drivers/hwmon/gpio-fan.c - third_party/linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * gpio-fan.c - Hwmon driver for fans connected to GPIO lines.
  *
  * Copyright (C) 2010 LaCie
  *
  * Author: Simon Guinot <sguinot@lacie.com>
  */

 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/slab.h>
 #include <linux/interrupt.h>
 #include <linux/irq.h>
 #include <linux/platform_device.h>
 #include <linux/err.h>
 #include <linux/mutex.h>
 #include <linux/hwmon.h>
 #include <linux/gpio/consumer.h>
 #include <linux/of.h>
 #include <linux/of_platform.h>
 #include <linux/thermal.h>

 struct gpio_fan_speed {
 	int rpm;
 	int ctrl_val;
 };

 struct gpio_fan_data {
 	struct device		*dev;
 	struct device		*hwmon_dev;
 	/* Cooling device if any */
 	struct thermal_cooling_device *cdev;
 	struct mutex		lock; /* lock GPIOs operations. */
 	int			num_gpios;
 	struct gpio_desc	**gpios;
 	int			num_speed;
 	struct gpio_fan_speed	*speed;
 	int			speed_index;
 #ifdef CONFIG_PM_SLEEP
 	int			resume_speed;
 #endif
 	bool			pwm_enable;
 	struct gpio_desc	*alarm_gpio;
 	struct work_struct	alarm_work;
 };

 /*
  * Alarm GPIO.
  */

 static void fan_alarm_notify(struct work_struct *ws)
 {
 	struct gpio_fan_data *fan_data =
 		container_of(ws, struct gpio_fan_data, alarm_work);

 	sysfs_notify(&fan_data->hwmon_dev->kobj, NULL, "fan1_alarm");
 	kobject_uevent(&fan_data->hwmon_dev->kobj, KOBJ_CHANGE);
 }

 static irqreturn_t fan_alarm_irq_handler(int irq, void *dev_id)
 {
 	struct gpio_fan_data *fan_data = dev_id;

 	schedule_work(&fan_data->alarm_work);

 	return IRQ_NONE;
 }

 static ssize_t fan1_alarm_show(struct device *dev,
 			       struct device_attribute *attr, char *buf)
 {
 	struct gpio_fan_data *fan_data = dev_get_drvdata(dev);

 	return sprintf(buf, "%d\n",
 		       gpiod_get_value_cansleep(fan_data->alarm_gpio));
 }

 static DEVICE_ATTR_RO(fan1_alarm);

 static int fan_alarm_init(struct gpio_fan_data *fan_data)
 {
 	int alarm_irq;
 	struct device *dev = fan_data->dev;

 	/*
 	 * If the alarm GPIO don't support interrupts, just leave
 	 * without initializing the fail notification support.
 	 */
 	alarm_irq = gpiod_to_irq(fan_data->alarm_gpio);
 	if (alarm_irq <= 0)
 		return 0;

 	INIT_WORK(&fan_data->alarm_work, fan_alarm_notify);
 	irq_set_irq_type(alarm_irq, IRQ_TYPE_EDGE_BOTH);
 	return devm_request_irq(dev, alarm_irq, fan_alarm_irq_handler,
 				IRQF_SHARED, "GPIO fan alarm", fan_data);
 }

 /*
  * Control GPIOs.
  */

 /* Must be called with fan_data->lock held, except during initialization. */
 static void __set_fan_ctrl(struct gpio_fan_data *fan_data, int ctrl_val)
 {
 	int i;

 	for (i = 0; i < fan_data->num_gpios; i++)
 		gpiod_set_value_cansleep(fan_data->gpios[i],
 					 (ctrl_val >> i) & 1);
 }

 static int __get_fan_ctrl(struct gpio_fan_data *fan_data)
 {
 	int i;
 	int ctrl_val = 0;

 	for (i = 0; i < fan_data->num_gpios; i++) {
 		int value;

 		value = gpiod_get_value_cansleep(fan_data->gpios[i]);
 		ctrl_val |= (value << i);
 	}
 	return ctrl_val;
 }

 /* Must be called with fan_data->lock held, except during initialization. */
 static void set_fan_speed(struct gpio_fan_data *fan_data, int speed_index)
 {
 	if (fan_data->speed_index == speed_index)
 		return;

 	__set_fan_ctrl(fan_data, fan_data->speed[speed_index].ctrl_val);
 	fan_data->speed_index = speed_index;
 }

 static int get_fan_speed_index(struct gpio_fan_data *fan_data)
 {
 	int ctrl_val = __get_fan_ctrl(fan_data);
 	int i;

 	for (i = 0; i < fan_data->num_speed; i++)
 		if (fan_data->speed[i].ctrl_val == ctrl_val)
 			return i;

 	dev_warn(fan_data->dev,
 		 "missing speed array entry for GPIO value 0x%x\n", ctrl_val);

 	return -ENODEV;
 }

 static int rpm_to_speed_index(struct gpio_fan_data *fan_data, unsigned long rpm)
 {
 	struct gpio_fan_speed *speed = fan_data->speed;
 	int i;

 	for (i = 0; i < fan_data->num_speed; i++)
 		if (speed[i].rpm >= rpm)
 			return i;

 	return fan_data->num_speed - 1;
 }

 static ssize_t pwm1_show(struct device *dev, struct device_attribute *attr,
 			 char *buf)
 {
 	struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
 	u8 pwm = fan_data->speed_index * 255 / (fan_data->num_speed - 1);

 	return sprintf(buf, "%d\n", pwm);
 }

 static ssize_t pwm1_store(struct device *dev, struct device_attribute *attr,
 			  const char *buf, size_t count)
 {
 	struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
 	unsigned long pwm;
 	int speed_index;
 	int ret = count;

 	if (kstrtoul(buf, 10, &pwm) || pwm > 255)
 		return -EINVAL;

 	mutex_lock(&fan_data->lock);

 	if (!fan_data->pwm_enable) {
 		ret = -EPERM;
 		goto exit_unlock;
 	}

 	speed_index = DIV_ROUND_UP(pwm * (fan_data->num_speed - 1), 255);
 	set_fan_speed(fan_data, speed_index);

 exit_unlock:
 	mutex_unlock(&fan_data->lock);

 	return ret;
 }

 static ssize_t pwm1_enable_show(struct device *dev,
 				struct device_attribute *attr, char *buf)
 {
 	struct gpio_fan_data *fan_data = dev_get_drvdata(dev);

 	return sprintf(buf, "%d\n", fan_data->pwm_enable);
 }

 static ssize_t pwm1_enable_store(struct device *dev,
 				 struct device_attribute *attr,
 				 const char *buf, size_t count)
 {
 	struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
 	unsigned long val;

 	if (kstrtoul(buf, 10, &val) || val > 1)
 		return -EINVAL;

 	if (fan_data->pwm_enable == val)
 		return count;

 	mutex_lock(&fan_data->lock);

 	fan_data->pwm_enable = val;

 	/* Disable manual control mode: set fan at full speed. */
 	if (val == 0)
 		set_fan_speed(fan_data, fan_data->num_speed - 1);

 	mutex_unlock(&fan_data->lock);

 	return count;
 }

 static ssize_t pwm1_mode_show(struct device *dev,
 			      struct device_attribute *attr, char *buf)
 {
 	return sprintf(buf, "0\n");
 }

 static ssize_t fan1_min_show(struct device *dev,
 			     struct device_attribute *attr, char *buf)
 {
 	struct gpio_fan_data *fan_data = dev_get_drvdata(dev);

 	return sprintf(buf, "%d\n", fan_data->speed[0].rpm);
 }

 static ssize_t fan1_max_show(struct device *dev,
 			     struct device_attribute *attr, char *buf)
 {
 	struct gpio_fan_data *fan_data = dev_get_drvdata(dev);

 	return sprintf(buf, "%d\n",
 		       fan_data->speed[fan_data->num_speed - 1].rpm);
 }

 static ssize_t fan1_input_show(struct device *dev,
 			       struct device_attribute *attr, char *buf)
 {
 	struct gpio_fan_data *fan_data = dev_get_drvdata(dev);

 	return sprintf(buf, "%d\n", fan_data->speed[fan_data->speed_index].rpm);
 }

 static ssize_t set_rpm(struct device *dev, struct device_attribute *attr,
 		       const char *buf, size_t count)
 {
 	struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
 	unsigned long rpm;
 	int ret = count;

 	if (kstrtoul(buf, 10, &rpm))
 		return -EINVAL;

 	mutex_lock(&fan_data->lock);

 	if (!fan_data->pwm_enable) {
 		ret = -EPERM;
 		goto exit_unlock;
 	}

 	set_fan_speed(fan_data, rpm_to_speed_index(fan_data, rpm));

 exit_unlock:
 	mutex_unlock(&fan_data->lock);

 	return ret;
 }

 static DEVICE_ATTR_RW(pwm1);
 static DEVICE_ATTR_RW(pwm1_enable);
 static DEVICE_ATTR_RO(pwm1_mode);
 static DEVICE_ATTR_RO(fan1_min);
 static DEVICE_ATTR_RO(fan1_max);
 static DEVICE_ATTR_RO(fan1_input);
 static DEVICE_ATTR(fan1_target, 0644, fan1_input_show, set_rpm);

 static umode_t gpio_fan_is_visible(struct kobject *kobj,
 				   struct attribute *attr, int index)
 {
 	struct device *dev = container_of(kobj, struct device, kobj);
 	struct gpio_fan_data *data = dev_get_drvdata(dev);

 	if (index == 0 && !data->alarm_gpio)
 		return 0;
 	if (index > 0 && !data->gpios)
 		return 0;

 	return attr->mode;
 }

 static struct attribute *gpio_fan_attributes[] = {
 	&dev_attr_fan1_alarm.attr,		/* 0 */
 	&dev_attr_pwm1.attr,			/* 1 */
 	&dev_attr_pwm1_enable.attr,
 	&dev_attr_pwm1_mode.attr,
 	&dev_attr_fan1_input.attr,
 	&dev_attr_fan1_target.attr,
 	&dev_attr_fan1_min.attr,
 	&dev_attr_fan1_max.attr,
 	NULL
 };

 static const struct attribute_group gpio_fan_group = {
 	.attrs = gpio_fan_attributes,
 	.is_visible = gpio_fan_is_visible,
 };

 static const struct attribute_group *gpio_fan_groups[] = {
 	&gpio_fan_group,
 	NULL
 };

 static int fan_ctrl_init(struct gpio_fan_data *fan_data)
 {
 	int num_gpios = fan_data->num_gpios;
 	struct gpio_desc **gpios = fan_data->gpios;
 	int i, err;

 	for (i = 0; i < num_gpios; i++) {
 		/*
 		 * The GPIO descriptors were retrieved with GPIOD_ASIS so here
 		 * we set the GPIO into output mode, carefully preserving the
 		 * current value by setting it to whatever it is already set
 		 * (no surprise changes in default fan speed).
 		 */
 		err = gpiod_direction_output(gpios[i],
 					gpiod_get_value_cansleep(gpios[i]));
 		if (err)
 			return err;
 	}

 	fan_data->pwm_enable = true; /* Enable manual fan speed control. */
 	fan_data->speed_index = get_fan_speed_index(fan_data);
 	if (fan_data->speed_index < 0)
 		return fan_data->speed_index;

 	return 0;
 }

 static int gpio_fan_get_max_state(struct thermal_cooling_device *cdev,
 				  unsigned long *state)
 {
 	struct gpio_fan_data *fan_data = cdev->devdata;

 	if (!fan_data)
 		return -EINVAL;

 	*state = fan_data->num_speed - 1;
 	return 0;
 }

 static int gpio_fan_get_cur_state(struct thermal_cooling_device *cdev,
 				  unsigned long *state)
 {
 	struct gpio_fan_data *fan_data = cdev->devdata;

 	if (!fan_data)
 		return -EINVAL;

 	*state = fan_data->speed_index;
 	return 0;
 }

 static int gpio_fan_set_cur_state(struct thermal_cooling_device *cdev,
 				  unsigned long state)
 {
 	struct gpio_fan_data *fan_data = cdev->devdata;

 	if (!fan_data)
 		return -EINVAL;

 	if (state >= fan_data->num_speed)
 		return -EINVAL;

 	set_fan_speed(fan_data, state);
 	return 0;
 }

 static const struct thermal_cooling_device_ops gpio_fan_cool_ops = {
 	.get_max_state = gpio_fan_get_max_state,
 	.get_cur_state = gpio_fan_get_cur_state,
 	.set_cur_state = gpio_fan_set_cur_state,
 };

 /*
  * Translate OpenFirmware node properties into platform_data
  */
 static int gpio_fan_get_of_data(struct gpio_fan_data *fan_data)
 {
 	struct gpio_fan_speed *speed;
 	struct device *dev = fan_data->dev;
 	struct device_node *np = dev->of_node;
 	struct gpio_desc **gpios;
 	unsigned i;
 	u32 u;
 	struct property *prop;
 	const __be32 *p;

 	/* Alarm GPIO if one exists */
 	fan_data->alarm_gpio = devm_gpiod_get_optional(dev, "alarm", GPIOD_IN);
 	if (IS_ERR(fan_data->alarm_gpio))
 		return PTR_ERR(fan_data->alarm_gpio);

 	/* Fill GPIO pin array */
 	fan_data->num_gpios = gpiod_count(dev, NULL);
 	if (fan_data->num_gpios <= 0) {
 		if (fan_data->alarm_gpio)
 			return 0;
 		dev_err(dev, "DT properties empty / missing");
 		return -ENODEV;
 	}
 	gpios = devm_kcalloc(dev,
 			     fan_data->num_gpios, sizeof(struct gpio_desc *),
 			     GFP_KERNEL);
 	if (!gpios)
 		return -ENOMEM;
 	for (i = 0; i < fan_data->num_gpios; i++) {
 		gpios[i] = devm_gpiod_get_index(dev, NULL, i, GPIOD_ASIS);
 		if (IS_ERR(gpios[i]))
 			return PTR_ERR(gpios[i]);
 	}
 	fan_data->gpios = gpios;

 	/* Get number of RPM/ctrl_val pairs in speed map */
 	prop = of_find_property(np, "gpio-fan,speed-map", &i);
 	if (!prop) {
 		dev_err(dev, "gpio-fan,speed-map DT property missing");
 		return -ENODEV;
 	}
 	i = i / sizeof(u32);
 	if (i == 0 || i & 1) {
 		dev_err(dev, "gpio-fan,speed-map contains zero/odd number of entries");
 		return -ENODEV;
 	}
 	fan_data->num_speed = i / 2;

 	/*
 	 * Populate speed map
 	 * Speed map is in the form <RPM ctrl_val RPM ctrl_val ...>
 	 * this needs splitting into pairs to create gpio_fan_speed structs
 	 */
 	speed = devm_kcalloc(dev,
 			fan_data->num_speed, sizeof(struct gpio_fan_speed),
 			GFP_KERNEL);
 	if (!speed)
 		return -ENOMEM;
 	p = NULL;
 	for (i = 0; i < fan_data->num_speed; i++) {
 		p = of_prop_next_u32(prop, p, &u);
 		if (!p)
 			return -ENODEV;
 		speed[i].rpm = u;
 		p = of_prop_next_u32(prop, p, &u);
 		if (!p)
 			return -ENODEV;
 		speed[i].ctrl_val = u;
 	}
 	fan_data->speed = speed;

 	return 0;
 }

 static const struct of_device_id of_gpio_fan_match[] = {
 	{ .compatible = "gpio-fan", },
 	{},
 };
 MODULE_DEVICE_TABLE(of, of_gpio_fan_match);

 static void gpio_fan_stop(void *data)
 {
 	set_fan_speed(data, 0);
 }

 static int gpio_fan_probe(struct platform_device *pdev)
 {
 	int err;
 	struct gpio_fan_data *fan_data;
 	struct device *dev = &pdev->dev;
 	struct device_node *np = dev->of_node;

 	fan_data = devm_kzalloc(dev, sizeof(struct gpio_fan_data),
 				GFP_KERNEL);
 	if (!fan_data)
 		return -ENOMEM;

 	fan_data->dev = dev;
 	err = gpio_fan_get_of_data(fan_data);
 	if (err)
 		return err;

 	platform_set_drvdata(pdev, fan_data);
 	mutex_init(&fan_data->lock);

 	/* Configure control GPIOs if available. */
 	if (fan_data->gpios && fan_data->num_gpios > 0) {
 		if (!fan_data->speed || fan_data->num_speed <= 1)
 			return -EINVAL;
 		err = fan_ctrl_init(fan_data);
 		if (err)
 			return err;
 		err = devm_add_action_or_reset(dev, gpio_fan_stop, fan_data);
 		if (err)
 			return err;
 	}

 	/* Make this driver part of hwmon class. */
 	fan_data->hwmon_dev =
 		devm_hwmon_device_register_with_groups(dev,
 						       "gpio_fan", fan_data,
 						       gpio_fan_groups);
 	if (IS_ERR(fan_data->hwmon_dev))
 		return PTR_ERR(fan_data->hwmon_dev);

 	/* Configure alarm GPIO if available. */
 	if (fan_data->alarm_gpio) {
 		err = fan_alarm_init(fan_data);
 		if (err)
 			return err;
 	}

 	/* Optional cooling device register for Device tree platforms */
 	fan_data->cdev = devm_thermal_of_cooling_device_register(dev, np,
 				"gpio-fan", fan_data, &gpio_fan_cool_ops);

 	dev_info(dev, "GPIO fan initialized\n");

 	return 0;
 }

 static void gpio_fan_shutdown(struct platform_device *pdev)
 {
 	struct gpio_fan_data *fan_data = platform_get_drvdata(pdev);

 	if (fan_data->gpios)
 		set_fan_speed(fan_data, 0);
 }

 #ifdef CONFIG_PM_SLEEP
 static int gpio_fan_suspend(struct device *dev)
 {
 	struct gpio_fan_data *fan_data = dev_get_drvdata(dev);

 	if (fan_data->gpios) {
 		fan_data->resume_speed = fan_data->speed_index;
 		set_fan_speed(fan_data, 0);
 	}

 	return 0;
 }

 static int gpio_fan_resume(struct device *dev)
 {
 	struct gpio_fan_data *fan_data = dev_get_drvdata(dev);

 	if (fan_data->gpios)
 		set_fan_speed(fan_data, fan_data->resume_speed);

 	return 0;
 }

 static SIMPLE_DEV_PM_OPS(gpio_fan_pm, gpio_fan_suspend, gpio_fan_resume);
 #define GPIO_FAN_PM	(&gpio_fan_pm)
 #else
 #define GPIO_FAN_PM	NULL
 #endif

 static struct platform_driver gpio_fan_driver = {
 	.probe		= gpio_fan_probe,
 	.shutdown	= gpio_fan_shutdown,
 	.driver	= {
 		.name	= "gpio-fan",
 		.pm	= GPIO_FAN_PM,
 		.of_match_table = of_match_ptr(of_gpio_fan_match),
 	},
 };

 module_platform_driver(gpio_fan_driver);

 MODULE_AUTHOR("Simon Guinot <sguinot@lacie.com>");
 MODULE_DESCRIPTION("GPIO FAN driver");
 MODULE_LICENSE("GPL");
 MODULE_ALIAS("platform:gpio-fan");
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	* gpio-fan.c - Hwmon driver for fans connected to GPIO lines.
	*
	* Copyright (C) 2010 LaCie
	*
	* Author: Simon Guinot <sguinot@lacie.com>
	*/

	#include <linux/module.h>
	#include <linux/init.h>
	#include <linux/slab.h>
	#include <linux/interrupt.h>
	#include <linux/irq.h>
	#include <linux/platform_device.h>
	#include <linux/err.h>
	#include <linux/mutex.h>
	#include <linux/hwmon.h>
	#include <linux/gpio/consumer.h>
	#include <linux/of.h>
	#include <linux/of_platform.h>
	#include <linux/thermal.h>

	struct gpio_fan_speed {
	int rpm;
	int ctrl_val;
	};

	struct gpio_fan_data {
	struct device *dev;
	struct device *hwmon_dev;
	/* Cooling device if any */
	struct thermal_cooling_device *cdev;
	struct mutex lock; /* lock GPIOs operations. */
	int num_gpios;
	struct gpio_desc **gpios;
	int num_speed;
	struct gpio_fan_speed *speed;
	int speed_index;
	#ifdef CONFIG_PM_SLEEP
	int resume_speed;
	#endif
	bool pwm_enable;
	struct gpio_desc *alarm_gpio;
	struct work_struct alarm_work;
	};

	/*
	* Alarm GPIO.
	*/

	static void fan_alarm_notify(struct work_struct *ws)
	{
	struct gpio_fan_data *fan_data =
	container_of(ws, struct gpio_fan_data, alarm_work);

	sysfs_notify(&fan_data->hwmon_dev->kobj, NULL, "fan1_alarm");
	kobject_uevent(&fan_data->hwmon_dev->kobj, KOBJ_CHANGE);
	}

	static irqreturn_t fan_alarm_irq_handler(int irq, void *dev_id)
	{
	struct gpio_fan_data *fan_data = dev_id;

	schedule_work(&fan_data->alarm_work);

	return IRQ_NONE;
	}

	static ssize_t fan1_alarm_show(struct device *dev,
	struct device_attribute attr, char buf)
	{
	struct gpio_fan_data *fan_data = dev_get_drvdata(dev);

	return sprintf(buf, "%d\n",
	gpiod_get_value_cansleep(fan_data->alarm_gpio));
	}

	static DEVICE_ATTR_RO(fan1_alarm);

	static int fan_alarm_init(struct gpio_fan_data *fan_data)
	{
	int alarm_irq;
	struct device *dev = fan_data->dev;

	/*
	* If the alarm GPIO don't support interrupts, just leave
	* without initializing the fail notification support.
	*/
	alarm_irq = gpiod_to_irq(fan_data->alarm_gpio);
	if (alarm_irq <= 0)
	return 0;

	INIT_WORK(&fan_data->alarm_work, fan_alarm_notify);
	irq_set_irq_type(alarm_irq, IRQ_TYPE_EDGE_BOTH);
	return devm_request_irq(dev, alarm_irq, fan_alarm_irq_handler,
	IRQF_SHARED, "GPIO fan alarm", fan_data);
	}

	/*
	* Control GPIOs.
	*/

	/* Must be called with fan_data->lock held, except during initialization. */
	static void __set_fan_ctrl(struct gpio_fan_data *fan_data, int ctrl_val)
	{
	int i;

	for (i = 0; i < fan_data->num_gpios; i++)
	gpiod_set_value_cansleep(fan_data->gpios[i],
	(ctrl_val >> i) & 1);
	}

	static int __get_fan_ctrl(struct gpio_fan_data *fan_data)
	{
	int i;
	int ctrl_val = 0;

	for (i = 0; i < fan_data->num_gpios; i++) {
	int value;

	value = gpiod_get_value_cansleep(fan_data->gpios[i]);
	ctrl_val \|= (value << i);
	}
	return ctrl_val;
	}

	/* Must be called with fan_data->lock held, except during initialization. */
	static void set_fan_speed(struct gpio_fan_data *fan_data, int speed_index)
	{
	if (fan_data->speed_index == speed_index)
	return;

	__set_fan_ctrl(fan_data, fan_data->speed[speed_index].ctrl_val);
	fan_data->speed_index = speed_index;
	}

	static int get_fan_speed_index(struct gpio_fan_data *fan_data)
	{
	int ctrl_val = __get_fan_ctrl(fan_data);
	int i;

	for (i = 0; i < fan_data->num_speed; i++)
	if (fan_data->speed[i].ctrl_val == ctrl_val)
	return i;

	dev_warn(fan_data->dev,
	"missing speed array entry for GPIO value 0x%x\n", ctrl_val);

	return -ENODEV;
	}

	static int rpm_to_speed_index(struct gpio_fan_data *fan_data, unsigned long rpm)
	{
	struct gpio_fan_speed *speed = fan_data->speed;
	int i;

	for (i = 0; i < fan_data->num_speed; i++)
	if (speed[i].rpm >= rpm)
	return i;

	return fan_data->num_speed - 1;
	}

	static ssize_t pwm1_show(struct device dev, struct device_attribute attr,
	char *buf)
	{
	struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
	u8 pwm = fan_data->speed_index * 255 / (fan_data->num_speed - 1);

	return sprintf(buf, "%d\n", pwm);
	}

	static ssize_t pwm1_store(struct device dev, struct device_attribute attr,
	const char *buf, size_t count)
	{
	struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
	unsigned long pwm;
	int speed_index;
	int ret = count;

	if (kstrtoul(buf, 10, &pwm) \|\| pwm > 255)
	return -EINVAL;

	mutex_lock(&fan_data->lock);

	if (!fan_data->pwm_enable) {
	ret = -EPERM;
	goto exit_unlock;
	}

	speed_index = DIV_ROUND_UP(pwm * (fan_data->num_speed - 1), 255);
	set_fan_speed(fan_data, speed_index);

	exit_unlock:
	mutex_unlock(&fan_data->lock);

	return ret;
	}

	static ssize_t pwm1_enable_show(struct device *dev,
	struct device_attribute attr, char buf)
	{
	struct gpio_fan_data *fan_data = dev_get_drvdata(dev);

	return sprintf(buf, "%d\n", fan_data->pwm_enable);
	}

	static ssize_t pwm1_enable_store(struct device *dev,
	struct device_attribute *attr,
	const char *buf, size_t count)
	{
	struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
	unsigned long val;

	if (kstrtoul(buf, 10, &val) \|\| val > 1)
	return -EINVAL;

	if (fan_data->pwm_enable == val)
	return count;

	mutex_lock(&fan_data->lock);

	fan_data->pwm_enable = val;

	/* Disable manual control mode: set fan at full speed. */
	if (val == 0)
	set_fan_speed(fan_data, fan_data->num_speed - 1);

	mutex_unlock(&fan_data->lock);

	return count;
	}

	static ssize_t pwm1_mode_show(struct device *dev,
	struct device_attribute attr, char buf)
	{
	return sprintf(buf, "0\n");
	}

	static ssize_t fan1_min_show(struct device *dev,
	struct device_attribute attr, char buf)
	{
	struct gpio_fan_data *fan_data = dev_get_drvdata(dev);

	return sprintf(buf, "%d\n", fan_data->speed[0].rpm);
	}

	static ssize_t fan1_max_show(struct device *dev,
	struct device_attribute attr, char buf)
	{
	struct gpio_fan_data *fan_data = dev_get_drvdata(dev);

	return sprintf(buf, "%d\n",
	fan_data->speed[fan_data->num_speed - 1].rpm);
	}

	static ssize_t fan1_input_show(struct device *dev,
	struct device_attribute attr, char buf)
	{
	struct gpio_fan_data *fan_data = dev_get_drvdata(dev);

	return sprintf(buf, "%d\n", fan_data->speed[fan_data->speed_index].rpm);
	}

	static ssize_t set_rpm(struct device dev, struct device_attribute attr,
	const char *buf, size_t count)
	{
	struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
	unsigned long rpm;
	int ret = count;

	if (kstrtoul(buf, 10, &rpm))
	return -EINVAL;

	mutex_lock(&fan_data->lock);

	if (!fan_data->pwm_enable) {
	ret = -EPERM;
	goto exit_unlock;
	}

	set_fan_speed(fan_data, rpm_to_speed_index(fan_data, rpm));

	exit_unlock:
	mutex_unlock(&fan_data->lock);

	return ret;
	}

	static DEVICE_ATTR_RW(pwm1);
	static DEVICE_ATTR_RW(pwm1_enable);
	static DEVICE_ATTR_RO(pwm1_mode);
	static DEVICE_ATTR_RO(fan1_min);
	static DEVICE_ATTR_RO(fan1_max);
	static DEVICE_ATTR_RO(fan1_input);
	static DEVICE_ATTR(fan1_target, 0644, fan1_input_show, set_rpm);

	static umode_t gpio_fan_is_visible(struct kobject *kobj,
	struct attribute *attr, int index)
	{
	struct device *dev = container_of(kobj, struct device, kobj);
	struct gpio_fan_data *data = dev_get_drvdata(dev);

	if (index == 0 && !data->alarm_gpio)
	return 0;
	if (index > 0 && !data->gpios)
	return 0;

	return attr->mode;
	}

	static struct attribute *gpio_fan_attributes[] = {
	&dev_attr_fan1_alarm.attr, /* 0 */
	&dev_attr_pwm1.attr, /* 1 */
	&dev_attr_pwm1_enable.attr,
	&dev_attr_pwm1_mode.attr,
	&dev_attr_fan1_input.attr,
	&dev_attr_fan1_target.attr,
	&dev_attr_fan1_min.attr,
	&dev_attr_fan1_max.attr,
	NULL
	};

	static const struct attribute_group gpio_fan_group = {
	.attrs = gpio_fan_attributes,
	.is_visible = gpio_fan_is_visible,
	};

	static const struct attribute_group *gpio_fan_groups[] = {
	&gpio_fan_group,
	NULL
	};

	static int fan_ctrl_init(struct gpio_fan_data *fan_data)
	{
	int num_gpios = fan_data->num_gpios;
	struct gpio_desc **gpios = fan_data->gpios;
	int i, err;

	for (i = 0; i < num_gpios; i++) {
	/*
	* The GPIO descriptors were retrieved with GPIOD_ASIS so here
	* we set the GPIO into output mode, carefully preserving the
	* current value by setting it to whatever it is already set
	* (no surprise changes in default fan speed).
	*/
	err = gpiod_direction_output(gpios[i],
	gpiod_get_value_cansleep(gpios[i]));
	if (err)
	return err;
	}

	fan_data->pwm_enable = true; /* Enable manual fan speed control. */
	fan_data->speed_index = get_fan_speed_index(fan_data);
	if (fan_data->speed_index < 0)
	return fan_data->speed_index;

	return 0;
	}

	static int gpio_fan_get_max_state(struct thermal_cooling_device *cdev,
	unsigned long *state)
	{
	struct gpio_fan_data *fan_data = cdev->devdata;

	if (!fan_data)
	return -EINVAL;

	*state = fan_data->num_speed - 1;
	return 0;
	}

	static int gpio_fan_get_cur_state(struct thermal_cooling_device *cdev,
	unsigned long *state)
	{
	struct gpio_fan_data *fan_data = cdev->devdata;

	if (!fan_data)
	return -EINVAL;

	*state = fan_data->speed_index;
	return 0;
	}

	static int gpio_fan_set_cur_state(struct thermal_cooling_device *cdev,
	unsigned long state)
	{
	struct gpio_fan_data *fan_data = cdev->devdata;

	if (!fan_data)
	return -EINVAL;

	if (state >= fan_data->num_speed)
	return -EINVAL;

	set_fan_speed(fan_data, state);
	return 0;
	}

	static const struct thermal_cooling_device_ops gpio_fan_cool_ops = {
	.get_max_state = gpio_fan_get_max_state,
	.get_cur_state = gpio_fan_get_cur_state,
	.set_cur_state = gpio_fan_set_cur_state,
	};

	/*
	* Translate OpenFirmware node properties into platform_data
	*/
	static int gpio_fan_get_of_data(struct gpio_fan_data *fan_data)
	{
	struct gpio_fan_speed *speed;
	struct device *dev = fan_data->dev;
	struct device_node *np = dev->of_node;
	struct gpio_desc **gpios;
	unsigned i;
	u32 u;
	struct property *prop;
	const __be32 *p;

	/* Alarm GPIO if one exists */
	fan_data->alarm_gpio = devm_gpiod_get_optional(dev, "alarm", GPIOD_IN);
	if (IS_ERR(fan_data->alarm_gpio))
	return PTR_ERR(fan_data->alarm_gpio);

	/* Fill GPIO pin array */
	fan_data->num_gpios = gpiod_count(dev, NULL);
	if (fan_data->num_gpios <= 0) {
	if (fan_data->alarm_gpio)
	return 0;
	dev_err(dev, "DT properties empty / missing");
	return -ENODEV;
	}
	gpios = devm_kcalloc(dev,
	fan_data->num_gpios, sizeof(struct gpio_desc *),
	GFP_KERNEL);
	if (!gpios)
	return -ENOMEM;
	for (i = 0; i < fan_data->num_gpios; i++) {
	gpios[i] = devm_gpiod_get_index(dev, NULL, i, GPIOD_ASIS);
	if (IS_ERR(gpios[i]))
	return PTR_ERR(gpios[i]);
	}
	fan_data->gpios = gpios;

	/* Get number of RPM/ctrl_val pairs in speed map */
	prop = of_find_property(np, "gpio-fan,speed-map", &i);
	if (!prop) {
	dev_err(dev, "gpio-fan,speed-map DT property missing");
	return -ENODEV;
	}
	i = i / sizeof(u32);
	if (i == 0 \|\| i & 1) {
	dev_err(dev, "gpio-fan,speed-map contains zero/odd number of entries");
	return -ENODEV;
	}
	fan_data->num_speed = i / 2;

	/*
	* Populate speed map
	* Speed map is in the form <RPM ctrl_val RPM ctrl_val ...>
	* this needs splitting into pairs to create gpio_fan_speed structs
	*/
	speed = devm_kcalloc(dev,
	fan_data->num_speed, sizeof(struct gpio_fan_speed),
	GFP_KERNEL);
	if (!speed)
	return -ENOMEM;
	p = NULL;
	for (i = 0; i < fan_data->num_speed; i++) {
	p = of_prop_next_u32(prop, p, &u);
	if (!p)
	return -ENODEV;
	speed[i].rpm = u;
	p = of_prop_next_u32(prop, p, &u);
	if (!p)
	return -ENODEV;
	speed[i].ctrl_val = u;
	}
	fan_data->speed = speed;

	return 0;
	}

	static const struct of_device_id of_gpio_fan_match[] = {
	{ .compatible = "gpio-fan", },
	{},
	};
	MODULE_DEVICE_TABLE(of, of_gpio_fan_match);

	static void gpio_fan_stop(void *data)
	{
	set_fan_speed(data, 0);
	}

	static int gpio_fan_probe(struct platform_device *pdev)
	{
	int err;
	struct gpio_fan_data *fan_data;
	struct device *dev = &pdev->dev;
	struct device_node *np = dev->of_node;

	fan_data = devm_kzalloc(dev, sizeof(struct gpio_fan_data),
	GFP_KERNEL);
	if (!fan_data)
	return -ENOMEM;

	fan_data->dev = dev;
	err = gpio_fan_get_of_data(fan_data);
	if (err)
	return err;

	platform_set_drvdata(pdev, fan_data);
	mutex_init(&fan_data->lock);

	/* Configure control GPIOs if available. */
	if (fan_data->gpios && fan_data->num_gpios > 0) {
	if (!fan_data->speed \|\| fan_data->num_speed <= 1)
	return -EINVAL;
	err = fan_ctrl_init(fan_data);
	if (err)
	return err;
	err = devm_add_action_or_reset(dev, gpio_fan_stop, fan_data);
	if (err)
	return err;
	}

	/* Make this driver part of hwmon class. */
	fan_data->hwmon_dev =
	devm_hwmon_device_register_with_groups(dev,
	"gpio_fan", fan_data,
	gpio_fan_groups);
	if (IS_ERR(fan_data->hwmon_dev))
	return PTR_ERR(fan_data->hwmon_dev);

	/* Configure alarm GPIO if available. */
	if (fan_data->alarm_gpio) {
	err = fan_alarm_init(fan_data);
	if (err)
	return err;
	}

	/* Optional cooling device register for Device tree platforms */
	fan_data->cdev = devm_thermal_of_cooling_device_register(dev, np,
	"gpio-fan", fan_data, &gpio_fan_cool_ops);

	dev_info(dev, "GPIO fan initialized\n");

	return 0;
	}

	static void gpio_fan_shutdown(struct platform_device *pdev)
	{
	struct gpio_fan_data *fan_data = platform_get_drvdata(pdev);

	if (fan_data->gpios)
	set_fan_speed(fan_data, 0);
	}

	#ifdef CONFIG_PM_SLEEP
	static int gpio_fan_suspend(struct device *dev)
	{
	struct gpio_fan_data *fan_data = dev_get_drvdata(dev);

	if (fan_data->gpios) {
	fan_data->resume_speed = fan_data->speed_index;
	set_fan_speed(fan_data, 0);
	}

	return 0;
	}

	static int gpio_fan_resume(struct device *dev)
	{
	struct gpio_fan_data *fan_data = dev_get_drvdata(dev);

	if (fan_data->gpios)
	set_fan_speed(fan_data, fan_data->resume_speed);

	return 0;
	}

	static SIMPLE_DEV_PM_OPS(gpio_fan_pm, gpio_fan_suspend, gpio_fan_resume);
	#define GPIO_FAN_PM (&gpio_fan_pm)
	#else
	#define GPIO_FAN_PM NULL
	#endif

	static struct platform_driver gpio_fan_driver = {
	.probe = gpio_fan_probe,
	.shutdown = gpio_fan_shutdown,
	.driver = {
	.name = "gpio-fan",
	.pm = GPIO_FAN_PM,
	.of_match_table = of_match_ptr(of_gpio_fan_match),
	},
	};

	module_platform_driver(gpio_fan_driver);

	MODULE_AUTHOR("Simon Guinot <sguinot@lacie.com>");
	MODULE_DESCRIPTION("GPIO FAN driver");
	MODULE_LICENSE("GPL");
	MODULE_ALIAS("platform:gpio-fan");