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>

diff --git a/Documentation/devicetree/bindings/spi/spi-gpio.txt b/Documentation/devicetree/bindings/spi/spi-gpio.txt
new file mode 100644 (file)
index 0000000..8a824be
--- /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 ff7263ce12c7e6a791359f6d1ff8b643f41067bd..aed1615958408a0d31a664cb6a1757fda5a22709 100644 (file)
--- 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),
 };