cregit-Linux how code gets into the kernel

Release 4.8 drivers/iio/trigger/iio-trig-loop.c

/*
 * 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 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; }

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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; }

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static const struct iio_trigger_ops iio_loop_trigger_ops = { .set_trigger_state = iio_loop_trigger_set_state, .owner = THIS_MODULE, };
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); }

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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; }

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jonathan cameronjonathan cameron47100.00%1100.00%
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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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jonathan cameronjonathan cameron482100.00%1100.00%
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