Merge #951

951: (embassy-rp): Implementation of generic flash mutation access r=Dirbaio a=MathiasKoch

I have attempted to utilize the work done in `rp2040-flash` by implementing `embedded-storage` traits on top, for RP2040.

Concerns:
1. ~~Should the DMA be paused where I have put a FIXME note? `DMA_CHx.ctrl_trig().write(|w| { w.set_en(false) })`? If so, how to properly do that without have control over the peripheral for the DMA channels? And if so, I assume we should only re-enable/unpause the ones that were enabled before?~~
2. ~~Should I make sure core2 is halted as part of this code? I am not sure if https://github.com/jannic/rp2040-flash/blob/ea8ab1ac807a7ab2b28a18bb5ca2e42495bb744d/examples/flash_example.rs#L103-L109 is heavy/slow code to run?~~
3. ~~Any good way of making this configurable over `FLASH_SIZE`, `WRITE_SIZE` and `ERASE_SIZE` without doing it as generics or parameters, as those make it possible to do differing configs throughout the same program, which feels wrong? Preferably, a compile-time option?~~


**EDIT:**
I have implemented the flash API here under the assumption that all external QSPI nor flashes are infact `Multiwrite` capable, as this makes it possible to use the ROM function for writes of 1 bytes at a time.

I have also added a HIL test for this, but because HIL tests are running 100% from RAM and I wanted to make sure it still works when running from flash, I have also added an example testing erase/write cycles of entire sectors, as well as single bytes in multi-write style.

Ping `@Dirbaio` 

Co-authored-by: Mathias <[email protected]>
Co-authored-by: Vincent Stakenburg <[email protected]>
Co-authored-by: Joakim Hulthe <[email protected]>
Co-authored-by: Alex Martens <[email protected]>
Co-authored-by: Ulf Lilleengen <[email protected]>
Co-authored-by: Dario Nieuwenhuis <[email protected]>

2 files changed, 90 insertions, 0 deletions

diff --git a/examples/rp/Cargo.toml b/examples/rp/Cargo.toml
index ec9896b77..31f688305 100644
--- a/examples/rp/Cargo.toml
+++ b/examples/rp/Cargo.toml
@@ -30,6 +30,7 @@ byte-slice-cast = { version = "1.2.0", default-features = false }
 embedded-hal-1 = { package = "embedded-hal", version = "=1.0.0-alpha.9" }
 embedded-hal-async = { version = "0.1.0-alpha.3" }
 embedded-io = { version = "0.3.1", features = ["async", "defmt"] }
+embedded-storage = { version = "0.3" }
 static_cell = "1.0.0"
 
 [profile.release]
diff --git a/examples/rp/src/bin/flash.rs b/examples/rp/src/bin/flash.rs
new file mode 100644
index 000000000..8d6b379f4
--- /dev/null
+++ b/examples/rp/src/bin/flash.rs
@@ -0,0 +1,89 @@
+#![no_std]
+#![no_main]
+#![feature(type_alias_impl_trait)]
+
+use defmt::*;
+use embassy_executor::Spawner;
+use embassy_rp::flash::{ERASE_SIZE, FLASH_BASE};
+use embassy_rp::peripherals::FLASH;
+use embassy_time::{Duration, Timer};
+use {defmt_rtt as _, panic_probe as _};
+
+const ADDR_OFFSET: u32 = 0x100000;
+const FLASH_SIZE: usize = 2 * 1024 * 1024;
+
+#[embassy_executor::main]
+async fn main(_spawner: Spawner) {
+    let p = embassy_rp::init(Default::default());
+    info!("Hello World!");
+
+    // add some delay to give an attached debug probe time to parse the
+    // defmt RTT header. Reading that header might touch flash memory, which
+    // interferes with flash write operations.
+    // https://github.com/knurling-rs/defmt/pull/683
+    Timer::after(Duration::from_millis(10)).await;
+
+    let mut flash = embassy_rp::flash::Flash::<_, FLASH_SIZE>::new(p.FLASH);
+    erase_write_sector(&mut flash, 0x00);
+
+    multiwrite_bytes(&mut flash, ERASE_SIZE as u32);
+
+    loop {}
+}
+
+fn multiwrite_bytes(flash: &mut embassy_rp::flash::Flash<'_, FLASH, FLASH_SIZE>, offset: u32) {
+    info!(">>>> [multiwrite_bytes]");
+    let mut read_buf = [0u8; ERASE_SIZE];
+    defmt::unwrap!(flash.read(ADDR_OFFSET + offset, &mut read_buf));
+
+    info!("Addr of flash block is {:x}", ADDR_OFFSET + offset + FLASH_BASE as u32);
+    info!("Contents start with {=[u8]}", read_buf[0..4]);
+
+    defmt::unwrap!(flash.erase(ADDR_OFFSET + offset, ADDR_OFFSET + offset + ERASE_SIZE as u32));
+
+    defmt::unwrap!(flash.read(ADDR_OFFSET + offset, &mut read_buf));
+    info!("Contents after erase starts with {=[u8]}", read_buf[0..4]);
+    if read_buf.iter().any(|x| *x != 0xFF) {
+        defmt::panic!("unexpected");
+    }
+
+    defmt::unwrap!(flash.write(ADDR_OFFSET + offset, &[0x01]));
+    defmt::unwrap!(flash.write(ADDR_OFFSET + offset + 1, &[0x02]));
+    defmt::unwrap!(flash.write(ADDR_OFFSET + offset + 2, &[0x03]));
+    defmt::unwrap!(flash.write(ADDR_OFFSET + offset + 3, &[0x04]));
+
+    defmt::unwrap!(flash.read(ADDR_OFFSET + offset, &mut read_buf));
+    info!("Contents after write starts with {=[u8]}", read_buf[0..4]);
+    if &read_buf[0..4] != &[0x01, 0x02, 0x03, 0x04] {
+        defmt::panic!("unexpected");
+    }
+}
+
+fn erase_write_sector(flash: &mut embassy_rp::flash::Flash<'_, FLASH, FLASH_SIZE>, offset: u32) {
+    info!(">>>> [erase_write_sector]");
+    let mut buf = [0u8; ERASE_SIZE];
+    defmt::unwrap!(flash.read(ADDR_OFFSET + offset, &mut buf));
+
+    info!("Addr of flash block is {:x}", ADDR_OFFSET + offset + FLASH_BASE as u32);
+    info!("Contents start with {=[u8]}", buf[0..4]);
+
+    defmt::unwrap!(flash.erase(ADDR_OFFSET + offset, ADDR_OFFSET + offset + ERASE_SIZE as u32));
+
+    defmt::unwrap!(flash.read(ADDR_OFFSET + offset, &mut buf));
+    info!("Contents after erase starts with {=[u8]}", buf[0..4]);
+    if buf.iter().any(|x| *x != 0xFF) {
+        defmt::panic!("unexpected");
+    }
+
+    for b in buf.iter_mut() {
+        *b = 0xDA;
+    }
+
+    defmt::unwrap!(flash.write(ADDR_OFFSET + offset, &buf));
+
+    defmt::unwrap!(flash.read(ADDR_OFFSET + offset, &mut buf));
+    info!("Contents after write starts with {=[u8]}", buf[0..4]);
+    if buf.iter().any(|x| *x != 0xDA) {
+        defmt::panic!("unexpected");
+    }
+}