(gpio-fan): Add thermal control hooks

Allow gpio-fan to be used as thermal cooling device for platforms that
use GPIO maps to control fans.

As part of this change, we make the shutdown and remove logic the same
as well.

Signed-off-by: Nishanth Menon <nm@ti.com>
Acked-by: Eduardo Valentin <edubezval@gmail.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Documentation/devicetree/bindings/gpio/gpio-fan.txt

@@ -11,6 +11,9 @@ Optional properties:
   must have the RPM values in ascending order.
 - alarm-gpios: This pin going active indicates something is wrong with
   the fan, and a udev event will be fired.
+- cooling-cells: If used as a cooling device, must be <2>
+  Also see: Documentation/devicetree/bindings/thermal/thermal.txt
+  min and max states are derived from the speed-map of the fan.
 
 Note: At least one the "gpios" or "alarm-gpios" properties must be set.
 
@@ -25,3 +28,13 @@ Examples:
 				      6000 2>;
 		alarm-gpios = <&gpio1 15 1>;
 	};
+	gpio_fan_cool: gpio_fan {
+		compatible = "gpio-fan";
+		gpios = <&gpio2 14 1
+			 &gpio2 13 1>;
+		gpio-fan,speed-map =	<0    0>,
+					<3000 1>,
+					<6000 2>;
+		alarm-gpios = <&gpio2 15 1>;
+		#cooling-cells = <2>; /* min followed by max */
+	};

drivers/hwmon/gpio-fan.c

@@ -34,10 +34,13 @@
 #include <linux/of.h>
 #include <linux/of_platform.h>
 #include <linux/of_gpio.h>
+#include <linux/thermal.h>
 
 struct gpio_fan_data {
 	struct platform_device	*pdev;
 	struct device		*hwmon_dev;
+	/* Cooling device if any */
+	struct thermal_cooling_device *cdev;
 	struct mutex		lock; /* lock GPIOs operations. */
 	int			num_ctrl;
 	unsigned		*ctrl;
@@ -387,6 +390,53 @@ static int fan_ctrl_init(struct gpio_fan_data *fan_data,
 	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;
+	int r;
+
+	if (!fan_data)
+		return -EINVAL;
+
+	r = get_fan_speed_index(fan_data);
+	if (r < 0)
+		return r;
+
+	*state = r;
+	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;
+
+	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,
+};
+
 #ifdef CONFIG_OF_GPIO
 /*
  * Translate OpenFirmware node properties into platform_data
@@ -497,6 +547,11 @@ static int gpio_fan_probe(struct platform_device *pdev)
 	struct gpio_fan_data *fan_data;
 	struct gpio_fan_platform_data *pdata = dev_get_platdata(&pdev->dev);
 
+	fan_data = devm_kzalloc(&pdev->dev, sizeof(struct gpio_fan_data),
+				GFP_KERNEL);
+	if (!fan_data)
+		return -ENOMEM;
+
 #ifdef CONFIG_OF_GPIO
 	if (!pdata) {
 		pdata = devm_kzalloc(&pdev->dev,
@@ -508,17 +563,20 @@ static int gpio_fan_probe(struct platform_device *pdev)
 		err = gpio_fan_get_of_pdata(&pdev->dev, pdata);
 		if (err)
 			return err;
+		/* Optional cooling device register for Device tree platforms */
+		fan_data->cdev =
+			thermal_of_cooling_device_register(pdev->dev.of_node,
+							   "gpio-fan", fan_data,
+							   &gpio_fan_cool_ops);
 	}
 #else /* CONFIG_OF_GPIO */
 	if (!pdata)
 		return -EINVAL;
+	/* Optional cooling device register for non Device tree platforms */
+	fan_data->cdev = thermal_cooling_device_register("gpio-fan", fan_data,
+							 &gpio_fan_cool_ops);
 #endif /* CONFIG_OF_GPIO */
 
-	fan_data = devm_kzalloc(&pdev->dev, sizeof(struct gpio_fan_data),
-				GFP_KERNEL);
-	if (!fan_data)
-		return -ENOMEM;
-
 	fan_data->pdev = pdev;
 	platform_set_drvdata(pdev, fan_data);
 	mutex_init(&fan_data->lock);
@@ -552,12 +610,22 @@ static int gpio_fan_probe(struct platform_device *pdev)
 	return 0;
 }
 
-static void gpio_fan_shutdown(struct platform_device *pdev)
+static int gpio_fan_remove(struct platform_device *pdev)
 {
-	struct gpio_fan_data *fan_data = dev_get_drvdata(&pdev->dev);
+	struct gpio_fan_data *fan_data = platform_get_drvdata(pdev);
+
+	if (!IS_ERR(fan_data->cdev))
+		thermal_cooling_device_unregister(fan_data->cdev);
 
 	if (fan_data->ctrl)
 		set_fan_speed(fan_data, 0);
+
+	return 0;
+}
+
+static void gpio_fan_shutdown(struct platform_device *pdev)
+{
+	gpio_fan_remove(pdev);
 }
 
 #ifdef CONFIG_PM_SLEEP
@@ -591,6 +659,7 @@ static SIMPLE_DEV_PM_OPS(gpio_fan_pm, gpio_fan_suspend, gpio_fan_resume);
 
 static struct platform_driver gpio_fan_driver = {
 	.probe		= gpio_fan_probe,
+	.remove		= gpio_fan_remove,
 	.shutdown	= gpio_fan_shutdown,
 	.driver	= {
 		.name	= "gpio-fan",