From 1cbd53c8cd85a63383a075347abee8f6e3f14fbe Mon Sep 17 00:00:00 2001 From: Richard Leitner Date: Tue, 20 Mar 2018 11:17:13 +0100 Subject: [PATCH] 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 Signed-off-by: Greg Kroah-Hartman --- Documentation/ABI/testing/sysfs-bus-usb | 10 ++++++++++ drivers/usb/core/hub.c | 4 +++- drivers/usb/core/hub.h | 1 + drivers/usb/core/port.c | 10 ++++++++++ 4 files changed, 24 insertions(+), 1 deletion(-) diff --git a/Documentation/ABI/testing/sysfs-bus-usb b/Documentation/ABI/testing/sysfs-bus-usb index 0bd731c..c702c78 100644 --- a/Documentation/ABI/testing/sysfs-bus-usb +++ b/Documentation/ABI/testing/sysfs-bus-usb @@ -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 +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 diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c index ac7bab7..aaeef03 100644 --- a/drivers/usb/core/hub.c +++ b/drivers/usb/core/hub.c @@ -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 */ diff --git a/drivers/usb/core/hub.h b/drivers/usb/core/hub.h index 2a700cc..4dc769e 100644 --- a/drivers/usb/core/hub.h +++ b/drivers/usb/core/hub.h @@ -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; diff --git a/drivers/usb/core/port.c b/drivers/usb/core/port.c index 1a01e9a..6979bde 100644 --- a/drivers/usb/core/port.c +++ b/drivers/usb/core/port.c @@ -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, }; -- 2.7.4