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Commit 262e1f6e authored by Chunyan Zhang's avatar Chunyan Zhang Committed by Steven Rostedt
Browse files

stm class: ftrace: Add ftrace-export-over-stm driver 

This patch adds a driver that models itself as an stm_source called
stm_ftrace. Once the stm device and stm_ftrace have been linked via
sysfs, the driver registers itself as a trace_export and everything
passed to the interface from Ftrace subsystem will end up in the STM
trace engine.

Link: http://lkml.kernel.org/r/1479715043-6534-3-git-send-email-zhang.chunyan@linaro.org



Signed-off-by: default avatarChunyan Zhang <zhang.chunyan@linaro.org>
Acked-by: default avatarAlexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
parent 478409dd

drivers/hwtracing/stm/Kconfig

+11 −0
Original line number Diff line number Diff line
@@ -39,4 +39,15 @@ config STM_SOURCE_HEARTBEAT 
	  If you want to send heartbeat messages over STM devices,

	  say Y.



config STM_SOURCE_FTRACE

	tristate "Copy the output from kernel Ftrace to STM engine"

	depends on FUNCTION_TRACER

	help

	  This option can be used to copy the output from kernel Ftrace

	  to STM engine. Enabling this option will introduce a slight

	  timing effect.



	  If you want to send kernel Ftrace messages over STM devices,

	  say Y.



endif

drivers/hwtracing/stm/Makefile

+2 −0
Original line number Diff line number Diff line
@@ -6,6 +6,8 @@ obj-$(CONFIG_STM_DUMMY) += dummy_stm.o 


obj-$(CONFIG_STM_SOURCE_CONSOLE)	+= stm_console.o

obj-$(CONFIG_STM_SOURCE_HEARTBEAT)	+= stm_heartbeat.o

obj-$(CONFIG_STM_SOURCE_FTRACE)		+= stm_ftrace.o



stm_console-y		:= console.o

stm_heartbeat-y		:= heartbeat.o

stm_ftrace-y		:= ftrace.o

drivers/hwtracing/stm/ftrace.c

0 → 100644
+87 −0
Original line number Diff line number Diff line 
/*

 * Simple kernel driver to link kernel Ftrace and an STM device

 * Copyright (c) 2016, Linaro Ltd.

 *

 * This program is free software; you can redistribute it and/or modify it

 * under the terms and conditions of the GNU General Public License,

 * version 2, as published by the Free Software Foundation.

 *

 * This program is distributed in the hope it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for

 * more details.

 *

 * STM Ftrace will be registered as a trace_export.

 */



#include <linux/module.h>

#include <linux/stm.h>

#include <linux/trace.h>



#define STM_FTRACE_NR_CHANNELS 1

#define STM_FTRACE_CHAN 0



static int stm_ftrace_link(struct stm_source_data *data);

static void stm_ftrace_unlink(struct stm_source_data *data);



static struct stm_ftrace {

	struct stm_source_data	data;

	struct trace_export	ftrace;

} stm_ftrace = {

	.data	= {

		.name		= "ftrace",

		.nr_chans	= STM_FTRACE_NR_CHANNELS,

		.link		= stm_ftrace_link,

		.unlink		= stm_ftrace_unlink,

	},

};



/**

 * stm_ftrace_write() - write data to STM via 'stm_ftrace' source

 * @buf:	buffer containing the data packet

 * @len:	length of the data packet

 */

static void notrace

stm_ftrace_write(const void *buf, unsigned int len)

{

	stm_source_write(&stm_ftrace.data, STM_FTRACE_CHAN, buf, len);

}



static int stm_ftrace_link(struct stm_source_data *data)

{

	struct stm_ftrace *sf = container_of(data, struct stm_ftrace, data);



	sf->ftrace.write = stm_ftrace_write;



	return register_ftrace_export(&sf->ftrace);

}



static void stm_ftrace_unlink(struct stm_source_data *data)

{

	struct stm_ftrace *sf = container_of(data, struct stm_ftrace, data);



	unregister_ftrace_export(&sf->ftrace);

}



static int __init stm_ftrace_init(void)

{

	int ret;



	ret = stm_source_register_device(NULL, &stm_ftrace.data);

	if (ret)

		pr_err("Failed to register stm_source - ftrace.\n");



	return ret;

}



static void __exit stm_ftrace_exit(void)

{

	stm_source_unregister_device(&stm_ftrace.data);

}



module_init(stm_ftrace_init);

module_exit(stm_ftrace_exit);



MODULE_LICENSE("GPL v2");

MODULE_DESCRIPTION("stm_ftrace driver");

MODULE_AUTHOR("Chunyan Zhang <zhang.chunyan@linaro.org>");