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authorRafał Miłecki <rafal@milecki.pl>2016-10-04 11:22:49 +0200
committerRafał Miłecki <rafal@milecki.pl>2016-10-04 12:08:25 +0200
commita69e19d18ac0ebb3a715def18fed37026cae15af (patch)
treeac2d3f6509ab44b8fb3b37b1199fcab35252db47
parentdf5416296cda4f7338a3d6eea361f8e8c8d667c6 (diff)
downloadupstream-a69e19d18ac0ebb3a715def18fed37026cae15af.tar.gz
upstream-a69e19d18ac0ebb3a715def18fed37026cae15af.tar.bz2
upstream-a69e19d18ac0ebb3a715def18fed37026cae15af.zip
kernel: backport usbport LED trigger from 4.9
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
-rw-r--r--target/linux/generic/config-4.11
-rw-r--r--target/linux/generic/config-4.41
-rw-r--r--target/linux/generic/patches-4.1/082-usb-core-Introduce-a-USB-port-LED-trigger.patch464
-rw-r--r--target/linux/generic/patches-4.4/084-usb-core-Introduce-a-USB-port-LED-trigger.patch465
4 files changed, 931 insertions, 0 deletions
diff --git a/target/linux/generic/config-4.1 b/target/linux/generic/config-4.1
index 0b5eccb7ea..216eba4672 100644
--- a/target/linux/generic/config-4.1
+++ b/target/linux/generic/config-4.1
@@ -4425,6 +4425,7 @@ CONFIG_USB_OHCI_LITTLE_ENDIAN=y
# CONFIG_USB_OTG_BLACKLIST_HUB is not set
# CONFIG_USB_OTG_FSM is not set
# CONFIG_USB_OTG_WHITELIST is not set
+# CONFIG_USB_LEDS_TRIGGER_USBPORT is not set
# CONFIG_USB_OXU210HP_HCD is not set
# CONFIG_USB_PEGASUS is not set
# CONFIG_USB_PHY is not set
diff --git a/target/linux/generic/config-4.4 b/target/linux/generic/config-4.4
index c2d521f8c8..7a0efa365a 100644
--- a/target/linux/generic/config-4.4
+++ b/target/linux/generic/config-4.4
@@ -4453,6 +4453,7 @@ CONFIG_USB_OHCI_LITTLE_ENDIAN=y
# CONFIG_USB_OTG_BLACKLIST_HUB is not set
# CONFIG_USB_OTG_FSM is not set
# CONFIG_USB_OTG_WHITELIST is not set
+# CONFIG_USB_LEDS_TRIGGER_USBPORT is not set
# CONFIG_USB_OXU210HP_HCD is not set
# CONFIG_USB_PEGASUS is not set
# CONFIG_USB_PHY is not set
diff --git a/target/linux/generic/patches-4.1/082-usb-core-Introduce-a-USB-port-LED-trigger.patch b/target/linux/generic/patches-4.1/082-usb-core-Introduce-a-USB-port-LED-trigger.patch
new file mode 100644
index 0000000000..ade7f9c8bb
--- /dev/null
+++ b/target/linux/generic/patches-4.1/082-usb-core-Introduce-a-USB-port-LED-trigger.patch
@@ -0,0 +1,464 @@
+From 0f247626cbbfa2010d2b86fdee652605e084e248 Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <rafal@milecki.pl>
+Date: Fri, 16 Sep 2016 16:13:48 +0200
+Subject: [PATCH] usb: core: Introduce a USB port LED trigger
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+This commit adds a new trigger responsible for turning on LED when USB
+device gets connected to the selected USB port. This can can useful for
+various home routers that have USB port(s) and a proper LED telling user
+a device is connected.
+
+The trigger gets its documentation file but basically it just requires
+enabling it and selecting USB ports (e.g. echo 1 > ports/usb1-1).
+
+There was a long discussion on design of this driver. Its current state
+is a result of picking them most adjustable solution as others couldn't
+handle all cases.
+
+1) It wasn't possible for the driver to register separated trigger for
+ each USB port. Some physical USB ports are handled by more than one
+ controller and so by more than one USB port. E.g. USB 2.0 physical
+ port may be handled by OHCI's port and EHCI's port.
+ It's also not possible to assign more than 1 trigger to a single LED
+ and implementing such feature would be tricky due to syncing triggers
+ and sysfs conflicts with old triggers.
+
+2) Another idea was to register trigger per USB hub. This wouldn't allow
+ handling devices with multiple USB LEDs and controllers (hubs)
+ controlling more than 1 physical port. It's common for hubs to have
+ few ports and each may have its own LED.
+
+This final trigger is highly flexible. It allows selecting any USB ports
+for any LED. It was also modified (comparing to the initial version) to
+allow choosing ports rather than having user /guess/ proper names. It
+was successfully tested on SmartRG SR400ac which has 3 USB LEDs,
+2 physical ports and 3 controllers.
+
+It was noted USB subsystem already has usb-gadget and usb-host triggers
+but they are pretty trivial ones. They indicate activity only and can't
+have ports specified.
+
+In future it may be good idea to consider adding activity support to
+usbport as well. This should allow switching to this more generic driver
+and maybe marking old ones as obsolete.
+This can be implemented with another sysfs file for setting mode. The
+default mode wouldn't change so there won't be ABI breakage and so such
+feature can be safely implemented later.
+
+There was also an idea of supporting other devices (PCI, SDIO, etc.) but
+as this driver already contains some USB specific code (and will get
+more) these should be probably separated drivers (triggers).
+
+Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ .../ABI/testing/sysfs-class-led-trigger-usbport | 12 +
+ Documentation/leds/ledtrig-usbport.txt | 41 +++
+ drivers/usb/core/Kconfig | 8 +
+ drivers/usb/core/Makefile | 2 +
+ drivers/usb/core/ledtrig-usbport.c | 314 +++++++++++++++++++++
+ 5 files changed, 377 insertions(+)
+ create mode 100644 Documentation/ABI/testing/sysfs-class-led-trigger-usbport
+ create mode 100644 Documentation/leds/ledtrig-usbport.txt
+ create mode 100644 drivers/usb/core/ledtrig-usbport.c
+
+--- /dev/null
++++ b/Documentation/ABI/testing/sysfs-class-led-trigger-usbport
+@@ -0,0 +1,12 @@
++What: /sys/class/leds/<led>/ports/<port>
++Date: September 2016
++KernelVersion: 4.9
++Contact: linux-leds@vger.kernel.org
++ linux-usb@vger.kernel.org
++Description:
++ Every dir entry represents a single USB port that can be
++ selected for the USB port trigger. Selecting ports makes trigger
++ observing them for any connected devices and lighting on LED if
++ there are any.
++ Echoing "1" value selects USB port. Echoing "0" unselects it.
++ Current state can be also read.
+--- /dev/null
++++ b/Documentation/leds/ledtrig-usbport.txt
+@@ -0,0 +1,41 @@
++USB port LED trigger
++====================
++
++This LED trigger can be used for signalling to the 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 selecting USB ports that should be observed. All available ones are
++listed as separated entries in a "ports" subdirectory. Selecting is handled by
++echoing "1" to a chosen port.
++
++Please note that this trigger allows selecting multiple USB ports for a single
++LED. This can be useful in two cases:
++
++1) Device with single USB LED and few physical ports
++
++In such a 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 may have one controller per PHY standard. E.g. USB 3.0 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 sysfs attributes to the LED that are documented in:
++Documentation/ABI/testing/sysfs-class-led-trigger-usbport
++
++Example use-case:
++
++ echo usbport > trigger
++ echo 1 > ports/usb1-port1
++ echo 1 > ports/usb2-port1
++ cat ports/usb1-port1
++ echo 0 > ports/usb1-port1
+--- a/drivers/usb/core/Kconfig
++++ b/drivers/usb/core/Kconfig
+@@ -84,3 +84,10 @@ config USB_OTG_FSM
+ Implements OTG Finite State Machine as specified in On-The-Go
+ and Embedded Host Supplement to the USB Revision 2.0 Specification.
+
++config USB_LEDS_TRIGGER_USBPORT
++ tristate "USB port LED trigger"
++ depends on USB && LEDS_TRIGGERS
++ help
++ This driver allows LEDs to be controlled by USB events. Enabling this
++ trigger allows specifying list of USB ports that should turn on LED
++ when some USB device gets connected.
+--- a/drivers/usb/core/Makefile
++++ b/drivers/usb/core/Makefile
+@@ -11,3 +11,5 @@ usbcore-$(CONFIG_PCI) += hcd-pci.o
+ usbcore-$(CONFIG_ACPI) += usb-acpi.o
+
+ obj-$(CONFIG_USB) += usbcore.o
++
++obj-$(CONFIG_USB_LEDS_TRIGGER_USBPORT) += ledtrig-usbport.o
+--- /dev/null
++++ b/drivers/usb/core/ledtrig-usbport.c
+@@ -0,0 +1,314 @@
++/*
++ * USB port LED trigger
++ *
++ * Copyright (C) 2016 Rafał Miłecki <rafal@milecki.pl>
++ *
++ * 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/device.h>
++#include <linux/leds.h>
++#include <linux/module.h>
++#include <linux/slab.h>
++#include <linux/usb.h>
++
++struct usbport_trig_data {
++ struct led_classdev *led_cdev;
++ struct list_head ports;
++ struct notifier_block nb;
++ int count; /* Amount of connected matching devices */
++};
++
++struct usbport_trig_port {
++ struct usbport_trig_data *data;
++ struct usb_device *hub;
++ int portnum;
++ char *port_name;
++ bool observed;
++ struct device_attribute attr;
++ struct list_head list;
++};
++
++/***************************************
++ * Helpers
++ ***************************************/
++
++/**
++ * usbport_trig_usb_dev_observed - Check if dev is connected to observed port
++ */
++static bool usbport_trig_usb_dev_observed(struct usbport_trig_data *usbport_data,
++ struct usb_device *usb_dev)
++{
++ struct usbport_trig_port *port;
++
++ if (!usb_dev->parent)
++ return false;
++
++ list_for_each_entry(port, &usbport_data->ports, list) {
++ if (usb_dev->parent == port->hub &&
++ usb_dev->portnum == port->portnum)
++ return port->observed;
++ }
++
++ return false;
++}
++
++static int usbport_trig_usb_dev_check(struct usb_device *usb_dev, void *data)
++{
++ struct usbport_trig_data *usbport_data = data;
++
++ if (usbport_trig_usb_dev_observed(usbport_data, usb_dev))
++ usbport_data->count++;
++
++ return 0;
++}
++
++/**
++ * usbport_trig_update_count - Recalculate amount of connected matching devices
++ */
++static void usbport_trig_update_count(struct usbport_trig_data *usbport_data)
++{
++ struct led_classdev *led_cdev = usbport_data->led_cdev;
++
++ usbport_data->count = 0;
++ usb_for_each_dev(usbport_data, usbport_trig_usb_dev_check);
++ led_cdev->brightness_set(led_cdev,
++ usbport_data->count ? LED_FULL : LED_OFF);
++}
++
++/***************************************
++ * Device attr
++ ***************************************/
++
++static ssize_t usbport_trig_port_show(struct device *dev,
++ struct device_attribute *attr, char *buf)
++{
++ struct usbport_trig_port *port = container_of(attr,
++ struct usbport_trig_port,
++ attr);
++
++ return sprintf(buf, "%d\n", port->observed) + 1;
++}
++
++static ssize_t usbport_trig_port_store(struct device *dev,
++ struct device_attribute *attr,
++ const char *buf, size_t size)
++{
++ struct usbport_trig_port *port = container_of(attr,
++ struct usbport_trig_port,
++ attr);
++
++ if (!strcmp(buf, "0") || !strcmp(buf, "0\n"))
++ port->observed = 0;
++ else if (!strcmp(buf, "1") || !strcmp(buf, "1\n"))
++ port->observed = 1;
++ else
++ return -EINVAL;
++
++ usbport_trig_update_count(port->data);
++
++ return size;
++}
++
++static struct attribute *ports_attrs[] = {
++ NULL,
++};
++static const struct attribute_group ports_group = {
++ .name = "ports",
++ .attrs = ports_attrs,
++};
++
++/***************************************
++ * Adding & removing ports
++ ***************************************/
++
++static int usbport_trig_add_port(struct usbport_trig_data *usbport_data,
++ struct usb_device *usb_dev,
++ const char *hub_name, int portnum)
++{
++ struct led_classdev *led_cdev = usbport_data->led_cdev;
++ struct usbport_trig_port *port;
++ size_t len;
++ int err;
++
++ port = kzalloc(sizeof(*port), GFP_KERNEL);
++ if (!port) {
++ err = -ENOMEM;
++ goto err_out;
++ }
++
++ port->data = usbport_data;
++ port->hub = usb_dev;
++ port->portnum = portnum;
++
++ len = strlen(hub_name) + 8;
++ port->port_name = kzalloc(len, GFP_KERNEL);
++ if (!port->port_name) {
++ err = -ENOMEM;
++ goto err_free_port;
++ }
++ snprintf(port->port_name, len, "%s-port%d", hub_name, portnum);
++
++ port->attr.attr.name = port->port_name;
++ port->attr.attr.mode = S_IRUSR | S_IWUSR;
++ port->attr.show = usbport_trig_port_show;
++ port->attr.store = usbport_trig_port_store;
++
++ err = sysfs_add_file_to_group(&led_cdev->dev->kobj, &port->attr.attr,
++ ports_group.name);
++ if (err)
++ goto err_free_port_name;
++
++ list_add_tail(&port->list, &usbport_data->ports);
++
++ return 0;
++
++err_free_port_name:
++ kfree(port->port_name);
++err_free_port:
++ kfree(port);
++err_out:
++ return err;
++}
++
++static int usbport_trig_add_usb_dev_ports(struct usb_device *usb_dev,
++ void *data)
++{
++ struct usbport_trig_data *usbport_data = data;
++ int i;
++
++ for (i = 1; i <= usb_dev->maxchild; i++)
++ usbport_trig_add_port(usbport_data, usb_dev,
++ dev_name(&usb_dev->dev), i);
++
++ return 0;
++}
++
++static void usbport_trig_remove_port(struct usbport_trig_data *usbport_data,
++ struct usbport_trig_port *port)
++{
++ struct led_classdev *led_cdev = usbport_data->led_cdev;
++
++ list_del(&port->list);
++ sysfs_remove_file_from_group(&led_cdev->dev->kobj, &port->attr.attr,
++ ports_group.name);
++ kfree(port->port_name);
++ kfree(port);
++}
++
++static void usbport_trig_remove_usb_dev_ports(struct usbport_trig_data *usbport_data,
++ struct usb_device *usb_dev)
++{
++ struct usbport_trig_port *port, *tmp;
++
++ list_for_each_entry_safe(port, tmp, &usbport_data->ports, list) {
++ if (port->hub == usb_dev)
++ usbport_trig_remove_port(usbport_data, port);
++ }
++}
++
++/***************************************
++ * Init, exit, etc.
++ ***************************************/
++
++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;
++ struct usb_device *usb_dev = data;
++ bool observed;
++
++ observed = usbport_trig_usb_dev_observed(usbport_data, usb_dev);
++
++ switch (action) {
++ case USB_DEVICE_ADD:
++ usbport_trig_add_usb_dev_ports(usb_dev, usbport_data);
++ if (observed && usbport_data->count++ == 0)
++ led_cdev->brightness_set(led_cdev, LED_FULL);
++ return NOTIFY_OK;
++ case USB_DEVICE_REMOVE:
++ usbport_trig_remove_usb_dev_ports(usbport_data, usb_dev);
++ if (observed && --usbport_data->count == 0)
++ led_cdev->brightness_set(led_cdev, LED_OFF);
++ return NOTIFY_OK;
++ }
++
++ return NOTIFY_DONE;
++}
++
++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;
++
++ /* List of ports */
++ INIT_LIST_HEAD(&usbport_data->ports);
++ err = sysfs_create_group(&led_cdev->dev->kobj, &ports_group);
++ if (err)
++ goto err_free;
++ usb_for_each_dev(usbport_data, usbport_trig_add_usb_dev_ports);
++
++ /* Notifications */
++ usbport_data->nb.notifier_call = usbport_trig_notify,
++ led_cdev->trigger_data = usbport_data;
++ usb_register_notify(&usbport_data->nb);
++
++ led_cdev->activated = true;
++ return;
++
++err_free:
++ kfree(usbport_data);
++}
++
++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;
++
++ list_for_each_entry_safe(port, tmp, &usbport_data->ports, list) {
++ usbport_trig_remove_port(usbport_data, port);
++ }
++
++ usb_unregister_notify(&usbport_data->nb);
++
++ sysfs_remove_group(&led_cdev->dev->kobj, &ports_group);
++
++ 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@milecki.pl>");
++MODULE_DESCRIPTION("USB port trigger");
++MODULE_LICENSE("GPL v2");
diff --git a/target/linux/generic/patches-4.4/084-usb-core-Introduce-a-USB-port-LED-trigger.patch b/target/linux/generic/patches-4.4/084-usb-core-Introduce-a-USB-port-LED-trigger.patch
new file mode 100644
index 0000000000..68039f67bb
--- /dev/null
+++ b/target/linux/generic/patches-4.4/084-usb-core-Introduce-a-USB-port-LED-trigger.patch
@@ -0,0 +1,465 @@
+From 0f247626cbbfa2010d2b86fdee652605e084e248 Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <rafal@milecki.pl>
+Date: Fri, 16 Sep 2016 16:13:48 +0200
+Subject: [PATCH] usb: core: Introduce a USB port LED trigger
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+This commit adds a new trigger responsible for turning on LED when USB
+device gets connected to the selected USB port. This can can useful for
+various home routers that have USB port(s) and a proper LED telling user
+a device is connected.
+
+The trigger gets its documentation file but basically it just requires
+enabling it and selecting USB ports (e.g. echo 1 > ports/usb1-1).
+
+There was a long discussion on design of this driver. Its current state
+is a result of picking them most adjustable solution as others couldn't
+handle all cases.
+
+1) It wasn't possible for the driver to register separated trigger for
+ each USB port. Some physical USB ports are handled by more than one
+ controller and so by more than one USB port. E.g. USB 2.0 physical
+ port may be handled by OHCI's port and EHCI's port.
+ It's also not possible to assign more than 1 trigger to a single LED
+ and implementing such feature would be tricky due to syncing triggers
+ and sysfs conflicts with old triggers.
+
+2) Another idea was to register trigger per USB hub. This wouldn't allow
+ handling devices with multiple USB LEDs and controllers (hubs)
+ controlling more than 1 physical port. It's common for hubs to have
+ few ports and each may have its own LED.
+
+This final trigger is highly flexible. It allows selecting any USB ports
+for any LED. It was also modified (comparing to the initial version) to
+allow choosing ports rather than having user /guess/ proper names. It
+was successfully tested on SmartRG SR400ac which has 3 USB LEDs,
+2 physical ports and 3 controllers.
+
+It was noted USB subsystem already has usb-gadget and usb-host triggers
+but they are pretty trivial ones. They indicate activity only and can't
+have ports specified.
+
+In future it may be good idea to consider adding activity support to
+usbport as well. This should allow switching to this more generic driver
+and maybe marking old ones as obsolete.
+This can be implemented with another sysfs file for setting mode. The
+default mode wouldn't change so there won't be ABI breakage and so such
+feature can be safely implemented later.
+
+There was also an idea of supporting other devices (PCI, SDIO, etc.) but
+as this driver already contains some USB specific code (and will get
+more) these should be probably separated drivers (triggers).
+
+Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ .../ABI/testing/sysfs-class-led-trigger-usbport | 12 +
+ Documentation/leds/ledtrig-usbport.txt | 41 +++
+ drivers/usb/core/Kconfig | 8 +
+ drivers/usb/core/Makefile | 2 +
+ drivers/usb/core/ledtrig-usbport.c | 314 +++++++++++++++++++++
+ 5 files changed, 377 insertions(+)
+ create mode 100644 Documentation/ABI/testing/sysfs-class-led-trigger-usbport
+ create mode 100644 Documentation/leds/ledtrig-usbport.txt
+ create mode 100644 drivers/usb/core/ledtrig-usbport.c
+
+--- /dev/null
++++ b/Documentation/ABI/testing/sysfs-class-led-trigger-usbport
+@@ -0,0 +1,12 @@
++What: /sys/class/leds/<led>/ports/<port>
++Date: September 2016
++KernelVersion: 4.9
++Contact: linux-leds@vger.kernel.org
++ linux-usb@vger.kernel.org
++Description:
++ Every dir entry represents a single USB port that can be
++ selected for the USB port trigger. Selecting ports makes trigger
++ observing them for any connected devices and lighting on LED if
++ there are any.
++ Echoing "1" value selects USB port. Echoing "0" unselects it.
++ Current state can be also read.
+--- /dev/null
++++ b/Documentation/leds/ledtrig-usbport.txt
+@@ -0,0 +1,41 @@
++USB port LED trigger
++====================
++
++This LED trigger can be used for signalling to the 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 selecting USB ports that should be observed. All available ones are
++listed as separated entries in a "ports" subdirectory. Selecting is handled by
++echoing "1" to a chosen port.
++
++Please note that this trigger allows selecting multiple USB ports for a single
++LED. This can be useful in two cases:
++
++1) Device with single USB LED and few physical ports
++
++In such a 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 may have one controller per PHY standard. E.g. USB 3.0 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 sysfs attributes to the LED that are documented in:
++Documentation/ABI/testing/sysfs-class-led-trigger-usbport
++
++Example use-case:
++
++ echo usbport > trigger
++ echo 1 > ports/usb1-port1
++ echo 1 > ports/usb2-port1
++ cat ports/usb1-port1
++ echo 0 > ports/usb1-port1
+--- a/drivers/usb/core/Kconfig
++++ b/drivers/usb/core/Kconfig
+@@ -103,3 +103,11 @@ config USB_ULPI_BUS
+
+ To compile this driver as a module, choose M here: the module will
+ be called ulpi.
++
++config USB_LEDS_TRIGGER_USBPORT
++ tristate "USB port LED trigger"
++ depends on USB && LEDS_TRIGGERS
++ help
++ This driver allows LEDs to be controlled by USB events. Enabling this
++ trigger allows specifying list of USB ports that should turn on LED
++ when some USB device gets connected.
+--- a/drivers/usb/core/Makefile
++++ b/drivers/usb/core/Makefile
+@@ -11,3 +11,5 @@ usbcore-$(CONFIG_PCI) += hcd-pci.o
+ usbcore-$(CONFIG_ACPI) += usb-acpi.o
+
+ obj-$(CONFIG_USB) += usbcore.o
++
++obj-$(CONFIG_USB_LEDS_TRIGGER_USBPORT) += ledtrig-usbport.o
+--- /dev/null
++++ b/drivers/usb/core/ledtrig-usbport.c
+@@ -0,0 +1,314 @@
++/*
++ * USB port LED trigger
++ *
++ * Copyright (C) 2016 Rafał Miłecki <rafal@milecki.pl>
++ *
++ * 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/device.h>
++#include <linux/leds.h>
++#include <linux/module.h>
++#include <linux/slab.h>
++#include <linux/usb.h>
++
++struct usbport_trig_data {
++ struct led_classdev *led_cdev;
++ struct list_head ports;
++ struct notifier_block nb;
++ int count; /* Amount of connected matching devices */
++};
++
++struct usbport_trig_port {
++ struct usbport_trig_data *data;
++ struct usb_device *hub;
++ int portnum;
++ char *port_name;
++ bool observed;
++ struct device_attribute attr;
++ struct list_head list;
++};
++
++/***************************************
++ * Helpers
++ ***************************************/
++
++/**
++ * usbport_trig_usb_dev_observed - Check if dev is connected to observed port
++ */
++static bool usbport_trig_usb_dev_observed(struct usbport_trig_data *usbport_data,
++ struct usb_device *usb_dev)
++{
++ struct usbport_trig_port *port;
++
++ if (!usb_dev->parent)
++ return false;
++
++ list_for_each_entry(port, &usbport_data->ports, list) {
++ if (usb_dev->parent == port->hub &&
++ usb_dev->portnum == port->portnum)
++ return port->observed;
++ }
++
++ return false;
++}
++
++static int usbport_trig_usb_dev_check(struct usb_device *usb_dev, void *data)
++{
++ struct usbport_trig_data *usbport_data = data;
++
++ if (usbport_trig_usb_dev_observed(usbport_data, usb_dev))
++ usbport_data->count++;
++
++ return 0;
++}
++
++/**
++ * usbport_trig_update_count - Recalculate amount of connected matching devices
++ */
++static void usbport_trig_update_count(struct usbport_trig_data *usbport_data)
++{
++ struct led_classdev *led_cdev = usbport_data->led_cdev;
++
++ usbport_data->count = 0;
++ usb_for_each_dev(usbport_data, usbport_trig_usb_dev_check);
++ led_cdev->brightness_set(led_cdev,
++ usbport_data->count ? LED_FULL : LED_OFF);
++}
++
++/***************************************
++ * Device attr
++ ***************************************/
++
++static ssize_t usbport_trig_port_show(struct device *dev,
++ struct device_attribute *attr, char *buf)
++{
++ struct usbport_trig_port *port = container_of(attr,
++ struct usbport_trig_port,
++ attr);
++
++ return sprintf(buf, "%d\n", port->observed) + 1;
++}
++
++static ssize_t usbport_trig_port_store(struct device *dev,
++ struct device_attribute *attr,
++ const char *buf, size_t size)
++{
++ struct usbport_trig_port *port = container_of(attr,
++ struct usbport_trig_port,
++ attr);
++
++ if (!strcmp(buf, "0") || !strcmp(buf, "0\n"))
++ port->observed = 0;
++ else if (!strcmp(buf, "1") || !strcmp(buf, "1\n"))
++ port->observed = 1;
++ else
++ return -EINVAL;
++
++ usbport_trig_update_count(port->data);
++
++ return size;
++}
++
++static struct attribute *ports_attrs[] = {
++ NULL,
++};
++static const struct attribute_group ports_group = {
++ .name = "ports",
++ .attrs = ports_attrs,
++};
++
++/***************************************
++ * Adding & removing ports
++ ***************************************/
++
++static int usbport_trig_add_port(struct usbport_trig_data *usbport_data,
++ struct usb_device *usb_dev,
++ const char *hub_name, int portnum)
++{
++ struct led_classdev *led_cdev = usbport_data->led_cdev;
++ struct usbport_trig_port *port;
++ size_t len;
++ int err;
++
++ port = kzalloc(sizeof(*port), GFP_KERNEL);
++ if (!port) {
++ err = -ENOMEM;
++ goto err_out;
++ }
++
++ port->data = usbport_data;
++ port->hub = usb_dev;
++ port->portnum = portnum;
++
++ len = strlen(hub_name) + 8;
++ port->port_name = kzalloc(len, GFP_KERNEL);
++ if (!port->port_name) {
++ err = -ENOMEM;
++ goto err_free_port;
++ }
++ snprintf(port->port_name, len, "%s-port%d", hub_name, portnum);
++
++ port->attr.attr.name = port->port_name;
++ port->attr.attr.mode = S_IRUSR | S_IWUSR;
++ port->attr.show = usbport_trig_port_show;
++ port->attr.store = usbport_trig_port_store;
++
++ err = sysfs_add_file_to_group(&led_cdev->dev->kobj, &port->attr.attr,
++ ports_group.name);
++ if (err)
++ goto err_free_port_name;
++
++ list_add_tail(&port->list, &usbport_data->ports);
++
++ return 0;
++
++err_free_port_name:
++ kfree(port->port_name);
++err_free_port:
++ kfree(port);
++err_out:
++ return err;
++}
++
++static int usbport_trig_add_usb_dev_ports(struct usb_device *usb_dev,
++ void *data)
++{
++ struct usbport_trig_data *usbport_data = data;
++ int i;
++
++ for (i = 1; i <= usb_dev->maxchild; i++)
++ usbport_trig_add_port(usbport_data, usb_dev,
++ dev_name(&usb_dev->dev), i);
++
++ return 0;
++}
++
++static void usbport_trig_remove_port(struct usbport_trig_data *usbport_data,
++ struct usbport_trig_port *port)
++{
++ struct led_classdev *led_cdev = usbport_data->led_cdev;
++
++ list_del(&port->list);
++ sysfs_remove_file_from_group(&led_cdev->dev->kobj, &port->attr.attr,
++ ports_group.name);
++ kfree(port->port_name);
++ kfree(port);
++}
++
++static void usbport_trig_remove_usb_dev_ports(struct usbport_trig_data *usbport_data,
++ struct usb_device *usb_dev)
++{
++ struct usbport_trig_port *port, *tmp;
++
++ list_for_each_entry_safe(port, tmp, &usbport_data->ports, list) {
++ if (port->hub == usb_dev)
++ usbport_trig_remove_port(usbport_data, port);
++ }
++}
++
++/***************************************
++ * Init, exit, etc.
++ ***************************************/
++
++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;
++ struct usb_device *usb_dev = data;
++ bool observed;
++
++ observed = usbport_trig_usb_dev_observed(usbport_data, usb_dev);
++
++ switch (action) {
++ case USB_DEVICE_ADD:
++ usbport_trig_add_usb_dev_ports(usb_dev, usbport_data);
++ if (observed && usbport_data->count++ == 0)
++ led_cdev->brightness_set(led_cdev, LED_FULL);
++ return NOTIFY_OK;
++ case USB_DEVICE_REMOVE:
++ usbport_trig_remove_usb_dev_ports(usbport_data, usb_dev);
++ if (observed && --usbport_data->count == 0)
++ led_cdev->brightness_set(led_cdev, LED_OFF);
++ return NOTIFY_OK;
++ }
++
++ return NOTIFY_DONE;
++}
++
++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;
++
++ /* List of ports */
++ INIT_LIST_HEAD(&usbport_data->ports);
++ err = sysfs_create_group(&led_cdev->dev->kobj, &ports_group);
++ if (err)
++ goto err_free;
++ usb_for_each_dev(usbport_data, usbport_trig_add_usb_dev_ports);
++
++ /* Notifications */
++ usbport_data->nb.notifier_call = usbport_trig_notify,
++ led_cdev->trigger_data = usbport_data;
++ usb_register_notify(&usbport_data->nb);
++
++ led_cdev->activated = true;
++ return;
++
++err_free:
++ kfree(usbport_data);
++}
++
++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;
++
++ list_for_each_entry_safe(port, tmp, &usbport_data->ports, list) {
++ usbport_trig_remove_port(usbport_data, port);
++ }
++
++ usb_unregister_notify(&usbport_data->nb);
++
++ sysfs_remove_group(&led_cdev->dev->kobj, &ports_group);
++
++ 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@milecki.pl>");
++MODULE_DESCRIPTION("USB port trigger");
++MODULE_LICENSE("GPL v2");