drivers/power/reset/ltc2952-poweroff.c - arm/linux - Git at Google

 /*
  * LTC2952 (PowerPath) driver
  *
  * Copyright (C) 2014, Xsens Technologies BV <info@xsens.com>
  * Maintainer: René Moll <linux@r-moll.nl>
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
  * as published by the Free Software Foundation; either version 2
  * of the License, or (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * ----------------------------------------
  * - Description
  * ----------------------------------------
  *
  * This driver is to be used with an external PowerPath Controller (LTC2952).
  * Its function is to determine when a external shut down is triggered
  * and react by properly shutting down the system.
  *
  * This driver expects a device tree with a ltc2952 entry for pin mapping.
  *
  * ----------------------------------------
  * - GPIO
  * ----------------------------------------
  *
  * The following GPIOs are used:
  * - trigger (input)
  *     A level change indicates the shut-down trigger. If it's state reverts
  *     within the time-out defined by trigger_delay, the shut down is not
  *     executed. If no pin is assigned to this input, the driver will start the
  *     watchdog toggle immediately. The chip will only power off the system if
  *     it is requested to do so through the kill line.
  *
  * - watchdog (output)
  *     Once a shut down is triggered, the driver will toggle this signal,
  *     with an internal (wde_interval) to stall the hardware shut down.
  *
  * - kill (output)
  *     The last action during shut down is triggering this signalling, such
  *     that the PowerPath Control will power down the hardware.
  *
  * ----------------------------------------
  * - Interrupts
  * ----------------------------------------
  *
  * The driver requires a non-shared, edge-triggered interrupt on the trigger
  * GPIO.
  *
  */

 #include <linux/kernel.h>
 #include <linux/init.h>
 #include <linux/interrupt.h>
 #include <linux/device.h>
 #include <linux/platform_device.h>
 #include <linux/ktime.h>
 #include <linux/slab.h>
 #include <linux/kmod.h>
 #include <linux/module.h>
 #include <linux/gpio/consumer.h>
 #include <linux/reboot.h>

 struct ltc2952_poweroff {
 	struct hrtimer timer_trigger;
 	struct hrtimer timer_wde;

 	ktime_t trigger_delay;
 	ktime_t wde_interval;

 	struct device *dev;

 	struct gpio_desc *gpio_trigger;
 	struct gpio_desc *gpio_watchdog;
 	struct gpio_desc *gpio_kill;

 	bool kernel_panic;
 	struct notifier_block panic_notifier;
 };

 #define to_ltc2952(p, m) container_of(p, struct ltc2952_poweroff, m)

 /*
  * This global variable is only needed for pm_power_off. We should
  * remove it entirely once we don't need the global state anymore.
  */
 static struct ltc2952_poweroff *ltc2952_data;

 /**
  * ltc2952_poweroff_timer_wde - Timer callback
  * Toggles the watchdog reset signal each wde_interval
  *
  * @timer: corresponding timer
  *
  * Returns HRTIMER_RESTART for an infinite loop which will only stop when the
  * machine actually shuts down
  */
 static enum hrtimer_restart ltc2952_poweroff_timer_wde(struct hrtimer *timer)
 {
 	ktime_t now;
 	int state;
 	unsigned long overruns;
 	struct ltc2952_poweroff *data = to_ltc2952(timer, timer_wde);

 	if (data->kernel_panic)
 		return HRTIMER_NORESTART;

 	state = gpiod_get_value(data->gpio_watchdog);
 	gpiod_set_value(data->gpio_watchdog, !state);

 	now = hrtimer_cb_get_time(timer);
 	overruns = hrtimer_forward(timer, now, data->wde_interval);

 	return HRTIMER_RESTART;
 }

 static void ltc2952_poweroff_start_wde(struct ltc2952_poweroff *data)
 {
 	hrtimer_start(&data->timer_wde, data->wde_interval, HRTIMER_MODE_REL);
 }

 static enum hrtimer_restart
 ltc2952_poweroff_timer_trigger(struct hrtimer *timer)
 {
 	struct ltc2952_poweroff *data = to_ltc2952(timer, timer_trigger);

 	ltc2952_poweroff_start_wde(data);
 	dev_info(data->dev, "executing shutdown\n");
 	orderly_poweroff(true);

 	return HRTIMER_NORESTART;
 }

 /**
  * ltc2952_poweroff_handler - Interrupt handler
  * Triggered each time the trigger signal changes state and (de)activates a
  * time-out (timer_trigger). Once the time-out is actually reached the shut
  * down is executed.
  *
  * @irq: IRQ number
  * @dev_id: pointer to the main data structure
  */
 static irqreturn_t ltc2952_poweroff_handler(int irq, void *dev_id)
 {
 	struct ltc2952_poweroff *data = dev_id;

 	if (data->kernel_panic || hrtimer_active(&data->timer_wde)) {
 		/* shutdown is already triggered, nothing to do any more */
 		return IRQ_HANDLED;
 	}

 	if (gpiod_get_value(data->gpio_trigger)) {
 		hrtimer_start(&data->timer_trigger, data->trigger_delay,
 			      HRTIMER_MODE_REL);
 	} else {
 		hrtimer_cancel(&data->timer_trigger);
 	}
 	return IRQ_HANDLED;
 }

 static void ltc2952_poweroff_kill(void)
 {
 	gpiod_set_value(ltc2952_data->gpio_kill, 1);
 }

 static void ltc2952_poweroff_default(struct ltc2952_poweroff *data)
 {
 	data->wde_interval = 300L * 1E6L;
 	data->trigger_delay = ktime_set(2, 500L*1E6L);

 	hrtimer_init(&data->timer_trigger, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 	data->timer_trigger.function = ltc2952_poweroff_timer_trigger;

 	hrtimer_init(&data->timer_wde, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 	data->timer_wde.function = ltc2952_poweroff_timer_wde;
 }

 static int ltc2952_poweroff_init(struct platform_device *pdev)
 {
 	int ret;
 	struct ltc2952_poweroff *data = platform_get_drvdata(pdev);

 	ltc2952_poweroff_default(data);

 	data->gpio_watchdog = devm_gpiod_get(&pdev->dev, "watchdog",
 					     GPIOD_OUT_LOW);
 	if (IS_ERR(data->gpio_watchdog)) {
 		ret = PTR_ERR(data->gpio_watchdog);
 		dev_err(&pdev->dev, "unable to claim gpio \"watchdog\"\n");
 		return ret;
 	}

 	data->gpio_kill = devm_gpiod_get(&pdev->dev, "kill", GPIOD_OUT_LOW);
 	if (IS_ERR(data->gpio_kill)) {
 		ret = PTR_ERR(data->gpio_kill);
 		dev_err(&pdev->dev, "unable to claim gpio \"kill\"\n");
 		return ret;
 	}

 	data->gpio_trigger = devm_gpiod_get_optional(&pdev->dev, "trigger",
 						     GPIOD_IN);
 	if (IS_ERR(data->gpio_trigger)) {
 		/*
 		 * It's not a problem if the trigger gpio isn't available, but
 		 * it is worth a warning if its use was defined in the device
 		 * tree.
 		 */
 		dev_err(&pdev->dev, "unable to claim gpio \"trigger\"\n");
 		data->gpio_trigger = NULL;
 	}

 	if (devm_request_irq(&pdev->dev, gpiod_to_irq(data->gpio_trigger),
 			     ltc2952_poweroff_handler,
 			     (IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING),
 			     "ltc2952-poweroff",
 			     data)) {
 		/*
 		 * Some things may have happened:
 		 * - No trigger input was defined
 		 * - Claiming the GPIO failed
 		 * - We could not map to an IRQ
 		 * - We couldn't register an interrupt handler
 		 *
 		 * None of these really are problems, but all of them
 		 * disqualify the push button from controlling the power.
 		 *
 		 * It is therefore important to note that if the ltc2952
 		 * detects a button press for long enough, it will still start
 		 * its own powerdown window and cut the power on us if we don't
 		 * start the watchdog trigger.
 		 */
 		if (data->gpio_trigger) {
 			dev_warn(&pdev->dev,
 				 "unable to configure the trigger interrupt\n");
 			devm_gpiod_put(&pdev->dev, data->gpio_trigger);
 			data->gpio_trigger = NULL;
 		}
 		dev_info(&pdev->dev,
 			 "power down trigger input will not be used\n");
 		ltc2952_poweroff_start_wde(data);
 	}

 	return 0;
 }

 static int ltc2952_poweroff_notify_panic(struct notifier_block *nb,
 					 unsigned long code, void *unused)
 {
 	struct ltc2952_poweroff *data = to_ltc2952(nb, panic_notifier);

 	data->kernel_panic = true;
 	return NOTIFY_DONE;
 }

 static int ltc2952_poweroff_probe(struct platform_device *pdev)
 {
 	int ret;
 	struct ltc2952_poweroff *data;

 	if (pm_power_off) {
 		dev_err(&pdev->dev, "pm_power_off already registered");
 		return -EBUSY;
 	}

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

 	data->dev = &pdev->dev;
 	platform_set_drvdata(pdev, data);

 	ret = ltc2952_poweroff_init(pdev);
 	if (ret)
 		return ret;

 	/* TODO: remove ltc2952_data */
 	ltc2952_data = data;
 	pm_power_off = ltc2952_poweroff_kill;

 	data->panic_notifier.notifier_call = ltc2952_poweroff_notify_panic;
 	atomic_notifier_chain_register(&panic_notifier_list,
 				       &data->panic_notifier);
 	dev_info(&pdev->dev, "probe successful\n");

 	return 0;
 }

 static int ltc2952_poweroff_remove(struct platform_device *pdev)
 {
 	struct ltc2952_poweroff *data = platform_get_drvdata(pdev);

 	pm_power_off = NULL;
 	hrtimer_cancel(&data->timer_trigger);
 	hrtimer_cancel(&data->timer_wde);
 	atomic_notifier_chain_unregister(&panic_notifier_list,
 					 &data->panic_notifier);
 	return 0;
 }

 static const struct of_device_id of_ltc2952_poweroff_match[] = {
 	{ .compatible = "lltc,ltc2952"},
 	{},
 };
 MODULE_DEVICE_TABLE(of, of_ltc2952_poweroff_match);

 static struct platform_driver ltc2952_poweroff_driver = {
 	.probe = ltc2952_poweroff_probe,
 	.remove = ltc2952_poweroff_remove,
 	.driver = {
 		.name = "ltc2952-poweroff",
 		.of_match_table = of_ltc2952_poweroff_match,
 	},
 };

 module_platform_driver(ltc2952_poweroff_driver);

 MODULE_AUTHOR("René Moll <rene.moll@xsens.com>");
 MODULE_DESCRIPTION("LTC PowerPath power-off driver");
 MODULE_LICENSE("GPL v2");
	/*
	* LTC2952 (PowerPath) driver
	*
	* Copyright (C) 2014, Xsens Technologies BV <info@xsens.com>
	* Maintainer: René Moll <linux@r-moll.nl>
	*
	* This program is free software; you can redistribute it and/or
	* modify it under the terms of the GNU General Public License
	* as published by the Free Software Foundation; either version 2
	* of the License, or (at your option) any later version.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	* ----------------------------------------
	* - Description
	* ----------------------------------------
	*
	* This driver is to be used with an external PowerPath Controller (LTC2952).
	* Its function is to determine when a external shut down is triggered
	* and react by properly shutting down the system.
	*
	* This driver expects a device tree with a ltc2952 entry for pin mapping.
	*
	* ----------------------------------------
	* - GPIO
	* ----------------------------------------
	*
	* The following GPIOs are used:
	* - trigger (input)
	* A level change indicates the shut-down trigger. If it's state reverts
	* within the time-out defined by trigger_delay, the shut down is not
	* executed. If no pin is assigned to this input, the driver will start the
	* watchdog toggle immediately. The chip will only power off the system if
	* it is requested to do so through the kill line.
	*
	* - watchdog (output)
	* Once a shut down is triggered, the driver will toggle this signal,
	* with an internal (wde_interval) to stall the hardware shut down.
	*
	* - kill (output)
	* The last action during shut down is triggering this signalling, such
	* that the PowerPath Control will power down the hardware.
	*
	* ----------------------------------------
	* - Interrupts
	* ----------------------------------------
	*
	* The driver requires a non-shared, edge-triggered interrupt on the trigger
	* GPIO.
	*
	*/

	#include <linux/kernel.h>
	#include <linux/init.h>
	#include <linux/interrupt.h>
	#include <linux/device.h>
	#include <linux/platform_device.h>
	#include <linux/ktime.h>
	#include <linux/slab.h>
	#include <linux/kmod.h>
	#include <linux/module.h>
	#include <linux/gpio/consumer.h>
	#include <linux/reboot.h>

	struct ltc2952_poweroff {
	struct hrtimer timer_trigger;
	struct hrtimer timer_wde;

	ktime_t trigger_delay;
	ktime_t wde_interval;

	struct device *dev;

	struct gpio_desc *gpio_trigger;
	struct gpio_desc *gpio_watchdog;
	struct gpio_desc *gpio_kill;

	bool kernel_panic;
	struct notifier_block panic_notifier;
	};

	#define to_ltc2952(p, m) container_of(p, struct ltc2952_poweroff, m)

	/*
	* This global variable is only needed for pm_power_off. We should
	* remove it entirely once we don't need the global state anymore.
	*/
	static struct ltc2952_poweroff *ltc2952_data;

	/**
	* ltc2952_poweroff_timer_wde - Timer callback
	* Toggles the watchdog reset signal each wde_interval
	*
	* @timer: corresponding timer
	*
	* Returns HRTIMER_RESTART for an infinite loop which will only stop when the
	* machine actually shuts down
	*/
	static enum hrtimer_restart ltc2952_poweroff_timer_wde(struct hrtimer *timer)
	{
	ktime_t now;
	int state;
	unsigned long overruns;
	struct ltc2952_poweroff *data = to_ltc2952(timer, timer_wde);

	if (data->kernel_panic)
	return HRTIMER_NORESTART;

	state = gpiod_get_value(data->gpio_watchdog);
	gpiod_set_value(data->gpio_watchdog, !state);

	now = hrtimer_cb_get_time(timer);
	overruns = hrtimer_forward(timer, now, data->wde_interval);

	return HRTIMER_RESTART;
	}

	static void ltc2952_poweroff_start_wde(struct ltc2952_poweroff *data)
	{
	hrtimer_start(&data->timer_wde, data->wde_interval, HRTIMER_MODE_REL);
	}

	static enum hrtimer_restart
	ltc2952_poweroff_timer_trigger(struct hrtimer *timer)
	{
	struct ltc2952_poweroff *data = to_ltc2952(timer, timer_trigger);

	ltc2952_poweroff_start_wde(data);
	dev_info(data->dev, "executing shutdown\n");
	orderly_poweroff(true);

	return HRTIMER_NORESTART;
	}

	/**
	* ltc2952_poweroff_handler - Interrupt handler
	* Triggered each time the trigger signal changes state and (de)activates a
	* time-out (timer_trigger). Once the time-out is actually reached the shut
	* down is executed.
	*
	* @irq: IRQ number
	* @dev_id: pointer to the main data structure
	*/
	static irqreturn_t ltc2952_poweroff_handler(int irq, void *dev_id)
	{
	struct ltc2952_poweroff *data = dev_id;

	if (data->kernel_panic \|\| hrtimer_active(&data->timer_wde)) {
	/* shutdown is already triggered, nothing to do any more */
	return IRQ_HANDLED;
	}

	if (gpiod_get_value(data->gpio_trigger)) {
	hrtimer_start(&data->timer_trigger, data->trigger_delay,
	HRTIMER_MODE_REL);
	} else {
	hrtimer_cancel(&data->timer_trigger);
	}
	return IRQ_HANDLED;
	}

	static void ltc2952_poweroff_kill(void)
	{
	gpiod_set_value(ltc2952_data->gpio_kill, 1);
	}

	static void ltc2952_poweroff_default(struct ltc2952_poweroff *data)
	{
	data->wde_interval = 300L * 1E6L;
	data->trigger_delay = ktime_set(2, 500L*1E6L);

	hrtimer_init(&data->timer_trigger, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
	data->timer_trigger.function = ltc2952_poweroff_timer_trigger;

	hrtimer_init(&data->timer_wde, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
	data->timer_wde.function = ltc2952_poweroff_timer_wde;
	}

	static int ltc2952_poweroff_init(struct platform_device *pdev)
	{
	int ret;
	struct ltc2952_poweroff *data = platform_get_drvdata(pdev);

	ltc2952_poweroff_default(data);

	data->gpio_watchdog = devm_gpiod_get(&pdev->dev, "watchdog",
	GPIOD_OUT_LOW);
	if (IS_ERR(data->gpio_watchdog)) {
	ret = PTR_ERR(data->gpio_watchdog);
	dev_err(&pdev->dev, "unable to claim gpio \"watchdog\"\n");
	return ret;
	}

	data->gpio_kill = devm_gpiod_get(&pdev->dev, "kill", GPIOD_OUT_LOW);
	if (IS_ERR(data->gpio_kill)) {
	ret = PTR_ERR(data->gpio_kill);
	dev_err(&pdev->dev, "unable to claim gpio \"kill\"\n");
	return ret;
	}

	data->gpio_trigger = devm_gpiod_get_optional(&pdev->dev, "trigger",
	GPIOD_IN);
	if (IS_ERR(data->gpio_trigger)) {
	/*
	* It's not a problem if the trigger gpio isn't available, but
	* it is worth a warning if its use was defined in the device
	* tree.
	*/
	dev_err(&pdev->dev, "unable to claim gpio \"trigger\"\n");
	data->gpio_trigger = NULL;
	}

	if (devm_request_irq(&pdev->dev, gpiod_to_irq(data->gpio_trigger),
	ltc2952_poweroff_handler,
	(IRQF_TRIGGER_FALLING \| IRQF_TRIGGER_RISING),
	"ltc2952-poweroff",
	data)) {
	/*
	* Some things may have happened:
	* - No trigger input was defined
	* - Claiming the GPIO failed
	* - We could not map to an IRQ
	* - We couldn't register an interrupt handler
	*
	* None of these really are problems, but all of them
	* disqualify the push button from controlling the power.
	*
	* It is therefore important to note that if the ltc2952
	* detects a button press for long enough, it will still start
	* its own powerdown window and cut the power on us if we don't
	* start the watchdog trigger.
	*/
	if (data->gpio_trigger) {
	dev_warn(&pdev->dev,
	"unable to configure the trigger interrupt\n");
	devm_gpiod_put(&pdev->dev, data->gpio_trigger);
	data->gpio_trigger = NULL;
	}
	dev_info(&pdev->dev,
	"power down trigger input will not be used\n");
	ltc2952_poweroff_start_wde(data);
	}

	return 0;
	}

	static int ltc2952_poweroff_notify_panic(struct notifier_block *nb,
	unsigned long code, void *unused)
	{
	struct ltc2952_poweroff *data = to_ltc2952(nb, panic_notifier);

	data->kernel_panic = true;
	return NOTIFY_DONE;
	}

	static int ltc2952_poweroff_probe(struct platform_device *pdev)
	{
	int ret;
	struct ltc2952_poweroff *data;

	if (pm_power_off) {
	dev_err(&pdev->dev, "pm_power_off already registered");
	return -EBUSY;
	}

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

	data->dev = &pdev->dev;
	platform_set_drvdata(pdev, data);

	ret = ltc2952_poweroff_init(pdev);
	if (ret)
	return ret;

	/* TODO: remove ltc2952_data */
	ltc2952_data = data;
	pm_power_off = ltc2952_poweroff_kill;

	data->panic_notifier.notifier_call = ltc2952_poweroff_notify_panic;
	atomic_notifier_chain_register(&panic_notifier_list,
	&data->panic_notifier);
	dev_info(&pdev->dev, "probe successful\n");

	return 0;
	}

	static int ltc2952_poweroff_remove(struct platform_device *pdev)
	{
	struct ltc2952_poweroff *data = platform_get_drvdata(pdev);

	pm_power_off = NULL;
	hrtimer_cancel(&data->timer_trigger);
	hrtimer_cancel(&data->timer_wde);
	atomic_notifier_chain_unregister(&panic_notifier_list,
	&data->panic_notifier);
	return 0;
	}

	static const struct of_device_id of_ltc2952_poweroff_match[] = {
	{ .compatible = "lltc,ltc2952"},
	{},
	};
	MODULE_DEVICE_TABLE(of, of_ltc2952_poweroff_match);

	static struct platform_driver ltc2952_poweroff_driver = {
	.probe = ltc2952_poweroff_probe,
	.remove = ltc2952_poweroff_remove,
	.driver = {
	.name = "ltc2952-poweroff",
	.of_match_table = of_ltc2952_poweroff_match,
	},
	};

	module_platform_driver(ltc2952_poweroff_driver);

	MODULE_AUTHOR("René Moll <rene.moll@xsens.com>");
	MODULE_DESCRIPTION("LTC PowerPath power-off driver");
	MODULE_LICENSE("GPL v2");