get-descriptor-device.rs: add SET_ADDRESS handling; comments to solution

advanced/common/usb/src/get-descriptor-device.rs

@@ -5,9 +5,11 @@
 #![deny(warnings)]
 #![no_std]
 
-#[cfg(TODO)]
 use core::num::NonZeroU8;
 
+/// Device address assigned by the host; will be in the range 1..=127
+pub type Address = NonZeroU8;
+
 /// Standard USB request
 #[derive(Clone, Copy, Debug, PartialEq)]
 pub enum Request {
@@ -22,10 +24,9 @@ pub enum Request {
 
     /// SET_ADDRESS
     // see section 9.4.6 of the USB specification
-    #[cfg(TODO)]
     SetAddress {
         /// New device address, in the range `1..=127`
-        address: Option<NonZeroU8>,
+        address: Option<Address>,
     },
 
     /// SET_CONFIGURATION
@@ -50,17 +51,24 @@ impl Request {
         windex: u16,
         wlength: u16,
     ) -> Result<Self, ()> {
-        // see table 9-4
+        // see table 9-4 (USB specification)
+        const SET_ADDRESS: u8 = 5;
         const GET_DESCRIPTOR: u8 = 6;
 
+
         if bmrequesttype == 0b10000000 && brequest == GET_DESCRIPTOR {
             // see table 9-5
             const DEVICE: u8 = 1;
 
+            // 1. get descriptor type and descriptor index from wValue
             let desc_ty = (wvalue >> 8) as u8;
             let desc_index = wvalue as u8;
             let langid = windex;
 
+            // 2. confirm that the descriptor
+            //    - is of type DEVICE and
+            //    - has descriptor index 0 (i.e. it is the first implemented descriptor for this type) and
+            //    - has wIndex 0 (i.e. no language ID since it's not a string descriptor)
             if desc_ty == DEVICE && desc_index == 0 && langid == 0 {
                 Ok(Request::GetDescriptor {
                     descriptor: Descriptor::Device,
@@ -69,6 +77,18 @@ impl Request {
             } else {
                 Err(())
             }
+        } else if bmrequesttype == 0b00000000 && brequest == SET_ADDRESS {
+            // Set the device address for all future accesses.
+            // (Needed to successfully init when conected to Apple devices)
+            // Section 9.4.6 Set Address of the USB specification explains which values for wvalue,
+            // windex and wlength are valid.
+            if wvalue < 128 && windex == 0 && wlength == 0 {
+                Ok(Request::SetAddress {
+                    address: NonZeroU8::new(wvalue as u8),
+                })
+            } else {
+                Err(())
+            }
         } else {
             Err(())
         }
@@ -92,7 +112,6 @@ pub enum Descriptor {
 
 #[cfg(test)]
 mod tests {
-    #[cfg(TODO)]
     use core::num::NonZeroU8;
 
     use crate::{Descriptor, Request};
@@ -117,24 +136,6 @@ mod tests {
         //                                                 ^^^^
     }
 
-    #[cfg(TODO)]
-    #[test]
-    fn get_descriptor_configuration() {
-        // OK: GET_DESCRIPTOR Configuration 0 [length=9]
-        assert_eq!(
-            Request::parse(0b1000_0000, 0x06, 0x02_00, 0, 9),
-            Ok(Request::GetDescriptor {
-                descriptor: Descriptor::Configuration { index: 0 },
-                length: 9
-            })
-        );
-
-        // has language ID but shouldn't
-        assert!(Request::parse(0b1000_0000, 0x06, 0x02_00, 1033, 9).is_err());
-        //                                                 ^^^^
-    }
-
-    #[cfg(TODO)]
     #[test]
     fn set_address() {
         // OK: SET_ADDRESS 16
@@ -164,6 +165,23 @@ mod tests {
         //                                                    ^
     }
 
+    #[cfg(TODO)]
+    #[test]
+    fn get_descriptor_configuration() {
+        // OK: GET_DESCRIPTOR Configuration 0 [length=9]
+        assert_eq!(
+            Request::parse(0b1000_0000, 0x06, 0x02_00, 0, 9),
+            Ok(Request::GetDescriptor {
+                descriptor: Descriptor::Configuration { index: 0 },
+                length: 9
+            })
+        );
+
+        // has language ID but shouldn't
+        assert!(Request::parse(0b1000_0000, 0x06, 0x02_00, 1033, 9).is_err());
+        //                                                 ^^^^
+    }
+
     #[cfg(TODO)]
     #[test]
     fn set_configuration() {