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Date: Fri, 18 Mar 2022 10:02:49 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: Jae Hyun Yoo <quic_jaehyoo@...cinc.com>
Cc: Wolfram Sang <wsa@...nel.org>, "Ingo Molnar" <mingo@...hat.com>,
Jamie Iles <quic_jiles@...cinc.com>,
Graeme Gregory <quic_ggregory@...cinc.com>,
<linux-kernel@...r.kernel.org>, <linux-i2c@...r.kernel.org>
Subject: Re: [PATCH v2] i2c: add tracepoints for I2C slave events
On Tue, 8 Mar 2022 08:33:33 -0800
Jae Hyun Yoo <quic_jaehyoo@...cinc.com> wrote:
> 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@...cinc.com>
> ---
> Changes v1 -> v2:
> * Fixed trace_2c_slave call condition to optimize conditional compare logic
> (Steven)
> * Fixed TP entry order to prevent wasting spaces in the ring buffer (Steven)
> * Replaced __get_dynamic_array with __array for storing 1-length data value
> to make it faster and save space (Steven)
>
> 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..4299de933ac6 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 (trace_i2c_slave_enabled() && !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..3aaf5fb76796
> --- /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(__u16, len )
> + __field(enum i2c_slave_event, event )
> + __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(__entry->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" }),
For the above to be useful for perf and trace-cmd (user space tools) you
will need to export them with:
TRACE_DEFINE_ENUM(I2C_SLAVE_READ_REQUESTED);
TRACE_DEFINE_ENUM(I2C_SLAVE_WRITE_REQUESTED);
TRACE_DEFINE_ENUM(I2C_SLAVE_READ_PROCESSED);
TRACE_DEFINE_ENUM(I2C_SLAVE_WRITE_PROCESSED);
TRACE_DEFINE_ENUM(I2C_SLAVE_STOP);
before the TRACE_EVENT()
-- Steve
> + __entry->len, __entry->buf
> + ));
> +
> +#endif /* _TRACE_I2C_SLAVE_H */
> +
> +/* This part must be outside protection */
> +#include <trace/define_trace.h>
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