Commit 201af55d authored by Jon Flatley's avatar Jon Flatley Committed by Greg Kroah-Hartman
Browse files

usb: core: added uevent for over-current 



After commit 1cbd53c8 ("usb: core: introduce per-port over-current
counters") usb ports expose a sysfs value 'over_current_count'
to user space. This value on its own is not very useful as it requires
manual polling.

As a solution, fire a udev event from the usb hub device that specifies
the values 'OVER_CURRENT_PORT' and 'OVER_CURRENT_COUNT' that indicate
the path of the usb port where the over-current event occurred and the
value of 'over_current_count' in sysfs. Additionally, call
sysfs_notify() so the sysfs value supports poll().

Signed-off-by: default avatarJon Flatley <jflat@chromium.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent ea3b4d55

Documentation/ABI/testing/sysfs-bus-usb

+8 −1
Original line number Diff line number Diff line
@@ -219,7 +219,14 @@ Description: 
		ports and report them to the kernel. This attribute is to expose

		the number of over-current situation occurred on a specific port

		to user space. This file will contain an unsigned 32 bit value

		which wraps to 0 after its maximum is reached.

		which wraps to 0 after its maximum is reached. This file supports

		poll() for monitoring changes to this value in user space.



		Any time this value changes the corresponding hub device will send a

		udev event with the following attributes:



		OVER_CURRENT_PORT=/sys/bus/usb/devices/.../(hub interface)/portX

		OVER_CURRENT_COUNT=[current value of this sysfs attribute]



What:		/sys/bus/usb/devices/.../(hub interface)/portX/usb3_lpm_permit

Date:		November 2015

drivers/usb/core/hub.c

+36 −0
Original line number Diff line number Diff line
@@ -28,6 +28,7 @@ 
#include <linux/mutex.h>

#include <linux/random.h>

#include <linux/pm_qos.h>

#include <linux/kobject.h>



#include <linux/uaccess.h>

#include <asm/byteorder.h>
@@ -5147,6 +5148,40 @@ static void hub_port_connect_change(struct usb_hub *hub, int port1, 
	usb_lock_port(port_dev);

}



/* Handle notifying userspace about hub over-current events */

static void port_over_current_notify(struct usb_port *port_dev)

{

	static char *envp[] = { NULL, NULL, NULL };

	struct device *hub_dev;

	char *port_dev_path;



	sysfs_notify(&port_dev->dev.kobj, NULL, "over_current_count");



	hub_dev = port_dev->dev.parent;



	if (!hub_dev)

		return;



	port_dev_path = kobject_get_path(&port_dev->dev.kobj, GFP_KERNEL);

	if (!port_dev_path)

		return;



	envp[0] = kasprintf(GFP_KERNEL, "OVER_CURRENT_PORT=%s", port_dev_path);

	if (!envp[0])

		return;



	envp[1] = kasprintf(GFP_KERNEL, "OVER_CURRENT_COUNT=%u",

			port_dev->over_current_count);

	if (!envp[1])

		goto exit;



	kobject_uevent_env(&hub_dev->kobj, KOBJ_CHANGE, envp);



	kfree(envp[1]);

exit:

	kfree(envp[0]);

}



static void port_event(struct usb_hub *hub, int port1)

		__must_hold(&port_dev->status_lock)

{
@@ -5189,6 +5224,7 @@ static void port_event(struct usb_hub *hub, int port1) 
	if (portchange & USB_PORT_STAT_C_OVERCURRENT) {

		u16 status = 0, unused;

		port_dev->over_current_count++;

		port_over_current_notify(port_dev);



		dev_dbg(&port_dev->dev, "over-current change #%u\n",

			port_dev->over_current_count);

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