[PATCH 6/6] spi: imx: enable DMA mode for target operation

[Carlos Song <carlos.song@nxp.com>]

Enable DMA mode for SPI IMX in target mode.
Disable the word delay feature for target mode, because target mode should
always keep high performance to make sure it can follow the master. Target
mode continues to operate in dynamic burst mode.

Signed-off-by: Carlos Song <carlos.song@nxp.com>
---
 drivers/spi/spi-imx.c | 78 +++++++++++++++++++++++++++++++------------
 1 file changed, 56 insertions(+), 22 deletions(-)

diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c
index f02a47fbba8a..16b7d2f45012 100644
--- a/drivers/spi/spi-imx.c
+++ b/drivers/spi/spi-imx.c
@@ -264,9 +264,6 @@ static bool spi_imx_can_dma(struct spi_controller *controller, struct spi_device
 	if (!controller->dma_rx)
 		return false;
 
-	if (spi_imx->target_mode)
-		return false;
-
 	if (transfer->len < spi_imx->devtype_data->fifo_size)
 		return false;
 
@@ -1756,23 +1753,51 @@ static int spi_imx_dma_submit(struct spi_imx_data *spi_imx,
 
 	transfer_timeout = spi_imx_calculate_timeout(spi_imx, transfer->len);
 
-	/* Wait SDMA to finish the data transfer.*/
-	time_left = wait_for_completion_timeout(&spi_imx->dma_tx_completion,
-						transfer_timeout);
-	if (!time_left) {
-		dev_err(spi_imx->dev, "I/O Error in DMA TX\n");
-		dmaengine_terminate_all(controller->dma_tx);
-		dmaengine_terminate_all(controller->dma_rx);
-		return -ETIMEDOUT;
-	}
+	if (!spi_imx->target_mode) {
+		/* Wait SDMA to finish the data transfer.*/
+		time_left = wait_for_completion_timeout(&spi_imx->dma_tx_completion,
+							transfer_timeout);
+		if (!time_left) {
+			dev_err(spi_imx->dev, "I/O Error in DMA TX\n");
+			dmaengine_terminate_all(controller->dma_tx);
+			dmaengine_terminate_all(controller->dma_rx);
+			return -ETIMEDOUT;
+		}
 
-	time_left = wait_for_completion_timeout(&spi_imx->dma_rx_completion,
-						transfer_timeout);
-	if (!time_left) {
-		dev_err(&controller->dev, "I/O Error in DMA RX\n");
-		spi_imx->devtype_data->reset(spi_imx);
-		dmaengine_terminate_all(controller->dma_rx);
-		return -ETIMEDOUT;
+		time_left = wait_for_completion_timeout(&spi_imx->dma_rx_completion,
+							transfer_timeout);
+		if (!time_left) {
+			dev_err(&controller->dev, "I/O Error in DMA RX\n");
+			spi_imx->devtype_data->reset(spi_imx);
+			dmaengine_terminate_all(controller->dma_rx);
+			return -ETIMEDOUT;
+		}
+	} else {
+		spi_imx->target_aborted = false;
+
+		if (wait_for_completion_interruptible(&spi_imx->dma_tx_completion) ||
+		    spi_imx->target_aborted) {
+			dev_dbg(spi_imx->dev, "I/O Error in DMA TX interrupted\n");
+			dmaengine_terminate_all(controller->dma_tx);
+			dmaengine_terminate_all(controller->dma_rx);
+			return -EINTR;
+		}
+
+		if (wait_for_completion_interruptible(&spi_imx->dma_rx_completion) ||
+		    spi_imx->target_aborted) {
+			dev_dbg(spi_imx->dev, "I/O Error in DMA RX interrupted\n");
+			dmaengine_terminate_all(controller->dma_rx);
+			return -EINTR;
+		}
+
+		/*
+		 * ECSPI has a HW issue when works in Target mode, after 64 words
+		 * writtern to TXFIFO, even TXFIFO becomes empty, ECSPI_TXDATA keeps
+		 * shift out the last word data, so we have to disable ECSPI when in
+		 * target mode after the transfer completes.
+		 */
+		if (spi_imx->devtype_data->disable)
+			spi_imx->devtype_data->disable(spi_imx);
 	}
 
 	return 0;
@@ -1895,10 +1920,16 @@ static int spi_imx_dma_package_transfer(struct spi_imx_data *spi_imx,
 static int spi_imx_dma_transfer(struct spi_imx_data *spi_imx,
 				struct spi_transfer *transfer)
 {
-	bool word_delay = transfer->word_delay.value != 0;
+	bool word_delay = transfer->word_delay.value != 0 && !spi_imx->target_mode;
 	int ret;
 	int i;
 
+	if (transfer->len > MX53_MAX_TRANSFER_BYTES && spi_imx->target_mode) {
+		dev_err(spi_imx->dev, "Transaction too big, max size is %d bytes\n",
+			MX53_MAX_TRANSFER_BYTES);
+		return -EMSGSIZE;
+	}
+
 	ret = spi_imx_dma_data_prepare(spi_imx, transfer, word_delay);
 	if (ret < 0) {
 		transfer->error |= SPI_TRANS_FAIL_NO_START;
@@ -2104,7 +2135,7 @@ static int spi_imx_transfer_one(struct spi_controller *controller,
 	while (spi_imx->devtype_data->rx_available(spi_imx))
 		readl(spi_imx->base + MXC_CSPIRXDATA);
 
-	if (spi_imx->target_mode)
+	if (spi_imx->target_mode && !spi_imx->usedma)
 		return spi_imx_pio_transfer_target(spi, transfer);
 
 	/*
@@ -2116,7 +2147,10 @@ static int spi_imx_transfer_one(struct spi_controller *controller,
 		ret = spi_imx_dma_transfer(spi_imx, transfer);
 		if (transfer->error & SPI_TRANS_FAIL_NO_START) {
 			spi_imx->usedma = false;
-			return spi_imx_pio_transfer(spi, transfer);
+			if (spi_imx->target_mode)
+				return spi_imx_pio_transfer_target(spi, transfer);
+			else
+				return spi_imx_pio_transfer(spi, transfer);
 		}
 		return ret;
 	}
-- 
2.34.1