spi: spi-gpio: add SPI_3WIRE support

Add SPI_3WIRE support to spi-gpio controller introducing
set_line_direction function pointer in spi_bitbang data structure.
Spi-gpio controller has been tested using hts221 temp/rh iio sensor
running in 3wire mode and lsm6dsm running in 4wire mode

Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

1 files changed, 16 insertions, 1 deletions

diff --git a/drivers/spi/spi-gpio.c b/drivers/spi/spi-gpio.c
index be68298cbd9c..0626e6e3ea0c 100644
--- a/drivers/spi/spi-gpio.c
+++ b/drivers/spi/spi-gpio.c
@@ -121,7 +121,10 @@ static inline int getmiso(const struct spi_device *spi)
 {
         struct spi_gpio *spi_gpio = spi_to_spi_gpio(spi);
 
-        return !!gpiod_get_value_cansleep(spi_gpio->miso);
+        if (spi->mode & SPI_3WIRE)
+                return !!gpiod_get_value_cansleep(spi_gpio->mosi);
+        else
+                return !!gpiod_get_value_cansleep(spi_gpio->miso);
 }
 
 /*
@@ -250,6 +253,16 @@ static int spi_gpio_setup(struct spi_device *spi)
         return status;
 }
 
+static int spi_gpio_set_direction(struct spi_device *spi, bool output)
+{
+        struct spi_gpio *spi_gpio = spi_to_spi_gpio(spi);
+
+        if (output)
+                return gpiod_direction_output(spi_gpio->mosi, 1);
+        else
+                return gpiod_direction_input(spi_gpio->mosi);
+}
+
 static void spi_gpio_cleanup(struct spi_device *spi)
 {
         spi_bitbang_cleanup(spi);
@@ -395,6 +408,7 @@ static int spi_gpio_probe(struct platform_device *pdev)
                 return status;
 
         master->bits_per_word_mask = SPI_BPW_RANGE_MASK(1, 32);
+        master->mode_bits = SPI_3WIRE | SPI_CPHA | SPI_CPOL;
         master->flags = master_flags;
         master->bus_num = pdev->id;
         /* The master needs to think there is a chipselect even if not connected */
@@ -407,6 +421,7 @@ static int spi_gpio_probe(struct platform_device *pdev)
 
         spi_gpio->bitbang.master = master;
         spi_gpio->bitbang.chipselect = spi_gpio_chipselect;
+        spi_gpio->bitbang.set_line_direction = spi_gpio_set_direction;
 
         if ((master_flags & (SPI_MASTER_NO_TX | SPI_MASTER_NO_RX)) == 0) {
                 spi_gpio->bitbang.txrx_word[SPI_MODE_0] = spi_gpio_txrx_word_mode0;