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usb: core: introduce per-port over-current counters 

For some userspace applications information on the number of
over-current conditions at specific USB hub ports is relevant.

In our case we have a series of USB hardware (using the cp210x driver)
which communicates using a proprietary protocol. These devices sometimes
trigger an over-current situation on some hubs. In case of such an
over-current situation the USB devices offer an interface for reducing
the max used power. As these conditions are quite rare and imply
performance reductions of the device we don't want to reduce the max
power always.

Therefore give user-space applications the possibility to react
adequately by introducing an over_current_counter in the usb port struct
which is exported via sysfs.

Signed-off-by: Richard Leitner <richard.leitner@skidata.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Richard Leitner 2018-03-20 11:17:13 +01:00 committed by Greg Kroah-Hartman
parent e3cb7bde9a
commit 1cbd53c8cd
4 changed files with 24 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
Documentation/ABI/testing/sysfs-bus-usb
View File

@ -189,6 +189,16 @@ Description:
The file will read "hotplug", "wired" and "not used" if the
information is available, and "unknown" otherwise.
What: /sys/bus/usb/devices/.../(hub interface)/portX/over_current_count
Date: February 2018
Contact: Richard Leitner <richard.leitner@skidata.com>
Description:
Most hubs are able to detect over-current situations on their
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.
What: /sys/bus/usb/devices/.../(hub interface)/portX/usb3_lpm_permit
Date: November 2015
Contact: Lu Baolu <baolu.lu@linux.intel.com>

4
drivers/usb/core/hub.c
View File

@ -5104,8 +5104,10 @@ 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++;
dev_dbg(&port_dev->dev, "over-current change\n");
dev_dbg(&port_dev->dev, "over-current change #%u\n",
port_dev->over_current_count);
usb_clear_port_feature(hdev, port1,
USB_PORT_FEAT_C_OVER_CURRENT);
msleep(100); /* Cool down */

1
drivers/usb/core/hub.h
View File

@ -96,6 +96,7 @@ struct usb_port {
enum usb_port_connect_type connect_type;
usb_port_location_t location;
struct mutex status_lock;
u32 over_current_count;
u8 portnum;
unsigned int is_superspeed:1;
unsigned int usb3_lpm_u1_permit:1;

10
drivers/usb/core/port.c
View File

@ -41,6 +41,15 @@ static ssize_t connect_type_show(struct device *dev,
}
static DEVICE_ATTR_RO(connect_type);
static ssize_t over_current_count_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct usb_port *port_dev = to_usb_port(dev);
return sprintf(buf, "%u\n", port_dev->over_current_count);
}
static DEVICE_ATTR_RO(over_current_count);
static ssize_t usb3_lpm_permit_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
@ -109,6 +118,7 @@ static DEVICE_ATTR_RW(usb3_lpm_permit);
static struct attribute *port_dev_attrs[] = {
&dev_attr_connect_type.attr,
&dev_attr_over_current_count.attr,
NULL,
};