spi: davinci: Choose correct pre-scaler limit based on SOC

Currently the pre-scaler limit is incorrect. The value differs slightly
for various devices so a single value can't be used. Using the compatible
field select the correct pre-scaler limit.

Add new compatible field value for Keystone devices to support their
unique pre-scaler limit value.

Signed-off-by: Franklin S Cooper Jr <fcooper@ti.com>
Reviewed-by: Sekhar Nori <nsekhar@ti.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/Documentation/devicetree/bindings/spi/spi-davinci.txt b/Documentation/devicetree/bindings/spi/spi-davinci.txt
index 12ecfe9..d1e914a 100644 (file)
--- a/Documentation/devicetree/bindings/spi/spi-davinci.txt
+++ b/Documentation/devicetree/bindings/spi/spi-davinci.txt
@@ -12,6 +12,8 @@ Required properties:
 - compatible:
        - "ti,dm6441-spi" for SPI used similar to that on DM644x SoC family
        - "ti,da830-spi" for SPI used similar to that on DA8xx SoC family
+       - "ti,keystone-spi" for SPI used similar to that on Keystone2 SoC
+               family
 - reg: Offset and length of SPI controller register space
 - num-cs: Number of chip selects. This includes internal as well as
        GPIO chip selects.

diff --git a/drivers/spi/spi-davinci.c b/drivers/spi/spi-davinci.c
index b4605c4..3cf9faa 100644 (file)
--- a/drivers/spi/spi-davinci.c
+++ b/drivers/spi/spi-davinci.c
@@ -139,6 +139,8 @@ struct davinci_spi {
        u32                     (*get_tx)(struct davinci_spi *);
 
        u8                      *bytes_per_word;
+
+       u8                      prescaler_limit;
 };
 
 static struct davinci_spi_config davinci_spi_default_cfg;
@@ -266,7 +268,7 @@ static inline int davinci_spi_get_prescale(struct davinci_spi *dspi,
        /* Subtract 1 to match what will be programmed into SPI register. */
        ret = DIV_ROUND_UP(clk_get_rate(dspi->clk), max_speed_hz) - 1;
 
-       if (ret < 0 || ret > 255)
+       if (ret < dspi->prescaler_limit || ret > 255)
                return -EINVAL;
 
        return ret;
@@ -833,13 +835,40 @@ rx_dma_failed:
 }
 
 #if defined(CONFIG_OF)
+
+/* OF SPI data structure */
+struct davinci_spi_of_data {
+       u8      version;
+       u8      prescaler_limit;
+};
+
+static const struct davinci_spi_of_data dm6441_spi_data = {
+       .version = SPI_VERSION_1,
+       .prescaler_limit = 2,
+};
+
+static const struct davinci_spi_of_data da830_spi_data = {
+       .version = SPI_VERSION_2,
+       .prescaler_limit = 2,
+};
+
+static const struct davinci_spi_of_data keystone_spi_data = {
+       .version = SPI_VERSION_1,
+       .prescaler_limit = 0,
+};
+
 static const struct of_device_id davinci_spi_of_match[] = {
        {
                .compatible = "ti,dm6441-spi",
+               .data = &dm6441_spi_data,
        },
        {
                .compatible = "ti,da830-spi",
-               .data = (void *)SPI_VERSION_2,
+               .data = &da830_spi_data,
+       },
+       {
+               .compatible = "ti,keystone-spi",
+               .data = &keystone_spi_data,
        },
        { },
 };
@@ -858,21 +887,21 @@ static int spi_davinci_get_pdata(struct platform_device *pdev,
                        struct davinci_spi *dspi)
 {
        struct device_node *node = pdev->dev.of_node;
+       struct davinci_spi_of_data *spi_data;
        struct davinci_spi_platform_data *pdata;
        unsigned int num_cs, intr_line = 0;
        const struct of_device_id *match;
 
        pdata = &dspi->pdata;
 
-       pdata->version = SPI_VERSION_1;
        match = of_match_device(davinci_spi_of_match, &pdev->dev);
        if (!match)
                return -ENODEV;
 
-       /* match data has the SPI version number for SPI_VERSION_2 */
-       if (match->data == (void *)SPI_VERSION_2)
-               pdata->version = SPI_VERSION_2;
+       spi_data = (struct davinci_spi_of_data *)match->data;
 
+       pdata->version = spi_data->version;
+       pdata->prescaler_limit = spi_data->prescaler_limit;
        /*
         * default num_cs is 1 and all chipsel are internal to the chip
         * indicated by chip_sel being NULL or cs_gpios being NULL or
@@ -992,7 +1021,7 @@ static int davinci_spi_probe(struct platform_device *pdev)
 
        dspi->bitbang.chipselect = davinci_spi_chipselect;
        dspi->bitbang.setup_transfer = davinci_spi_setup_transfer;
-
+       dspi->prescaler_limit = pdata->prescaler_limit;
        dspi->version = pdata->version;
 
        dspi->bitbang.flags = SPI_NO_CS | SPI_LSB_FIRST | SPI_LOOP;

diff --git a/include/linux/platform_data/spi-davinci.h b/include/linux/platform_data/spi-davinci.h
index 8dc2fa4..f4edcb0 100644 (file)
--- a/include/linux/platform_data/spi-davinci.h
+++ b/include/linux/platform_data/spi-davinci.h
@@ -49,6 +49,7 @@ struct davinci_spi_platform_data {
        u8                      num_chipselect;
        u8                      intr_line;
        u8                      *chip_sel;
+       u8                      prescaler_limit;
        bool                    cshold_bug;
        enum dma_event_q        dma_event_q;
 };