commit af060b3f72b801962033f75a2fda25fff992796d
author Simon Goldschmidt <simon.k.r.goldschmidt@gmail.com> Tue Sep 04 21:49:44 2018 +0200
committer Mark Brown <broonie@kernel.org> Thu Sep 06 12:09:37 2018 +0100
tree d4c37f8b64d86ef924a7422a0cf278b33c8b3f47
parent 48c29d0d27fbbb4c78d3c14c50067d7e8919ed95

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>

drivers/spi/spi-dw.c

diff --git a/drivers/spi/spi-dw.c b/drivers/spi/spi-dw.c
index 1736612..3e205ab 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;