// SPDX-License-Identifier: GPL-2.0
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/*
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* Simple kernel driver to link kernel Ftrace and an STM device
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* Copyright (c) 2016, Linaro Ltd.
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*
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* STM Ftrace will be registered as a trace_export.
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*/
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#include <linux/module.h>
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#include <linux/stm.h>
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#include <linux/trace.h>
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#define STM_FTRACE_NR_CHANNELS 1
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#define STM_FTRACE_CHAN 0
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static int stm_ftrace_link(struct stm_source_data *data);
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static void stm_ftrace_unlink(struct stm_source_data *data);
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static struct stm_ftrace {
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struct stm_source_data data;
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struct trace_export ftrace;
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} stm_ftrace = {
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.data = {
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.name = "ftrace",
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.nr_chans = STM_FTRACE_NR_CHANNELS,
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.link = stm_ftrace_link,
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.unlink = stm_ftrace_unlink,
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},
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};
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/**
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* stm_ftrace_write() - write data to STM via 'stm_ftrace' source
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* @buf: buffer containing the data packet
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* @len: length of the data packet
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*/
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static void notrace
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stm_ftrace_write(struct trace_export *export, const void *buf, unsigned int len)
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{
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struct stm_ftrace *stm = container_of(export, struct stm_ftrace, ftrace);
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/* This is called from trace system with preemption disabled */
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unsigned int cpu = smp_processor_id();
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stm_source_write(&stm->data, STM_FTRACE_CHAN + cpu, buf, len);
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}
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static int stm_ftrace_link(struct stm_source_data *data)
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{
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struct stm_ftrace *sf = container_of(data, struct stm_ftrace, data);
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sf->ftrace.write = stm_ftrace_write;
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sf->ftrace.flags = TRACE_EXPORT_FUNCTION | TRACE_EXPORT_EVENT
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| TRACE_EXPORT_MARKER;
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return register_ftrace_export(&sf->ftrace);
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}
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static void stm_ftrace_unlink(struct stm_source_data *data)
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{
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struct stm_ftrace *sf = container_of(data, struct stm_ftrace, data);
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unregister_ftrace_export(&sf->ftrace);
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}
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static int __init stm_ftrace_init(void)
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{
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int ret;
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stm_ftrace.data.nr_chans = roundup_pow_of_two(num_possible_cpus());
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ret = stm_source_register_device(NULL, &stm_ftrace.data);
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if (ret)
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pr_err("Failed to register stm_source - ftrace.\n");
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return ret;
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}
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static void __exit stm_ftrace_exit(void)
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{
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stm_source_unregister_device(&stm_ftrace.data);
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}
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module_init(stm_ftrace_init);
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module_exit(stm_ftrace_exit);
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MODULE_LICENSE("GPL v2");
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MODULE_DESCRIPTION("stm_ftrace driver");
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MODULE_AUTHOR("Chunyan Zhang <zhang.chunyan@linaro.org>");
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