spi: spi-gpio: Add DT bindings

This patch adds DT bindings to the spi-gpio driver and some
documentation about how to use it.

Signed-off-by: Daniel Mack <zonque@gmail.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

2 files changed, 125 insertions, 3 deletions

diff --git a/Documentation/devicetree/bindings/spi/spi-gpio.txt b/Documentation/devicetree/bindings/spi/spi-gpio.txt
new file mode 100644
index 000000000000..8a824be15754
--- /dev/null
+++ b/Documentation/devicetree/bindings/spi/spi-gpio.txt
@@ -0,0 +1,29 @@
+SPI-GPIO devicetree bindings
+
+Required properties:
+
+ - compatible: should be set to "spi-gpio"
+ - #address-cells: should be set to <0x1>
+ - ranges
+ - gpio-sck: GPIO spec for the SCK line to use
+ - gpio-miso: GPIO spec for the MISO line to use
+ - gpio-mosi: GPIO spec for the MOSI line to use
+ - cs-gpios: GPIOs to use for chipselect lines
+ - num-chipselects: number of chipselect lines
+
+Example:
+
+        spi {
+                compatible = "spi-gpio";
+                #address-cells = <0x1>;
+                ranges;
+
+                gpio-sck = <&gpio 95 0>;
+                gpio-miso = <&gpio 98 0>;
+                gpio-mosi = <&gpio 97 0>;
+                cs-gpios = <&gpio 125 0>;
+                num-chipselects = <1>;
+
+                /* clients */
+        };
+
diff --git a/drivers/spi/spi-gpio.c b/drivers/spi/spi-gpio.c
index ff7263ce12c7..aed161595840 100644
--- a/drivers/spi/spi-gpio.c
+++ b/drivers/spi/spi-gpio.c
@@ -22,6 +22,8 @@
 #include <linux/init.h>
 #include <linux/platform_device.h>
 #include <linux/gpio.h>
+#include <linux/of_device.h>
+#include <linux/of_gpio.h>
 
 #include <linux/spi/spi.h>
 #include <linux/spi/spi_bitbang.h>
@@ -232,13 +234,27 @@ static void spi_gpio_chipselect(struct spi_device *spi, int is_active)
 
 static int spi_gpio_setup(struct spi_device *spi)
 {
-        unsigned int            cs = (unsigned int) spi->controller_data;
+        unsigned int            cs;
         int                     status = 0;
         struct spi_gpio         *spi_gpio = spi_to_spi_gpio(spi);
+        struct device_node      *np = spi->master->dev.of_node;
 
         if (spi->bits_per_word > 32)
                 return -EINVAL;
 
+        if (np) {
+                /*
+                 * In DT environments, the CS GPIOs have already been
+                 * initialized from the "cs-gpios" property of the node.
+                 */
+                cs = spi_gpio->cs_gpios[spi->chip_select];
+        } else {
+                /*
+                 * ... otherwise, take it from spi->controller_data
+                 */
+                cs = (unsigned int) spi->controller_data;
+        }
+
         if (!spi->controller_state) {
                 if (cs != SPI_GPIO_NO_CHIPSELECT) {
                         status = gpio_request(cs, dev_name(&spi->dev));
@@ -250,6 +266,7 @@ static int spi_gpio_setup(struct spi_device *spi)
         }
         if (!status) {
                 status = spi_bitbang_setup(spi);
+                /* in case it was initialized from static board data */
                 spi_gpio->cs_gpios[spi->chip_select] = cs;
         }
 
@@ -326,6 +343,55 @@ done:
         return value;
 }
 
+#ifdef CONFIG_OF
+static struct of_device_id spi_gpio_dt_ids[] = {
+        { .compatible = "spi-gpio" },
+        {}
+};
+MODULE_DEVICE_TABLE(of, spi_gpio_dt_ids);
+
+static int spi_gpio_probe_dt(struct platform_device *pdev)
+{
+        int ret;
+        u32 tmp;
+        struct spi_gpio_platform_data   *pdata;
+        struct device_node *np = pdev->dev.of_node;
+        const struct of_device_id *of_id =
+                        of_match_device(spi_gpio_dt_ids, &pdev->dev);
+
+        if (!of_id)
+                return 0;
+
+        pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
+        if (!pdata)
+                return -ENOMEM;
+
+        pdata->sck = of_get_named_gpio(np, "gpio-sck", 0);
+        pdata->miso = of_get_named_gpio(np, "gpio-miso", 0);
+        pdata->mosi = of_get_named_gpio(np, "gpio-mosi", 0);
+
+        ret = of_property_read_u32(np, "num-chipselects", &tmp);
+        if (ret < 0) {
+                dev_err(&pdev->dev, "num-chipselects property not found\n");
+                goto error_free;
+        }
+
+        pdata->num_chipselect = tmp;
+        pdev->dev.platform_data = pdata;
+
+        return 1;
+
+error_free:
+        devm_kfree(&pdev->dev, pdata);
+        return ret;
+}
+#else
+static inline int spi_probe_dt(struct platform_device *)
+{
+        return 0;
+}
+#endif
+
 static int __devinit spi_gpio_probe(struct platform_device *pdev)
 {
         int                             status;
@@ -333,6 +399,13 @@ static int __devinit spi_gpio_probe(struct platform_device *pdev)
         struct spi_gpio                 *spi_gpio;
         struct spi_gpio_platform_data   *pdata;
         u16 master_flags = 0;
+        bool use_of = 0;
+
+        status = spi_gpio_probe_dt(pdev);
+        if (status < 0)
+                return status;
+        if (status > 0)
+                use_of = 1;
 
         pdata = pdev->dev.platform_data;
 #ifdef GENERIC_BITBANG
@@ -362,6 +435,23 @@ static int __devinit spi_gpio_probe(struct platform_device *pdev)
         master->num_chipselect = SPI_N_CHIPSEL;
         master->setup = spi_gpio_setup;
         master->cleanup = spi_gpio_cleanup;
+#ifdef CONFIG_OF
+        master->dev.of_node = pdev->dev.of_node;
+
+        if (use_of) {
+                int i;
+                struct device_node *np = pdev->dev.of_node;
+
+                /*
+                 * In DT environments, take the CS GPIO from the "cs-gpios"
+                 * property of the node.
+                 */
+
+                for (i = 0; i < SPI_N_CHIPSEL; i++)
+                        spi_gpio->cs_gpios[i] =
+                                of_get_named_gpio(np, "cs-gpios", i);
+        }
+#endif
 
         spi_gpio->bitbang.master = spi_master_get(master);
         spi_gpio->bitbang.chipselect = spi_gpio_chipselect;
@@ -422,8 +512,11 @@ static int __devexit spi_gpio_remove(struct platform_device *pdev)
 MODULE_ALIAS("platform:" DRIVER_NAME);
 
 static struct platform_driver spi_gpio_driver = {
-        .driver.name    = DRIVER_NAME,
-        .driver.owner   = THIS_MODULE,
+        .driver = {
+                .name   = DRIVER_NAME,
+                .owner  = THIS_MODULE,
+                .of_match_table = of_match_ptr(spi_gpio_dt_ids),
+        },
         .probe          = spi_gpio_probe,
         .remove         = __devexit_p(spi_gpio_remove),
 };