Message-ID: <20251002215759.1836706-1-markus.probst@posteo.de>
Date: Thu, 02 Oct 2025 21:58:05 +0000
From: Markus Probst <markus.probst@...teo.de>
To: Linus Walleij <linus.walleij@...aro.org>,
	Bartosz Golaszewski <brgl@...ev.pl>,
	Mika Westerberg <westeri@...nel.org>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc: linux-gpio@...r.kernel.org,
	linux-acpi@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Markus Probst <markus.probst@...teo.de>
Subject: [PATCH] gpio: of: make it possible to reference gpios probed in acpi in device tree

sometimes it is necessary to use both acpi and device tree to declare
devices. Not every gpio device driver which has an acpi_match_table has
an of_match table (e.g. amd-pinctrl). Furthermore gpio is an device which
can't be easily disabled in acpi and then redeclared in device tree, as
it often gets used by other devices declared in acpi (e.g. via GpioInt or
GpioIo). Thus a disable of acpi and migration to device tree is not always
possible or very time consuming, while acpi by itself is very limited and
not always sufficient. This won't affect most configurations, as most of
the time either CONFIG_ACPI or CONFIG_OF gets enabled, not both.

Signed-off-by: Markus Probst <markus.probst@...teo.de>
---
 drivers/gpio/gpiolib-of.c | 241 +++++++++++++++++++++++---------------
 1 file changed, 145 insertions(+), 96 deletions(-)

diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c
index 37ab78243fab..c472b86148b3 100644
--- a/drivers/gpio/gpiolib-of.c
+++ b/drivers/gpio/gpiolib-of.c
@@ -18,6 +18,7 @@
 #include <linux/pinctrl/pinctrl.h>
 #include <linux/slab.h>
 #include <linux/string.h>
+#include <linux/acpi.h>
 
 #include <linux/gpio/consumer.h>
 #include <linux/gpio/machine.h>
@@ -118,6 +119,107 @@ int of_gpio_count(const struct fwnode_handle *fwnode, const char *con_id)
 	return ret ? ret : -ENOENT;
 }
 
+/**
+ * of_gpio_twocell_xlate - translate twocell gpiospec to the GPIO number and flags
+ * @gc:		pointer to the gpio_chip structure
+ * @gpiospec:	GPIO specifier as found in the device tree
+ * @flags:	a flags pointer to fill in
+ *
+ * This is simple translation function, suitable for the most 1:1 mapped
+ * GPIO chips. This function performs only one sanity check: whether GPIO
+ * is less than ngpios (that is specified in the gpio_chip).
+ *
+ * Returns:
+ * GPIO number (>= 0) on success, negative errno on failure.
+ */
+static int of_gpio_twocell_xlate(struct gpio_chip *gc,
+				 const struct of_phandle_args *gpiospec,
+				 u32 *flags)
+{
+	/*
+	 * We're discouraging gpio_cells < 2, since that way you'll have to
+	 * write your own xlate function (that will have to retrieve the GPIO
+	 * number and the flags from a single gpio cell -- this is possible,
+	 * but not recommended).
+	 */
+	if (gc->of_gpio_n_cells != 2) {
+		WARN_ON(1);
+		return -EINVAL;
+	}
+
+	if (WARN_ON(gpiospec->args_count < gc->of_gpio_n_cells))
+		return -EINVAL;
+
+	if (gpiospec->args[0] >= gc->ngpio)
+		return -EINVAL;
+
+	if (flags)
+		*flags = gpiospec->args[1];
+
+	return gpiospec->args[0];
+}
+
+/**
+ * of_gpio_threecell_xlate - translate threecell gpiospec to the GPIO number and flags
+ * @gc:		pointer to the gpio_chip structure
+ * @gpiospec:	GPIO specifier as found in the device tree
+ * @flags:	a flags pointer to fill in
+ *
+ * This is simple translation function, suitable for the most 1:n mapped
+ * GPIO chips, i.e. several GPIO chip instances from one device tree node.
+ * In this case the following binding is implied:
+ *
+ * foo-gpios = <&gpio instance offset flags>;
+ *
+ * Returns:
+ * GPIO number (>= 0) on success, negative errno on failure.
+ */
+static int of_gpio_threecell_xlate(struct gpio_chip *gc,
+				   const struct of_phandle_args *gpiospec,
+				   u32 *flags)
+{
+	if (gc->of_gpio_n_cells != 3) {
+		WARN_ON(1);
+		return -EINVAL;
+	}
+
+	if (WARN_ON(gpiospec->args_count != 3))
+		return -EINVAL;
+
+	/*
+	 * Check chip instance number, the driver responds with true if
+	 * this is the chip we are looking for.
+	 */
+	if (!gc->of_node_instance_match(gc, gpiospec->args[0]))
+		return -EINVAL;
+
+	if (gpiospec->args[1] >= gc->ngpio)
+		return -EINVAL;
+
+	if (flags)
+		*flags = gpiospec->args[2];
+
+	return gpiospec->args[1];
+}
+
+static int of_gpiochip_init(struct gpio_chip *chip)
+{
+	if (!chip->of_xlate) {
+		if (chip->of_gpio_n_cells == 3) {
+			if (!chip->of_node_instance_match)
+				return -EINVAL;
+			chip->of_xlate = of_gpio_threecell_xlate;
+		} else {
+			chip->of_gpio_n_cells = 2;
+			chip->of_xlate = of_gpio_twocell_xlate;
+		}
+	}
+
+	if (chip->of_gpio_n_cells > MAX_PHANDLE_ARGS)
+		return -EINVAL;
+	return 0;
+}
+
 static int of_gpiochip_match_node_and_xlate(struct gpio_chip *chip,
 					    const void *data)
 {
@@ -134,6 +236,40 @@ of_find_gpio_device_by_xlate(const struct of_phandle_args *gpiospec)
 	return gpio_device_find(gpiospec, of_gpiochip_match_node_and_xlate);
 }
 
+#ifdef CONFIG_ACPI
+static int of_gpiochip_match_acpi_path(struct gpio_chip *chip,
+				       const void *data)
+{
+	const char *acpi_path = data;
+	const char *chip_acpi_path;
+	acpi_handle handle;
+	int ret;
+
+	handle = ACPI_HANDLE(chip->parent);
+	if (!handle)
+		return 0;
+	chip_acpi_path = acpi_handle_path(handle);
+	if (!chip_acpi_path)
+		return 0;
+
+	ret = !strcmp(acpi_path, chip_acpi_path);
+
+	if (ret)
+		ret = !of_gpiochip_init(chip);
+
+	return ret;
+}
+
+static struct gpio_device *of_find_gpio_device_by_acpi(const struct of_phandle_args *gpiospec)
+{
+	const char *acpi_path = NULL;
+
+	if (of_property_read_string(gpiospec->np, "acpi-path", &acpi_path))
+		return NULL;
+	return gpio_device_find(acpi_path, of_gpiochip_match_acpi_path);
+}
+#endif
+
 static struct gpio_desc *of_xlate_and_get_gpiod_flags(struct gpio_chip *chip,
 					struct of_phandle_args *gpiospec,
 					enum of_gpio_flags *flags)
@@ -423,6 +559,12 @@ static struct gpio_desc *of_get_named_gpiod_flags(const struct device_node *np,
 
 	struct gpio_device *gdev __free(gpio_device_put) =
 				of_find_gpio_device_by_xlate(&gpiospec);
+	#ifdef CONFIG_ACPI
+	if (!gdev) {
+		gdev = of_find_gpio_device_by_acpi(&gpiospec);
+	}
+	#endif
+
 	if (!gdev) {
 		desc = ERR_PTR(-EPROBE_DEFER);
 		goto out;
@@ -948,89 +1090,6 @@ struct notifier_block gpio_of_notifier = {
 };
 #endif /* CONFIG_OF_DYNAMIC */
 
-/**
- * of_gpio_twocell_xlate - translate twocell gpiospec to the GPIO number and flags
- * @gc:		pointer to the gpio_chip structure
- * @gpiospec:	GPIO specifier as found in the device tree
- * @flags:	a flags pointer to fill in
- *
- * This is simple translation function, suitable for the most 1:1 mapped
- * GPIO chips. This function performs only one sanity check: whether GPIO
- * is less than ngpios (that is specified in the gpio_chip).
- *
- * Returns:
- * GPIO number (>= 0) on success, negative errno on failure.
- */
-static int of_gpio_twocell_xlate(struct gpio_chip *gc,
-				 const struct of_phandle_args *gpiospec,
-				 u32 *flags)
-{
-	/*
-	 * We're discouraging gpio_cells < 2, since that way you'll have to
-	 * write your own xlate function (that will have to retrieve the GPIO
-	 * number and the flags from a single gpio cell -- this is possible,
-	 * but not recommended).
-	 */
-	if (gc->of_gpio_n_cells != 2) {
-		WARN_ON(1);
-		return -EINVAL;
-	}
-
-	if (WARN_ON(gpiospec->args_count < gc->of_gpio_n_cells))
-		return -EINVAL;
-
-	if (gpiospec->args[0] >= gc->ngpio)
-		return -EINVAL;
-
-	if (flags)
-		*flags = gpiospec->args[1];
-
-	return gpiospec->args[0];
-}
-
-/**
- * of_gpio_threecell_xlate - translate threecell gpiospec to the GPIO number and flags
- * @gc:		pointer to the gpio_chip structure
- * @gpiospec:	GPIO specifier as found in the device tree
- * @flags:	a flags pointer to fill in
- *
- * This is simple translation function, suitable for the most 1:n mapped
- * GPIO chips, i.e. several GPIO chip instances from one device tree node.
- * In this case the following binding is implied:
- *
- * foo-gpios = <&gpio instance offset flags>;
- *
- * Returns:
- * GPIO number (>= 0) on success, negative errno on failure.
- */
-static int of_gpio_threecell_xlate(struct gpio_chip *gc,
-				   const struct of_phandle_args *gpiospec,
-				   u32 *flags)
-{
-	if (gc->of_gpio_n_cells != 3) {
-		WARN_ON(1);
-		return -EINVAL;
-	}
-
-	if (WARN_ON(gpiospec->args_count != 3))
-		return -EINVAL;
-
-	/*
-	 * Check chip instance number, the driver responds with true if
-	 * this is the chip we are looking for.
-	 */
-	if (!gc->of_node_instance_match(gc, gpiospec->args[0]))
-		return -EINVAL;
-
-	if (gpiospec->args[1] >= gc->ngpio)
-		return -EINVAL;
-
-	if (flags)
-		*flags = gpiospec->args[2];
-
-	return gpiospec->args[1];
-}
-
 #if IS_ENABLED(CONFIG_OF_GPIO_MM_GPIOCHIP)
 #include <linux/gpio/legacy-of-mm-gpiochip.h>
 /**
@@ -1256,19 +1315,9 @@ int of_gpiochip_add(struct gpio_chip *chip)
 	if (!np)
 		return 0;
 
-	if (!chip->of_xlate) {
-		if (chip->of_gpio_n_cells == 3) {
-			if (!chip->of_node_instance_match)
-				return -EINVAL;
-			chip->of_xlate = of_gpio_threecell_xlate;
-		} else {
-			chip->of_gpio_n_cells = 2;
-			chip->of_xlate = of_gpio_twocell_xlate;
-		}
-	}
-
-	if (chip->of_gpio_n_cells > MAX_PHANDLE_ARGS)
-		return -EINVAL;
+	ret = of_gpiochip_init(chip);
+	if (ret)
+		return ret;
 
 	ret = of_gpiochip_add_pin_range(chip);
 	if (ret)
-- 
2.49.1

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