[deliverable/linux.git] / drivers / power / reset / gpio-poweroff.c

/*
 * Toggles a GPIO pin to power down a device
 *
 * Jamie Lentin <jm@lentin.co.uk>
 * Andrew Lunn <andrew@lunn.ch>
 *
 * Copyright (C) 2012 Jamie Lentin
 *
 * 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.
 *
 */
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/platform_device.h>
#include <linux/gpio/consumer.h>
#include <linux/of_platform.h>
#include <linux/module.h>

/*
 * Hold configuration here, cannot be more than one instance of the driver
 * since pm_power_off itself is global.
 */
static struct gpio_desc *reset_gpio;

static void gpio_poweroff_do_poweroff(void)
{
	BUG_ON(!reset_gpio);

	/* drive it active, also inactive->active edge */
	gpiod_direction_output(reset_gpio, 1);
	mdelay(100);
	/* drive inactive, also active->inactive edge */
	gpiod_set_value(reset_gpio, 0);
	mdelay(100);

	/* drive it active, also inactive->active edge */
	gpiod_set_value(reset_gpio, 1);

	/* give it some time */
	mdelay(3000);

	WARN_ON(1);
}

static int gpio_poweroff_probe(struct platform_device *pdev)
{
	bool input = false;

	/* If a pm_power_off function has already been added, leave it alone */
	if (pm_power_off != NULL) {
		dev_err(&pdev->dev,
			"%s: pm_power_off function already registered",
		       __func__);
		return -EBUSY;
	}

	reset_gpio = devm_gpiod_get(&pdev->dev, NULL);
	if (IS_ERR(reset_gpio))
		return PTR_ERR(reset_gpio);

	input = of_property_read_bool(pdev->dev.of_node, "input");

	if (input) {
		if (gpiod_direction_input(reset_gpio)) {
			dev_err(&pdev->dev,
				"Could not set direction of reset GPIO to input\n");
			return -ENODEV;
		}
	} else {
		if (gpiod_direction_output(reset_gpio, 0)) {
			dev_err(&pdev->dev,
				"Could not set direction of reset GPIO\n");
			return -ENODEV;
		}
	}

	pm_power_off = &gpio_poweroff_do_poweroff;
	return 0;
}

static int gpio_poweroff_remove(struct platform_device *pdev)
{
	if (pm_power_off == &gpio_poweroff_do_poweroff)
		pm_power_off = NULL;

	return 0;
}

static const struct of_device_id of_gpio_poweroff_match[] = {
	{ .compatible = "gpio-poweroff", },
	{},
};

static struct platform_driver gpio_poweroff_driver = {
	.probe = gpio_poweroff_probe,
	.remove = gpio_poweroff_remove,
	.driver = {
		.name = "poweroff-gpio",
		.of_match_table = of_gpio_poweroff_match,
	},
};

module_platform_driver(gpio_poweroff_driver);

MODULE_AUTHOR("Jamie Lentin <jm@lentin.co.uk>");
MODULE_DESCRIPTION("GPIO poweroff driver");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:poweroff-gpio");
Commit	Line	Data
96ff0f5c JL	1	/*
	2	* Toggles a GPIO pin to power down a device
	3	*
	4	* Jamie Lentin <jm@lentin.co.uk>
	5	* Andrew Lunn <andrew@lunn.ch>
	6	*
	7	* Copyright (C) 2012 Jamie Lentin
	8	*
	9	* This program is free software; you can redistribute it and/or modify
	10	* it under the terms of the GNU General Public License version 2 as
	11	* published by the Free Software Foundation.
	12	*
	13	*/
	14	#include <linux/kernel.h>
	15	#include <linux/init.h>
	16	#include <linux/delay.h>
	17	#include <linux/platform_device.h>
86336ba4	18	#include <linux/gpio/consumer.h>
96ff0f5c	19	#include <linux/of_platform.h>
96ff0f5c JL	20	#include <linux/module.h>
	21
	22	/*
	23	* Hold configuration here, cannot be more than one instance of the driver
	24	* since pm_power_off itself is global.
	25	*/
86336ba4	26	static struct gpio_desc *reset_gpio;
96ff0f5c JL	27
	28	static void gpio_poweroff_do_poweroff(void)
	29	{
86336ba4	30	BUG_ON(!reset_gpio);
96ff0f5c	31
5343527b	32	/* drive it active, also inactive->active edge */
86336ba4	33	gpiod_direction_output(reset_gpio, 1);
96ff0f5c	34	mdelay(100);
5343527b	35	/* drive inactive, also active->inactive edge */
86336ba4	36	gpiod_set_value(reset_gpio, 0);
96ff0f5c	37	mdelay(100);
5343527b AL	38
5343527b AL	39	/* drive it active, also inactive->active edge */
86336ba4	40	gpiod_set_value(reset_gpio, 1);
96ff0f5c JL	41
	42	/* give it some time */
	43	mdelay(3000);
	44
	45	WARN_ON(1);
	46	}
	47
6d2cea4f	48	static int gpio_poweroff_probe(struct platform_device *pdev)
96ff0f5c	49	{
96ff0f5c	50	bool input = false;
96ff0f5c JL	51
	52	/* If a pm_power_off function has already been added, leave it alone */
	53	if (pm_power_off != NULL) {
86336ba4 LW	54	dev_err(&pdev->dev,
86336ba4 LW	55	"%s: pm_power_off function already registered",
96ff0f5c JL	56	__func__);
	57	return -EBUSY;
	58	}
	59
86336ba4 LW	60	reset_gpio = devm_gpiod_get(&pdev->dev, NULL);
	61	if (IS_ERR(reset_gpio))
	62	return PTR_ERR(reset_gpio);
96ff0f5c	63
5343527b	64	input = of_property_read_bool(pdev->dev.of_node, "input");
96ff0f5c	65
96ff0f5c	66	if (input) {
86336ba4 LW	67	if (gpiod_direction_input(reset_gpio)) {
	68	dev_err(&pdev->dev,
	69	"Could not set direction of reset GPIO to input\n");
	70	return -ENODEV;
96ff0f5c JL	71	}
96ff0f5c JL	72	} else {
86336ba4 LW	73	if (gpiod_direction_output(reset_gpio, 0)) {
	74	dev_err(&pdev->dev,
	75	"Could not set direction of reset GPIO\n");
	76	return -ENODEV;
96ff0f5c JL	77	}
	78	}
	79
	80	pm_power_off = &gpio_poweroff_do_poweroff;
	81	return 0;
96ff0f5c JL	82	}
96ff0f5c JL	83
6d2cea4f	84	static int gpio_poweroff_remove(struct platform_device *pdev)
96ff0f5c	85	{
96ff0f5c JL	86	if (pm_power_off == &gpio_poweroff_do_poweroff)
	87	pm_power_off = NULL;
	88
	89	return 0;
	90	}
	91
	92	static const struct of_device_id of_gpio_poweroff_match[] = {
	93	{ .compatible = "gpio-poweroff", },
	94	{},
	95	};
	96
	97	static struct platform_driver gpio_poweroff_driver = {
	98	.probe = gpio_poweroff_probe,
6d2cea4f	99	.remove = gpio_poweroff_remove,
96ff0f5c	100	.driver = {
5343527b	101	.name = "poweroff-gpio",
5343527b AL	102	.of_match_table = of_gpio_poweroff_match,
5343527b AL	103	},
96ff0f5c JL	104	};
	105
	106	module_platform_driver(gpio_poweroff_driver);
	107
	108	MODULE_AUTHOR("Jamie Lentin <jm@lentin.co.uk>");
	109	MODULE_DESCRIPTION("GPIO poweroff driver");
5343527b	110	MODULE_LICENSE("GPL v2");
96ff0f5c	111	MODULE_ALIAS("platform:poweroff-gpio");