OpenE2K
/
linux
6
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

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: Chunyan Zhang <zhang.chunyan@linaro.org>
Acked-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Chunyan Zhang 2016-11-21 15:57:19 +08:00 committed by Steven Rostedt
parent 478409dd68
commit 262e1f6e39
3 changed files with 100 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
drivers/hwtracing/stm/Kconfig
View File

@ -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

2
drivers/hwtracing/stm/Makefile
View File

@ -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

87
drivers/hwtracing/stm/ftrace.c Normal file
View File

@ -0,0 +1,87 @@
/*
* 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>");