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// SPDX-License-Identifier: GPL-2.0
/*
* Simple kernel driver to link kernel Ftrace and an STM device
* Copyright (c) 2016, Linaro Ltd.
*
* 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(struct trace_export *export, const void *buf, unsigned int len)
{
struct stm_ftrace *stm = container_of(export, struct stm_ftrace, ftrace);
/* This is called from trace system with preemption disabled */
unsigned int cpu = smp_processor_id();
stm_source_write(&stm->data, STM_FTRACE_CHAN + cpu, 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;
sf->ftrace.flags = TRACE_EXPORT_FUNCTION | TRACE_EXPORT_EVENT
| TRACE_EXPORT_MARKER;
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;
stm_ftrace.data.nr_chans = roundup_pow_of_two(num_possible_cpus());
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>");
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