1ad0dfdfdSMathieu Poirier // SPDX-License-Identifier: GPL-2.0 2262e1f6eSChunyan Zhang /* 3262e1f6eSChunyan Zhang * Simple kernel driver to link kernel Ftrace and an STM device 4262e1f6eSChunyan Zhang * Copyright (c) 2016, Linaro Ltd. 5262e1f6eSChunyan Zhang * 6262e1f6eSChunyan Zhang * STM Ftrace will be registered as a trace_export. 7262e1f6eSChunyan Zhang */ 8262e1f6eSChunyan Zhang 9262e1f6eSChunyan Zhang #include <linux/module.h> 10262e1f6eSChunyan Zhang #include <linux/stm.h> 11262e1f6eSChunyan Zhang #include <linux/trace.h> 12262e1f6eSChunyan Zhang 13262e1f6eSChunyan Zhang #define STM_FTRACE_NR_CHANNELS 1 14262e1f6eSChunyan Zhang #define STM_FTRACE_CHAN 0 15262e1f6eSChunyan Zhang 16262e1f6eSChunyan Zhang static int stm_ftrace_link(struct stm_source_data *data); 17262e1f6eSChunyan Zhang static void stm_ftrace_unlink(struct stm_source_data *data); 18262e1f6eSChunyan Zhang 19262e1f6eSChunyan Zhang static struct stm_ftrace { 20262e1f6eSChunyan Zhang struct stm_source_data data; 21262e1f6eSChunyan Zhang struct trace_export ftrace; 22262e1f6eSChunyan Zhang } stm_ftrace = { 23262e1f6eSChunyan Zhang .data = { 24262e1f6eSChunyan Zhang .name = "ftrace", 25262e1f6eSChunyan Zhang .nr_chans = STM_FTRACE_NR_CHANNELS, 26*07cf8356SMikhail Lappo .type = STM_FTRACE, 27262e1f6eSChunyan Zhang .link = stm_ftrace_link, 28262e1f6eSChunyan Zhang .unlink = stm_ftrace_unlink, 29262e1f6eSChunyan Zhang }, 30262e1f6eSChunyan Zhang }; 31262e1f6eSChunyan Zhang 32262e1f6eSChunyan Zhang /** 33262e1f6eSChunyan Zhang * stm_ftrace_write() - write data to STM via 'stm_ftrace' source 34262e1f6eSChunyan Zhang * @buf: buffer containing the data packet 35262e1f6eSChunyan Zhang * @len: length of the data packet 36262e1f6eSChunyan Zhang */ 37262e1f6eSChunyan Zhang static void notrace 38a773d419SFelipe Balbi stm_ftrace_write(struct trace_export *export, const void *buf, unsigned int len) 39262e1f6eSChunyan Zhang { 40a773d419SFelipe Balbi struct stm_ftrace *stm = container_of(export, struct stm_ftrace, ftrace); 41b8f8534bSTingwei Zhang /* This is called from trace system with preemption disabled */ 42b8f8534bSTingwei Zhang unsigned int cpu = smp_processor_id(); 43a773d419SFelipe Balbi 44b8f8534bSTingwei Zhang stm_source_write(&stm->data, STM_FTRACE_CHAN + cpu, buf, len); 45262e1f6eSChunyan Zhang } 46262e1f6eSChunyan Zhang 47262e1f6eSChunyan Zhang static int stm_ftrace_link(struct stm_source_data *data) 48262e1f6eSChunyan Zhang { 49262e1f6eSChunyan Zhang struct stm_ftrace *sf = container_of(data, struct stm_ftrace, data); 50262e1f6eSChunyan Zhang 51262e1f6eSChunyan Zhang sf->ftrace.write = stm_ftrace_write; 52e8ecea30STingwei Zhang sf->ftrace.flags = TRACE_EXPORT_FUNCTION | TRACE_EXPORT_EVENT 53e8ecea30STingwei Zhang | TRACE_EXPORT_MARKER; 54262e1f6eSChunyan Zhang 55262e1f6eSChunyan Zhang return register_ftrace_export(&sf->ftrace); 56262e1f6eSChunyan Zhang } 57262e1f6eSChunyan Zhang 58262e1f6eSChunyan Zhang static void stm_ftrace_unlink(struct stm_source_data *data) 59262e1f6eSChunyan Zhang { 60262e1f6eSChunyan Zhang struct stm_ftrace *sf = container_of(data, struct stm_ftrace, data); 61262e1f6eSChunyan Zhang 62262e1f6eSChunyan Zhang unregister_ftrace_export(&sf->ftrace); 63262e1f6eSChunyan Zhang } 64262e1f6eSChunyan Zhang 65262e1f6eSChunyan Zhang static int __init stm_ftrace_init(void) 66262e1f6eSChunyan Zhang { 67262e1f6eSChunyan Zhang int ret; 68262e1f6eSChunyan Zhang 69b8f8534bSTingwei Zhang stm_ftrace.data.nr_chans = roundup_pow_of_two(num_possible_cpus()); 70262e1f6eSChunyan Zhang ret = stm_source_register_device(NULL, &stm_ftrace.data); 71262e1f6eSChunyan Zhang if (ret) 72262e1f6eSChunyan Zhang pr_err("Failed to register stm_source - ftrace.\n"); 73262e1f6eSChunyan Zhang 74262e1f6eSChunyan Zhang return ret; 75262e1f6eSChunyan Zhang } 76262e1f6eSChunyan Zhang 77262e1f6eSChunyan Zhang static void __exit stm_ftrace_exit(void) 78262e1f6eSChunyan Zhang { 79262e1f6eSChunyan Zhang stm_source_unregister_device(&stm_ftrace.data); 80262e1f6eSChunyan Zhang } 81262e1f6eSChunyan Zhang 82262e1f6eSChunyan Zhang module_init(stm_ftrace_init); 83262e1f6eSChunyan Zhang module_exit(stm_ftrace_exit); 84262e1f6eSChunyan Zhang 85262e1f6eSChunyan Zhang MODULE_LICENSE("GPL v2"); 86262e1f6eSChunyan Zhang MODULE_DESCRIPTION("stm_ftrace driver"); 87262e1f6eSChunyan Zhang MODULE_AUTHOR("Chunyan Zhang <zhang.chunyan@linaro.org>"); 88