drivers/staging/iio/trigger/iio-trig-periodic-rtc.c

/* The industrial I/O periodic RTC trigger driver
 *
 * Copyright (c) 2008 Jonathan Cameron
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published by
 * the Free Software Foundation.
 *
 * This is a heavily rewritten version of the periodic timer system in
 * earlier version of industrialio.  It supplies the same functionality
 * but via a trigger rather than a specific periodic timer system.
 */

#include <linux/platform_device.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/rtc.h>
#include <linux/iio/iio.h>
#include <linux/iio/trigger.h>

static LIST_HEAD(iio_prtc_trigger_list);
static DEFINE_MUTEX(iio_prtc_trigger_list_lock);

struct iio_prtc_trigger_info {
	struct rtc_device *rtc;
	unsigned int frequency;
	struct rtc_task task;
	bool state;
};

static int iio_trig_periodic_rtc_set_state(struct iio_trigger *trig, bool state)
{
	struct iio_prtc_trigger_info *trig_info = iio_trigger_get_drvdata(trig);
	int ret;

	if (trig_info->frequency == 0 && state)
		return -EINVAL;
	dev_dbg(&trig_info->rtc->dev, "trigger frequency is %u\n",
		trig_info->frequency);
	ret = rtc_irq_set_state(trig_info->rtc, &trig_info->task, state);
	if (ret == 0)
		trig_info->state = state;

	return ret;
}

static ssize_t iio_trig_periodic_read_freq(struct device *dev,
					   struct device_attribute *attr,
					   char *buf)
{
	struct iio_trigger *trig = to_iio_trigger(dev);
	struct iio_prtc_trigger_info *trig_info = iio_trigger_get_drvdata(trig);

	return sprintf(buf, "%u\n", trig_info->frequency);
}

static ssize_t iio_trig_periodic_write_freq(struct device *dev,
					    struct device_attribute *attr,
					    const char *buf,
					    size_t len)
{
	struct iio_trigger *trig = to_iio_trigger(dev);
	struct iio_prtc_trigger_info *trig_info = iio_trigger_get_drvdata(trig);
	unsigned int val;
	int ret;

	ret = kstrtouint(buf, 10, &val);
	if (ret)
		goto error_ret;

	if (val > 0) {
		ret = rtc_irq_set_freq(trig_info->rtc, &trig_info->task, val);
		if (ret == 0 && trig_info->state && trig_info->frequency == 0)
			ret = rtc_irq_set_state(trig_info->rtc,
						&trig_info->task, 1);
	} else {
		ret = rtc_irq_set_state(trig_info->rtc, &trig_info->task, 0);
	}
	if (ret)
		goto error_ret;

	trig_info->frequency = val;

	return len;

error_ret:
	return ret;
}

static DEVICE_ATTR(frequency, S_IRUGO | S_IWUSR,
	    iio_trig_periodic_read_freq,
	    iio_trig_periodic_write_freq);

static struct attribute *iio_trig_prtc_attrs[] = {
	&dev_attr_frequency.attr,
	NULL,
};

static const struct attribute_group iio_trig_prtc_attr_group = {
	.attrs = iio_trig_prtc_attrs,
};

static const struct attribute_group *iio_trig_prtc_attr_groups[] = {
	&iio_trig_prtc_attr_group,
	NULL
};

static void iio_prtc_trigger_poll(void *private_data)
{
	iio_trigger_poll(private_data);
}

static const struct iio_trigger_ops iio_prtc_trigger_ops = {
	.owner = THIS_MODULE,
	.set_trigger_state = &iio_trig_periodic_rtc_set_state,
};

static int iio_trig_periodic_rtc_probe(struct platform_device *dev)
{
	char **pdata = dev->dev.platform_data;
	struct iio_prtc_trigger_info *trig_info;
	struct iio_trigger *trig, *trig2;

	int i, ret;

	for (i = 0;; i++) {
		if (!pdata[i])
			break;
		trig = iio_trigger_alloc("periodic%s", pdata[i]);
		if (!trig) {
			ret = -ENOMEM;
			goto error_free_completed_registrations;
		}
		list_add(&trig->alloc_list, &iio_prtc_trigger_list);

		trig_info = kzalloc(sizeof(*trig_info), GFP_KERNEL);
		if (!trig_info) {
			ret = -ENOMEM;
			goto error_put_trigger_and_remove_from_list;
		}
		iio_trigger_set_drvdata(trig, trig_info);
		trig->ops = &iio_prtc_trigger_ops;
		/* RTC access */
		trig_info->rtc = rtc_class_open(pdata[i]);
		if (!trig_info->rtc) {
			ret = -EINVAL;
			goto error_free_trig_info;
		}
		trig_info->task.func = iio_prtc_trigger_poll;
		trig_info->task.private_data = trig;
		ret = rtc_irq_register(trig_info->rtc, &trig_info->task);
		if (ret)
			goto error_close_rtc;
		trig->dev.groups = iio_trig_prtc_attr_groups;
		ret = iio_trigger_register(trig);
		if (ret)
			goto error_unregister_rtc_irq;
	}
	return 0;
error_unregister_rtc_irq:
	rtc_irq_unregister(trig_info->rtc, &trig_info->task);
error_close_rtc:
	rtc_class_close(trig_info->rtc);
error_free_trig_info:
	kfree(trig_info);
error_put_trigger_and_remove_from_list:
	list_del(&trig->alloc_list);
	iio_trigger_put(trig);
error_free_completed_registrations:
	list_for_each_entry_safe(trig,
				 trig2,
				 &iio_prtc_trigger_list,
				 alloc_list) {
		trig_info = iio_trigger_get_drvdata(trig);
		rtc_irq_unregister(trig_info->rtc, &trig_info->task);
		rtc_class_close(trig_info->rtc);
		kfree(trig_info);
		iio_trigger_unregister(trig);
	}
	return ret;
}

static int iio_trig_periodic_rtc_remove(struct platform_device *dev)
{
	struct iio_trigger *trig, *trig2;
	struct iio_prtc_trigger_info *trig_info;

	mutex_lock(&iio_prtc_trigger_list_lock);
	list_for_each_entry_safe(trig,
				 trig2,
				 &iio_prtc_trigger_list,
				 alloc_list) {
		trig_info = iio_trigger_get_drvdata(trig);
		rtc_irq_unregister(trig_info->rtc, &trig_info->task);
		rtc_class_close(trig_info->rtc);
		kfree(trig_info);
		iio_trigger_unregister(trig);
	}
	mutex_unlock(&iio_prtc_trigger_list_lock);
	return 0;
}

static struct platform_driver iio_trig_periodic_rtc_driver = {
	.probe = iio_trig_periodic_rtc_probe,
	.remove = iio_trig_periodic_rtc_remove,
	.driver = {
		.name = "iio_prtc_trigger",
	},
};

module_platform_driver(iio_trig_periodic_rtc_driver);

MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>");
MODULE_DESCRIPTION("Periodic realtime clock trigger for the iio subsystem");
MODULE_LICENSE("GPL v2");