[PATCH 4/4] add SPI_SIMPLEX_RX/SPI_3WIRE_RX support for spi-stm32f4

[dillon . minfei]

From: dillon min <dillon.minfei@xxxxxxxxx>

add SPI_SIMPLEX_RX/SPI_3WIRE_RX in spi-stm32f4.c
for SPI_SIMPLEX_RX , as we running kernel in sdram, so
that the performance is not as good as internal flash,
need add send dummy data out while in rx,
otherwise will get many overrun errors.

Signed-off-by: dillon min <dillon.minfei@xxxxxxxxx>
---
 drivers/spi/spi-stm32.c | 26 ++++++++++++++++++++++----
 1 file changed, 22 insertions(+), 4 deletions(-)

diff --git a/drivers/spi/spi-stm32.c b/drivers/spi/spi-stm32.c
index 44ac6eb3..680cede 100644
--- a/drivers/spi/spi-stm32.c
+++ b/drivers/spi/spi-stm32.c
@@ -388,6 +388,10 @@ static int stm32h7_spi_get_fifo_size(struct stm32_spi *spi)
 	return count;
 }
 
+static void stm32f4_spi_tx_dummy(struct stm32_spi *spi)
+{
+	writeb_relaxed(0x55, spi->base + STM32F4_SPI_DR);
+}
 /**
  * stm32f4_spi_get_bpw_mask - Return bits per word mask
  * @spi: pointer to the spi controller data structure
@@ -811,7 +815,9 @@ static irqreturn_t stm32f4_spi_irq_event(int irq, void *dev_id)
 		mask |= STM32F4_SPI_SR_TXE;
 	}
 
-	if (!spi->cur_usedma && spi->cur_comm == SPI_FULL_DUPLEX) {
+	if (!spi->cur_usedma && (spi->cur_comm == SPI_FULL_DUPLEX ||
+				 spi->cur_comm == SPI_SIMPLEX_RX ||
+				 spi->cur_comm == SPI_3WIRE_RX)) {
 		/* TXE flag is set and is handled when RXNE flag occurs */
 		sr &= ~STM32F4_SPI_SR_TXE;
 		mask |= STM32F4_SPI_SR_RXNE | STM32F4_SPI_SR_OVR;
@@ -850,8 +856,10 @@ static irqreturn_t stm32f4_spi_irq_event(int irq, void *dev_id)
 		stm32f4_spi_read_rx(spi);
 		if (spi->rx_len == 0)
 			end = true;
-		else /* Load data for discontinuous mode */
+		else if (spi->tx_buf)/* Load data for discontinuous mode */
 			stm32f4_spi_write_tx(spi);
+		else if (spi->cur_comm == SPI_SIMPLEX_RX)
+			stm32f4_spi_tx_dummy(spi);
 	}
 
 end_irq:
@@ -1151,7 +1159,9 @@ static int stm32f4_spi_transfer_one_irq(struct stm32_spi *spi)
 	/* Enable the interrupts relative to the current communication mode */
 	if (spi->cur_comm == SPI_SIMPLEX_TX || spi->cur_comm == SPI_3WIRE_TX) {
 		cr2 |= STM32F4_SPI_CR2_TXEIE;
-	} else if (spi->cur_comm == SPI_FULL_DUPLEX) {
+	} else if (spi->cur_comm == SPI_FULL_DUPLEX ||
+				spi->cur_comm == SPI_SIMPLEX_RX ||
+				spi->cur_comm == SPI_3WIRE_RX) {
 		/* In transmit-only mode, the OVR flag is set in the SR register
 		 * since the received data are never read. Therefore set OVR
 		 * interrupt only when rx buffer is available.
@@ -1170,6 +1180,8 @@ static int stm32f4_spi_transfer_one_irq(struct stm32_spi *spi)
 	/* starting data transfer when buffer is loaded */
 	if (spi->tx_buf)
 		stm32f4_spi_write_tx(spi);
+	else if (spi->cur_comm == SPI_SIMPLEX_RX)
+		stm32f4_spi_tx_dummy(spi);
 
 	spin_unlock_irqrestore(&spi->lock, flags);
 
@@ -1462,9 +1474,15 @@ static int stm32f4_spi_set_mode(struct stm32_spi *spi, unsigned int comm_type)
 		stm32_spi_set_bits(spi, STM32F4_SPI_CR1,
 					STM32F4_SPI_CR1_BIDIMODE |
 					STM32F4_SPI_CR1_BIDIOE);
-	} else if (comm_type == SPI_FULL_DUPLEX) {
+	} else if (comm_type == SPI_FULL_DUPLEX ||
+				comm_type == SPI_SIMPLEX_RX) {
 		stm32_spi_clr_bits(spi, STM32F4_SPI_CR1,
 					STM32F4_SPI_CR1_BIDIMODE |
+					STM32F4_SPI_CR1_RXONLY);
+	} else if (comm_type == SPI_3WIRE_RX) {
+		stm32_spi_set_bits(spi, STM32F4_SPI_CR1,
+					STM32F4_SPI_CR1_BIDIMODE);
+		stm32_spi_clr_bits(spi, STM32F4_SPI_CR1,
 					STM32F4_SPI_CR1_BIDIOE);
 	} else {
 		return -EINVAL;
-- 
2.7.4