spi: dw: introduce support of loopback mode

For testing purposes it's good to have a loopback mode enabled. The patch adds
necessary bits for that.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c
index e2f7c5c..7064cd0 100644 (file)
--- a/drivers/spi/spi-dw.c
+++ b/drivers/spi/spi-dw.c
@@ -591,6 +591,9 @@ static int dw_spi_setup(struct spi_device *spi)
                        | (spi->mode  << SPI_MODE_OFFSET)
                        | (chip->tmode << SPI_TMOD_OFFSET);
 
+       if (spi->mode & SPI_LOOP)
+               chip->cr0 |= 1 << SPI_SRL_OFFSET;
+
        if (gpio_is_valid(spi->cs_gpio)) {
                ret = gpio_direction_output(spi->cs_gpio,
                                !(spi->mode & SPI_CS_HIGH));
@@ -652,7 +655,7 @@ int dw_spi_add_host(struct device *dev, struct dw_spi *dws)
                goto err_free_master;
        }
 
-       master->mode_bits = SPI_CPOL | SPI_CPHA;
+       master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_LOOP;
        master->bits_per_word_mask = SPI_BPW_MASK(8) | SPI_BPW_MASK(16);
        master->bus_num = dws->bus_num;
        master->num_chipselect = dws->num_cs;