[PATCH v3] spi: davinci: add support for adding delay between word's transmissions

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[PATCH v3] spi: davinci: add support for adding delay between word's transmissions

Grygorii Strashko
From: Murali Karicheri <[hidden email]>

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

Signed-off-by: Murali Karicheri <[hidden email]>
Signed-off-by: Grygorii Strashko <[hidden email]>
---
Changes in v3:
- removed C2TDELAY, T2CDELAY parameters

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                          | 50 +++++++++++++++++++---
 2 files changed, 73 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@20BF0000 {
  compatible = "st,m25p32";
  spi-max-frequency = <25000000>;
  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 d493507..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_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)
--
1.9.1

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Re: [PATCH v3] spi: davinci: add support for adding delay between word's transmissions

Mark Brown
On Fri, Sep 12, 2014 at 06:48:12PM +0300, Grygorii Strashko wrote:
> From: Murali Karicheri <[hidden email]>
>
> This patch adds ability to configure delay between transmission of
> words over SPI bus if it's required by SPI slave devices.

This is fine but it doesn't appear to apply against current code.  Can
you please check and resend?

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Re: [PATCH v3] spi: davinci: add support for adding delay between word's transmissions

Grygorii Strashko
On 09/13/2014 07:06 PM, Mark Brown wrote:
> On Fri, Sep 12, 2014 at 06:48:12PM +0300, Grygorii Strashko wrote:
>> From: Murali Karicheri <[hidden email]>
>>
>> This patch adds ability to configure delay between transmission of
>> words over SPI bus if it's required by SPI slave devices.
>
> This is fine but it doesn't appear to apply against current code.  Can
> you please check and resend?
>

This one should be applied without conflicts on top of
git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git
branch: for-next

since you've applied the patch:
"[PATCH] spi: davinci: request cs_gpio's from probe"
http://www.spinics.net/lists/linux-spi/msg01811.html

I have to mention about this dependency, sorry for that.

Regards,
-grygorii

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Re: [PATCH v3] spi: davinci: add support for adding delay between word's transmissions

Mark Brown
On Mon, Sep 15, 2014 at 04:06:49PM +0300, Grygorii Strashko wrote:
> On 09/13/2014 07:06 PM, Mark Brown wrote:

> > This is fine but it doesn't appear to apply against current code.  Can
> > you please check and resend?

> This one should be applied without conflicts on top of
> git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git
> branch: for-next

> since you've applied the patch:
> "[PATCH] spi: davinci: request cs_gpio's from probe"
> http://www.spinics.net/lists/linux-spi/msg01811.html

> I have to mention about this dependency, sorry for that.

Please resend then as I asked.

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