usb: unify ControlHandler+DeviceStateHandler, route all control requests to all handlers.

- Allows classes to handle vendor requests.
- Allows classes to use a single handler for multiple interfaces.
- Allows classes to access the other events (previously only `reset` was available).

embassy-usb/src/builder.rs

@@ -1,12 +1,12 @@
 use heapless::Vec;
 
-use crate::control::ControlHandler;
+use crate::config::*;
 use crate::descriptor::{BosWriter, DescriptorWriter};
 use crate::driver::{Driver, Endpoint, EndpointType};
 #[cfg(feature = "msos-descriptor")]
 use crate::msos::{DeviceLevelDescriptor, FunctionLevelDescriptor, MsOsDescriptorWriter};
 use crate::types::*;
-use crate::{DeviceStateHandler, Interface, UsbDevice, MAX_INTERFACE_COUNT, STRING_INDEX_CUSTOM_START};
+use crate::{Handler, Interface, UsbDevice, MAX_INTERFACE_COUNT, STRING_INDEX_CUSTOM_START};
 
 #[derive(Debug, Copy, Clone)]
 #[cfg_attr(feature = "defmt", derive(defmt::Format))]
@@ -122,8 +122,8 @@ impl<'a> Config<'a> {
 /// [`UsbDevice`] builder.
 pub struct Builder<'d, D: Driver<'d>> {
     config: Config<'d>,
-    handler: Option<&'d dyn DeviceStateHandler>,
-    interfaces: Vec<Interface<'d>, MAX_INTERFACE_COUNT>,
+    handlers: Vec<&'d mut dyn Handler, MAX_HANDLER_COUNT>,
+    interfaces: Vec<Interface, MAX_INTERFACE_COUNT>,
     control_buf: &'d mut [u8],
 
     driver: D,
@@ -151,7 +151,6 @@ impl<'d, D: Driver<'d>> Builder<'d, D> {
         bos_descriptor_buf: &'d mut [u8],
         #[cfg(feature = "msos-descriptor")] msos_descriptor_buf: &'d mut [u8],
         control_buf: &'d mut [u8],
-        handler: Option<&'d dyn DeviceStateHandler>,
     ) -> Self {
         // Magic values specified in USB-IF ECN on IADs.
         if config.composite_with_iads
@@ -179,9 +178,9 @@ impl<'d, D: Driver<'d>> Builder<'d, D> {
 
         Builder {
             driver,
-            handler,
             config,
             interfaces: Vec::new(),
+            handlers: Vec::new(),
             control_buf,
             next_string_index: STRING_INDEX_CUSTOM_START,
 
@@ -205,7 +204,7 @@ impl<'d, D: Driver<'d>> Builder<'d, D> {
         UsbDevice::build(
             self.driver,
             self.config,
-            self.handler,
+            self.handlers,
             self.device_descriptor.into_buf(),
             self.config_descriptor.into_buf(),
             self.bos_descriptor.writer.into_buf(),
@@ -248,6 +247,26 @@ impl<'d, D: Driver<'d>> Builder<'d, D> {
         }
     }
 
+    /// Add a Handler.
+    ///
+    /// The Handler is called on some USB bus events, and to handle all control requests not already
+    /// handled by the USB stack.
+    pub fn handler(&mut self, handler: &'d mut dyn Handler) {
+        if self.handlers.push(handler).is_err() {
+            panic!(
+                "embassy-usb: handler list full. Increase the `max_handler_count` compile-time setting. Current value: {}",
+                MAX_HANDLER_COUNT
+            )
+        }
+    }
+
+    /// Allocates a new string index.
+    pub fn string(&mut self) -> StringIndex {
+        let index = self.next_string_index;
+        self.next_string_index += 1;
+        StringIndex::new(index)
+    }
+
     #[cfg(feature = "msos-descriptor")]
     /// Add an MS OS 2.0 Descriptor Set.
     ///
@@ -301,10 +320,8 @@ impl<'a, 'd, D: Driver<'d>> FunctionBuilder<'a, 'd, D> {
 
         let number = self.builder.interfaces.len() as _;
         let iface = Interface {
-            handler: None,
             current_alt_setting: 0,
             num_alt_settings: 0,
-            num_strings: 0,
         };
 
         if self.builder.interfaces.push(iface).is_err() {
@@ -350,17 +367,9 @@ impl<'a, 'd, D: Driver<'d>> InterfaceBuilder<'a, 'd, D> {
         self.interface_number
     }
 
-    pub fn handler(&mut self, handler: &'d mut dyn ControlHandler) {
-        self.builder.interfaces[self.interface_number.0 as usize].handler = Some(handler);
-    }
-
     /// Allocates a new string index.
     pub fn string(&mut self) -> StringIndex {
-        let index = self.builder.next_string_index;
-        self.builder.next_string_index += 1;
-        self.builder.interfaces[self.interface_number.0 as usize].num_strings += 1;
-
-        StringIndex::new(index)
+        self.builder.string()
     }
 
     /// Add an alternate setting to the interface and write its descriptor.