text: // SPDX-License-Identifier: GPL-2.0
  /*
   * drivers/usb/generic.c - generic driver for USB devices (not interfaces)
   *
   * (C) Copyright 2005 Greg Kroah-Hartman <gregkh@suse.de>
   *
   * based on drivers/usb/usb.c which had the following copyrights:
   *	(C) Copyright Linus Torvalds 1999
   *	(C) Copyright Johannes Erdfelt 1999-2001
   *	(C) Copyright Andreas Gal 1999
   *	(C) Copyright Gregory P. Smith 1999
   *	(C) Copyright Deti Fliegl 1999 (new USB architecture)
   *	(C) Copyright Randy Dunlap 2000
   *	(C) Copyright David Brownell 2000-2004
   *	(C) Copyright Yggdrasil Computing, Inc. 2000
   *		(usb_device_id matching changes by Adam J. Richter)
   *	(C) Copyright Greg Kroah-Hartman 2002-2003
   *
   * Released under the GPLv2 only.
   */
  
  #include <linux/usb.h>
  #include <linux/usb/hcd.h>
  #include <uapi/linux/usb/audio.h>
  #include "usb.h"
  
  static inline const char *plural(int n)
  {
  	return (n == 1 ? "" : "s");
  }
  
  static int is_rndis(struct usb_interface_descriptor *desc)
  {
  	return desc->bInterfaceClass == USB_CLASS_COMM
  		&& desc->bInterfaceSubClass == 2
  		&& desc->bInterfaceProtocol == 0xff;
  }
  
  static int is_activesync(struct usb_interface_descriptor *desc)
  {
  	return desc->bInterfaceClass == USB_CLASS_MISC
  		&& desc->bInterfaceSubClass == 1
  		&& desc->bInterfaceProtocol == 1;
  }
  
  static bool is_audio(struct usb_interface_descriptor *desc)
  {
  	return desc->bInterfaceClass == USB_CLASS_AUDIO;
  }
  
  static bool is_uac3_config(struct usb_interface_descriptor *desc)
  {
  	return desc->bInterfaceProtocol == UAC_VERSION_3;
  }
  
  int usb_choose_configuration(struct usb_device *udev)
  {
  	int i;
  	int num_configs;
  	int insufficient_power = 0;
  	struct usb_host_config *c, *best;
  
  	if (usb_device_is_owned(udev))
  		return 0;
  
  	best = NULL;
  	c = udev->config;
  	num_configs = udev->descriptor.bNumConfigurations;
  	for (i = 0; i < num_configs; (i++, c++)) {
  		struct usb_interface_descriptor	*desc = NULL;
  
  		/* It's possible that a config has no interfaces! */
  		if (c->desc.bNumInterfaces > 0)
  			desc = &c->intf_cache[0]->altsetting->desc;
  
  		/*
  		 * HP's USB bus-powered keyboard has only one configuration
  		 * and it claims to be self-powered; other devices may have
  		 * similar errors in their descriptors.  If the next test
  		 * were allowed to execute, such configurations would always
  		 * be rejected and the devices would not work as expected.
  		 * In the meantime, we run the risk of selecting a config
  		 * that requires external power at a time when that power
  		 * isn't available.  It seems to be the lesser of two evils.
  		 *
  		 * Bugzilla #6448 reports a device that appears to crash
  		 * when it receives a GET_DEVICE_STATUS request!  We don't
  		 * have any other way to tell whether a device is self-powered,
  		 * but since we don't use that information anywhere but here,
  		 * the call has been removed.
  		 *
  		 * Maybe the GET_DEVICE_STATUS call and the test below can
  		 * be reinstated when device firmwares become more reliable.
  		 * Don't hold your breath.
  		 */
  #if 0
  		/* Rule out self-powered configs for a bus-powered device */
  		if (bus_powered && (c->desc.bmAttributes &
  					USB_CONFIG_ATT_SELFPOWER))
  			continue;
  #endif
  
  		/*
  		 * The next test may not be as effective as it should be.
  		 * Some hubs have errors in their descriptor, claiming
  		 * to be self-powered when they are really bus-powered.
  		 * We will overestimate the amount of current such hubs
  		 * make available for each port.
  		 *
  		 * This is a fairly benign sort of failure.  It won't
  		 * cause us to reject configurations that we should have
  		 * accepted.
  		 */
  
  		/* Rule out configs that draw too much bus current */
  		if (usb_get_max_power(udev, c) > udev->bus_mA) {
  			insufficient_power++;
  			continue;
  		}
  
  		/* When the first config's first interface is one of Microsoft's
  		 * pet nonstandard Ethernet-over-USB protocols, ignore it unless
  		 * this kernel has enabled the necessary host side driver.
  		 * But: Don't ignore it if it's the only config.
  		 */
  		if (i == 0 && num_configs > 1 && desc &&
  				(is_rndis(desc) || is_activesync(desc))) {
  #if !defined(CONFIG_USB_NET_RNDIS_HOST) && !defined(CONFIG_USB_NET_RNDIS_HOST_MODULE)
  			continue;
  #else
  			best = c;
  #endif
  		}
  
  		/*
  		 * Select first configuration as default for audio so that
  		 * devices that don't comply with UAC3 protocol are supported.
  		 * But, still iterate through other configurations and
  		 * select UAC3 compliant config if present.
  		 */
  		if (i == 0 && num_configs > 1 && desc && is_audio(desc)) {
  			best = c;
  			continue;
  		}
  
  		if (i > 0 && desc && is_audio(desc) && is_uac3_config(desc)) {
  			best = c;
  			break;
  		}
  
  		/* From the remaining configs, choose the first one whose
  		 * first interface is for a non-vendor-specific class.
  		 * Reason: Linux is more likely to have a class driver
  		 * than a vendor-specific driver. */
  		else if (udev->descriptor.bDeviceClass !=
  						USB_CLASS_VENDOR_SPEC &&
  				(desc && desc->bInterfaceClass !=
  						USB_CLASS_VENDOR_SPEC)) {
  			best = c;
  			break;
  		}
  
  		/* If all the remaining configs are vendor-specific,
  		 * choose the first one. */
  		else if (!best)
  			best = c;
  	}
  
  	if (insufficient_power > 0)
  		dev_info(&udev->dev, "rejected %d configuration%s "
  			"due to insufficient available bus power\n",
  			insufficient_power, plural(insufficient_power));
  
  	if (best) {
  		i = best->desc.bConfigurationValue;
  		dev_dbg(&udev->dev,
  			"configuration #%d chosen from %d choice%s\n",
  			i, num_configs, plural(num_configs));
  	} else {
  		i = -1;
  		dev_warn(&udev->dev,
  			"no configuration chosen from %d choice%s\n",
  			num_configs, plural(num_configs));
  	}
  	return i;
  }
  EXPORT_SYMBOL_GPL(usb_choose_configuration);
  
  static int generic_probe(struct usb_device *udev)
  {
  	int err, c;
  
  	/* Choose and set the configuration.  This registers the interfaces
  	 * with the driver core and lets interface drivers bind to them.
  	 */
  	if (udev->authorized == 0)
  		dev_err(&udev->dev, "Device is not authorized for usage\n");
  	else {
  		c = usb_choose_configuration(udev);
  		if (c >= 0) {
  			err = usb_set_configuration(udev, c);
  			if (err && err != -ENODEV) {
  				dev_err(&udev->dev, "can't set config #%d, error %d\n",
  					c, err);
  				/* This need not be fatal.  The user can try to
  				 * set other configurations. */
  			}
  		}
  	}
  	/* USB device state == configured ... usable */
  	usb_notify_add_device(udev);
  
  	return 0;
  }
  
  static void generic_disconnect(struct usb_device *udev)
  {
  	usb_notify_remove_device(udev);
  
  	/* if this is only an unbind, not a physical disconnect, then
  	 * unconfigure the device */
  	if (udev->actconfig)
  		usb_set_configuration(udev, -1);
  }
  
  #ifdef	CONFIG_PM
  
  static int generic_suspend(struct usb_device *udev, pm_message_t msg)
  {
  	int rc;
  
  	/* Normal USB devices suspend through their upstream port.
  	 * Root hubs don't have upstream ports to suspend,
  	 * so we have to shut down their downstream HC-to-USB
  	 * interfaces manually by doing a bus (or "global") suspend.
  	 */
  	if (!udev->parent)
  		rc = hcd_bus_suspend(udev, msg);
  
  	/*
  	 * Non-root USB2 devices don't need to do anything for FREEZE
  	 * or PRETHAW. USB3 devices don't support global suspend and
  	 * needs to be selectively suspended.
  	 */
  	else if ((msg.event == PM_EVENT_FREEZE || msg.event == PM_EVENT_PRETHAW)
  		 && (udev->speed < USB_SPEED_SUPER))
  		rc = 0;
  	else
  		rc = usb_port_suspend(udev, msg);
  
  	return rc;
  }
  
  static int generic_resume(struct usb_device *udev, pm_message_t msg)
  {
  	int rc;
  
  	/* Normal USB devices resume/reset through their upstream port.
  	 * Root hubs don't have upstream ports to resume or reset,
  	 * so we have to start up their downstream HC-to-USB
  	 * interfaces manually by doing a bus (or "global") resume.
  	 */
  	if (!udev->parent)
  		rc = hcd_bus_resume(udev, msg);
  	else
  		rc = usb_port_resume(udev, msg);
  	return rc;
  }
  
  #endif	/* CONFIG_PM */
  
  struct usb_device_driver usb_generic_driver = {
  	.name =	"usb",
  	.probe = generic_probe,
  	.disconnect = generic_disconnect,
  #ifdef	CONFIG_PM
  	.suspend = generic_suspend,
  	.resume = generic_resume,
  #endif
  	.supports_autosuspend = 1,
  };
  