4 files changed, 106 insertions, 3 deletions

diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c
index 2b47f9388607..ccc449df3792 100644
--- a/drivers/gpio/gpiolib-of.c
+++ b/drivers/gpio/gpiolib-of.c
@@ -628,6 +628,10 @@ static int of_gpiochip_add_hog(struct gpio_chip *chip, struct device_node *hog)
 		ret = gpiod_hog(desc, name, lflags, dflags);
 		if (ret < 0)
 			return ret;
+
+#ifdef CONFIG_OF_DYNAMIC
+		desc->hog = hog;
+#endif
 	}
 
 	return 0;
@@ -655,11 +659,97 @@ static int of_gpiochip_scan_gpios(struct gpio_chip *chip)
 			of_node_put(np);
 			return ret;
 		}
+
+		of_node_set_flag(np, OF_POPULATED);
 	}
 
 	return 0;
 }
 
+#ifdef CONFIG_OF_DYNAMIC
+/**
+ * of_gpiochip_remove_hog - Remove all hogs in a hog device node
+ * @chip:	gpio chip to act on
+ * @hog:	device node describing the hogs
+ */
+static void of_gpiochip_remove_hog(struct gpio_chip *chip,
+				   struct device_node *hog)
+{
+	struct gpio_desc *descs = chip->gpiodev->descs;
+	unsigned int i;
+
+	for (i = 0; i < chip->ngpio; i++) {
+		if (test_bit(FLAG_IS_HOGGED, &descs[i].flags) &&
+		    descs[i].hog == hog)
+			gpiochip_free_own_desc(&descs[i]);
+	}
+}
+
+static int of_gpiochip_match_node(struct gpio_chip *chip, void *data)
+{
+	return chip->gpiodev->dev.of_node == data;
+}
+
+static struct gpio_chip *of_find_gpiochip_by_node(struct device_node *np)
+{
+	return gpiochip_find(np, of_gpiochip_match_node);
+}
+
+static int of_gpio_notify(struct notifier_block *nb, unsigned long action,
+			  void *arg)
+{
+	struct of_reconfig_data *rd = arg;
+	struct gpio_chip *chip;
+	int ret;
+
+	/*
+	 * This only supports adding and removing complete gpio-hog nodes.
+	 * Modifying an existing gpio-hog node is not supported (except for
+	 * changing its "status" property, which is treated the same as
+	 * addition/removal).
+	 */
+	switch (of_reconfig_get_state_change(action, arg)) {
+	case OF_RECONFIG_CHANGE_ADD:
+		if (!of_property_read_bool(rd->dn, "gpio-hog"))
+			return NOTIFY_OK;	/* not for us */
+
+		if (of_node_test_and_set_flag(rd->dn, OF_POPULATED))
+			return NOTIFY_OK;
+
+		chip = of_find_gpiochip_by_node(rd->dn->parent);
+		if (chip == NULL)
+			return NOTIFY_OK;	/* not for us */
+
+		ret = of_gpiochip_add_hog(chip, rd->dn);
+		if (ret < 0) {
+			pr_err("%s: failed to add hogs for %pOF\n", __func__,
+			       rd->dn);
+			of_node_clear_flag(rd->dn, OF_POPULATED);
+			return notifier_from_errno(ret);
+		}
+		break;
+
+	case OF_RECONFIG_CHANGE_REMOVE:
+		if (!of_node_check_flag(rd->dn, OF_POPULATED))
+			return NOTIFY_OK;	/* already depopulated */
+
+		chip = of_find_gpiochip_by_node(rd->dn->parent);
+		if (chip == NULL)
+			return NOTIFY_OK;	/* not for us */
+
+		of_gpiochip_remove_hog(chip, rd->dn);
+		of_node_clear_flag(rd->dn, OF_POPULATED);
+		break;
+	}
+
+	return NOTIFY_OK;
+}
+
+struct notifier_block gpio_of_notifier = {
+	.notifier_call = of_gpio_notify,
+};
+#endif /* CONFIG_OF_DYNAMIC */
+
 /**
  * of_gpio_simple_xlate - translate gpiospec to the GPIO number and flags
  * @gc:		pointer to the gpio_chip structure
diff --git a/drivers/gpio/gpiolib-of.h b/drivers/gpio/gpiolib-of.h
index 9768831b1fe2..ed26664f1537 100644
--- a/drivers/gpio/gpiolib-of.h
+++ b/drivers/gpio/gpiolib-of.h
@@ -35,4 +35,6 @@ static inline bool of_gpio_need_valid_mask(const struct gpio_chip *gc)
 }
 #endif /* CONFIG_OF_GPIO */
 
+extern struct notifier_block gpio_of_notifier;
+
 #endif /* GPIOLIB_OF_H */
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 2c3a9c1c76be..9ad86477af9c 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -3103,6 +3103,9 @@ static bool gpiod_free_commit(struct gpio_desc *desc)
 		clear_bit(FLAG_PULL_DOWN, &desc->flags);
 		clear_bit(FLAG_BIAS_DISABLE, &desc->flags);
 		clear_bit(FLAG_IS_HOGGED, &desc->flags);
+#ifdef CONFIG_OF_DYNAMIC
+		desc->hog = NULL;
+#endif
 		ret = true;
 	}
 
@@ -5281,10 +5284,15 @@ static int __init gpiolib_dev_init(void)
 	if (ret < 0) {
 		pr_err("gpiolib: failed to allocate char dev region\n");
 		bus_unregister(&gpio_bus_type);
-	} else {
-		gpiolib_initialized = true;
-		gpiochip_setup_devs();
+		return ret;
 	}
+
+	gpiolib_initialized = true;
+	gpiochip_setup_devs();
+
+	if (IS_ENABLED(CONFIG_OF_DYNAMIC))
+		WARN_ON(of_reconfig_notifier_register(&gpio_of_notifier));
+
 	return ret;
 }
 core_initcall(gpiolib_dev_init);
diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h
index 5ab90746b519..853ce681b4a4 100644
--- a/drivers/gpio/gpiolib.h
+++ b/drivers/gpio/gpiolib.h
@@ -120,6 +120,9 @@ struct gpio_desc {
 	const char		*label;
 	/* Name of the GPIO */
 	const char		*name;
+#ifdef CONFIG_OF_DYNAMIC
+	struct device_node	*hog;
+#endif
 };
 
 int gpiod_request(struct gpio_desc *desc, const char *label);