1 /* 2 * Simple kernel driver to link kernel Ftrace and an STM device 3 * Copyright (c) 2016, Linaro Ltd. 4 * 5 * This program is free software; you can redistribute it and/or modify it 6 * under the terms and conditions of the GNU General Public License, 7 * version 2, as published by the Free Software Foundation. 8 * 9 * This program is distributed in the hope it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for 12 * more details. 13 * 14 * STM Ftrace will be registered as a trace_export. 15 */ 16 17 #include <linux/module.h> 18 #include <linux/stm.h> 19 #include <linux/trace.h> 20 21 #define STM_FTRACE_NR_CHANNELS 1 22 #define STM_FTRACE_CHAN 0 23 24 static int stm_ftrace_link(struct stm_source_data *data); 25 static void stm_ftrace_unlink(struct stm_source_data *data); 26 27 static struct stm_ftrace { 28 struct stm_source_data data; 29 struct trace_export ftrace; 30 } stm_ftrace = { 31 .data = { 32 .name = "ftrace", 33 .nr_chans = STM_FTRACE_NR_CHANNELS, 34 .link = stm_ftrace_link, 35 .unlink = stm_ftrace_unlink, 36 }, 37 }; 38 39 /** 40 * stm_ftrace_write() - write data to STM via 'stm_ftrace' source 41 * @buf: buffer containing the data packet 42 * @len: length of the data packet 43 */ 44 static void notrace 45 stm_ftrace_write(const void *buf, unsigned int len) 46 { 47 stm_source_write(&stm_ftrace.data, STM_FTRACE_CHAN, buf, len); 48 } 49 50 static int stm_ftrace_link(struct stm_source_data *data) 51 { 52 struct stm_ftrace *sf = container_of(data, struct stm_ftrace, data); 53 54 sf->ftrace.write = stm_ftrace_write; 55 56 return register_ftrace_export(&sf->ftrace); 57 } 58 59 static void stm_ftrace_unlink(struct stm_source_data *data) 60 { 61 struct stm_ftrace *sf = container_of(data, struct stm_ftrace, data); 62 63 unregister_ftrace_export(&sf->ftrace); 64 } 65 66 static int __init stm_ftrace_init(void) 67 { 68 int ret; 69 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 77 static void __exit stm_ftrace_exit(void) 78 { 79 stm_source_unregister_device(&stm_ftrace.data); 80 } 81 82 module_init(stm_ftrace_init); 83 module_exit(stm_ftrace_exit); 84 85 MODULE_LICENSE("GPL v2"); 86 MODULE_DESCRIPTION("stm_ftrace driver"); 87 MODULE_AUTHOR("Chunyan Zhang <zhang.chunyan@linaro.org>"); 88