leds: trigger: Introduce a NETDEV trigger

This commit introduces a NETDEV trigger for named device
activity. Available triggers are link, rx, and tx.

Signed-off-by: Ben Whitten <[e-mail]>
Acked-by: Pavel Machek <[e-mail]>
Signed-off-by: Jacek Anaszewski <[e-mail]>

Documentation/ABI/testing/sysfs-class-led-trigger-netdev

···
+What:		/sys/class/leds/<led>/device_name
+Date:		Dec 2017
+KernelVersion:	4.16
+Contact:	[e-mail]
+Description:
+		Specifies the network device name to monitor.
+
+What:		/sys/class/leds/<led>/interval
+Date:		Dec 2017
+KernelVersion:	4.16
+Contact:	[e-mail]
+Description:
+		Specifies the duration of the LED blink in milliseconds.
+		Defaults to 50 ms.
+
+What:		/sys/class/leds/<led>/link
+Date:		Dec 2017
+KernelVersion:	4.16
+Contact:	[e-mail]
+Description:
+		Signal the link state of the named network device.
+		If set to 0 (default), the LED's normal state is off.
+		If set to 1, the LED's normal state reflects the link state
+		of the named network device.
+		Setting this value also immediately changes the LED state.
+
+What:		/sys/class/leds/<led>/tx
+Date:		Dec 2017
+KernelVersion:	4.16
+Contact:	[e-mail]
+Description:
+		Signal transmission of data on the named network device.
+		If set to 0 (default), the LED will not blink on transmission.
+		If set to 1, the LED will blink for the milliseconds specified
+		in interval to signal transmission.
+
+What:		/sys/class/leds/<led>/rx
+Date:		Dec 2017
+KernelVersion:	4.16
+Contact:	[e-mail]
+Description:
+		Signal reception of data on the named network device.
+		If set to 0 (default), the LED will not blink on reception.
+		If set to 1, the LED will blink for the milliseconds specified
+		in interval to signal reception.

drivers/leds/trigger/Kconfig

···
 	  a different trigger.
 	  If unsure, say Y.
 
+config LEDS_TRIGGER_NETDEV
+	tristate "LED Netdev Trigger"
+	depends on NET && LEDS_TRIGGERS
+	help
+	  This allows LEDs to be controlled by network device activity.
+	  If unsure, say Y.
+
 endif # LEDS_TRIGGERS

drivers/leds/trigger/Makefile

···
 obj-$(CONFIG_LEDS_TRIGGER_TRANSIENT)	+= ledtrig-transient.o
 obj-$(CONFIG_LEDS_TRIGGER_CAMERA)	+= ledtrig-camera.o
 obj-$(CONFIG_LEDS_TRIGGER_PANIC)	+= ledtrig-panic.o
+obj-$(CONFIG_LEDS_TRIGGER_NETDEV)	+= ledtrig-netdev.o

drivers/leds/trigger/ledtrig-netdev.c

···
+// SPDX-License-Identifier: GPL-2.0
+// Copyright 2017 Ben Whitten <[e-mail]>
+// Copyright 2007 Oliver Jowett <[e-mail]>
+//
+// LED Kernel Netdev Trigger
+//
+// Toggles the LED to reflect the link and traffic state of a named net device
+//
+// Derived from ledtrig-timer.c which is:
+//  Copyright 2005-2006 Openedhand Ltd.
+//  Author: Richard Purdie <[e-mail]>
+
+#include <linux/atomic.h>
+#include <linux/ctype.h>
+#include <linux/device.h>
+#include <linux/init.h>
+#include <linux/jiffies.h>
+#include <linux/kernel.h>
+#include <linux/leds.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/netdevice.h>
+#include <linux/spinlock.h>
+#include <linux/timer.h>
+#include "../leds.h"
+
+/*
+ * Configurable sysfs attributes:
+ *
+ * device_name - network device name to monitor
+ * interval - duration of LED blink, in milliseconds
+ * link -  LED's normal state reflects whether the link is up
+ *         (has carrier) or not
+ * tx -  LED blinks on transmitted data
+ * rx -  LED blinks on receive data
+ *
+ */
+
+struct led_netdev_data {
+	spinlock_t lock;
+
+	struct delayed_work work;
+	struct notifier_block notifier;
+
+	struct led_classdev *led_cdev;
+	struct net_device *net_dev;
+
+	char device_name[IFNAMSIZ];
+	atomic_t interval;
+	unsigned int last_activity;
+
+	unsigned long mode;
+#define NETDEV_LED_LINK	0
+#define NETDEV_LED_TX	1
+#define NETDEV_LED_RX	2
+#define NETDEV_LED_MODE_LINKUP	3
+};
+
+enum netdev_led_attr {
+	NETDEV_ATTR_LINK,
+	NETDEV_ATTR_TX,
+	NETDEV_ATTR_RX
+};
+
+static void set_baseline_state(struct led_netdev_data *trigger_data)
+{
+	int current_brightness;
+	struct led_classdev *led_cdev = trigger_data->led_cdev;
+
+	current_brightness = led_cdev->brightness;
+	if (current_brightness)
+		led_cdev->blink_brightness = current_brightness;
+	if (!led_cdev->blink_brightness)
+		led_cdev->blink_brightness = led_cdev->max_brightness;
+
+	if (!test_bit(NETDEV_LED_MODE_LINKUP, &trigger_data->mode))
+		led_set_brightness(led_cdev, LED_OFF);
+	else {
+		if (test_bit(NETDEV_LED_LINK, &trigger_data->mode))
+			led_set_brightness(led_cdev,
+					   led_cdev->blink_brightness);
+		else
+			led_set_brightness(led_cdev, LED_OFF);
+
+		/* If we are looking for RX/TX start periodically
+		 * checking stats
+		 */
+		if (test_bit(NETDEV_LED_TX, &trigger_data->mode) ||
+		    test_bit(NETDEV_LED_RX, &trigger_data->mode))
+			schedule_delayed_work(&trigger_data->work, 0);
+	}
+}
+
+static ssize_t device_name_show(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct led_classdev *led_cdev = dev_get_drvdata(dev);
+	struct led_netdev_data *trigger_data = led_cdev->trigger_data;
+	ssize_t len;
+
+	spin_lock_bh(&trigger_data->lock);
+	len = sprintf(buf, "%s\n", trigger_data->device_name);
+	spin_unlock_bh(&trigger_data->lock);
+
+	return len;
+}
+
+static ssize_t device_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 led_netdev_data *trigger_data = led_cdev->trigger_data;
+
+	if (size >= IFNAMSIZ)
+		return -EINVAL;
+
+	cancel_delayed_work_sync(&trigger_data->work);
+
+	spin_lock_bh(&trigger_data->lock);
+
+	if (trigger_data->net_dev) {
+		dev_put(trigger_data->net_dev);
+		trigger_data->net_dev = NULL;
+	}
+
+	strncpy(trigger_data->device_name, buf, size);
+	if (size > 0 && trigger_data->device_name[size - 1] == '\n')
+		trigger_data->device_name[size - 1] = 0;
+
+	if (trigger_data->device_name[0] != 0)
+		trigger_data->net_dev =
+		    dev_get_by_name(&init_net, trigger_data->device_name);
+
+	clear_bit(NETDEV_LED_MODE_LINKUP, &trigger_data->mode);
+	if (trigger_data->net_dev != NULL)
+		if (netif_carrier_ok(trigger_data->net_dev))
+			set_bit(NETDEV_LED_MODE_LINKUP, &trigger_data->mode);
+
+	trigger_data->last_activity = 0;
+
+	set_baseline_state(trigger_data);
+	spin_unlock_bh(&trigger_data->lock);
+
+	return size;
+}
+
+static DEVICE_ATTR_RW(device_name);
+
+static ssize_t netdev_led_attr_show(struct device *dev, char *buf,
+	enum netdev_led_attr attr)
+{
+	struct led_classdev *led_cdev = dev_get_drvdata(dev);
+	struct led_netdev_data *trigger_data = led_cdev->trigger_data;
+	int bit;
+
+	switch (attr) {
+	case NETDEV_ATTR_LINK:
+		bit = NETDEV_LED_LINK;
+		break;
+	case NETDEV_ATTR_TX:
+		bit = NETDEV_LED_TX;
+		break;
+	case NETDEV_ATTR_RX:
+		bit = NETDEV_LED_RX;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return sprintf(buf, "%u\n", test_bit(bit, &trigger_data->mode));
+}
+
+static ssize_t netdev_led_attr_store(struct device *dev, const char *buf,
+	size_t size, enum netdev_led_attr attr)
+{
+	struct led_classdev *led_cdev = dev_get_drvdata(dev);
+	struct led_netdev_data *trigger_data = led_cdev->trigger_data;
+	unsigned long state;
+	int ret;
+	int bit;
+
+	ret = kstrtoul(buf, 0, &state);
+	if (ret)
+		return ret;
+
+	switch (attr) {
+	case NETDEV_ATTR_LINK:
+		bit = NETDEV_LED_LINK;
+		break;
+	case NETDEV_ATTR_TX:
+		bit = NETDEV_LED_TX;
+		break;
+	case NETDEV_ATTR_RX:
+		bit = NETDEV_LED_RX;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	cancel_delayed_work_sync(&trigger_data->work);
+
+	if (state)
+		set_bit(bit, &trigger_data->mode);
+	else
+		clear_bit(bit, &trigger_data->mode);
+
+	set_baseline_state(trigger_data);
+
+	return size;
+}
+
+static ssize_t link_show(struct device *dev,
+	struct device_attribute *attr, char *buf)
+{
+	return netdev_led_attr_show(dev, buf, NETDEV_ATTR_LINK);
+}
+
+static ssize_t link_store(struct device *dev,
+	struct device_attribute *attr, const char *buf, size_t size)
+{
+	return netdev_led_attr_store(dev, buf, size, NETDEV_ATTR_LINK);
+}
+
+static DEVICE_ATTR_RW(link);
+
+static ssize_t tx_show(struct device *dev,
+	struct device_attribute *attr, char *buf)
+{
+	return netdev_led_attr_show(dev, buf, NETDEV_ATTR_TX);
+}
+
+static ssize_t tx_store(struct device *dev,
+	struct device_attribute *attr, const char *buf, size_t size)
+{
+	return netdev_led_attr_store(dev, buf, size, NETDEV_ATTR_TX);
+}
+
+static DEVICE_ATTR_RW(tx);
+
+static ssize_t rx_show(struct device *dev,
+	struct device_attribute *attr, char *buf)
+{
+	return netdev_led_attr_show(dev, buf, NETDEV_ATTR_RX);
+}
+
+static ssize_t rx_store(struct device *dev,
+	struct device_attribute *attr, const char *buf, size_t size)
+{
+	return netdev_led_attr_store(dev, buf, size, NETDEV_ATTR_RX);
+}
+
+static DEVICE_ATTR_RW(rx);
+
+static ssize_t interval_show(struct device *dev,
+			     struct device_attribute *attr, char *buf)
+{
+	struct led_classdev *led_cdev = dev_get_drvdata(dev);
+	struct led_netdev_data *trigger_data = led_cdev->trigger_data;
+
+	return sprintf(buf, "%u\n",
+		       jiffies_to_msecs(atomic_read(&trigger_data->interval)));
+}
+
+static ssize_t 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 led_netdev_data *trigger_data = led_cdev->trigger_data;
+	unsigned long value;
+	int ret;
+
+	ret = kstrtoul(buf, 0, &value);
+	if (ret)
+		return ret;
+
+	/* impose some basic bounds on the timer interval */
+	if (value >= 5 && value <= 10000) {
+		cancel_delayed_work_sync(&trigger_data->work);
+
+		atomic_set(&trigger_data->interval, msecs_to_jiffies(value));
+		set_baseline_state(trigger_data);	/* resets timer */
+	}
+
+	return size;
+}
+
+static DEVICE_ATTR_RW(interval);
+
+static int netdev_trig_notify(struct notifier_block *nb,
+			      unsigned long evt, void *dv)
+{
+	struct net_device *dev =
+		netdev_notifier_info_to_dev((struct netdev_notifier_info *)dv);
+	struct led_netdev_data *trigger_data = container_of(nb,
+							    struct
+							    led_netdev_data,
+							    notifier);
+
+	if (evt != NETDEV_UP && evt != NETDEV_DOWN && evt != NETDEV_CHANGE
+	    && evt != NETDEV_REGISTER && evt != NETDEV_UNREGISTER
+	    && evt != NETDEV_CHANGENAME)
+		return NOTIFY_DONE;
+
+	if (strcmp(dev->name, trigger_data->device_name))
+		return NOTIFY_DONE;
+
+	cancel_delayed_work_sync(&trigger_data->work);
+
+	spin_lock_bh(&trigger_data->lock);
+
+	clear_bit(NETDEV_LED_MODE_LINKUP, &trigger_data->mode);
+	switch (evt) {
+	case NETDEV_REGISTER:
+		if (trigger_data->net_dev)
+			dev_put(trigger_data->net_dev);
+		dev_hold(dev);
+		trigger_data->net_dev = dev;
+		break;
+	case NETDEV_CHANGENAME:
+	case NETDEV_UNREGISTER:
+		if (trigger_data->net_dev) {
+			dev_put(trigger_data->net_dev);
+			trigger_data->net_dev = NULL;
+		}
+		break;
+	case NETDEV_UP:
+	case NETDEV_CHANGE:
+		if (netif_carrier_ok(dev))
+			set_bit(NETDEV_LED_MODE_LINKUP, &trigger_data->mode);
+		break;
+	}
+
+	set_baseline_state(trigger_data);
+
+	spin_unlock_bh(&trigger_data->lock);
+
+	return NOTIFY_DONE;
+}
+
+/* here's the real work! */
+static void netdev_trig_work(struct work_struct *work)
+{
+	struct led_netdev_data *trigger_data = container_of(work,
+							    struct
+							    led_netdev_data,
+							    work.work);
+	struct rtnl_link_stats64 *dev_stats;
+	unsigned int new_activity;
+	struct rtnl_link_stats64 temp;
+	unsigned long interval;
+	int invert;
+
+	/* If we dont have a device, insure we are off */
+	if (!trigger_data->net_dev) {
+		led_set_brightness(trigger_data->led_cdev, LED_OFF);
+		return;
+	}
+
+	/* If we are not looking for RX/TX then return  */
+	if (!test_bit(NETDEV_LED_TX, &trigger_data->mode) &&
+	    !test_bit(NETDEV_LED_RX, &trigger_data->mode))
+		return;
+
+	dev_stats = dev_get_stats(trigger_data->net_dev, &temp);
+	new_activity =
+	    (test_bit(NETDEV_LED_TX, &trigger_data->mode) ?
+		dev_stats->tx_packets : 0) +
+	    (test_bit(NETDEV_LED_RX, &trigger_data->mode) ?
+		dev_stats->rx_packets : 0);
+
+	if (trigger_data->last_activity != new_activity) {
+		led_stop_software_blink(trigger_data->led_cdev);
+
+		invert = test_bit(NETDEV_LED_LINK, &trigger_data->mode);
+		interval = jiffies_to_msecs(
+				atomic_read(&trigger_data->interval));
+		/* base state is ON (link present) */
+		led_blink_set_oneshot(trigger_data->led_cdev,
+				      &interval,
+				      &interval,
+				      invert);
+		trigger_data->last_activity = new_activity;
+	}
+
+	schedule_delayed_work(&trigger_data->work,
+			(atomic_read(&trigger_data->interval)*2));
+}
+
+static void netdev_trig_activate(struct led_classdev *led_cdev)
+{
+	struct led_netdev_data *trigger_data;
+	int rc;
+
+	trigger_data = kzalloc(sizeof(struct led_netdev_data), GFP_KERNEL);
+	if (!trigger_data)
+		return;
+
+	spin_lock_init(&trigger_data->lock);
+
+	trigger_data->notifier.notifier_call = netdev_trig_notify;
+	trigger_data->notifier.priority = 10;
+
+	INIT_DELAYED_WORK(&trigger_data->work, netdev_trig_work);
+
+	trigger_data->led_cdev = led_cdev;
+	trigger_data->net_dev = NULL;
+	trigger_data->device_name[0] = 0;
+
+	trigger_data->mode = 0;
+	atomic_set(&trigger_data->interval, msecs_to_jiffies(50));
+	trigger_data->last_activity = 0;
+
+	led_cdev->trigger_data = trigger_data;
+
+	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_link);
+	if (rc)
+		goto err_out_device_name;
+	rc = device_create_file(led_cdev->dev, &dev_attr_rx);
+	if (rc)
+		goto err_out_link;
+	rc = device_create_file(led_cdev->dev, &dev_attr_tx);
+	if (rc)
+		goto err_out_rx;
+	rc = device_create_file(led_cdev->dev, &dev_attr_interval);
+	if (rc)
+		goto err_out_tx;
+	rc = register_netdevice_notifier(&trigger_data->notifier);
+	if (rc)
+		goto err_out_interval;
+	return;
+
+err_out_interval:
+	device_remove_file(led_cdev->dev, &dev_attr_interval);
+err_out_tx:
+	device_remove_file(led_cdev->dev, &dev_attr_tx);
+err_out_rx:
+	device_remove_file(led_cdev->dev, &dev_attr_rx);
+err_out_link:
+	device_remove_file(led_cdev->dev, &dev_attr_link);
+err_out_device_name:
+	device_remove_file(led_cdev->dev, &dev_attr_device_name);
+err_out:
+	led_cdev->trigger_data = NULL;
+	kfree(trigger_data);
+}
+
+static void netdev_trig_deactivate(struct led_classdev *led_cdev)
+{
+	struct led_netdev_data *trigger_data = led_cdev->trigger_data;
+
+	if (trigger_data) {
+		unregister_netdevice_notifier(&trigger_data->notifier);
+
+		device_remove_file(led_cdev->dev, &dev_attr_device_name);
+		device_remove_file(led_cdev->dev, &dev_attr_link);
+		device_remove_file(led_cdev->dev, &dev_attr_rx);
+		device_remove_file(led_cdev->dev, &dev_attr_tx);
+		device_remove_file(led_cdev->dev, &dev_attr_interval);
+
+		cancel_delayed_work_sync(&trigger_data->work);
+
+		if (trigger_data->net_dev)
+			dev_put(trigger_data->net_dev);
+
+		kfree(trigger_data);
+	}
+}
+
+static struct led_trigger netdev_led_trigger = {
+	.name = "netdev",
+	.activate = netdev_trig_activate,
+	.deactivate = netdev_trig_deactivate,
+};
+
+static int __init netdev_trig_init(void)
+{
+	return led_trigger_register(&netdev_led_trigger);
+}
+
+static void __exit netdev_trig_exit(void)
+{
+	led_trigger_unregister(&netdev_led_trigger);
+}
+
+module_init(netdev_trig_init);
+module_exit(netdev_trig_exit);
+
+MODULE_AUTHOR("Ben Whitten <[e-mail]>");
+MODULE_AUTHOR("Oliver Jowett <[e-mail]>");
+MODULE_DESCRIPTION("Netdev LED trigger");
+MODULE_LICENSE("GPL v2");