linux-kernel - [PATCH v2 16/28] spi: s3c64xx: simplify s3c64xx_wait_for

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Message-ID: <20240125145007.748295-17-tudor.ambarus@linaro.org>
Date: Thu, 25 Jan 2024 14:49:54 +0000
From: Tudor Ambarus <tudor.ambarus@...aro.org>
To: broonie@...nel.org,
	andi.shyti@...nel.org,
	arnd@...db.de
Cc: robh+dt@...nel.org,
	krzysztof.kozlowski+dt@...aro.org,
	conor+dt@...nel.org,
	alim.akhtar@...sung.com,
	linux-spi@...r.kernel.org,
	linux-samsung-soc@...r.kernel.org,
	devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-arch@...r.kernel.org,
	andre.draszik@...aro.org,
	peter.griffin@...aro.org,
	semen.protsenko@...aro.org,
	kernel-team@...roid.com,
	willmcvicker@...gle.com,
	Tudor Ambarus <tudor.ambarus@...aro.org>
Subject: [PATCH v2 16/28] spi: s3c64xx: simplify s3c64xx_wait_for_pio()

s3c64xx_spi_transfer_one() makes sure that for PIO the xfer->len is
always smaller than the fifo size. Since we can't receive more that the
FIFO size, droop the loop handling, the code becomes less misleading.

Signed-off-by: Tudor Ambarus <tudor.ambarus@...aro.org>
---
 drivers/spi/spi-s3c64xx.c | 75 +++++++++------------------------------
 1 file changed, 17 insertions(+), 58 deletions(-)

diff --git a/drivers/spi/spi-s3c64xx.c b/drivers/spi/spi-s3c64xx.c
index d2dd28ff00c6..00a0878aeb80 100644
--- a/drivers/spi/spi-s3c64xx.c
+++ b/drivers/spi/spi-s3c64xx.c
@@ -485,26 +485,6 @@ static int s3c64xx_enable_datapath(struct s3c64xx_spi_driver_data *sdd,
 	return 0;
 }
 
-static u32 s3c64xx_spi_wait_for_timeout(struct s3c64xx_spi_driver_data *sdd,
-					int timeout_ms)
-{
-	void __iomem *regs = sdd->regs;
-	unsigned long val = 1;
-	u32 status;
-	u32 max_fifo = FIFO_DEPTH(sdd);
-
-	if (timeout_ms)
-		val = msecs_to_loops(timeout_ms);
-
-	do {
-		status = readl(regs + S3C64XX_SPI_STATUS);
-	} while (FIELD_GET(S3C64XX_SPI_ST_RX_FIFO_LVL, status) < max_fifo &&
-		 --val);
-
-	/* return the actual received data length */
-	return FIELD_GET(S3C64XX_SPI_ST_RX_FIFO_LVL, status);
-}
-
 static int s3c64xx_wait_for_dma(struct s3c64xx_spi_driver_data *sdd,
 				struct spi_transfer *xfer)
 {
@@ -553,13 +533,11 @@ static int s3c64xx_wait_for_pio(struct s3c64xx_spi_driver_data *sdd,
 				struct spi_transfer *xfer, bool use_irq)
 {
 	void __iomem *regs = sdd->regs;
+	u8 *buf = xfer->rx_buf;
+	unsigned long time_us;
 	unsigned long val;
-	u32 status;
-	int loops;
-	u32 cpy_len;
-	u8 *buf;
+	u32 status, len;
 	int ms;
-	unsigned long time_us;
 
 	/* microsecs to xfer 'len' bytes @ 'cur_speed' */
 	time_us = (xfer->len * 8 * 1000 * 1000) / sdd->cur_speed;
@@ -582,48 +560,29 @@ static int s3c64xx_wait_for_pio(struct s3c64xx_spi_driver_data *sdd,
 		status = readl(regs + S3C64XX_SPI_STATUS);
 	} while (FIELD_GET(S3C64XX_SPI_ST_RX_FIFO_LVL, status) < xfer->len &&
 		 --val);
-
 	if (!val)
 		return -EIO;
 
 	/* If it was only Tx */
-	if (!xfer->rx_buf) {
+	if (!buf) {
 		sdd->state &= ~TXBUSY;
 		return 0;
 	}
 
-	/*
-	 * If the receive length is bigger than the controller fifo
-	 * size, calculate the loops and read the fifo as many times.
-	 * loops = length / max fifo size (calculated by using the
-	 * fifo mask).
-	 * For any size less than the fifo size the below code is
-	 * executed atleast once.
-	 */
-	loops = xfer->len / FIFO_DEPTH(sdd);
-	buf = xfer->rx_buf;
-	do {
-		/* wait for data to be received in the fifo */
-		cpy_len = s3c64xx_spi_wait_for_timeout(sdd,
-						       (loops ? ms : 0));
-
-		switch (sdd->cur_bpw) {
-		case 32:
-			ioread32_rep(regs + S3C64XX_SPI_RX_DATA,
-				     buf, cpy_len / 4);
-			break;
-		case 16:
-			ioread16_rep(regs + S3C64XX_SPI_RX_DATA,
-				     buf, cpy_len / 2);
-			break;
-		default:
-			ioread8_rep(regs + S3C64XX_SPI_RX_DATA,
-				    buf, cpy_len);
-			break;
-		}
+	len = FIELD_GET(S3C64XX_SPI_ST_RX_FIFO_LVL, status);
+
+	switch (sdd->cur_bpw) {
+	case 32:
+		ioread32_rep(regs + S3C64XX_SPI_RX_DATA, buf, len / 4);
+		break;
+	case 16:
+		ioread16_rep(regs + S3C64XX_SPI_RX_DATA, buf, len / 2);
+		break;
+	default:
+		ioread8_rep(regs + S3C64XX_SPI_RX_DATA, buf, len);
+		break;
+	}
 
-		buf = buf + cpy_len;
-	} while (loops--);
 	sdd->state &= ~RXBUSY;
 
 	return 0;
-- 
2.43.0.429.g432eaa2c6b-goog