embassy/embassy-rp/src/spi.rs

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use core::marker::PhantomData;
use embassy::util::Unborrow;
use embassy_hal_common::unborrow;
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use embedded_hal::blocking::spi as eh;
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use embedded_hal::spi as ehnb;
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use crate::gpio::sealed::Pin as _;
use crate::gpio::{NoPin, OptionalPin};
use crate::{pac, peripherals};
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pub use ehnb::{Phase, Polarity};
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#[non_exhaustive]
pub struct Config {
pub frequency: u32,
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pub phase: ehnb::Phase,
pub polarity: ehnb::Polarity,
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}
impl Default for Config {
fn default() -> Self {
Self {
frequency: 1_000_000,
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phase: ehnb::Phase::CaptureOnFirstTransition,
polarity: ehnb::Polarity::IdleLow,
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}
}
}
pub struct Spi<'d, T: Instance> {
inner: T,
phantom: PhantomData<&'d mut T>,
}
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fn div_roundup(a: u32, b: u32) -> u32 {
(a + b - 1) / b
}
fn calc_prescs(freq: u32) -> (u8, u8) {
let clk_peri = crate::clocks::clk_peri_freq();
// final SPI frequency: spi_freq = clk_peri / presc / postdiv
// presc must be in 2..=254, and must be even
// postdiv must be in 1..=256
// divide extra by 2, so we get rid of the "presc must be even" requirement
let ratio = div_roundup(clk_peri, freq * 2);
if ratio > 127 * 256 {
panic!("Requested too low SPI frequency");
}
let presc = div_roundup(ratio, 256);
let postdiv = if presc == 1 {
ratio
} else {
div_roundup(ratio, presc)
};
((presc * 2) as u8, (postdiv - 1) as u8)
}
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impl<'d, T: Instance> Spi<'d, T> {
pub fn new(
inner: impl Unborrow<Target = T>,
clk: impl Unborrow<Target = impl ClkPin<T>>,
mosi: impl Unborrow<Target = impl MosiPin<T>>,
miso: impl Unborrow<Target = impl MisoPin<T>>,
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cs: impl Unborrow<Target = impl CsPin<T>>,
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config: Config,
) -> Self {
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unborrow!(inner, clk, mosi, miso, cs);
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unsafe {
let p = inner.regs();
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let (presc, postdiv) = calc_prescs(config.frequency);
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p.cpsr().write(|w| w.set_cpsdvsr(presc));
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p.cr0().write(|w| {
w.set_dss(0b0111); // 8bit
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w.set_spo(config.polarity == ehnb::Polarity::IdleHigh);
w.set_sph(config.phase == ehnb::Phase::CaptureOnSecondTransition);
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w.set_scr(postdiv);
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});
p.cr1().write(|w| {
w.set_sse(true); // enable
});
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if let Some(pin) = clk.pin_mut() {
pin.io().ctrl().write(|w| w.set_funcsel(1));
}
if let Some(pin) = mosi.pin_mut() {
pin.io().ctrl().write(|w| w.set_funcsel(1));
}
if let Some(pin) = miso.pin_mut() {
pin.io().ctrl().write(|w| w.set_funcsel(1));
}
if let Some(pin) = cs.pin_mut() {
pin.io().ctrl().write(|w| w.set_funcsel(1));
}
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}
Self {
inner,
phantom: PhantomData,
}
}
pub fn write(&mut self, data: &[u8]) {
unsafe {
let p = self.inner.regs();
for &b in data {
while !p.sr().read().tnf() {}
p.dr().write(|w| w.set_data(b as _));
while !p.sr().read().rne() {}
let _ = p.dr().read();
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}
self.flush();
}
}
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pub fn transfer(&mut self, data: &mut [u8]) {
unsafe {
let p = self.inner.regs();
for b in data {
while !p.sr().read().tnf() {}
p.dr().write(|w| w.set_data(*b as _));
while !p.sr().read().rne() {}
*b = p.dr().read().data() as u8;
}
self.flush();
}
}
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pub fn flush(&mut self) {
unsafe {
let p = self.inner.regs();
while p.sr().read().bsy() {}
}
}
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pub fn set_frequency(&mut self, freq: u32) {
let (presc, postdiv) = calc_prescs(freq);
let p = self.inner.regs();
unsafe {
// disable
p.cr1().write(|w| w.set_sse(false));
// change stuff
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p.cpsr().write(|w| w.set_cpsdvsr(presc));
p.cr0().modify(|w| {
w.set_scr(postdiv);
});
// enable
p.cr1().write(|w| w.set_sse(true));
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}
}
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}
impl<'d, T: Instance> eh::Write<u8> for Spi<'d, T> {
type Error = core::convert::Infallible;
fn write(&mut self, words: &[u8]) -> Result<(), Self::Error> {
self.write(words);
Ok(())
}
}
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impl<'d, T: Instance> eh::Transfer<u8> for Spi<'d, T> {
type Error = core::convert::Infallible;
fn transfer<'w>(&mut self, words: &'w mut [u8]) -> Result<&'w [u8], Self::Error> {
self.transfer(words);
Ok(words)
}
}
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mod sealed {
use super::*;
pub trait Instance {
fn regs(&self) -> pac::spi::Spi;
}
pub trait ClkPin<T: Instance> {}
pub trait CsPin<T: Instance> {}
pub trait MosiPin<T: Instance> {}
pub trait MisoPin<T: Instance> {}
}
pub trait Instance: sealed::Instance {}
macro_rules! impl_instance {
($type:ident, $irq:ident) => {
impl sealed::Instance for peripherals::$type {
fn regs(&self) -> pac::spi::Spi {
pac::$type
}
}
impl Instance for peripherals::$type {}
};
}
impl_instance!(SPI0, Spi0);
impl_instance!(SPI1, Spi1);
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pub trait ClkPin<T: Instance>: sealed::ClkPin<T> + OptionalPin {}
pub trait CsPin<T: Instance>: sealed::CsPin<T> + OptionalPin {}
pub trait MosiPin<T: Instance>: sealed::MosiPin<T> + OptionalPin {}
pub trait MisoPin<T: Instance>: sealed::MisoPin<T> + OptionalPin {}
impl<T: Instance> sealed::ClkPin<T> for NoPin {}
impl<T: Instance> ClkPin<T> for NoPin {}
impl<T: Instance> sealed::CsPin<T> for NoPin {}
impl<T: Instance> CsPin<T> for NoPin {}
impl<T: Instance> sealed::MosiPin<T> for NoPin {}
impl<T: Instance> MosiPin<T> for NoPin {}
impl<T: Instance> sealed::MisoPin<T> for NoPin {}
impl<T: Instance> MisoPin<T> for NoPin {}
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macro_rules! impl_pin {
($pin:ident, $instance:ident, $function:ident) => {
impl sealed::$function<peripherals::$instance> for peripherals::$pin {}
impl $function<peripherals::$instance> for peripherals::$pin {}
};
}
impl_pin!(PIN_0, SPI0, MisoPin);
impl_pin!(PIN_1, SPI0, CsPin);
impl_pin!(PIN_2, SPI0, ClkPin);
impl_pin!(PIN_3, SPI0, MosiPin);
impl_pin!(PIN_4, SPI0, MisoPin);
impl_pin!(PIN_5, SPI0, CsPin);
impl_pin!(PIN_6, SPI0, ClkPin);
impl_pin!(PIN_7, SPI0, MosiPin);
impl_pin!(PIN_8, SPI1, MisoPin);
impl_pin!(PIN_9, SPI1, CsPin);
impl_pin!(PIN_10, SPI1, ClkPin);
impl_pin!(PIN_11, SPI1, MosiPin);
impl_pin!(PIN_12, SPI1, MisoPin);
impl_pin!(PIN_13, SPI1, CsPin);
impl_pin!(PIN_14, SPI1, ClkPin);
impl_pin!(PIN_15, SPI1, MosiPin);
impl_pin!(PIN_16, SPI0, MisoPin);
impl_pin!(PIN_17, SPI0, CsPin);
impl_pin!(PIN_18, SPI0, ClkPin);
impl_pin!(PIN_19, SPI0, MosiPin);