/*
 * 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/consumer.h>
#include <linux/gpio/driver.h>
#include <linux/export.h>
#include <linux/acpi.h>
#include <linux/interrupt.h>

#include "gpiolib.h"

struct acpi_gpio_evt_pin {
        struct list_head node;
        acpi_handle *evt_handle;
        unsigned int pin;
        unsigned int irq;
};

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

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

/**
 * 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;

        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);

        if (pin < 0 || pin > chip->ngpio)
                return ERR_PTR(-EINVAL);

        return gpio_to_desc(chip->base + pin);
}

static irqreturn_t acpi_gpio_irq_handler(int irq, void *data)
{
        acpi_handle handle = data;

        acpi_evaluate_object(handle, NULL, NULL, NULL);

        return IRQ_HANDLED;
}

static irqreturn_t acpi_gpio_irq_handler_evt(int irq, void *data)
{
        struct acpi_gpio_evt_pin *evt_pin = data;

        acpi_execute_simple_method(evt_pin->evt_handle, NULL, evt_pin->pin);

        return IRQ_HANDLED;
}

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

/**
 * 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.
 */
static void acpi_gpiochip_request_interrupts(struct gpio_chip *chip)
{
        struct acpi_buffer buf = {ACPI_ALLOCATE_BUFFER, NULL};
        struct acpi_resource *res;
        acpi_handle handle, evt_handle;
        struct list_head *evt_pins = NULL;
        acpi_status status;
        unsigned int pin;
        int irq, ret;
        char ev_name[5];

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

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

        status = acpi_get_event_resources(handle, &buf);
        if (ACPI_FAILURE(status))
                return;

        status = acpi_get_handle(handle, "_EVT", &evt_handle);
        if (ACPI_SUCCESS(status)) {
                evt_pins = kzalloc(sizeof(*evt_pins), GFP_KERNEL);
                if (evt_pins) {
                        INIT_LIST_HEAD(evt_pins);
                        status = acpi_attach_data(handle, acpi_gpio_evt_dh,
                                                  evt_pins);
                        if (ACPI_FAILURE(status)) {
                                kfree(evt_pins);
                                evt_pins = NULL;
                        }
                }
        }

        /*
         * If a GPIO interrupt has an ACPI event handler method, or _EVT is
         * present, set up an interrupt handler that calls the ACPI event
         * handler.
         */
        for (res = buf.pointer;
             res && (res->type != ACPI_RESOURCE_TYPE_END_TAG);
             res = ACPI_NEXT_RESOURCE(res)) {
                irq_handler_t handler = NULL;
                void *data;

                if (res->type != ACPI_RESOURCE_TYPE_GPIO ||
                    res->data.gpio.connection_type !=
                    ACPI_RESOURCE_GPIO_TYPE_INT)
                        continue;

                pin = res->data.gpio.pin_table[0];
                if (pin > chip->ngpio)
                        continue;

                irq = chip->to_irq(chip, pin);
                if (irq < 0)
                        continue;

                if (pin <= 255) {
                        acpi_handle ev_handle;

                        sprintf(ev_name, "_%c%02X",
                                res->data.gpio.triggering ? 'E' : 'L', pin);
                        status = acpi_get_handle(handle, ev_name, &ev_handle);
                        if (ACPI_SUCCESS(status)) {
                                handler = acpi_gpio_irq_handler;
                                data = ev_handle;
                        }
                }
                if (!handler && evt_pins) {
                        struct acpi_gpio_evt_pin *evt_pin;

                        evt_pin = kzalloc(sizeof(*evt_pin), GFP_KERNEL);
                        if (!evt_pin)
                                continue;

                        list_add_tail(&evt_pin->node, evt_pins);
                        evt_pin->evt_handle = evt_handle;
                        evt_pin->pin = pin;
                        evt_pin->irq = irq;
                        handler = acpi_gpio_irq_handler_evt;
                        data = evt_pin;
                }
                if (!handler)
                        continue;

                /* Assume BIOS sets the triggering, so no flags */
                ret = devm_request_threaded_irq(chip->dev, irq, NULL, handler,
                                                0, "GPIO-signaled-ACPI-event",
                                                data);
                if (ret)
                        dev_err(chip->dev,
                                "Failed to request IRQ %d ACPI event handler\n",
                                irq);
        }
}

/**
 * acpi_gpiochip_free_interrupts() - Free GPIO _EVT ACPI event interrupts.
 * @chip:      gpio chip
 *
 * Free interrupts associated with the _EVT method for the given GPIO chip.
 *
 * The remaining ACPI event interrupts associated with the chip are freed
 * automatically.
 */
static void acpi_gpiochip_free_interrupts(struct gpio_chip *chip)
{
        acpi_handle handle;
        acpi_status status;
        struct list_head *evt_pins;
        struct acpi_gpio_evt_pin *evt_pin, *ep;

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

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

        status = acpi_get_data(handle, acpi_gpio_evt_dh, (void **)&evt_pins);
        if (ACPI_FAILURE(status))
                return;

        list_for_each_entry_safe_reverse(evt_pin, ep, evt_pins, node) {
                devm_free_irq(chip->dev, evt_pin->irq, evt_pin);
                list_del(&evt_pin->node);
                kfree(evt_pin);
        }

        acpi_detach_data(handle, acpi_gpio_evt_dh);
        kfree(evt_pins);
}

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 void devm_acpi_dev_release_driver_gpios(struct device *dev, void *res)
{
        acpi_dev_remove_driver_gpios(ACPI_COMPANION(dev));
}

int devm_acpi_dev_add_driver_gpios(struct device *dev,
                                   const struct acpi_gpio_mapping *gpios)
{
        void *res;
        int ret;

        res = devres_alloc(devm_acpi_dev_release_driver_gpios, 0, GFP_KERNEL);
        if (!res)
                return -ENOMEM;

        ret = acpi_dev_add_driver_gpios(ACPI_COMPANION(dev), gpios);
        if (ret) {
                devres_free(res);
                return ret;
        }
        devres_add(dev, res);
        return 0;
}
EXPORT_SYMBOL_GPL(devm_acpi_dev_add_driver_gpios);

void devm_acpi_dev_remove_driver_gpios(struct device *dev)
{
        WARN_ON(devres_release(dev, devm_acpi_dev_release_driver_gpios, NULL, NULL));
}
EXPORT_SYMBOL_GPL(devm_acpi_dev_remove_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_node_get_property_reference(acpi_fwnode_handle(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);
}

/**
 * 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;

        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)
                        return gpiod_to_irq(desc);
        }
        return -ENOENT;
}
EXPORT_SYMBOL_GPL(acpi_dev_gpio_irq_get);

void acpi_gpiochip_add(struct gpio_chip *chip)
{
        acpi_gpiochip_request_interrupts(chip);
}

void acpi_gpiochip_remove(struct gpio_chip *chip)
{
        acpi_gpiochip_free_interrupts(chip);
}