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usb: core: added uevent for over-current

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After commit 1cbd53c8cd ("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: Jon Flatley <jflat@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jon Flatley 2018-09-20 10:17:54 -07:00 committed by Greg Kroah-Hartman
parent ea3b4d5523
commit 201af55da8
2 changed files with 44 additions and 1 deletions
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9
Documentation/ABI/testing/sysfs-bus-usb
View File

@ -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

36
drivers/usb/core/hub.c
View File

@ -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);