From: Murali Karicheri <m-karicheri2@xxxxxx> This patch adds ability to configure delay between transmission of words over SPI bus if it's required by SPI slave devices. New optional SPI slave properties: - ti,spi-word-delay : delay between transmission of words (SPIFMTn.WDELAY, SPIDAT1.WDEL) - ti,spi-c2t-delay: Chip-select-active-to-transmit-start delay (SPIDELAY.C2TDELAY) - ti,spi-t2c-delay: Transmit-end-to-chip-select-inactive delay (SPIDELAY.T2CDELAY) - ti,spi-disable-cstimer: disable CS timer (SPIFMTn.DISCSTIMERS). If WDELAY, C2TDELAY, T2CDELAY are configured then delay between transmission of words will be added as following: wdelay = T2CDELAY + WDELAY + C2TDELAY. If "ti,spi-disable-cstimer" is configured: wdelay = WDELAY. Signed-off-by: Murali Karicheri <m-karicheri2@xxxxxx> Signed-off-by: Grygorii Strashko <grygorii.strashko@xxxxxx> --- Changes in v2: - reduced number of new parameters - bindings updated Link on v1: http://www.spinics.net/lists/linux-spi/msg01609.html .../devicetree/bindings/spi/spi-davinci.txt | 50 +++++++++++++++++ drivers/spi/spi-davinci.c | 62 +++++++++++++++++++--- 2 files changed, 105 insertions(+), 7 deletions(-) diff --git a/Documentation/devicetree/bindings/spi/spi-davinci.txt b/Documentation/devicetree/bindings/spi/spi-davinci.txt index f80887b..1c336d4 100644 --- a/Documentation/devicetree/bindings/spi/spi-davinci.txt +++ b/Documentation/devicetree/bindings/spi/spi-davinci.txt @@ -24,6 +24,54 @@ Optional: cs-gpios = <0>, <0>, <0>, <&gpio1 30 0>, <&gpio1 31 0>; where first three are internal CS and last two are GPIO CS. +Optional properties for slave devices: +SPI slave nodes can contain the following properties. +Not all SPI Peripherals from Texas Instruments support this. +Please check SPI peripheral documentation for a device before using these. + +- ti,spi-word-delay : delay between transmission of words + (SPIFMTn.WDELAY, SPIDAT1.WDEL) must be specified in number of SPI module + clock periods. + + delay = WDELAY * SPI_module_clock_period + 2 * SPI_module_clock_period + +- ti,spi-c2t-delay: Chip-select-active-to-transmit-start delay + (SPIDELAY.C2TDELAY) must be specified in number of SPI module + clock periods. if 0 - delay is not applied. + + delay = (C2TDELAY + 2) * SPI_module_clock_period + +- ti,spi-t2c-delay: Transmit-end-to-chip-select-inactive delay + (SPIDELAY.T2CDELAY) must be specified in number of SPI module + clock periods. if 0 - delay is not applied. + + delay = (T2CDELAY + 1) * SPI_module_clock_period + +- ti,spi-disable-cstimer: disable CS timer (SPIFMTn.DISCSTIMERS). Boolean + property that the C2TDELAY and T2CDELAY timers should be disabled. + +Below is timing diagram which shows functional meaning of +"ti,spi-word-delay", "ti,spi-c2t-delay" and "ti,spi-t2c-delay" parameters. + + +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +SPI_CLK | | | | | | | | | | | | | | | | + +----------+ +-+ +-+ +-+ +-+ +---------------------------+ +-+ +-+ +- + +SPI_SOMI/SIMO+-----------------+ +----------- + +----------+ word1 +---------------------------+word2 + +-----------------+ +----------- + WDELAY + <---------> + + + +SPI_CS | | + +----+ +-----------+ + | | | + +-----+-----------------+--------+ +-----+------------ + | | | | | | + + + + | + + + <---> <------> <---> + C2TDELAY T2CDELAY C2TDELAY + Example of a NOR flash slave device (n25q032) connected to DaVinci SPI controller device over the SPI bus. @@ -43,6 +91,8 @@ spi0:spi@20BF0000 { compatible = "st,m25p32"; spi-max-frequency = <25000000>; reg = <0>; + ti,spi-c2t-delay = <8>; + ti,spi-t2c-delay = <8>; partition@0 { label = "u-boot-spl"; diff --git a/drivers/spi/spi-davinci.c b/drivers/spi/spi-davinci.c index 48f1d26..ccadc95 100644 --- a/drivers/spi/spi-davinci.c +++ b/drivers/spi/spi-davinci.c @@ -65,6 +65,7 @@ /* SPIDAT1 (upper 16 bit defines) */ #define SPIDAT1_CSHOLD_MASK BIT(12) +#define SPIDAT1_WDEL BIT(10) /* SPIGCR1 */ #define SPIGCR1_CLKMOD_MASK BIT(1) @@ -209,6 +210,7 @@ static void davinci_spi_chipselect(struct spi_device *spi, int value) { struct davinci_spi *dspi; struct davinci_spi_platform_data *pdata; + struct davinci_spi_config *spicfg = spi->controller_data; u8 chip_sel = spi->chip_select; u16 spidat1 = CS_DEFAULT; bool gpio_chipsel = false; @@ -223,6 +225,10 @@ static void davinci_spi_chipselect(struct spi_device *spi, int value) gpio = spi->cs_gpio; } + /* program delay transfers if tx_delay is non zero */ + if (spicfg->wdelay) + spidat1 |= SPIDAT1_WDEL; + /* * Board specific chip select logic decides the polarity and cs * line for the controller @@ -237,9 +243,9 @@ static void davinci_spi_chipselect(struct spi_device *spi, int value) spidat1 |= SPIDAT1_CSHOLD_MASK; spidat1 &= ~(0x1 << chip_sel); } - - iowrite16(spidat1, dspi->base + SPIDAT1 + 2); } + + iowrite16(spidat1, dspi->base + SPIDAT1 + 2); } /** @@ -285,7 +291,7 @@ static int davinci_spi_setup_transfer(struct spi_device *spi, int prescale; dspi = spi_master_get_devdata(spi->master); - spicfg = (struct davinci_spi_config *)spi->controller_data; + spicfg = spi->controller_data; if (!spicfg) spicfg = &davinci_spi_default_cfg; @@ -333,6 +339,14 @@ static int davinci_spi_setup_transfer(struct spi_device *spi, spifmt |= SPIFMT_PHASE_MASK; /* + * Assume wdelay is used only on SPI peripherals that has this field + * in SPIFMTn register and when it's configured from board file or DT. + */ + if (spicfg->wdelay) + spifmt |= ((spicfg->wdelay << SPIFMT_WDELAY_SHIFT) + & SPIFMT_WDELAY_MASK); + + /* * Version 1 hardware supports two basic SPI modes: * - Standard SPI mode uses 4 pins, with chipselect * - 3 pin SPI is a 4 pin variant without CS (SPI_NO_CS) @@ -349,9 +363,6 @@ static int davinci_spi_setup_transfer(struct spi_device *spi, u32 delay = 0; - spifmt |= ((spicfg->wdelay << SPIFMT_WDELAY_SHIFT) - & SPIFMT_WDELAY_MASK); - if (spicfg->odd_parity) spifmt |= SPIFMT_ODD_PARITY_MASK; @@ -383,6 +394,37 @@ static int davinci_spi_setup_transfer(struct spi_device *spi, return 0; } +static int davinci_spi_of_setup(struct spi_device *spi) +{ + struct davinci_spi_config *spicfg = spi->controller_data; + struct device_node *np = spi->dev.of_node; + u32 prop; + int len; + + if (spicfg == NULL && np) { + spicfg = kzalloc(sizeof(*spicfg), GFP_KERNEL); + if (!spicfg) + return -ENOMEM; + *spicfg = davinci_spi_default_cfg; + /* override with dt configured values */ + if (!of_property_read_u32(np, + "ti,spi-word-delay", &prop)) + spicfg->wdelay = (u8)prop; + if (of_find_property(np, + "ti,spi-disable-cstimer", &len)) + spicfg->timer_disable = 1; + if (!of_property_read_u32(np, + "ti,spi-c2t-delay", &prop)) + spicfg->c2tdelay = (u8)prop; + if (!of_property_read_u32(np, + "ti,spi-t2c-delay", &prop)) + spicfg->t2cdelay = (u8)prop; + spi->controller_data = spicfg; + } + + return 0; +} + /** * davinci_spi_setup - This functions will set default transfer method * @spi: spi device on which data transfer to be done @@ -436,11 +478,17 @@ static int davinci_spi_setup(struct spi_device *spi) else clear_io_bits(dspi->base + SPIGCR1, SPIGCR1_LOOPBACK_MASK); - return retval; + return davinci_spi_of_setup(spi); } static void davinci_spi_cleanup(struct spi_device *spi) { + struct davinci_spi_config *spicfg = spi->controller_data; + + spi->controller_data = NULL; + if (spi->dev.of_node) + kfree(spicfg); + if (spi->cs_gpio >= 0) gpio_free(spi->cs_gpio); } -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html