best way to handle LEDs

[Pavel Machek]

Hi!

Handheld machines have limited number of software-controlled status
LEDs. Collie, for example has two of them; one is labeled "charge" and
second is labeled "mail".

At least the "mail" led should be handled from userspace, and it would
be nice if (at least) different speeds of blinking could be used --
original Sharp ROM uses at least:

yellow off: 	not charging
yellow on:	charging
yellow fast blink: charge error

I think even slow blinking was used somewhere. I have some code from
John Lenz (attached); it uses sysfs interface, exports led collor, and
allows setting different frequencies.

Is that acceptable, or should some other interface be used?

								Pavel


--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -244,6 +244,8 @@ source "arch/arm/mach-versatile/Kconfig"
 
 source "arch/arm/mach-aaec2000/Kconfig"
 
+source "drivers/leds/Kconfig"
+
 # Definitions to make life easier
 config ARCH_ACORN
 	bool
--- a/drivers/Kconfig
+++ b/drivers/Kconfig
@@ -54,6 +54,8 @@ source "drivers/mfd/Kconfig"
 
 source "drivers/media/Kconfig"
 
+source "drivers/leds/Kconfig"
+
 source "drivers/video/Kconfig"
 
 source "sound/Kconfig"
diff --git a/drivers/Makefile b/drivers/Makefile
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -67,3 +67,4 @@ obj-$(CONFIG_INFINIBAND)	+= infiniband/
 obj-$(CONFIG_SGI_IOC4)		+= sn/
 obj-y				+= firmware/
 obj-$(CONFIG_CRYPTO)		+= crypto/
+obj-$(CONFIG_CLASS_LEDS)	+= leds/
diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
new file mode 100644
--- /dev/null
+++ b/drivers/leds/Kconfig
@@ -0,0 +1,19 @@
+
+menu "LED devices"
+
+config CLASS_LEDS
+	tristate "LED support"
+	help
+	  This option provides the generic support for the leds class.
+	  LEDs can be accessed from /sys/class/leds.  It will also allow you
+	  to select individual drivers for LED devices.  If unsure, say N.
+
+config LEDS_LOCOMO
+	tristate "LED Support for Locomo device"
+	depends CLASS_LEDS && SHARP_LOCOMO
+	help
+	  This option enables support for the LEDs on Sharp Locomo.
+	  Zaurus models SL-5500 and SL-5600.
+
+endmenu
+
diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
new file mode 100644
--- /dev/null
+++ b/drivers/leds/Makefile
@@ -0,0 +1,4 @@
+
+# Core functionality.
+obj-$(CONFIG_CLASS_LEDS)		+= ledscore.o
+obj-$(CONFIG_LEDS_LOCOMO)		+= locomo.o
diff --git a/drivers/leds/ledscore.c b/drivers/leds/ledscore.c
new file mode 100644
--- /dev/null
+++ b/drivers/leds/ledscore.c
@@ -0,0 +1,460 @@
+/*
+ * linux/drivers/leds/ledscore.c
+ *
+ *   Copyright (C) 2005 John Lenz <lenz@xxxxxxxxxxx>
+ *
+ * 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>
+
+struct led_device {
+	/* This protects the props field.*/
+	spinlock_t lock;
+	/* If props is NULL, the driver that registered this device has been unloaded */
+	struct led_properties *props;
+
+	unsigned long frequency; /* frequency of blinking, in milliseconds */
+	int in_use; /* 1 if this device is in use by the kernel somewhere */
+	
+	struct class_device class_dev;
+	struct timer_list *ktimer;
+	struct list_head node;
+};
+
+#define to_led_device(d) container_of(d, struct led_device, class_dev)
+
+static rwlock_t leds_list_lock = RW_LOCK_UNLOCKED;
+static LIST_HEAD(leds_list);
+static rwlock_t leds_interface_list_lock = RW_LOCK_UNLOCKED;
+static LIST_HEAD(leds_interface_list);
+
+static void leds_class_release(struct class_device *dev)
+{
+	struct led_device *d = to_led_device(dev);
+
+	write_lock(&leds_list_lock);
+		list_del(&d->node);
+	write_unlock(&leds_list_lock);
+	
+	kfree(d);
+}
+
+static struct class leds_class = {
+	.name		= "leds",
+	.release	= leds_class_release,
+};
+
+static void leds_timer_function(unsigned long data)
+{
+	struct led_device *led_dev = (struct led_device *) data;
+	unsigned long delay = 0;
+	
+	spin_lock(&led_dev->lock);
+	if (led_dev->frequency) {
+		delay = led_dev->frequency;
+		if (likely(led_dev->props->brightness_get)) {
+			unsigned long value;
+			if (led_dev->props->brightness_get(led_dev->class_dev.dev, led_dev->props))
+				value = 0;
+			else
+				value = 100;
+			if (likely(led_dev->props->brightness_set))
+				led_dev->props->brightness_set(led_dev->class_dev.dev, led_dev->props, value);
+		}
+	}
+	spin_unlock(&led_dev->lock);
+
+	if (delay)
+		mod_timer(led_dev->ktimer, jiffies + msecs_to_jiffies(delay));
+}
+
+/* This function MUST be called with led_dev->lock held */
+static int leds_enable_timer(struct led_device *led_dev)
+{
+	if (led_dev->frequency && led_dev->ktimer) {
+		/* timer already created, just enable it */
+		mod_timer(led_dev->ktimer, jiffies + msecs_to_jiffies(led_dev->frequency));
+	} else if (led_dev->frequency && led_dev->ktimer == NULL) {
+		/* create a new timer */
+		led_dev->ktimer = kmalloc(sizeof(struct timer_list), GFP_KERNEL);
+		if (led_dev->ktimer) {
+			init_timer(led_dev->ktimer);
+			led_dev->ktimer->function = leds_timer_function;
+			led_dev->ktimer->data = (unsigned long) led_dev;
+			led_dev->ktimer->expires = jiffies + msecs_to_jiffies(led_dev->frequency);
+			add_timer(led_dev->ktimer);
+		} else {
+			led_dev->frequency = 0;
+			return -ENOMEM;
+		}
+	}
+
+	return 0;
+}
+
+
+static ssize_t leds_show_in_use(struct class_device *dev, char *buf)
+{
+	struct led_device *led_dev = to_led_device(dev);
+	ssize_t ret = 0;
+
+	spin_lock(&led_dev->lock);
+	sprintf(buf, "%i\n", led_dev->in_use);
+	ret = strlen(buf) + 1;
+	spin_unlock(&led_dev->lock);
+
+	return ret;
+}
+
+static CLASS_DEVICE_ATTR(in_use, 0444, leds_show_in_use, NULL);
+
+static ssize_t leds_show_color(struct class_device *dev, char *buf)
+{
+	struct led_device *led_dev = to_led_device(dev);
+	ssize_t ret = 0;
+	
+	spin_lock(&led_dev->lock);
+	if (likely(led_dev->props)) {
+		sprintf(buf, "%s\n", led_dev->props->color);
+		ret = strlen(buf) + 1;
+	}
+	spin_unlock(&led_dev->lock);
+
+	return ret;
+}
+
+static CLASS_DEVICE_ATTR(color, 0444, leds_show_color, NULL);
+
+static ssize_t leds_show_current_color(struct class_device *dev, char *buf)
+{
+	struct led_device *led_dev = to_led_device(dev);
+	ssize_t ret = 0;
+
+	spin_lock(&led_dev->lock);
+	if (likely(led_dev->props)) {
+		if (led_dev->props->color_get) {
+			sprintf(buf, "%u\n", led_dev->props->color_get(led_dev->class_dev.dev, led_dev->props));
+			ret = strlen(buf) + 1;
+		}
+	}
+	spin_unlock(&led_dev->lock);
+
+	return ret;
+}
+
+static ssize_t leds_store_current_color(struct class_device *dev, const char *buf, size_t size)
+{
+	struct led_device *led_dev = to_led_device(dev);
+	ssize_t ret = -EINVAL;
+	char *after;
+
+	unsigned long state = simple_strtoul(buf, &after, 10);
+	if (after - buf > 0) {
+		ret = after - buf;
+		spin_lock(&led_dev->lock);
+		if (led_dev->props && !led_dev->in_use) {
+			if (led_dev->props->color_set) 
+				led_dev->props->color_set(led_dev->class_dev.dev, led_dev->props, state);
+		}
+		spin_unlock(&led_dev->lock);
+	}
+
+	return ret;
+}
+
+static CLASS_DEVICE_ATTR(current_color, 0444, leds_show_current_color, leds_store_current_color);
+
+static ssize_t leds_show_brightness(struct class_device *dev, char *buf)
+{
+	struct led_device *led_dev = to_led_device(dev);
+	ssize_t ret = 0;
+
+	spin_lock(&led_dev->lock);
+	if (likely(led_dev->props)) {
+		if (likely(led_dev->props->brightness_get)) {
+			sprintf(buf, "%u\n", 
+				led_dev->props->brightness_get(led_dev->class_dev.dev, led_dev->props));
+			ret = strlen(buf) + 1;
+		}
+	}
+	spin_unlock(&led_dev->lock);
+
+	return ret;
+}
+
+static ssize_t leds_store_brightness(struct class_device *dev, const char *buf, size_t size)
+{
+	struct led_device *led_dev = to_led_device(dev);
+	ssize_t ret = -EINVAL;
+	char *after;
+
+	unsigned long state = simple_strtoul(buf, &after, 10);
+	if (after - buf > 0) {
+		ret = after - buf;
+		spin_lock(&led_dev->lock);
+		if (led_dev->props && !led_dev->in_use) {
+			if (state > 100) state = 100;
+			if (led_dev->props->brightness_set) 
+				led_dev->props->brightness_set(led_dev->class_dev.dev, led_dev->props, state);
+		}
+		spin_unlock(&led_dev->lock);
+	}
+
+	return ret;
+}
+
+static CLASS_DEVICE_ATTR(brightness, 0644, leds_show_brightness, leds_store_brightness);
+
+static ssize_t leds_show_frequency(struct class_device *dev, char *buf)
+{
+	struct led_device *led_dev = to_led_device(dev);
+	ssize_t ret = 0;
+
+	spin_lock(&led_dev->lock);
+	if (likely(led_dev->props)) {
+		sprintf(buf, "%lu\n", led_dev->frequency);
+		ret = strlen(buf) + 1;
+	}
+	spin_unlock(&led_dev->lock);
+
+	return ret;
+}
+
+static ssize_t leds_store_frequency(struct class_device *dev, const char *buf, size_t size)
+{
+	struct led_device *led_dev = to_led_device(dev);
+	int ret = -EINVAL, ret2;
+	char *after;
+
+	unsigned long state = simple_strtoul(buf, &after, 10);
+	if (after - buf > 0) {
+		ret = after - buf;
+		spin_lock(&led_dev->lock);
+		if (led_dev->props && !led_dev->in_use) {
+			led_dev->frequency = state;
+			ret2 = leds_enable_timer(led_dev);
+			if (ret2) ret = ret2;
+		}
+		spin_unlock(&led_dev->lock);
+	}
+
+	return ret;
+}
+
+static CLASS_DEVICE_ATTR(frequency, 0644, leds_show_frequency, leds_store_frequency);
+
+/**
+ * leds_device_register - register a new object of led_device class.
+ * @dev: The device to register.
+ * @prop: the led properties structure for this device.
+ */
+int leds_device_register(struct device *dev, struct led_properties *props)
+{
+	int rc;
+	struct led_device *new_led;
+	struct led_interface *interface;
+
+	new_led = kmalloc (sizeof (struct led_device), GFP_KERNEL);
+	if (unlikely (!new_led))
+		return -ENOMEM;
+
+	memset(new_led, 0, sizeof(struct led_device));
+
+	spin_lock_init(&new_led->lock);
+	new_led->props = props;
+	props->led_dev = new_led;
+
+	new_led->class_dev.class = &leds_class;
+	new_led->class_dev.dev = dev;
+
+	new_led->frequency = 0;
+	new_led->in_use = 0;
+
+	/* assign this led its name */
+	strncpy(new_led->class_dev.class_id, props->name, sizeof(new_led->class_dev.class_id));
+
+	rc = class_device_register (&new_led->class_dev);
+	if (unlikely (rc)) {
+		kfree (new_led);
+		return rc;
+	}
+
+	/* register the attributes */
+	class_device_create_file(&new_led->class_dev, &class_device_attr_in_use);
+	class_device_create_file(&new_led->class_dev, &class_device_attr_color);
+	class_device_create_file(&new_led->class_dev, &class_device_attr_current_color);
+	class_device_create_file(&new_led->class_dev, &class_device_attr_brightness);
+	class_device_create_file(&new_led->class_dev, &class_device_attr_frequency);
+
+	/* add to the list of leds */
+	write_lock(&leds_list_lock);
+		list_add_tail(&new_led->node, &leds_list);
+	write_unlock(&leds_list_lock);
+
+	/* notify any interfaces */
+	read_lock(&leds_interface_list_lock);
+	list_for_each_entry(interface, &leds_interface_list, node) {
+		if (interface->add)
+			interface->add(dev, props);
+	}
+	read_unlock(&leds_interface_list_lock);
+
+	printk(KERN_INFO "Registered led device: number=%s, color=%s\n", new_led->class_dev.class_id, props->color);
+
+	return 0;
+}
+EXPORT_SYMBOL(leds_device_register);
+
+/**
+ * leds_device_unregister - unregisters a object of led_properties class.
+ * @props: the property to unreigister
+ *
+ * Unregisters a previously registered via leds_device_register object.
+ */
+void leds_device_unregister(struct led_properties *props)
+{
+	struct led_device *led_dev;
+	struct led_interface *interface;
+
+	if (!props || !props->led_dev)
+		return;
+
+	led_dev = props->led_dev;
+
+	/* notify interfaces device is going away */
+	read_lock(&leds_interface_list_lock);
+	list_for_each_entry(interface, &leds_interface_list, node) {
+		if (interface->remove)
+			interface->remove(led_dev->class_dev.dev, props);
+	}
+	read_unlock(&leds_interface_list_lock);
+
+	class_device_remove_file (&led_dev->class_dev, &class_device_attr_frequency);
+	class_device_remove_file (&led_dev->class_dev, &class_device_attr_brightness);
+	class_device_remove_file (&led_dev->class_dev, &class_device_attr_current_color);
+	class_device_remove_file (&led_dev->class_dev, &class_device_attr_color);
+	class_device_remove_file (&led_dev->class_dev, &class_device_attr_in_use);
+
+	spin_lock(&led_dev->lock);
+	led_dev->props = NULL;
+	props->led_dev = NULL;
+	spin_unlock(&led_dev->lock);
+
+	if (led_dev->ktimer) {
+		del_timer_sync(led_dev->ktimer);
+		kfree(led_dev->ktimer);
+		led_dev->ktimer = NULL;
+	}
+
+	class_device_unregister(&led_dev->class_dev);
+}
+EXPORT_SYMBOL(leds_device_unregister);
+
+int leds_acquire(struct led_properties *led)
+{
+	int ret = -EBUSY;
+
+	spin_lock(&led->led_dev->lock);
+	if (!led->led_dev->in_use) {
+		led->led_dev->in_use = 1;
+		/* Disable the userspace blinking, if any */
+		led->led_dev->frequency = 0;
+		ret = 0;
+	}
+	spin_unlock(&led->led_dev->lock);
+
+	return ret;
+}
+EXPORT_SYMBOL(leds_acquire);
+	
+void leds_release(struct led_properties *led)
+{
+	spin_lock(&led->led_dev->lock);
+	led->led_dev->in_use = 0;
+	/* Disable the kernel blinking, if any */
+	led->led_dev->frequency = 0;
+	spin_unlock(&led->led_dev->lock);
+}
+EXPORT_SYMBOL(leds_release);
+
+/* Sets the frequency of the led in milliseconds.
+ * Only call this function after leds_acquire returns true
+ */
+int leds_set_frequency(struct led_properties *led, unsigned long frequency)
+{
+	int ret = 0;
+	
+	spin_lock(&led->led_dev->lock);
+	
+	if (!led->led_dev->in_use)
+		return -EINVAL;
+	
+	led->led_dev->frequency = frequency;
+	ret = leds_enable_timer(led->led_dev);
+
+	spin_unlock(&led->led_dev->lock);
+
+	return ret;
+}
+EXPORT_SYMBOL(leds_set_frequency);
+
+int leds_interface_register(struct led_interface *interface)
+{
+	struct led_device *led_dev;
+
+	write_lock(&leds_interface_list_lock);
+	list_add_tail(&interface->node, &leds_interface_list);
+
+	read_lock(&leds_list);
+	list_for_each_entry(led_dev, &leds_list, node) {
+		spin_lock(&led_dev->lock);
+		if (led_dev->props) {
+			interface->add(led_dev->class_dev.dev, led_dev->props);
+		}
+		spin_unlock(&led_dev->lock);
+	}
+	read_unlock(&leds_list);
+
+	write_unlock(&leds_interface_list_lock);
+
+	return 0;
+}
+EXPORT_SYMBOL(leds_interface_register);
+
+void leds_interface_unregister(struct led_interface *interface)
+{
+	write_lock(&leds_interface_list_lock);
+	list_del(&interface->node);
+	write_unlock(&leds_interface_list_lock);
+}
+EXPORT_SYMBOL(leds_interface_unregister);
+
+static int __init leds_init(void)
+{
+	/* initialize the class device */
+	return class_register(&leds_class);
+}
+subsys_initcall(leds_init);
+
+static void __exit leds_exit(void)
+{
+	class_unregister(&leds_class);
+}
+module_exit(leds_exit);
+
+MODULE_AUTHOR("John Lenz");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("LED core class interface");
+
diff --git a/drivers/leds/locomo.c b/drivers/leds/locomo.c
new file mode 100644
--- /dev/null
+++ b/drivers/leds/locomo.c
@@ -0,0 +1,124 @@
+/*
+ * linux/drivers/leds/locomo.c
+ *
+ * Copyright (C) 2005 John Lenz <lenz@xxxxxxxxxxx>
+ *
+ * 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/kernel.h>
+#include <linux/init.h>
+#include <linux/device.h>
+#include <linux/leds.h>
+
+#include <asm/hardware.h>
+#include <asm/hardware/locomo.h>
+
+struct locomoled_data {
+	unsigned long		offset;
+	int			registered;
+	int		brightness;
+	struct led_properties	props;
+};
+#define to_locomoled_data(d) container_of(d, struct locomoled_data, props)
+
+int locomoled_brightness_get(struct device *dev, struct led_properties *props)
+{
+	struct locomoled_data *data = to_locomoled_data(props);
+
+	return data->brightness;
+}
+
+void locomoled_brightness_set(struct device *dev, struct led_properties *props, int value)
+{
+	struct locomo_dev *locomo_dev = LOCOMO_DEV(dev);
+	struct locomoled_data *data = to_locomoled_data(props);
+	
+	unsigned long flags;
+
+	if (value < 0) value = 0;
+	data->brightness = value;
+	local_irq_save(flags);
+	if (data->brightness) {
+		data->brightness = 100;
+		locomo_writel(LOCOMO_LPT_TOFH, locomo_dev->mapbase + data->offset);
+	} else
+		locomo_writel(LOCOMO_LPT_TOFL, locomo_dev->mapbase + data->offset);
+	local_irq_restore(flags);
+}
+
+static struct locomoled_data leds[] = {
+	{
+		.offset	= LOCOMO_LPT0,
+		.props	= {
+			.owner		= THIS_MODULE,
+			.name		= "power",
+			.color		= "amber",
+			.brightness_get	= locomoled_brightness_get,
+			.brightness_set	= locomoled_brightness_set,
+			.color_get	= NULL,
+			.color_set	= NULL,
+		}
+	},
+	{
+		.offset	= LOCOMO_LPT1,
+		.props	= {
+			.owner		= THIS_MODULE,
+			.name		= "mail",
+			.color		= "green",
+			.brightness_get	= locomoled_brightness_get,
+			.brightness_set	= locomoled_brightness_set,
+			.color_get	= NULL,
+			.color_set	= NULL,
+		}
+	},
+};
+
+static int locomoled_probe(struct locomo_dev *dev)
+{
+	int i, ret = 0;
+	
+	for (i = 0; i < ARRAY_SIZE(leds); i++) {
+		ret = leds_device_register(&dev->dev, &leds[i].props);
+		leds[i].registered = 1;
+		if (unlikely(ret)) {
+			printk(KERN_WARNING "Unable to register locomo led %s\n", leds[i].props.color);
+			leds[i].registered = 0;
+		}
+	}
+	
+	return ret;
+}
+
+static int locomoled_remove(struct locomo_dev *dev)
+{
+	int i;
+	
+	for (i = 0; i < ARRAY_SIZE(leds); i++) {
+		if (leds[i].registered) {
+			leds_device_unregister(&leds[i].props);
+		}
+	}
+	return 0;
+}
+
+static struct locomo_driver locomoled_driver = {
+	.drv = {
+		.name = "locomoled"
+	},
+	.devid	= LOCOMO_DEVID_LED,
+	.probe	= locomoled_probe,
+	.remove	= locomoled_remove,
+};
+
+static int __init locomoled_init(void) {
+	return locomo_driver_register(&locomoled_driver);
+}
+module_init(locomoled_init);
+
+MODULE_AUTHOR("John Lenz <lenz@xxxxxxxxxxx>");
+MODULE_DESCRIPTION("Locomo LED driver");
+MODULE_LICENSE("GPL");
--- /dev/null
+++ b/include/linux/leds.h
@@ -0,0 +1,63 @@
+/*
+ *  linux/include/leds.h
+ *
+ *  Copyright (C) 2005 John Lenz <lenz@xxxxxxxxxxx>
+ *
+ * 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.
+ *
+ * Driver model for leds
+ */
+#ifndef ASM_ARM_LEDS_H
+#define ASM_ARM_LEDS_H
+
+#include <linux/device.h>
+
+struct led_device;
+
+struct led_properties {
+	struct module *owner;
+
+	/* Read-only name for this led */
+	char *name;
+	
+	/* Color of the led.  For multiple color leds, the color names should
+	 * be seperated by a "/".  For example, "amber/green".
+	 * This is read-only.
+	 */
+	char *color;
+	
+	/* For multi-colored leds, these function are called to manipulate the
+	 * current color. The integer value should be the position in the above
+	 * list of colors. For a single color led, set equal to NULL.
+	 */
+	int (*color_get)(struct device *, struct led_properties *props);
+	void (*color_set)(struct device *, struct led_properties *props, int value);
+
+	/* These functions manipulate the brightness of the led.
+	 * Values are between 0-100 */
+	int (*brightness_get)(struct device *, struct led_properties *props);
+	void (*brightness_set)(struct device *, struct led_properties *props, int value);
+	
+	/* private structure */
+	struct led_device *led_dev;
+};
+
+int leds_device_register(struct device *dev, struct led_properties *props);
+void leds_device_unregister(struct led_properties *props);
+
+int leds_acquire(struct led_properties *led);
+void leds_release(struct led_properties *led);
+int leds_set_frequency(struct led_properties *led, unsigned long frequency);
+
+struct led_interface {
+	int (*add)(struct device *dev, struct led_properties *led);
+	void (*remove)(struct device *dev, struct led_properties *led);
+
+	struct list_head node;
+};
+int leds_interface_register(struct led_interface *interface);
+void leds_interface_unregister(struct led_interface *interface);
+
+#endif

-- 
Thanks, Sharp!
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