to_be_discussed: SPI: allow old school write() without beginTransmission()

Author: facchinm

Diff for: libraries/SPI/SPI.cpp

@@ -8,7 +8,9 @@
 #include "zephyrInternal.h"
 #include <zephyr/kernel.h>
 
-arduino::ZephyrSPI::ZephyrSPI(const struct device *spi) : spi_dev(spi) {}
+arduino::ZephyrSPI::ZephyrSPI(const struct device *spi) : spi_dev(spi) {
+  memset(&config, 0, sizeof(config));
+}
 
 uint8_t arduino::ZephyrSPI::transfer(uint8_t data) {
   int ret;
@@ -24,6 +26,10 @@ uint8_t arduino::ZephyrSPI::transfer(uint8_t data) {
       .count = 1,
   };
 
+  if (config.frequency == 0) {
+    beginTransaction(DEFAULT_SPI_SETTINGS);
+  }
+
   ret = spi_transceive(spi_dev, &config, &tx_buf_set, &rx_buf_set);
   if (ret < 0) {
     return 0;
@@ -46,6 +52,10 @@ uint16_t arduino::ZephyrSPI::transfer16(uint16_t data) {
       .count = 1,
   };
 
+  if (config.frequency == 0) {
+    beginTransaction(DEFAULT_SPI_SETTINGS);
+  }
+
   ret = spi_transceive(spi_dev, &config, &tx_buf_set, &rx_buf_set);
   if (ret < 0) {
     return 0;
@@ -55,7 +65,7 @@ uint16_t arduino::ZephyrSPI::transfer16(uint16_t data) {
 }
 
 void arduino::ZephyrSPI::transfer(void *buf, size_t count) {
-  int ret;
+
   const struct spi_buf tx_buf = {.buf = buf, .len = count};
   const struct spi_buf_set tx_buf_set = {
       .buffers = &tx_buf,
@@ -69,6 +79,10 @@ void arduino::ZephyrSPI::transfer(void *buf, size_t count) {
       .count = 1,
   };
 
+  if (config.frequency == 0) {
+    beginTransaction(DEFAULT_SPI_SETTINGS);
+  }
+
   spi_transceive(spi_dev, &config, &tx_buf_set, &rx_buf_set);
   memcpy(buf, rx, count);
 }