zynq-rs/src/uart/mod.rs

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Rust
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use core::fmt;
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use volatile_register::RW;
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use crate::regs::*;
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use crate::slcr;
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mod regs;
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mod baud_rate_gen;
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/// Determined through experimentation. Actually supposed to be
/// 1 GHz (IO PLL) / 0x14 (slcr.UART_CLK_CTRL[DIVISOR]) = 50 MHz.
const UART_REF_CLK: u32 = 45_000_000;
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pub struct Uart {
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regs: &'static mut regs::RegisterBlock,
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}
impl Uart {
pub fn uart1(baudrate: u32) -> Self {
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slcr::RegisterBlock::unlocked(|slcr| {
slcr.uart_rst_ctrl.reset_uart1();
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// Route UART 1 RxD/TxD Signals to MIO Pins
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// TX pin
slcr.mio_pin_48.write(
slcr::MioPin48::zeroed()
.l3_sel(0b111)
.io_type(0b001)
.pullup(true)
);
// RX pin
slcr.mio_pin_49.write(
slcr::MioPin49::zeroed()
.tri_enable(true)
.l3_sel(0b111)
.io_type(0b001)
.pullup(true)
);
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slcr.aper_clk_ctrl.enable_uart1();
slcr.uart_clk_ctrl.enable_uart1();
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});
let mut self_ = Uart {
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regs: regs::RegisterBlock::uart1(),
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};
self_.configure(baudrate);
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self_
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}
pub fn write_byte(&mut self, value: u8) {
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while self.tx_fifo_full() {}
self.regs.tx_rx_fifo.write(
regs::TxRxFifo::zeroed()
.data(value.into())
);
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}
pub fn configure(&mut self, baudrate: u32) {
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// Configure UART character frame
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// * Disable clock-divider
// * 8-bit
// * 1 stop bit
// * Normal channel mode
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// * No parity
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self.regs.mode.write(
regs::Mode::zeroed()
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.par(regs::ParityMode::None)
.chmode(regs::ChannelMode::Normal)
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);
// Configure the Baud Rate
self.disable_rx();
self.disable_tx();
baud_rate_gen::configure(self.regs, UART_REF_CLK, baudrate);
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// Enable controller
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self.reset_rx();
self.reset_tx();
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self.wait_reset();
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self.enable_rx();
self.enable_tx();
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self.set_rx_timeout(false);
self.set_break(false, true);
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}
fn disable_rx(&mut self) {
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self.regs.control.modify(|_, w| {
w.rxen(false)
.rxdis(true)
})
}
fn disable_tx(&mut self) {
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self.regs.control.modify(|_, w| {
w.txen(false)
.txdis(true)
})
}
fn enable_rx(&mut self) {
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self.regs.control.modify(|_, w| {
w.rxen(true)
.rxdis(false)
})
}
fn enable_tx(&mut self) {
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self.regs.control.modify(|_, w| {
w.txen(true)
.txdis(false)
})
}
fn reset_rx(&mut self) {
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self.regs.control.modify(|_, w| {
w.rxrst(true)
})
}
fn reset_tx(&mut self) {
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self.regs.control.modify(|_, w| {
w.txrst(true)
})
}
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/// Wait for `reset_rx()` or `reset_tx()` to complete
fn wait_reset(&self) {
let mut pending = true;
while pending {
let control = self.regs.control.read();
pending = control.rxrst() || control.txrst();
}
}
fn set_break(&mut self, startbrk: bool, stopbrk: bool) {
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self.regs.control.modify(|_, w| {
w.sttbrk(startbrk)
.stpbrk(stopbrk)
})
}
// 0 disables
fn set_rx_timeout(&mut self, enable: bool) {
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self.regs.control.modify(|_, w| {
w.rstto(enable)
})
}
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pub fn tx_fifo_full(&self) -> bool {
self.regs.channel_sts.read().txfull()
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}
pub fn tx_fifo_empty(&self) -> bool {
self.regs.channel_sts.read().txempty()
}
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}
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impl fmt::Write for Uart {
fn write_str(&mut self, s: &str) -> Result<(), fmt::Error> {
while !self.tx_fifo_empty() {}
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for b in s.bytes() {
self.write_byte(b);
}
Ok(())
}
}