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7794f486ed
It has been requested that usbfs should implement runtime power management, instead of forcing the device to remain at full power as long as the device file is open. This patch introduces that new feature. It does so by adding three new usbfs ioctls: USBDEVFS_FORBID_SUSPEND: Prevents the device from going into runtime suspend (and causes a resume if the device is already suspended). USBDEVFS_ALLOW_SUSPEND: Allows the device to go into runtime suspend. Some time may elapse before the device actually is suspended, depending on things like the autosuspend delay. USBDEVFS_WAIT_FOR_RESUME: Blocks until the call is interrupted by a signal or at least one runtime resume has occurred since the most recent ALLOW_SUSPEND ioctl call (which may mean immediately, even if the device is currently suspended). In the latter case, the device is prevented from suspending again just as if FORBID_SUSPEND was called before the ioctl returns. For backward compatibility, when the device file is first opened runtime suspends are forbidden. The userspace program can then allow suspends whenever it wants, and either resume the device directly (by forbidding suspends again) or wait for a resume from some other source (such as a remote wakeup). URBs submitted to a suspended device will fail or will complete with an appropriate error code. This combination of ioctls is sufficient for user programs to have nearly the same degree of control over a device's runtime power behavior as kernel drivers do. Still lacking is documentation for the new ioctls. I intend to add it later, after the existing documentation for the usbfs userspace API is straightened out into a reasonable form. Suggested-by: Mayuresh Kulkarni <mkulkarni@opensource.cirrus.com> Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Link: https://lore.kernel.org/r/Pine.LNX.4.44L0.1908071013220.1514-100000@iolanthe.rowland.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
296 lines
8.2 KiB
C
296 lines
8.2 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* drivers/usb/generic.c - generic driver for USB devices (not interfaces)
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*
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* (C) Copyright 2005 Greg Kroah-Hartman <gregkh@suse.de>
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*
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* based on drivers/usb/usb.c which had the following copyrights:
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* (C) Copyright Linus Torvalds 1999
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* (C) Copyright Johannes Erdfelt 1999-2001
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* (C) Copyright Andreas Gal 1999
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* (C) Copyright Gregory P. Smith 1999
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* (C) Copyright Deti Fliegl 1999 (new USB architecture)
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* (C) Copyright Randy Dunlap 2000
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* (C) Copyright David Brownell 2000-2004
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* (C) Copyright Yggdrasil Computing, Inc. 2000
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* (usb_device_id matching changes by Adam J. Richter)
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* (C) Copyright Greg Kroah-Hartman 2002-2003
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*
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* Released under the GPLv2 only.
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*/
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#include <linux/usb.h>
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#include <linux/usb/hcd.h>
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#include <uapi/linux/usb/audio.h>
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#include "usb.h"
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static inline const char *plural(int n)
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{
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return (n == 1 ? "" : "s");
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}
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static int is_rndis(struct usb_interface_descriptor *desc)
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{
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return desc->bInterfaceClass == USB_CLASS_COMM
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&& desc->bInterfaceSubClass == 2
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&& desc->bInterfaceProtocol == 0xff;
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}
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static int is_activesync(struct usb_interface_descriptor *desc)
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{
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return desc->bInterfaceClass == USB_CLASS_MISC
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&& desc->bInterfaceSubClass == 1
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&& desc->bInterfaceProtocol == 1;
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}
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static bool is_audio(struct usb_interface_descriptor *desc)
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{
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return desc->bInterfaceClass == USB_CLASS_AUDIO;
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}
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static bool is_uac3_config(struct usb_interface_descriptor *desc)
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{
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return desc->bInterfaceProtocol == UAC_VERSION_3;
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}
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int usb_choose_configuration(struct usb_device *udev)
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{
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int i;
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int num_configs;
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int insufficient_power = 0;
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struct usb_host_config *c, *best;
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if (usb_device_is_owned(udev))
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return 0;
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best = NULL;
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c = udev->config;
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num_configs = udev->descriptor.bNumConfigurations;
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for (i = 0; i < num_configs; (i++, c++)) {
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struct usb_interface_descriptor *desc = NULL;
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/* It's possible that a config has no interfaces! */
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if (c->desc.bNumInterfaces > 0)
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desc = &c->intf_cache[0]->altsetting->desc;
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/*
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* HP's USB bus-powered keyboard has only one configuration
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* and it claims to be self-powered; other devices may have
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* similar errors in their descriptors. If the next test
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* were allowed to execute, such configurations would always
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* be rejected and the devices would not work as expected.
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* In the meantime, we run the risk of selecting a config
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* that requires external power at a time when that power
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* isn't available. It seems to be the lesser of two evils.
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*
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* Bugzilla #6448 reports a device that appears to crash
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* when it receives a GET_DEVICE_STATUS request! We don't
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* have any other way to tell whether a device is self-powered,
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* but since we don't use that information anywhere but here,
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* the call has been removed.
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*
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* Maybe the GET_DEVICE_STATUS call and the test below can
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* be reinstated when device firmwares become more reliable.
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* Don't hold your breath.
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*/
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#if 0
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/* Rule out self-powered configs for a bus-powered device */
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if (bus_powered && (c->desc.bmAttributes &
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USB_CONFIG_ATT_SELFPOWER))
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continue;
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#endif
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/*
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* The next test may not be as effective as it should be.
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* Some hubs have errors in their descriptor, claiming
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* to be self-powered when they are really bus-powered.
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* We will overestimate the amount of current such hubs
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* make available for each port.
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*
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* This is a fairly benign sort of failure. It won't
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* cause us to reject configurations that we should have
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* accepted.
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*/
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/* Rule out configs that draw too much bus current */
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if (usb_get_max_power(udev, c) > udev->bus_mA) {
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insufficient_power++;
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continue;
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}
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/*
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* Select first configuration as default for audio so that
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* devices that don't comply with UAC3 protocol are supported.
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* But, still iterate through other configurations and
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* select UAC3 compliant config if present.
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*/
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if (desc && is_audio(desc)) {
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/* Always prefer the first found UAC3 config */
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if (is_uac3_config(desc)) {
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best = c;
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break;
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}
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/* If there is no UAC3 config, prefer the first config */
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else if (i == 0)
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best = c;
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/* Unconditional continue, because the rest of the code
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* in the loop is irrelevant for audio devices, and
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* because it can reassign best, which for audio devices
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* we don't want.
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*/
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continue;
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}
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/* When the first config's first interface is one of Microsoft's
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* pet nonstandard Ethernet-over-USB protocols, ignore it unless
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* this kernel has enabled the necessary host side driver.
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* But: Don't ignore it if it's the only config.
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*/
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if (i == 0 && num_configs > 1 && desc &&
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(is_rndis(desc) || is_activesync(desc))) {
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#if !defined(CONFIG_USB_NET_RNDIS_HOST) && !defined(CONFIG_USB_NET_RNDIS_HOST_MODULE)
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continue;
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#else
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best = c;
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#endif
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}
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/* From the remaining configs, choose the first one whose
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* first interface is for a non-vendor-specific class.
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* Reason: Linux is more likely to have a class driver
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* than a vendor-specific driver. */
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else if (udev->descriptor.bDeviceClass !=
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USB_CLASS_VENDOR_SPEC &&
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(desc && desc->bInterfaceClass !=
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USB_CLASS_VENDOR_SPEC)) {
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best = c;
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break;
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}
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/* If all the remaining configs are vendor-specific,
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* choose the first one. */
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else if (!best)
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best = c;
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}
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if (insufficient_power > 0)
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dev_info(&udev->dev, "rejected %d configuration%s "
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"due to insufficient available bus power\n",
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insufficient_power, plural(insufficient_power));
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if (best) {
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i = best->desc.bConfigurationValue;
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dev_dbg(&udev->dev,
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"configuration #%d chosen from %d choice%s\n",
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i, num_configs, plural(num_configs));
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} else {
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i = -1;
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dev_warn(&udev->dev,
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"no configuration chosen from %d choice%s\n",
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num_configs, plural(num_configs));
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}
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return i;
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}
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EXPORT_SYMBOL_GPL(usb_choose_configuration);
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static int generic_probe(struct usb_device *udev)
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{
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int err, c;
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/* Choose and set the configuration. This registers the interfaces
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* with the driver core and lets interface drivers bind to them.
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*/
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if (udev->authorized == 0)
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dev_err(&udev->dev, "Device is not authorized for usage\n");
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else {
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c = usb_choose_configuration(udev);
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if (c >= 0) {
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err = usb_set_configuration(udev, c);
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if (err && err != -ENODEV) {
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dev_err(&udev->dev, "can't set config #%d, error %d\n",
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c, err);
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/* This need not be fatal. The user can try to
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* set other configurations. */
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}
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}
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}
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/* USB device state == configured ... usable */
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usb_notify_add_device(udev);
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return 0;
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}
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static void generic_disconnect(struct usb_device *udev)
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{
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usb_notify_remove_device(udev);
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/* if this is only an unbind, not a physical disconnect, then
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* unconfigure the device */
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if (udev->actconfig)
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usb_set_configuration(udev, -1);
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}
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#ifdef CONFIG_PM
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static int generic_suspend(struct usb_device *udev, pm_message_t msg)
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{
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int rc;
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/* Normal USB devices suspend through their upstream port.
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* Root hubs don't have upstream ports to suspend,
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* so we have to shut down their downstream HC-to-USB
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* interfaces manually by doing a bus (or "global") suspend.
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*/
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if (!udev->parent)
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rc = hcd_bus_suspend(udev, msg);
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/*
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* Non-root USB2 devices don't need to do anything for FREEZE
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* or PRETHAW. USB3 devices don't support global suspend and
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* needs to be selectively suspended.
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*/
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else if ((msg.event == PM_EVENT_FREEZE || msg.event == PM_EVENT_PRETHAW)
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&& (udev->speed < USB_SPEED_SUPER))
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rc = 0;
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else
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rc = usb_port_suspend(udev, msg);
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if (rc == 0)
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usbfs_notify_suspend(udev);
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return rc;
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}
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static int generic_resume(struct usb_device *udev, pm_message_t msg)
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{
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int rc;
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/* Normal USB devices resume/reset through their upstream port.
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* Root hubs don't have upstream ports to resume or reset,
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* so we have to start up their downstream HC-to-USB
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* interfaces manually by doing a bus (or "global") resume.
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*/
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if (!udev->parent)
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rc = hcd_bus_resume(udev, msg);
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else
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rc = usb_port_resume(udev, msg);
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if (rc == 0)
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usbfs_notify_resume(udev);
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return rc;
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}
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#endif /* CONFIG_PM */
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struct usb_device_driver usb_generic_driver = {
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.name = "usb",
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.probe = generic_probe,
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.disconnect = generic_disconnect,
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#ifdef CONFIG_PM
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.suspend = generic_suspend,
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.resume = generic_resume,
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#endif
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.supports_autosuspend = 1,
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};
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