From: Murali Karicheri m-kariche...@ti.com
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-kariche...@ti.com
Signed-off-by: Grygorii Strashko grygorii.stras...@ti.com
---
Rebased on top of:
spi.git/for-next +
[PATCH] spi: davinci: remove empty function davinci_spi_cleanup
http://www.spinics.net/lists/arm-kernel/msg362811.html
v3:
http://www.spinics.net/lists/devicetree/msg49141.html
v2:
http://www.spinics.net/lists/devicetree/msg48514.html
v1:
http://www.spinics.net/lists/linux-spi/msg01609.html
.../devicetree/bindings/spi/spi-davinci.txt| 30
drivers/spi/spi-davinci.c | 55 +++---
2 files changed, 78 insertions(+), 7 deletions(-)
diff --git a/Documentation/devicetree/bindings/spi/spi-davinci.txt
b/Documentation/devicetree/bindings/spi/spi-davinci.txt
index f80887b..12ecfe9 100644
--- a/Documentation/devicetree/bindings/spi/spi-davinci.txt
+++ b/Documentation/devicetree/bindings/spi/spi-davinci.txt
@@ -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@20BF {
compatible = st,m25p32;
spi-max-frequency = 2500;
reg = 0;
+ ti,spi-wdelay = 8;
partition@0 {
label = u-boot-spl;
diff --git a/drivers/spi/spi-davinci.c b/drivers/spi/spi-davinci.c
index 134fb6e..ada3891 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_MASKBIT(12)
+#define SPIDAT1_WDEL BIT(10)
/* SPIGCR1 */
#define SPIGCR1_CLKMOD_MASKBIT(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)
