Input: ad714x - use DMA-safe buffers for spi_write()

spi_write() requires use of DMA-safe (cacheline aligned) buffers.
Also use the same buffers when reading data since to avoid extra
locking and potential memory allocation in spi_write_then_read().

Acked-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

1 files changed, 37 insertions, 14 deletions

diff --git a/drivers/input/misc/ad714x-spi.c b/drivers/input/misc/ad714x-spi.c
index 0c7f948..306577d 100644
--- a/drivers/input/misc/ad714x-spi.c
+++ b/drivers/input/misc/ad714x-spi.c
@@ -30,31 +30,54 @@ static int ad714x_spi_resume(struct device *dev)
 
 static SIMPLE_DEV_PM_OPS(ad714x_spi_pm, ad714x_spi_suspend, ad714x_spi_resume);
 
-static int ad714x_spi_read(struct device *dev,
+static int ad714x_spi_read(struct ad714x_chip *chip,
 			   unsigned short reg, unsigned short *data)
 {
-	struct spi_device *spi = to_spi_device(dev);
-	unsigned short tx = cpu_to_be16(AD714x_SPI_CMD_PREFIX |
+	struct spi_device *spi = to_spi_device(chip->dev);
+	struct spi_message message;
+	struct spi_transfer xfer[2];
+	int error;
+
+	spi_message_init(&message);
+	memset(xfer, 0, sizeof(xfer));
+
+	chip->xfer_buf[0] = cpu_to_be16(AD714x_SPI_CMD_PREFIX |
 					AD714x_SPI_READ | reg);
-	int ret;
+	xfer[0].tx_buf = &chip->xfer_buf[0];
+	xfer[0].len = sizeof(chip->xfer_buf[0]);
+	spi_message_add_tail(&xfer[0], &message);
 
-	ret = spi_write_then_read(spi, &tx, 2, data, 2);
+	xfer[1].rx_buf = &chip->xfer_buf[1];
+	xfer[1].len = sizeof(chip->xfer_buf[1]);
+	spi_message_add_tail(&xfer[1], &message);
 
-	*data = be16_to_cpup(data);
+	error = spi_sync(spi, &message);
+	if (unlikely(error)) {
+		dev_err(chip->dev, "SPI read error: %d\n", error);
+		return error;
+	}
 
-	return ret;
+	*data = be16_to_cpu(chip->xfer_buf[1]);
+	return 0;
 }
 
-static int ad714x_spi_write(struct device *dev,
+static int ad714x_spi_write(struct ad714x_chip *chip,
 			    unsigned short reg, unsigned short data)
 {
-	struct spi_device *spi = to_spi_device(dev);
-	unsigned short tx[2] = {
-		cpu_to_be16(AD714x_SPI_CMD_PREFIX | reg),
-		cpu_to_be16(data)
-	};
+	struct spi_device *spi = to_spi_device(chip->dev);
+	int error;
 
-	return spi_write(spi, (u8 *)tx, 4);
+	chip->xfer_buf[0] = cpu_to_be16(AD714x_SPI_CMD_PREFIX | reg);
+	chip->xfer_buf[1] = cpu_to_be16(data);
+
+	error = spi_write(spi, (u8 *)chip->xfer_buf,
+			  2 * sizeof(*chip->xfer_buf));
+	if (unlikely(error)) {
+		dev_err(chip->dev, "SPI write error: %d\n", error);
+		return error;
+	}
+
+	return 0;
 }
 
 static int __devinit ad714x_spi_probe(struct spi_device *spi)