kernel/tracing/events/i2c_slave/filter

Signed-off-by: Jae Hyun Yoo <quic_jaehyoo@quicinc.com>
---
drivers/i2c/i2c-core-slave.c | 15 +++++++++
include/linux/i2c.h | 8 ++---
include/trace/events/i2c_slave.h | 57 ++++++++++++++++++++++++++++++++
3 files changed, 74 insertions(+), 6 deletions(-)
create mode 100644 include/trace/events/i2c_slave.h

diff --git a/drivers/i2c/i2c-core-slave.c b/drivers/i2c/i2c-core-slave.c
index 1589179d5eb9..4968a17328b3 100644
--- a/drivers/i2c/i2c-core-slave.c
+++ b/drivers/i2c/i2c-core-slave.c
@@ -14,6 +14,9 @@

#include "i2c-core.h"

+#define CREATE_TRACE_POINTS
+#include <trace/events/i2c_slave.h>
+
int i2c_slave_register(struct i2c_client *client, i2c_slave_cb_t slave_cb)
{
int ret;
@@ -79,6 +82,18 @@ int i2c_slave_unregister(struct i2c_client *client)
}
EXPORT_SYMBOL_GPL(i2c_slave_unregister);

+int i2c_slave_event(struct i2c_client *client,
+ enum i2c_slave_event event, u8 *val)
+{
+ int ret = client->slave_cb(client, event, val);
+
+ if (!ret)
+ trace_i2c_slave(client, event, val);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(i2c_slave_event);
+
/**
* i2c_detect_slave_mode - detect operation mode
* @dev: The device owning the bus
diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index 7d4f52ceb7b5..fbda5ada2afc 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -392,12 +392,8 @@ enum i2c_slave_event {
int i2c_slave_register(struct i2c_client *client, i2c_slave_cb_t slave_cb);
int i2c_slave_unregister(struct i2c_client *client);
bool i2c_detect_slave_mode(struct device *dev);
-
-static inline int i2c_slave_event(struct i2c_client *client,
- enum i2c_slave_event event, u8 *val)
-{
- return client->slave_cb(client, event, val);
-}
+int i2c_slave_event(struct i2c_client *client,
+ enum i2c_slave_event event, u8 *val);
#else
static inline bool i2c_detect_slave_mode(struct device *dev) { return false; }
#endif
diff --git a/include/trace/events/i2c_slave.h b/include/trace/events/i2c_slave.h
new file mode 100644
index 000000000000..1f0c1cfbf2ef
--- /dev/null
+++ b/include/trace/events/i2c_slave.h
@@ -0,0 +1,57 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * I2C slave tracepoints
+ *
+ * Copyright (c) 2022 Qualcomm Innovation Center, Inc. All rights reserved.
+ */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM i2c_slave
+
+#if !defined(_TRACE_I2C_SLAVE_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_I2C_SLAVE_H
+
+#include <linux/i2c.h>
+#include <linux/tracepoint.h>
+
+TRACE_EVENT(i2c_slave,
+ TP_PROTO(const struct i2c_client *client, enum i2c_slave_event event,
+ __u8 *val),
+ TP_ARGS(client, event, val),
+ TP_STRUCT__entry(
+ __field(int, adapter_nr )
+ __field(__u16, addr )
+ __field(enum i2c_slave_event, event )
+ __field(__u16, len )
+ __dynamic_array(__u8, buf, 1) ),
+
+ TP_fast_assign(
+ __entry->adapter_nr = client->adapter->nr;
+ __entry->addr = client->addr;
+ __entry->event = event;
+ switch (event) {
+ case I2C_SLAVE_READ_REQUESTED:
+ case I2C_SLAVE_READ_PROCESSED:
+ case I2C_SLAVE_WRITE_RECEIVED:
+ __entry->len = 1;
+ memcpy(__get_dynamic_array(buf), val, __entry->len);
+ break;
+ default:
+ __entry->len = 0;
+ break;
+ }
+ ),
+ TP_printk("i2c-%d a=%03x %s [%*phD]",
+ __entry->adapter_nr, __entry->addr,
+ __print_symbolic(__entry->event,
+ { I2C_SLAVE_READ_REQUESTED, "RD_REQ" },
+ { I2C_SLAVE_WRITE_REQUESTED, "WR_REQ" },
+ { I2C_SLAVE_READ_PROCESSED, "RD_PRO" },
+ { I2C_SLAVE_WRITE_RECEIVED, "WR_RCV" },
+ { I2C_SLAVE_STOP, " STOP" }),
+ __entry->len, __get_dynamic_array(buf)
+ ));
+
+#endif /* _TRACE_I2C_SLAVE_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>
--
2.25.1
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