/*
 * 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->dev)
                return false;

        return ACPI_HANDLE(gc->dev) == 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 contigous the
 * offset might be different.
 */
static int acpi_gpiochip_pin_to_gpio_offset(struct gpio_chip *chip, int pin)
{
        struct gpio_pin_range *pin_range;

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

        list_for_each_entry(pin_range, &chip->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 - chip->base;
                        }
                } else {
                        if (pin >= range->pin_base &&
                            pin < range->pin_base + range->npins) {
                                unsigned gpio_base;

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

        return -EINVAL;
}
#else
static inline int acpi_gpiochip_pin_to_gpio_offset(struct gpio_chip *chip,
                                                   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)
 *
 * Returns GPIO descriptor to use with Linux generic GPIO API, or ERR_PTR
 * error value
 */

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(-ENODEV);

        offset = acpi_gpiochip_pin_to_gpio_offset(chip, 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->dev);
        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;

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

        gpiod_direction_input(desc);

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

        irq = gpiod_to_irq(desc);
        if (irq < 0) {
                dev_err(chip->dev, "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->dev, "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->dev || !chip->to_irq)
                return;

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

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

        INIT_LIST_HEAD(&acpi_gpio->events);
        acpi_walk_resources(ACPI_HANDLE(chip->dev), "_AEI",
                            acpi_gpiochip_request_interrupt, acpi_gpio);
}

/**
 * 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->dev || !chip->to_irq)
                return;

        handle = ACPI_HANDLE(chip->dev);
        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);
        }
}

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;
        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.
                 */
                if (lookup->info.gpioint)
                        lookup->info.active_low =
                                agpio->polarity == ACPI_ACTIVE_LOW;
        }

        return 1;
}

/**
 * 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;
        struct list_head resource_list;
        bool active_low = false;
        int ret;

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

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

        if (propname) {
                struct acpi_reference_args args;

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

                memset(&args, 0, sizeof(args));
                ret = acpi_dev_get_property_reference(adev, propname,
                                                      index, &args);
                if (ret) {
                        bool found = acpi_get_driver_gpio_data(adev, propname,
                                                               index, &args);
                        if (!found)
                                return ERR_PTR(ret);
                }

                /*
                 * The property was found and resolved so need to
                 * lookup the GPIO based on returned args instead.
                 */
                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)
                                active_low = !!args.args[2];
                }

                dev_dbg(&adev->dev, "GPIO: _DSD returned %s %zd %llu %llu %llu\n",
                        dev_name(&adev->dev), args.nargs,
                        args.args[0], args.args[1], args.args[2]);
        } else {
                dev_dbg(&adev->dev, "GPIO: looking up %d in _CRS\n", index);
        }

        INIT_LIST_HEAD(&resource_list);
        ret = acpi_dev_get_resources(adev, &resource_list, acpi_find_gpio,
                                     &lookup);
        if (ret < 0)
                return ERR_PTR(ret);

        acpi_dev_free_resource_list(&resource_list);

        if (lookup.desc && info) {
                *info = lookup.info;
                if (active_low)
                        info->active_low = active_low;
        }

        return lookup.desc ? lookup.desc : ERR_PTR(-ENOENT);
}

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) {
                unsigned pin = agpio->pin_table[i];
                struct acpi_gpio_connection *conn;
                struct gpio_desc *desc;
                bool found;

                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;
                        }
                }
                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->dev);
        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->dev, "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->dev);
        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->dev, "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->dev)
                return;

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

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

        acpi_gpio->chip = chip;

        status = acpi_attach_data(handle, acpi_gpio_chip_dh, acpi_gpio);
        if (ACPI_FAILURE(status)) {
                dev_err(chip->dev, "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->dev)
                return;

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

        status = acpi_get_data(handle, acpi_gpio_chip_dh, (void **)&acpi_gpio);
        if (ACPI_FAILURE(status)) {
                dev_warn(chip->dev, "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);
}