[RFC PATCH 1/8] LED: Add LED Class

[Richard Purdie <rpurdie@rpsys.net>]

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>
Acked-by: Pavel Machek <pavel@suse.cz>

Index: linux-2.6.15-rc2/drivers/leds/Kconfig
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6.15-rc2/drivers/leds/Kconfig	2005-12-05 11:29:19.000000000 +0000
@@ -0,0 +1,18 @@
+
+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
+
Index: linux-2.6.15-rc2/drivers/leds/Makefile
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6.15-rc2/drivers/leds/Makefile	2005-12-05 11:29:19.000000000 +0000
@@ -0,0 +1,4 @@
+
+# LED Core
+obj-$(CONFIG_NEW_LEDS)			+= led_core.o
+obj-$(CONFIG_LEDS_CLASS)		+= led_class.o
Index: linux-2.6.15-rc2/include/linux/leds.h
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6.15-rc2/include/linux/leds.h	2005-12-05 11:29:19.000000000 +0000
@@ -0,0 +1,43 @@
+/*
+ * 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.
+ *
+ */
+
+struct device;
+struct class_device;
+/*
+ * LED Core
+ */
+struct led_device {
+	char *name;
+	int brightness;
+	int flags;
+#define LED_SUSPENDED       (1 << 0)
+
+	/* A function to set the brightness of the led.
+	 * Values are between 0-100 */
+	void (*brightness_set)(struct led_device *led_dev, int value);
+
+	struct class_device *class_dev;
+	/* LED Device linked list */
+	struct list_head node;
+
+	/* Trigger data */
+	char *default_trigger;
+
+	/* This protects the data in this structure */
+	rwlock_t lock;
+};
+
+void leds_set_brightness(struct led_device *led_dev, int value);
+int leds_device_register(struct device *dev, struct led_device *led_dev);
+void leds_device_unregister(struct led_device *led_dev);
+void leds_device_suspend(struct led_device *led_dev);
+void leds_device_resume(struct led_device *led_dev);
Index: linux-2.6.15-rc2/arch/arm/Kconfig
===================================================================
--- linux-2.6.15-rc2.orig/arch/arm/Kconfig	2005-11-20 03:25:03.000000000 +0000
+++ linux-2.6.15-rc2/arch/arm/Kconfig	2005-12-05 11:28:38.000000000 +0000
@@ -738,6 +738,8 @@
 
 source "drivers/mfd/Kconfig"
 
+source "drivers/leds/Kconfig"
+
 source "drivers/media/Kconfig"
 
 source "drivers/video/Kconfig"
Index: linux-2.6.15-rc2/drivers/Makefile
===================================================================
--- linux-2.6.15-rc2.orig/drivers/Makefile	2005-11-20 03:25:03.000000000 +0000
+++ linux-2.6.15-rc2/drivers/Makefile	2005-12-05 10:44:30.000000000 +0000
@@ -64,6 +64,7 @@
 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_IOC4)		+= sn/
 obj-y				+= firmware/
Index: linux-2.6.15-rc2/drivers/Kconfig
===================================================================
--- linux-2.6.15-rc2.orig/drivers/Kconfig	2005-11-20 03:25:03.000000000 +0000
+++ linux-2.6.15-rc2/drivers/Kconfig	2005-12-05 10:44:30.000000000 +0000
@@ -62,6 +62,8 @@
 
 source "drivers/mmc/Kconfig"
 
+source "drivers/leds/Kconfig"
+
 source "drivers/infiniband/Kconfig"
 
 source "drivers/sn/Kconfig"
Index: linux-2.6.15-rc2/drivers/leds/leds.h
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6.15-rc2/drivers/leds/leds.h	2005-12-05 11:29:19.000000000 +0000
@@ -0,0 +1,15 @@
+/*
+ * 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.
+ *
+ */
+
+extern rwlock_t leds_list_lock;
+extern struct list_head leds_list;
Index: linux-2.6.15-rc2/drivers/leds/led_class.c
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6.15-rc2/drivers/leds/led_class.c	2005-12-05 11:30:09.000000000 +0000
@@ -0,0 +1,171 @@
+/*
+ * LED Class Core
+ *
+ * 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.
+ */
+
+#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/leds.h>
+#include "leds.h"
+
+static void leds_class_release(struct class_device *dev)
+{
+	kfree(dev);
+}
+
+static struct class leds_class = {
+	.name		= "leds",
+	.release	= leds_class_release,
+};
+
+static ssize_t leds_show_brightness(struct class_device *dev, char *buf)
+{
+	struct led_device *led_dev = dev->class_data;
+	ssize_t ret = 0;
+
+	/* no lock needed for this */
+	sprintf(buf, "%u\n", led_dev->brightness);
+	ret = strlen(buf) + 1;
+
+	return ret;
+}
+
+static ssize_t leds_store_brightness(struct class_device *dev, const char *buf, size_t size)
+{
+	struct led_device *led_dev = dev->class_data;
+	ssize_t ret = -EINVAL;
+	char *after;
+
+	unsigned long state = simple_strtoul(buf, &after, 10);
+	if (after - buf > 0) {
+		ret = after - buf;
+		write_lock(&led_dev->lock);
+		leds_set_brightness(led_dev, state);
+		write_unlock(&led_dev->lock);
+	}
+
+	return ret;
+}
+
+static CLASS_DEVICE_ATTR(brightness, 0644, leds_show_brightness, leds_store_brightness);
+
+/* led_dev->lock must be held as write */
+void leds_set_brightness(struct led_device *led_dev, int value)
+{
+	if (value > 100)
+		value = 100;
+	led_dev->brightness = value;
+	if (!(led_dev->flags & LED_SUSPENDED))
+		led_dev->brightness_set(led_dev, value);
+}
+
+void leds_device_suspend(struct led_device *led_dev)
+{
+	write_lock(&led_dev->lock);
+	led_dev->flags |= LED_SUSPENDED;
+	led_dev->brightness_set(led_dev, 0);
+	write_unlock(&led_dev->lock);
+}
+
+void leds_device_resume(struct led_device *led_dev)
+{
+	write_lock(&led_dev->lock);
+	led_dev->flags &= ~LED_SUSPENDED;
+	led_dev->brightness_set(led_dev, led_dev->brightness);
+	write_unlock(&led_dev->lock);
+}
+
+
+/**
+ * leds_device_register - register a new object of led_device class.
+ * @dev: The device to register.
+ * @led_dev: the led_device structure for this device.
+ */
+int leds_device_register(struct device *dev, struct led_device *led_dev)
+{
+	int rc;
+
+	led_dev->class_dev = kzalloc (sizeof (struct class_device), GFP_KERNEL);
+	if (unlikely (!led_dev->class_dev))
+		return -ENOMEM;
+
+	rwlock_init(&led_dev->lock);
+
+	led_dev->class_dev->class = &leds_class;
+	led_dev->class_dev->dev = dev;
+	led_dev->class_dev->class_data = led_dev;
+
+	/* assign this led its name */
+	strncpy(led_dev->class_dev->class_id, led_dev->name, sizeof(led_dev->class_dev->class_id));
+
+	rc = class_device_register (led_dev->class_dev);
+	if (unlikely (rc)) {
+		kfree (led_dev->class_dev);
+		return rc;
+	}
+
+	/* register the attributes */
+	class_device_create_file(led_dev->class_dev, &class_device_attr_brightness);
+
+	/* add to the list of leds */
+	write_lock(&leds_list_lock);
+	list_add_tail(&led_dev->node, &leds_list);
+	write_unlock(&leds_list_lock);
+
+	printk(KERN_INFO "Registered led device: %s\n", led_dev->class_dev->class_id);
+
+	return 0;
+}
+
+/**
+ * leds_device_unregister - unregisters a object of led_properties class.
+ * @led_dev: the led device to unreigister
+ *
+ * Unregisters a previously registered via leds_device_register object.
+ */
+void leds_device_unregister(struct led_device *led_dev)
+{
+	class_device_remove_file (led_dev->class_dev, &class_device_attr_brightness);
+
+	class_device_unregister(led_dev->class_dev);
+
+	write_lock(&leds_list_lock);
+	list_del(&led_dev->node);
+	write_unlock(&leds_list_lock);
+}
+
+EXPORT_SYMBOL(leds_device_suspend);
+EXPORT_SYMBOL(leds_device_resume);
+EXPORT_SYMBOL(leds_device_register);
+EXPORT_SYMBOL(leds_device_unregister);
+
+static int __init leds_init(void)
+{
+	return class_register(&leds_class);
+}
+
+static void __exit leds_exit(void)
+{
+	class_unregister(&leds_class);
+}
+
+subsys_initcall(leds_init);
+module_exit(leds_exit);
+
+MODULE_AUTHOR("John Lenz");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("LED Class Interface");
+
Index: linux-2.6.15-rc2/drivers/leds/led_core.c
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6.15-rc2/drivers/leds/led_core.c	2005-12-05 10:44:30.000000000 +0000
@@ -0,0 +1,24 @@
+/*
+ * LED Class 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.
+ *
+ */
+
+#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);