Merge pull request #5015 from jamesmunns/james/dma-suggestions

[MCXA]: Extend DMA interface

1 files changed, 184 insertions, 0 deletions

diff --git a/examples/mcxa/src/bin/dma_wrap_transfer.rs b/examples/mcxa/src/bin/dma_wrap_transfer.rs
new file mode 100644
index 000000000..acfd29f08
--- /dev/null
+++ b/examples/mcxa/src/bin/dma_wrap_transfer.rs
@@ -0,0 +1,184 @@
+//! DMA wrap transfer example for MCXA276.
+//!
+//! This example demonstrates using DMA with modulo addressing to wrap around
+//! a source buffer, effectively repeating the source data in the destination.
+//!
+//! # Embassy-style features demonstrated:
+//! - `DmaChannel::is_done()` and `clear_done()` helper methods
+//! - No need to pass register block around
+
+#![no_std]
+#![no_main]
+
+use core::fmt::Write as _;
+
+use embassy_executor::Spawner;
+use embassy_mcxa::clocks::config::Div8;
+use embassy_mcxa::dma::DmaChannel;
+use embassy_mcxa::lpuart::{Blocking, Config, Lpuart, LpuartTx};
+use {defmt_rtt as _, embassy_mcxa as hal, panic_probe as _};
+
+// Source buffer: 4 words (16 bytes), aligned to 16 bytes for modulo
+#[repr(align(16))]
+struct AlignedSrc([u32; 4]);
+
+static mut SRC: AlignedSrc = AlignedSrc([0; 4]);
+static mut DST: [u32; 8] = [0; 8];
+
+/// Helper to print a buffer to UART
+fn print_buffer(tx: &mut LpuartTx<'_, Blocking>, buf_ptr: *const u32, len: usize) {
+    write!(tx, "{:?}", unsafe { core::slice::from_raw_parts(buf_ptr, len) }).ok();
+}
+
+#[embassy_executor::main]
+async fn main(_spawner: Spawner) {
+    // Small delay to allow probe-rs to attach after reset
+    for _ in 0..100_000 {
+        cortex_m::asm::nop();
+    }
+
+    let mut cfg = hal::config::Config::default();
+    cfg.clock_cfg.sirc.fro_12m_enabled = true;
+    cfg.clock_cfg.sirc.fro_lf_div = Some(Div8::no_div());
+    let p = hal::init(cfg);
+
+    defmt::info!("DMA wrap transfer example starting...");
+
+    let config = Config {
+        baudrate_bps: 115_200,
+        ..Default::default()
+    };
+
+    let lpuart = Lpuart::new_blocking(p.LPUART2, p.P2_2, p.P2_3, config).unwrap();
+    let (mut tx, _rx) = lpuart.split();
+
+    tx.blocking_write(b"EDMA wrap transfer example begin.\r\n\r\n").unwrap();
+
+    // Initialize buffers
+    unsafe {
+        SRC.0 = [1, 2, 3, 4];
+        DST = [0; 8];
+    }
+
+    tx.blocking_write(b"Source Buffer:              ").unwrap();
+    print_buffer(&mut tx, unsafe { core::ptr::addr_of!(SRC.0) } as *const u32, 4);
+    tx.blocking_write(b"\r\n").unwrap();
+
+    tx.blocking_write(b"Destination Buffer (before): ").unwrap();
+    print_buffer(&mut tx, core::ptr::addr_of!(DST) as *const u32, 8);
+    tx.blocking_write(b"\r\n").unwrap();
+
+    tx.blocking_write(b"Configuring DMA with Embassy-style API...\r\n")
+        .unwrap();
+
+    // Create DMA channel using Embassy-style API
+    let dma_ch0 = DmaChannel::new(p.DMA_CH0);
+
+    // Configure wrap transfer using direct TCD access:
+    // SRC is 16 bytes (4 * u32). We want to transfer 32 bytes (8 * u32).
+    // SRC modulo is 16 bytes (2^4 = 16) - wraps source address.
+    // DST modulo is 0 (disabled).
+    // This causes the source address to wrap around after 16 bytes,
+    // effectively repeating the source data.
+    unsafe {
+        let t = dma_ch0.tcd();
+
+        // Reset channel state
+        t.ch_csr().write(|w| {
+            w.erq()
+                .disable()
+                .earq()
+                .disable()
+                .eei()
+                .no_error()
+                .ebw()
+                .disable()
+                .done()
+                .clear_bit_by_one()
+        });
+        t.ch_es().write(|w| w.bits(0));
+        t.ch_int().write(|w| w.int().clear_bit_by_one());
+
+        // Source/destination addresses
+        t.tcd_saddr()
+            .write(|w| w.saddr().bits(core::ptr::addr_of!(SRC.0) as u32));
+        t.tcd_daddr()
+            .write(|w| w.daddr().bits(core::ptr::addr_of_mut!(DST) as u32));
+
+        // Offsets: both increment by 4 bytes
+        t.tcd_soff().write(|w| w.soff().bits(4));
+        t.tcd_doff().write(|w| w.doff().bits(4));
+
+        // Attributes: 32-bit transfers (size = 2)
+        // SMOD = 4 (2^4 = 16 byte modulo for source), DMOD = 0 (disabled)
+        t.tcd_attr().write(|w| {
+            w.ssize()
+                .bits(2)
+                .dsize()
+                .bits(2)
+                .smod()
+                .bits(4) // Source modulo: 2^4 = 16 bytes
+                .dmod()
+                .bits(0) // Dest modulo: disabled
+        });
+
+        // Transfer 32 bytes total in one minor loop
+        let nbytes = 32u32;
+        t.tcd_nbytes_mloffno().write(|w| w.nbytes().bits(nbytes));
+
+        // Source wraps via modulo, no adjustment needed
+        t.tcd_slast_sda().write(|w| w.slast_sda().bits(0));
+        // Reset dest address after major loop
+        t.tcd_dlast_sga().write(|w| w.dlast_sga().bits(-(nbytes as i32) as u32));
+
+        // Major loop count = 1
+        t.tcd_biter_elinkno().write(|w| w.biter().bits(1));
+        t.tcd_citer_elinkno().write(|w| w.citer().bits(1));
+
+        // Enable interrupt on major loop completion
+        t.tcd_csr().write(|w| w.intmajor().set_bit());
+
+        cortex_m::asm::dsb();
+
+        tx.blocking_write(b"Triggering transfer...\r\n").unwrap();
+        dma_ch0.trigger_start();
+    }
+
+    // Wait for completion using channel helper method
+    while !dma_ch0.is_done() {
+        cortex_m::asm::nop();
+    }
+    unsafe {
+        dma_ch0.clear_done();
+    }
+
+    tx.blocking_write(b"\r\nEDMA wrap transfer example finish.\r\n\r\n")
+        .unwrap();
+    tx.blocking_write(b"Destination Buffer (after):  ").unwrap();
+    print_buffer(&mut tx, core::ptr::addr_of!(DST) as *const u32, 8);
+    tx.blocking_write(b"\r\n\r\n").unwrap();
+
+    // Verify: DST should be [1, 2, 3, 4, 1, 2, 3, 4]
+    let expected = [1u32, 2, 3, 4, 1, 2, 3, 4];
+    let mut mismatch = false;
+    unsafe {
+        for i in 0..8 {
+            if DST[i] != expected[i] {
+                mismatch = true;
+                break;
+            }
+        }
+    }
+
+    if mismatch {
+        tx.blocking_write(b"FAIL: Mismatch detected!\r\n").unwrap();
+        defmt::error!("FAIL: Mismatch detected!");
+    } else {
+        tx.blocking_write(b"PASS: Data verified.\r\n").unwrap();
+        defmt::info!("PASS: Data verified.");
+    }
+
+    loop {
+        cortex_m::asm::wfe();
+    }
+}