linux_kernel/drivers/iio/trigger/stm32-lptimer-trigger.c

/*
 * STM32 Low-Power Timer Trigger driver
 *
 * Copyright (C) STMicroelectronics 2017
 *
 * Author: Fabrice Gasnier <fabrice.gasnier@st.com>.
 *
 * License terms:  GNU General Public License (GPL), version 2
 *
 * Inspired by Benjamin Gaignard's stm32-timer-trigger driver
 */

#include <linux/iio/timer/stm32-lptim-trigger.h>
#include <linux/mfd/stm32-lptimer.h>
#include <linux/module.h>
#include <linux/platform_device.h>

/* List Low-Power Timer triggers */
static const char * const stm32_lptim_triggers[] = {
	LPTIM1_OUT,
	LPTIM2_OUT,
	LPTIM3_OUT,
};

struct stm32_lptim_trigger {
	struct device *dev;
	const char *trg;
};

static int stm32_lptim_validate_device(struct iio_trigger *trig,
				       struct iio_dev *indio_dev)
{
	if (indio_dev->modes & INDIO_HARDWARE_TRIGGERED)
		return 0;

	return -EINVAL;
}

static const struct iio_trigger_ops stm32_lptim_trigger_ops = {
	.owner = THIS_MODULE,
	.validate_device = stm32_lptim_validate_device,
};

/**
 * is_stm32_lptim_trigger
 * @trig: trigger to be checked
 *
 * return true if the trigger is a valid STM32 IIO Low-Power Timer Trigger
 * either return false
 */
bool is_stm32_lptim_trigger(struct iio_trigger *trig)
{
	return (trig->ops == &stm32_lptim_trigger_ops);
}
EXPORT_SYMBOL(is_stm32_lptim_trigger);

static int stm32_lptim_setup_trig(struct stm32_lptim_trigger *priv)
{
	struct iio_trigger *trig;

	trig = devm_iio_trigger_alloc(priv->dev, "%s", priv->trg);
	if  (!trig)
		return -ENOMEM;

	trig->dev.parent = priv->dev->parent;
	trig->ops = &stm32_lptim_trigger_ops;
	iio_trigger_set_drvdata(trig, priv);

	return devm_iio_trigger_register(priv->dev, trig);
}

static int stm32_lptim_trigger_probe(struct platform_device *pdev)
{
	struct stm32_lptim_trigger *priv;
	u32 index;
	int ret;

	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
	if (!priv)
		return -ENOMEM;

	if (of_property_read_u32(pdev->dev.of_node, "reg", &index))
		return -EINVAL;

	if (index >= ARRAY_SIZE(stm32_lptim_triggers))
		return -EINVAL;

	priv->dev = &pdev->dev;
	priv->trg = stm32_lptim_triggers[index];

	ret = stm32_lptim_setup_trig(priv);
	if (ret)
		return ret;

	platform_set_drvdata(pdev, priv);

	return 0;
}

static const struct of_device_id stm32_lptim_trig_of_match[] = {
	{ .compatible = "st,stm32-lptimer-trigger", },
	{},
};
MODULE_DEVICE_TABLE(of, stm32_lptim_trig_of_match);

static struct platform_driver stm32_lptim_trigger_driver = {
	.probe = stm32_lptim_trigger_probe,
	.driver = {
		.name = "stm32-lptimer-trigger",
		.of_match_table = stm32_lptim_trig_of_match,
	},
};
module_platform_driver(stm32_lptim_trigger_driver);

MODULE_AUTHOR("Fabrice Gasnier <fabrice.gasnier@st.com>");
MODULE_ALIAS("platform:stm32-lptimer-trigger");
MODULE_DESCRIPTION("STMicroelectronics STM32 LPTIM trigger driver");
MODULE_LICENSE("GPL v2");