// 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); stm_source_write(&stm->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>");