spi: dw: support 4-16 bits per word

The spi-dw driver currently only supports 8 or 16 bits per word.

Since the hardware supports 4-16 bits per word, adapt the driver
to also support this.

Tested on socfpga cyclone5 with a 9-bit SPI display.

Signed-off-by: Simon Goldschmidt <simon.k.r.goldschmidt@gmail.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

1 files changed, 5 insertions, 10 deletions

diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c
index 1736612ee86b..3e205ab60cd4 100644
--- a/drivers/spi/spi-dw.c
+++ b/drivers/spi/spi-dw.c
@@ -308,15 +308,10 @@ static int dw_spi_transfer_one(struct spi_controller *master,
                 dws->current_freq = transfer->speed_hz;
                 spi_set_clk(dws, chip->clk_div);
         }
-        if (transfer->bits_per_word == 8) {
-                dws->n_bytes = 1;
-                dws->dma_width = 1;
-        } else if (transfer->bits_per_word == 16) {
-                dws->n_bytes = 2;
-                dws->dma_width = 2;
-        } else {
-                return -EINVAL;
-        }
+
+        dws->n_bytes = DIV_ROUND_UP(transfer->bits_per_word, BITS_PER_BYTE);
+        dws->dma_width = DIV_ROUND_UP(transfer->bits_per_word, BITS_PER_BYTE);
+
         /* Default SPI mode is SCPOL = 0, SCPH = 0 */
         cr0 = (transfer->bits_per_word - 1)
                 | (chip->type << SPI_FRF_OFFSET)
@@ -496,7 +491,7 @@ int dw_spi_add_host(struct device *dev, struct dw_spi *dws)
         }
 
         master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_LOOP;
-        master->bits_per_word_mask = SPI_BPW_MASK(8) | SPI_BPW_MASK(16);
+        master->bits_per_word_mask =  SPI_BPW_RANGE_MASK(4, 16);
         master->bus_num = dws->bus_num;
         master->num_chipselect = dws->num_cs;
         master->setup = dw_spi_setup;