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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * Copyright 2016 Jonathan Cameron <jic23@kernel.org>4 *5 * Based on a mashup of the hrtimer trigger and continuous sampling proposal of6 * Gregor Boirie <gregor.boirie@parrot.com>7 *8 * Note this is still rather experimental and may eat babies.9 *10 * Todo11 * * Protect against connection of devices that 'need' the top half12 * handler.13 * * Work out how to run top half handlers in this context if it is14 * safe to do so (timestamp grabbing for example)15 *16 * Tested against a max1363. Used about 33% cpu for the thread and 20%17 * for generic_buffer piping to /dev/null. Watermark set at 64 on a 12818 * element kfifo buffer.19 */20 21#include <linux/kernel.h>22#include <linux/module.h>23#include <linux/platform_device.h>24#include <linux/slab.h>25#include <linux/irq_work.h>26#include <linux/kthread.h>27#include <linux/freezer.h>28 29#include <linux/iio/iio.h>30#include <linux/iio/trigger.h>31#include <linux/iio/sw_trigger.h>32 33struct iio_loop_info {34 struct iio_sw_trigger swt;35 struct task_struct *task;36};37 38static const struct config_item_type iio_loop_type = {39 .ct_owner = THIS_MODULE,40};41 42static int iio_loop_thread(void *data)43{44 struct iio_trigger *trig = data;45 46 set_freezable();47 48 do {49 iio_trigger_poll_nested(trig);50 } while (likely(!kthread_freezable_should_stop(NULL)));51 52 return 0;53}54 55static int iio_loop_trigger_set_state(struct iio_trigger *trig, bool state)56{57 struct iio_loop_info *loop_trig = iio_trigger_get_drvdata(trig);58 59 if (state) {60 loop_trig->task = kthread_run(iio_loop_thread,61 trig, trig->name);62 if (IS_ERR(loop_trig->task)) {63 dev_err(&trig->dev,64 "failed to create trigger loop thread\n");65 return PTR_ERR(loop_trig->task);66 }67 } else {68 kthread_stop(loop_trig->task);69 }70 71 return 0;72}73 74static const struct iio_trigger_ops iio_loop_trigger_ops = {75 .set_trigger_state = iio_loop_trigger_set_state,76};77 78static struct iio_sw_trigger *iio_trig_loop_probe(const char *name)79{80 struct iio_loop_info *trig_info;81 int ret;82 83 trig_info = kzalloc(sizeof(*trig_info), GFP_KERNEL);84 if (!trig_info)85 return ERR_PTR(-ENOMEM);86 87 trig_info->swt.trigger = iio_trigger_alloc(NULL, "%s", name);88 if (!trig_info->swt.trigger) {89 ret = -ENOMEM;90 goto err_free_trig_info;91 }92 93 iio_trigger_set_drvdata(trig_info->swt.trigger, trig_info);94 trig_info->swt.trigger->ops = &iio_loop_trigger_ops;95 96 ret = iio_trigger_register(trig_info->swt.trigger);97 if (ret)98 goto err_free_trigger;99 100 iio_swt_group_init_type_name(&trig_info->swt, name, &iio_loop_type);101 102 return &trig_info->swt;103 104err_free_trigger:105 iio_trigger_free(trig_info->swt.trigger);106err_free_trig_info:107 kfree(trig_info);108 109 return ERR_PTR(ret);110}111 112static int iio_trig_loop_remove(struct iio_sw_trigger *swt)113{114 struct iio_loop_info *trig_info;115 116 trig_info = iio_trigger_get_drvdata(swt->trigger);117 118 iio_trigger_unregister(swt->trigger);119 iio_trigger_free(swt->trigger);120 kfree(trig_info);121 122 return 0;123}124 125static const struct iio_sw_trigger_ops iio_trig_loop_ops = {126 .probe = iio_trig_loop_probe,127 .remove = iio_trig_loop_remove,128};129 130static struct iio_sw_trigger_type iio_trig_loop = {131 .name = "loop",132 .owner = THIS_MODULE,133 .ops = &iio_trig_loop_ops,134};135 136module_iio_sw_trigger_driver(iio_trig_loop);137 138MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>");139MODULE_DESCRIPTION("Loop based trigger for the iio subsystem");140MODULE_LICENSE("GPL v2");141MODULE_ALIAS("platform:iio-trig-loop");142