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/*
* 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))) {
dev_err(&trig->dev,
"failed to create trigger loop thread\n");
return PTR_ERR(loop_trig->task);
}
} else {
kthread_stop(loop_trig->task);
}
return 0;
}
static const struct iio_trigger_ops iio_loop_trigger_ops = {
.set_trigger_state = iio_loop_trigger_set_state,
};
static struct iio_sw_trigger *iio_trig_loop_probe(const char *name)
{
struct iio_loop_info *trig_info;
int ret;
trig_info = kzalloc(sizeof(*trig_info), GFP_KERNEL);
if (!trig_info)
return ERR_PTR(-ENOMEM);
trig_info->swt.trigger = iio_trigger_alloc("%s", name);
if (!trig_info->swt.trigger) {
ret = -ENOMEM;
goto err_free_trig_info;
}
iio_trigger_set_drvdata(trig_info->swt.trigger, trig_info);
trig_info->swt.trigger->ops = &iio_loop_trigger_ops;
ret = iio_trigger_register(trig_info->swt.trigger);
if (ret)
goto err_free_trigger;
iio_swt_group_init_type_name(&trig_info->swt, name, &iio_loop_type);
return &trig_info->swt;
err_free_trigger:
iio_trigger_free(trig_info->swt.trigger);
err_free_trig_info:
kfree(trig_info);
return ERR_PTR(ret);
}
static int iio_trig_loop_remove(struct iio_sw_trigger *swt)
{
struct iio_loop_info *trig_info;
trig_info = iio_trigger_get_drvdata(swt->trigger);
iio_trigger_unregister(swt->trigger);
iio_trigger_free(swt->trigger);
kfree(trig_info);
return 0;
}
static const struct iio_sw_trigger_ops iio_trig_loop_ops = {
.probe = iio_trig_loop_probe,
.remove = iio_trig_loop_remove,
};
static struct iio_sw_trigger_type iio_trig_loop = {
.name = "loop",
.owner = THIS_MODULE,
.ops = &iio_trig_loop_ops,
};
module_iio_sw_trigger_driver(iio_trig_loop);
MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>");
MODULE_DESCRIPTION("Loop based trigger for the iio subsystem");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:iio-trig-loop");
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