spi: spi-fsl-dspi: Simplify bytes_per_word gymnastics

Reduce the if-then-else-if-then-else sequence to:
 - a simple division in the case of bytes_per_word calculation
 - a memcpy command with a variable size. The semantics of larger-than-8
   xfer->bits_per_word is that those words are to be interpreted and
   transmitted in CPU native endianness.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://lore.kernel.org/r/20200304220044.11193-2-olteanv@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/drivers/spi/spi-fsl-dspi.c b/drivers/spi/spi-fsl-dspi.c
index c357c32..896d7a0 100644 (file)
--- a/drivers/spi/spi-fsl-dspi.c
+++ b/drivers/spi/spi-fsl-dspi.c
@@ -252,12 +252,7 @@ static u32 dspi_pop_tx(struct fsl_dspi *dspi)
        u32 txdata = 0;
 
        if (dspi->tx) {
-               if (dspi->bytes_per_word == 1)
-                       txdata = *(u8 *)dspi->tx;
-               else if (dspi->bytes_per_word == 2)
-                       txdata = *(u16 *)dspi->tx;
-               else  /* dspi->bytes_per_word == 4 */
-                       txdata = *(u32 *)dspi->tx;
+               memcpy(&txdata, dspi->tx, dspi->bytes_per_word);
                dspi->tx += dspi->bytes_per_word;
        }
        dspi->len -= dspi->bytes_per_word;
@@ -284,12 +279,7 @@ static void dspi_push_rx(struct fsl_dspi *dspi, u32 rxdata)
        /* Mask off undefined bits */
        rxdata &= (1 << dspi->bits_per_word) - 1;
 
-       if (dspi->bytes_per_word == 1)
-               *(u8 *)dspi->rx = rxdata;
-       else if (dspi->bytes_per_word == 2)
-               *(u16 *)dspi->rx = rxdata;
-       else /* dspi->bytes_per_word == 4 */
-               *(u32 *)dspi->rx = rxdata;
+       memcpy(dspi->rx, &rxdata, dspi->bytes_per_word);
        dspi->rx += dspi->bytes_per_word;
 }
 
@@ -814,12 +804,7 @@ static int dspi_transfer_one_message(struct spi_controller *ctlr,
                dspi->progress = 0;
                /* Validated transfer specific frame size (defaults applied) */
                dspi->bits_per_word = transfer->bits_per_word;
-               if (transfer->bits_per_word <= 8)
-                       dspi->bytes_per_word = 1;
-               else if (transfer->bits_per_word <= 16)
-                       dspi->bytes_per_word = 2;
-               else
-                       dspi->bytes_per_word = 4;
+               dspi->bytes_per_word = DIV_ROUND_UP(dspi->bits_per_word, 8);
 
                regmap_update_bits(dspi->regmap, SPI_MCR,
                                   SPI_MCR_CLR_TXF | SPI_MCR_CLR_RXF,