HT32: SPI: avoid write collisions when SPI FIFO is disabled

This fixes possible write collisions experienced when SPI FIFO is
disabled due to not checking whether the SPI shift register is empty
before writing. This is done by checking TXE flag instead of TXBE flag
when the FIFO is not used.

os/common/ext/CMSIS/HT32/HT32F165x/ht32f165x_reg.h

@@ -495,6 +495,7 @@ typedef struct {
 #define SPI_CR1_FORMAT_MODE2        (0x6U << 8)
 #define SPI_CR1_FORMAT_MODE3        (0x5U << 8)
 #define SPI_IER_RXBNEIEN            (1U << 2)
+#define SPI_IER_TXEIEN              (1U << 1)
 #define SPI_IER_TXBEIEN             (1U << 0)
 #define SPI_SR_RXBNE                (1U << 2)
 #define SPI_SR_TXE                  (1U << 1)

os/common/ext/CMSIS/HT32/HT32F523xx/ht32f523x2_reg.h

@@ -477,6 +477,7 @@ typedef struct {
 #define SPI_CR1_FORMAT_MODE2        (0x6U << 8)
 #define SPI_CR1_FORMAT_MODE3        (0x5U << 8)
 #define SPI_IER_RXBNEIEN            (1U << 2)
+#define SPI_IER_TXEIEN              (1U << 1)
 #define SPI_IER_TXBEIEN             (1U << 0)
 #define SPI_SR_RXBNE                (1U << 2)
 #define SPI_SR_TXE                  (1U << 1)

os/hal/ports/HT32/LLD/SPIv1/hal_spi_lld.c

@@ -76,8 +76,14 @@ static void spi_lld_tx(SPIDriver * const spip) {
 
     while (spip->txcnt) {
         sr = spip->SPI->SR;
-        if ((sr & SPI_SR_TXBE) == 0)
-            return;
+        // avoid write collision
+        if (spip->SPI->FCR & SPI_FCR_FIFOEN) {
+            if ((sr & SPI_SR_TXBE) == 0)
+                return;
+        } else {
+            if ((sr & SPI_SR_TXE) == 0)
+                return;
+        }
         if (spip->txptr) {
             fd = *spip->txptr++;
         } else {
@@ -260,7 +266,7 @@ void spi_lld_exchange(SPIDriver *spip, size_t n,
     spip->txptr = txbuf;
     spip->rxptr = rxbuf;
     spip->rxcnt = spip->txcnt = n;
-    spip->SPI->IER = SPI_IER_RXBNEIEN | SPI_IER_TXBEIEN;
+    spip->SPI->IER = SPI_IER_RXBNEIEN | SPI_IER_TXBEIEN | SPI_IER_TXEIEN;
 }
 
 /**