zynq-rs/libboard_zynq/src/eth/tx.rs

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use core::ops::{Deref, DerefMut};
use alloc::{vec, vec::Vec};
use libcortex_a9::{cache::dcc_slice, UncachedSlice};
use libregister::*;
use super::{Buffer, regs};
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/// Descriptor entry
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#[repr(C, align(0x08))]
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pub struct DescEntry {
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word0: DescWord0,
word1: DescWord1,
}
register!(desc_word0, DescWord0, VolatileCell, u32);
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register_bits!(desc_word0, address, u32, 0, 31);
register!(desc_word1, DescWord1, VolatileCell, u32);
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register_bits!(desc_word1, length, u16, 0, 13);
register_bit!(desc_word1, last_buffer, 15);
register_bit!(desc_word1, no_crc_append, 16);
register_bits!(desc_word1, csum_offload_errors, u8, 20, 22);
register_bit!(desc_word1, late_collision_tx_error, 26);
register_bit!(desc_word1, ahb_frame_corruption, 27);
register_bit!(desc_word1, retry_limit_exceeded, 29);
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register_bit!(desc_word1,
/// marks last descriptor in list
wrap, 30);
register_bit!(desc_word1,
/// true if owned by software, false if owned by hardware
used, 31);
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impl DescEntry {
pub fn zeroed() -> Self {
DescEntry {
word0: DescWord0 { inner: VolatileCell::new(0) },
word1: DescWord1 { inner: VolatileCell::new(0) },
}
}
}
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/// Number of descriptors
pub const DESCS: usize = 8;
#[repr(C)]
pub struct DescList {
list: UncachedSlice<DescEntry>,
buffers: Vec<Buffer>,
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next: usize,
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}
impl DescList {
pub fn new(size: usize) -> Self {
let mut list = UncachedSlice::new(size, || DescEntry::zeroed())
.unwrap();
let mut buffers = vec![Buffer::new(); size];
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let last = list.len().min(buffers.len()) - 1;
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// Sending seems to not work properly with only one packet
// buffer (two duplicates get send with every packet), so
// check that at least 2 are allocated, i.e. that the index of
// the last one is at least one.
assert!(last > 0);
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for (i, (entry, buffer)) in list.iter_mut().zip(buffers.iter_mut()).enumerate() {
let is_last = i == last;
let buffer_addr = &mut buffer.0[0] as *mut _ as u32;
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assert!(buffer_addr & 0b11 == 0);
entry.word0.write(
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DescWord0::zeroed()
.address(buffer_addr)
);
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entry.word1.write(
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DescWord1::zeroed()
.used(true)
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.wrap(is_last)
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// every frame contains 1 packet
.last_buffer(true)
);
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}
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DescList {
list,
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buffers,
next: 0,
}
}
pub fn len(&self) -> usize {
self.list.len().min(self.buffers.len())
}
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pub fn list_addr(&self) -> u32 {
&self.list[0] as *const _ as u32
}
pub fn send<'s: 'p, 'p>(&'s mut self, regs: &'s mut regs::RegisterBlock, length: usize) -> Option<PktRef<'p>> {
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let list_len = self.list.len();
let entry = &mut self.list[self.next];
if entry.word1.read().used() {
let buffer = &mut self.buffers[self.next][0..length];
entry.word1.write(DescWord1::zeroed()
.length(length as u16)
.last_buffer(true)
.wrap(self.next >= list_len - 1)
.used(true)
);
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self.next += 1;
if self.next >= list_len {
self.next = 0;
}
Some(PktRef { entry, buffer, regs })
} else {
// Still in use by HW (sending too fast, ring exceeded)
None
}
}
}
/// Releases a buffer back to the HW upon Drop, and start the TX
/// engine
pub struct PktRef<'a> {
entry: &'a mut DescEntry,
buffer: &'a mut [u8],
regs: &'a mut regs::RegisterBlock,
}
impl<'a> Drop for PktRef<'a> {
fn drop(&mut self) {
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// Write back all dirty cachelines of this buffer
dcc_slice(self.buffer);
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self.entry.word1.modify(|_, w| w.used(false));
if ! self.regs.tx_status.read().tx_go() {
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// Start TX if not already running
self.regs.net_ctrl.modify(|_, w| w.start_tx(true));
}
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}
}
impl<'a> Deref for PktRef<'a> {
type Target = [u8];
fn deref(&self) -> &Self::Target {
self.buffer
}
}
impl<'a> DerefMut for PktRef<'a> {
fn deref_mut(&mut self) -> &mut <Self as Deref>::Target {
self.buffer
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}
}
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/// TxToken for smoltcp support
pub struct Token<'a> {
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pub regs: &'a mut regs::RegisterBlock,
pub desc_list: &'a mut DescList,
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}
impl<'a> smoltcp::phy::TxToken for Token<'a> {
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fn consume<R, F>(self, _timestamp: smoltcp::time::Instant, len: usize, f: F) -> smoltcp::Result<R>
where F: FnOnce(&mut [u8]) -> smoltcp::Result<R>
{
match self.desc_list.send(self.regs, len) {
None =>
Err(smoltcp::Error::Exhausted),
Some(mut pktref) => {
let result = f(pktref.deref_mut());
// TODO: on result.is_err() don;t send
drop(pktref);
result
}
}
}
}