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spi: davinci: add support for adding delay between word's transmissions

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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 property:
- ti,spi-word-delay : delay between transmission of words
	(SPIFMTn.WDELAY, SPIDAT1.WDEL)

Signed-off-by: Murali Karicheri <m-karicheri2@ti.com>
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Murali Karicheri 2014-09-16 14:25:05 +03:00 committed by Mark Brown
parent 6e7488f8f6
commit 365a7bb32e
2 changed files with 78 additions and 7 deletions
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30
Documentation/devicetree/bindings/spi/spi-davinci.txt
View File

@ -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";

55
drivers/spi/spi-davinci.c
View File

@ -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;
@ -332,6 +338,14 @@ static int davinci_spi_setup_transfer(struct spi_device *spi,
if (!(spi->mode & SPI_CPHA))
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
@ -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
@ -433,7 +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)
@ -947,6 +987,7 @@ static int davinci_spi_probe(struct platform_device *pdev)
master->num_chipselect = pdata->num_chipselect;
master->bits_per_word_mask = SPI_BPW_RANGE_MASK(2, 16);
master->setup = davinci_spi_setup;
master->cleanup = davinci_spi_cleanup;
dspi->bitbang.chipselect = davinci_spi_chipselect;
dspi->bitbang.setup_transfer = davinci_spi_setup_transfer;