From bba732d86694f7217a41e83a2c1deb42ed9aa7fd Mon Sep 17 00:00:00 2001 From: Franklin S Cooper Jr Date: Wed, 22 Jul 2015 07:32:21 -0500 Subject: spi: davinci: Set prescale value based on register value Within davinci_spi_get_prescale() the prescale has two meanings. First one being the calculated prescale value and then at the end translates it to the prescale value that will be written to the SPI register. At first glance this can be confusing especially when comparing the minimum prescale value against what is seen in the TRM. To simplify things make it clear that the calculated prescale value will always be based on the value that will be written into the SPI register. Signed-off-by: Franklin S Cooper Jr Signed-off-by: Mark Brown --- drivers/spi/spi-davinci.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) (limited to 'drivers/spi/spi-davinci.c') diff --git a/drivers/spi/spi-davinci.c b/drivers/spi/spi-davinci.c index 987afebea093..b4605c4158f4 100644 --- a/drivers/spi/spi-davinci.c +++ b/drivers/spi/spi-davinci.c @@ -255,7 +255,7 @@ static void davinci_spi_chipselect(struct spi_device *spi, int value) * This function calculates the prescale value that generates a clock rate * less than or equal to the specified maximum. * - * Returns: calculated prescale - 1 for easy programming into SPI registers + * Returns: calculated prescale value for easy programming into SPI registers * or negative error number if valid prescalar cannot be updated. */ static inline int davinci_spi_get_prescale(struct davinci_spi *dspi, @@ -263,12 +263,13 @@ static inline int davinci_spi_get_prescale(struct davinci_spi *dspi, { int ret; - ret = DIV_ROUND_UP(clk_get_rate(dspi->clk), max_speed_hz); + /* 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 < 1 || ret > 256) + if (ret < 0 || ret > 255) return -EINVAL; - return ret - 1; + return ret; } /** -- cgit v1.2.3 From fa466c91970a0207d9384016cc7884a7f61834b6 Mon Sep 17 00:00:00 2001 From: Franklin S Cooper Jr Date: Wed, 22 Jul 2015 07:32:22 -0500 Subject: 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 Reviewed-by: Sekhar Nori Signed-off-by: Mark Brown --- .../devicetree/bindings/spi/spi-davinci.txt | 2 + drivers/spi/spi-davinci.c | 43 ++++++++++++++++++---- include/linux/platform_data/spi-davinci.h | 1 + 3 files changed, 39 insertions(+), 7 deletions(-) (limited to 'drivers/spi/spi-davinci.c') diff --git a/Documentation/devicetree/bindings/spi/spi-davinci.txt b/Documentation/devicetree/bindings/spi/spi-davinci.txt index 12ecfe9e3599..d1e914adcf6e 100644 --- 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 b4605c4158f4..3cf9faa6cc3f 100644 --- 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 8dc2fa47a2aa..f4edcb03c40c 100644 --- 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; }; -- cgit v1.2.3