Merge pull request #3259 from HaoboGu/feat/usb_device_qualifier_desc

embassy-usb: add USB device qualifier descriptor

Author: lulf

embassy-usb/src/descriptor.rs

@@ -13,6 +13,8 @@ pub mod descriptor_type {
     pub const STRING: u8 = 3;
     pub const INTERFACE: u8 = 4;
     pub const ENDPOINT: u8 = 5;
+    pub const DEVICE_QUALIFIER: u8 = 6;
+    pub const OTHER_SPEED_CONFIGURATION: u8 = 7;
     pub const IAD: u8 = 11;
     pub const BOS: u8 = 15;
     pub const CAPABILITY: u8 = 16;
@@ -272,6 +274,25 @@ pub(crate) fn device_descriptor(config: &Config) -> [u8; 18] {
     ]
 }
 
+/// Create a new Device Qualifier Descriptor array.
+///
+/// All device qualifier descriptors are always 10 bytes, so there's no need for
+/// a variable-length buffer or DescriptorWriter.
+pub(crate) fn device_qualifier_descriptor(config: &Config) -> [u8; 10] {
+    [
+        10,   // bLength
+        0x06, // bDescriptorType
+        0x10,
+        0x02,                     // bcdUSB 2.1
+        config.device_class,      // bDeviceClass
+        config.device_sub_class,  // bDeviceSubClass
+        config.device_protocol,   // bDeviceProtocol
+        config.max_packet_size_0, // bMaxPacketSize0
+        1,                        // bNumConfigurations
+        0,                        // Reserved
+    ]
+}
+
 /// A writer for Binary Object Store descriptor.
 pub struct BosWriter<'a> {
     pub(crate) writer: DescriptorWriter<'a>,

embassy-usb/src/lib.rs

@@ -190,6 +190,7 @@ struct Inner<'d, D: Driver<'d>> {
 
     config: Config<'d>,
     device_descriptor: [u8; 18],
+    device_qualifier_descriptor: [u8; 10],
     config_descriptor: &'d [u8],
     bos_descriptor: &'d [u8],
     msos_descriptor: crate::msos::MsOsDescriptorSet<'d>,
@@ -225,6 +226,7 @@ impl<'d, D: Driver<'d>> UsbDevice<'d, D> {
         // This prevent further allocation by consuming the driver.
         let (bus, control) = driver.start(config.max_packet_size_0 as u16);
         let device_descriptor = descriptor::device_descriptor(&config);
+        let device_qualifier_descriptor = descriptor::device_qualifier_descriptor(&config);
 
         Self {
             control_buf,
@@ -233,6 +235,7 @@ impl<'d, D: Driver<'d>> UsbDevice<'d, D> {
                 bus,
                 config,
                 device_descriptor,
+                device_qualifier_descriptor,
                 config_descriptor,
                 bos_descriptor,
                 msos_descriptor,
@@ -764,6 +767,7 @@ impl<'d, D: Driver<'d>> Inner<'d, D> {
                     }
                 }
             }
+            descriptor_type::DEVICE_QUALIFIER => InResponse::Accepted(&self.device_qualifier_descriptor),
             _ => InResponse::Rejected,
         }
     }