drivers: gpio: add mp2 gpio clock handling

Remove gpio clock management from the GPIO driver when running on the
cortex-m33 on the mp2 and gpio clocks are managed by the cortex-A, being
the resource manager, allowed by the Resource Isolation Framework (RIF).
Also add a specific binding for the mp2 gpio to make clock property
optional.

Signed-off-by: Youssef Zini <youssef.zini@savoirfairelinux.com>

drivers/gpio/Kconfig.stm32

@@ -1,11 +1,12 @@
 # STM32 GPIO configuration
 
 # Copyright (c) 2016 Open-RnD Sp. z o.o.
+# Copyright (C) 2025 Savoir-faire Linux, Inc.
 # SPDX-License-Identifier: Apache-2.0
 
 config GPIO_STM32
 	bool "GPIO Driver for STM32 family of MCUs"
 	default y
-	depends on DT_HAS_ST_STM32_GPIO_ENABLED
+	depends on DT_HAS_ST_STM32_GPIO_ENABLED || DT_HAS_ST_STM32MP2_GPIO_ENABLED
 	help
 	  Enable GPIO driver for STM32 line of MCUs

drivers/gpio/gpio_stm32.c

@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2016 Open-RnD Sp. z o.o.
+ * Copyright (C) 2025 Savoir-faire Linux, Inc.
  *
  * SPDX-License-Identifier: Apache-2.0
  */
@@ -708,7 +709,7 @@ static int gpio_stm32_pm_action(const struct device *dev,
  *
  * @return 0
  */
-static int gpio_stm32_init(const struct device *dev)
+__maybe_unused static int gpio_stm32_init(const struct device *dev)
 {
 	struct gpio_stm32_data *data = dev->data;
 
@@ -741,12 +742,16 @@ static int gpio_stm32_init(const struct device *dev)
 		},							       \
 		.base = (uint32_t *)__base_addr,				       \
 		.port = __port,						       \
-		.pclken = { .bus = __bus, .enr = __cenr }		       \
+		COND_CODE_1(DT_NODE_HAS_PROP(__node, clocks),		       \
+			   (.pclken = { .bus = __bus, .enr = __cenr },),       \
+			   (/* Nothing if clocks not present */))	       \
 	};								       \
 	static struct gpio_stm32_data gpio_stm32_data_## __suffix;	       \
 	PM_DEVICE_DT_DEFINE(__node, gpio_stm32_pm_action);		       \
 	DEVICE_DT_DEFINE(__node,					       \
-			    gpio_stm32_init,				       \
+			    COND_CODE_1(DT_NODE_HAS_PROP(__node, clocks),      \
+					(gpio_stm32_init),		       \
+					(NULL)),			       \
 			    PM_DEVICE_DT_GET(__node),			       \
 			    &gpio_stm32_data_## __suffix,		       \
 			    &gpio_stm32_cfg_## __suffix,		       \

dts/bindings/gpio/st,stm32mp2-gpio.yaml

@@ -0,0 +1,23 @@
+# Copyright (C) 2025 Savoir-faire Linux, Inc.
+# SPDX-License-Identifier: Apache-2.0
+
+description: STM32MP2 GPIO Controller
+
+compatible: "st,stm32mp2-gpio"
+
+include:
+  - name: st,stm32-gpio.yaml
+    property-blocklist:
+      - clocks
+
+properties:
+  clocks:
+    type: phandle-array
+    description: |
+      The clocks property is optional for STM32MP2 GPIO controllers.
+      This property is not required when the Cortex-A core is responsible for
+      GPIO initialization and acts as the resource manager, as defined by the
+      RIF (Resource Isolation Framework) peripheral. Adding the GPIO clocks
+      in that case would only trigger an IAC event.
+      If the Cortex-M core is designated as the resource manager, then the
+      clocks property must be defined and added to the device tree.