1 files changed, 185 insertions, 0 deletions

diff --git a/cyw43-pio/src/lib.rs b/cyw43-pio/src/lib.rs
new file mode 100644
index 000000000..2159796cd
--- /dev/null
+++ b/cyw43-pio/src/lib.rs
@@ -0,0 +1,185 @@
+#![no_std]
+#![allow(incomplete_features)]
+#![feature(async_fn_in_trait)]
+
+use core::slice;
+
+use cyw43::SpiBusCyw43;
+use embassy_rp::dma::Channel;
+use embassy_rp::gpio::{Drive, Output, Pin, Pull, SlewRate};
+use embassy_rp::pio::{PioStateMachine, ShiftDirection};
+use embassy_rp::relocate::RelocatedProgram;
+use embassy_rp::{pio_instr_util, Peripheral};
+use pio::Wrap;
+use pio_proc::pio_asm;
+
+pub struct PioSpi<CS: Pin, SM, DMA> {
+    cs: Output<'static, CS>,
+    sm: SM,
+    dma: DMA,
+    wrap_target: u8,
+}
+
+impl<CS, SM, DMA> PioSpi<CS, SM, DMA>
+where
+    SM: PioStateMachine,
+    DMA: Channel,
+    CS: Pin,
+{
+    pub fn new<DIO, CLK>(mut sm: SM, cs: Output<'static, CS>, dio: DIO, clk: CLK, dma: DMA) -> Self
+    where
+        DIO: Pin,
+        CLK: Pin,
+    {
+        let program = pio_asm!(
+            ".side_set 1"
+            // "set pindirs, 1 side 0"
+            // "set pins, 0    side 0"
+            ".wrap_target"
+            "lp:",
+            "out pins, 1    side 0"
+            "jmp x-- lp     side 1"
+            "set pindirs, 0 side 0"
+            "nop            side 1"
+            "lp2:"
+            "in pins, 1     side 1"
+            "jmp y-- lp2    side 0"
+
+            "wait 1 pin 0   side 0"
+            "irq 0          side 0"
+
+            ".wrap"
+        );
+
+        let relocated = RelocatedProgram::new(&program.program);
+
+        let mut pin_io = sm.make_pio_pin(dio);
+        pin_io.set_pull(Pull::Down);
+        pin_io.set_schmitt(true);
+        pin_io.set_input_sync_bypass(true);
+
+        let mut pin_clk = sm.make_pio_pin(clk);
+        pin_clk.set_drive_strength(Drive::_12mA);
+        pin_clk.set_slew_rate(SlewRate::Fast);
+
+        sm.write_instr(relocated.origin() as usize, relocated.code());
+
+        // 32 Mhz
+        sm.set_clkdiv(0x03E8);
+
+        // 16 Mhz
+        // sm.set_clkdiv(0x07d0);
+
+        // 8Mhz
+        // sm.set_clkdiv(0x0a_00);
+
+        // 1Mhz
+        // sm.set_clkdiv(0x7d_00);
+
+        // slowest possible
+        // sm.set_clkdiv(0xffff_00);
+
+        sm.set_autopull(true);
+        // sm.set_pull_threshold(32);
+        sm.set_autopush(true);
+        // sm.set_push_threshold(32);
+
+        sm.set_out_pins(&[&pin_io]);
+        sm.set_in_base_pin(&pin_io);
+
+        sm.set_set_pins(&[&pin_clk]);
+        pio_instr_util::set_pindir(&mut sm, 0b1);
+        sm.set_set_pins(&[&pin_io]);
+        pio_instr_util::set_pindir(&mut sm, 0b1);
+
+        sm.set_sideset_base_pin(&pin_clk);
+        sm.set_sideset_count(1);
+
+        sm.set_out_shift_dir(ShiftDirection::Left);
+        sm.set_in_shift_dir(ShiftDirection::Left);
+
+        let Wrap { source, target } = relocated.wrap();
+        sm.set_wrap(source, target);
+
+        // pull low for startup
+        pio_instr_util::set_pin(&mut sm, 0);
+
+        Self {
+            cs,
+            sm,
+            dma,
+            wrap_target: target,
+        }
+    }
+
+    pub async fn write(&mut self, write: &[u32]) -> u32 {
+        self.sm.set_enable(false);
+        let write_bits = write.len() * 32 - 1;
+        let read_bits = 31;
+
+        defmt::trace!("write={} read={}", write_bits, read_bits);
+
+        let mut dma = Peripheral::into_ref(&mut self.dma);
+        pio_instr_util::set_x(&mut self.sm, write_bits as u32);
+        pio_instr_util::set_y(&mut self.sm, read_bits as u32);
+        pio_instr_util::set_pindir(&mut self.sm, 0b1);
+        pio_instr_util::exec_jmp(&mut self.sm, self.wrap_target);
+
+        self.sm.set_enable(true);
+
+        self.sm.dma_push(dma.reborrow(), write).await;
+
+        let mut status = 0;
+        self.sm.dma_pull(dma.reborrow(), slice::from_mut(&mut status)).await;
+        status
+    }
+
+    pub async fn cmd_read(&mut self, cmd: u32, read: &mut [u32]) -> u32 {
+        self.sm.set_enable(false);
+        let write_bits = 31;
+        let read_bits = read.len() * 32 + 32 - 1;
+
+        defmt::trace!("write={} read={}", write_bits, read_bits);
+
+        let mut dma = Peripheral::into_ref(&mut self.dma);
+        pio_instr_util::set_y(&mut self.sm, read_bits as u32);
+        pio_instr_util::set_x(&mut self.sm, write_bits as u32);
+        pio_instr_util::set_pindir(&mut self.sm, 0b1);
+        pio_instr_util::exec_jmp(&mut self.sm, self.wrap_target);
+        // self.cs.set_low();
+        self.sm.set_enable(true);
+
+        self.sm.dma_push(dma.reborrow(), slice::from_ref(&cmd)).await;
+        self.sm.dma_pull(dma.reborrow(), read).await;
+
+        let mut status = 0;
+        self.sm.dma_pull(dma.reborrow(), slice::from_mut(&mut status)).await;
+        status
+    }
+}
+
+impl<CS, SM, DMA> SpiBusCyw43 for PioSpi<CS, SM, DMA>
+where
+    CS: Pin,
+    SM: PioStateMachine,
+    DMA: Channel,
+{
+    async fn cmd_write(&mut self, write: &[u32]) -> u32 {
+        self.cs.set_low();
+        let status = self.write(write).await;
+        self.cs.set_high();
+        status
+    }
+
+    async fn cmd_read(&mut self, write: u32, read: &mut [u32]) -> u32 {
+        self.cs.set_low();
+        let status = self.cmd_read(write, read).await;
+        self.cs.set_high();
+        status
+    }
+
+    async fn wait_for_event(&mut self) {
+        self.sm.wait_irq(0).await;
+        self.sm.clear_irq(0);
+    }
+}