feat(spi): DMA support (#131)

* initial SPI DMA support

* spi dma: add dma channel update points

* micropython spi test

---------

Co-authored-by: Guy Sviry <[email protected]>

.github/workflows/ci-micropython.yml

@@ -24,6 +24,10 @@ jobs:
         env:
           VERSION: ${{ matrix.micropython_version }}
       - name: Create filesystem
-        run: python test/mklittlefs.py
+        run: python test/mklittlefs.py littlefs.img test/micropython/main.py
       - name: Test Micropython
         run: timeout 10 npm run start:micropython -- --image micropython.uf2 --expect-text "Hello, MicroPython!"
+      - name: Create SPI test filesystem
+        run: python test/mklittlefs.py littlefs-spi.img test/micropython/main-spi.py
+      - name: Test Micropython SPI
+        run: timeout 10 npm run test:micropython-spi -- "hello world" "h" "0123456789abcdef0123456789abcdef0123456789abcdef"

demo/micropython-run.ts

@@ -33,6 +33,7 @@ console.log(`Loading uf2 image ${imageName}`);
 loadUF2(imageName, mcu);
 
 if (fs.existsSync('littlefs.img') && !args.circuitpython) {
+  console.log(`Loading uf2 image littlefs.img`);
   loadMicropythonFlashImage('littlefs.img', mcu);
 } else if (fs.existsSync('fat12.img') && args.circuitpython) {
   loadCircuitpythonFlashImage('fat12.img', mcu);

package.json

@@ -39,7 +39,8 @@
     "start:micropython": "ts-node demo/micropython-run.ts",
     "start:circuitpython": "ts-node demo/micropython-run.ts --circuitpython",
     "start:gdbdiff": "ts-node debug/gdbdiff.ts",
-    "test": "jest"
+    "test": "jest",
+    "test:micropython-spi": "ts-node test/micropython-spi-test.ts"
   },
   "devDependencies": {
     "@types/jest": "^27.4.1",

src/peripherals/spi.ts

@@ -1,5 +1,6 @@
 import { RP2040 } from '../rp2040';
 import { FIFO } from '../utils/fifo';
+import { DREQChannel } from './dma';
 import { BasePeripheral, Peripheral } from './peripheral';
 
 const SSPCR0 = 0x000; // Control register 0, SSPCR0 on page 3-4
@@ -58,6 +59,11 @@ const SSPRXINTR = 1 << 2;
 const SSPRTINTR = 1 << 1;
 const SSPRORINTR = 1 << 0;
 
+export interface ISPIDMAChannels {
+  rx: DREQChannel;
+  tx: DREQChannel;
+}
+
 export class RPSPI extends BasePeripheral implements Peripheral {
   readonly rxFIFO = new FIFO(8);
   readonly txFIFO = new FIFO(8);
@@ -105,8 +111,26 @@ export class RPSPI extends BasePeripheral implements Peripheral {
     return this.rp2040.clkPeri / (this.clockDivisor * (1 + scr));
   }
 
-  constructor(rp2040: RP2040, name: string, readonly irq: number) {
+  private updateDMATx() {
+    if (this.txFIFO.full) {
+      this.rp2040.dma.clearDREQ(this.dreq.tx);
+    } else {
+      this.rp2040.dma.setDREQ(this.dreq.tx);
+    }
+  }
+
+  private updateDMARx() {
+    if (this.rxFIFO.empty) {
+      this.rp2040.dma.clearDREQ(this.dreq.rx);
+    } else {
+      this.rp2040.dma.setDREQ(this.dreq.rx);
+    }
+  }
+
+  constructor(rp2040: RP2040, name: string, readonly irq: number, readonly dreq: ISPIDMAChannels) {
     super(rp2040, name);
+    this.updateDMATx();
+    this.updateDMARx();
   }
 
   private doTX() {
@@ -148,6 +172,9 @@ export class RPSPI extends BasePeripheral implements Peripheral {
     if (this.intStatus !== prevStatus) {
       this.checkInterrupts();
     }
+
+    this.updateDMATx();
+    this.updateDMARx();
   }
 
   readUint32(offset: number) {
@@ -211,7 +238,8 @@ export class RPSPI extends BasePeripheral implements Peripheral {
         return;
       case SSPDR:
         if (!this.txFIFO.full) {
-          this.txFIFO.push(value);
+          // decoded with respect to SSPCR0.DSS
+          this.txFIFO.push(value & ((1 << this.dataBits) - 1));
           this.doTX();
           this.fifosUpdated();
         }

src/rp2040.ts

@@ -69,7 +69,6 @@ export class RP2040 {
     }),
   ];
   readonly i2c = [new RPI2C(this, 'I2C0', IRQ.I2C0), new RPI2C(this, 'I2C1', IRQ.I2C1)];
-  readonly spi = [new RPSPI(this, 'SPI0', IRQ.SPI0), new RPSPI(this, 'SPI1', IRQ.SPI1)];
   readonly pwm = new RPPWM(this, 'PWM_BASE');
   readonly adc = new RPADC(this, 'ADC');
 
@@ -121,6 +120,16 @@ export class RP2040 {
     new RPPIO(this, 'PIO1', IRQ.PIO1_IRQ0, 1),
   ];
   readonly usbCtrl = new RPUSBController(this, 'USB');
+  readonly spi = [
+    new RPSPI(this, 'SPI0', IRQ.SPI0, {
+      rx: DREQChannel.DREQ_SPI0_RX,
+      tx: DREQChannel.DREQ_SPI0_TX,
+    }),
+    new RPSPI(this, 'SPI1', IRQ.SPI1, {
+      rx: DREQChannel.DREQ_SPI1_RX,
+      tx: DREQChannel.DREQ_SPI1_TX,
+    }),
+  ];
 
   private stopped = true;
 

test/micropython-spi-test.ts

@@ -0,0 +1,53 @@
+import { GPIOPinState, RP2040 } from '../src';
+import { ConsoleLogger, LogLevel } from '../src/utils/logging';
+import { bootromB1 } from '../demo/bootrom';
+import { loadUF2, loadMicropythonFlashImage } from '../demo/load-flash';
+import fs from 'fs';
+import minimist from 'minimist';
+
+const args = minimist(process.argv.slice(2));
+
+const mcu = new RP2040();
+mcu.loadBootrom(bootromB1);
+mcu.logger = new ConsoleLogger(LogLevel.Error);
+
+const imageName = 'micropython.uf2';
+console.log(`Loading uf2 image ${imageName}`);
+loadUF2(imageName, mcu);
+
+const littlefs = 'littlefs-spi.img';
+
+if (fs.existsSync(littlefs)) {
+  console.log(`Loading littlefs image ${littlefs}`);
+  loadMicropythonFlashImage(littlefs, mcu);
+}
+
+let spiBuf = '';
+mcu.gpio[5].addListener((state: GPIOPinState, oldState: GPIOPinState) => {
+  if (!spiBuf) {
+    return;
+  }
+
+  if (state === GPIOPinState.High && oldState === GPIOPinState.Low) {
+    if (spiBuf !== args._?.shift()) {
+      console.log('SPI TEST FAILED.');
+      process.exit(1);
+    } else {
+      console.log('SPI MESSAGE RECEIVED.');
+      spiBuf = '';
+    }
+
+    if (args._.length === 0) {
+      console.log('SPI TEST PASSED.');
+      process.exit(0);
+    }
+  }
+});
+
+mcu.spi[0].onTransmit = (char) => {
+  spiBuf += String.fromCharCode(char);
+  mcu.spi[0].completeTransmit(0);
+};
+
+mcu.core.PC = 0x10000000;
+mcu.execute();

test/micropython/main-spi.py

@@ -0,0 +1,18 @@
+from machine import Pin, SPI
+
+spi = SPI(0)
+cs = Pin(5, Pin.OUT)
+cs(1)
+
+spi.init(baudrate=10 * 1024 * 1024, polarity=0, phase=0)
+cs(0)
+spi.write(b'hello world')
+cs(1)
+
+cs(0)
+spi.write(b'h')
+cs(1)
+
+cs(0)
+spi.write(b'0123456789abcdef0123456789abcdef0123456789abcdef')
+cs(1)

test/mklittlefs.py

@@ -1,16 +1,19 @@
 # Simple script to create a littlefs image for running the MicroPython test
 
 from littlefs import LittleFS
-from os.path import join
+from os.path import basename
+from sys import argv
 
-files = ['main.py']
-source_dir = 'test/micropython'
-output_image = 'littlefs.img'
+files = argv[2:]
+# files = ['test/micropython/main.py']
+output_image = argv[1]
 
 lfs = LittleFS(block_size=4096, block_count=352, prog_size=256)
+main = True
 for filename in files:
-    with open(join(source_dir, filename), 'r') as src_file, lfs.open(filename, 'w') as lfs_file:
+    with open(filename, 'r') as src_file, lfs.open("main.py" if main else basename(filename), 'w') as lfs_file:
         lfs_file.write(src_file.read())
+    main = False
 with open(output_image, 'wb') as fh:
     fh.write(lfs.context.buffer)