[PATCH v3 4/5] pinctrl: renesas: gpio: support software nodes for function GPIOs

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

This patch extends the sh-pfc GPIO driver to support software-node-based
configuration for the secondary 'function' GPIO chip.

While the primary GPIO chip typically uses the firmware node attached to
the parent platform device, the secondary chip should target a specific
child node to avoid ambiguity when defining GPIO hogs or properties.

Update gpio_function_setup() to look for a child node named 'functions',
but only when the parent is a software node. This ensures the behavior
is restricted to legacy platforms being migrated to software nodes.

Assisted-by: LLM
Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
Reviewed-by: Linus Walleij <linusw@kernel.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
---
 drivers/pinctrl/renesas/gpio.c | 28 +++++++++++++++++++++++++---
 1 file changed, 25 insertions(+), 3 deletions(-)

diff --git a/drivers/pinctrl/renesas/gpio.c b/drivers/pinctrl/renesas/gpio.c
index 4e59dadb7364..b49a3e14da91 100644
--- a/drivers/pinctrl/renesas/gpio.c
+++ b/drivers/pinctrl/renesas/gpio.c
@@ -271,18 +271,40 @@ static int gpio_function_request(struct gpio_chip *gc, unsigned offset)
 	return ret;
 }
 
+static void sh_pfc_fwnode_put(void *data)
+{
+	fwnode_handle_put(data);
+}
+
 static int gpio_function_setup(struct sh_pfc_chip *chip)
 {
 	struct sh_pfc *pfc = chip->pfc;
 	struct gpio_chip *gc = &chip->gpio_chip;
+	struct fwnode_handle *fwnode = dev_fwnode(pfc->dev);
 
 	gc->request = gpio_function_request;
 
+	if (is_software_node(fwnode)) {
+		fwnode = fwnode_get_named_child_node(fwnode, "functions");
+		if (fwnode) {
+			int ret;
+
+			ret = devm_add_action_or_reset(pfc->dev,
+						       sh_pfc_fwnode_put,
+						       fwnode);
+			if (ret)
+				return ret;
+
+			gc->fwnode = fwnode;
+		}
+	}
+
 	/*
-	 * Explicitly mask the parent's fwnode to prevent gpiolib from
-	 * reusing it for function GPIOs.
+	 * If we did not find 'functions' node, explicitly mask the parent's
+	 * fwnode to prevent gpiolib from reusing it for function GPIOs.
 	 */
-	gc->fwnode = ERR_PTR(-ENODEV);
+	if (!gc->fwnode)
+		gc->fwnode = ERR_PTR(-ENODEV);
 
 	gc->label = pfc->info->name;
 	gc->owner = THIS_MODULE;

-- 
2.56.0.rc1.315.gc6ed9934b7-goog