generic: add LED trigger for USB device presence/activity

SVN-Revision: 24646

1 files changed, 348 insertions, 0 deletions

diff --git a/target/linux/generic/files/drivers/leds/ledtrig-usbdev.c b/target/linux/generic/files/drivers/leds/ledtrig-usbdev.c
new file mode 100644
index 0000000..70b0e39
--- /dev/null
+++ b/target/linux/generic/files/drivers/leds/ledtrig-usbdev.c
@@ -0,0 +1,348 @@
+/*
+ * LED USB device Trigger
+ *
+ * Toggles the LED to reflect the presence and activity of an USB device
+ * Copyright (C) Gabor Juhos <juhosg@openwrt.org>
+ *
+ * derived from ledtrig-netdev.c:
+ *	Copyright 2007 Oliver Jowett <oliver@opencloud.com>
+ *
+ * ledtrig-netdev.c derived from ledtrig-timer.c:
+ *	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/module.h>
+#include <linux/jiffies.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/ctype.h>
+#include <linux/slab.h>
+#include <linux/leds.h>
+#include <linux/usb.h>
+
+#include "leds.h"
+
+#define DEV_BUS_ID_SIZE		32
+
+/*
+ * Configurable sysfs attributes:
+ *
+ * device_name - name of the USB device to monitor
+ * activity_interval - duration of LED blink, in milliseconds
+ */
+
+struct usbdev_trig_data {
+	rwlock_t lock;
+
+	struct timer_list timer;
+	struct notifier_block notifier;
+
+	struct led_classdev *led_cdev;
+	struct usb_device *usb_dev;
+
+	char device_name[DEV_BUS_ID_SIZE];
+	unsigned interval;
+	int last_urbnum;
+};
+
+static void usbdev_trig_update_state(struct usbdev_trig_data *td)
+{
+	if (td->usb_dev)
+		led_set_brightness(td->led_cdev, LED_FULL);
+	else
+		led_set_brightness(td->led_cdev, LED_OFF);
+
+	if (td->interval && td->usb_dev)
+		mod_timer(&td->timer, jiffies + td->interval);
+	else
+		del_timer(&td->timer);
+}
+
+static ssize_t usbdev_trig_name_show(struct device *dev,
+				     struct device_attribute *attr,
+				     char *buf)
+{
+	struct led_classdev *led_cdev = dev_get_drvdata(dev);
+	struct usbdev_trig_data *td = led_cdev->trigger_data;
+
+	read_lock(&td->lock);
+	sprintf(buf, "%s\n", td->device_name);
+	read_unlock(&td->lock);
+
+	return strlen(buf) + 1;
+}
+
+static ssize_t usbdev_trig_name_store(struct device *dev,
+				      struct device_attribute *attr,
+				      const char *buf,
+				      size_t size)
+{
+	struct led_classdev *led_cdev = dev_get_drvdata(dev);
+	struct usbdev_trig_data *td = led_cdev->trigger_data;
+
+	if (size < 0 || size >= DEV_BUS_ID_SIZE)
+		return -EINVAL;
+
+	write_lock(&td->lock);
+
+	strcpy(td->device_name, buf);
+	if (size > 0 && td->device_name[size - 1] == '\n')
+		td->device_name[size - 1] = 0;
+
+	if (td->device_name[0] != 0) {
+		struct usb_device *usb_dev;
+
+		/* check for existing device to update from */
+		usb_dev = usb_find_device_by_name(td->device_name);
+		if (usb_dev) {
+			if (td->usb_dev)
+				usb_put_dev(td->usb_dev);
+
+			td->usb_dev = usb_dev;
+			td->last_urbnum = atomic_read(&usb_dev->urbnum);
+		}
+
+		/* updates LEDs, may start timers */
+		usbdev_trig_update_state(td);
+	}
+
+	write_unlock(&td->lock);
+	return size;
+}
+
+static DEVICE_ATTR(device_name, 0644, usbdev_trig_name_show,
+		   usbdev_trig_name_store);
+
+static ssize_t usbdev_trig_interval_show(struct device *dev,
+				 	 struct device_attribute *attr,
+					 char *buf)
+{
+	struct led_classdev *led_cdev = dev_get_drvdata(dev);
+	struct usbdev_trig_data *td = led_cdev->trigger_data;
+
+	read_lock(&td->lock);
+	sprintf(buf, "%u\n", jiffies_to_msecs(td->interval));
+	read_unlock(&td->lock);
+
+	return strlen(buf) + 1;
+}
+
+static ssize_t usbdev_trig_interval_store(struct device *dev,
+					  struct device_attribute *attr,
+					  const char *buf,
+					  size_t size)
+{
+	struct led_classdev *led_cdev = dev_get_drvdata(dev);
+	struct usbdev_trig_data *td = led_cdev->trigger_data;
+	int ret = -EINVAL;
+	char *after;
+	unsigned long value = simple_strtoul(buf, &after, 10);
+	size_t count = after - buf;
+
+	if (*after && isspace(*after))
+		count++;
+
+	if (count == size && value <= 10000) {
+		write_lock(&td->lock);
+		td->interval = msecs_to_jiffies(value);
+		usbdev_trig_update_state(td); /* resets timer */
+		write_unlock(&td->lock);
+		ret = count;
+	}
+
+	return ret;
+}
+
+static DEVICE_ATTR(activity_interval, 0644, usbdev_trig_interval_show,
+		   usbdev_trig_interval_store);
+
+static int usbdev_trig_notify(struct notifier_block *nb,
+			      unsigned long evt,
+			      void *data)
+{
+	struct usb_device *usb_dev;
+	struct usbdev_trig_data *td;
+
+	if (evt != USB_DEVICE_ADD && evt != USB_DEVICE_REMOVE)
+		return NOTIFY_DONE;
+
+	usb_dev = data;
+	td = container_of(nb, struct usbdev_trig_data, notifier);
+
+	write_lock(&td->lock);
+
+	if (strcmp(dev_name(&usb_dev->dev), td->device_name))
+		goto done;
+
+	if (evt == USB_DEVICE_ADD) {
+		usb_get_dev(usb_dev);
+		if (td->usb_dev != NULL)
+			usb_put_dev(td->usb_dev);
+		td->usb_dev = usb_dev;
+		td->last_urbnum = atomic_read(&usb_dev->urbnum);
+	} else if (evt == USB_DEVICE_REMOVE) {
+		if (td->usb_dev != NULL) {
+			usb_put_dev(td->usb_dev);
+			td->usb_dev = NULL;
+		}
+	}
+
+	usbdev_trig_update_state(td);
+
+done:
+	write_unlock(&td->lock);
+	return NOTIFY_DONE;
+}
+
+/* here's the real work! */
+static void usbdev_trig_timer(unsigned long arg)
+{
+	struct usbdev_trig_data *td = (struct usbdev_trig_data *)arg;
+	int new_urbnum;
+
+	write_lock(&td->lock);
+
+	if (!td->usb_dev || td->interval == 0) {
+		/*
+		 * we don't need to do timer work, just reflect device presence
+		 */
+		if (td->usb_dev)
+			led_set_brightness(td->led_cdev, LED_FULL);
+		else
+			led_set_brightness(td->led_cdev, LED_OFF);
+
+		goto no_restart;
+	}
+
+	if (td->interval)
+		new_urbnum = atomic_read(&td->usb_dev->urbnum);
+	else
+		new_urbnum = 0;
+
+	if (td->usb_dev) {
+		/*
+		 * Base state is ON (device is present). If there's no device,
+		 * we don't get this far and the LED is off.
+		 * OFF -> ON always
+		 * ON -> OFF on activity
+		 */
+		if (td->led_cdev->brightness == LED_OFF)
+			led_set_brightness(td->led_cdev, LED_FULL);
+		else if (td->last_urbnum != new_urbnum)
+			led_set_brightness(td->led_cdev, LED_OFF);
+	} else {
+		/*
+		 * base state is OFF
+		 * ON -> OFF always
+		 * OFF -> ON on activity
+		 */
+		if (td->led_cdev->brightness == LED_FULL)
+			led_set_brightness(td->led_cdev, LED_OFF);
+		else if (td->last_urbnum != new_urbnum)
+			led_set_brightness(td->led_cdev, LED_FULL);
+	}
+
+	td->last_urbnum = new_urbnum;
+	mod_timer(&td->timer, jiffies + td->interval);
+
+no_restart:
+	write_unlock(&td->lock);
+}
+
+static void usbdev_trig_activate(struct led_classdev *led_cdev)
+{
+	struct usbdev_trig_data *td;
+	int rc;
+
+	td = kzalloc(sizeof(struct usbdev_trig_data), GFP_KERNEL);
+	if (!td)
+		return;
+
+	rwlock_init(&td->lock);
+
+	td->notifier.notifier_call = usbdev_trig_notify;
+	td->notifier.priority = 10;
+
+	setup_timer(&td->timer, usbdev_trig_timer, (unsigned long) td);
+
+	td->led_cdev = led_cdev;
+	td->interval = msecs_to_jiffies(50);
+
+	led_cdev->trigger_data = td;
+
+	rc = device_create_file(led_cdev->dev, &dev_attr_device_name);
+	if (rc)
+		goto err_out;
+
+	rc = device_create_file(led_cdev->dev, &dev_attr_activity_interval);
+	if (rc)
+		goto err_out_device_name;
+
+	usb_register_notify(&td->notifier);
+	return;
+
+err_out_device_name:
+	device_remove_file(led_cdev->dev, &dev_attr_device_name);
+err_out:
+	led_cdev->trigger_data = NULL;
+	kfree(td);
+}
+
+static void usbdev_trig_deactivate(struct led_classdev *led_cdev)
+{
+	struct usbdev_trig_data *td = led_cdev->trigger_data;
+
+	if (td) {
+		usb_unregister_notify(&td->notifier);
+
+		device_remove_file(led_cdev->dev, &dev_attr_device_name);
+		device_remove_file(led_cdev->dev, &dev_attr_activity_interval);
+
+		write_lock(&td->lock);
+
+		if (td->usb_dev) {
+			usb_put_dev(td->usb_dev);
+			td->usb_dev = NULL;
+		}
+
+		write_unlock(&td->lock);
+
+		del_timer_sync(&td->timer);
+
+		kfree(td);
+	}
+}
+
+static struct led_trigger usbdev_led_trigger = {
+	.name		= "usbdev",
+	.activate	= usbdev_trig_activate,
+	.deactivate	= usbdev_trig_deactivate,
+};
+
+static int __init usbdev_trig_init(void)
+{
+	return led_trigger_register(&usbdev_led_trigger);
+}
+
+static void __exit usbdev_trig_exit(void)
+{
+	led_trigger_unregister(&usbdev_led_trigger);
+}
+
+module_init(usbdev_trig_init);
+module_exit(usbdev_trig_exit);
+
+MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
+MODULE_DESCRIPTION("USB device LED trigger");
+MODULE_LICENSE("GPL v2");