gpio: move hogs into GPIO core

Refactor line hogging code by moving the parts duplicated in
gpiolib-acpi-core.c and gpiolib-of.c into gpiolib.c, leaving just the
OF-specific bits in the latter.

This makes fwnode the primary API for setting up hogs and allows to use
software nodes in addition to ACPI and OF nodes.

Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Linus Walleij <linusw@kernel.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://patch.msgid.link/20260309-gpio-hog-fwnode-v2-2-4e61f3dbf06a@oss.qualcomm.com
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>

Author: Bartosz Golaszewski

drivers/gpio/gpiolib-acpi-core.c

@@ -1220,75 +1220,6 @@ static void acpi_gpiochip_free_regions(struct acpi_gpio_chip *achip)
 	}
 }
 
-static struct gpio_desc *
-acpi_gpiochip_parse_own_gpio(struct acpi_gpio_chip *achip,
-			     struct fwnode_handle *fwnode,
-			     const char **name,
-			     unsigned long *lflags,
-			     enum gpiod_flags *dflags)
-{
-	struct gpio_chip *chip = achip->chip;
-	struct gpio_desc *desc;
-	u32 gpios[2];
-	int ret;
-
-	*lflags = GPIO_LOOKUP_FLAGS_DEFAULT;
-	*dflags = GPIOD_ASIS;
-	*name = NULL;
-
-	ret = fwnode_property_read_u32_array(fwnode, "gpios", gpios,
-					     ARRAY_SIZE(gpios));
-	if (ret < 0)
-		return ERR_PTR(ret);
-
-	desc = gpiochip_get_desc(chip, gpios[0]);
-	if (IS_ERR(desc))
-		return desc;
-
-	if (gpios[1])
-		*lflags |= GPIO_ACTIVE_LOW;
-
-	if (fwnode_property_present(fwnode, "input"))
-		*dflags |= GPIOD_IN;
-	else if (fwnode_property_present(fwnode, "output-low"))
-		*dflags |= GPIOD_OUT_LOW;
-	else if (fwnode_property_present(fwnode, "output-high"))
-		*dflags |= GPIOD_OUT_HIGH;
-	else
-		return ERR_PTR(-EINVAL);
-
-	fwnode_property_read_string(fwnode, "line-name", name);
-
-	return desc;
-}
-
-static void acpi_gpiochip_scan_gpios(struct acpi_gpio_chip *achip)
-{
-	struct gpio_chip *chip = achip->chip;
-
-	device_for_each_child_node_scoped(chip->parent, fwnode) {
-		unsigned long lflags;
-		enum gpiod_flags dflags;
-		struct gpio_desc *desc;
-		const char *name;
-		int ret;
-
-		if (!fwnode_property_present(fwnode, "gpio-hog"))
-			continue;
-
-		desc = acpi_gpiochip_parse_own_gpio(achip, fwnode, &name,
-						    &lflags, &dflags);
-		if (IS_ERR(desc))
-			continue;
-
-		ret = gpiod_hog(desc, name, lflags, dflags);
-		if (ret) {
-			dev_err(chip->parent, "Failed to hog GPIO\n");
-			return;
-		}
-	}
-}
-
 void acpi_gpiochip_add(struct gpio_chip *chip)
 {
 	struct acpi_gpio_chip *acpi_gpio;
@@ -1321,7 +1252,6 @@ void acpi_gpiochip_add(struct gpio_chip *chip)
 	}
 
 	acpi_gpiochip_request_regions(acpi_gpio);
-	acpi_gpiochip_scan_gpios(acpi_gpio);
 	acpi_dev_clear_dependencies(adev);
 }
 

drivers/gpio/gpiolib-of.c

@@ -10,6 +10,7 @@
 #include <linux/device.h>
 #include <linux/err.h>
 #include <linux/errno.h>
+#include <linux/fwnode.h>
 #include <linux/io.h>
 #include <linux/module.h>
 #include <linux/of.h>
@@ -712,139 +713,26 @@ struct gpio_desc *of_find_gpio(struct device_node *np, const char *con_id,
 	return desc;
 }
 
-/**
- * of_parse_own_gpio() - Get a GPIO hog descriptor, names and flags for GPIO API
- * @np:		device node to get GPIO from
- * @chip:	GPIO chip whose hog is parsed
- * @idx:	Index of the GPIO to parse
- * @name:	GPIO line name
- * @lflags:	bitmask of gpio_lookup_flags GPIO_* values - returned from
- *		of_find_gpio() or of_parse_own_gpio()
- * @dflags:	gpiod_flags - optional GPIO initialization flags
- *
- * Returns:
- * GPIO descriptor to use with Linux GPIO API, or one of the errno
- * value on the error condition.
- */
-static struct gpio_desc *of_parse_own_gpio(struct device_node *np,
-					   struct gpio_chip *chip,
-					   unsigned int idx, const char **name,
-					   unsigned long *lflags,
-					   enum gpiod_flags *dflags)
+int of_gpiochip_get_lflags(struct gpio_chip *chip,
+			   struct fwnode_reference_args *gpiospec,
+			   unsigned long *lflags)
 {
-	struct device_node *chip_np;
 	enum of_gpio_flags xlate_flags;
-	struct of_phandle_args gpiospec;
+	struct of_phandle_args args;
 	struct gpio_desc *desc;
-	unsigned int i;
-	u32 tmp;
-	int ret;
-
-	chip_np = dev_of_node(&chip->gpiodev->dev);
-	if (!chip_np)
-		return ERR_PTR(-EINVAL);
-
-	xlate_flags = 0;
-	*lflags = GPIO_LOOKUP_FLAGS_DEFAULT;
-	*dflags = GPIOD_ASIS;
 
-	ret = of_property_read_u32(chip_np, "#gpio-cells", &tmp);
-	if (ret)
-		return ERR_PTR(ret);
+	args.np = to_of_node(gpiospec->fwnode);
+	args.args_count = gpiospec->nargs;
 
-	gpiospec.np = chip_np;
-	gpiospec.args_count = tmp;
-
-	for (i = 0; i < tmp; i++) {
-		ret = of_property_read_u32_index(np, "gpios", idx * tmp + i,
-						 &gpiospec.args[i]);
-		if (ret)
-			return ERR_PTR(ret);
-	}
+	for (int i = 0; i < args.args_count; i++)
+		args.args[i] = gpiospec->args[i];
 
-	desc = of_xlate_and_get_gpiod_flags(chip, &gpiospec, &xlate_flags);
+	desc = of_xlate_and_get_gpiod_flags(chip, &args, &xlate_flags);
 	if (IS_ERR(desc))
-		return desc;
+		return PTR_ERR(desc);
 
 	*lflags = of_convert_gpio_flags(xlate_flags);
 
-	if (of_property_read_bool(np, "input"))
-		*dflags |= GPIOD_IN;
-	else if (of_property_read_bool(np, "output-low"))
-		*dflags |= GPIOD_OUT_LOW;
-	else if (of_property_read_bool(np, "output-high"))
-		*dflags |= GPIOD_OUT_HIGH;
-	else {
-		pr_warn("GPIO line %d (%pOFn): no hogging state specified, bailing out\n",
-			desc_to_gpio(desc), np);
-		return ERR_PTR(-EINVAL);
-	}
-
-	if (name && of_property_read_string(np, "line-name", name))
-		*name = np->name;
-
-	return desc;
-}
-
-/**
- * of_gpiochip_add_hog - Add all hogs in a hog device node
- * @chip:	gpio chip to act on
- * @hog:	device node describing the hogs
- *
- * Returns:
- * 0 on success, or negative errno on failure.
- */
-static int of_gpiochip_add_hog(struct gpio_chip *chip, struct device_node *hog)
-{
-	enum gpiod_flags dflags;
-	struct gpio_desc *desc;
-	unsigned long lflags;
-	const char *name;
-	unsigned int i;
-	int ret;
-
-	for (i = 0;; i++) {
-		desc = of_parse_own_gpio(hog, chip, i, &name, &lflags, &dflags);
-		if (IS_ERR(desc))
-			break;
-
-		ret = gpiod_hog(desc, name, lflags, dflags);
-		if (ret < 0)
-			return ret;
-
-#ifdef CONFIG_OF_DYNAMIC
-		WRITE_ONCE(desc->hog, hog);
-#endif
-	}
-
-	return 0;
-}
-
-/**
- * of_gpiochip_scan_gpios - Scan gpio-controller for gpio definitions
- * @chip:	gpio chip to act on
- *
- * This is only used by of_gpiochip_add to request/set GPIO initial
- * configuration.
- *
- * Returns:
- * 0 on success, or negative errno on failure.
- */
-static int of_gpiochip_scan_gpios(struct gpio_chip *chip)
-{
-	int ret;
-
-	for_each_available_child_of_node_scoped(dev_of_node(&chip->gpiodev->dev), np) {
-		if (!of_property_read_bool(np, "gpio-hog"))
-			continue;
-
-		ret = of_gpiochip_add_hog(chip, np);
-		if (ret < 0)
-			return ret;
-
-		of_node_set_flag(np, OF_POPULATED);
-	}
-
 	return 0;
 }
 
@@ -899,7 +787,7 @@ static int of_gpio_notify(struct notifier_block *nb, unsigned long action,
 		if (!gdev)
 			return NOTIFY_DONE;	/* not for us */
 
-		ret = of_gpiochip_add_hog(gpio_device_get_chip(gdev), rd->dn);
+		ret = gpiochip_add_hog(gpio_device_get_chip(gdev), of_fwnode_handle(rd->dn));
 		if (ret < 0) {
 			pr_err("%s: failed to add hogs for %pOF\n", __func__,
 			       rd->dn);
@@ -1178,9 +1066,10 @@ int of_gpiochip_add(struct gpio_chip *chip)
 
 	of_node_get(np);
 
-	ret = of_gpiochip_scan_gpios(chip);
-	if (ret)
-		of_node_put(np);
+	for_each_available_child_of_node_scoped(np, child) {
+		if (of_property_read_bool(child, "gpio-hog"))
+			of_node_set_flag(child, OF_POPULATED);
+	}
 
 	return ret;
 }

drivers/gpio/gpiolib-of.h

@@ -10,6 +10,7 @@
 
 struct device_node;
 struct fwnode_handle;
+struct fwnode_reference_args;
 
 struct gpio_chip;
 struct gpio_desc;
@@ -24,6 +25,9 @@ int of_gpiochip_add(struct gpio_chip *gc);
 void of_gpiochip_remove(struct gpio_chip *gc);
 bool of_gpiochip_instance_match(struct gpio_chip *gc, unsigned int index);
 int of_gpio_count(const struct fwnode_handle *fwnode, const char *con_id);
+int of_gpiochip_get_lflags(struct gpio_chip *chip,
+			   struct fwnode_reference_args *gpiospec,
+			   unsigned long *lflags);
 #else
 static inline struct gpio_desc *of_find_gpio(struct device_node *np,
 					     const char *con_id,
@@ -44,6 +48,12 @@ static inline int of_gpio_count(const struct fwnode_handle *fwnode,
 {
 	return 0;
 }
+static inline int of_gpiochip_get_lflags(struct gpio_chip *chip,
+					 struct fwnode_reference_args *gpiospec,
+					 unsigned long *lflags)
+{
+	return -ENOENT;
+}
 #endif /* CONFIG_OF_GPIO */
 
 extern struct notifier_block gpio_of_notifier;