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usb: docs

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This commit is contained in:
Dario Nieuwenhuis
2023-01-31 22:27:19 +01:00
parent 4c19464548
commit ca10fe7135
17 changed files with 267 additions and 97 deletions
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116
embassy-usb-driver/src/lib.rs
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@ -1,6 +1,8 @@
#![no_std]
#![feature(async_fn_in_trait)]
#![allow(incomplete_features)]
#![doc = include_str!("../README.md")]
#![warn(missing_docs)]
/// Direction of USB traffic. Note that in the USB standard the direction is always indicated from
/// the perspective of the host, which is backward for devices, but the standard directions are used
@ -95,46 +97,65 @@ impl EndpointAddress {
}
}
/// Infomation for an endpoint.
#[derive(Copy, Clone, Eq, PartialEq, Debug)]
#[cfg_attr(feature = "defmt", derive(defmt::Format))]
pub struct EndpointInfo {
/// Endpoint's address.
pub addr: EndpointAddress,
/// Endpoint's type.
pub ep_type: EndpointType,
/// Max packet size, in bytes.
pub max_packet_size: u16,
pub interval: u8,
/// Polling interval, in milliseconds.
pub interval_ms: u8,
}
/// Driver for a specific USB peripheral. Implement this to add support for a new hardware
/// platform.
/// Main USB driver trait.
///
/// Implement this to add support for a new hardware platform.
pub trait Driver<'a> {
/// Type of the OUT endpoints for this driver.
type EndpointOut: EndpointOut + 'a;
/// Type of the IN endpoints for this driver.
type EndpointIn: EndpointIn + 'a;
/// Type of the control pipe for this driver.
type ControlPipe: ControlPipe + 'a;
/// Type for bus control for this driver.
type Bus: Bus + 'a;
/// Allocates an endpoint and specified endpoint parameters. This method is called by the device
/// and class implementations to allocate endpoints, and can only be called before
/// [`start`](Self::start) is called.
/// Allocates an OUT endpoint.
///
/// This method is called by the USB stack to allocate endpoints.
/// It can only be called before [`start`](Self::start) is called.
///
/// # Arguments
///
/// * `ep_addr` - A static endpoint address to allocate. If Some, the implementation should
/// attempt to return an endpoint with the specified address. If None, the implementation
/// should return the next available one.
/// * `ep_type` - the endpoint's type.
/// * `max_packet_size` - Maximum packet size in bytes.
/// * `interval` - Polling interval parameter for interrupt endpoints.
/// * `interval_ms` - Polling interval parameter for interrupt endpoints.
fn alloc_endpoint_out(
&mut self,
ep_type: EndpointType,
max_packet_size: u16,
interval: u8,
interval_ms: u8,
) -> Result<Self::EndpointOut, EndpointAllocError>;
/// Allocates an IN endpoint.
///
/// This method is called by the USB stack to allocate endpoints.
/// It can only be called before [`start`](Self::start) is called.
///
/// # Arguments
///
/// * `ep_type` - the endpoint's type.
/// * `max_packet_size` - Maximum packet size in bytes.
/// * `interval_ms` - Polling interval parameter for interrupt endpoints.
fn alloc_endpoint_in(
&mut self,
ep_type: EndpointType,
max_packet_size: u16,
interval: u8,
interval_ms: u8,
) -> Result<Self::EndpointIn, EndpointAllocError>;
/// Start operation of the USB device.
@ -146,35 +167,37 @@ pub trait Driver<'a> {
/// This consumes the `Driver` instance, so it's no longer possible to allocate more
/// endpoints.
fn start(self, control_max_packet_size: u16) -> (Self::Bus, Self::ControlPipe);
/// Indicates that `set_device_address` must be called before accepting the corresponding
/// control transfer, not after.
///
/// The default value for this constant is `false`, which corresponds to the USB 2.0 spec, 9.4.6
const QUIRK_SET_ADDRESS_BEFORE_STATUS: bool = false;
}
/// USB bus trait.
///
/// This trait provides methods that act on the whole bus. It is kept owned by
/// the main USB task, and used to manage the bus.
pub trait Bus {
/// Enables the USB peripheral. Soon after enabling the device will be reset, so
/// there is no need to perform a USB reset in this method.
/// Enable the USB peripheral.
async fn enable(&mut self);
/// Disables and powers down the USB peripheral.
/// Disable and powers down the USB peripheral.
async fn disable(&mut self);
/// Wait for a bus-related event.
///
/// This method should asynchronously wait for an event to happen, then
/// return it. See [`Event`] for the list of events this method should return.
async fn poll(&mut self) -> Event;
/// Enables or disables an endpoint.
/// Enable or disable an endpoint.
fn endpoint_set_enabled(&mut self, ep_addr: EndpointAddress, enabled: bool);
/// Sets or clears the STALL condition for an endpoint. If the endpoint is an OUT endpoint, it
/// should be prepared to receive data again. Only used during control transfers.
/// Set or clear the STALL condition for an endpoint.
///
/// If the endpoint is an OUT endpoint, it should be prepared to receive data again.
fn endpoint_set_stalled(&mut self, ep_addr: EndpointAddress, stalled: bool);
/// Gets whether the STALL condition is set for an endpoint. Only used during control transfers.
/// Get whether the STALL condition is set for an endpoint.
fn endpoint_is_stalled(&mut self, ep_addr: EndpointAddress) -> bool;
/// Simulates a disconnect from the USB bus, causing the host to reset and re-enumerate the
/// Simulate a disconnect from the USB bus, causing the host to reset and re-enumerate the
/// device.
///
/// The default implementation just returns `Unsupported`.
@ -187,7 +210,7 @@ pub trait Bus {
Err(Unsupported)
}
/// Initiates a remote wakeup of the host by the device.
/// Initiate a remote wakeup of the host by the device.
///
/// # Errors
///
@ -196,25 +219,27 @@ pub trait Bus {
async fn remote_wakeup(&mut self) -> Result<(), Unsupported>;
}
/// Endpoint trait, common for OUT and IN.
pub trait Endpoint {
/// Get the endpoint address
fn info(&self) -> &EndpointInfo;
/// Waits for the endpoint to be enabled.
/// Wait for the endpoint to be enabled.
async fn wait_enabled(&mut self);
}
/// OUT Endpoint trait.
pub trait EndpointOut: Endpoint {
/// Reads a single packet of data from the endpoint, and returns the actual length of
/// Read a single packet of data from the endpoint, and return the actual length of
/// the packet.
///
/// This should also clear any NAK flags and prepare the endpoint to receive the next packet.
async fn read(&mut self, buf: &mut [u8]) -> Result<usize, EndpointError>;
}
/// Trait for USB control pipe.
/// USB control pipe trait.
///
/// The USB control pipe owns both OUT ep 0 and IN ep 0 in a single
/// The USB control pipe owns both OUT endpoint 0 and IN endpoint 0 in a single
/// unit, and manages them together to implement the control pipe state machine.
///
/// The reason this is a separate trait instead of using EndpointOut/EndpointIn is that
@ -232,6 +257,14 @@ pub trait EndpointOut: Endpoint {
/// accept() or reject()
/// ```
///
/// - control out for setting the device address:
///
/// ```not_rust
/// setup()
/// (...processing...)
/// accept_set_address(addr) or reject()
/// ```
///
/// - control out with len != 0:
///
/// ```not_rust
@ -280,26 +313,26 @@ pub trait ControlPipe {
/// Maximum packet size for the control pipe
fn max_packet_size(&self) -> usize;
/// Reads a single setup packet from the endpoint.
/// Read a single setup packet from the endpoint.
async fn setup(&mut self) -> [u8; 8];
/// Reads a DATA OUT packet into `buf` in response to a control write request.
/// Read a DATA OUT packet into `buf` in response to a control write request.
///
/// Must be called after `setup()` for requests with `direction` of `Out`
/// and `length` greater than zero.
async fn data_out(&mut self, buf: &mut [u8], first: bool, last: bool) -> Result<usize, EndpointError>;
/// Sends a DATA IN packet with `data` in response to a control read request.
/// Send a DATA IN packet with `data` in response to a control read request.
///
/// If `last_packet` is true, the STATUS packet will be ACKed following the transfer of `data`.
async fn data_in(&mut self, data: &[u8], first: bool, last: bool) -> Result<(), EndpointError>;
/// Accepts a control request.
/// Accept a control request.
///
/// Causes the STATUS packet for the current request to be ACKed.
async fn accept(&mut self);
/// Rejects a control request.
/// Reject a control request.
///
/// Sets a STALL condition on the pipe to indicate an error.
async fn reject(&mut self);
@ -311,8 +344,9 @@ pub trait ControlPipe {
async fn accept_set_address(&mut self, addr: u8);
}
/// IN Endpoint trait.
pub trait EndpointIn: Endpoint {
/// Writes a single packet of data to the endpoint.
/// Write a single packet of data to the endpoint.
async fn write(&mut self, buf: &[u8]) -> Result<(), EndpointError>;
}
@ -338,18 +372,22 @@ pub enum Event {
PowerRemoved,
}
/// Allocating an endpoint failed.
///
/// This can be due to running out of endpoints, or out of endpoint memory,
/// or because the hardware doesn't support the requested combination of features.
#[derive(Copy, Clone, Eq, PartialEq, Debug)]
#[cfg_attr(feature = "defmt", derive(defmt::Format))]
pub struct EndpointAllocError;
/// Operation is unsupported by the driver.
#[derive(Copy, Clone, Eq, PartialEq, Debug)]
#[cfg_attr(feature = "defmt", derive(defmt::Format))]
/// Operation is unsupported by the driver.
pub struct Unsupported;
/// Errors returned by [`EndpointIn::write`] and [`EndpointOut::read`]
#[derive(Copy, Clone, Eq, PartialEq, Debug)]
#[cfg_attr(feature = "defmt", derive(defmt::Format))]
/// Errors returned by [`EndpointIn::write`] and [`EndpointOut::read`]
pub enum EndpointError {
/// Either the packet to be written is too long to fit in the transmission
/// buffer or the received packet is too long to fit in `buf`.