Add support for getting device information from opened device on Linux

[kirisauce]

Hi! I'm doing some works on Termux. Termux provides a command termux-usb for accessing USB device. But it give me only a file descriptor, and I need to get some basic information about the device. So I did some works to get information about the device itself from opened device.

New Public APIs

• fn Device::get_device_descriptor()
• fn Device::get_device_info()
• struct descriptors::DeviceDescriptor

I'm sorry for the mistakes I made.

Changelog

20250108-1

• Removed pub fn device::Device::get_device_info
• Removed pub fn descriptors::DeviceDescriptor::speed
• Removed fn descriptors::DeviceDescriptor::format_usb_version
• Removed fn platform::linux_usbfs::device::LinuxDevice::get_busnum_and_devnum
• Removed fn enumeration::Speed::from_usb_version
• Renamed fn platform::linux_usbfs::device::LinuxDevice::get_descriptors to descriptors
• Adjusted Debug implementation for descriptors::DeviceDescriptor to keep the same output format

Note: The type descriptors::DeviceDescriptor is defined as USB standard device descriptor.

[kevinmehall]

Device descriptor is a good addition. It would be nice to have it on all platforms, but that can be added later if you don't have easy access to macOS and Windows.

I'm not sure the API to get DeviceInfo is a good idea. Pretty much all the useful information is exposed in the device descriptor here.

For Android, using Java APIs to enumerate devices to populate DeviceInfo before opening a device is probably a better idea: #86 (comment)

[kevinmehall]

You can't assume the speed from the USB version. Plenty of Full Speed devices devices specify 0x0200, or 0x0210 if they support BOS. I'd rather return None than take a wild guess like this.

[kirisauce]

Thank your for the correction! I will change them later.

[kirisauce]

@kevinmehall Besides, I'm trying implementing a new feature that could get device speed from an opened device through an ioctl USBDEVFS_GET_SPEED. But one of its return value USB_SPEED_WIRELESS (defined in linux/usb/ch9.h) has no corresponding value in enumeration::Speed. According to the comment, it is called usb2.5, and should it be Speed::Full, Speed::High or others?

enum usb_device_speed {
	USB_SPEED_UNKNOWN = 0,			/* enumerating */
	USB_SPEED_LOW, USB_SPEED_FULL,		/* usb 1.1 */
	USB_SPEED_HIGH,				/* usb 2.0 */
	USB_SPEED_WIRELESS,			/* wireless (usb 2.5) */
	USB_SPEED_SUPER,			/* usb 3.0 */
	USB_SPEED_SUPER_PLUS,			/* usb 3.1 */
};

[kevinmehall]

That seems like a better approach. It should probably return Option to cover the case of newer speeds introduced that we don't know about yet, or failure of the ioctl, and you can use that to leave USB_SPEED_WIRELESS undefined. Support for Wireless USB was removed in kernel 5.7 and was long dead before that.