3 files changed, 219 insertions, 19 deletions

diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c
index 8cad8e400b44..468d76ac1e84 100644
--- a/drivers/gpio/gpiolib-of.c
+++ b/drivers/gpio/gpiolib-of.c
@@ -22,6 +22,7 @@
 #include <linux/of_gpio.h>
 #include <linux/pinctrl/pinctrl.h>
 #include <linux/slab.h>
+#include <linux/gpio/machine.h>
 
 #include "gpiolib.h"
 
@@ -117,6 +118,114 @@ int of_get_named_gpio_flags(struct device_node *np, const char *list_name,
 EXPORT_SYMBOL(of_get_named_gpio_flags);
 
 /**
+ * of_get_gpio_hog() - Get a GPIO hog descriptor, names and flags for GPIO API
+ * @np:		device node to get GPIO from
+ * @name:	GPIO line name
+ * @lflags:	gpio_lookup_flags - returned from of_find_gpio() or
+ *		of_get_gpio_hog()
+ * @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_get_gpio_hog(struct device_node *np,
+				  const char **name,
+				  enum gpio_lookup_flags *lflags,
+				  enum gpiod_flags *dflags)
+{
+	struct device_node *chip_np;
+	enum of_gpio_flags xlate_flags;
+	struct gpio_desc *desc;
+	struct gg_data gg_data = {
+		.flags = &xlate_flags,
+	};
+	u32 tmp;
+	int i, ret;
+
+	chip_np = np->parent;
+	if (!chip_np)
+		return ERR_PTR(-EINVAL);
+
+	xlate_flags = 0;
+	*lflags = 0;
+	*dflags = 0;
+
+	ret = of_property_read_u32(chip_np, "#gpio-cells", &tmp);
+	if (ret)
+		return ERR_PTR(ret);
+
+	if (tmp > MAX_PHANDLE_ARGS)
+		return ERR_PTR(-EINVAL);
+
+	gg_data.gpiospec.args_count = tmp;
+	gg_data.gpiospec.np = chip_np;
+	for (i = 0; i < tmp; i++) {
+		ret = of_property_read_u32_index(np, "gpios", i,
+					   &gg_data.gpiospec.args[i]);
+		if (ret)
+			return ERR_PTR(ret);
+	}
+
+	gpiochip_find(&gg_data, of_gpiochip_find_and_xlate);
+	if (!gg_data.out_gpio) {
+		if (np->parent == np)
+			return ERR_PTR(-ENXIO);
+		else
+			return ERR_PTR(-EINVAL);
+	}
+
+	if (xlate_flags & OF_GPIO_ACTIVE_LOW)
+		*lflags |= GPIO_ACTIVE_LOW;
+
+	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 (%s): no hogging state specified, bailing out\n",
+			desc_to_gpio(gg_data.out_gpio), np->name);
+		return ERR_PTR(-EINVAL);
+	}
+
+	if (name && of_property_read_string(np, "line-name", name))
+		*name = np->name;
+
+	desc = gg_data.out_gpio;
+
+	return desc;
+}
+
+/**
+ * of_gpiochip_scan_hogs - Scan gpio-controller and apply GPIO hog as requested
+ * @chip:	gpio chip to act on
+ *
+ * This is only used by of_gpiochip_add to request/set GPIO initial
+ * configuration.
+ */
+static void of_gpiochip_scan_hogs(struct gpio_chip *chip)
+{
+	struct gpio_desc *desc = NULL;
+	struct device_node *np;
+	const char *name;
+	enum gpio_lookup_flags lflags;
+	enum gpiod_flags dflags;
+
+	for_each_child_of_node(chip->of_node, np) {
+		if (!of_property_read_bool(np, "gpio-hog"))
+			continue;
+
+		desc = of_get_gpio_hog(np, &name, &lflags, &dflags);
+		if (IS_ERR(desc))
+			continue;
+
+		if (gpiod_hog(desc, name, lflags, dflags))
+			continue;
+	}
+}
+
+/**
  * of_gpio_simple_xlate - translate gpio_spec to the GPIO number and flags
  * @gc:		pointer to the gpio_chip structure
  * @np:		device node of the GPIO chip
@@ -325,6 +434,8 @@ void of_gpiochip_add(struct gpio_chip *chip)
 
 	of_gpiochip_add_pin_range(chip);
 	of_node_get(chip->of_node);
+
+	of_gpiochip_scan_hogs(chip);
 }
 
 void of_gpiochip_remove(struct gpio_chip *chip)
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 1ca9295b2c10..15837263dbb3 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -315,6 +315,7 @@ EXPORT_SYMBOL_GPL(gpiochip_add);
 
 /* Forward-declaration */
 static void gpiochip_irqchip_remove(struct gpio_chip *gpiochip);
+static void gpiochip_free_hogs(struct gpio_chip *chip);
 
 /**
  * gpiochip_remove() - unregister a gpio_chip
@@ -333,6 +334,7 @@ void gpiochip_remove(struct gpio_chip *chip)
 
 	acpi_gpiochip_remove(chip);
 	gpiochip_remove_pin_ranges(chip);
+	gpiochip_free_hogs(chip);
 	of_gpiochip_remove(chip);
 
 	spin_lock_irqsave(&gpio_lock, flags);
@@ -866,6 +868,7 @@ static bool __gpiod_free(struct gpio_desc *desc)
 		clear_bit(FLAG_REQUESTED, &desc->flags);
 		clear_bit(FLAG_OPEN_DRAIN, &desc->flags);
 		clear_bit(FLAG_OPEN_SOURCE, &desc->flags);
+		clear_bit(FLAG_IS_HOGGED, &desc->flags);
 		ret = true;
 	}
 
@@ -1840,6 +1843,47 @@ struct gpio_desc *__must_check __gpiod_get_optional(struct device *dev,
 }
 EXPORT_SYMBOL_GPL(__gpiod_get_optional);
 
+
+/**
+ * gpiod_configure_flags - helper function to configure a given GPIO
+ * @desc:	gpio whose value will be assigned
+ * @con_id:	function within the GPIO consumer
+ * @lflags:	gpio_lookup_flags - returned from of_find_gpio() or
+ *		of_get_gpio_hog()
+ * @dflags:	gpiod_flags - optional GPIO initialization flags
+ *
+ * Return 0 on success, -ENOENT if no GPIO has been assigned to the
+ * requested function and/or index, or another IS_ERR() code if an error
+ * occurred while trying to acquire the GPIO.
+ */
+static int gpiod_configure_flags(struct gpio_desc *desc, const char *con_id,
+		unsigned long lflags, enum gpiod_flags dflags)
+{
+	int status;
+
+	if (lflags & GPIO_ACTIVE_LOW)
+		set_bit(FLAG_ACTIVE_LOW, &desc->flags);
+	if (lflags & GPIO_OPEN_DRAIN)
+		set_bit(FLAG_OPEN_DRAIN, &desc->flags);
+	if (lflags & GPIO_OPEN_SOURCE)
+		set_bit(FLAG_OPEN_SOURCE, &desc->flags);
+
+	/* No particular flag request, return here... */
+	if (!(dflags & GPIOD_FLAGS_BIT_DIR_SET)) {
+		pr_debug("no flags found for %s\n", con_id);
+		return 0;
+	}
+
+	/* Process flags */
+	if (dflags & GPIOD_FLAGS_BIT_DIR_OUT)
+		status = gpiod_direction_output(desc,
+					      dflags & GPIOD_FLAGS_BIT_DIR_VAL);
+	else
+		status = gpiod_direction_input(desc);
+
+	return status;
+}
+
 /**
  * gpiod_get_index - obtain a GPIO from a multi-index GPIO function
  * @dev:	GPIO consumer, can be NULL for system-global GPIOs
@@ -1889,28 +1933,10 @@ struct gpio_desc *__must_check __gpiod_get_index(struct device *dev,
 	}
 
 	status = gpiod_request(desc, con_id);
-
 	if (status < 0)
 		return ERR_PTR(status);
 
-	if (lookupflags & GPIO_ACTIVE_LOW)
-		set_bit(FLAG_ACTIVE_LOW, &desc->flags);
-	if (lookupflags & GPIO_OPEN_DRAIN)
-		set_bit(FLAG_OPEN_DRAIN, &desc->flags);
-	if (lookupflags & GPIO_OPEN_SOURCE)
-		set_bit(FLAG_OPEN_SOURCE, &desc->flags);
-
-	/* No particular flag request, return here... */
-	if (!(flags & GPIOD_FLAGS_BIT_DIR_SET))
-		return desc;
-
-	/* Process flags */
-	if (flags & GPIOD_FLAGS_BIT_DIR_OUT)
-		status = gpiod_direction_output(desc,
-					      flags & GPIOD_FLAGS_BIT_DIR_VAL);
-	else
-		status = gpiod_direction_input(desc);
-
+	status = gpiod_configure_flags(desc, con_id, lookupflags, flags);
 	if (status < 0) {
 		dev_dbg(dev, "setup of GPIO %s failed\n", con_id);
 		gpiod_put(desc);
@@ -2006,6 +2032,66 @@ struct gpio_desc *__must_check __gpiod_get_index_optional(struct device *dev,
 EXPORT_SYMBOL_GPL(__gpiod_get_index_optional);
 
 /**
+ * gpiod_hog - Hog the specified GPIO desc given the provided flags
+ * @desc:	gpio whose value will be assigned
+ * @name:	gpio line name
+ * @lflags:	gpio_lookup_flags - returned from of_find_gpio() or
+ *		of_get_gpio_hog()
+ * @dflags:	gpiod_flags - optional GPIO initialization flags
+ */
+int gpiod_hog(struct gpio_desc *desc, const char *name,
+	      unsigned long lflags, enum gpiod_flags dflags)
+{
+	struct gpio_chip *chip;
+	struct gpio_desc *local_desc;
+	int hwnum;
+	int status;
+
+	chip = gpiod_to_chip(desc);
+	hwnum = gpio_chip_hwgpio(desc);
+
+	local_desc = gpiochip_request_own_desc(chip, hwnum, name);
+	if (IS_ERR(local_desc)) {
+		pr_debug("requesting own GPIO %s failed\n", name);
+		return PTR_ERR(local_desc);
+	}
+
+	status = gpiod_configure_flags(desc, name, lflags, dflags);
+	if (status < 0) {
+		pr_debug("setup of GPIO %s failed\n", name);
+		gpiochip_free_own_desc(desc);
+		return status;
+	}
+
+	/* Mark GPIO as hogged so it can be identified and removed later */
+	set_bit(FLAG_IS_HOGGED, &desc->flags);
+
+	pr_info("GPIO line %d (%s) hogged as %s%s\n",
+		desc_to_gpio(desc), name,
+		(dflags&GPIOD_FLAGS_BIT_DIR_OUT) ? "output" : "input",
+		(dflags&GPIOD_FLAGS_BIT_DIR_OUT) ?
+		  (dflags&GPIOD_FLAGS_BIT_DIR_VAL) ? "/high" : "/low":"");
+
+	return 0;
+}
+
+/**
+ * gpiochip_free_hogs - Scan gpio-controller chip and release GPIO hog
+ * @chip:	gpio chip to act on
+ *
+ * This is only used by of_gpiochip_remove to free hogged gpios
+ */
+static void gpiochip_free_hogs(struct gpio_chip *chip)
+{
+	int id;
+
+	for (id = 0; id < chip->ngpio; id++) {
+		if (test_bit(FLAG_IS_HOGGED, &chip->desc[id].flags))
+			gpiochip_free_own_desc(&chip->desc[id]);
+	}
+}
+
+/**
  * gpiod_put - dispose of a GPIO descriptor
  * @desc:	GPIO descriptor to dispose of
  *
diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h
index 550a5eafbd38..cadba26c45a6 100644
--- a/drivers/gpio/gpiolib.h
+++ b/drivers/gpio/gpiolib.h
@@ -78,6 +78,7 @@ struct gpio_desc {
 #define FLAG_OPEN_SOURCE 8	/* Gpio is open source type */
 #define FLAG_USED_AS_IRQ 9	/* GPIO is connected to an IRQ */
 #define FLAG_SYSFS_DIR	10	/* show sysfs direction attribute */
+#define FLAG_IS_HOGGED	11	/* GPIO is hogged */
 
 #define ID_SHIFT	16	/* add new flags before this one */
 
@@ -89,6 +90,8 @@ struct gpio_desc {
 
 int gpiod_request(struct gpio_desc *desc, const char *label);
 void gpiod_free(struct gpio_desc *desc);
+int gpiod_hog(struct gpio_desc *desc, const char *name,
+		unsigned long lflags, enum gpiod_flags dflags);
 
 /*
  * Return the GPIO number of the passed descriptor relative to its chip