Bare-metal Rust on the Xilinx Zynq ZC706 devkit
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use core::ops::Deref;
use vcell::VolatileCell;
use crate::{register, register_bit, register_bits, regs::*};
use super::MTU;
#[derive(Debug)]
pub enum Error {
HrespNotOk,
RxOverrun,
BufferNotAvail,
Truncated,
}
/// Descriptor entry
#[repr(C, align(0x08))]
pub struct DescEntry {
word0: DescWord0,
word1: DescWord1,
}
impl DescEntry {
pub fn zeroed() -> Self {
DescEntry {
word0: DescWord0 { inner: VolatileCell::new(0) },
word1: DescWord1 { inner: VolatileCell::new(0) },
}
}
}
register!(desc_word0, DescWord0, VolatileCell, u32);
register_bit!(desc_word0,
/// true if owned by software, false if owned by hardware
used, 0);
register_bit!(desc_word0,
/// mark last desc in list
wrap, 1);
register_bits!(desc_word0, address, u32, 2, 31);
register!(desc_word1, DescWord1, VolatileCell, u32);
register_bits!(desc_word1, frame_length_lsbs, u16, 0, 12);
register_bit!(desc_word1, bad_fcs, 13);
register_bit!(desc_word1, start_of_frame, 14);
register_bit!(desc_word1, end_of_frame, 15);
register_bit!(desc_word1, cfi, 16);
register_bits!(desc_word1, vlan_priority, u8, 17, 19);
register_bit!(desc_word1, priority_tag, 20);
register_bit!(desc_word1, vlan_tag, 21);
register_bits!(desc_word1, bits_22_23, u8, 22, 23);
register_bit!(desc_word1, bit_24, 24);
register_bits!(desc_word1, spec_addr_which, u8, 25, 26);
register_bit!(desc_word1, spec_addr_match, 27);
register_bit!(desc_word1, uni_hash_match, 29);
register_bit!(desc_word1, multi_hash_match, 30);
register_bit!(desc_word1, global_broadcast, 31);
#[repr(C)]
pub struct DescList<'a> {
list: &'a mut [DescEntry],
buffers: &'a mut [[u8; MTU]],
next: usize,
}
impl<'a> DescList<'a> {
pub fn new(list: &'a mut [DescEntry], buffers: &'a mut [[u8; MTU]]) -> Self {
let last = list.len().min(buffers.len()) - 1;
for (i, (entry, buffer)) in list.iter_mut().zip(buffers.iter_mut()).enumerate() {
let is_last = i == last;
let buffer_addr = &mut buffer[0] as *mut _ as u32;
assert!(buffer_addr & 0b11 == 0);
entry.word0.write(
DescWord0::zeroed()
.used(false)
.wrap(is_last)
.address(buffer_addr >> 2)
);
entry.word1.write(
DescWord1::zeroed()
);
}
DescList {
// Shorten the list of descriptors to the required number.
list: &mut list[0..=last],
buffers,
next: 0,
}
}
pub fn list_addr(&self) -> u32 {
&self.list[0] as *const _ as u32
}
pub fn recv_next<'s: 'p, 'p>(&'s mut self) -> Result<Option<PktRef<'p>>, Error> {
let list_len = self.list.len();
let entry = &mut self.list[self.next];
if entry.word0.read().used() {
let word1 = entry.word1.read();
let len = word1.frame_length_lsbs().into();
let buffer = &mut self.buffers[self.next][0..len];
self.next += 1;
if self.next >= list_len {
self.next = 0;
}
let pkt = PktRef { entry, buffer };
if word1.start_of_frame() && word1.end_of_frame() {
Ok(Some(pkt))
} else {
Err(Error::Truncated)
}
} else {
Ok(None)
}
}
}
/// Releases a buffer back to the HW upon Drop
pub struct PktRef<'a> {
entry: &'a mut DescEntry,
buffer: &'a mut [u8],
}
impl<'a> Drop for PktRef<'a> {
fn drop(&mut self) {
self.entry.word0.modify(|_, w| w.used(false));
}
}
impl<'a> Deref for PktRef<'a> {
type Target = [u8];
fn deref(&self) -> &Self::Target {
self.buffer
}
}
impl<'a> smoltcp::phy::RxToken for PktRef<'a> {
fn consume<R, F>(self, _timestamp: smoltcp::time::Instant, f: F) -> smoltcp::Result<R>
where
F: FnOnce(&mut [u8]) -> smoltcp::Result<R>
{
f(self.buffer)
}
}