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| author | Elbert Mai <code@elbertmai.com> | 2024-03-04 16:23:01 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-03-05 07:57:23 +0000 |
| commit | 12fc84e8c4288cc8ed5f14a35e077130c2cfece2 (patch) | |
| tree | ed9e39c66293fb2130a02919f8acdd1c1affada5 /Documentation/ABI | |
| parent | a14e6fd1b67799da7da9cc344023bd16aaf0d17d (diff) | |
| download | linux-12fc84e8c4288cc8ed5f14a35e077130c2cfece2.tar.gz | |
usb: Export BOS descriptor to sysfs
Motivation
----------
The binary device object store (BOS) of a USB device consists of the BOS
descriptor followed by a set of device capability descriptors. One that is
of interest to users is the platform descriptor. This contains a 128-bit
UUID and arbitrary data, and it allows parties outside of USB-IF to add
additional metadata about a USB device in a standards-compliant manner.
Notable examples include the WebUSB and Microsoft OS 2.0 descriptors.
The kernel already retrieves and caches the BOS from USB devices if its
bcdUSB is >= 0x0201. Because the BOS is flexible and extensible, we export
the entire BOS to sysfs so users can retrieve whatever device capabilities
they desire, without requiring USB I/O or elevated permissions.
Implementation
--------------
Add bos_descriptors attribute to sysfs. This is a binary file and it works
the same way as the existing descriptors attribute. The file exists only if
the BOS is present in the USB device.
Also create a binary attribute group, so the driver core can handle the
creation of both the descriptors and bos_descriptors attributes in sysfs.
Signed-off-by: Elbert Mai <code@elbertmai.com>
Link: https://lore.kernel.org/r/20240305002301.95323-1-code@elbertmai.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'Documentation/ABI')
| -rw-r--r-- | Documentation/ABI/testing/sysfs-bus-usb | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-bus-usb b/Documentation/ABI/testing/sysfs-bus-usb index 2b7108e219775..af9b653422f16 100644 --- a/Documentation/ABI/testing/sysfs-bus-usb +++ b/Documentation/ABI/testing/sysfs-bus-usb @@ -442,6 +442,16 @@ What: /sys/bus/usb/devices/usbX/descriptors Description: Contains the interface descriptors, in binary. +What: /sys/bus/usb/devices/usbX/bos_descriptors +Date: March 2024 +Contact: Elbert Mai <code@elbertmai.com> +Description: + Binary file containing the cached binary device object store (BOS) + of the device. This consists of the BOS descriptor followed by the + set of device capability descriptors. All descriptors read from + this file are in bus-endian format. Note that the kernel will not + request the BOS from a device if its bcdUSB is less than 0x0201. + What: /sys/bus/usb/devices/usbX/idProduct Description: Product ID, in hexadecimal. |