pinctrl: exynos: bind GPIO driver along with pinctrl

The devicetree of Samsung devices typically have the pin controller and
GPIO bank descriptors under the same pinctrl node. In U-Boot, these are
handled by two separate drivers. It is not possible to invoke both
drivers from a single node compatible.

Bind the GPIO driver on pinctrl driver bind, with the same OF node as
the pinctrl driver. This solution is already being used in other pinctrl
drivers. The hierarchy, as represented in `dm tree`, is as follows:

  pinctrl@13750000
  |-- gpio-banks
  |   |-- gpr0-gpio-bank
  |   |-- gpr1-gpio-bank
  |   |-- gpr2-gpio-bank
  |   |-- gpr3-gpio-bank
  |   `-- gpr4-gpio-bank
  |-- sd0-bus-width1-pins
  |-- sd0-bus-width4-pins
  |-- sd0-bus-width8-pins
  `-- sd0-clk-pins

Since a bind function doesn't exist, create and add it to all pinctrl
drivers.

Signed-off-by: Kaustabh Chakraborty <kauschluss@disroot.org>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>

drivers/pinctrl/exynos/pinctrl-exynos.c

@@ -7,6 +7,7 @@
 
 #include <log.h>
 #include <dm.h>
+#include <dm/lists.h>
 #include <errno.h>
 #include <asm/io.h>
 #include "pinctrl-exynos.h"
@@ -178,3 +179,13 @@ int exynos_pinctrl_probe(struct udevice *dev)
 
 	return 0;
 }
+
+int exynos_pinctrl_bind(struct udevice *dev)
+{
+	/*
+	 * Attempt to bind the Exynos GPIO driver. The GPIOs and
+	 * pin controller descriptors are found in the same OF node.
+	 */
+	return device_bind_driver_to_node(dev, "gpio_exynos", "gpio-banks",
+					  dev_ofnode(dev), NULL);
+}

drivers/pinctrl/exynos/pinctrl-exynos.h

@@ -97,5 +97,6 @@ void exynos_pinctrl_setup_peri(struct exynos_pinctrl_config_data *conf,
 int exynos_pinctrl_set_state(struct udevice *dev,
 		struct udevice *config);
 int exynos_pinctrl_probe(struct udevice *dev);
+int exynos_pinctrl_bind(struct udevice *dev);
 
 #endif /* __PINCTRL_EXYNOS_H_ */

drivers/pinctrl/exynos/pinctrl-exynos7420.c

@@ -114,4 +114,5 @@ U_BOOT_DRIVER(pinctrl_exynos7420) = {
 	.priv_auto	= sizeof(struct exynos_pinctrl_priv),
 	.ops		= &exynos7420_pinctrl_ops,
 	.probe		= exynos_pinctrl_probe,
+	.bind		= exynos_pinctrl_bind,
 };

drivers/pinctrl/exynos/pinctrl-exynos78x0.c

@@ -115,4 +115,5 @@ U_BOOT_DRIVER(pinctrl_exynos78x0) = {
 	.priv_auto = sizeof(struct exynos_pinctrl_priv),
 	.ops		= &exynos78x0_pinctrl_ops,
 	.probe		= exynos_pinctrl_probe,
+	.bind		= exynos_pinctrl_bind,
 };

drivers/pinctrl/exynos/pinctrl-exynos850.c

@@ -122,4 +122,5 @@ U_BOOT_DRIVER(pinctrl_exynos850) = {
 	.priv_auto	= sizeof(struct exynos_pinctrl_priv),
 	.ops		= &exynos850_pinctrl_ops,
 	.probe		= exynos_pinctrl_probe,
+	.bind		= exynos_pinctrl_bind,
 };