spi: soft_spi: Add support for SPI_3WIRE

When 3-wire mode is claimed on the bus, use the MOSI (output) pin to
receive data. In this mode, since the transfer can only be either TX
or RX, return -EINVAL if both are required at the same time.

Signed-off-by: Hironori KIKUCHI <kikuchan98@gmail.com>

diff --git a/drivers/spi/soft_spi.c b/drivers/spi/soft_spi.c
index a8ec2f4..50bd7be 100644 (file)
--- a/drivers/spi/soft_spi.c
+++ b/drivers/spi/soft_spi.c
@@ -124,8 +124,19 @@ static int soft_spi_xfer(struct udevice *dev, unsigned int bitlen,
        u8              *rxd = din;
        int             cpha = !!(priv->mode & SPI_CPHA);
        int             cidle = !!(priv->mode & SPI_CPOL);
+       int             txrx = plat->flags;
        unsigned int    j;
 
+       if (priv->mode & SPI_3WIRE) {
+               if (txd && rxd)
+                       return -EINVAL;
+
+               txrx = txd ? SPI_MASTER_NO_RX : SPI_MASTER_NO_TX;
+               dm_gpio_set_dir_flags(&plat->mosi,
+                                     txd ? GPIOD_IS_OUT | GPIOD_IS_OUT_ACTIVE :
+                                           GPIOD_IS_IN | GPIOD_PULL_UP);
+       }
+
        debug("spi_xfer: slave %s:%s dout %08X din %08X bitlen %u\n",
              dev->parent->name, dev->name, *(uint *)txd, *(uint *)rxd,
              bitlen);
@@ -160,7 +171,7 @@ static int soft_spi_xfer(struct udevice *dev, unsigned int bitlen,
                 */
                if (cpha)
                        soft_spi_scl(dev, !cidle);
-               if ((plat->flags & SPI_MASTER_NO_TX) == 0)
+               if ((txrx & SPI_MASTER_NO_TX) == 0)
                        soft_spi_sda(dev, !!(tmpdout & 0x80));
                udelay(plat->spi_delay_us);
 
@@ -174,8 +185,10 @@ static int soft_spi_xfer(struct udevice *dev, unsigned int bitlen,
                else
                        soft_spi_scl(dev, cidle);
                tmpdin  <<= 1;
-               if ((plat->flags & SPI_MASTER_NO_RX) == 0)
-                       tmpdin  |= dm_gpio_get_value(&plat->miso);
+               if ((txrx & SPI_MASTER_NO_RX) == 0)
+                       tmpdin |= dm_gpio_get_value((priv->mode & SPI_3WIRE) ?
+                                                           &plat->mosi :
+                                                           &plat->miso);
                tmpdout <<= 1;
                udelay(plat->spi_delay_us);