@@ -1,5 +1,10 @@
Davinci SPI controller device bindings
+Links on DM:
+Keystone 2 - http://www.ti.com/lit/ug/sprugp2a/sprugp2a.pdf
+dm644x - http://www.ti.com/lit/ug/sprue32a/sprue32a.pdf
+OMAP-L138/da830 - http://www.ti.com/lit/ug/spruh77a/spruh77a.pdf
+
Required properties:
- #address-cells: number of cells required to define a chip select
address on the SPI bus. Should be set to 1.
@@ -24,6 +29,30 @@ 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-wdelay : 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
+
+Below is timing diagram which shows functional meaning of
+"ti,spi-wdelay" parameter.
+
+ +-+ +-+ +-+ +-+ +-+ +-+ +-+ +-+
+SPI_CLK | | | | | | | | | | | | | | | |
+ +----------+ +-+ +-+ +-+ +-+ +---------------------------+ +-+ +-+ +-
+
+SPI_SOMI/SIMO+-----------------+ +-----------
+ +----------+ word1 +---------------------------+word2
+ +-----------------+ +-----------
+ WDELAY
+ <-------------------------->
+
Example of a NOR flash slave device (n25q032) connected to DaVinci
SPI controller device over the SPI bus.
@@ -43,6 +72,7 @@ spi0:spi@20BF0000 {
compatible = "st,m25p32";
spi-max-frequency = <25000000>;
reg = <0>;
+ ti,spi-wdelay = <8>;
partition@0 {
label = "u-boot-spl";
@@ -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 +394,26 @@ 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;
+
+ 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-wdelay", &prop))
+ spicfg->wdelay = (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
@@ -433,11 +464,16 @@ 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);
}
static int davinci_spi_check_error(struct davinci_spi *dspi, int int_status)