1 files changed, 278 insertions, 0 deletions

diff --git a/examples/mcxa/src/bin/raw_dma_channel_link.rs b/examples/mcxa/src/bin/raw_dma_channel_link.rs
new file mode 100644
index 000000000..74785e4f3
--- /dev/null
+++ b/examples/mcxa/src/bin/raw_dma_channel_link.rs
@@ -0,0 +1,278 @@
+//! DMA channel linking example for MCXA276.
+//!
+//! NOTE: this is a "raw dma" example! It exists as a proof of concept, as we don't have
+//! a high-level and safe API for. It should not be taken as typical, recommended, or
+//! stable usage!
+//!
+//! This example demonstrates DMA channel linking (minor and major loop linking):
+//! - Channel 0: Transfers SRC_BUFFER to DEST_BUFFER0, with:
+//!   - Minor Link to Channel 1 (triggers CH1 after each minor loop)
+//!   - Major Link to Channel 2 (triggers CH2 after major loop completes)
+//! - Channel 1: Transfers SRC_BUFFER to DEST_BUFFER1 (triggered by CH0 minor link)
+//! - Channel 2: Transfers SRC_BUFFER to DEST_BUFFER2 (triggered by CH0 major link)
+//!
+//! # Embassy-style features demonstrated:
+//! - `DmaChannel::new()` for channel creation
+//! - `DmaChannel::is_done()` and `clear_done()` helper methods
+//! - Channel linking with `set_minor_link()` and `set_major_link()`
+
+#![no_std]
+#![no_main]
+
+use embassy_executor::Spawner;
+use embassy_mcxa::clocks::config::Div8;
+use embassy_mcxa::dma::DmaChannel;
+use embassy_mcxa::pac;
+use static_cell::ConstStaticCell;
+use {defmt_rtt as _, embassy_mcxa as hal, panic_probe as _};
+
+// Buffers
+static SRC_BUFFER: ConstStaticCell<[u32; 4]> = ConstStaticCell::new([1, 2, 3, 4]);
+static DEST_BUFFER0: ConstStaticCell<[u32; 4]> = ConstStaticCell::new([0; 4]);
+static DEST_BUFFER1: ConstStaticCell<[u32; 4]> = ConstStaticCell::new([0; 4]);
+static DEST_BUFFER2: ConstStaticCell<[u32; 4]> = ConstStaticCell::new([0; 4]);
+
+#[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 channel link example starting...");
+
+    // DMA is initialized during hal::init() - no need to call ensure_init()
+
+    let pac_periphs = unsafe { pac::Peripherals::steal() };
+    let dma0 = &pac_periphs.dma0;
+    let edma = unsafe { &*pac::Edma0Tcd0::ptr() };
+
+    // Clear any residual state
+    for i in 0..3 {
+        let t = edma.tcd(i);
+        t.ch_csr().write(|w| w.erq().disable().done().clear_bit_by_one());
+        t.ch_int().write(|w| w.int().clear_bit_by_one());
+        t.ch_es().write(|w| w.err().clear_bit_by_one());
+        t.ch_mux().write(|w| unsafe { w.bits(0) });
+    }
+
+    // Clear Global Halt/Error state
+    dma0.mp_csr().modify(|_, w| {
+        w.halt()
+            .normal_operation()
+            .hae()
+            .normal_operation()
+            .ecx()
+            .normal_operation()
+            .cx()
+            .normal_operation()
+    });
+
+    defmt::info!("EDMA channel link example begin.");
+
+    // Initialize buffers
+    let src = SRC_BUFFER.take();
+    let dst0 = DEST_BUFFER0.take();
+    let dst1 = DEST_BUFFER1.take();
+    let dst2 = DEST_BUFFER2.take();
+
+    defmt::info!("Source Buffer: {=[?]}", src.as_slice());
+    defmt::info!("DEST0 (before): {=[?]}", dst0.as_slice());
+    defmt::info!("DEST1 (before): {=[?]}", dst1.as_slice());
+    defmt::info!("DEST2 (before): {=[?]}", dst2.as_slice());
+
+    defmt::info!("Configuring DMA channels with Embassy-style API...");
+
+    let ch0 = DmaChannel::new(p.DMA_CH0);
+    let ch1 = DmaChannel::new(p.DMA_CH1);
+    let ch2 = DmaChannel::new(p.DMA_CH2);
+
+    // Configure channels using direct TCD access (advanced feature demo)
+    // This example demonstrates channel linking which requires direct TCD manipulation
+
+    // Helper to configure TCD for memory-to-memory transfer
+    // Parameters: channel, src, dst, width, nbytes (minor loop), count (major loop), interrupt
+    #[allow(clippy::too_many_arguments)]
+    unsafe fn configure_tcd(
+        edma: &embassy_mcxa::pac::edma_0_tcd0::RegisterBlock,
+        ch: usize,
+        src: u32,
+        dst: u32,
+        width: u8,
+        nbytes: u32,
+        count: u16,
+        enable_int: bool,
+    ) {
+        let t = edma.tcd(ch);
+
+        // 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(src));
+        t.tcd_daddr().write(|w| w.daddr().bits(dst));
+
+        // Offsets: increment by width
+        t.tcd_soff().write(|w| w.soff().bits(width as u16));
+        t.tcd_doff().write(|w| w.doff().bits(width as u16));
+
+        // Attributes: size = log2(width)
+        let size = match width {
+            1 => 0,
+            2 => 1,
+            4 => 2,
+            _ => 0,
+        };
+        t.tcd_attr().write(|w| w.ssize().bits(size).dsize().bits(size));
+
+        // Number of bytes per minor loop
+        t.tcd_nbytes_mloffno().write(|w| w.nbytes().bits(nbytes));
+
+        // Major loop: reset source address after major loop
+        let total_bytes = nbytes * count as u32;
+        t.tcd_slast_sda()
+            .write(|w| w.slast_sda().bits(-(total_bytes as i32) as u32));
+        t.tcd_dlast_sga()
+            .write(|w| w.dlast_sga().bits(-(total_bytes as i32) as u32));
+
+        // Major loop count
+        t.tcd_biter_elinkno().write(|w| w.biter().bits(count));
+        t.tcd_citer_elinkno().write(|w| w.citer().bits(count));
+
+        // Control/status: enable interrupt if requested
+        if enable_int {
+            t.tcd_csr().write(|w| w.intmajor().set_bit());
+        } else {
+            t.tcd_csr().write(|w| w.intmajor().clear_bit());
+        }
+
+        cortex_m::asm::dsb();
+    }
+
+    unsafe {
+        // Channel 0: Transfer 16 bytes total (8 bytes per minor loop, 2 major iterations)
+        // Minor Link -> Channel 1
+        // Major Link -> Channel 2
+        configure_tcd(
+            edma,
+            0,
+            src.as_ptr() as u32,
+            dst0.as_mut_ptr() as u32,
+            4,     // src width
+            8,     // nbytes (minor loop = 2 words)
+            2,     // count (major loop = 2 iterations)
+            false, // no interrupt
+        );
+        ch0.set_minor_link(1); // Link to CH1 after each minor loop
+        ch0.set_major_link(2); // Link to CH2 after major loop
+
+        // Channel 1: Transfer 16 bytes (triggered by CH0 minor link)
+        configure_tcd(
+            edma,
+            1,
+            src.as_ptr() as u32,
+            dst1.as_mut_ptr() as u32,
+            4,
+            16, // full buffer in one minor loop
+            1,  // 1 major iteration
+            false,
+        );
+
+        // Channel 2: Transfer 16 bytes (triggered by CH0 major link)
+        configure_tcd(
+            edma,
+            2,
+            src.as_ptr() as u32,
+            dst2.as_mut_ptr() as u32,
+            4,
+            16,   // full buffer in one minor loop
+            1,    // 1 major iteration
+            true, // enable interrupt
+        );
+    }
+
+    defmt::info!("Triggering Channel 0 (1st minor loop)...");
+
+    // Trigger first minor loop of CH0
+    unsafe {
+        ch0.trigger_start();
+    }
+
+    // Wait for CH1 to complete (triggered by CH0 minor link)
+    while !ch1.is_done() {
+        cortex_m::asm::nop();
+    }
+    unsafe {
+        ch1.clear_done();
+    }
+
+    defmt::info!("CH1 done (via minor link).");
+    defmt::info!("Triggering Channel 0 (2nd minor loop)...");
+
+    // Trigger second minor loop of CH0
+    unsafe {
+        ch0.trigger_start();
+    }
+
+    // Wait for CH0 major loop to complete
+    while !ch0.is_done() {
+        cortex_m::asm::nop();
+    }
+    unsafe {
+        ch0.clear_done();
+    }
+
+    defmt::info!("CH0 major loop done.");
+
+    // Wait for CH2 to complete (triggered by CH0 major link)
+    // Using is_done() instead of AtomicBool - the standard interrupt handler
+    // clears the interrupt flag and wakes wakers, but DONE bit remains set
+    while !ch2.is_done() {
+        cortex_m::asm::nop();
+    }
+    unsafe {
+        ch2.clear_done();
+    }
+
+    defmt::info!("CH2 done (via major link).");
+
+    defmt::info!("EDMA channel link example finish.");
+
+    defmt::info!("DEST0 (after): {=[?]}", dst0.as_slice());
+    defmt::info!("DEST1 (after): {=[?]}", dst1.as_slice());
+    defmt::info!("DEST2 (after): {=[?]}", dst2.as_slice());
+
+    // Verify all buffers match source
+    let mut success = true;
+    for sli in [dst0, dst1, dst2] {
+        success &= sli == src;
+    }
+
+    if success {
+        defmt::info!("PASS: Data verified.");
+    } else {
+        defmt::error!("FAIL: Mismatch detected!");
+    }
+
+    loop {
+        cortex_m::asm::wfe();
+    }
+}