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Initial import to v1a, does not compile

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This commit is contained in:
David Lenfesty 2022-04-21 17:07:46 -06:00 committed by Dario Nieuwenhuis
parent 2f43969dd4
commit f30e5d2d3f
5 changed files with 928 additions and 0 deletions
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1
embassy-stm32/src/eth/mod.rs
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@ -1,5 +1,6 @@
#![macro_use]
#[cfg_attr(eth_v1a, path = "v1a/mod.rs")]
#[cfg_attr(eth_v1c, path = "v1c/mod.rs")]
#[cfg_attr(eth_v2, path = "v2/mod.rs")]
#[cfg_attr(eth_v1, path = "v1.rs")]

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embassy-stm32/src/eth/v1a/descriptors.rs Normal file
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use crate::eth::_version::rx_desc::RDesRing;
use crate::eth::_version::tx_desc::TDesRing;
pub struct DescriptorRing<const T: usize, const R: usize> {
pub(crate) tx: TDesRing<T>,
pub(crate) rx: RDesRing<R>,
}
impl<const T: usize, const R: usize> DescriptorRing<T, R> {
pub const fn new() -> Self {
Self {
tx: TDesRing::new(),
rx: RDesRing::new(),
}
}
pub fn init(&mut self) {
self.tx.init();
self.rx.init();
}
}

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embassy-stm32/src/eth/v1a/mod.rs Normal file
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// The v1c ethernet driver was ported to embassy from the awesome stm32-eth project (https://github.com/stm32-rs/stm32-eth).
use core::marker::PhantomData;
use core::sync::atomic::{fence, Ordering};
use core::task::Waker;
use embassy::util::Unborrow;
use embassy::waitqueue::AtomicWaker;
use embassy_hal_common::peripheral::{PeripheralMutex, PeripheralState, StateStorage};
use embassy_hal_common::unborrow;
use embassy_net::{Device, DeviceCapabilities, LinkState, PacketBuf, MTU};
use crate::gpio::sealed::Pin as __GpioPin;
use crate::gpio::{sealed::AFType, AnyPin, Speed};
use crate::pac::{ETH, RCC, SYSCFG};
mod descriptors;
mod rx_desc;
mod tx_desc;
use super::*;
use descriptors::DescriptorRing;
use stm32_metapac::eth::vals::{
Apcs, Cr, Dm, DmaomrSr, Fes, Ftf, Ifg, MbProgress, Mw, Pbl, Rsf, St, Tsf,
};
pub struct State<'d, T: Instance, const TX: usize, const RX: usize>(
StateStorage<Inner<'d, T, TX, RX>>,
);
impl<'d, T: Instance, const TX: usize, const RX: usize> State<'d, T, TX, RX> {
pub fn new() -> Self {
Self(StateStorage::new())
}
}
pub struct Ethernet<'d, T: Instance, P: PHY, const TX: usize, const RX: usize> {
state: PeripheralMutex<'d, Inner<'d, T, TX, RX>>,
pins: [AnyPin; 9],
_phy: P,
clock_range: Cr,
phy_addr: u8,
mac_addr: [u8; 6],
}
macro_rules! config_pins {
($($pin:ident),*) => {
// NOTE(unsafe) Exclusive access to the registers
critical_section::with(|_| {
$(
$pin.set_as_af($pin.af_num(), AFType::OutputPushPull);
$pin.set_speed(Speed::VeryHigh);
)*
})
};
}
impl<'d, T: Instance, P: PHY, const TX: usize, const RX: usize> Ethernet<'d, T, P, TX, RX> {
/// safety: the returned instance is not leak-safe
pub unsafe fn new(
state: &'d mut State<'d, T, TX, RX>,
peri: impl Unborrow<Target = T> + 'd,
interrupt: impl Unborrow<Target = crate::interrupt::ETH> + 'd,
ref_clk: impl Unborrow<Target = impl RefClkPin<T>> + 'd,
mdio: impl Unborrow<Target = impl MDIOPin<T>> + 'd,
mdc: impl Unborrow<Target = impl MDCPin<T>> + 'd,
crs: impl Unborrow<Target = impl CRSPin<T>> + 'd,
rx_d0: impl Unborrow<Target = impl RXD0Pin<T>> + 'd,
rx_d1: impl Unborrow<Target = impl RXD1Pin<T>> + 'd,
tx_d0: impl Unborrow<Target = impl TXD0Pin<T>> + 'd,
tx_d1: impl Unborrow<Target = impl TXD1Pin<T>> + 'd,
tx_en: impl Unborrow<Target = impl TXEnPin<T>> + 'd,
phy: P,
mac_addr: [u8; 6],
phy_addr: u8,
) -> Self {
unborrow!(interrupt, ref_clk, mdio, mdc, crs, rx_d0, rx_d1, tx_d0, tx_d1, tx_en);
// Enable the necessary Clocks
// NOTE(unsafe) We have exclusive access to the registers
critical_section::with(|_| {
RCC.apb2enr().modify(|w| w.set_syscfgen(true));
RCC.ahb1enr().modify(|w| {
w.set_ethen(true);
w.set_ethtxen(true);
w.set_ethrxen(true);
});
// RMII (Reduced Media Independent Interface)
SYSCFG.pmc().modify(|w| w.set_mii_rmii_sel(true));
});
config_pins!(ref_clk, mdio, mdc, crs, rx_d0, rx_d1, tx_d0, tx_d1, tx_en);
// NOTE(unsafe) We are ourselves not leak-safe.
let state = PeripheralMutex::new_unchecked(interrupt, &mut state.0, || Inner::new(peri));
// NOTE(unsafe) We have exclusive access to the registers
let dma = ETH.ethernet_dma();
let mac = ETH.ethernet_mac();
// Reset and wait
dma.dmabmr().modify(|w| w.set_sr(true));
while dma.dmabmr().read().sr() {}
mac.maccr().modify(|w| {
w.set_ifg(Ifg::IFG96); // inter frame gap 96 bit times
w.set_apcs(Apcs::STRIP); // automatic padding and crc stripping
w.set_fes(Fes::FES100); // fast ethernet speed
w.set_dm(Dm::FULLDUPLEX); // full duplex
// TODO: Carrier sense ? ECRSFD
});
// Note: Writing to LR triggers synchronisation of both LR and HR into the MAC core,
// so the LR write must happen after the HR write.
mac.maca0hr()
.modify(|w| w.set_maca0h(u16::from(mac_addr[4]) | (u16::from(mac_addr[5]) << 8)));
mac.maca0lr().write(|w| {
w.set_maca0l(
u32::from(mac_addr[0])
| (u32::from(mac_addr[1]) << 8)
| (u32::from(mac_addr[2]) << 16)
| (u32::from(mac_addr[3]) << 24),
)
});
// pause time
mac.macfcr().modify(|w| w.set_pt(0x100));
// Transfer and Forward, Receive and Forward
dma.dmaomr().modify(|w| {
w.set_tsf(Tsf::STOREFORWARD);
w.set_rsf(Rsf::STOREFORWARD);
});
dma.dmabmr().modify(|w| {
w.set_pbl(Pbl::PBL32) // programmable burst length - 32 ?
});
// TODO MTU size setting not found for v1 ethernet, check if correct
// NOTE(unsafe) We got the peripheral singleton, which means that `rcc::init` was called
let hclk = crate::rcc::get_freqs().ahb1;
let hclk_mhz = hclk.0 / 1_000_000;
// Set the MDC clock frequency in the range 1MHz - 2.5MHz
let clock_range = match hclk_mhz {
0..=24 => panic!("Invalid HCLK frequency - should be at least 25 MHz."),
25..=34 => Cr::CR_20_35, // Divide by 16
35..=59 => Cr::CR_35_60, // Divide by 26
60..=99 => Cr::CR_60_100, // Divide by 42
100..=149 => Cr::CR_100_150, // Divide by 62
150..=216 => Cr::CR_150_168, // Divide by 102
_ => {
panic!("HCLK results in MDC clock > 2.5MHz even for the highest CSR clock divider")
}
};
let pins = [
ref_clk.degrade(),
mdio.degrade(),
mdc.degrade(),
crs.degrade(),
rx_d0.degrade(),
rx_d1.degrade(),
tx_d0.degrade(),
tx_d1.degrade(),
tx_en.degrade(),
];
let mut this = Self {
state,
pins,
_phy: phy,
clock_range,
phy_addr,
mac_addr,
};
this.state.with(|s| {
s.desc_ring.init();
fence(Ordering::SeqCst);
let mac = ETH.ethernet_mac();
let dma = ETH.ethernet_dma();
mac.maccr().modify(|w| {
w.set_re(true);
w.set_te(true);
});
dma.dmaomr().modify(|w| {
w.set_ftf(Ftf::FLUSH); // flush transmit fifo (queue)
w.set_st(St::STARTED); // start transmitting channel
w.set_sr(DmaomrSr::STARTED); // start receiving channel
});
// Enable interrupts
dma.dmaier().modify(|w| {
w.set_nise(true);
w.set_rie(true);
w.set_tie(true);
});
});
P::phy_reset(&mut this);
P::phy_init(&mut this);
this
}
}
unsafe impl<'d, T: Instance, P: PHY, const TX: usize, const RX: usize> StationManagement
for Ethernet<'d, T, P, TX, RX>
{
fn smi_read(&mut self, reg: u8) -> u16 {
// NOTE(unsafe) These registers aren't used in the interrupt and we have `&mut self`
unsafe {
let mac = ETH.ethernet_mac();
mac.macmiiar().modify(|w| {
w.set_pa(self.phy_addr);
w.set_mr(reg);
w.set_mw(Mw::READ); // read operation
w.set_cr(self.clock_range);
w.set_mb(MbProgress::BUSY); // indicate that operation is in progress
});
while mac.macmiiar().read().mb() == MbProgress::BUSY {}
mac.macmiidr().read().md()
}
}
fn smi_write(&mut self, reg: u8, val: u16) {
// NOTE(unsafe) These registers aren't used in the interrupt and we have `&mut self`
unsafe {
let mac = ETH.ethernet_mac();
mac.macmiidr().write(|w| w.set_md(val));
mac.macmiiar().modify(|w| {
w.set_pa(self.phy_addr);
w.set_mr(reg);
w.set_mw(Mw::WRITE); // write
w.set_cr(self.clock_range);
w.set_mb(MbProgress::BUSY);
});
while mac.macmiiar().read().mb() == MbProgress::BUSY {}
}
}
}
impl<'d, T: Instance, P: PHY, const TX: usize, const RX: usize> Device
for Ethernet<'d, T, P, TX, RX>
{
fn is_transmit_ready(&mut self) -> bool {
self.state.with(|s| s.desc_ring.tx.available())
}
fn transmit(&mut self, pkt: PacketBuf) {
self.state.with(|s| unwrap!(s.desc_ring.tx.transmit(pkt)));
}
fn receive(&mut self) -> Option<PacketBuf> {
self.state.with(|s| s.desc_ring.rx.pop_packet())
}
fn register_waker(&mut self, waker: &Waker) {
WAKER.register(waker);
}
fn capabilities(&mut self) -> DeviceCapabilities {
let mut caps = DeviceCapabilities::default();
caps.max_transmission_unit = MTU;
caps.max_burst_size = Some(TX.min(RX));
caps
}
fn link_state(&mut self) -> LinkState {
if P::poll_link(self) {
LinkState::Up
} else {
LinkState::Down
}
}
fn ethernet_address(&mut self) -> [u8; 6] {
self.mac_addr
}
}
impl<'d, T: Instance, P: PHY, const TX: usize, const RX: usize> Drop
for Ethernet<'d, T, P, TX, RX>
{
fn drop(&mut self) {
// NOTE(unsafe) We have `&mut self` and the interrupt doesn't use this registers
unsafe {
let dma = ETH.ethernet_dma();
let mac = ETH.ethernet_mac();
// Disable the TX DMA and wait for any previous transmissions to be completed
dma.dmaomr().modify(|w| w.set_st(St::STOPPED));
// Disable MAC transmitter and receiver
mac.maccr().modify(|w| {
w.set_re(false);
w.set_te(false);
});
dma.dmaomr().modify(|w| w.set_sr(DmaomrSr::STOPPED));
}
// NOTE(unsafe) Exclusive access to the regs
critical_section::with(|_| unsafe {
for pin in self.pins.iter_mut() {
pin.set_as_disconnected();
}
})
}
}
//----------------------------------------------------------------------
struct Inner<'d, T: Instance, const TX: usize, const RX: usize> {
_peri: PhantomData<&'d mut T>,
desc_ring: DescriptorRing<TX, RX>,
}
impl<'d, T: Instance, const TX: usize, const RX: usize> Inner<'d, T, TX, RX> {
pub fn new(_peri: impl Unborrow<Target = T> + 'd) -> Self {
Self {
_peri: PhantomData,
desc_ring: DescriptorRing::new(),
}
}
}
impl<'d, T: Instance, const TX: usize, const RX: usize> PeripheralState for Inner<'d, T, TX, RX> {
type Interrupt = crate::interrupt::ETH;
fn on_interrupt(&mut self) {
unwrap!(self.desc_ring.tx.on_interrupt());
self.desc_ring.rx.on_interrupt();
WAKER.wake();
// TODO: Check and clear more flags
unsafe {
let dma = ETH.ethernet_dma();
dma.dmasr().modify(|w| {
w.set_ts(true);
w.set_rs(true);
w.set_nis(true);
});
// Delay two peripheral's clock
dma.dmasr().read();
dma.dmasr().read();
}
}
}
static WAKER: AtomicWaker = AtomicWaker::new();

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embassy-stm32/src/eth/v1a/rx_desc.rs Normal file
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use core::sync::atomic::{compiler_fence, fence, Ordering};
use embassy_net::{Packet, PacketBox, PacketBoxExt, PacketBuf};
use stm32_metapac::eth::vals::{DmaomrSr, Rpd, Rps};
use vcell::VolatileCell;
use crate::pac::ETH;
mod rx_consts {
/// Owned by DMA engine
pub const RXDESC_0_OWN: u32 = 1 << 31;
/// First descriptor
pub const RXDESC_0_FS: u32 = 1 << 9;
/// Last descriptor
pub const RXDESC_0_LS: u32 = 1 << 8;
/// Error summary
pub const RXDESC_0_ES: u32 = 1 << 15;
/// Frame length
pub const RXDESC_0_FL_MASK: u32 = 0x3FFF;
pub const RXDESC_0_FL_SHIFT: usize = 16;
pub const RXDESC_1_RBS_MASK: u32 = 0x0fff;
/// Second address chained
pub const RXDESC_1_RCH: u32 = 1 << 14;
/// End Of Ring
pub const RXDESC_1_RER: u32 = 1 << 15;
}
use rx_consts::*;
/// Receive Descriptor representation
///
/// * rdes0: OWN and Status
/// * rdes1: allocated buffer length
/// * rdes2: data buffer address
/// * rdes3: next descriptor address
#[repr(C)]
struct RDes {
rdes0: VolatileCell<u32>,
rdes1: VolatileCell<u32>,
rdes2: VolatileCell<u32>,
rdes3: VolatileCell<u32>,
}
impl RDes {
pub const fn new() -> Self {
Self {
rdes0: VolatileCell::new(0),
rdes1: VolatileCell::new(0),
rdes2: VolatileCell::new(0),
rdes3: VolatileCell::new(0),
}
}
/// Return true if this RDes is acceptable to us
#[inline(always)]
pub fn valid(&self) -> bool {
// Write-back descriptor is valid if:
//
// Contains first buffer of packet AND contains last buf of
// packet AND no errors
(self.rdes0.get() & (RXDESC_0_ES | RXDESC_0_FS | RXDESC_0_LS))
== (RXDESC_0_FS | RXDESC_0_LS)
}
/// Return true if this RDes is not currently owned by the DMA
#[inline(always)]
pub fn available(&self) -> bool {
self.rdes0.get() & RXDESC_0_OWN == 0 // Owned by us
}
/// Configures the reception buffer address and length and passed descriptor ownership to the DMA
#[inline(always)]
pub fn set_ready(&mut self, buf_addr: u32, buf_len: usize) {
self.rdes1
.set(self.rdes1.get() | (buf_len as u32) & RXDESC_1_RBS_MASK);
self.rdes2.set(buf_addr);
// "Preceding reads and writes cannot be moved past subsequent writes."
fence(Ordering::Release);
compiler_fence(Ordering::Release);
self.rdes0.set(self.rdes0.get() | RXDESC_0_OWN);
// Used to flush the store buffer as fast as possible to make the buffer available for the
// DMA.
fence(Ordering::SeqCst);
}
// points to next descriptor (RCH)
#[inline(always)]
fn set_buffer2(&mut self, buffer: *const u8) {
self.rdes3.set(buffer as u32);
}
#[inline(always)]
fn set_end_of_ring(&mut self) {
self.rdes1.set(self.rdes1.get() | RXDESC_1_RER);
}
#[inline(always)]
fn packet_len(&self) -> usize {
((self.rdes0.get() >> RXDESC_0_FL_SHIFT) & RXDESC_0_FL_MASK) as usize
}
pub fn setup(&mut self, next: Option<&Self>) {
// Defer this initialization to this function, so we can have `RingEntry` on bss.
self.rdes1.set(self.rdes1.get() | RXDESC_1_RCH);
match next {
Some(next) => self.set_buffer2(next as *const _ as *const u8),
None => {
self.set_buffer2(0 as *const u8);
self.set_end_of_ring();
}
}
}
}
/// Running state of the `RxRing`
#[derive(PartialEq, Eq, Debug)]
pub enum RunningState {
Unknown,
Stopped,
Running,
}
impl RunningState {
/// whether self equals to `RunningState::Running`
pub fn is_running(&self) -> bool {
*self == RunningState::Running
}
}
/// Rx ring of descriptors and packets
///
/// This ring has three major locations that work in lock-step. The DMA will never write to the tail
/// index, so the `read_index` must never pass the tail index. The `next_tail_index` is always 1
/// slot ahead of the real tail index, and it must never pass the `read_index` or it could overwrite
/// a packet still to be passed to the application.
///
/// nt can't pass r (no alloc)
/// +---+---+---+---+ Read ok +---+---+---+---+ No Read +---+---+---+---+
/// | | | | | ------------> | | | | | ------------> | | | | |
/// +---+---+---+---+ Allocation ok +---+---+---+---+ +---+---+---+---+
/// ^ ^t ^t ^ ^t ^
/// |r |r |r
/// |nt |nt |nt
///
///
/// +---+---+---+---+ Read ok +---+---+---+---+ Can't read +---+---+---+---+
/// | | | | | ------------> | | | | | ------------> | | | | |
/// +---+---+---+---+ Allocation fail +---+---+---+---+ Allocation ok +---+---+---+---+
/// ^ ^t ^ ^t ^ ^ ^ ^t
/// |r | |r | | |r
/// |nt |nt |nt
///
pub(crate) struct RDesRing<const N: usize> {
descriptors: [RDes; N],
buffers: [Option<PacketBox>; N],
read_index: usize,
next_tail_index: usize,
}
impl<const N: usize> RDesRing<N> {
pub const fn new() -> Self {
const RDES: RDes = RDes::new();
const BUFFERS: Option<PacketBox> = None;
Self {
descriptors: [RDES; N],
buffers: [BUFFERS; N],
read_index: 0,
next_tail_index: 0,
}
}
pub(crate) fn init(&mut self) {
assert!(N > 1);
let mut last_index = 0;
for (index, buf) in self.buffers.iter_mut().enumerate() {
let pkt = match PacketBox::new(Packet::new()) {
Some(p) => p,
None => {
if index == 0 {
panic!("Could not allocate at least one buffer for Ethernet receiving");
} else {
break;
}
}
};
self.descriptors[index].set_ready(pkt.as_ptr() as u32, pkt.len());
*buf = Some(pkt);
last_index = index;
}
self.next_tail_index = (last_index + 1) % N;
// not sure if this is supposed to span all of the descriptor or just those that contain buffers
{
let mut previous: Option<&mut RDes> = None;
for entry in self.descriptors.iter_mut() {
if let Some(prev) = &mut previous {
prev.setup(Some(entry));
}
previous = Some(entry);
}
if let Some(entry) = &mut previous {
entry.setup(None);
}
}
// Register txdescriptor start
// NOTE (unsafe) Used for atomic writes
unsafe {
ETH.ethernet_dma()
.dmardlar()
.write(|w| w.0 = &self.descriptors as *const _ as u32);
};
// We already have fences in `set_owned`, which is called in `setup`
// Start receive
unsafe {
ETH.ethernet_dma()
.dmaomr()
.modify(|w| w.set_sr(DmaomrSr::STARTED))
};
self.demand_poll();
}
fn demand_poll(&self) {
unsafe { ETH.ethernet_dma().dmarpdr().write(|w| w.set_rpd(Rpd::POLL)) };
}
pub(crate) fn on_interrupt(&mut self) {
// XXX: Do we need to do anything here ? Maybe we should try to advance the tail ptr, but it
// would soon hit the read ptr anyway, and we will wake smoltcp's stack on the interrupt
// which should try to pop a packet...
}
/// Get current `RunningState`
fn running_state(&self) -> RunningState {
match unsafe { ETH.ethernet_dma().dmasr().read().rps() } {
// Reset or Stop Receive Command issued
Rps::STOPPED => RunningState::Stopped,
// Fetching receive transfer descriptor
Rps::RUNNINGFETCHING => RunningState::Running,
// Waiting for receive packet
Rps::RUNNINGWAITING => RunningState::Running,
// Receive descriptor unavailable
Rps::SUSPENDED => RunningState::Stopped,
// Closing receive descriptor
Rps(0b101) => RunningState::Running,
// Transferring the receive packet data from receive buffer to host memory
Rps::RUNNINGWRITING => RunningState::Running,
_ => RunningState::Unknown,
}
}
pub(crate) fn pop_packet(&mut self) -> Option<PacketBuf> {
if !self.running_state().is_running() {
self.demand_poll();
}
// Not sure if the contents of the write buffer on the M7 can affects reads, so we are using
// a DMB here just in case, it also serves as a hint to the compiler that we're syncing the
// buffer (I think .-.)
fence(Ordering::SeqCst);
let read_available = self.descriptors[self.read_index].available();
let tail_index = (self.next_tail_index + N - 1) % N;
let pkt = if read_available && self.read_index != tail_index {
let pkt = self.buffers[self.read_index].take();
let len = self.descriptors[self.read_index].packet_len();
assert!(pkt.is_some());
let valid = self.descriptors[self.read_index].valid();
self.read_index = (self.read_index + 1) % N;
if valid {
pkt.map(|p| p.slice(0..len))
} else {
None
}
} else {
None
};
// Try to advance the tail_index
if self.next_tail_index != self.read_index {
match PacketBox::new(Packet::new()) {
Some(b) => {
let addr = b.as_ptr() as u32;
let buffer_len = b.len();
self.buffers[self.next_tail_index].replace(b);
self.descriptors[self.next_tail_index].set_ready(addr, buffer_len);
// "Preceding reads and writes cannot be moved past subsequent writes."
fence(Ordering::Release);
self.next_tail_index = (self.next_tail_index + 1) % N;
}
None => {}
}
}
pkt
}
}

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embassy-stm32/src/eth/v1a/tx_desc.rs Normal file
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use core::sync::atomic::{compiler_fence, fence, Ordering};
use embassy_net::PacketBuf;
use stm32_metapac::eth::vals::St;
use vcell::VolatileCell;
use crate::pac::ETH;
#[non_exhaustive]
#[derive(Debug, Copy, Clone)]
#[cfg_attr(feature = "defmt", derive(defmt::Format))]
pub enum Error {
NoBufferAvailable,
// TODO: Break down this error into several others
TransmissionError,
}
/// Transmit and Receive Descriptor fields
#[allow(dead_code)]
mod tx_consts {
pub const TXDESC_0_OWN: u32 = 1 << 31;
pub const TXDESC_0_IOC: u32 = 1 << 30;
// First segment of frame
pub const TXDESC_0_FS: u32 = 1 << 28;
// Last segment of frame
pub const TXDESC_0_LS: u32 = 1 << 29;
// Transmit end of ring
pub const TXDESC_0_TER: u32 = 1 << 21;
// Second address chained
pub const TXDESC_0_TCH: u32 = 1 << 20;
// Error status
pub const TXDESC_0_ES: u32 = 1 << 15;
// Transmit buffer size
pub const TXDESC_1_TBS_SHIFT: usize = 0;
pub const TXDESC_1_TBS_MASK: u32 = 0x0fff << TXDESC_1_TBS_SHIFT;
}
use tx_consts::*;
/// Transmit Descriptor representation
///
/// * tdes0: control
/// * tdes1: buffer lengths
/// * tdes2: data buffer address
/// * tdes3: next descriptor address
#[repr(C)]
struct TDes {
tdes0: VolatileCell<u32>,
tdes1: VolatileCell<u32>,
tdes2: VolatileCell<u32>,
tdes3: VolatileCell<u32>,
}
impl TDes {
pub const fn new() -> Self {
Self {
tdes0: VolatileCell::new(0),
tdes1: VolatileCell::new(0),
tdes2: VolatileCell::new(0),
tdes3: VolatileCell::new(0),
}
}
/// Return true if this TDes is not currently owned by the DMA
pub fn available(&self) -> bool {
(self.tdes0.get() & TXDESC_0_OWN) == 0
}
/// Pass ownership to the DMA engine
fn set_owned(&mut self) {
// "Preceding reads and writes cannot be moved past subsequent writes."
fence(Ordering::Release);
compiler_fence(Ordering::Release);
self.tdes0.set(self.tdes0.get() | TXDESC_0_OWN);
// Used to flush the store buffer as fast as possible to make the buffer available for the
// DMA.
fence(Ordering::SeqCst);
}
fn set_buffer1(&mut self, buffer: *const u8) {
self.tdes2.set(buffer as u32);
}
fn set_buffer1_len(&mut self, len: usize) {
self.tdes1
.set((self.tdes1.get() & !TXDESC_1_TBS_MASK) | ((len as u32) << TXDESC_1_TBS_SHIFT));
}
// points to next descriptor (RCH)
fn set_buffer2(&mut self, buffer: *const u8) {
self.tdes3.set(buffer as u32);
}
fn set_end_of_ring(&mut self) {
self.tdes0.set(self.tdes0.get() | TXDESC_0_TER);
}
// set up as a part fo the ring buffer - configures the tdes
pub fn setup(&mut self, next: Option<&Self>) {
// Defer this initialization to this function, so we can have `RingEntry` on bss.
self.tdes0
.set(TXDESC_0_TCH | TXDESC_0_IOC | TXDESC_0_FS | TXDESC_0_LS);
match next {
Some(next) => self.set_buffer2(next as *const TDes as *const u8),
None => {
self.set_buffer2(0 as *const u8);
self.set_end_of_ring();
}
}
}
}
pub(crate) struct TDesRing<const N: usize> {
descriptors: [TDes; N],
buffers: [Option<PacketBuf>; N],
next_entry: usize,
}
impl<const N: usize> TDesRing<N> {
pub const fn new() -> Self {
const TDES: TDes = TDes::new();
const BUFFERS: Option<PacketBuf> = None;
Self {
descriptors: [TDES; N],
buffers: [BUFFERS; N],
next_entry: 0,
}
}
/// Initialise this TDesRing. Assume TDesRing is corrupt
///
/// The current memory address of the buffers inside this TDesRing
/// will be stored in the descriptors, so ensure the TDesRing is
/// not moved after initialisation.
pub(crate) fn init(&mut self) {
assert!(N > 0);
{
let mut previous: Option<&mut TDes> = None;
for entry in self.descriptors.iter_mut() {
if let Some(prev) = &mut previous {
prev.setup(Some(entry));
}
previous = Some(entry);
}
if let Some(entry) = &mut previous {
entry.setup(None);
}
}
self.next_entry = 0;
// Register txdescriptor start
// NOTE (unsafe) Used for atomic writes
unsafe {
ETH.ethernet_dma()
.dmatdlar()
.write(|w| w.0 = &self.descriptors as *const _ as u32);
}
// "Preceding reads and writes cannot be moved past subsequent writes."
#[cfg(feature = "fence")]
fence(Ordering::Release);
// We don't need a compiler fence here because all interactions with `Descriptor` are
// volatiles
// Start transmission
unsafe {
ETH.ethernet_dma()
.dmaomr()
.modify(|w| w.set_st(St::STARTED))
};
}
/// Return true if a TDes is available for use
pub(crate) fn available(&self) -> bool {
self.descriptors[self.next_entry].available()
}
pub(crate) fn transmit(&mut self, pkt: PacketBuf) -> Result<(), Error> {
if !self.available() {
return Err(Error::NoBufferAvailable);
}
let descriptor = &mut self.descriptors[self.next_entry];
let pkt_len = pkt.len();
let address = pkt.as_ptr() as *const u8;
descriptor.set_buffer1(address);
descriptor.set_buffer1_len(pkt_len);
self.buffers[self.next_entry].replace(pkt);
descriptor.set_owned();
// Ensure changes to the descriptor are committed before DMA engine sees tail pointer store.
// This will generate an DMB instruction.
// "Preceding reads and writes cannot be moved past subsequent writes."
fence(Ordering::Release);
// Move the tail pointer (TPR) to the next descriptor
self.next_entry = (self.next_entry + 1) % N;
// Request the DMA engine to poll the latest tx descriptor
unsafe { ETH.ethernet_dma().dmatpdr().modify(|w| w.0 = 1) }
Ok(())
}
pub(crate) fn on_interrupt(&mut self) -> Result<(), Error> {
let previous = (self.next_entry + N - 1) % N;
let td = &self.descriptors[previous];
// DMB to ensure that we are reading an updated value, probably not needed at the hardware
// level, but this is also a hint to the compiler that we're syncing on the buffer.
fence(Ordering::SeqCst);
let tdes0 = td.tdes0.get();
if tdes0 & TXDESC_0_OWN != 0 {
// Transmission isn't done yet, probably a receive interrupt that fired this
return Ok(());
}
// Release the buffer
self.buffers[previous].take();
if tdes0 & TXDESC_0_ES != 0 {
Err(Error::TransmissionError)
} else {
Ok(())
}
}
}