spi: s3c64xx: Added provision for dedicated cs pin

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 <ks.giri@samsung.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

diff --git a/drivers/spi/spi-s3c64xx.c b/drivers/spi/spi-s3c64xx.c
index 70b2213..067f442 100644 (file)
--- 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);
@@ -710,7 +713,8 @@ 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);
@@ -998,8 +1002,10 @@ static struct s3c64xx_spi_csinfo *s3c64xx_get_slave_ctrldata(
 {
        struct s3c64xx_spi_csinfo *cs;
        struct device_node *slave_np, *data_np = NULL;
+       struct s3c64xx_spi_driver_data *sdd;
        u32 fb_delay = 0;
 
+       sdd = spi_master_get_devdata(spi->master);
        slave_np = spi->dev.of_node;
        if (!slave_np) {
                dev_err(&spi->dev, "device node not found\n");
@@ -1019,7 +1025,10 @@ 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);
@@ -1059,7 +1068,8 @@ 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) {
@@ -1068,9 +1078,11 @@ 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);
@@ -1148,8 +1160,10 @@ 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);
@@ -1326,7 +1340,11 @@ 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 = true;
        if (pdev->dev.of_node) {
+               if (!of_find_property(pdev->dev.of_node, "cs-gpio", NULL))
+                       sdd->cs_gpio = false;
+
                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",