/*
 * 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/export.h>
#include <linux/acpi_gpio.h>
#include <linux/acpi.h>
#include <linux/interrupt.h>

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

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

/**
 * acpi_get_gpio() - Translate ACPI GPIO pin to GPIO number 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 number to use with Linux generic GPIO API, or errno error value
 */

int acpi_get_gpio(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 -ENODEV;

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

	if (!gpio_is_valid(chip->base + pin))
		return -EINVAL;

	return chip->base + pin;
}
EXPORT_SYMBOL_GPL(acpi_get_gpio);


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;
}

/**
 * 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.
 *
 * Interrupts are automatically freed on driver detach
 */

void acpi_gpiochip_request_interrupts(struct gpio_chip *chip)
{
	struct acpi_buffer buf = {ACPI_ALLOCATE_BUFFER, NULL};
	struct acpi_resource *res;
	acpi_handle handle, ev_handle;
	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;

	/* If a gpio interrupt has an acpi event handler method, then
	 * 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)) {

		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;

		sprintf(ev_name, "_%c%02X",
		res->data.gpio.triggering ? 'E' : 'L', pin);

		status = acpi_get_handle(handle, ev_name, &ev_handle);
		if (ACPI_FAILURE(status))
			continue;

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

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