/*
 * ACPI helpers for GPIO API
 *
 * Copyright (C) 2012, Intel Corporation
 * Authors: Mathias Nyman <mathias.nyman@linux.intel.com>
 *          Mika Westerberg <mika.westerberg@linux.intel.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/errno.h>
#include <linux/gpio.h>
#include <linux/gpio/consumer.h>
#include <linux/gpio/driver.h>
#include <linux/export.h>
#include <linux/acpi.h>
#include <linux/interrupt.h>
#include <linux/mutex.h>
#include <linux/pinctrl/pinctrl.h>

#include "gpiolib.h"

struct acpi_gpio_event {
        struct list_head node;
        acpi_handle handle;
        unsigned int pin;
        unsigned int irq;
        struct gpio_desc *desc;
};

struct acpi_gpio_connection {
        struct list_head node;
        unsigned int pin;
        struct gpio_desc *desc;
};

struct acpi_gpio_chip {
        /*
         * ACPICA requires that the first field of the context parameter
         * passed to acpi_install_address_space_handler() is large enough
         * to hold struct acpi_connection_info.
         */
        struct acpi_connection_info conn_info;
        struct list_head conns;
        struct mutex conn_lock;
        struct gpio_chip *chip;
        struct list_head events;
};

static int acpi_gpiochip_find(struct gpio_chip *gc, void *data)
{
        if (!gc->parent)
                return false;

        return ACPI_HANDLE(gc->parent) == data;
}

#ifdef CONFIG_PINCTRL
/**
 * acpi_gpiochip_pin_to_gpio_offset() - translates ACPI GPIO to Linux GPIO
 * @chip: GPIO chip
 * @pin: ACPI GPIO pin number from GpioIo/GpioInt resource
 *
 * Function takes ACPI GpioIo/GpioInt pin number as a parameter and
 * translates it to a corresponding offset suitable to be passed to a
 * GPIO controller driver.
 *
 * Typically the returned offset is same as @pin, but if the GPIO
 * controller uses pin controller and the mapping is not contiguous the
 * offset might be different.
 */
static int acpi_gpiochip_pin_to_gpio_offset(struct gpio_device *gdev, int pin)
{
        struct gpio_pin_range *pin_range;

        /* If there are no ranges in this chip, use 1:1 mapping */
        if (list_empty(&gdev->pin_ranges))
                return pin;

        list_for_each_entry(pin_range, &gdev->pin_ranges, node) {
                const struct pinctrl_gpio_range *range = &pin_range->range;
                int i;

                if (range->pins) {
                        for (i = 0; i < range->npins; i++) {
                                if (range->pins[i] == pin)
                                        return range->base + i - gdev->base;
                        }
                } else {
                        if (pin >= range->pin_base &&
                            pin < range->pin_base + range->npins) {
                                unsigned gpio_base;

                                gpio_base = range->base - gdev->base;
                                return gpio_base + pin - range->pin_base;
                        }
                }
        }

        return -EINVAL;
}
#else
static inline int acpi_gpiochip_pin_to_gpio_offset(struct gpio_device *gdev,
                                                   int pin)
{
        return pin;
}
#endif

/**
 * acpi_get_gpiod() - Translate ACPI GPIO pin to GPIO descriptor usable with GPIO API
 * @path:       ACPI GPIO controller full path name, (e.g. "\\_SB.GPO1")
 * @pin:        ACPI GPIO pin number (0-based, controller-relative)
 *
 * Return: GPIO descriptor to use with Linux generic GPIO API, or ERR_PTR
 * error value. Specifically returns %-EPROBE_DEFER if the referenced GPIO
 * controller does not have gpiochip registered at the moment. This is to
 * support probe deferral.
 */
static struct gpio_desc *acpi_get_gpiod(char *path, int pin)
{
        struct gpio_chip *chip;
        acpi_handle handle;
        acpi_status status;
        int offset;

        status = acpi_get_handle(NULL, path, &handle);
        if (ACPI_FAILURE(status))
                return ERR_PTR(-ENODEV);

        chip = gpiochip_find(handle, acpi_gpiochip_find);
        if (!chip)
                return ERR_PTR(-EPROBE_DEFER);

        offset = acpi_gpiochip_pin_to_gpio_offset(chip->gpiodev, pin);
        if (offset < 0)
                return ERR_PTR(offset);

        return gpiochip_get_desc(chip, offset);
}

static irqreturn_t acpi_gpio_irq_handler(int irq, void *data)
{
        struct acpi_gpio_event *event = data;

        acpi_evaluate_object(event->handle, NULL, NULL, NULL);

        return IRQ_HANDLED;
}

static irqreturn_t acpi_gpio_irq_handler_evt(int irq, void *data)
{
        struct acpi_gpio_event *event = data;

        acpi_execute_simple_method(event->handle, NULL, event->pin);

        return IRQ_HANDLED;
}

static void acpi_gpio_chip_dh(acpi_handle handle, void *data)
{
        /* The address of this function is used as a key. */
}

static acpi_status acpi_gpiochip_request_interrupt(struct acpi_resource *ares,
                                                   void *context)
{
        struct acpi_gpio_chip *acpi_gpio = context;
        struct gpio_chip *chip = acpi_gpio->chip;
        struct acpi_resource_gpio *agpio;
        acpi_handle handle, evt_handle;
        struct acpi_gpio_event *event;
        irq_handler_t handler = NULL;
        struct gpio_desc *desc;
        unsigned long irqflags;
        int ret, pin, irq;

        if (ares->type != ACPI_RESOURCE_TYPE_GPIO)
                return AE_OK;

        agpio = &ares->data.gpio;
        if (agpio->connection_type != ACPI_RESOURCE_GPIO_TYPE_INT)
                return AE_OK;

        handle = ACPI_HANDLE(chip->parent);
        pin = agpio->pin_table[0];

        if (pin <= 255) {
                char ev_name[5];
                sprintf(ev_name, "_%c%02X",
                        agpio->triggering == ACPI_EDGE_SENSITIVE ? 'E' : 'L',
                        pin);
                if (ACPI_SUCCESS(acpi_get_handle(handle, ev_name, &evt_handle)))
                        handler = acpi_gpio_irq_handler;
        }
        if (!handler) {
                if (ACPI_SUCCESS(acpi_get_handle(handle, "_EVT", &evt_handle)))
                        handler = acpi_gpio_irq_handler_evt;
        }
        if (!handler)
                return AE_BAD_PARAMETER;

        pin = acpi_gpiochip_pin_to_gpio_offset(chip->gpiodev, pin);
        if (pin < 0)
                return AE_BAD_PARAMETER;

        desc = gpiochip_request_own_desc(chip, pin, "ACPI:Event");
        if (IS_ERR(desc)) {
                dev_err(chip->parent, "Failed to request GPIO\n");
                return AE_ERROR;
        }

        gpiod_direction_input(desc);

        ret = gpiochip_lock_as_irq(chip, pin);
        if (ret) {
                dev_err(chip->parent, "Failed to lock GPIO as interrupt\n");
                goto fail_free_desc;
        }

        irq = gpiod_to_irq(desc);
        if (irq < 0) {
                dev_err(chip->parent, "Failed to translate GPIO to IRQ\n");
                goto fail_unlock_irq;
        }

        irqflags = IRQF_ONESHOT;
        if (agpio->triggering == ACPI_LEVEL_SENSITIVE) {
                if (agpio->polarity == ACPI_ACTIVE_HIGH)
                        irqflags |= IRQF_TRIGGER_HIGH;
                else
                        irqflags |= IRQF_TRIGGER_LOW;
        } else {
                switch (agpio->polarity) {
                case ACPI_ACTIVE_HIGH:
                        irqflags |= IRQF_TRIGGER_RISING;
                        break;
                case ACPI_ACTIVE_LOW:
                        irqflags |= IRQF_TRIGGER_FALLING;
                        break;
                default:
                        irqflags |= IRQF_TRIGGER_RISING |
                                    IRQF_TRIGGER_FALLING;
                        break;
                }
        }

        event = kzalloc(sizeof(*event), GFP_KERNEL);
        if (!event)
                goto fail_unlock_irq;

        event->handle = evt_handle;
        event->irq = irq;
        event->pin = pin;
        event->desc = desc;

        ret = request_threaded_irq(event->irq, NULL, handler, irqflags,
                                   "ACPI:Event", event);
        if (ret) {
                dev_err(chip->parent,
                        "Failed to setup interrupt handler for %d\n",
                        event->irq);
                goto fail_free_event;
        }

        list_add_tail(&event->node, &acpi_gpio->events);
        return AE_OK;

fail_free_event:
        kfree(event);
fail_unlock_irq:
        gpiochip_unlock_as_irq(chip, pin);
fail_free_desc:
        gpiochip_free_own_desc(desc);

        return AE_ERROR;
}

/**
 * acpi_gpiochip_request_interrupts() - Register isr for gpio chip ACPI events
 * @chip:      GPIO chip
 *
 * ACPI5 platforms can use GPIO signaled ACPI events. These GPIO interrupts are
 * handled by ACPI event methods which need to be called from the GPIO
 * chip's interrupt handler. acpi_gpiochip_request_interrupts finds out which
 * gpio pins have acpi event methods and assigns interrupt handlers that calls
 * the acpi event methods for those pins.
 */
void acpi_gpiochip_request_interrupts(struct gpio_chip *chip)
{
        struct acpi_gpio_chip *acpi_gpio;
        acpi_handle handle;
        acpi_status status;

        if (!chip->parent || !chip->to_irq)
                return;

        handle = ACPI_HANDLE(chip->parent);
        if (!handle)
                return;

        status = acpi_get_data(handle, acpi_gpio_chip_dh, (void **)&acpi_gpio);
        if (ACPI_FAILURE(status))
                return;

        acpi_walk_resources(handle, "_AEI",
                            acpi_gpiochip_request_interrupt, acpi_gpio);
}
EXPORT_SYMBOL_GPL(acpi_gpiochip_request_interrupts);

/**
 * acpi_gpiochip_free_interrupts() - Free GPIO ACPI event interrupts.
 * @chip:      GPIO chip
 *
 * Free interrupts associated with GPIO ACPI event method for the given
 * GPIO chip.
 */
void acpi_gpiochip_free_interrupts(struct gpio_chip *chip)
{
        struct acpi_gpio_chip *acpi_gpio;
        struct acpi_gpio_event *event, *ep;
        acpi_handle handle;
        acpi_status status;

        if (!chip->parent || !chip->to_irq)
                return;

        handle = ACPI_HANDLE(chip->parent);
        if (!handle)
                return;

        status = acpi_get_data(handle, acpi_gpio_chip_dh, (void **)&acpi_gpio);
        if (ACPI_FAILURE(status))
                return;

        list_for_each_entry_safe_reverse(event, ep, &acpi_gpio->events, node) {
                struct gpio_desc *desc;

                free_irq(event->irq, event);
                desc = event->desc;
                if (WARN_ON(IS_ERR(desc)))
                        continue;
                gpiochip_unlock_as_irq(chip, event->pin);
                gpiochip_free_own_desc(desc);
                list_del(&event->node);
                kfree(event);
        }
}
EXPORT_SYMBOL_GPL(acpi_gpiochip_free_interrupts);

int acpi_dev_add_driver_gpios(struct acpi_device *adev,
                              const struct acpi_gpio_mapping *gpios)
{
        if (adev && gpios) {
                adev->driver_gpios = gpios;
                return 0;
        }
        return -EINVAL;
}
EXPORT_SYMBOL_GPL(acpi_dev_add_driver_gpios);

static bool acpi_get_driver_gpio_data(struct acpi_device *adev,
                                      const char *name, int index,
                                      struct acpi_reference_args *args)
{
        const struct acpi_gpio_mapping *gm;

        if (!adev->driver_gpios)
                return false;

        for (gm = adev->driver_gpios; gm->name; gm++)
                if (!strcmp(name, gm->name) && gm->data && index < gm->size) {
                        const struct acpi_gpio_params *par = gm->data + index;

                        args->adev = adev;
                        args->args[0] = par->crs_entry_index;
                        args->args[1] = par->line_index;
                        args->args[2] = par->active_low;
                        args->nargs = 3;
                        return true;
                }

        return false;
}

struct acpi_gpio_lookup {
        struct acpi_gpio_info info;
        int index;
        int pin_index;
        bool active_low;
        struct acpi_device *adev;
        struct gpio_desc *desc;
        int n;
};

static int acpi_find_gpio(struct acpi_resource *ares, void *data)
{
        struct acpi_gpio_lookup *lookup = data;

        if (ares->type != ACPI_RESOURCE_TYPE_GPIO)
                return 1;

        if (lookup->n++ == lookup->index && !lookup->desc) {
                const struct acpi_resource_gpio *agpio = &ares->data.gpio;
                int pin_index = lookup->pin_index;

                if (pin_index >= agpio->pin_table_length)
                        return 1;

                lookup->desc = acpi_get_gpiod(agpio->resource_source.string_ptr,
                                              agpio->pin_table[pin_index]);
                lookup->info.gpioint =
                        agpio->connection_type == ACPI_RESOURCE_GPIO_TYPE_INT;

                /*
                 * ActiveLow is only specified for GpioInt resource. If
                 * GpioIo is used then the only way to set the flag is
                 * to use _DSD "gpios" property.
                 * Note: we expect here:
                 * - ACPI_ACTIVE_LOW == GPIO_ACTIVE_LOW
                 * - ACPI_ACTIVE_HIGH == GPIO_ACTIVE_HIGH
                 */
                if (lookup->info.gpioint) {
                        lookup->info.polarity = agpio->polarity;
                        lookup->info.triggering = agpio->triggering;
                }

        }

        return 1;
}

static int acpi_gpio_resource_lookup(struct acpi_gpio_lookup *lookup,
                                     struct acpi_gpio_info *info)
{
        struct list_head res_list;
        int ret;

        INIT_LIST_HEAD(&res_list);

        ret = acpi_dev_get_resources(lookup->adev, &res_list, acpi_find_gpio,
                                     lookup);
        if (ret < 0)
                return ret;

        acpi_dev_free_resource_list(&res_list);

        if (!lookup->desc)
                return -ENOENT;

        if (info) {
                *info = lookup->info;
                if (lookup->active_low)
                        info->polarity = lookup->active_low;
        }
        return 0;
}

static int acpi_gpio_property_lookup(struct fwnode_handle *fwnode,
                                     const char *propname, int index,
                                     struct acpi_gpio_lookup *lookup)
{
        struct acpi_reference_args args;
        int ret;

        memset(&args, 0, sizeof(args));
        ret = acpi_node_get_property_reference(fwnode, propname, index, &args);
        if (ret) {
                struct acpi_device *adev = to_acpi_device_node(fwnode);

                if (!adev)
                        return ret;

                if (!acpi_get_driver_gpio_data(adev, propname, index, &args))
                        return ret;
        }
        /*
         * The property was found and resolved, so need to lookup the GPIO based
         * on returned args.
         */
        lookup->adev = args.adev;
        if (args.nargs >= 2) {
                lookup->index = args.args[0];
                lookup->pin_index = args.args[1];
                /* 3rd argument, if present is used to specify active_low. */
                if (args.nargs >= 3)
                        lookup->active_low = !!args.args[2];
        }
        return 0;
}

/**
 * acpi_get_gpiod_by_index() - get a GPIO descriptor from device resources
 * @adev: pointer to a ACPI device to get GPIO from
 * @propname: Property name of the GPIO (optional)
 * @index: index of GpioIo/GpioInt resource (starting from %0)
 * @info: info pointer to fill in (optional)
 *
 * Function goes through ACPI resources for @adev and based on @index looks
 * up a GpioIo/GpioInt resource, translates it to the Linux GPIO descriptor,
 * and returns it. @index matches GpioIo/GpioInt resources only so if there
 * are total %3 GPIO resources, the index goes from %0 to %2.
 *
 * If @propname is specified the GPIO is looked using device property. In
 * that case @index is used to select the GPIO entry in the property value
 * (in case of multiple).
 *
 * If the GPIO cannot be translated or there is an error an ERR_PTR is
 * returned.
 *
 * Note: if the GPIO resource has multiple entries in the pin list, this
 * function only returns the first.
 */
struct gpio_desc *acpi_get_gpiod_by_index(struct acpi_device *adev,
                                          const char *propname, int index,
                                          struct acpi_gpio_info *info)
{
        struct acpi_gpio_lookup lookup;
        int ret;

        if (!adev)
                return ERR_PTR(-ENODEV);

        memset(&lookup, 0, sizeof(lookup));
        lookup.index = index;

        if (propname) {
                dev_dbg(&adev->dev, "GPIO: looking up %s\n", propname);

                ret = acpi_gpio_property_lookup(acpi_fwnode_handle(adev),
                                                propname, index, &lookup);
                if (ret)
                        return ERR_PTR(ret);

                dev_dbg(&adev->dev, "GPIO: _DSD returned %s %d %d %u\n",
                        dev_name(&lookup.adev->dev), lookup.index,
                        lookup.pin_index, lookup.active_low);
        } else {
                dev_dbg(&adev->dev, "GPIO: looking up %d in _CRS\n", index);
                lookup.adev = adev;
        }

        ret = acpi_gpio_resource_lookup(&lookup, info);
        return ret ? ERR_PTR(ret) : lookup.desc;
}

/**
 * acpi_node_get_gpiod() - get a GPIO descriptor from ACPI resources
 * @fwnode: pointer to an ACPI firmware node to get the GPIO information from
 * @propname: Property name of the GPIO
 * @index: index of GpioIo/GpioInt resource (starting from %0)
 * @info: info pointer to fill in (optional)
 *
 * If @fwnode is an ACPI device object, call %acpi_get_gpiod_by_index() for it.
 * Otherwise (ie. it is a data-only non-device object), use the property-based
 * GPIO lookup to get to the GPIO resource with the relevant information and use
 * that to obtain the GPIO descriptor to return.
 */
struct gpio_desc *acpi_node_get_gpiod(struct fwnode_handle *fwnode,
                                      const char *propname, int index,
                                      struct acpi_gpio_info *info)
{
        struct acpi_gpio_lookup lookup;
        struct acpi_device *adev;
        int ret;

        adev = to_acpi_device_node(fwnode);
        if (adev)
                return acpi_get_gpiod_by_index(adev, propname, index, info);

        if (!is_acpi_data_node(fwnode))
                return ERR_PTR(-ENODEV);

        if (!propname)
                return ERR_PTR(-EINVAL);

        memset(&lookup, 0, sizeof(lookup));
        lookup.index = index;

        ret = acpi_gpio_property_lookup(fwnode, propname, index, &lookup);
        if (ret)
                return ERR_PTR(ret);

        ret = acpi_gpio_resource_lookup(&lookup, info);
        return ret ? ERR_PTR(ret) : lookup.desc;
}

/**
 * acpi_dev_gpio_irq_get() - Find GpioInt and translate it to Linux IRQ number
 * @adev: pointer to a ACPI device to get IRQ from
 * @index: index of GpioInt resource (starting from %0)
 *
 * If the device has one or more GpioInt resources, this function can be
 * used to translate from the GPIO offset in the resource to the Linux IRQ
 * number.
 *
 * Return: Linux IRQ number (>%0) on success, negative errno on failure.
 */
int acpi_dev_gpio_irq_get(struct acpi_device *adev, int index)
{
        int idx, i;
        unsigned int irq_flags;

        for (i = 0, idx = 0; idx <= index; i++) {
                struct acpi_gpio_info info;
                struct gpio_desc *desc;

                desc = acpi_get_gpiod_by_index(adev, NULL, i, &info);
                if (IS_ERR(desc))
                        break;
                if (info.gpioint && idx++ == index) {
                        int irq = gpiod_to_irq(desc);

                        if (irq < 0)
                                return irq;

                        irq_flags = acpi_dev_get_irq_type(info.triggering,
                                                          info.polarity);

                        /* Set type if specified and different than the current one */
                        if (irq_flags != IRQ_TYPE_NONE &&
                            irq_flags != irq_get_trigger_type(irq))
                                irq_set_irq_type(irq, irq_flags);

                        return irq;
                }

        }
        return -ENOENT;
}
EXPORT_SYMBOL_GPL(acpi_dev_gpio_irq_get);

static acpi_status
acpi_gpio_adr_space_handler(u32 function, acpi_physical_address address,
                            u32 bits, u64 *value, void *handler_context,
                            void *region_context)
{
        struct acpi_gpio_chip *achip = region_context;
        struct gpio_chip *chip = achip->chip;
        struct acpi_resource_gpio *agpio;
        struct acpi_resource *ares;
        int pin_index = (int)address;
        acpi_status status;
        bool pull_up;
        int length;
        int i;

        status = acpi_buffer_to_resource(achip->conn_info.connection,
                                         achip->conn_info.length, &ares);
        if (ACPI_FAILURE(status))
                return status;

        if (WARN_ON(ares->type != ACPI_RESOURCE_TYPE_GPIO)) {
                ACPI_FREE(ares);
                return AE_BAD_PARAMETER;
        }

        agpio = &ares->data.gpio;
        pull_up = agpio->pin_config == ACPI_PIN_CONFIG_PULLUP;

        if (WARN_ON(agpio->io_restriction == ACPI_IO_RESTRICT_INPUT &&
            function == ACPI_WRITE)) {
                ACPI_FREE(ares);
                return AE_BAD_PARAMETER;
        }

        length = min(agpio->pin_table_length, (u16)(pin_index + bits));
        for (i = pin_index; i < length; ++i) {
                int pin = agpio->pin_table[i];
                struct acpi_gpio_connection *conn;
                struct gpio_desc *desc;
                bool found;

                pin = acpi_gpiochip_pin_to_gpio_offset(chip->gpiodev, pin);
                if (pin < 0) {
                        status = AE_BAD_PARAMETER;
                        goto out;
                }

                mutex_lock(&achip->conn_lock);

                found = false;
                list_for_each_entry(conn, &achip->conns, node) {
                        if (conn->pin == pin) {
                                found = true;
                                desc = conn->desc;
                                break;
                        }
                }

                /*
                 * The same GPIO can be shared between operation region and
                 * event but only if the access here is ACPI_READ. In that
                 * case we "borrow" the event GPIO instead.
                 */
                if (!found && agpio->sharable == ACPI_SHARED &&
                     function == ACPI_READ) {
                        struct acpi_gpio_event *event;

                        list_for_each_entry(event, &achip->events, node) {
                                if (event->pin == pin) {
                                        desc = event->desc;
                                        found = true;
                                        break;
                                }
                        }
                }

                if (!found) {
                        desc = gpiochip_request_own_desc(chip, pin,
                                                         "ACPI:OpRegion");
                        if (IS_ERR(desc)) {
                                status = AE_ERROR;
                                mutex_unlock(&achip->conn_lock);
                                goto out;
                        }

                        switch (agpio->io_restriction) {
                        case ACPI_IO_RESTRICT_INPUT:
                                gpiod_direction_input(desc);
                                break;
                        case ACPI_IO_RESTRICT_OUTPUT:
                                /*
                                 * ACPI GPIO resources don't contain an
                                 * initial value for the GPIO. Therefore we
                                 * deduce that value from the pull field
                                 * instead. If the pin is pulled up we
                                 * assume default to be high, otherwise
                                 * low.
                                 */
                                gpiod_direction_output(desc, pull_up);
                                break;
                        default:
                                /*
                                 * Assume that the BIOS has configured the
                                 * direction and pull accordingly.
                                 */
                                break;
                        }

                        conn = kzalloc(sizeof(*conn), GFP_KERNEL);
                        if (!conn) {
                                status = AE_NO_MEMORY;
                                gpiochip_free_own_desc(desc);
                                mutex_unlock(&achip->conn_lock);
                                goto out;
                        }

                        conn->pin = pin;
                        conn->desc = desc;
                        list_add_tail(&conn->node, &achip->conns);
                }

                mutex_unlock(&achip->conn_lock);

                if (function == ACPI_WRITE)
                        gpiod_set_raw_value_cansleep(desc,
                                                     !!((1 << i) & *value));
                else
                        *value |= (u64)gpiod_get_raw_value_cansleep(desc) << i;
        }

out:
        ACPI_FREE(ares);
        return status;
}

static void acpi_gpiochip_request_regions(struct acpi_gpio_chip *achip)
{
        struct gpio_chip *chip = achip->chip;
        acpi_handle handle = ACPI_HANDLE(chip->parent);
        acpi_status status;

        INIT_LIST_HEAD(&achip->conns);
        mutex_init(&achip->conn_lock);
        status = acpi_install_address_space_handler(handle, ACPI_ADR_SPACE_GPIO,
                                                    acpi_gpio_adr_space_handler,
                                                    NULL, achip);
        if (ACPI_FAILURE(status))
                dev_err(chip->parent,
                        "Failed to install GPIO OpRegion handler\n");
}

static void acpi_gpiochip_free_regions(struct acpi_gpio_chip *achip)
{
        struct gpio_chip *chip = achip->chip;
        acpi_handle handle = ACPI_HANDLE(chip->parent);
        struct acpi_gpio_connection *conn, *tmp;
        acpi_status status;

        status = acpi_remove_address_space_handler(handle, ACPI_ADR_SPACE_GPIO,
                                                   acpi_gpio_adr_space_handler);
        if (ACPI_FAILURE(status)) {
                dev_err(chip->parent,
                        "Failed to remove GPIO OpRegion handler\n");
                return;
        }

        list_for_each_entry_safe_reverse(conn, tmp, &achip->conns, node) {
                gpiochip_free_own_desc(conn->desc);
                list_del(&conn->node);
                kfree(conn);
        }
}

void acpi_gpiochip_add(struct gpio_chip *chip)
{
        struct acpi_gpio_chip *acpi_gpio;
        acpi_handle handle;
        acpi_status status;

        if (!chip || !chip->parent)
                return;

        handle = ACPI_HANDLE(chip->parent);
        if (!handle)
                return;

        acpi_gpio = kzalloc(sizeof(*acpi_gpio), GFP_KERNEL);
        if (!acpi_gpio) {
                dev_err(chip->parent,
                        "Failed to allocate memory for ACPI GPIO chip\n");
                return;
        }

        acpi_gpio->chip = chip;
        INIT_LIST_HEAD(&acpi_gpio->events);

        status = acpi_attach_data(handle, acpi_gpio_chip_dh, acpi_gpio);
        if (ACPI_FAILURE(status)) {
                dev_err(chip->parent, "Failed to attach ACPI GPIO chip\n");
                kfree(acpi_gpio);
                return;
        }

        acpi_gpiochip_request_regions(acpi_gpio);
}

void acpi_gpiochip_remove(struct gpio_chip *chip)
{
        struct acpi_gpio_chip *acpi_gpio;
        acpi_handle handle;
        acpi_status status;

        if (!chip || !chip->parent)
                return;

        handle = ACPI_HANDLE(chip->parent);
        if (!handle)
                return;

        status = acpi_get_data(handle, acpi_gpio_chip_dh, (void **)&acpi_gpio);
        if (ACPI_FAILURE(status)) {
                dev_warn(chip->parent, "Failed to retrieve ACPI GPIO chip\n");
                return;
        }

        acpi_gpiochip_free_regions(acpi_gpio);

        acpi_detach_data(handle, acpi_gpio_chip_dh);
        kfree(acpi_gpio);
}

static unsigned int acpi_gpio_package_count(const union acpi_object *obj)
{
        const union acpi_object *element = obj->package.elements;
        const union acpi_object *end = element + obj->package.count;
        unsigned int count = 0;

        while (element < end) {
                if (element->type == ACPI_TYPE_LOCAL_REFERENCE)
                        count++;

                element++;
        }
        return count;
}

static int acpi_find_gpio_count(struct acpi_resource *ares, void *data)
{
        unsigned int *count = data;

        if (ares->type == ACPI_RESOURCE_TYPE_GPIO)
                *count += ares->data.gpio.pin_table_length;

        return 1;
}

/**
 * acpi_gpio_count - return the number of GPIOs associated with a
 *              device / function or -ENOENT if no GPIO has been
 *              assigned to the requested function.
 * @dev:        GPIO consumer, can be NULL for system-global GPIOs
 * @con_id:     function within the GPIO consumer
 */
int acpi_gpio_count(struct device *dev, const char *con_id)
{
        struct acpi_device *adev = ACPI_COMPANION(dev);
        const union acpi_object *obj;
        const struct acpi_gpio_mapping *gm;
        int count = -ENOENT;
        int ret;
        char propname[32];
        unsigned int i;

        /* Try first from _DSD */
        for (i = 0; i < ARRAY_SIZE(gpio_suffixes); i++) {
                if (con_id && strcmp(con_id, "gpios"))
                        snprintf(propname, sizeof(propname), "%s-%s",
                                 con_id, gpio_suffixes[i]);
                else
                        snprintf(propname, sizeof(propname), "%s",
                                 gpio_suffixes[i]);

                ret = acpi_dev_get_property(adev, propname, ACPI_TYPE_ANY,
                                            &obj);
                if (ret == 0) {
                        if (obj->type == ACPI_TYPE_LOCAL_REFERENCE)
                                count = 1;
                        else if (obj->type == ACPI_TYPE_PACKAGE)
                                count = acpi_gpio_package_count(obj);
                } else if (adev->driver_gpios) {
                        for (gm = adev->driver_gpios; gm->name; gm++)
                                if (strcmp(propname, gm->name) == 0) {
                                        count = gm->size;
                                        break;
                                }
                }
                if (count >= 0)
                        break;
        }

        /* Then from plain _CRS GPIOs */
        if (count < 0) {
                struct list_head resource_list;
                unsigned int crs_count = 0;

                INIT_LIST_HEAD(&resource_list);
                acpi_dev_get_resources(adev, &resource_list,
                                       acpi_find_gpio_count, &crs_count);
                acpi_dev_free_resource_list(&resource_list);
                if (crs_count > 0)
                        count = crs_count;
        }
        return count;
}

struct acpi_crs_lookup {
        struct list_head node;
        struct acpi_device *adev;
        const char *con_id;
};

static DEFINE_MUTEX(acpi_crs_lookup_lock);
static LIST_HEAD(acpi_crs_lookup_list);

bool acpi_can_fallback_to_crs(struct acpi_device *adev, const char *con_id)
{
        struct acpi_crs_lookup *l, *lookup = NULL;

        /* Never allow fallback if the device has properties */
        if (adev->data.properties || adev->driver_gpios)
                return false;

        mutex_lock(&acpi_crs_lookup_lock);

        list_for_each_entry(l, &acpi_crs_lookup_list, node) {
                if (l->adev == adev) {
                        lookup = l;
                        break;
                }
        }

        if (!lookup) {
                lookup = kmalloc(sizeof(*lookup), GFP_KERNEL);
                if (lookup) {
                        lookup->adev = adev;
                        lookup->con_id = kstrdup(con_id, GFP_KERNEL);
                        list_add_tail(&lookup->node, &acpi_crs_lookup_list);
                }
        }

        mutex_unlock(&acpi_crs_lookup_lock);

        return lookup &&
                ((!lookup->con_id && !con_id) ||
                 (lookup->con_id && con_id &&
                  strcmp(lookup->con_id, con_id) == 0));
}