[linux-2.6-block.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>

#define DEFAULT_TIMEOUT_MS 3000
/*
 * 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 u32 timeout = DEFAULT_TIMEOUT_MS;
static u32 active_delay = 100;
static u32 inactive_delay = 100;

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(active_delay);

	/* drive inactive, also active->inactive edge */
	gpiod_set_value_cansleep(reset_gpio, 0);
	mdelay(inactive_delay);

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

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

	WARN_ON(1);
}

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

	/* 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;
	}

	input = device_property_read_bool(&pdev->dev, "input");
	if (input)
		flags = GPIOD_IN;
	else
		flags = GPIOD_OUT_LOW;

	device_property_read_u32(&pdev->dev, "active-delay-ms", &active_delay);
	device_property_read_u32(&pdev->dev, "inactive-delay-ms",
				 &inactive_delay);
	device_property_read_u32(&pdev->dev, "timeout-ms", &timeout);

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

	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>
96ff0f5c JL	21
d85b4f7b	22	#define DEFAULT_TIMEOUT_MS 3000
96ff0f5c JL	23	/*
	24	* Hold configuration here, cannot be more than one instance of the driver
	25	* since pm_power_off itself is global.
	26	*/
86336ba4	27	static struct gpio_desc *reset_gpio;
d85b4f7b	28	static u32 timeout = DEFAULT_TIMEOUT_MS;
76ee875c HS	29	static u32 active_delay = 100;
76ee875c HS	30	static u32 inactive_delay = 100;
96ff0f5c JL	31
	32	static void gpio_poweroff_do_poweroff(void)
	33	{
86336ba4	34	BUG_ON(!reset_gpio);
96ff0f5c	35
5343527b	36	/* drive it active, also inactive->active edge */
86336ba4	37	gpiod_direction_output(reset_gpio, 1);
76ee875c HS	38	mdelay(active_delay);
76ee875c HS	39
5343527b	40	/* drive inactive, also active->inactive edge */
77142a61	41	gpiod_set_value_cansleep(reset_gpio, 0);
76ee875c	42	mdelay(inactive_delay);
5343527b AL	43
5343527b AL	44	/* drive it active, also inactive->active edge */
77142a61	45	gpiod_set_value_cansleep(reset_gpio, 1);
96ff0f5c JL	46
96ff0f5c JL	47	/* give it some time */
d85b4f7b	48	mdelay(timeout);
96ff0f5c JL	49
	50	WARN_ON(1);
	51	}
	52
6d2cea4f	53	static int gpio_poweroff_probe(struct platform_device *pdev)
96ff0f5c	54	{
96ff0f5c	55	bool input = false;
a34c0a8b	56	enum gpiod_flags flags;
96ff0f5c JL	57
	58	/* If a pm_power_off function has already been added, leave it alone */
	59	if (pm_power_off != NULL) {
86336ba4 LW	60	dev_err(&pdev->dev,
86336ba4 LW	61	"%s: pm_power_off function already registered",
96ff0f5c JL	62	__func__);
	63	return -EBUSY;
	64	}
	65
d85b4f7b	66	input = device_property_read_bool(&pdev->dev, "input");
a34c0a8b UKK	67	if (input)
	68	flags = GPIOD_IN;
	69	else
	70	flags = GPIOD_OUT_LOW;
96ff0f5c	71
76ee875c HS	72	device_property_read_u32(&pdev->dev, "active-delay-ms", &active_delay);
	73	device_property_read_u32(&pdev->dev, "inactive-delay-ms",
	74	&inactive_delay);
d85b4f7b MF	75	device_property_read_u32(&pdev->dev, "timeout-ms", &timeout);
d85b4f7b MF	76
a34c0a8b UKK	77	reset_gpio = devm_gpiod_get(&pdev->dev, NULL, flags);
	78	if (IS_ERR(reset_gpio))
	79	return PTR_ERR(reset_gpio);
96ff0f5c JL	80
	81	pm_power_off = &gpio_poweroff_do_poweroff;
	82	return 0;
96ff0f5c JL	83	}
96ff0f5c JL	84
6d2cea4f	85	static int gpio_poweroff_remove(struct platform_device *pdev)
96ff0f5c	86	{
96ff0f5c JL	87	if (pm_power_off == &gpio_poweroff_do_poweroff)
	88	pm_power_off = NULL;
	89
	90	return 0;
	91	}
	92
	93	static const struct of_device_id of_gpio_poweroff_match[] = {
	94	{ .compatible = "gpio-poweroff", },
	95	{},
	96	};
	97
	98	static struct platform_driver gpio_poweroff_driver = {
	99	.probe = gpio_poweroff_probe,
6d2cea4f	100	.remove = gpio_poweroff_remove,
96ff0f5c	101	.driver = {
5343527b	102	.name = "poweroff-gpio",
5343527b AL	103	.of_match_table = of_gpio_poweroff_match,
5343527b AL	104	},
96ff0f5c JL	105	};
	106
	107	module_platform_driver(gpio_poweroff_driver);
	108
	109	MODULE_AUTHOR("Jamie Lentin <jm@lentin.co.uk>");
	110	MODULE_DESCRIPTION("GPIO poweroff driver");
5343527b	111	MODULE_LICENSE("GPL v2");
96ff0f5c	112	MODULE_ALIAS("platform:poweroff-gpio");