Implement busTransferMultiple abstraction layer

src/main/drivers/bus.c

@@ -206,25 +206,40 @@ void busDeviceWriteScratchpad(busDevice_t * dev, uint32_t value)
 
 bool busTransfer(const busDevice_t * dev, uint8_t * rxBuf, const uint8_t * txBuf, int length)
 {
+#ifdef USE_SPI
+    // busTransfer function is only supported on SPI bus
+    if (dev->busType == BUSTYPE_SPI) {
+        busTransferDescriptor_t dsc = {
+            .rxBuf = rxBuf,
+            .txBuf = txBuf,
+            .length = length
+        };
+
+        return spiBusTransferMultiple(dev, &dsc, 1);
+    }
+#else
     UNUSED(rxBuf);
     UNUSED(txBuf);
     UNUSED(length);
-
-    switch (dev->busType) {
-        case BUSTYPE_SPI:
-#ifdef USE_SPI
-            return spiBusTransfer(dev, rxBuf, txBuf, length);
-#else
-            return false;
 #endif
 
-        case BUSTYPE_I2C:
-            // Raw transfer operation is not supported on I2C
     return false;
+}
 
-        default:
+bool busTransferMultiple(const busDevice_t * dev, busTransferDescriptor_t * dsc, int count)
-            return false;
+{
+#ifdef USE_SPI
+    // busTransfer function is only supported on SPI bus
+    if (dev->busType == BUSTYPE_SPI) {
+        return spiBusTransferMultiple(dev, dsc, count);
     }
+#else
+    UNUSED(rxBuf);
+    UNUSED(txBuf);
+    UNUSED(length);
+#endif
+
+    return false;
 }
 
 bool busWriteBuf(const busDevice_t * dev, uint8_t reg, const uint8_t * data, uint8_t length)

src/main/drivers/bus.h

@@ -220,6 +220,13 @@ extern const busDeviceDescriptor_t __busdev_registry_end[];
     BUSDEV_REGISTER_I2C_F(_name, _devHw, _i2cBus, _devAddr, _irqPin, _tag, _flags)
 
 
+// busTransfer and busTransferMultiple are supported only on full-duplex SPI bus
+typedef struct busTransferDescriptor_s {
+    uint8_t *       rxBuf;
+    const uint8_t * txBuf;
+    uint32_t        length;
+} busTransferDescriptor_t;
+
 /* Internal abstraction function */
 bool i2cBusWriteBuffer(const busDevice_t * dev, uint8_t reg, const uint8_t * data, uint8_t length);
 bool i2cBusWriteRegister(const busDevice_t * dev, uint8_t reg, uint8_t data);
@@ -228,7 +235,7 @@ bool i2cBusReadRegister(const busDevice_t * dev, uint8_t reg, uint8_t * data);
 
 
 void spiBusSetSpeed(const busDevice_t * dev, busSpeed_e speed);
-bool spiBusTransfer(const busDevice_t * dev, uint8_t * rxBuf, const uint8_t * txBuf, int length);
+bool spiBusTransferMultiple(const busDevice_t * dev, busTransferDescriptor_t * dsc, int count);
 bool spiBusWriteBuffer(const busDevice_t * dev, uint8_t reg, const uint8_t * data, uint8_t length);
 bool spiBusWriteRegister(const busDevice_t * dev, uint8_t reg, uint8_t data);
 bool spiBusReadBuffer(const busDevice_t * dev, uint8_t reg, uint8_t * data, uint8_t length);
@@ -248,8 +255,10 @@ void busDeviceWriteScratchpad(busDevice_t * dev, uint32_t value);
 
 void busSetSpeed(const busDevice_t * dev, busSpeed_e speed);
 
-bool busTransfer(const busDevice_t * dev, uint8_t * rxBuf, const uint8_t * txBuf, int length);
 bool busWriteBuf(const busDevice_t * busdev, uint8_t reg, const uint8_t * data, uint8_t length);
 bool busReadBuf(const busDevice_t * busdev, uint8_t reg, uint8_t * data, uint8_t length);
 bool busRead(const busDevice_t * busdev, uint8_t reg, uint8_t * data);
 bool busWrite(const busDevice_t * busdev, uint8_t reg, uint8_t data);
+
+bool busTransfer(const busDevice_t * dev, uint8_t * rxBuf, const uint8_t * txBuf, int length);
+bool busTransferMultiple(const busDevice_t * dev, busTransferDescriptor_t * buffers, int count);

src/main/drivers/bus_busdev_spi.c

@@ -37,12 +37,16 @@ void spiBusSetSpeed(const busDevice_t * dev, busSpeed_e speed)
 }
 
 
-bool spiBusTransfer(const busDevice_t * dev, uint8_t * rxBuf, const uint8_t * txBuf, int length)
+bool spiBusTransferMultiple(const busDevice_t * dev, busTransferDescriptor_t * dsc, int count)
 {
     SPI_TypeDef * instance = spiInstanceByDevice(dev->busdev.spi.spiBus);
 
     IOLo(dev->busdev.spi.csnPin);
-    spiTransfer(instance, rxBuf, txBuf, length);
+
+    for (int n = 0; n < count; n++) {
+        spiTransfer(instance, dsc[n].rxBuf, dsc[n].txBuf, dsc[n].length);
+    }
+
     IOHi(dev->busdev.spi.csnPin);
 
     return true;