[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>

7 files changed, 228 insertions, 0 deletions

diff --git a/drivers/Kconfig b/drivers/Kconfig
index 9f5c0da57c90..5c91d6afb117 100644
--- a/drivers/Kconfig
+++ b/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"
diff --git a/drivers/Makefile b/drivers/Makefile
index 424955274e60..d6e8ffbd8132 100644
--- a/drivers/Makefile
+++ b/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-$(CONFIG_SGI_SN)            += sn/
 obj-y                           += firmware/
diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
new file mode 100644
index 000000000000..106f9aeca04f
--- /dev/null
+++ b/drivers/leds/Kconfig
@@ -0,0 +1,18 @@
+
+menu "LED devices"
+
+config NEW_LEDS
+        bool "LED Support"
+        help
+          Say Y to enable Linux LED support.  This is not related to standard
+          keyboard LEDs which are controlled via the input system.
+
+config LEDS_CLASS
+        tristate "LED Class Support"
+        depends NEW_LEDS
+        help
+          This option enables the led sysfs class in /sys/class/leds.  You'll
+          need this to do anything useful with LEDs.  If unsure, say N.
+
+endmenu
+
diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
new file mode 100644
index 000000000000..8a62871437fa
--- /dev/null
+++ b/drivers/leds/Makefile
@@ -0,0 +1,4 @@
+
+# LED Core
+obj-$(CONFIG_NEW_LEDS)                  += led-core.o
+obj-$(CONFIG_LEDS_CLASS)                += led-class.o
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");
diff --git a/drivers/leds/led-core.c b/drivers/leds/led-core.c
new file mode 100644
index 000000000000..fe6541326c71
--- /dev/null
+++ b/drivers/leds/led-core.c
@@ -0,0 +1,25 @@
+/*
+ * 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);
diff --git a/drivers/leds/leds.h b/drivers/leds/leds.h
new file mode 100644
index 000000000000..d26ca2f7e722
--- /dev/null
+++ b/drivers/leds/leds.h
@@ -0,0 +1,31 @@
+/*
+ * 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 */