Linux 4.16.11
[linux/fpc-iii.git] / drivers / hwtracing / stm / heartbeat.c
blob3da7b673aab252a245991c901eb5a07696c5fb38
1 /*
2 * Simple heartbeat STM source driver
3 * Copyright (c) 2016, Intel Corporation.
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.
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.
14 * Heartbeat STM source will send repetitive messages over STM devices to a
15 * trace host.
18 #include <linux/kernel.h>
19 #include <linux/module.h>
20 #include <linux/hrtimer.h>
21 #include <linux/slab.h>
22 #include <linux/stm.h>
24 #define STM_HEARTBEAT_MAX 32
26 static int nr_devs = 4;
27 static int interval_ms = 10;
29 module_param(nr_devs, int, 0400);
30 module_param(interval_ms, int, 0600);
32 static struct stm_heartbeat {
33 struct stm_source_data data;
34 struct hrtimer hrtimer;
35 unsigned int active;
36 } stm_heartbeat[STM_HEARTBEAT_MAX];
38 static const char str[] = "heartbeat stm source driver is here to serve you";
40 static enum hrtimer_restart stm_heartbeat_hrtimer_handler(struct hrtimer *hr)
42 struct stm_heartbeat *heartbeat = container_of(hr, struct stm_heartbeat,
43 hrtimer);
45 stm_source_write(&heartbeat->data, 0, str, sizeof str);
46 if (heartbeat->active)
47 hrtimer_forward_now(hr, ms_to_ktime(interval_ms));
49 return heartbeat->active ? HRTIMER_RESTART : HRTIMER_NORESTART;
52 static int stm_heartbeat_link(struct stm_source_data *data)
54 struct stm_heartbeat *heartbeat =
55 container_of(data, struct stm_heartbeat, data);
57 heartbeat->active = 1;
58 hrtimer_start(&heartbeat->hrtimer, ms_to_ktime(interval_ms),
59 HRTIMER_MODE_ABS);
61 return 0;
64 static void stm_heartbeat_unlink(struct stm_source_data *data)
66 struct stm_heartbeat *heartbeat =
67 container_of(data, struct stm_heartbeat, data);
69 heartbeat->active = 0;
70 hrtimer_cancel(&heartbeat->hrtimer);
73 static int stm_heartbeat_init(void)
75 int i, ret = -ENOMEM;
77 if (nr_devs < 0 || nr_devs > STM_HEARTBEAT_MAX)
78 return -EINVAL;
80 for (i = 0; i < nr_devs; i++) {
81 stm_heartbeat[i].data.name =
82 kasprintf(GFP_KERNEL, "heartbeat.%d", i);
83 if (!stm_heartbeat[i].data.name)
84 goto fail_unregister;
86 stm_heartbeat[i].data.nr_chans = 1;
87 stm_heartbeat[i].data.link = stm_heartbeat_link;
88 stm_heartbeat[i].data.unlink = stm_heartbeat_unlink;
89 hrtimer_init(&stm_heartbeat[i].hrtimer, CLOCK_MONOTONIC,
90 HRTIMER_MODE_ABS);
91 stm_heartbeat[i].hrtimer.function =
92 stm_heartbeat_hrtimer_handler;
94 ret = stm_source_register_device(NULL, &stm_heartbeat[i].data);
95 if (ret)
96 goto fail_free;
99 return 0;
101 fail_unregister:
102 for (i--; i >= 0; i--) {
103 stm_source_unregister_device(&stm_heartbeat[i].data);
104 fail_free:
105 kfree(stm_heartbeat[i].data.name);
108 return ret;
111 static void stm_heartbeat_exit(void)
113 int i;
115 for (i = 0; i < nr_devs; i++) {
116 stm_source_unregister_device(&stm_heartbeat[i].data);
117 kfree(stm_heartbeat[i].data.name);
121 module_init(stm_heartbeat_init);
122 module_exit(stm_heartbeat_exit);
124 MODULE_LICENSE("GPL v2");
125 MODULE_DESCRIPTION("stm_heartbeat driver");
126 MODULE_AUTHOR("Alexander Shishkin <alexander.shishkin@linux.intel.com>");