[PATCH v4 2/6] spi: spi-fsl-dspi: Store status directly in cur_msg->status

[James Clark <james.clark@linaro.org>]

This will allow us to return a status from the interrupt handler in a
later commit and avoids copying it at the end of
dspi_transfer_one_message(). For consistency make polling and DMA modes
use the same mechanism.

Refactor dspi_rxtx() and dspi_poll() to not return -EINPROGRESS because
this isn't actually a status that was ever returned to the core layer
but some internal state. Wherever that was used we can look at dspi->len
instead.

No functional changes intended.

Signed-off-by: James Clark <james.clark@linaro.org>
---
 drivers/spi/spi-fsl-dspi.c | 70 ++++++++++++++++++++++++----------------------
 1 file changed, 36 insertions(+), 34 deletions(-)

diff --git a/drivers/spi/spi-fsl-dspi.c b/drivers/spi/spi-fsl-dspi.c
index 4bd4377551b5..65567745fe9a 100644
--- a/drivers/spi/spi-fsl-dspi.c
+++ b/drivers/spi/spi-fsl-dspi.c
@@ -591,11 +591,10 @@ static int dspi_next_xfer_dma_submit(struct fsl_dspi *dspi)
 
 static void dspi_setup_accel(struct fsl_dspi *dspi);
 
-static int dspi_dma_xfer(struct fsl_dspi *dspi)
+static void dspi_dma_xfer(struct fsl_dspi *dspi)
 {
 	struct spi_message *message = dspi->cur_msg;
 	struct device *dev = &dspi->pdev->dev;
-	int ret = 0;
 
 	/*
 	 * dspi->len gets decremented by dspi_pop_tx_pushr in
@@ -612,14 +611,12 @@ static int dspi_dma_xfer(struct fsl_dspi *dspi)
 		message->actual_length += dspi->words_in_flight *
 					  dspi->oper_word_size;
 
-		ret = dspi_next_xfer_dma_submit(dspi);
-		if (ret) {
+		message->status = dspi_next_xfer_dma_submit(dspi);
+		if (message->status) {
 			dev_err(dev, "DMA transfer failed\n");
 			break;
 		}
 	}
-
-	return ret;
 }
 
 static int dspi_request_dma(struct fsl_dspi *dspi, phys_addr_t phy_addr)
@@ -986,36 +983,40 @@ static void dspi_fifo_write(struct fsl_dspi *dspi)
 				dspi->progress, !dspi->irq);
 }
 
-static int dspi_rxtx(struct fsl_dspi *dspi)
+static void dspi_rxtx(struct fsl_dspi *dspi)
 {
 	dspi_fifo_read(dspi);
 
 	if (!dspi->len)
 		/* Success! */
-		return 0;
+		return;
 
 	dspi_fifo_write(dspi);
-
-	return -EINPROGRESS;
 }
 
-static int dspi_poll(struct fsl_dspi *dspi)
+static void dspi_poll(struct fsl_dspi *dspi)
 {
-	int tries = 1000;
+	int tries;
 	u32 spi_sr;
 
-	do {
-		regmap_read(dspi->regmap, SPI_SR, &spi_sr);
-		regmap_write(dspi->regmap, SPI_SR, spi_sr);
+	while (dspi->len) {
+		for (tries = 1000; tries > 0; --tries) {
+			regmap_read(dspi->regmap, SPI_SR, &spi_sr);
+			regmap_write(dspi->regmap, SPI_SR, spi_sr);
 
-		if (spi_sr & SPI_SR_CMDTCF)
-			break;
-	} while (--tries);
+			if (spi_sr & SPI_SR_CMDTCF)
+				break;
+		}
 
-	if (!tries)
-		return -ETIMEDOUT;
+		if (!tries) {
+			dspi->cur_msg->status = -ETIMEDOUT;
+			return;
+		}
 
-	return dspi_rxtx(dspi);
+		dspi_rxtx(dspi);
+	}
+
+	dspi->cur_msg->status = 0;
 }
 
 static irqreturn_t dspi_interrupt(int irq, void *dev_id)
@@ -1029,8 +1030,13 @@ static irqreturn_t dspi_interrupt(int irq, void *dev_id)
 	if (!(spi_sr & SPI_SR_CMDTCF))
 		return IRQ_NONE;
 
-	if (dspi_rxtx(dspi) == 0)
+	dspi_rxtx(dspi);
+
+	if (!dspi->len) {
+		if (dspi->cur_msg)
+			WRITE_ONCE(dspi->cur_msg->status, 0);
 		complete(&dspi->xfer_done);
+	}
 
 	return IRQ_HANDLED;
 }
@@ -1060,7 +1066,6 @@ static int dspi_transfer_one_message(struct spi_controller *ctlr,
 	struct spi_device *spi = message->spi;
 	struct spi_transfer *transfer;
 	bool cs = false;
-	int status = 0;
 	u32 val = 0;
 	bool cs_change = false;
 
@@ -1120,7 +1125,7 @@ static int dspi_transfer_one_message(struct spi_controller *ctlr,
 				       dspi->progress, !dspi->irq);
 
 		if (dspi->devtype_data->trans_mode == DSPI_DMA_MODE) {
-			status = dspi_dma_xfer(dspi);
+			dspi_dma_xfer(dspi);
 		} else {
 			/*
 			 * Reinitialize the completion before transferring data
@@ -1134,15 +1139,12 @@ static int dspi_transfer_one_message(struct spi_controller *ctlr,
 
 			dspi_fifo_write(dspi);
 
-			if (dspi->irq) {
+			if (dspi->irq)
 				wait_for_completion(&dspi->xfer_done);
-			} else {
-				do {
-					status = dspi_poll(dspi);
-				} while (status == -EINPROGRESS);
-			}
+			else
+				dspi_poll(dspi);
 		}
-		if (status)
+		if (READ_ONCE(message->status))
 			break;
 
 		spi_transfer_delay_exec(transfer);
@@ -1151,7 +1153,8 @@ static int dspi_transfer_one_message(struct spi_controller *ctlr,
 			dspi_deassert_cs(spi, &cs);
 	}
 
-	if (status || !cs_change) {
+	dspi->cur_msg = NULL;
+	if (message->status || !cs_change) {
 		/* Put DSPI in stop mode */
 		regmap_update_bits(dspi->regmap, SPI_MCR,
 				   SPI_MCR_HALT, SPI_MCR_HALT);
@@ -1160,10 +1163,9 @@ static int dspi_transfer_one_message(struct spi_controller *ctlr,
 			;
 	}
 
-	message->status = status;
 	spi_finalize_current_message(ctlr);
 
-	return status;
+	return message->status;
 }
 
 static int dspi_set_mtf(struct fsl_dspi *dspi)

-- 
2.34.1