spi: stm32: Enable sending 16bits at a time in 8bit mode if possible
If possible, allow sending 16bits at once instead of 8bits. I found
large delays (up to 3us) between sending bytes due to Zephyr SPI
overhead, so allowing 16bits at a time if possible helps save that
time.
Signed-off-by: Pushpal Sidhu <psidhu.devel@gmail.com>
diff --git a/drivers/spi/spi_ll_stm32.c b/drivers/spi/spi_ll_stm32.c
index 7df2ea9..579f824 100644
--- a/drivers/spi/spi_ll_stm32.c
+++ b/drivers/spi/spi_ll_stm32.c
@@ -73,11 +73,40 @@
return 0;
}
-/* Shift a SPI frame as master. */
-static void spi_stm32_shift_m(SPI_TypeDef *spi, struct spi_stm32_data *data)
+static inline void spi_stm32_shift_m8(SPI_TypeDef *spi,
+ struct spi_stm32_data *data)
{
+ struct spi_context *ctx = &(data->ctx);
u16_t tx_frame = SPI_STM32_TX_NOP;
u16_t rx_frame;
+ bool xfer_16;
+
+ if (spi_context_tx_buf_on(ctx) && spi_context_rx_buf_on(ctx)) {
+ xfer_16 = (MIN(ctx->tx_len, ctx->rx_len) > 1) ? true : false;
+ } else if (spi_context_tx_buf_on(ctx)) {
+ xfer_16 = (ctx->tx_len > 1) ? true : false;
+ } else if (spi_context_rx_buf_on(ctx)) {
+ xfer_16 = (ctx->rx_len > 1) ? true : false;
+ } else {
+ /* Should never get here, but place case for it anyways */
+ return;
+ }
+
+#if defined(CONFIG_SPI_STM32_HAS_FIFO)
+ if (xfer_16) {
+ ll_func_set_fifo_threshold_16bit(spi);
+ } else {
+ ll_func_set_fifo_threshold_8bit(spi);
+ }
+#endif
+
+ if (xfer_16 && spi_context_tx_buf_on(ctx)) {
+ tx_frame = UNALIGNED_GET((u16_t *)(ctx->tx_buf));
+ spi_context_update_tx(ctx, 1, 2);
+ } else if (spi_context_tx_buf_on(ctx)) {
+ tx_frame = UNALIGNED_GET((u8_t *)(ctx->tx_buf));
+ spi_context_update_tx(ctx, 1, 1);
+ }
while (!ll_func_tx_is_empty(spi)) {
/* NOP */
@@ -95,37 +124,68 @@
}
#endif
- if (SPI_WORD_SIZE_GET(data->ctx.config->operation) == 8) {
- if (spi_context_tx_on(&data->ctx)) {
- tx_frame = UNALIGNED_GET((u8_t *)(data->ctx.tx_buf));
- }
- LL_SPI_TransmitData8(spi, tx_frame);
- /* The update is ignored if TX is off. */
- spi_context_update_tx(&data->ctx, 1, 1);
- } else {
- if (spi_context_tx_on(&data->ctx)) {
- tx_frame = UNALIGNED_GET((u16_t *)(data->ctx.tx_buf));
- }
+ if (xfer_16) {
LL_SPI_TransmitData16(spi, tx_frame);
- /* The update is ignored if TX is off. */
- spi_context_update_tx(&data->ctx, 2, 1);
+ } else {
+ LL_SPI_TransmitData8(spi, tx_frame);
}
while (!ll_func_rx_is_not_empty(spi)) {
/* NOP */
}
- if (SPI_WORD_SIZE_GET(data->ctx.config->operation) == 8) {
- rx_frame = LL_SPI_ReceiveData8(spi);
- if (spi_context_rx_buf_on(&data->ctx)) {
- UNALIGNED_PUT(rx_frame, (u8_t *)data->ctx.rx_buf);
- }
- spi_context_update_rx(&data->ctx, 1, 1);
- } else {
+ if (xfer_16) {
rx_frame = LL_SPI_ReceiveData16(spi);
- if (spi_context_rx_buf_on(&data->ctx)) {
- UNALIGNED_PUT(rx_frame, (u16_t *)data->ctx.rx_buf);
+ if (spi_context_rx_buf_on(ctx)) {
+ UNALIGNED_PUT(rx_frame, (u16_t *)ctx->rx_buf);
+ spi_context_update_rx(ctx, 1, 2);
}
+ } else {
+ rx_frame = LL_SPI_ReceiveData8(spi);
+ if (spi_context_rx_buf_on(ctx)) {
+ UNALIGNED_PUT(rx_frame, (u8_t *)ctx->rx_buf);
+ spi_context_update_rx(ctx, 1, 1);
+ }
+ }
+}
+
+static inline void spi_stm32_shift_m16(SPI_TypeDef *spi,
+ struct spi_stm32_data *data)
+{
+ u16_t tx_frame = SPI_STM32_TX_NOP;
+ u16_t rx_frame;
+
+ if (spi_context_tx_buf_on(&data->ctx)) {
+ tx_frame = UNALIGNED_GET((u16_t *)(data->ctx.tx_buf));
+ spi_context_update_tx(&data->ctx, 2, 1);
+ }
+
+ while (!ll_func_tx_is_empty(spi)) {
+ /* NOP */
+ }
+
+#ifdef CONFIG_SOC_SERIES_STM32MP1X
+ /* With the STM32MP1, if the device is the SPI master, we need to enable
+ * the start of the transfer with LL_SPI_StartMasterTransfer(spi)
+ */
+ if (LL_SPI_GetMode(spi) == LL_SPI_MODE_MASTER) {
+ LL_SPI_StartMasterTransfer(spi);
+ while (!LL_SPI_IsActiveMasterTransfer(spi)) {
+ /* NOP */
+ }
+ }
+#endif
+
+ LL_SPI_TransmitData16(spi, tx_frame);
+
+ while (!ll_func_rx_is_not_empty(spi)) {
+ /* NOP */
+ }
+
+ rx_frame = LL_SPI_ReceiveData16(spi);
+
+ if (spi_context_rx_buf_on(&data->ctx)) {
+ UNALIGNED_PUT(rx_frame, (u16_t *)data->ctx.rx_buf);
spi_context_update_rx(&data->ctx, 2, 1);
}
}
@@ -176,7 +236,11 @@
u16_t operation = data->ctx.config->operation;
if (SPI_OP_MODE_GET(operation) == SPI_OP_MODE_MASTER) {
- spi_stm32_shift_m(spi, data);
+ if (SPI_WORD_SIZE_GET(data->ctx.config->operation) == 8) {
+ spi_stm32_shift_m8(spi, data);
+ } else {
+ spi_stm32_shift_m16(spi, data);
+ }
} else {
spi_stm32_shift_s(spi, data);
}
