| // SPDX-License-Identifier: GPL-2.0 |
| /* |
| * Simple heartbeat STM source driver |
| * Copyright (c) 2016, Intel Corporation. |
| * |
| * Heartbeat STM source will send repetitive messages over STM devices to a |
| * trace host. |
| */ |
| |
| #include <linux/kernel.h> |
| #include <linux/module.h> |
| #include <linux/hrtimer.h> |
| #include <linux/slab.h> |
| #include <linux/stm.h> |
| |
| #define STM_HEARTBEAT_MAX 32 |
| |
| static int nr_devs = 4; |
| static int interval_ms = 10; |
| |
| module_param(nr_devs, int, 0400); |
| module_param(interval_ms, int, 0600); |
| |
| static struct stm_heartbeat { |
| struct stm_source_data data; |
| struct hrtimer hrtimer; |
| unsigned int active; |
| } stm_heartbeat[STM_HEARTBEAT_MAX]; |
| |
| static const char str[] = "heartbeat stm source driver is here to serve you"; |
| |
| static enum hrtimer_restart stm_heartbeat_hrtimer_handler(struct hrtimer *hr) |
| { |
| struct stm_heartbeat *heartbeat = container_of(hr, struct stm_heartbeat, |
| hrtimer); |
| |
| stm_source_write(&heartbeat->data, 0, str, sizeof str); |
| if (heartbeat->active) |
| hrtimer_forward_now(hr, ms_to_ktime(interval_ms)); |
| |
| return heartbeat->active ? HRTIMER_RESTART : HRTIMER_NORESTART; |
| } |
| |
| static int stm_heartbeat_link(struct stm_source_data *data) |
| { |
| struct stm_heartbeat *heartbeat = |
| container_of(data, struct stm_heartbeat, data); |
| |
| heartbeat->active = 1; |
| hrtimer_start(&heartbeat->hrtimer, ms_to_ktime(interval_ms), |
| HRTIMER_MODE_ABS); |
| |
| return 0; |
| } |
| |
| static void stm_heartbeat_unlink(struct stm_source_data *data) |
| { |
| struct stm_heartbeat *heartbeat = |
| container_of(data, struct stm_heartbeat, data); |
| |
| heartbeat->active = 0; |
| hrtimer_cancel(&heartbeat->hrtimer); |
| } |
| |
| static int stm_heartbeat_init(void) |
| { |
| int i, ret = -ENOMEM; |
| |
| if (nr_devs < 0 || nr_devs > STM_HEARTBEAT_MAX) |
| return -EINVAL; |
| |
| for (i = 0; i < nr_devs; i++) { |
| stm_heartbeat[i].data.name = |
| kasprintf(GFP_KERNEL, "heartbeat.%d", i); |
| if (!stm_heartbeat[i].data.name) |
| goto fail_unregister; |
| |
| stm_heartbeat[i].data.nr_chans = 1; |
| stm_heartbeat[i].data.link = stm_heartbeat_link; |
| stm_heartbeat[i].data.unlink = stm_heartbeat_unlink; |
| hrtimer_init(&stm_heartbeat[i].hrtimer, CLOCK_MONOTONIC, |
| HRTIMER_MODE_ABS); |
| stm_heartbeat[i].hrtimer.function = |
| stm_heartbeat_hrtimer_handler; |
| |
| ret = stm_source_register_device(NULL, &stm_heartbeat[i].data); |
| if (ret) |
| goto fail_free; |
| } |
| |
| return 0; |
| |
| fail_unregister: |
| for (i--; i >= 0; i--) { |
| stm_source_unregister_device(&stm_heartbeat[i].data); |
| fail_free: |
| kfree(stm_heartbeat[i].data.name); |
| } |
| |
| return ret; |
| } |
| |
| static void stm_heartbeat_exit(void) |
| { |
| int i; |
| |
| for (i = 0; i < nr_devs; i++) { |
| stm_source_unregister_device(&stm_heartbeat[i].data); |
| kfree(stm_heartbeat[i].data.name); |
| } |
| } |
| |
| module_init(stm_heartbeat_init); |
| module_exit(stm_heartbeat_exit); |
| |
| MODULE_LICENSE("GPL v2"); |
| MODULE_DESCRIPTION("stm_heartbeat driver"); |
| MODULE_AUTHOR("Alexander Shishkin <alexander.shishkin@linux.intel.com>"); |