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Right now my goal is just to respond to a setup request with the right sequence of descriptors to appear to be a serial device. For the moment I've just removed HID support to avoid figuring out how to support HID _or_ CDC. Signed-off-by: Nic Cope <nicc@rk0n.org>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,124 @@ | ||
| // USB CDC | ||
| // | ||
| // This is just enough implementation to allow us to act as a USB serial device. | ||
| // https://cscott.net/usb_dev/data/devclass/usbcdc11.pdf | ||
|
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| const std = @import("std"); | ||
|
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| pub const DescType = enum(u8) { | ||
| /// Class-specific descriptor | ||
| ClassSpecific = 0x24, | ||
|
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| pub fn from_u16(v: u16) ?@This() { | ||
| return switch (v) { | ||
| 0x24 => @This().ClassSpecific, | ||
| else => null, | ||
| }; | ||
| } | ||
| }; | ||
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| pub const DescSubType = enum(u8) { | ||
| Header = 0x00, | ||
| CallManagement = 0x01, | ||
| ACM = 0x02, | ||
| Union = 0x06, | ||
|
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| pub fn from_u16(v: u16) ?@This() { | ||
| return switch (v) { | ||
| 0x00 => @This().Header, | ||
| 0x01 => @This().CallManagement, | ||
| 0x02 => @This().ACM, | ||
| 0x06 => @This().Union, | ||
| }; | ||
| } | ||
| }; | ||
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| pub const ClassSpecificCDCHeader = extern struct { | ||
| // Length of this structure, must be 5. | ||
| length: u8, | ||
| // Type of this descriptor, must be `ClassSpecific`. | ||
| descriptor_type: DescType, | ||
| // Subtype of this descriptor, must be `Header`. | ||
| descriptor_subtype: DescSubType, | ||
| // USB Class Definitions for Communication Devices Specification release | ||
| // number in binary-coded decimal. Typically 0x01_10. | ||
| bcd_cdc: u16, | ||
|
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| pub fn serialize(self: *const @This()) [8]u8 { | ||
| var out: [8]u8 = undefined; | ||
| out[0] = 5; // length | ||
| out[1] = @intFromEnum(self.descriptor_type); | ||
| out[2] = @intFromEnum(self.descriptor_subtype); | ||
| out[3] = @intCast(self.bcd_cdc & 0xff); | ||
| out[4] = @intCast((self.bcd_cdc >> 8) & 0xff); | ||
| return out; | ||
| } | ||
| }; | ||
|
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| pub const ClassSpecificCDCCallManagement = extern struct { | ||
| // Length of this structure, must be 5. | ||
| length: u8, | ||
| // Type of this descriptor, must be `ClassSpecific`. | ||
| descriptor_type: DescType, | ||
| // Subtype of this descriptor, must be `CallManagement`. | ||
| descriptor_subtype: DescSubType, | ||
| // Capabilities. Should be 0x00 for use as a serial device. | ||
| capabilities: u8, | ||
| // Data interface number. | ||
| data_interface: u8, | ||
|
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| pub fn serialize(self: *const @This()) [8]u8 { | ||
| var out: [8]u8 = undefined; | ||
| out[0] = 5; // length | ||
| out[1] = @intFromEnum(self.descriptor_type); | ||
| out[2] = @intFromEnum(self.descriptor_subtype); | ||
| out[3] = self.capabilities; | ||
| out[4] = self.data_interface; | ||
| return out; | ||
| } | ||
| }; | ||
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| pub const ClassSpecificCDCACM = extern struct { | ||
| // Length of this structure, must be 4. | ||
| length: u8, | ||
| // Type of this descriptor, must be `ClassSpecific`. | ||
| descriptor_type: DescType, | ||
| // Subtype of this descriptor, must be `ACM`. | ||
| descriptor_subtype: DescSubType, | ||
| // Capabilities. Should be 0x02 for use as a serial device. | ||
| capabilities: u8, | ||
|
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||
| pub fn serialize(self: *const @This()) [8]u8 { | ||
| var out: [8]u8 = undefined; | ||
| out[0] = 4; // length | ||
| out[1] = @intFromEnum(self.descriptor_type); | ||
| out[2] = @intFromEnum(self.descriptor_subtype); | ||
| out[3] = self.capabilities; | ||
| return out; | ||
| } | ||
| }; | ||
|
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| pub const ClassSpecificCDCUnion = extern struct { | ||
| // Length of this structure, must be 5. | ||
| length: u8, | ||
| // Type of this descriptor, must be `ClassSpecific`. | ||
| descriptor_type: DescType, | ||
| // Subtype of this descriptor, must be `Union`. | ||
| descriptor_subtype: DescSubType, | ||
| // The interface number of the communication or data class interface | ||
| // designated as the master or controlling interface for the union. | ||
| master_interface: u8, | ||
| // The interface number of the first slave or associated interface in the | ||
| // union. | ||
| slave_interface_0: u8, | ||
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| pub fn serialize(self: *const @This()) [8]u8 { | ||
| var out: [8]u8 = undefined; | ||
| out[0] = 5; // length | ||
| out[1] = @intFromEnum(self.descriptor_type); | ||
| out[2] = @intFromEnum(self.descriptor_subtype); | ||
| out[3] = self.master_interface; | ||
| out[4] = self.slave_interface_0; | ||
| return out; | ||
| } | ||
| }; |