F1: SPI: remove compiler warnings + fix SdFat compatibility

Author: stevstrong

STM32F1/libraries/SPI/src/SPI.cpp

@@ -61,6 +61,8 @@ static void configure_gpios(spi_dev *dev, bool as_master);
 
 static spi_baud_rate determine_baud_rate(spi_dev *dev, uint32_t freq);
 
+static uint16_t ff = 0XFFFF;
+
 #if (BOARD_NR_SPI >= 3) && !defined(STM32_HIGH_DENSITY)
 #error "The SPI library is misconfigured: 3 SPI ports only available on high density STM32 devices"
 #endif
@@ -270,6 +272,7 @@ If someone finds this is not the case or sees a logic error with this let me kno
 
 void SPIClass::beginTransaction(uint8_t pin, SPISettings settings)
 {
+	(void)pin; // unused
     setBitOrder(settings.bitOrder);
     setDataMode(settings.dataMode);
     setDataSize(settings.dataSize);
@@ -412,13 +415,13 @@ void SPIClass::dmaTransferSet(const void *transmitBuf, void *receiveBuf) {
     dma_setup_transfer(_currentSetting->spiDmaDev, _currentSetting->spiRxDmaChannel, &_currentSetting->spi_d->regs->DR, dma_bit_size,
                      receiveBuf, dma_bit_size, (DMA_MINC_MODE | DMA_TRNS_CMPLT ));// receive buffer DMA
     if (!transmitBuf) {
-    transmitBuf = &ff;
-    dma_setup_transfer(_currentSetting->spiDmaDev, _currentSetting->spiTxDmaChannel, &_currentSetting->spi_d->regs->DR, dma_bit_size,
-                       (volatile void*)transmitBuf, dma_bit_size, (DMA_FROM_MEM));// Transmit FF repeatedly
+        transmitBuf = &ff;
+        dma_setup_transfer(_currentSetting->spiDmaDev, _currentSetting->spiTxDmaChannel, &_currentSetting->spi_d->regs->DR, dma_bit_size,
+                           (volatile void*)transmitBuf, dma_bit_size, (DMA_FROM_MEM));// Transmit FF repeatedly
     }
     else {
-    dma_setup_transfer(_currentSetting->spiDmaDev, _currentSetting->spiTxDmaChannel, &_currentSetting->spi_d->regs->DR, dma_bit_size,
-                       (volatile void*)transmitBuf, dma_bit_size, (DMA_MINC_MODE |  DMA_FROM_MEM ));// Transmit buffer DMA
+        dma_setup_transfer(_currentSetting->spiDmaDev, _currentSetting->spiTxDmaChannel, &_currentSetting->spi_d->regs->DR, dma_bit_size,
+                           (volatile void*)transmitBuf, dma_bit_size, (DMA_MINC_MODE |  DMA_FROM_MEM ));// Transmit buffer DMA
     }
     dma_set_priority(_currentSetting->spiDmaDev, _currentSetting->spiTxDmaChannel, DMA_PRIORITY_LOW);
     dma_set_priority(_currentSetting->spiDmaDev, _currentSetting->spiRxDmaChannel, DMA_PRIORITY_VERY_HIGH);
@@ -468,6 +471,12 @@ uint8 SPIClass::dmaTransfer(const void *transmitBuf, void *receiveBuf, uint16 le
     return dmaTransferRepeat(length);
 }
 
+uint8 SPIClass::dmaTransfer(const uint16 value, void *receiveBuf, uint16 length) {
+    ff = value;
+    dmaTransferSet(NULL, receiveBuf);
+    return dmaTransferRepeat(length);
+}
+
 /*  Roger Clark and Victor Perez, 2015
 *	Performs a DMA SPI send using a TX buffer.
 *	On exit TX buffer is not modified.
@@ -782,11 +791,11 @@ static const spi_baud_rate baud_rates[8] __FLASH__ = {
 * (CYCLES_PER_MICROSECOND == 72, APB2 at 72MHz, APB1 at 36MHz).
 */
 static spi_baud_rate determine_baud_rate(spi_dev *dev, uint32_t freq) {
-    uint32_t clock;
+    uint32_t clock = 0;
     switch (rcc_dev_clk(dev->clk_id)) {
     case RCC_APB2: clock = STM32_PCLK2; break; // 72 Mhz
     case RCC_APB1: clock = STM32_PCLK1; break; // 36 Mhz
-    case RCC_AHB:  clock = 0; break;    //There is no SPI on this bus, but it removes warning 
+    case RCC_AHB:  break;    //There is no SPI on this bus, but it removes warning 
     }
     clock /= 2;
     uint32_t i = 0;

STM32F1/libraries/SPI/src/SPI.h

@@ -160,7 +160,6 @@ class SPISettings {
 /*
  * Kept for compat.
  */
-static const uint8_t ff = 0XFF;
 
 /**
  * @brief Wirish SPI interface.
@@ -297,6 +296,7 @@ class SPIClass {
      * @param length Number of bytes in buffer to transmit.
 	 */
     uint8 dmaTransfer(const void * transmitBuf, void * receiveBuf, uint16 length);
+    uint8 dmaTransfer(const uint16 value, void * receiveBuf, uint16 length);
     void dmaTransferSet(const void *transmitBuf, void *receiveBuf);
     uint8 dmaTransferRepeat(uint16 length);