linux-imx

/*

 * Copyright 2016 Jonathan Cameron <jic23@kernel.org>

 *

 * Licensed under the GPL-2.

 *

 * Based on a mashup of the hrtimer trigger and continuous sampling proposal of

 * Gregor Boirie <gregor.boirie@parrot.com>

 *

 * Note this is still rather experimental and may eat babies.

 *

 * Todo

 * * Protect against connection of devices that 'need' the top half

 *   handler.

 * * Work out how to run top half handlers in this context if it is

 *   safe to do so (timestamp grabbing for example)

 *

 * Tested against a max1363. Used about 33% cpu for the thread and 20%

 * for generic_buffer piping to /dev/null. Watermark set at 64 on a 128

 * element kfifo buffer.

 */

​

#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/platform_device.h>

#include <linux/slab.h>

#include <linux/irq_work.h>

#include <linux/kthread.h>

#include <linux/freezer.h>

​

#include <linux/iio/iio.h>

#include <linux/iio/trigger.h>

#include <linux/iio/sw_trigger.h>

​

struct iio_loop_info {

    struct iio_sw_trigger swt;

    struct task_struct *task;

};

​

static const struct config_item_type iio_loop_type = {

    .ct_owner = THIS_MODULE,

};

​

static int iio_loop_thread(void *data)

{

    struct iio_trigger *trig = data;

​

    set_freezable();

​

    do {

        iio_trigger_poll_chained(trig);

    } while (likely(!kthread_freezable_should_stop(NULL)));

​

    return 0;

}

​

static int iio_loop_trigger_set_state(struct iio_trigger *trig, bool state)

{

    struct iio_loop_info *loop_trig = iio_trigger_get_drvdata(trig);

​

    if (state) {

        loop_trig->task = kthread_run(iio_loop_thread,

                          trig, trig->name);

        if (unlikely(IS_ERR(loop_trig->task))) {