spi: bcm2835aux: fix CPOL/CPHA setting

The auxiliary spi supports only CPHA=0 modes as the first bit is
always output to the pin before the first clock cycle. In CPHA=1
modes the first clock edge outputs the second bit hence the slave
can never read the first bit.

Also the CPHA registers switch between clocking data in/out on
rising/falling edge hence depend on the CPOL setting.

Signed-off-by: Stephan Olbrich <stephanolbrich@gmx.de>
Reviewed-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/drivers/spi/spi-bcm2835aux.c b/drivers/spi/spi-bcm2835aux.c
index a6e25c6..496f9ad 100644 (file)
--- a/drivers/spi/spi-bcm2835aux.c
+++ b/drivers/spi/spi-bcm2835aux.c
@@ -64,9 +64,9 @@
 #define BCM2835_AUX_SPI_CNTL0_VAR_WIDTH        0x00004000
 #define BCM2835_AUX_SPI_CNTL0_DOUTHOLD 0x00003000
 #define BCM2835_AUX_SPI_CNTL0_ENABLE   0x00000800
-#define BCM2835_AUX_SPI_CNTL0_CPHA_IN  0x00000400
+#define BCM2835_AUX_SPI_CNTL0_IN_RISING        0x00000400
 #define BCM2835_AUX_SPI_CNTL0_CLEARFIFO        0x00000200
-#define BCM2835_AUX_SPI_CNTL0_CPHA_OUT 0x00000100
+#define BCM2835_AUX_SPI_CNTL0_OUT_RISING       0x00000100
 #define BCM2835_AUX_SPI_CNTL0_CPOL     0x00000080
 #define BCM2835_AUX_SPI_CNTL0_MSBF_OUT 0x00000040
 #define BCM2835_AUX_SPI_CNTL0_SHIFTLEN 0x0000003F
@@ -92,9 +92,6 @@
 #define BCM2835_AUX_SPI_POLLING_LIMIT_US       30
 #define BCM2835_AUX_SPI_POLLING_JIFFIES                2
 
-#define BCM2835_AUX_SPI_MODE_BITS (SPI_CPOL | SPI_CPHA | SPI_CS_HIGH \
-                                 | SPI_NO_CS)
-
 struct bcm2835aux_spi {
        void __iomem *regs;
        struct clk *clk;
@@ -389,12 +386,12 @@ static int bcm2835aux_spi_prepare_message(struct spi_master *master,
        bs->cntl[1] = BCM2835_AUX_SPI_CNTL1_MSBF_IN;
 
        /* handle all the modes */
-       if (spi->mode & SPI_CPOL)
+       if (spi->mode & SPI_CPOL) {
                bs->cntl[0] |= BCM2835_AUX_SPI_CNTL0_CPOL;
-       if (spi->mode & SPI_CPHA)
-               bs->cntl[0] |= BCM2835_AUX_SPI_CNTL0_CPHA_OUT |
-                              BCM2835_AUX_SPI_CNTL0_CPHA_IN;
-
+               bs->cntl[0] |= BCM2835_AUX_SPI_CNTL0_OUT_RISING;
+       } else {
+               bs->cntl[0] |= BCM2835_AUX_SPI_CNTL0_IN_RISING;
+       }
        bcm2835aux_wr(bs, BCM2835_AUX_SPI_CNTL1, bs->cntl[1]);
        bcm2835aux_wr(bs, BCM2835_AUX_SPI_CNTL0, bs->cntl[0]);
 
@@ -434,7 +431,7 @@ static int bcm2835aux_spi_probe(struct platform_device *pdev)
        }
 
        platform_set_drvdata(pdev, master);
-       master->mode_bits = BCM2835_AUX_SPI_MODE_BITS;
+       master->mode_bits = (SPI_CPOL | SPI_CS_HIGH | SPI_NO_CS);
        master->bits_per_word_mask = SPI_BPW_MASK(8);
        master->num_chipselect = -1;
        master->transfer_one = bcm2835aux_spi_transfer_one;