This commit adds a new trigger that can turn on LED when USB device gets
connected to the USB port. This can can useful for various home routers
that have USB port and a proper LED telling user a device is connected.
The trigger gets its documentation file but basically it just requires
specifying USB port in a Linux format (e.g. echo 1-1 > new_port).
Signed-off-by: Rafał Miłecki <zaj...@gmail.com>
---
Documentation/leds/ledtrig-usbport.txt | 47 ++++++++
drivers/leds/trigger/Kconfig | 8 ++
drivers/leds/trigger/Makefile | 1 +
drivers/leds/trigger/ledtrig-usbport.c | 196 +++++++++++++++++++++++++++++++++
4 files changed, 252 insertions(+)
create mode 100644 Documentation/leds/ledtrig-usbport.txt
create mode 100644 drivers/leds/trigger/ledtrig-usbport.c
diff --git a/Documentation/leds/ledtrig-usbport.txt
b/Documentation/leds/ledtrig-usbport.txt
new file mode 100644
index 0000000..d31dba2
--- /dev/null
+++ b/Documentation/leds/ledtrig-usbport.txt
@@ -0,0 +1,47 @@
+USB port LED trigger
+====================
+
+This LED trigger can be used for signaling user a presence of USB device in a
+given port. It simply turns on LED when device appears and turns it off when it
+disappears.
+
+It requires specifying a list of USB ports that should be observed. Used format
+matches Linux kernel format and consists of a root hub number and a hub port
+separated by a dash (e.g. 3-1).
+
+This also allows handling devices with internal hubs (when root hub's port has
+always a device (hub) connected). User can simply specify specify internal hub
+ports then (e.g. 1-1.1, 1-1.2, etc.).
+
+Please note that this trigger allows assigning multiple USB ports to a single
+LED. This can be useful in two cases:
+
+1) Device with single USB LED and few physical ports
+
+In such case LED will be turned on as long as there is at least one connected
+USB device.
+
+2) Device with a physical port handled by few controllers
+
+Some devices have e.g. one controller per PHY standard. E.g. USB 2.0 physical
+port may be handled by ohci-platform, ehci-platform and xhci-hcd. If there is
+only one LED user will most likely want to assign ports from all 3 hubs.
+
+
+This trigger can be activated from user space on led class devices as shown
+below:
+
+ echo usbport > trigger
+
+This adds the following sysfs attributes to the LED:
+
+ ports - allows listing all USB ports assigned to the trigger.
+
+ new_port - allows adding a new USB port by simply writing to it.
+
+Example use-case:
+
+ echo usbport > trigger
+ echo 4-1 > new_port
+ echo 2-1 > new_port
+ cat ports
diff --git a/drivers/leds/trigger/Kconfig b/drivers/leds/trigger/Kconfig
index 3f9ddb9..bdd6fd2 100644
--- a/drivers/leds/trigger/Kconfig
+++ b/drivers/leds/trigger/Kconfig
@@ -126,4 +126,12 @@ config LEDS_TRIGGER_PANIC
a different trigger.
If unsure, say Y.
+config LEDS_TRIGGER_USBPORT
+ tristate "USB port LED trigger"
+ depends on LEDS_TRIGGERS && USB
+ help
+ This allows LEDs to be controlled by USB events. Enabling this option
+ allows specifying list of USB ports that should turn on LED when some
+ USB device gets connected.
+
endif # LEDS_TRIGGERS
diff --git a/drivers/leds/trigger/Makefile b/drivers/leds/trigger/Makefile
index a72c43c..56e1741 100644
--- a/drivers/leds/trigger/Makefile
+++ b/drivers/leds/trigger/Makefile
@@ -10,3 +10,4 @@ obj-$(CONFIG_LEDS_TRIGGER_DEFAULT_ON) += ledtrig-default-on.o
obj-$(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_USBPORT) += ledtrig-usbport.o
diff --git a/drivers/leds/trigger/ledtrig-usbport.c
b/drivers/leds/trigger/ledtrig-usbport.c
new file mode 100644
index 0000000..eb20a8f
--- /dev/null
+++ b/drivers/leds/trigger/ledtrig-usbport.c
@@ -0,0 +1,196 @@
+/*
+ * USB port LED trigger
+ *
+ * Copyright (C) 2016 Rafał Miłecki <rafal.mile...@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or (at
+ * your option) any later version.
+ */
+
+#include <linux/device.h>
+#include <linux/leds.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/usb.h>
+#include "../leds.h"
+
+struct usbport_trig_port {
+ char *name;
+ struct list_head list;
+};
+
+struct usbport_trig_data {
+ struct led_classdev *led_cdev;
+ struct list_head ports;
+ struct notifier_block nb;
+ int count; /* Amount of connected matching devices */
+};
+
+static ssize_t ports_show(struct device *dev, struct device_attribute *attr,
+ char *buf)
+{
+ struct led_classdev *led_cdev = dev_get_drvdata(dev);
+ struct usbport_trig_data *usbport_data = led_cdev->trigger_data;
+ struct usbport_trig_port *port;
+ ssize_t ret = 0;
+ int len;
+
+ list_for_each_entry(port, &usbport_data->ports, list) {
+ len = sprintf(buf + ret, "%s\n", port->name);
+ if (len >= 0)
+ ret += len;
+ }
+
+ return ret;
+}
+
+static DEVICE_ATTR(ports, S_IRUSR, ports_show, NULL);
+
+static ssize_t new_port_store(struct device *dev, struct device_attribute
*attr,
+ const char *buf, size_t size)
+{
+ struct led_classdev *led_cdev = dev_get_drvdata(dev);
+ struct usbport_trig_data *usbport_data = led_cdev->trigger_data;
+ struct usbport_trig_port *port;
+ size_t len;
+
+ port = kzalloc(sizeof(*port), GFP_KERNEL);
+ if (!port)
+ return -ENOMEM;
+
+ len = strlen(buf);
+ if (len && buf[len - 1] == '\n')
+ len--;
+ if (!len)
+ return -EINVAL;
+
+ port->name = kzalloc(strlen(buf), GFP_KERNEL);
+ if (!port->name) {
+ kfree(port);
+ return -ENOMEM;
+ }
+ strncpy(port->name, buf, len);
+
+ list_add_tail(&port->list, &usbport_data->ports);
+
+ return size;
+}
+
+static DEVICE_ATTR(new_port, S_IWUSR, NULL, new_port_store);
+
+static bool usbport_trig_match(struct usbport_trig_data *usbport_data,
+ struct usb_device *usb_dev)
+{
+ struct usbport_trig_port *port;
+ const char *name = dev_name(&usb_dev->dev);
+
+ list_for_each_entry(port, &usbport_data->ports, list) {
+ if (!strcmp(port->name, name))
+ return true;
+ }
+
+ return false;
+}
+
+static int usbport_trig_notify(struct notifier_block *nb, unsigned long action,
+ void *data)
+{
+ struct usbport_trig_data *usbport_data =
+ container_of(nb, struct usbport_trig_data, nb);
+ struct led_classdev *led_cdev = usbport_data->led_cdev;
+
+ switch (action) {
+ case USB_DEVICE_ADD:
+ if (usbport_trig_match(usbport_data, data)) {
+ if (usbport_data->count++ == 0)
+ led_set_brightness_nosleep(led_cdev, LED_FULL);
+ }
+ break;
+ case USB_DEVICE_REMOVE:
+ if (usbport_trig_match(usbport_data, data)) {
+ if (--usbport_data->count == 0)
+ led_set_brightness_nosleep(led_cdev, LED_OFF);
+ }
+ break;
+ }
+
+ return NOTIFY_OK;
+}
+
+static void usbport_trig_activate(struct led_classdev *led_cdev)
+{
+ struct usbport_trig_data *usbport_data;
+ int err;
+
+ usbport_data = kzalloc(sizeof(*usbport_data), GFP_KERNEL);
+ if (!usbport_data)
+ return;
+ usbport_data->led_cdev = led_cdev;
+ INIT_LIST_HEAD(&usbport_data->ports);
+ usbport_data->nb.notifier_call = usbport_trig_notify,
+ led_cdev->trigger_data = usbport_data;
+
+ err = device_create_file(led_cdev->dev, &dev_attr_ports);
+ if (err)
+ goto err_free;
+ err = device_create_file(led_cdev->dev, &dev_attr_new_port);
+ if (err)
+ goto err_remove_ports;
+
+ usb_register_notify(&usbport_data->nb);
+
+ led_cdev->activated = true;
+ return;
+
+err_free:
+ kfree(usbport_data);
+err_remove_ports:
+ device_remove_file(led_cdev->dev, &dev_attr_ports);
+}
+
+static void usbport_trig_deactivate(struct led_classdev *led_cdev)
+{
+ struct usbport_trig_data *usbport_data = led_cdev->trigger_data;
+ struct usbport_trig_port *port, *tmp;
+
+ if (!led_cdev->activated)
+ return;
+
+ usb_unregister_notify(&usbport_data->nb);
+
+ list_for_each_entry_safe(port, tmp, &usbport_data->ports, list) {
+ kfree(port->name);
+ list_del(&port->list);
+ }
+
+ device_remove_file(led_cdev->dev, &dev_attr_new_port);
+ device_remove_file(led_cdev->dev, &dev_attr_ports);
+ kfree(usbport_data);
+
+ led_cdev->activated = false;
+}
+
+static struct led_trigger usbport_led_trigger = {
+ .name = "usbport",
+ .activate = usbport_trig_activate,
+ .deactivate = usbport_trig_deactivate,
+};
+
+static int __init usbport_trig_init(void)
+{
+ return led_trigger_register(&usbport_led_trigger);
+}
+
+static void __exit usbport_trig_exit(void)
+{
+ led_trigger_unregister(&usbport_led_trigger);
+}
+
+module_init(usbport_trig_init);
+module_exit(usbport_trig_exit);
+
+MODULE_AUTHOR("Rafał Miłecki <rafal.mile...@gmail.com>");
+MODULE_DESCRIPTION("USB port trigger");
+MODULE_LICENSE("GPL");
--
1.8.4.5
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