include/linux/apple-gmux.h

/* SPDX-License-Identifier: GPL-2.0-only */
/*
 * apple-gmux.h - microcontroller built into dual GPU MacBook Pro & Mac Pro
 * Copyright (C) 2015 Lukas Wunner <lukas@wunner.de>
 */

#ifndef LINUX_APPLE_GMUX_H
#define LINUX_APPLE_GMUX_H

#include <linux/acpi.h>
#include <linux/io.h>
#include <linux/pnp.h>

#define GMUX_ACPI_HID "APP000B"

/*
 * gmux port offsets. Many of these are not yet used, but may be in the
 * future, and it's useful to have them documented here anyhow.
 */
#define GMUX_PORT_VERSION_MAJOR		0x04
#define GMUX_PORT_VERSION_MINOR		0x05
#define GMUX_PORT_VERSION_RELEASE	0x06
#define GMUX_PORT_SWITCH_DISPLAY	0x10
#define GMUX_PORT_SWITCH_GET_DISPLAY	0x11
#define GMUX_PORT_INTERRUPT_ENABLE	0x14
#define GMUX_PORT_INTERRUPT_STATUS	0x16
#define GMUX_PORT_SWITCH_DDC		0x28
#define GMUX_PORT_SWITCH_EXTERNAL	0x40
#define GMUX_PORT_SWITCH_GET_EXTERNAL	0x41
#define GMUX_PORT_DISCRETE_POWER	0x50
#define GMUX_PORT_MAX_BRIGHTNESS	0x70
#define GMUX_PORT_BRIGHTNESS		0x74
#define GMUX_PORT_VALUE			0xc2
#define GMUX_PORT_READ			0xd0
#define GMUX_PORT_WRITE			0xd4

#define GMUX_MIN_IO_LEN			(GMUX_PORT_BRIGHTNESS + 4)

#if IS_ENABLED(CONFIG_APPLE_GMUX)
static inline bool apple_gmux_is_indexed(unsigned long iostart)
{
	u16 val;

	outb(0xaa, iostart + 0xcc);
	outb(0x55, iostart + 0xcd);
	outb(0x00, iostart + 0xce);

	val = inb(iostart + 0xcc) | (inb(iostart + 0xcd) << 8);
	if (val == 0x55aa)
		return true;

	return false;
}

/**
 * apple_gmux_detect() - detect if gmux is built into the machine
 *
 * @pnp_dev:     Device to probe or NULL to use the first matching device
 * @indexed_ret: Returns (by reference) if the gmux is indexed or not
 *
 * Detect if a supported gmux device is present by actually probing it.
 * This avoids the false positives returned on some models by
 * apple_gmux_present().
 *
 * Return: %true if a supported gmux ACPI device is detected and the kernel
 * was configured with CONFIG_APPLE_GMUX, %false otherwise.
 */
static inline bool apple_gmux_detect(struct pnp_dev *pnp_dev, bool *indexed_ret)
{
	u8 ver_major, ver_minor, ver_release;
	struct device *dev = NULL;
	struct acpi_device *adev;
	struct resource *res;
	bool indexed = false;
	bool ret = false;

	if (!pnp_dev) {
		adev = acpi_dev_get_first_match_dev(GMUX_ACPI_HID, NULL, -1);
		if (!adev)
			return false;

		dev = get_device(acpi_get_first_physical_node(adev));
		acpi_dev_put(adev);
		if (!dev)
			return false;

		pnp_dev = to_pnp_dev(dev);
	}

	res = pnp_get_resource(pnp_dev, IORESOURCE_IO, 0);
	if (!res || resource_size(res) < GMUX_MIN_IO_LEN)
		goto out;

	/*
	 * Invalid version information may indicate either that the gmux
	 * device isn't present or that it's a new one that uses indexed io.
	 */
	ver_major = inb(res->start + GMUX_PORT_VERSION_MAJOR);
	ver_minor = inb(res->start + GMUX_PORT_VERSION_MINOR);
	ver_release = inb(res->start + GMUX_PORT_VERSION_RELEASE);
	if (ver_major == 0xff && ver_minor == 0xff && ver_release == 0xff) {
		indexed = apple_gmux_is_indexed(res->start);
		if (!indexed)
			goto out;
	}

	if (indexed_ret)
		*indexed_ret = indexed;

	ret = true;
out:
	put_device(dev);
	return ret;
}

/**
 * apple_gmux_present() - check if gmux ACPI device is present
 *
 * Drivers may use this to activate quirks specific to dual GPU MacBook Pros
 * and Mac Pros, e.g. for deferred probing, runtime pm and backlight.
 *
 * Return: %true if gmux ACPI device is present and the kernel was configured
 * with CONFIG_APPLE_GMUX, %false otherwise.
 */
static inline bool apple_gmux_present(void)
{
	return acpi_dev_found(GMUX_ACPI_HID);
}

#else  /* !CONFIG_APPLE_GMUX */

static inline bool apple_gmux_present(void)
{
	return false;
}

static inline bool apple_gmux_detect(struct pnp_dev *pnp_dev, bool *indexed_ret)
{
	return false;
}

#endif /* !CONFIG_APPLE_GMUX */

#endif /* LINUX_APPLE_GMUX_H */