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1// SPDX-License-Identifier: GPL-2.02/*3 * Simple heartbeat STM source driver4 * Copyright (c) 2016, Intel Corporation.5 *6 * Heartbeat STM source will send repetitive messages over STM devices to a7 * trace host.8 */9 10#include <linux/kernel.h>11#include <linux/module.h>12#include <linux/hrtimer.h>13#include <linux/slab.h>14#include <linux/stm.h>15 16#define STM_HEARTBEAT_MAX 3217 18static int nr_devs = 4;19static int interval_ms = 10;20 21module_param(nr_devs, int, 0400);22module_param(interval_ms, int, 0600);23 24static struct stm_heartbeat {25 struct stm_source_data data;26 struct hrtimer hrtimer;27 unsigned int active;28} stm_heartbeat[STM_HEARTBEAT_MAX];29 30static const char str[] = "heartbeat stm source driver is here to serve you";31 32static enum hrtimer_restart stm_heartbeat_hrtimer_handler(struct hrtimer *hr)33{34 struct stm_heartbeat *heartbeat = container_of(hr, struct stm_heartbeat,35 hrtimer);36 37 stm_source_write(&heartbeat->data, 0, str, sizeof str);38 if (heartbeat->active)39 hrtimer_forward_now(hr, ms_to_ktime(interval_ms));40 41 return heartbeat->active ? HRTIMER_RESTART : HRTIMER_NORESTART;42}43 44static int stm_heartbeat_link(struct stm_source_data *data)45{46 struct stm_heartbeat *heartbeat =47 container_of(data, struct stm_heartbeat, data);48 49 heartbeat->active = 1;50 hrtimer_start(&heartbeat->hrtimer, ms_to_ktime(interval_ms),51 HRTIMER_MODE_ABS);52 53 return 0;54}55 56static void stm_heartbeat_unlink(struct stm_source_data *data)57{58 struct stm_heartbeat *heartbeat =59 container_of(data, struct stm_heartbeat, data);60 61 heartbeat->active = 0;62 hrtimer_cancel(&heartbeat->hrtimer);63}64 65static int stm_heartbeat_init(void)66{67 int i, ret;68 69 if (nr_devs < 0 || nr_devs > STM_HEARTBEAT_MAX)70 return -EINVAL;71 72 for (i = 0; i < nr_devs; i++) {73 stm_heartbeat[i].data.name =74 kasprintf(GFP_KERNEL, "heartbeat.%d", i);75 if (!stm_heartbeat[i].data.name) {76 ret = -ENOMEM;77 goto fail_unregister;78 }79 80 stm_heartbeat[i].data.nr_chans = 1;81 stm_heartbeat[i].data.type = STM_USER;82 stm_heartbeat[i].data.link = stm_heartbeat_link;83 stm_heartbeat[i].data.unlink = stm_heartbeat_unlink;84 hrtimer_init(&stm_heartbeat[i].hrtimer, CLOCK_MONOTONIC,85 HRTIMER_MODE_ABS);86 stm_heartbeat[i].hrtimer.function =87 stm_heartbeat_hrtimer_handler;88 89 ret = stm_source_register_device(NULL, &stm_heartbeat[i].data);90 if (ret)91 goto fail_free;92 }93 94 return 0;95 96fail_unregister:97 for (i--; i >= 0; i--) {98 stm_source_unregister_device(&stm_heartbeat[i].data);99fail_free:100 kfree(stm_heartbeat[i].data.name);101 }102 103 return ret;104}105 106static void stm_heartbeat_exit(void)107{108 int i;109 110 for (i = 0; i < nr_devs; i++) {111 stm_source_unregister_device(&stm_heartbeat[i].data);112 kfree(stm_heartbeat[i].data.name);113 }114}115 116module_init(stm_heartbeat_init);117module_exit(stm_heartbeat_exit);118 119MODULE_LICENSE("GPL v2");120MODULE_DESCRIPTION("stm_heartbeat driver");121MODULE_AUTHOR("Alexander Shishkin <alexander.shishkin@linux.intel.com>");122