tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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
24static int stm_ftrace_link(struct stm_source_data *data);
25static void stm_ftrace_unlink(struct stm_source_data *data);
26
27static 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 */
44static void notrace
45stm_ftrace_write(struct trace_export *export, const void *buf, unsigned int len)
46{
47 struct stm_ftrace *stm = container_of(export, struct stm_ftrace, ftrace);
48
49 stm_source_write(&stm->data, STM_FTRACE_CHAN, buf, len);
50}
51
52static int stm_ftrace_link(struct stm_source_data *data)
53{
54 struct stm_ftrace *sf = container_of(data, struct stm_ftrace, data);
55
56 sf->ftrace.write = stm_ftrace_write;
57
58 return register_ftrace_export(&sf->ftrace);
59}
60
61static void stm_ftrace_unlink(struct stm_source_data *data)
62{
63 struct stm_ftrace *sf = container_of(data, struct stm_ftrace, data);
64
65 unregister_ftrace_export(&sf->ftrace);
66}
67
68static int __init stm_ftrace_init(void)
69{
70 int ret;
71
72 ret = stm_source_register_device(NULL, &stm_ftrace.data);
73 if (ret)
74 pr_err("Failed to register stm_source - ftrace.\n");
75
76 return ret;
77}
78
79static void __exit stm_ftrace_exit(void)
80{
81 stm_source_unregister_device(&stm_ftrace.data);
82}
83
84module_init(stm_ftrace_init);
85module_exit(stm_ftrace_exit);
86
87MODULE_LICENSE("GPL v2");
88MODULE_DESCRIPTION("stm_ftrace driver");
89MODULE_AUTHOR("Chunyan Zhang <zhang.chunyan@linaro.org>");