[PATCH RFT] gpio: dw: make deep probe compatible

[Ahmad Fatoum]

When deep probing GPIO controller, we expect struct gpio_chip::dev to be
bound to a driver.

This is currently not the case as the driver for the parent nodes
creates devices for the child nodes and never binds a driver to them.

As the child nodes have compatibles themselves too, let's match against
proper drivers.

Reported-by: David Picard <david.pic...@clermont.in2p3.fr>
Signed-off-by: Ahmad Fatoum <a.fat...@pengutronix.de>
---
@David, can you test?
---
 drivers/gpio/gpio-dw.c | 44 ++++++++++++++++++++++++------------------
 1 file changed, 25 insertions(+), 19 deletions(-)

diff --git a/drivers/gpio/gpio-dw.c b/drivers/gpio/gpio-dw.c
index 98668c0a2d54..688b2536be2b 100644
--- a/drivers/gpio/gpio-dw.c
+++ b/drivers/gpio/gpio-dw.c
@@ -6,6 +6,7 @@
  */
 
 #include <common.h>
+#include <linux/device.h>
 #include <errno.h>
 #include <io.h>
 #include <gpio.h>
@@ -104,9 +105,9 @@ static struct gpio_ops dw_gpio_ops = {
        .set = dw_gpio_set,
 };
 
-static int dw_gpio_add_port(struct device *dev, struct device_node *node,
-                           struct dw_gpio *parent)
+static int dw_gpio_add_port(struct device *dev)
 {
+       struct dw_gpio *parent = dev_get_drvdata(dev->parent);
        struct dw_gpio_instance *chip;
        uint32_t config1, config2;
        int ngpio, ret;
@@ -130,17 +131,7 @@ static int dw_gpio_add_port(struct device *dev, struct 
device_node *node,
 
        chip->parent = parent;
        chip->chip.ngpio = ngpio;
-       chip->chip.dev = add_generic_device("dw-port", DEVICE_ID_DYNAMIC, NULL,
-                                           dev->resource[0].start,
-                                           resource_size(&dev->resource[0]),
-                                           IORESOURCE_MEM, NULL);
-
-       if (!chip->chip.dev) {
-               dev_err(dev, "unable to add device\n");
-               return -ENODEV;
-       }
-
-       chip->chip.dev->of_node = node;
+       chip->chip.dev = dev;
 
        ret = gpiochip_add(&chip->chip);
        if (ret)
@@ -152,11 +143,22 @@ static int dw_gpio_add_port(struct device *dev, struct 
device_node *node,
        return 0;
 }
 
+static struct of_device_id dwgpio_port_match[] = {
+       { .compatible = "snps,dw-apb-gpio-port" },
+       { /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, dwgpio_port_match);
+
+static struct driver dwgpio_port_driver = {
+       .name = "dw-apb-gpio-port",
+       .probe = dw_gpio_add_port,
+       .of_compatible = dwgpio_port_match,
+};
+
 static int dw_gpio_probe(struct device *dev)
 {
        struct resource *iores;
        struct dw_gpio *gpio;
-       struct device_node *node;
 
        gpio = xzalloc(sizeof(*gpio));
 
@@ -165,13 +167,12 @@ static int dw_gpio_probe(struct device *dev)
                return PTR_ERR(iores);
        gpio->regs = IOMEM(iores->start);
 
-       for_each_child_of_node(dev->of_node, node)
-               dw_gpio_add_port(dev, node, gpio);
+       dev_set_drvdata(dev, gpio);
 
-       return 0;
+       return of_platform_populate(dev->of_node, NULL, dev);
 }
 
-static __maybe_unused struct of_device_id dwgpio_match[] = {
+static struct of_device_id dwgpio_match[] = {
        {
                .compatible = "snps,dw-apb-gpio",
        }, {
@@ -186,4 +187,9 @@ static struct driver dwgpio_driver = {
        .of_compatible = dwgpio_match,
 };
 
-postcore_platform_driver(dwgpio_driver);
+static int __init dwgpio_driver_register(void)
+{
+       platform_driver_register(&dwgpio_port_driver);
+       return platform_driver_register(&dwgpio_driver);
+}
+postcore_initcall(dwgpio_driver_register);
-- 
2.39.5