Add option to configure the device driver IRAM placement (RFC) (#1096)

* SPI RAM patch

* SPI in IRAM

* Add DMA functions to IRAM

* Try fixing the interrupt latency issue

* Revert changes

* Rename the option name to `optimize-spi-in-iram`

* Fix clippy warning

* Fix typo

CHANGELOG.md

@@ -74,6 +74,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - ESP32-S3: Added support for 80Mhz PSRAM (#1069)
 - ESP32-C3/S3: Add workaround for USB pin exchange on usb-serial-jtag (#1104).
 - ESP32C6: Added LP_UART initialization (#1113)
+- Add `place-spi-driver-in-ram` feature to `esp-hal-common` (#1096)
+
 ### Changed
 
 - Set up interrupts for the DMA and async enabled peripherals only when `async` feature is provided (#1042)

esp-hal/Cargo.toml

@@ -158,6 +158,9 @@ rv-init-data     = ["esp-riscv-rt/init-data", "esp-riscv-rt/init-rw-text"]
 rv-zero-rtc-bss  = ["esp-riscv-rt/zero-rtc-fast-bss"]
 rv-init-rtc-data = ["esp-riscv-rt/init-rtc-fast-data", "esp-riscv-rt/init-rtc-fast-text"]
 
+# Configuration for placing device drivers in the IRAM for faster access
+place-spi-driver-in-ram = []
+
 # Enable the `impl-register-debug` feature for the selected PAC
 debug = [
     "esp32?/impl-register-debug",

esp-hal/src/spi/master.rs

@@ -50,6 +50,8 @@
 use core::marker::PhantomData;
 
 use fugit::HertzU32;
+#[cfg(feature = "place-spi-driver-in-ram")]
+use procmacros::ram;
 
 use super::{
     DuplexMode,
@@ -1027,6 +1029,7 @@ pub mod dma {
         /// This will return a [SpiDmaTransfer] owning the buffer(s) and the SPI
         /// instance. The maximum amount of data to be sent is 32736
         /// bytes.
+        #[cfg_attr(feature = "place-spi-driver-in-ram", ram)]
         pub fn dma_write<TXBUF>(
             mut self,
             words: TXBUF,
@@ -1053,6 +1056,7 @@ pub mod dma {
         /// This will return a [SpiDmaTransfer] owning the buffer(s) and the SPI
         /// instance. The maximum amount of data to be received is 32736
         /// bytes.
+        #[cfg_attr(feature = "place-spi-driver-in-ram", ram)]
         pub fn dma_read<RXBUF>(
             mut self,
             mut words: RXBUF,
@@ -1119,6 +1123,7 @@ pub mod dma {
         C::P: SpiPeripheral,
         M: IsHalfDuplex,
     {
+        #[cfg_attr(feature = "place-spi-driver-in-ram", ram)]
         pub fn read<RXBUF>(
             mut self,
             data_mode: SpiDataMode,
@@ -1192,6 +1197,7 @@ pub mod dma {
             })
         }
 
+        #[cfg_attr(feature = "place-spi-driver-in-ram", ram)]
         pub fn write<TXBUF>(
             mut self,
             data_mode: SpiDataMode,
@@ -1837,6 +1843,7 @@ where
         Ok(words)
     }
 
+    #[cfg_attr(feature = "place-spi-driver-in-ram", ram)]
     fn start_write_bytes_dma(
         &mut self,
         ptr: *const u8,
@@ -1867,6 +1874,7 @@ where
         Ok(())
     }
 
+    #[cfg_attr(feature = "place-spi-driver-in-ram", ram)]
     fn start_read_bytes_dma(
         &mut self,
         ptr: *mut u8,
@@ -2518,6 +2526,7 @@ pub trait Instance {
     /// you must ensure that the whole messages was written correctly, use
     /// [`Self::flush`].
     // FIXME: See below.
+    #[cfg_attr(feature = "place-spi-driver-in-ram", ram)]
     fn write_bytes(&mut self, words: &[u8]) -> Result<(), Error> {
         let num_chunks = words.len() / FIFO_SIZE;
 
@@ -2578,6 +2587,7 @@ pub trait Instance {
     /// Sends out a stuffing byte for every byte to read. This function doesn't
     /// perform flushing. If you want to read the response to something you
     /// have written before, consider using [`Self::transfer`] instead.
+    #[cfg_attr(feature = "place-spi-driver-in-ram", ram)]
     fn read_bytes(&mut self, words: &mut [u8]) -> Result<(), Error> {
         let empty_array = [EMPTY_WRITE_PAD; FIFO_SIZE];
 
@@ -2598,6 +2608,7 @@ pub trait Instance {
     // FIXME: Using something like `core::slice::from_raw_parts` and
     // `copy_from_slice` on the receive registers works only for the esp32 and
     // esp32c3 varaints. The reason for this is unknown.
+    #[cfg_attr(feature = "place-spi-driver-in-ram", ram)]
     fn read_bytes_from_fifo(&mut self, words: &mut [u8]) -> Result<(), Error> {
         let reg_block = self.register_block();
 
@@ -2634,6 +2645,7 @@ pub trait Instance {
         Ok(())
     }
 
+    #[cfg_attr(feature = "place-spi-driver-in-ram", ram)]
     fn transfer<'w>(&mut self, words: &'w mut [u8]) -> Result<&'w [u8], Error> {
         for chunk in words.chunks_mut(FIFO_SIZE) {
             self.write_bytes(chunk)?;