ESP32 Family: Add multiple transctions to SPI for improved efficency

ports/espressif/common-hal/busio/SPI.c

@@ -33,6 +33,7 @@
 #include "driver/spi_common_internal.h"
 
 #define SPI_MAX_DMA_BITS (SPI_MAX_DMA_LEN * 8)
+#define MAX_SPI_TRANSACTIONS 10
 
 static bool spi_never_reset[SOC_SPI_PERIPH_NUM];
 static spi_device_handle_t spi_handle[SOC_SPI_PERIPH_NUM];
@@ -59,7 +60,7 @@ static void set_spi_config(busio_spi_obj_t *self,
         .clock_speed_hz = baudrate,
         .mode = phase | (polarity << 1),
         .spics_io_num = -1, // No CS pin
-        .queue_size = 1,
+        .queue_size = MAX_SPI_TRANSACTIONS,
         .pre_cb = NULL
     };
     esp_err_t result = spi_bus_add_device(self->host_id, &device_config, &spi_handle[self->host_id]);
@@ -213,47 +214,61 @@ bool common_hal_busio_spi_transfer(busio_spi_obj_t *self,
         mp_raise_ValueError(translate("No MISO Pin"));
     }
 
-    spi_transaction_t transaction = { 0 };
+    spi_transaction_t transactions[MAX_SPI_TRANSACTIONS];
 
     // Round to nearest whole set of bits
     int bits_to_send = len * 8 / self->bits * self->bits;
 
     if (len <= 4) {
+        memset(&transactions[0], 0, sizeof(spi_transaction_t));
         if (data_out != NULL) {
-            memcpy(&transaction.tx_data, data_out, len);
+            memcpy(&transactions[0].tx_data, data_out, len);
         }
 
-        transaction.flags = SPI_TRANS_USE_TXDATA | SPI_TRANS_USE_RXDATA;
-        transaction.length = bits_to_send;
-        spi_device_transmit(spi_handle[self->host_id], &transaction);
+        transactions[0].flags = SPI_TRANS_USE_TXDATA | SPI_TRANS_USE_RXDATA;
+        transactions[0].length = bits_to_send;
+        spi_device_transmit(spi_handle[self->host_id], &transactions[0]);
 
         if (data_in != NULL) {
-            memcpy(data_in, &transaction.rx_data, len);
+            memcpy(data_in, &transactions[0].rx_data, len);
         }
     } else {
         int offset = 0;
         int bits_remaining = bits_to_send;
+        int cur_trans = 0;
 
         while (bits_remaining && !mp_hal_is_interrupted()) {
-            memset(&transaction, 0, sizeof(transaction));
 
-            transaction.length =
-                bits_remaining > SPI_MAX_DMA_BITS ? SPI_MAX_DMA_BITS : bits_remaining;
+            cur_trans = 0;
+            while (bits_remaining && (cur_trans != MAX_SPI_TRANSACTIONS)) {
+                memset(&transactions[cur_trans], 0, sizeof(spi_transaction_t));
 
-            if (data_out != NULL) {
-                transaction.tx_buffer = data_out + offset;
-            }
-            if (data_in != NULL) {
-                transaction.rx_buffer = data_in + offset;
-            }
+                transactions[cur_trans].length =
+                    bits_remaining > SPI_MAX_DMA_BITS ? SPI_MAX_DMA_BITS : bits_remaining;
 
-            spi_device_transmit(spi_handle[self->host_id], &transaction);
-            bits_remaining -= transaction.length;
+                if (data_out != NULL) {
+                    transactions[cur_trans].tx_buffer = data_out + offset;
+                }
+                if (data_in != NULL) {
+                    transactions[cur_trans].rx_buffer = data_in + offset;
+                }
 
-            // doesn't need ceil(); loop ends when bits_remaining is 0
-            offset += transaction.length / 8;
+                bits_remaining -= transactions[cur_trans].length;
+
+                // doesn't need ceil(); loop ends when bits_remaining is 0
+                offset += transactions[cur_trans].length / 8;
+                cur_trans++;
+            }
 
-            RUN_BACKGROUND_TASKS;
+            for (int i = 0; i < cur_trans; i++) {
+                spi_device_queue_trans(spi_handle[self->host_id], &transactions[i], portMAX_DELAY);
+            }
+
+            spi_transaction_t *rtrans;
+            for (int x = 0; x < cur_trans; x++) {
+                RUN_BACKGROUND_TASKS;
+                spi_device_get_trans_result(spi_handle[self->host_id], &rtrans, portMAX_DELAY);
+            }
         }
     }
     return true;