usb: unify handling of length parameters

The length parameters in USB packets are strict and the existing implementation does already hardcode the length within the serialize functions. Therefore the user should not provide these lengths during creation time. In order to make this more verbose use defaults values within the structs and reference these defaults values within the serialization functions. It's not possible to remove these fields completly as this fields are used within deserialization from the hardware itself. Signed-off-by: Tobias Kohlbau <[email protected]>
ZigEmbeddedGroup · Feb 25, 2024 · 64dc121 · 64dc121
1 parent 245401a
commit 64dc121
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Showing 5 changed files with 10 additions and 22 deletions.
diff --git a/board-support/raspberrypi-rp2040/src/hal/usb.zig b/board-support/raspberrypi-rp2040/src/hal/usb.zig
@@ -42,7 +42,6 @@ pub const utf8ToUtf16Le = usb.utf8Toutf16Le;
 
 pub var EP0_OUT_CFG: usb.EndpointConfiguration = .{
     .descriptor = &usb.EndpointDescriptor{
-        .length = @as(u8, @intCast(@sizeOf(usb.EndpointDescriptor))),
         .descriptor_type = usb.DescType.Endpoint,
         .endpoint_address = usb.EP0_OUT_ADDR,
         .attributes = @intFromEnum(usb.TransferType.Control),
@@ -57,7 +56,6 @@ pub var EP0_OUT_CFG: usb.EndpointConfiguration = .{
 
 pub var EP0_IN_CFG: usb.EndpointConfiguration = .{
     .descriptor = &usb.EndpointDescriptor{
-        .length = @as(u8, @intCast(@sizeOf(usb.EndpointDescriptor))),
         .descriptor_type = usb.DescType.Endpoint,
         .endpoint_address = usb.EP0_IN_ADDR,
         .attributes = @intFromEnum(usb.TransferType.Control),

diff --git a/core/src/core/usb.zig b/core/src/core/usb.zig
@@ -513,7 +513,7 @@ pub const Dir = enum(u8) {
 /// Describes an endpoint within an interface
 pub const EndpointDescriptor = extern struct {
     /// Length of this struct, must be 7.
-    length: u8,
+    length: u8 = 7,
     /// Type of this descriptor, must be `Endpoint`.
     descriptor_type: DescType,
     /// Address of this endpoint, where the bottom 4 bits give the endpoint
@@ -530,7 +530,7 @@ pub const EndpointDescriptor = extern struct {
 
     pub fn serialize(self: *const @This()) [7]u8 {
         var out: [7]u8 = undefined;
-        out[0] = 7; // length
+        out[0] = self.length;
         out[1] = @intFromEnum(self.descriptor_type);
         out[2] = self.endpoint_address;
         out[3] = self.attributes;
@@ -544,7 +544,7 @@ pub const EndpointDescriptor = extern struct {
 /// Description of an interface within a configuration.
 pub const InterfaceDescriptor = extern struct {
     /// Length of this structure, must be 9.
-    length: u8,
+    length: u8 = 9,
     /// Type of this descriptor, must be `Interface`.
     descriptor_type: DescType,
     /// ID of this interface.
@@ -566,7 +566,7 @@ pub const InterfaceDescriptor = extern struct {
 
     pub fn serialize(self: *const @This()) [9]u8 {
         var out: [9]u8 = undefined;
-        out[0] = 9; // length
+        out[0] = self.length;
         out[1] = @intFromEnum(self.descriptor_type);
         out[2] = self.interface_number;
         out[3] = self.alternate_setting;
@@ -582,7 +582,7 @@ pub const InterfaceDescriptor = extern struct {
 /// Description of a single available device configuration.
 pub const ConfigurationDescriptor = extern struct {
     /// Length of this structure, must be 9.
-    length: u8,
+    length: u8 = 9,
     /// Type of this descriptor, must be `Config`.
     descriptor_type: DescType,
     /// Total length of all descriptors in this configuration, concatenated.
@@ -610,7 +610,7 @@ pub const ConfigurationDescriptor = extern struct {
 
     pub fn serialize(self: *const @This()) [9]u8 {
         var out: [9]u8 = undefined;
-        out[0] = 9; // length
+        out[0] = self.length;
         out[1] = @intFromEnum(self.descriptor_type);
         out[2] = @intCast(self.total_length & 0xff);
         out[3] = @intCast((self.total_length >> 8) & 0xff);
@@ -627,7 +627,7 @@ pub const ConfigurationDescriptor = extern struct {
 /// typically the first thing the host asks for.
 pub const DeviceDescriptor = extern struct {
     /// Length of this structure, must be 18.
-    length: u8,
+    length: u8 = 18,
     /// Type of this descriptor, must be `Device`.
     descriptor_type: DescType,
     /// Version of the device descriptor / USB protocol, in binary-coded
@@ -658,7 +658,7 @@ pub const DeviceDescriptor = extern struct {
 
     pub fn serialize(self: *const @This()) [18]u8 {
         var out: [18]u8 = undefined;
-        out[0] = 18; // length
+        out[0] = self.length;
         out[1] = @intFromEnum(self.descriptor_type);
         out[2] = @intCast(self.bcd_usb & 0xff);
         out[3] = @intCast((self.bcd_usb >> 8) & 0xff);
@@ -705,7 +705,7 @@ pub const DeviceQualifierDescriptor = extern struct {
 
     pub fn serialize(self: *const @This()) [10]u8 {
         var out: [10]u8 = undefined;
-        out[0] = 10; // length
+        out[0] = self.length;
         out[1] = @intFromEnum(self.descriptor_type);
         out[2] = @intCast(self.bcd_usb & 0xff);
         out[3] = @intCast((self.bcd_usb >> 8) & 0xff);

diff --git a/core/src/core/usb/hid.zig b/core/src/core/usb/hid.zig
@@ -103,7 +103,7 @@ pub const HidDescriptor = extern struct {
 
     pub fn serialize(self: *const @This()) [9]u8 {
         var out: [9]u8 = undefined;
-        out[0] = 9; // length
+        out[0] = self.length;
         out[1] = @intFromEnum(self.descriptor_type);
         out[2] = @intCast(self.bcd_hid & 0xff);
         out[3] = @intCast((self.bcd_hid >> 8) & 0xff);

diff --git a/examples/raspberrypi-rp2040/src/usb_device.zig b/examples/raspberrypi-rp2040/src/usb_device.zig
@@ -38,7 +38,6 @@ fn ep1_out_callback(dc: *usb.DeviceConfiguration, data: []const u8) void {
 // add your own endpoints to...
 pub var EP1_OUT_CFG: usb.EndpointConfiguration = .{
     .descriptor = &usb.EndpointDescriptor{
-        .length = @as(u8, @intCast(@sizeOf(usb.EndpointDescriptor))),
         .descriptor_type = usb.DescType.Endpoint,
         .endpoint_address = usb.Dir.Out.endpoint(1),
         .attributes = @intFromEnum(usb.TransferType.Bulk),
@@ -55,7 +54,6 @@ pub var EP1_OUT_CFG: usb.EndpointConfiguration = .{
 
 pub var EP1_IN_CFG: usb.EndpointConfiguration = .{
     .descriptor = &usb.EndpointDescriptor{
-        .length = @as(u8, @intCast(@sizeOf(usb.EndpointDescriptor))),
         .descriptor_type = usb.DescType.Endpoint,
         .endpoint_address = usb.Dir.In.endpoint(1),
         .attributes = @intFromEnum(usb.TransferType.Bulk),
@@ -73,7 +71,6 @@ pub var EP1_IN_CFG: usb.EndpointConfiguration = .{
 // This is our device configuration
 pub var DEVICE_CONFIGURATION: usb.DeviceConfiguration = .{
     .device_descriptor = &.{
-        .length = @as(u8, @intCast(@sizeOf(usb.DeviceDescriptor))),
         .descriptor_type = usb.DescType.Device,
         .bcd_usb = 0x0110,
         .device_class = 0,
@@ -89,7 +86,6 @@ pub var DEVICE_CONFIGURATION: usb.DeviceConfiguration = .{
         .num_configurations = 1,
     },
     .interface_descriptor = &.{
-        .length = @as(u8, @intCast(@sizeOf(usb.InterfaceDescriptor))),
         .descriptor_type = usb.DescType.Interface,
         .interface_number = 0,
         .alternate_setting = 0,
@@ -101,7 +97,6 @@ pub var DEVICE_CONFIGURATION: usb.DeviceConfiguration = .{
         .interface_s = 0,
     },
     .config_descriptor = &.{
-        .length = @as(u8, @intCast(@sizeOf(usb.ConfigurationDescriptor))),
         .descriptor_type = usb.DescType.Config,
         .total_length = @as(u8, @intCast(@sizeOf(usb.ConfigurationDescriptor) + @sizeOf(usb.InterfaceDescriptor) + @sizeOf(usb.EndpointDescriptor) + @sizeOf(usb.EndpointDescriptor))),
         .num_interfaces = 1,

diff --git a/examples/raspberrypi-rp2040/src/usb_hid.zig b/examples/raspberrypi-rp2040/src/usb_hid.zig
@@ -38,7 +38,6 @@ fn ep1_out_callback(dc: *usb.DeviceConfiguration, data: []const u8) void {
 // add your own endpoints to...
 pub var EP1_OUT_CFG: usb.EndpointConfiguration = .{
     .descriptor = &usb.EndpointDescriptor{
-        .length = @as(u8, @intCast(@sizeOf(usb.EndpointDescriptor))),
         .descriptor_type = usb.DescType.Endpoint,
         .endpoint_address = usb.Dir.Out.endpoint(1),
         .attributes = @intFromEnum(usb.TransferType.Interrupt),
@@ -55,7 +54,6 @@ pub var EP1_OUT_CFG: usb.EndpointConfiguration = .{
 
 pub var EP1_IN_CFG: usb.EndpointConfiguration = .{
     .descriptor = &usb.EndpointDescriptor{
-        .length = @as(u8, @intCast(@sizeOf(usb.EndpointDescriptor))),
         .descriptor_type = usb.DescType.Endpoint,
         .endpoint_address = usb.Dir.In.endpoint(1),
         .attributes = @intFromEnum(usb.TransferType.Interrupt),
@@ -73,7 +71,6 @@ pub var EP1_IN_CFG: usb.EndpointConfiguration = .{
 // This is our device configuration
 pub var DEVICE_CONFIGURATION: usb.DeviceConfiguration = .{
     .device_descriptor = &.{
-        .length = @as(u8, @intCast(@sizeOf(usb.DeviceDescriptor))),
         .descriptor_type = usb.DescType.Device,
         .bcd_usb = 0x0200,
         .device_class = 0,
@@ -91,7 +88,6 @@ pub var DEVICE_CONFIGURATION: usb.DeviceConfiguration = .{
         .num_configurations = 1,
     },
     .interface_descriptor = &.{
-        .length = @as(u8, @intCast(@sizeOf(usb.InterfaceDescriptor))),
         .descriptor_type = usb.DescType.Interface,
         .interface_number = 0,
         .alternate_setting = 0,
@@ -103,7 +99,6 @@ pub var DEVICE_CONFIGURATION: usb.DeviceConfiguration = .{
         .interface_s = 0,
     },
     .config_descriptor = &.{
-        .length = @as(u8, @intCast(@sizeOf(usb.ConfigurationDescriptor))),
         .descriptor_type = usb.DescType.Config,
         .total_length = @as(u8, @intCast(@sizeOf(usb.ConfigurationDescriptor) + @sizeOf(usb.InterfaceDescriptor) + @sizeOf(usb.EndpointDescriptor) + @sizeOf(usb.EndpointDescriptor))),
         .num_interfaces = 1,