[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>

1 files changed, 147 insertions, 0 deletions

diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
new file mode 100644
index 000000000000..0292df4101ba
--- /dev/null
+++ b/drivers/leds/led-class.c
@@ -0,0 +1,147 @@
+/*
+ * 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");