[PATCH] LED: add LED class

Add the foundations of a new LEDs subsystem.  This patch adds a class which
presents LED devices within sysfs and allows their brightness to be
controlled.
Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/arm/Kconfig

@@ -839,6 +839,8 @@ source "drivers/misc/Kconfig"
 
 source "drivers/mfd/Kconfig"
 
+source "drivers/leds/Kconfig"
+
 source "drivers/media/Kconfig"
 
 source "drivers/video/Kconfig"

drivers/Kconfig

@@ -64,6 +64,8 @@ source "drivers/usb/Kconfig"
 
 source "drivers/mmc/Kconfig"
 
+source "drivers/leds/Kconfig"
+
 source "drivers/infiniband/Kconfig"
 
 source "drivers/sn/Kconfig"

drivers/Makefile

@@ -69,6 +69,7 @@ obj-$(CONFIG_MCA)		+= mca/
 obj-$(CONFIG_EISA)		+= eisa/
 obj-$(CONFIG_CPU_FREQ)		+= cpufreq/
 obj-$(CONFIG_MMC)		+= mmc/
+obj-$(CONFIG_NEW_LEDS)		+= leds/
 obj-$(CONFIG_INFINIBAND)	+= infiniband/
 obj-$(CONFIG_SGI_SN)		+= sn/
 obj-y				+= firmware/

drivers/leds/Kconfig

+
+menu "LED devices"
+
+config NEW_LEDS
+	bool "LED Support"
+	help
+	  Say Y to enable Linux LED support.  This is not related to standard
+	  keyboard LEDs which are controlled via the input system.
+
+config LEDS_CLASS
+	tristate "LED Class Support"
+	depends NEW_LEDS
+	help
+	  This option enables the led sysfs class in /sys/class/leds.  You'll
+	  need this to do anything useful with LEDs.  If unsure, say N.
+
+endmenu
+

drivers/leds/Makefile

+
+# LED Core
+obj-$(CONFIG_NEW_LEDS)			+= led-core.o
+obj-$(CONFIG_LEDS_CLASS)		+= led-class.o

drivers/leds/led-class.c

+/*
+ * LED Class Core
+ *
+ * Copyright (C) 2005 John Lenz <lenz@cs.wisc.edu>
+ * Copyright (C) 2005-2006 Richard Purdie <rpurdie@openedhand.com>
+ *
+ * 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/config.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/list.h>
+#include <linux/spinlock.h>
+#include <linux/device.h>
+#include <linux/sysdev.h>
+#include <linux/timer.h>
+#include <linux/err.h>
+#include <linux/leds.h>
+#include "leds.h"
+
+static struct class *leds_class;
+
+static ssize_t led_brightness_show(struct class_device *dev, char *buf)
+{
+	struct led_classdev *led_cdev = class_get_devdata(dev);
+	ssize_t ret = 0;
+
+	/* no lock needed for this */
+	sprintf(buf, "%u\n", led_cdev->brightness);
+	ret = strlen(buf) + 1;
+
+	return ret;
+}
+
+static ssize_t led_brightness_store(struct class_device *dev,
+				const char *buf, size_t size)
+{
+	struct led_classdev *led_cdev = class_get_devdata(dev);
+	ssize_t ret = -EINVAL;
+	char *after;
+	unsigned long state = simple_strtoul(buf, &after, 10);
+
+	if (after - buf > 0) {
+		ret = after - buf;
+		led_set_brightness(led_cdev, state);
+	}
+
+	return ret;
+}
+
+static CLASS_DEVICE_ATTR(brightness, 0644, led_brightness_show,
+			led_brightness_store);
+
+/**
+ * led_classdev_suspend - suspend an led_classdev.
+ * @led_cdev: the led_classdev to suspend.
+ */
+void led_classdev_suspend(struct led_classdev *led_cdev)
+{
+	led_cdev->flags |= LED_SUSPENDED;
+	led_cdev->brightness_set(led_cdev, 0);
+}
+EXPORT_SYMBOL_GPL(led_classdev_suspend);
+
+/**
+ * led_classdev_resume - resume an led_classdev.
+ * @led_cdev: the led_classdev to resume.
+ */
+void led_classdev_resume(struct led_classdev *led_cdev)
+{
+	led_cdev->brightness_set(led_cdev, led_cdev->brightness);
+	led_cdev->flags &= ~LED_SUSPENDED;
+}
+EXPORT_SYMBOL_GPL(led_classdev_resume);
+
+/**
+ * led_classdev_register - register a new object of led_classdev class.
+ * @dev: The device to register.
+ * @led_cdev: the led_classdev structure for this device.
+ */
+int led_classdev_register(struct device *parent, struct led_classdev *led_cdev)
+{
+	led_cdev->class_dev = class_device_create(leds_class, NULL, 0,
+						parent, "%s", led_cdev->name);
+	if (unlikely(IS_ERR(led_cdev->class_dev)))
+		return PTR_ERR(led_cdev->class_dev);
+
+	class_set_devdata(led_cdev->class_dev, led_cdev);
+
+	/* register the attributes */
+	class_device_create_file(led_cdev->class_dev,
+				&class_device_attr_brightness);
+
+	/* add to the list of leds */
+	write_lock(&leds_list_lock);
+	list_add_tail(&led_cdev->node, &leds_list);
+	write_unlock(&leds_list_lock);
+
+	printk(KERN_INFO "Registered led device: %s\n",
+			led_cdev->class_dev->class_id);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(led_classdev_register);
+
+/**
+ * led_classdev_unregister - unregisters a object of led_properties class.
+ * @led_cdev: the led device to unreigister
+ *
+ * Unregisters a previously registered via led_classdev_register object.
+ */
+void led_classdev_unregister(struct led_classdev *led_cdev)
+{
+	class_device_remove_file(led_cdev->class_dev,
+				&class_device_attr_brightness);
+
+	class_device_unregister(led_cdev->class_dev);
+
+	write_lock(&leds_list_lock);
+	list_del(&led_cdev->node);
+	write_unlock(&leds_list_lock);
+}
+EXPORT_SYMBOL_GPL(led_classdev_unregister);
+
+static int __init leds_init(void)
+{
+	leds_class = class_create(THIS_MODULE, "leds");
+	if (IS_ERR(leds_class))
+		return PTR_ERR(leds_class);
+	return 0;
+}
+
+static void __exit leds_exit(void)
+{
+	class_destroy(leds_class);
+}
+
+subsys_initcall(leds_init);
+module_exit(leds_exit);
+
+MODULE_AUTHOR("John Lenz, Richard Purdie");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("LED Class Interface");

drivers/leds/led-core.c

+/*
+ * LED Class Core
+ *
+ * Copyright 2005-2006 Openedhand Ltd.
+ *
+ * Author: Richard Purdie <rpurdie@openedhand.com>
+ *
+ * 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/list.h>
+#include <linux/module.h>
+#include <linux/spinlock.h>
+#include <linux/leds.h>
+#include "leds.h"
+
+rwlock_t leds_list_lock = RW_LOCK_UNLOCKED;
+LIST_HEAD(leds_list);
+
+EXPORT_SYMBOL_GPL(leds_list);
+EXPORT_SYMBOL_GPL(leds_list_lock);

drivers/leds/leds.h

+/*
+ * LED Core
+ *
+ * Copyright 2005 Openedhand Ltd.
+ *
+ * Author: Richard Purdie <rpurdie@openedhand.com>
+ *
+ * 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.
+ *
+ */
+#ifndef __LEDS_H_INCLUDED
+#define __LEDS_H_INCLUDED
+
+#include <linux/leds.h>
+
+static inline void led_set_brightness(struct led_classdev *led_cdev,
+					enum led_brightness value)
+{
+	if (value > LED_FULL)
+		value = LED_FULL;
+	led_cdev->brightness = value;
+	if (!(led_cdev->flags & LED_SUSPENDED))
+		led_cdev->brightness_set(led_cdev, value);
+}
+
+extern rwlock_t leds_list_lock;
+extern struct list_head leds_list;
+
+#endif	/* __LEDS_H_INCLUDED */

include/linux/leds.h

+/*
+ * Driver model for leds and led triggers
+ *
+ * Copyright (C) 2005 John Lenz <lenz@cs.wisc.edu>
+ * Copyright (C) 2005 Richard Purdie <rpurdie@openedhand.com>
+ *
+ * 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.
+ *
+ */
+#ifndef __LINUX_LEDS_H_INCLUDED
+#define __LINUX_LEDS_H_INCLUDED
+
+struct device;
+struct class_device;
+/*
+ * LED Core
+ */
+
+enum led_brightness {
+	LED_OFF = 0,
+	LED_HALF = 127,
+	LED_FULL = 255,
+};
+
+struct led_classdev {
+	const char *name;
+	int brightness;
+	int flags;
+#define LED_SUSPENDED       (1 << 0)
+
+	/* A function to set the brightness of the led */
+	void (*brightness_set)(struct led_classdev *led_cdev,
+				enum led_brightness brightness);
+
+	struct class_device *class_dev;
+	/* LED Device linked list */
+	struct list_head node;
+
+	/* Trigger data */
+	char *default_trigger;
+};
+
+extern int led_classdev_register(struct device *parent,
+				struct led_classdev *led_cdev);
+extern void led_classdev_unregister(struct led_classdev *led_cdev);
+extern void led_classdev_suspend(struct led_classdev *led_cdev);
+extern void led_classdev_resume(struct led_classdev *led_cdev);
+
+#endif		/* __LINUX_LEDS_H_INCLUDED */