// SPDX-License-Identifier: GPL-2.0+
/*
 * OF helpers for the GPIO API
 *
 * Copyright (c) 2007-2008  MontaVista Software, Inc.
 *
 * Author: Anton Vorontsov <avorontsov@ru.mvista.com>
 */

#include <linux/device.h>
#include <linux/err.h>
#include <linux/errno.h>
#include <linux/module.h>
#include <linux/io.h>
#include <linux/gpio/consumer.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_gpio.h>
#include <linux/pinctrl/pinctrl.h>
#include <linux/slab.h>
#include <linux/gpio/machine.h>

#include "gpiolib.h"
#include "gpiolib-of.h"

/**
 * of_gpio_spi_cs_get_count() - special GPIO counting for SPI
 * @dev:    Consuming device
 * @con_id: Function within the GPIO consumer
 *
 * Some elder GPIO controllers need special quirks. Currently we handle
 * the Freescale and PPC GPIO controller with bindings that doesn't use the
 * established "cs-gpios" for chip selects but instead rely on
 * "gpios" for the chip select lines. If we detect this, we redirect
 * the counting of "cs-gpios" to count "gpios" transparent to the
 * driver.
 */
static int of_gpio_spi_cs_get_count(struct device *dev, const char *con_id)
{
        struct device_node *np = dev->of_node;

        if (!IS_ENABLED(CONFIG_SPI_MASTER))
                return 0;
        if (!con_id || strcmp(con_id, "cs"))
                return 0;
        if (!of_device_is_compatible(np, "fsl,spi") &&
            !of_device_is_compatible(np, "aeroflexgaisler,spictrl") &&
            !of_device_is_compatible(np, "ibm,ppc4xx-spi"))
                return 0;
        return of_gpio_named_count(np, "gpios");
}

/*
 * This is used by external users of of_gpio_count() from <linux/of_gpio.h>
 *
 * FIXME: get rid of those external users by converting them to GPIO
 * descriptors and let them all use gpiod_count()
 */
int of_gpio_get_count(struct device *dev, const char *con_id)
{
        int ret;
        char propname[32];
        unsigned int i;

        ret = of_gpio_spi_cs_get_count(dev, con_id);
        if (ret > 0)
                return ret;

        for (i = 0; i < ARRAY_SIZE(gpio_suffixes); i++) {
                if (con_id)
                        snprintf(propname, sizeof(propname), "%s-%s",
                                 con_id, gpio_suffixes[i]);
                else
                        snprintf(propname, sizeof(propname), "%s",
                                 gpio_suffixes[i]);

                ret = of_gpio_named_count(dev->of_node, propname);
                if (ret > 0)
                        break;
        }
        return ret ? ret : -ENOENT;
}

static int of_gpiochip_match_node_and_xlate(struct gpio_chip *chip, void *data)
{
        struct of_phandle_args *gpiospec = data;

        return chip->gpiodev->dev.of_node == gpiospec->np &&
                                chip->of_xlate &&
                                chip->of_xlate(chip, gpiospec, NULL) >= 0;
}

static struct gpio_chip *of_find_gpiochip_by_xlate(
                                        struct of_phandle_args *gpiospec)
{
        return gpiochip_find(gpiospec, of_gpiochip_match_node_and_xlate);
}

static struct gpio_desc *of_xlate_and_get_gpiod_flags(struct gpio_chip *chip,
                                        struct of_phandle_args *gpiospec,
                                        enum of_gpio_flags *flags)
{
        int ret;

        if (chip->of_gpio_n_cells != gpiospec->args_count)
                return ERR_PTR(-EINVAL);

        ret = chip->of_xlate(chip, gpiospec, flags);
        if (ret < 0)
                return ERR_PTR(ret);

        return gpiochip_get_desc(chip, ret);
}

/**
 * of_gpio_need_valid_mask() - figure out if the OF GPIO driver needs
 * to set the .valid_mask
 * @gc: the target gpio_chip
 *
 * Return: true if the valid mask needs to be set
 */
bool of_gpio_need_valid_mask(const struct gpio_chip *gc)
{
        int size;
        const struct device_node *np = gc->of_node;

        size = of_property_count_u32_elems(np,  "gpio-reserved-ranges");
        if (size > 0 && size % 2 == 0)
                return true;
        return false;
}

static void of_gpio_flags_quirks(const struct device_node *np,
                                 const char *propname,
                                 enum of_gpio_flags *flags,
                                 int index)
{
        /*
         * Some GPIO fixed regulator quirks.
         * Note that active low is the default.
         */
        if (IS_ENABLED(CONFIG_REGULATOR) &&
            (of_device_is_compatible(np, "regulator-fixed") ||
             of_device_is_compatible(np, "reg-fixed-voltage") ||
             (!(strcmp(propname, "enable-gpio") &&
                strcmp(propname, "enable-gpios")) &&
              of_device_is_compatible(np, "regulator-gpio")))) {
                bool active_low = !of_property_read_bool(np,
                                                         "enable-active-high");
                /*
                 * The regulator GPIO handles are specified such that the
                 * presence or absence of "enable-active-high" solely controls
                 * the polarity of the GPIO line. Any phandle flags must
                 * be actively ignored.
                 */
                if ((*flags & OF_GPIO_ACTIVE_LOW) && !active_low) {
                        pr_warn("%s GPIO handle specifies active low - ignored\n",
                                of_node_full_name(np));
                        *flags &= ~OF_GPIO_ACTIVE_LOW;
                }
                if (active_low)
                        *flags |= OF_GPIO_ACTIVE_LOW;
        }
        /*
         * Legacy open drain handling for fixed voltage regulators.
         */
        if (IS_ENABLED(CONFIG_REGULATOR) &&
            of_device_is_compatible(np, "reg-fixed-voltage") &&
            of_property_read_bool(np, "gpio-open-drain")) {
                *flags |= (OF_GPIO_SINGLE_ENDED | OF_GPIO_OPEN_DRAIN);
                pr_info("%s uses legacy open drain flag - update the DTS if you can\n",
                        of_node_full_name(np));
        }

        /*
         * Legacy handling of SPI active high chip select. If we have a
         * property named "cs-gpios" we need to inspect the child node
         * to determine if the flags should have inverted semantics.
         */
        if (IS_ENABLED(CONFIG_SPI_MASTER) && !strcmp(propname, "cs-gpios") &&
            of_property_read_bool(np, "cs-gpios")) {
                struct device_node *child;
                u32 cs;
                int ret;

                for_each_child_of_node(np, child) {
                        ret = of_property_read_u32(child, "reg", &cs);
                        if (ret)
                                continue;
                        if (cs == index) {
                                /*
                                 * SPI children have active low chip selects
                                 * by default. This can be specified negatively
                                 * by just omitting "spi-cs-high" in the
                                 * device node, or actively by tagging on
                                 * GPIO_ACTIVE_LOW as flag in the device
                                 * tree. If the line is simultaneously
                                 * tagged as active low in the device tree
                                 * and has the "spi-cs-high" set, we get a
                                 * conflict and the "spi-cs-high" flag will
                                 * take precedence.
                                 */
                                if (of_property_read_bool(child, "spi-cs-high")) {
                                        if (*flags & OF_GPIO_ACTIVE_LOW) {
                                                pr_warn("%s GPIO handle specifies active low - ignored\n",
                                                        of_node_full_name(child));
                                                *flags &= ~OF_GPIO_ACTIVE_LOW;
                                        }
                                } else {
                                        if (!(*flags & OF_GPIO_ACTIVE_LOW))
                                                pr_info("%s enforce active low on chipselect handle\n",
                                                        of_node_full_name(child));
                                        *flags |= OF_GPIO_ACTIVE_LOW;
                                }
                                of_node_put(child);
                                break;
                        }
                }
        }

        /* Legacy handling of stmmac's active-low PHY reset line */
        if (IS_ENABLED(CONFIG_STMMAC_ETH) &&
            !strcmp(propname, "snps,reset-gpio") &&
            of_property_read_bool(np, "snps,reset-active-low"))
                *flags |= OF_GPIO_ACTIVE_LOW;
}

/**
 * of_get_named_gpiod_flags() - Get a GPIO descriptor and flags for GPIO API
 * @np:         device node to get GPIO from
 * @propname:   property name containing gpio specifier(s)
 * @index:      index of the GPIO
 * @flags:      a flags pointer to fill in
 *
 * Returns GPIO descriptor to use with Linux GPIO API, or one of the errno
 * value on the error condition. If @flags is not NULL the function also fills
 * in flags for the GPIO.
 */
static struct gpio_desc *of_get_named_gpiod_flags(const struct device_node *np,
                     const char *propname, int index, enum of_gpio_flags *flags)
{
        struct of_phandle_args gpiospec;
        struct gpio_chip *chip;
        struct gpio_desc *desc;
        int ret;

        ret = of_parse_phandle_with_args_map(np, propname, "gpio", index,
                                             &gpiospec);
        if (ret) {
                pr_debug("%s: can't parse '%s' property of node '%pOF[%d]'\n",
                        __func__, propname, np, index);
                return ERR_PTR(ret);
        }

        chip = of_find_gpiochip_by_xlate(&gpiospec);
        if (!chip) {
                desc = ERR_PTR(-EPROBE_DEFER);
                goto out;
        }

        desc = of_xlate_and_get_gpiod_flags(chip, &gpiospec, flags);
        if (IS_ERR(desc))
                goto out;

        if (flags)
                of_gpio_flags_quirks(np, propname, flags, index);

        pr_debug("%s: parsed '%s' property of node '%pOF[%d]' - status (%d)\n",
                 __func__, propname, np, index,
                 PTR_ERR_OR_ZERO(desc));

out:
        of_node_put(gpiospec.np);

        return desc;
}

int of_get_named_gpio_flags(const struct device_node *np, const char *list_name,
                            int index, enum of_gpio_flags *flags)
{
        struct gpio_desc *desc;

        desc = of_get_named_gpiod_flags(np, list_name, index, flags);

        if (IS_ERR(desc))
                return PTR_ERR(desc);
        else
                return desc_to_gpio(desc);
}
EXPORT_SYMBOL_GPL(of_get_named_gpio_flags);

/**
 * gpiod_get_from_of_node() - obtain a GPIO from an OF node
 * @node:       handle of the OF node
 * @propname:   name of the DT property representing the GPIO
 * @index:      index of the GPIO to obtain for the consumer
 * @dflags:     GPIO initialization flags
 * @label:      label to attach to the requested GPIO
 *
 * Returns:
 * On successful request the GPIO pin is configured in accordance with
 * provided @dflags.
 *
 * In case of error an ERR_PTR() is returned.
 */
struct gpio_desc *gpiod_get_from_of_node(const struct device_node *node,
                                         const char *propname, int index,
                                         enum gpiod_flags dflags,
                                         const char *label)
{
        unsigned long lflags = GPIO_LOOKUP_FLAGS_DEFAULT;
        struct gpio_desc *desc;
        enum of_gpio_flags flags;
        bool active_low = false;
        bool single_ended = false;
        bool open_drain = false;
        bool transitory = false;
        int ret;

        desc = of_get_named_gpiod_flags(node, propname,
                                        index, &flags);

        if (!desc || IS_ERR(desc)) {
                return desc;
        }

        active_low = flags & OF_GPIO_ACTIVE_LOW;
        single_ended = flags & OF_GPIO_SINGLE_ENDED;
        open_drain = flags & OF_GPIO_OPEN_DRAIN;
        transitory = flags & OF_GPIO_TRANSITORY;

        ret = gpiod_request(desc, label);
        if (ret == -EBUSY && (dflags & GPIOD_FLAGS_BIT_NONEXCLUSIVE))
                return desc;
        if (ret)
                return ERR_PTR(ret);

        if (active_low)
                lflags |= GPIO_ACTIVE_LOW;

        if (single_ended) {
                if (open_drain)
                        lflags |= GPIO_OPEN_DRAIN;
                else
                        lflags |= GPIO_OPEN_SOURCE;
        }

        if (transitory)
                lflags |= GPIO_TRANSITORY;

        if (flags & OF_GPIO_PULL_UP)
                lflags |= GPIO_PULL_UP;

        if (flags & OF_GPIO_PULL_DOWN)
                lflags |= GPIO_PULL_DOWN;

        ret = gpiod_configure_flags(desc, propname, lflags, dflags);
        if (ret < 0) {
                gpiod_put(desc);
                return ERR_PTR(ret);
        }

        return desc;
}
EXPORT_SYMBOL_GPL(gpiod_get_from_of_node);

/*
 * The SPI GPIO bindings happened before we managed to establish that GPIO
 * properties should be named "foo-gpios" so we have this special kludge for
 * them.
 */
static struct gpio_desc *of_find_spi_gpio(struct device *dev, const char *con_id,
                                          enum of_gpio_flags *of_flags)
{
        char prop_name[32]; /* 32 is max size of property name */
        const struct device_node *np = dev->of_node;
        struct gpio_desc *desc;

        /*
         * Hopefully the compiler stubs the rest of the function if this
         * is false.
         */
        if (!IS_ENABLED(CONFIG_SPI_MASTER))
                return ERR_PTR(-ENOENT);

        /* Allow this specifically for "spi-gpio" devices */
        if (!of_device_is_compatible(np, "spi-gpio") || !con_id)
                return ERR_PTR(-ENOENT);

        /* Will be "gpio-sck", "gpio-mosi" or "gpio-miso" */
        snprintf(prop_name, sizeof(prop_name), "%s-%s", "gpio", con_id);

        desc = of_get_named_gpiod_flags(np, prop_name, 0, of_flags);
        return desc;
}

/*
 * The old Freescale bindings use simply "gpios" as name for the chip select
 * lines rather than "cs-gpios" like all other SPI hardware. Account for this
 * with a special quirk.
 */
static struct gpio_desc *of_find_spi_cs_gpio(struct device *dev,
                                             const char *con_id,
                                             unsigned int idx,
                                             unsigned long *flags)
{
        const struct device_node *np = dev->of_node;

        if (!IS_ENABLED(CONFIG_SPI_MASTER))
                return ERR_PTR(-ENOENT);

        /* Allow this specifically for Freescale and PPC devices */
        if (!of_device_is_compatible(np, "fsl,spi") &&
            !of_device_is_compatible(np, "aeroflexgaisler,spictrl") &&
            !of_device_is_compatible(np, "ibm,ppc4xx-spi"))
                return ERR_PTR(-ENOENT);
        /* Allow only if asking for "cs-gpios" */
        if (!con_id || strcmp(con_id, "cs"))
                return ERR_PTR(-ENOENT);

        /*
         * While all other SPI controllers use "cs-gpios" the Freescale
         * uses just "gpios" so translate to that when "cs-gpios" is
         * requested.
         */
        return of_find_gpio(dev, NULL, idx, flags);
}

/*
 * Some regulator bindings happened before we managed to establish that GPIO
 * properties should be named "foo-gpios" so we have this special kludge for
 * them.
 */
static struct gpio_desc *of_find_regulator_gpio(struct device *dev, const char *con_id,
                                                enum of_gpio_flags *of_flags)
{
        /* These are the connection IDs we accept as legacy GPIO phandles */
        const char *whitelist[] = {
                "wlf,ldoena", /* Arizona */
                "wlf,ldo1ena", /* WM8994 */
                "wlf,ldo2ena", /* WM8994 */
        };
        const struct device_node *np = dev->of_node;
        struct gpio_desc *desc;
        int i;

        if (!IS_ENABLED(CONFIG_REGULATOR))
                return ERR_PTR(-ENOENT);

        if (!con_id)
                return ERR_PTR(-ENOENT);

        i = match_string(whitelist, ARRAY_SIZE(whitelist), con_id);
        if (i < 0)
                return ERR_PTR(-ENOENT);

        desc = of_get_named_gpiod_flags(np, con_id, 0, of_flags);
        return desc;
}

static struct gpio_desc *of_find_arizona_gpio(struct device *dev,
                                              const char *con_id,
                                              enum of_gpio_flags *of_flags)
{
        if (!IS_ENABLED(CONFIG_MFD_ARIZONA))
                return ERR_PTR(-ENOENT);

        if (!con_id || strcmp(con_id, "wlf,reset"))
                return ERR_PTR(-ENOENT);

        return of_get_named_gpiod_flags(dev->of_node, con_id, 0, of_flags);
}

static struct gpio_desc *of_find_usb_gpio(struct device *dev,
                                          const char *con_id,
                                          enum of_gpio_flags *of_flags)
{
        /*
         * Currently this USB quirk is only for the Fairchild FUSB302 host which is using
         * an undocumented DT GPIO line named "fcs,int_n" without the compulsory "-gpios"
         * suffix.
         */
        if (!IS_ENABLED(CONFIG_TYPEC_FUSB302))
                return ERR_PTR(-ENOENT);

        if (!con_id || strcmp(con_id, "fcs,int_n"))
                return ERR_PTR(-ENOENT);

        return of_get_named_gpiod_flags(dev->of_node, con_id, 0, of_flags);
}

struct gpio_desc *of_find_gpio(struct device *dev, const char *con_id,
                               unsigned int idx, unsigned long *flags)
{
        char prop_name[32]; /* 32 is max size of property name */
        enum of_gpio_flags of_flags;
        struct gpio_desc *desc;
        unsigned int i;

        /* Try GPIO property "foo-gpios" and "foo-gpio" */
        for (i = 0; i < ARRAY_SIZE(gpio_suffixes); i++) {
                if (con_id)
                        snprintf(prop_name, sizeof(prop_name), "%s-%s", con_id,
                                 gpio_suffixes[i]);
                else
                        snprintf(prop_name, sizeof(prop_name), "%s",
                                 gpio_suffixes[i]);

                desc = of_get_named_gpiod_flags(dev->of_node, prop_name, idx,
                                                &of_flags);

                if (!gpiod_not_found(desc))
                        break;
        }

        if (gpiod_not_found(desc)) {
                /* Special handling for SPI GPIOs if used */
                desc = of_find_spi_gpio(dev, con_id, &of_flags);
        }

        if (gpiod_not_found(desc)) {
                /* This quirk looks up flags and all */
                desc = of_find_spi_cs_gpio(dev, con_id, idx, flags);
                if (!IS_ERR(desc))
                        return desc;
        }

        if (gpiod_not_found(desc)) {
                /* Special handling for regulator GPIOs if used */
                desc = of_find_regulator_gpio(dev, con_id, &of_flags);
        }

        if (gpiod_not_found(desc))
                desc = of_find_arizona_gpio(dev, con_id, &of_flags);

        if (gpiod_not_found(desc))
                desc = of_find_usb_gpio(dev, con_id, &of_flags);

        if (IS_ERR(desc))
                return desc;

        if (of_flags & OF_GPIO_ACTIVE_LOW)
                *flags |= GPIO_ACTIVE_LOW;

        if (of_flags & OF_GPIO_SINGLE_ENDED) {
                if (of_flags & OF_GPIO_OPEN_DRAIN)
                        *flags |= GPIO_OPEN_DRAIN;
                else
                        *flags |= GPIO_OPEN_SOURCE;
        }

        if (of_flags & OF_GPIO_TRANSITORY)
                *flags |= GPIO_TRANSITORY;

        if (of_flags & OF_GPIO_PULL_UP)
                *flags |= GPIO_PULL_UP;
        if (of_flags & OF_GPIO_PULL_DOWN)
                *flags |= GPIO_PULL_DOWN;

        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)
{
        struct device_node *chip_np;
        enum of_gpio_flags xlate_flags;
        struct of_phandle_args gpiospec;
        struct gpio_desc *desc;
        unsigned int i;
        u32 tmp;
        int ret;

        chip_np = chip->of_node;
        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);

        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);
        }

        desc = of_xlate_and_get_gpiod_flags(chip, &gpiospec, &xlate_flags);
        if (IS_ERR(desc))
                return desc;

        if (xlate_flags & OF_GPIO_ACTIVE_LOW)
                *lflags |= GPIO_ACTIVE_LOW;
        if (xlate_flags & OF_GPIO_TRANSITORY)
                *lflags |= GPIO_TRANSITORY;
        if (xlate_flags & OF_GPIO_PULL_UP)
                *lflags |= GPIO_PULL_UP;
        if (xlate_flags & OF_GPIO_PULL_DOWN)
                *lflags |= GPIO_PULL_DOWN;

        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 error if it fails otherwise 0 on success.
 */
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
                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.
 * It returns error if it fails otherwise 0 on success.
 */
static int of_gpiochip_scan_gpios(struct gpio_chip *chip)
{
        struct device_node *np;
        int ret;

        for_each_available_child_of_node(chip->of_node, np) {
                if (!of_property_read_bool(np, "gpio-hog"))
                        continue;

                ret = of_gpiochip_add_hog(chip, np);
                if (ret < 0) {
                        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
 * @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).
 */
static int of_gpio_simple_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_mm_gpiochip_add_data - Add memory mapped GPIO chip (bank)
 * @np:         device node of the GPIO chip
 * @mm_gc:      pointer to the of_mm_gpio_chip allocated structure
 * @data:       driver data to store in the struct gpio_chip
 *
 * To use this function you should allocate and fill mm_gc with:
 *
 * 1) In the gpio_chip structure:
 *    - all the callbacks
 *    - of_gpio_n_cells
 *    - of_xlate callback (optional)
 *
 * 3) In the of_mm_gpio_chip structure:
 *    - save_regs callback (optional)
 *
 * If succeeded, this function will map bank's memory and will
 * do all necessary work for you. Then you'll able to use .regs
 * to manage GPIOs from the callbacks.
 */
int of_mm_gpiochip_add_data(struct device_node *np,
                            struct of_mm_gpio_chip *mm_gc,
                            void *data)
{
        int ret = -ENOMEM;
        struct gpio_chip *gc = &mm_gc->gc;

        gc->label = kasprintf(GFP_KERNEL, "%pOF", np);
        if (!gc->label)
                goto err0;

        mm_gc->regs = of_iomap(np, 0);
        if (!mm_gc->regs)
                goto err1;

        gc->base = -1;

        if (mm_gc->save_regs)
                mm_gc->save_regs(mm_gc);

        mm_gc->gc.of_node = np;

        ret = gpiochip_add_data(gc, data);
        if (ret)
                goto err2;

        return 0;
err2:
        iounmap(mm_gc->regs);
err1:
        kfree(gc->label);
err0:
        pr_err("%pOF: GPIO chip registration failed with status %d\n", np, ret);
        return ret;
}
EXPORT_SYMBOL_GPL(of_mm_gpiochip_add_data);

/**
 * of_mm_gpiochip_remove - Remove memory mapped GPIO chip (bank)
 * @mm_gc:      pointer to the of_mm_gpio_chip allocated structure
 */
void of_mm_gpiochip_remove(struct of_mm_gpio_chip *mm_gc)
{
        struct gpio_chip *gc = &mm_gc->gc;

        if (!mm_gc)
                return;

        gpiochip_remove(gc);
        iounmap(mm_gc->regs);
        kfree(gc->label);
}
EXPORT_SYMBOL_GPL(of_mm_gpiochip_remove);

static void of_gpiochip_init_valid_mask(struct gpio_chip *chip)
{
        int len, i;
        u32 start, count;
        struct device_node *np = chip->of_node;

        len = of_property_count_u32_elems(np,  "gpio-reserved-ranges");
        if (len < 0 || len % 2 != 0)
                return;

        for (i = 0; i < len; i += 2) {
                of_property_read_u32_index(np, "gpio-reserved-ranges",
                                           i, &start);
                of_property_read_u32_index(np, "gpio-reserved-ranges",
                                           i + 1, &count);
                if (start >= chip->ngpio || start + count >= chip->ngpio)
                        continue;

                bitmap_clear(chip->valid_mask, start, count);
        }
};

#ifdef CONFIG_PINCTRL
static int of_gpiochip_add_pin_range(struct gpio_chip *chip)
{
        struct device_node *np = chip->of_node;
        struct of_phandle_args pinspec;
        struct pinctrl_dev *pctldev;
        int index = 0, ret;
        const char *name;
        static const char group_names_propname[] = "gpio-ranges-group-names";
        struct property *group_names;

        if (!np)
                return 0;

        group_names = of_find_property(np, group_names_propname, NULL);

        for (;; index++) {
                ret = of_parse_phandle_with_fixed_args(np, "gpio-ranges", 3,
                                index, &pinspec);
                if (ret)
                        break;

                pctldev = of_pinctrl_get(pinspec.np);
                of_node_put(pinspec.np);
                if (!pctldev)
                        return -EPROBE_DEFER;

                if (pinspec.args[2]) {
                        if (group_names) {
                                of_property_read_string_index(np,
                                                group_names_propname,
                                                index, &name);
                                if (strlen(name)) {
                                        pr_err("%pOF: Group name of numeric GPIO ranges must be the empty string.\n",
                                                np);
                                        break;
                                }
                        }
                        /* npins != 0: linear range */
                        ret = gpiochip_add_pin_range(chip,
                                        pinctrl_dev_get_devname(pctldev),
                                        pinspec.args[0],
                                        pinspec.args[1],
                                        pinspec.args[2]);
                        if (ret)
                                return ret;
                } else {
                        /* npins == 0: special range */
                        if (pinspec.args[1]) {
                                pr_err("%pOF: Illegal gpio-range format.\n",
                                        np);
                                break;
                        }

                        if (!group_names) {
                                pr_err("%pOF: GPIO group range requested but no %s property.\n",
                                        np, group_names_propname);
                                break;
                        }

                        ret = of_property_read_string_index(np,
                                                group_names_propname,
                                                index, &name);
                        if (ret)
                                break;

                        if (!strlen(name)) {
                                pr_err("%pOF: Group name of GPIO group range cannot be the empty string.\n",
                                np);
                                break;
                        }

                        ret = gpiochip_add_pingroup_range(chip, pctldev,
                                                pinspec.args[0], name);
                        if (ret)
                                return ret;
                }
        }

        return 0;
}

#else
static int of_gpiochip_add_pin_range(struct gpio_chip *chip) { return 0; }
#endif

int of_gpiochip_add(struct gpio_chip *chip)
{
        int ret;

        if (!chip->of_node)
                return 0;

        if (!chip->of_xlate) {
                chip->of_gpio_n_cells = 2;
                chip->of_xlate = of_gpio_simple_xlate;
        }

        if (chip->of_gpio_n_cells > MAX_PHANDLE_ARGS)
                return -EINVAL;

        of_gpiochip_init_valid_mask(chip);

        ret = of_gpiochip_add_pin_range(chip);
        if (ret)
                return ret;

        of_node_get(chip->of_node);

        ret = of_gpiochip_scan_gpios(chip);
        if (ret)
                of_node_put(chip->of_node);

        return ret;
}

void of_gpiochip_remove(struct gpio_chip *chip)
{
        of_node_put(chip->of_node);
}

void of_gpio_dev_init(struct gpio_chip *gc, struct gpio_device *gdev)
{
        /* Set default OF node to parent's one if present */
        if (gc->parent)
                gdev->dev.of_node = gc->parent->of_node;

        /* If the gpiochip has an assigned OF node this takes precedence */
        if (gc->of_node)
                gdev->dev.of_node = gc->of_node;
        else
                gc->of_node = gdev->dev.of_node;
}