hwmon: add generic GPIO fan driver

This patch adds hwmon support for fans connected to GPIO lines.

Platform specific information such as GPIO pinout and speed conversion array
(rpm from/to GPIO value) are passed to the driver via platform_data.
Signed-off-by: Simon Guinot <sguinot@lacie.com>
Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>

drivers/hwmon/Kconfig

@@ -399,6 +399,15 @@ config SENSORS_GL520SM
 	  This driver can also be built as a module.  If so, the module
 	  will be called gl520sm.
 
+config SENSORS_GPIO_FAN
+	tristate "GPIO fan"
+	depends on GENERIC_GPIO
+	help
+	  If you say yes here you get support for fans connected to GPIO lines.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called gpio-fan.
+
 config SENSORS_CORETEMP
 	tristate "Intel Core/Core2/Atom temperature sensor"
 	depends on X86 && PCI && EXPERIMENTAL

drivers/hwmon/Makefile

@@ -51,6 +51,7 @@ obj-$(CONFIG_SENSORS_FSCHMD)	+= fschmd.o
 obj-$(CONFIG_SENSORS_G760A)	+= g760a.o
 obj-$(CONFIG_SENSORS_GL518SM)	+= gl518sm.o
 obj-$(CONFIG_SENSORS_GL520SM)	+= gl520sm.o
+obj-$(CONFIG_SENSORS_GPIO_FAN)	+= gpio-fan.o
 obj-$(CONFIG_SENSORS_ULTRA45)	+= ultra45_env.o
 obj-$(CONFIG_SENSORS_I5K_AMB)	+= i5k_amb.o
 obj-$(CONFIG_SENSORS_IBMAEM)	+= ibmaem.o

include/linux/gpio-fan.h

+/*
+ * include/linux/gpio-fan.h
+ *
+ * Platform data structure for GPIO fan driver
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2.  This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#ifndef __LINUX_GPIO_FAN_H
+#define __LINUX_GPIO_FAN_H
+
+struct gpio_fan_alarm {
+	unsigned	gpio;
+	unsigned	active_low;
+};
+
+struct gpio_fan_speed {
+	int rpm;
+	int ctrl_val;
+};
+
+struct gpio_fan_platform_data {
+	int			num_ctrl;
+	unsigned		*ctrl;	/* fan control GPIOs. */
+	struct gpio_fan_alarm	*alarm;	/* fan alarm GPIO. */
+	/*
+	 * Speed conversion array: rpm from/to GPIO bit field.
+	 * This array _must_ be sorted in ascending rpm order.
+	 */
+	int			num_speed;
+	struct gpio_fan_speed	*speed;
+};
+
+#endif /* __LINUX_GPIO_FAN_H */