initial SPI DMA support

wokwi · Sep 2, 2023 · 7fdf050 · 7fdf050
1 parent 31f505f
commit 7fdf050
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Showing 2 changed files with 38 additions and 3 deletions.
diff --git a/src/peripherals/spi.ts b/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() {
@@ -159,6 +183,7 @@ export class RPSPI extends BasePeripheral implements Peripheral {
       case SSPDR:
         if (!this.rxFIFO.empty) {
           const value = this.rxFIFO.pull();
+          this.updateDMARx();
           this.fifosUpdated();
           return value;
         }
@@ -211,8 +236,10 @@ 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.updateDMATx();
           this.fifosUpdated();
         }
         return;

diff --git a/src/rp2040.ts b/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 +120,15 @@ 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_RX,
+    })];
 
   private stopped = true;