[PATCH V2 3/4] spi: lpspi: Let watermark change with send data length

[Clark Wang]

Configure watermark to change with the length of the sent data.
Support LPSPI sending message shorter than tx/rxfifosize.

Signed-off-by: Clark Wang <xiaoning.w...@nxp.com>
---
Change log:
V2:
 - No change.
---
 drivers/spi/spi-fsl-lpspi.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/spi/spi-fsl-lpspi.c b/drivers/spi/spi-fsl-lpspi.c
index cbf165e7bd17..08dcc3c22e88 100644
--- a/drivers/spi/spi-fsl-lpspi.c
+++ b/drivers/spi/spi-fsl-lpspi.c
@@ -89,6 +89,7 @@ struct fsl_lpspi_data {
        void (*rx)(struct fsl_lpspi_data *);
 
        u32 remain;
+       u8 watermark;
        u8 txfifosize;
        u8 rxfifosize;
 
@@ -235,7 +236,7 @@ static void fsl_lpspi_set_watermark(struct fsl_lpspi_data 
*fsl_lpspi)
 {
        u32 temp;
 
-       temp = fsl_lpspi->txfifosize >> 1 | (fsl_lpspi->rxfifosize >> 1) << 16;
+       temp = fsl_lpspi->watermark >> 1 | (fsl_lpspi->watermark >> 1) << 16;
 
        writel(temp, fsl_lpspi->base + IMX7ULP_FCR);
 
@@ -261,7 +262,8 @@ static int fsl_lpspi_set_bitrate(struct fsl_lpspi_data 
*fsl_lpspi)
        if (prescale == 8 && scldiv >= 256)
                return -EINVAL;
 
-       writel(scldiv, fsl_lpspi->base + IMX7ULP_CCR);
+       writel(scldiv | (scldiv << 8) | ((scldiv >> 1) << 16),
+                                       fsl_lpspi->base + IMX7ULP_CCR);
 
        dev_dbg(fsl_lpspi->dev, "perclk=%d, speed=%d, prescale =%d, 
scldiv=%d\n",
                perclk_rate, config.speed_hz, prescale, scldiv);
@@ -329,6 +331,11 @@ static void fsl_lpspi_setup_transfer(struct spi_device 
*spi,
                fsl_lpspi->tx = fsl_lpspi_buf_tx_u32;
        }
 
+       if (t->len <= fsl_lpspi->txfifosize)
+               fsl_lpspi->watermark = t->len;
+       else
+               fsl_lpspi->watermark = fsl_lpspi->txfifosize;
+
        fsl_lpspi_config(fsl_lpspi);
 }
 
-- 
2.17.1