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1// SPDX-License-Identifier: GPL-2.02/*3 * Simple kernel driver to link kernel Ftrace and an STM device4 * Copyright (c) 2016, Linaro Ltd.5 *6 * STM Ftrace will be registered as a trace_export.7 */8 9#include <linux/module.h>10#include <linux/stm.h>11#include <linux/trace.h>12 13#define STM_FTRACE_NR_CHANNELS 114#define STM_FTRACE_CHAN 015 16static int stm_ftrace_link(struct stm_source_data *data);17static void stm_ftrace_unlink(struct stm_source_data *data);18 19static struct stm_ftrace {20 struct stm_source_data data;21 struct trace_export ftrace;22} stm_ftrace = {23 .data = {24 .name = "ftrace",25 .nr_chans = STM_FTRACE_NR_CHANNELS,26 .type = STM_FTRACE,27 .link = stm_ftrace_link,28 .unlink = stm_ftrace_unlink,29 },30};31 32/**33 * stm_ftrace_write() - write data to STM via 'stm_ftrace' source34 * @buf: buffer containing the data packet35 * @len: length of the data packet36 */37static void notrace38stm_ftrace_write(struct trace_export *export, const void *buf, unsigned int len)39{40 struct stm_ftrace *stm = container_of(export, struct stm_ftrace, ftrace);41 /* This is called from trace system with preemption disabled */42 unsigned int cpu = smp_processor_id();43 44 stm_source_write(&stm->data, STM_FTRACE_CHAN + cpu, buf, len);45}46 47static int stm_ftrace_link(struct stm_source_data *data)48{49 struct stm_ftrace *sf = container_of(data, struct stm_ftrace, data);50 51 sf->ftrace.write = stm_ftrace_write;52 sf->ftrace.flags = TRACE_EXPORT_FUNCTION | TRACE_EXPORT_EVENT53 | TRACE_EXPORT_MARKER;54 55 return register_ftrace_export(&sf->ftrace);56}57 58static void stm_ftrace_unlink(struct stm_source_data *data)59{60 struct stm_ftrace *sf = container_of(data, struct stm_ftrace, data);61 62 unregister_ftrace_export(&sf->ftrace);63}64 65static int __init stm_ftrace_init(void)66{67 int ret;68 69 stm_ftrace.data.nr_chans = roundup_pow_of_two(num_possible_cpus());70 ret = stm_source_register_device(NULL, &stm_ftrace.data);71 if (ret)72 pr_err("Failed to register stm_source - ftrace.\n");73 74 return ret;75}76 77static void __exit stm_ftrace_exit(void)78{79 stm_source_unregister_device(&stm_ftrace.data);80}81 82module_init(stm_ftrace_init);83module_exit(stm_ftrace_exit);84 85MODULE_LICENSE("GPL v2");86MODULE_DESCRIPTION("stm_ftrace driver");87MODULE_AUTHOR("Chunyan Zhang <zhang.chunyan@linaro.org>");88