[2/3] spi: s3c64xx: Added provision for dedicated cs pin

Commit Message

[e-mail] April 22, 2013, 7:09 a.m. UTC

From: Girish K S <[e-mail]>

The existing driver supports gpio based /cs signal.
For controller's that have one device per controller,
the slave device's /cs signal might be internally controlled
by the chip select bit of slave select register. They are not
externally asserted/deasserted using gpio pin.

This patch adds support for controllers with dedicated /cs pin.
if "cs-gpio" property doesnt exist in a spi dts node, the controller
would treat the /cs pin as dedicated.

Signed-off-by: Girish K S <[e-mail]>
---
 drivers/spi/spi-s3c64xx.c |   32 ++++++++++++++++++++++++--------
 1 files changed, 24 insertions(+), 8 deletions(-)

Comments

Mark Brown April 23, 2013, 2:42 p.m. UTC | #1

On Mon, Apr 22, 2013 at 12:39:24PM +0530, Girish K S wrote:
> From: Girish K S <[e-mail]>
> 
> The existing driver supports gpio based /cs signal.
> For controller's that have one device per controller,
> the slave device's /cs signal might be internally controlled
> by the chip select bit of slave select register. They are not
> externally asserted/deasserted using gpio pin.

This doesn't build:

drivers/spi/spi-s3c64xx.c: In function 's3c64xx_get_slave_ctrldata':
drivers/spi/spi-s3c64xx.c:1023: error: 'sdd' undeclared (first use in this function)
drivers/spi/spi-s3c64xx.c:1023: error: (Each undeclared identifier is reported only once
drivers/spi/spi-s3c64xx.c:1023: error: for each function it appears in.)

[e-mail] April 24, 2013, 9:39 a.m. UTC | #2

On Tue, Apr 23, 2013 at 8:12 PM, Mark Brown <[e-mail]> wrote:
> On Mon, Apr 22, 2013 at 12:39:24PM +0530, Girish K S wrote:
>> From: Girish K S <[e-mail]>
>>
>> The existing driver supports gpio based /cs signal.
>> For controller's that have one device per controller,
>> the slave device's /cs signal might be internally controlled
>> by the chip select bit of slave select register. They are not
>> externally asserted/deasserted using gpio pin.
>
> This doesn't build:
>
> drivers/spi/spi-s3c64xx.c: In function 's3c64xx_get_slave_ctrldata':
> drivers/spi/spi-s3c64xx.c:1023: error: 'sdd' undeclared (first use in this function)
> drivers/spi/spi-s3c64xx.c:1023: error: (Each undeclared identifier is reported only once
> drivers/spi/spi-s3c64xx.c:1023: error: for each function it appears in.)

Ohhhhhh. Sorry. forgot to commit the changes before patch generation

Patch

diff --git a/drivers/spi/spi-s3c64xx.c b/drivers/spi/spi-s3c64xx.c
index 665fe2b..07f9e00 100644
--- a/drivers/spi/spi-s3c64xx.c
+++ b/drivers/spi/spi-s3c64xx.c
@@ -208,6 +208,7 @@  struct s3c64xx_spi_driver_data {
 	struct s3c64xx_spi_port_config	*port_conf;
 	unsigned int			port_id;
 	unsigned long			gpios[4];
+	bool				cs_gpio;
 };
 
 static void flush_fifo(struct s3c64xx_spi_driver_data *sdd)
@@ -570,14 +571,16 @@  static inline void enable_cs(struct s3c64xx_spi_driver_data *sdd,
 		if (sdd->tgl_spi != spi) { /* if last mssg on diff device */
 			/* Deselect the last toggled device */
 			cs = sdd->tgl_spi->controller_data;
-			gpio_set_value(cs->line,
-				spi->mode & SPI_CS_HIGH ? 0 : 1);
+			if (sdd->cs_gpio)
+				gpio_set_value(cs->line,
+					spi->mode & SPI_CS_HIGH ? 0 : 1);
 		}
 		sdd->tgl_spi = NULL;
 	}
 
 	cs = spi->controller_data;
-	gpio_set_value(cs->line, spi->mode & SPI_CS_HIGH ? 1 : 0);
+	if (sdd->cs_gpio)
+		gpio_set_value(cs->line, spi->mode & SPI_CS_HIGH ? 1 : 0);
 
 	/* Start the signals */
 	writel(0, sdd->regs + S3C64XX_SPI_SLAVE_SEL);
@@ -706,7 +709,8 @@  static inline void disable_cs(struct s3c64xx_spi_driver_data *sdd,
 	if (sdd->tgl_spi == spi)
 		sdd->tgl_spi = NULL;
 
-	gpio_set_value(cs->line, spi->mode & SPI_CS_HIGH ? 0 : 1);
+	if (sdd->cs_gpio)
+		gpio_set_value(cs->line, spi->mode & SPI_CS_HIGH ? 0 : 1);
 
 	/* Quiese the signals */
 	writel(S3C64XX_SPI_SLAVE_SIG_INACT, sdd->regs + S3C64XX_SPI_SLAVE_SEL);
@@ -1015,7 +1019,10 @@  static struct s3c64xx_spi_csinfo *s3c64xx_get_slave_ctrldata(
 		return ERR_PTR(-ENOMEM);
 	}
 
-	cs->line = of_get_named_gpio(data_np, "cs-gpio", 0);
+	/* The CS line is asserted/deasserted by the gpio pin */
+	if (sdd->cs_gpio)
+		cs->line = of_get_named_gpio(data_np, "cs-gpio", 0);
+
 	if (!gpio_is_valid(cs->line)) {
 		dev_err(&spi->dev, "chip select gpio is not specified or invalid\n");
 		kfree(cs);
@@ -1055,7 +1062,8 @@  static int s3c64xx_spi_setup(struct spi_device *spi)
 		return -ENODEV;
 	}
 
-	if (!spi_get_ctldata(spi)) {
+	/* Request gpio only if cs line is asserted by gpio pins */
+	if (sdd->cs_gpio) {
 		err = gpio_request_one(cs->line, GPIOF_OUT_INIT_HIGH,
 				       dev_name(&spi->dev));
 		if (err) {
@@ -1064,9 +1072,11 @@  static int s3c64xx_spi_setup(struct spi_device *spi)
 				cs->line, err);
 			goto err_gpio_req;
 		}
-		spi_set_ctldata(spi, cs);
 	}
 
+	if (!spi_get_ctldata(spi))
+		spi_set_ctldata(spi, cs);
+
 	sci = sdd->cntrlr_info;
 
 	spin_lock_irqsave(&sdd->lock, flags);
@@ -1144,8 +1154,10 @@  err_gpio_req:
 static void s3c64xx_spi_cleanup(struct spi_device *spi)
 {
 	struct s3c64xx_spi_csinfo *cs = spi_get_ctldata(spi);
+	struct s3c64xx_spi_driver_data *sdd;
 
-	if (cs) {
+	sdd = spi_master_get_devdata(spi->master);
+	if (cs && sdd->cs_gpio) {
 		gpio_free(cs->line);
 		if (spi->dev.of_node)
 			kfree(cs);
@@ -1322,7 +1334,11 @@  static int s3c64xx_spi_probe(struct platform_device *pdev)
 	sdd->cntrlr_info = sci;
 	sdd->pdev = pdev;
 	sdd->sfr_start = mem_res->start;
+	sdd->cs_gpio = false;
 	if (pdev->dev.of_node) {
+		if (of_find_property(pdev->dev.of_node, "cs-gpio", NULL))
+			sdd->cs_gpio = true;
+
 		ret = of_alias_get_id(pdev->dev.of_node, "spi");
 		if (ret < 0) {
 			dev_err(&pdev->dev, "failed to get alias id, errno %d\n",