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|
//! This crate defines a set of traits for use on the host side of the
//! USB.
//!
//! The `USBHost` defines the Host Controller Interface that can be
//! used by the `Driver` interface.
//!
//! The `Driver` interface defines the set of functions necessary to
//! use devices plugged into the host.
#![no_std]
pub mod descriptor;
pub mod setup;
pub use descriptor::*;
pub use setup::*;
/// Errors that can be generated when attempting to do a USB transfer.
#[derive(Debug)]
pub enum TransferError {
/// An error that may be retried.
Retry(&'static str),
/// A permanent error.
Permanent(&'static str),
}
/// Trait for host controller interface.
pub trait USBHost {
/// Issue a control transfer with an optional data stage to
/// `ep`. The data stage direction is determined by the direction
/// of `bm_request_type`.
///
/// On success, the amount of data transferred into `buf` is
/// returned.
fn control_transfer(
&mut self,
ep: &mut dyn Endpoint,
bm_request_type: RequestType,
b_request: RequestCode,
w_value: WValue,
w_index: u16,
buf: Option<&mut [u8]>,
) -> Result<usize, TransferError>;
/// Issue a transfer from `ep` to the host.
///
/// On success, the amount of data transferred into `buf` is
/// returned.
fn in_transfer(
&mut self,
ep: &mut dyn Endpoint,
buf: &mut [u8],
) -> Result<usize, TransferError>;
/// Issue a transfer from the host to `ep`.
///
/// On success, the amount of data transferred from `buf` is
/// returned. This should always be equal to `buf.len()`.
fn out_transfer(&mut self, ep: &mut dyn Endpoint, buf: &[u8]) -> Result<usize, TransferError>;
}
/// The type of transfer to use when talking to USB devices.
///
/// cf §9.6.6 of USB 2.0
#[derive(Copy, Clone, Debug, PartialEq)]
pub enum TransferType {
Control = 0,
Isochronous = 1,
Bulk = 2,
Interrupt = 3,
}
/// The direction of the transfer with the USB device.
///
/// cf §9.6.6 of USB 2.0
#[derive(Copy, Clone, Debug, PartialEq)]
pub enum Direction {
Out,
In,
}
/// `Endpoint` defines the USB endpoint for various transfers.
pub trait Endpoint {
/// Address of the device owning this endpoint. Must be between 0
/// and 127.
fn address(&self) -> u8;
/// Endpoint number, irrespective of direction. (e.g., for both
/// endpoint addresses, `0x81` and `0x01`, this function would
/// return `0x01`).
fn endpoint_num(&self) -> u8;
/// The type of transfer this endpoint uses.
fn transfer_type(&self) -> TransferType;
/// The direction of transfer this endpoint accepts.
fn direction(&self) -> Direction;
/// The maximum packet size for this endpoint.
fn max_packet_size(&self) -> u16;
/// The data toggle sequence bit for the next transfer from the
/// device to the host.
fn in_toggle(&self) -> bool;
/// The `USBHost` will, when required, update the data toggle
/// sequence bit for the next device to host transfer.
fn set_in_toggle(&mut self, toggle: bool);
/// The data toggle sequence bit for the next transfer from the
/// host to the device.
fn out_toggle(&self) -> bool;
/// The `USBHost` will, when required, update the data toggle
/// sequence bit for the next host to device transfer.
fn set_out_toggle(&mut self, toggle: bool);
}
/// Types of errors that can be returned from a `Driver`.
#[derive(Copy, Clone, Debug)]
pub enum DriverError {
/// An error that may be retried.
Retry(u8, &'static str),
/// A permanent error.
Permanent(u8, &'static str),
}
/// Trait for drivers on the USB host.
pub trait Driver: core::fmt::Debug {
/// Does this driver want `device`?
///
/// Answering `true` to this not necessarily mean the driver will
/// get `device`.
fn want_device(&self, device: &DeviceDescriptor) -> bool;
/// Add `device` with address `address` to the driver's registry,
/// if necessary.
fn add_device(&mut self, device: DeviceDescriptor, address: u8) -> Result<(), DriverError>;
/// Remove the device at address `address` from the driver's
/// registry, if necessary.
fn remove_device(&mut self, address: u8);
/// Called regularly by the USB host to allow the driver to do any
/// work necessary on its registered devices.
///
/// `millis` is the current time, in milliseconds from some
/// arbitrary starting point. It should be expected that after a
/// long enough run-time, this value will wrap.
///
/// `usbhost` may be used for communication with the USB when
/// required.
fn tick(&mut self, millis: usize, usbhost: &mut dyn USBHost) -> Result<(), DriverError>;
}
|
