127 lines
3.2 KiB
C
127 lines
3.2 KiB
C
/*
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* Simple heartbeat STM source driver
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* Copyright (c) 2016, Intel Corporation.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms and conditions of the GNU General Public License,
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* version 2, as published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* Heartbeat STM source will send repetitive messages over STM devices to a
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* trace host.
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/hrtimer.h>
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#include <linux/slab.h>
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#include <linux/stm.h>
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#define STM_HEARTBEAT_MAX 32
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static int nr_devs = 4;
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static int interval_ms = 10;
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module_param(nr_devs, int, 0400);
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module_param(interval_ms, int, 0600);
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static struct stm_heartbeat {
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struct stm_source_data data;
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struct hrtimer hrtimer;
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unsigned int active;
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} stm_heartbeat[STM_HEARTBEAT_MAX];
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static const char str[] = "heartbeat stm source driver is here to serve you";
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static enum hrtimer_restart stm_heartbeat_hrtimer_handler(struct hrtimer *hr)
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{
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struct stm_heartbeat *heartbeat = container_of(hr, struct stm_heartbeat,
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hrtimer);
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stm_source_write(&heartbeat->data, 0, str, sizeof str);
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if (heartbeat->active)
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hrtimer_forward_now(hr, ms_to_ktime(interval_ms));
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return heartbeat->active ? HRTIMER_RESTART : HRTIMER_NORESTART;
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}
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static int stm_heartbeat_link(struct stm_source_data *data)
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{
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struct stm_heartbeat *heartbeat =
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container_of(data, struct stm_heartbeat, data);
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heartbeat->active = 1;
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hrtimer_start(&heartbeat->hrtimer, ms_to_ktime(interval_ms),
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HRTIMER_MODE_ABS);
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return 0;
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}
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static void stm_heartbeat_unlink(struct stm_source_data *data)
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{
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struct stm_heartbeat *heartbeat =
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container_of(data, struct stm_heartbeat, data);
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heartbeat->active = 0;
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hrtimer_cancel(&heartbeat->hrtimer);
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}
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static int stm_heartbeat_init(void)
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{
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int i, ret = -ENOMEM;
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if (nr_devs < 0 || nr_devs > STM_HEARTBEAT_MAX)
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return -EINVAL;
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for (i = 0; i < nr_devs; i++) {
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stm_heartbeat[i].data.name =
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kasprintf(GFP_KERNEL, "heartbeat.%d", i);
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if (!stm_heartbeat[i].data.name)
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goto fail_unregister;
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stm_heartbeat[i].data.nr_chans = 1;
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stm_heartbeat[i].data.link = stm_heartbeat_link;
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stm_heartbeat[i].data.unlink = stm_heartbeat_unlink;
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hrtimer_init(&stm_heartbeat[i].hrtimer, CLOCK_MONOTONIC,
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HRTIMER_MODE_ABS);
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stm_heartbeat[i].hrtimer.function =
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stm_heartbeat_hrtimer_handler;
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ret = stm_source_register_device(NULL, &stm_heartbeat[i].data);
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if (ret)
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goto fail_free;
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}
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return 0;
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fail_unregister:
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for (i--; i >= 0; i--) {
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stm_source_unregister_device(&stm_heartbeat[i].data);
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fail_free:
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kfree(stm_heartbeat[i].data.name);
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}
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return ret;
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}
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static void stm_heartbeat_exit(void)
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{
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int i;
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for (i = 0; i < nr_devs; i++) {
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stm_source_unregister_device(&stm_heartbeat[i].data);
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kfree(stm_heartbeat[i].data.name);
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}
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}
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module_init(stm_heartbeat_init);
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module_exit(stm_heartbeat_exit);
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MODULE_LICENSE("GPL v2");
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MODULE_DESCRIPTION("stm_heartbeat driver");
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MODULE_AUTHOR("Alexander Shishkin <alexander.shishkin@linux.intel.com>");
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