[2/2] spi: davinci: add support to configure gpio cs through dt

Message ID 1406827995-30913-3-git-send-email-grygorii.strashko@ti.com
State New
Headers show

Commit Message

Grygorii Strashko July 31, 2014, 5:33 p.m.
From: Murali Karicheri <m-karicheri2@ti.com>

Currently driver supports only configuration of GPIO CS through
platform data. This patch enhances the driver to configure GPIO
CS through DT. Also update the DT binding documentation to
reflect the availability of cs-gpios.

Signed-off-by: Murali Karicheri <m-karicheri2@ti.com>
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
---
 .../devicetree/bindings/spi/spi-davinci.txt        |    9 ++-
 drivers/spi/spi-davinci.c                          |   59 +++++++++++++++++---
 2 files changed, 59 insertions(+), 9 deletions(-)

Comments

Mark Brown July 31, 2014, 7:35 p.m. | #1
On Thu, Jul 31, 2014 at 08:33:15PM +0300, Grygorii Strashko wrote:

> +	if (np && master->cs_gpios != NULL && spi->cs_gpio >= 0) {
> +		/* SPI core parse and update master->cs_gpio */
>  		gpio_chipsel = true;
> +		gpio = spi->cs_gpio;
> +	} else if (pdata->chip_sel &&
> +		   chip_sel < pdata->num_chipselect &&
> +		   pdata->chip_sel[chip_sel] != SPI_INTERN_CS) {
> +		/* platform data defines chip_sel */
> +		gpio_chipsel = true;
> +		gpio = pdata->chip_sel[chip_sel];
> +	}

This would all be a lot simpler and more direct if you were to arrange
to use cs_gpio in the struct spi_device, and move you closer to
converting to use more of the core functionality.

> +		if (np && (master->cs_gpios != NULL) && (spi->cs_gpio >= 0)) {
> +			retval =
> +				gpio_request(spi->cs_gpio, dev_name(&spi->dev));
> +			if (retval) {
> +				dev_err(&spi->dev,
> +					"GPIO %d request failed\n",
> +					spi->cs_gpio);
> +				return -ENODEV;
> +			}
> +			gpio_direction_output(spi->cs_gpio,
> +					      !(spi->mode & SPI_CS_HIGH));
> +			internal_cs = false;

It's much better to use gpio_request_one() rather than using
gpio_request(), it's one function apart from anything else.  The above
is also discarding the return code of gpio_request() meaning it's broken
for deferred probe.  The error code should also appear in the error
message.
Grygorii Strashko Aug. 1, 2014, 3:28 p.m. | #2
Hi Mark,
On 07/31/2014 10:35 PM, Mark Brown wrote:
> On Thu, Jul 31, 2014 at 08:33:15PM +0300, Grygorii Strashko wrote:
> 
>> +	if (np && master->cs_gpios != NULL && spi->cs_gpio >= 0) {
>> +		/* SPI core parse and update master->cs_gpio */
>>   		gpio_chipsel = true;
>> +		gpio = spi->cs_gpio;
>> +	} else if (pdata->chip_sel &&
>> +		   chip_sel < pdata->num_chipselect &&
>> +		   pdata->chip_sel[chip_sel] != SPI_INTERN_CS) {
>> +		/* platform data defines chip_sel */
>> +		gpio_chipsel = true;
>> +		gpio = pdata->chip_sel[chip_sel];
>> +	}
> 
> This would all be a lot simpler and more direct if you were to arrange
> to use cs_gpio in the struct spi_device, and move you closer to
> converting to use more of the core functionality.

Unfortunately, I'm not sure this is good idea, because this part of
code is used by Davinci arch which is non-DT platform.
As result, this code was kept mostly unchanged.

I can try to rework it, but I'd like to do it as standalone patch.
Is it ok for you?

> 
>> +		if (np && (master->cs_gpios != NULL) && (spi->cs_gpio >= 0)) {
>> +			retval =
>> +				gpio_request(spi->cs_gpio, dev_name(&spi->dev));
>> +			if (retval) {
>> +				dev_err(&spi->dev,
>> +					"GPIO %d request failed\n",
>> +					spi->cs_gpio);
>> +				return -ENODEV;
>> +			}
>> +			gpio_direction_output(spi->cs_gpio,
>> +					      !(spi->mode & SPI_CS_HIGH));
>> +			internal_cs = false;
> 
> It's much better to use gpio_request_one() rather than using
> gpio_request(), it's one function apart from anything else.  The above
> is also discarding the return code of gpio_request() meaning it's broken
> for deferred probe.  The error code should also appear in the error
> message.
> 
Thanks, will update.

Regards,
-grygorii
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diff --git a/Documentation/devicetree/bindings/spi/spi-davinci.txt b/Documentation/devicetree/bindings/spi/spi-davinci.txt
index 6d0ac8d..f80887b 100644
--- a/Documentation/devicetree/bindings/spi/spi-davinci.txt
+++ b/Documentation/devicetree/bindings/spi/spi-davinci.txt
@@ -8,7 +8,8 @@  Required properties:
 	- "ti,dm6441-spi" for SPI used similar to that on DM644x SoC family
 	- "ti,da830-spi" for SPI used similar to that on DA8xx SoC family
 - reg: Offset and length of SPI controller register space
-- num-cs: Number of chip selects
+- num-cs: Number of chip selects. This includes internal as well as
+	GPIO chip selects.
 - ti,davinci-spi-intr-line: interrupt line used to connect the SPI
 	IP to the interrupt controller within the SoC. Possible values
 	are 0 and 1. Manual says one of the two possible interrupt
@@ -17,6 +18,12 @@  Required properties:
 - interrupts: interrupt number mapped to CPU.
 - clocks: spi clk phandle
 
+Optional:
+- cs-gpios: gpio chip selects
+	For example to have 3 internal CS and 2 GPIO CS, user could define
+	cs-gpios = <0>, <0>, <0>, <&gpio1 30 0>, <&gpio1 31 0>;
+	where first three are internal CS and last two are GPIO CS.
+
 Example of a NOR flash slave device (n25q032) connected to DaVinci
 SPI controller device over the SPI bus.
 
diff --git a/drivers/spi/spi-davinci.c b/drivers/spi/spi-davinci.c
index 2477af4..6aa04d1 100644
--- a/drivers/spi/spi-davinci.c
+++ b/drivers/spi/spi-davinci.c
@@ -30,6 +30,7 @@ 
 #include <linux/edma.h>
 #include <linux/of.h>
 #include <linux/of_device.h>
+#include <linux/of_gpio.h>
 #include <linux/spi/spi.h>
 #include <linux/spi/spi_bitbang.h>
 #include <linux/slab.h>
@@ -207,17 +208,28 @@  static inline void clear_io_bits(void __iomem *addr, u32 bits)
 static void davinci_spi_chipselect(struct spi_device *spi, int value)
 {
 	struct davinci_spi *dspi;
+	struct device_node *np = spi->dev.of_node;
 	struct davinci_spi_platform_data *pdata;
+	struct spi_master *master = spi->master;
 	u8 chip_sel = spi->chip_select;
 	u16 spidat1 = CS_DEFAULT;
 	bool gpio_chipsel = false;
+	int gpio;
 
 	dspi = spi_master_get_devdata(spi->master);
 	pdata = &dspi->pdata;
 
-	if (pdata->chip_sel && chip_sel < pdata->num_chipselect &&
-				pdata->chip_sel[chip_sel] != SPI_INTERN_CS)
+	if (np && master->cs_gpios != NULL && spi->cs_gpio >= 0) {
+		/* SPI core parse and update master->cs_gpio */
 		gpio_chipsel = true;
+		gpio = spi->cs_gpio;
+	} else if (pdata->chip_sel &&
+		   chip_sel < pdata->num_chipselect &&
+		   pdata->chip_sel[chip_sel] != SPI_INTERN_CS) {
+		/* platform data defines chip_sel */
+		gpio_chipsel = true;
+		gpio = pdata->chip_sel[chip_sel];
+	}
 
 	/*
 	 * Board specific chip select logic decides the polarity and cs
@@ -225,9 +237,9 @@  static void davinci_spi_chipselect(struct spi_device *spi, int value)
 	 */
 	if (gpio_chipsel) {
 		if (value == BITBANG_CS_ACTIVE)
-			gpio_set_value(pdata->chip_sel[chip_sel], 0);
+			gpio_set_value(gpio, 0);
 		else
-			gpio_set_value(pdata->chip_sel[chip_sel], 1);
+			gpio_set_value(gpio, 1);
 	} else {
 		if (value == BITBANG_CS_ACTIVE) {
 			spidat1 |= SPIDAT1_CSHOLD_MASK;
@@ -390,17 +402,36 @@  static int davinci_spi_setup(struct spi_device *spi)
 	int retval = 0;
 	struct davinci_spi *dspi;
 	struct davinci_spi_platform_data *pdata;
+	struct spi_master *master = spi->master;
+	struct device_node *np = spi->dev.of_node;
+	bool internal_cs = true;
 
 	dspi = spi_master_get_devdata(spi->master);
 	pdata = &dspi->pdata;
 
 	if (!(spi->mode & SPI_NO_CS)) {
-		if ((pdata->chip_sel == NULL) ||
-		    (pdata->chip_sel[spi->chip_select] == SPI_INTERN_CS))
-			set_io_bits(dspi->base + SPIPC0, 1 << spi->chip_select);
-
+		if (np && (master->cs_gpios != NULL) && (spi->cs_gpio >= 0)) {
+			retval =
+				gpio_request(spi->cs_gpio, dev_name(&spi->dev));
+			if (retval) {
+				dev_err(&spi->dev,
+					"GPIO %d request failed\n",
+					spi->cs_gpio);
+				return -ENODEV;
+			}
+			gpio_direction_output(spi->cs_gpio,
+					      !(spi->mode & SPI_CS_HIGH));
+			internal_cs = false;
+		} else if (pdata->chip_sel &&
+			   spi->chip_select < pdata->num_chipselect &&
+			   pdata->chip_sel[spi->chip_select] != SPI_INTERN_CS) {
+			internal_cs = false;
+		}
 	}
 
+	if (internal_cs)
+		set_io_bits(dspi->base + SPIPC0, 1 << spi->chip_select);
+
 	if (spi->mode & SPI_READY)
 		set_io_bits(dspi->base + SPIPC0, SPIPC0_SPIENA_MASK);
 
@@ -412,6 +443,15 @@  static int davinci_spi_setup(struct spi_device *spi)
 	return retval;
 }
 
+static void davinci_spi_cleanup(struct spi_device *spi)
+{
+	struct spi_master *master = spi->master;
+	struct device_node *np = spi->dev.of_node;
+
+	if (np && (master->cs_gpios != NULL) && (spi->cs_gpio >= 0))
+		gpio_free(spi->cs_gpio);
+}
+
 static int davinci_spi_check_error(struct davinci_spi *dspi, int int_status)
 {
 	struct device *sdev = dspi->bitbang.master->dev.parent;
@@ -810,6 +850,8 @@  static int spi_davinci_get_pdata(struct platform_device *pdev,
 
 	/*
 	 * default num_cs is 1 and all chipsel are internal to the chip
+	 * indicated by chip_sel being NULL or cs_gpios being NULL or
+	 * set to -ENOENT. num-cs includes internal as well as gpios.
 	 * indicated by chip_sel being NULL. GPIO based CS is not
 	 * supported yet in DT bindings.
 	 */
@@ -921,6 +963,7 @@  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;