kernel: Use NULL for pointers in DRIVER_MODULE().

[dragonfly.git] / sys / gnu / dev / misc / apple_gmux / apple-gmux.c

/*
 * apple_gmux - Gmux driver for DragonFly
 *
 * Adapted from linux v4.8: drivers/platform/x86/apple-gmux.c
 *
 */

/*
 *  Gmux driver for Apple laptops
 *
 *  Copyright (C) Canonical Ltd. <seth.forshee@canonical.com>
 *  Copyright (C) 2010-2012 Andreas Heider <andreas@meetr.de>
 *  Copyright (C) 2015 Lukas Wunner <lukas@wunner.de>
 *
 *  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 <sys/param.h>
#include <sys/kernel.h>
#include <sys/bio.h>
#include <sys/bus.h>
#include <sys/malloc.h>
#include <sys/module.h>
#include <sys/proc.h>
#include <sys/types.h>
#include <sys/systm.h>
#include <sys/device.h>
#include <sys/conf.h>
#include <sys/rman.h>

#define pr_fmt(fmt) "apple_gmux: " fmt

#include <linux/types.h>
#include <linux/pci.h>
#include <linux/pci_ids.h>
#include <linux/backlight.h>
#include <linux/apple-gmux.h>
#include <linux/delay.h>
#include <linux/completion.h>

#include <drm/drmP.h>
#ifndef VGA_SWITCHEROO
#define VGA_SWITCHEROO  1       /* Must be always defined */
#endif
#include <linux/vga_switcheroo.h>

#include <bus/pci/pcireg.h>
#include <bus/pci/pcivar.h>
#include "opt_acpi.h"
#include <contrib/dev/acpica/source/include/acpi.h>
#include <contrib/dev/acpica/source/include/accommon.h>
#include <dev/acpica/acpivar.h>

/*
 * 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)

#define GMUX_INTERRUPT_ENABLE           0xff
#define GMUX_INTERRUPT_DISABLE          0x00

#define GMUX_INTERRUPT_STATUS_ACTIVE    0
#define GMUX_INTERRUPT_STATUS_DISPLAY   (1 << 0)
#define GMUX_INTERRUPT_STATUS_POWER     (1 << 2)
#define GMUX_INTERRUPT_STATUS_HOTPLUG   (1 << 3)

#define GMUX_BRIGHTNESS_MASK            0x00ffffff
#define GMUX_MAX_BRIGHTNESS             GMUX_BRIGHTNESS_MASK

/**
 * DOC: Overview
 *
 * :1:  http://www.latticesemi.com/en/Products/FPGAandCPLD/LatticeXP2.aspx
 * :2:  http://www.renesas.com/products/mpumcu/h8s/h8s2100/h8s2113/index.jsp
 *
 * gmux is a microcontroller built into the MacBook Pro to support dual GPUs:
 * A {1}[Lattice XP2] on pre-retinas, a {2}[Renesas R4F2113] on retinas.
 *
 * (The MacPro6,1 2013 also has a gmux, however it is unclear why since it has
 * dual GPUs but no built-in display.)
 *
 * gmux is connected to the LPC bus of the southbridge. Its I/O ports are
 * accessed differently depending on the microcontroller: Driver functions
 * to access a pre-retina gmux are infixed `_pio_`, those for a retina gmux
 * are infixed `_index_`.
 */

struct apple_gmux_softc {
        device_t gmux_dev;
        int io_rid;
        struct resource *io_res;
        bool indexed;
        struct lock lk;

        int unit;

        struct pci_dev *pdev;
        /* struct backlight_device *bdev; */

        /* switcheroo data */
        ACPI_HANDLE dhandle;
        int gpe;
        enum vga_switcheroo_client_id switch_state_display;
        enum vga_switcheroo_client_id switch_state_ddc;
        enum vga_switcheroo_client_id switch_state_external;
        enum vga_switcheroo_state power_state;
        struct completion powerchange_done;
};

static struct apple_gmux_softc *apple_gmux_softc_data;

static void             apple_gmux_lock(struct apple_gmux_softc *sc);
static void             apple_gmux_unlock(struct apple_gmux_softc *sc);
static u8               gmux_pio_read8(struct apple_gmux_softc *sc, uint8_t offset);
static void             gmux_pio_write8(struct apple_gmux_softc *sc, int offset, uint8_t value);
static u32              gmux_pio_read32(struct apple_gmux_softc *sc, uint8_t offset);
//static void           gmux_pio_write32(struct apple_gmux_softc *sc, uint8_t offset, uint32_t value);
static int              gmux_index_wait_ready(struct apple_gmux_softc *sc);
static int              gmux_index_wait_complete(struct apple_gmux_softc *sc);
static u8               gmux_index_read8(struct apple_gmux_softc *sc, uint8_t offset);
static void             gmux_index_write8(struct apple_gmux_softc *sc, int offset, uint8_t value);
static u32              gmux_index_read32(struct apple_gmux_softc *sc, uint8_t offset);
//static void           gmux_index_write32(struct apple_gmux_softc *sc, int offset, uint32_t value);
static u8               gmux_read8(struct apple_gmux_softc *sc, int offset);
static void             gmux_write8(struct apple_gmux_softc *sc, int offset, uint8_t value);
static u32              gmux_read32(struct apple_gmux_softc *sc, int offset);
//static void           gmux_write32(struct apple_gmux_softc *sc, int offset, uint32_t value);
static bool             gmux_is_indexed(struct apple_gmux_softc *sc);
static void             gmux_read_switch_state(struct apple_gmux_softc *sc);
static void             gmux_write_switch_state(struct apple_gmux_softc *sc);
static int              gmux_switchto(enum vga_switcheroo_client_id id);
static int              gmux_switch_ddc(enum vga_switcheroo_client_id id);
static int              gmux_set_discrete_state(struct apple_gmux_softc *sc, enum vga_switcheroo_state state);
static int              gmux_set_power_state(enum vga_switcheroo_client_id id, enum vga_switcheroo_state state);
static inline void      gmux_disable_interrupts(struct apple_gmux_softc *sc);
static inline void      gmux_enable_interrupts(struct apple_gmux_softc *sc);
static inline u8        gmux_interrupt_get_status(struct apple_gmux_softc *sc);
static void             gmux_clear_interrupts(struct apple_gmux_softc *sc);
static void             gmux_notify_handler(ACPI_HANDLE device, UINT32 value, void *context);
static int              apple_gmux_suspend(device_t dev);
static int              apple_gmux_resume(device_t dev);
device_t                gmux_get_io_pdev(void);
static int              apple_gmux_probe(device_t dev);
static int              apple_gmux_attach(device_t dev);
static int              apple_gmux_detach(device_t dev);

static void
apple_gmux_lock(struct apple_gmux_softc *sc)
{
        lockmgr(&sc->lk, LK_EXCLUSIVE);
}

static void
apple_gmux_unlock(struct apple_gmux_softc *sc)
{
        lockmgr(&sc->lk, LK_RELEASE);
}

static u8
gmux_pio_read8(struct apple_gmux_softc *sc, uint8_t offset)
{
        return(bus_read_1(sc->io_res, offset));
}

static void
gmux_pio_write8(struct apple_gmux_softc *sc, int offset, uint8_t value)
{
        bus_write_1(sc->io_res, offset, value);
}

static u32
gmux_pio_read32(struct apple_gmux_softc *sc, uint8_t offset)
{
        return(bus_read_4(sc->io_res, offset));
}

#if 0  /* Defined but not used */
static void
gmux_pio_write32(struct apple_gmux_softc *sc, uint8_t offset,
                             uint32_t value)
{
        int i;
        u8 tmpval;

        for (i = 0; i < 4; i++) {
                tmpval = (value >> (i * 8)) & 0xff;
                bus_write_1(sc->io_res, offset + i, tmpval);
        }
}
#endif  /* Defined but not used */

static int
gmux_index_wait_ready(struct apple_gmux_softc *sc)
{
        int i = 200;
        u8 gwr = bus_read_1(sc->io_res, GMUX_PORT_WRITE);

        while (i && (gwr & 0x01)) {
                bus_read_1(sc->io_res, GMUX_PORT_READ);
                gwr = bus_read_1(sc->io_res, GMUX_PORT_WRITE);
                udelay(100);
                i--;
        }

        return !!i;
}

static int
gmux_index_wait_complete(struct apple_gmux_softc *sc)
{
        int i = 200;
        u8 gwr = bus_read_1(sc->io_res, GMUX_PORT_WRITE);

        while (i && !(gwr & 0x01)) {
                gwr = bus_read_1(sc->io_res, GMUX_PORT_WRITE);
                udelay(100);
                i--;
        }

        if (gwr & 0x01)
                bus_read_1(sc->io_res, GMUX_PORT_READ);

        return !!i;
}

static u8
gmux_index_read8(struct apple_gmux_softc *sc, uint8_t offset)
{
        u8 val;

        apple_gmux_lock(sc);
        gmux_index_wait_ready(sc);
        bus_write_1(sc->io_res, GMUX_PORT_READ, (offset & 0xff));
        gmux_index_wait_complete(sc);
        val = bus_read_1(sc->io_res, GMUX_PORT_VALUE);
        apple_gmux_unlock(sc);

        return val;
}

static void
gmux_index_write8(struct apple_gmux_softc *sc, int offset, uint8_t value)
{
        apple_gmux_lock(sc);
        bus_write_1(sc->io_res, GMUX_PORT_VALUE, value);
        gmux_index_wait_ready(sc);
        bus_write_1(sc->io_res, GMUX_PORT_WRITE, (offset & 0xff));
        gmux_index_wait_complete(sc);
        apple_gmux_unlock(sc);
}

static u32
gmux_index_read32(struct apple_gmux_softc *sc, uint8_t offset)
{
        u32 val;

        apple_gmux_lock(sc);
        gmux_index_wait_ready(sc);
        bus_write_1(sc->io_res, GMUX_PORT_READ, (offset & 0xff));
        gmux_index_wait_complete(sc);
        val = bus_read_4(sc->io_res, GMUX_PORT_VALUE);
        apple_gmux_unlock(sc);

        return val;
}

#if 0  /* Defined but not used */
static void
gmux_index_write32(struct apple_gmux_softc *sc, int offset, uint32_t value)
{
        int i;
        u8 tmpval;

        apple_gmux_lock(sc);

        for (i = 0; i < 4; i++) {
                tmpval = (value >> (i * 8)) & 0xff;
                bus_write_1(sc->io_res, GMUX_PORT_VALUE + i, tmpval);
        }

        gmux_index_wait_ready(sc);
        bus_write_1(sc->io_res, GMUX_PORT_WRITE, (offset & 0xff));
        gmux_index_wait_complete(sc);
        apple_gmux_unlock(sc);
}
#endif  /* Defined but not used */

static u8
gmux_read8(struct apple_gmux_softc *sc, int offset)
{
        if (sc->indexed)
                return gmux_index_read8(sc, offset);
        else
                return gmux_pio_read8(sc, offset);
}

static void
gmux_write8(struct apple_gmux_softc *sc, int offset, uint8_t value)
{
        if (sc->indexed)
                gmux_index_write8(sc, offset, value);
        else
                gmux_pio_write8(sc, offset, value);
}

static u32
gmux_read32(struct apple_gmux_softc *sc, int offset)
{
        if (sc->indexed)
                return gmux_index_read32(sc, offset);
        else
                return gmux_pio_read32(sc, offset);
}

#if 0  /* Defined but not used */
static void
gmux_write32(struct apple_gmux_softc *sc, int offset, uint32_t value)
{
        if (sc->indexed)
                gmux_index_write32(sc, offset, value);
        else
                gmux_pio_write32(sc, offset, value);
}
#endif  /* Defined but not used */

static bool
gmux_is_indexed(struct apple_gmux_softc *sc)
{
        u16 val;

        bus_write_1(sc->io_res, 0xcc, 0xaa);
        bus_write_1(sc->io_res, 0xcd, 0x55);
        bus_write_1(sc->io_res, 0xce, 0x00);

        val = bus_read_1(sc->io_res, 0xcc) |
                (bus_read_1(sc->io_res, 0xcd) << 8);

        if (val == 0x55aa)
                return true;

        return(false);
}

/**
 * DOC: Backlight control
 *
 * :3:  http://www.ti.com/lit/ds/symlink/lp8543.pdf
 * :4:  http://www.ti.com/lit/ds/symlink/lp8545.pdf
 *
 * On single GPU MacBooks, the PWM signal for the backlight is generated by
 * the GPU. On dual GPU MacBook Pros by contrast, either GPU may be suspended
 * to conserve energy. Hence the PWM signal needs to be generated by a separate
 * backlight driver which is controlled by gmux. The earliest generation
 * MBP5 2008/09 uses a {3}[TI LP8543] backlight driver. All newer models
 * use a {4}[TI LP8545].
 */

#if 0  /* no backlight */
static int
gmux_get_brightness(struct backlight_device *bd)
{
        struct apple_gmux_softc *sc = bl_get_data(bd);
        return gmux_read32(sc, GMUX_PORT_BRIGHTNESS) &
               GMUX_BRIGHTNESS_MASK;
}

static int
gmux_update_status(struct backlight_device *bd)
{
        struct apple_gmux_softc *sc = bl_get_data(bd);
        u32 brightness = bd->props.brightness;

        if (bd->props.state & BL_CORE_SUSPENDED)
                return 0;

        gmux_write32(sc, GMUX_PORT_BRIGHTNESS, brightness);

        return 0;
}

static const struct backlight_ops gmux_bl_ops = {
        .options = BL_CORE_SUSPENDRESUME,
        .get_brightness = gmux_get_brightness,
        .update_status = gmux_update_status,
};
#endif  /* no backlight */

/**
 * DOC: Graphics mux
 *
 * :5:  http://pimg-fpiw.uspto.gov/fdd/07/870/086/0.pdf
 * :6:  http://www.nxp.com/documents/data_sheet/CBTL06141.pdf
 * :7:  http://www.ti.com/lit/ds/symlink/hd3ss212.pdf
 * :8:  https://www.pericom.com/assets/Datasheets/PI3VDP12412.pdf
 * :9:  http://www.ti.com/lit/ds/symlink/sn74lv4066a.pdf
 * :10: http://pdf.datasheetarchive.com/indexerfiles/Datasheets-SW16/DSASW00308511.pdf
 * :11: http://www.ti.com/lit/ds/symlink/ts3ds10224.pdf
 *
 * On pre-retinas, the LVDS outputs of both GPUs feed into gmux which muxes
 * either of them to the panel. One of the tricks gmux has up its sleeve is
 * to lengthen the blanking interval of its output during a switch to
 * synchronize it with the GPU switched to. This allows for a flicker-free
 * switch that is imperceptible by the user ({5}[US 8,687,007 B2]).
 *
 * On retinas, muxing is no longer done by gmux itself, but by a separate
 * chip which is controlled by gmux. The chip is triple sourced, it is
 * either an {6}[NXP CBTL06142], {7}[TI HD3SS212] or {8}[Pericom PI3VDP12412].
 * The panel is driven with eDP instead of LVDS since the pixel clock
 * required for retina resolution exceeds LVDS' limits.
 *
 * Pre-retinas are able to switch the panel's DDC pins separately.
 * This is handled by a {9}[TI SN74LV4066A] which is controlled by gmux.
 * The inactive GPU can thus probe the panel's EDID without switching over
 * the entire panel. Retinas lack this functionality as the chips used for
 * eDP muxing are incapable of switching the AUX channel separately (see
 * the linked data sheets, Pericom would be capable but this is unused).
 * However the retina panel has the NO_AUX_HANDSHAKE_LINK_TRAINING bit set
 * in its DPCD, allowing the inactive GPU to skip the AUX handshake and
 * set up the output with link parameters pre-calibrated by the active GPU.
 *
 * The external DP port is only fully switchable on the first two unibody
 * MacBook Pro generations, MBP5 2008/09 and MBP6 2010. This is done by an
 * {6}[NXP CBTL06141] which is controlled by gmux. It's the predecessor of the
 * eDP mux on retinas, the difference being support for 2.7 versus 5.4 Gbit/s.
 *
 * The following MacBook Pro generations replaced the external DP port with a
 * combined DP/Thunderbolt port and lost the ability to switch it between GPUs,
 * connecting it either to the discrete GPU or the Thunderbolt controller.
 * Oddly enough, while the full port is no longer switchable, AUX and HPD
 * are still switchable by way of an {10}[NXP CBTL03062] (on pre-retinas
 * MBP8 2011 and MBP9 2012) or two {11}[TI TS3DS10224] (on retinas) under the
 * control of gmux. Since the integrated GPU is missing the main link,
 * external displays appear to it as phantoms which fail to link-train.
 *
 * gmux receives the HPD signal of all display connectors and sends an
 * interrupt on hotplug. On generations which cannot switch external ports,
 * the discrete GPU can then be woken to drive the newly connected display.
 * The ability to switch AUX on these generations could be used to improve
 * reliability of hotplug detection by having the integrated GPU poll the
 * ports while the discrete GPU is asleep, but currently we do not make use
 * of this feature.
 *
 * gmux' initial switch state on bootup is user configurable via the EFI
 * variable `gpu-power-prefs-fa4ce28d-b62f-4c99-9cc3-6815686e30f9` (5th byte,
 * 1 = IGD, 0 = DIS). Based on this setting, the EFI firmware tells gmux to
 * switch the panel and the external DP connector and allocates a framebuffer
 * for the selected GPU.
 */

static void
gmux_read_switch_state(struct apple_gmux_softc *sc)
{
        if (gmux_read8(sc, GMUX_PORT_SWITCH_DDC) == 1)
                sc->switch_state_ddc = VGA_SWITCHEROO_IGD;
        else
                sc->switch_state_ddc = VGA_SWITCHEROO_DIS;

        if (gmux_read8(sc, GMUX_PORT_SWITCH_DISPLAY) == 2)
                sc->switch_state_display = VGA_SWITCHEROO_IGD;
        else
                sc->switch_state_display = VGA_SWITCHEROO_DIS;

        if (gmux_read8(sc, GMUX_PORT_SWITCH_EXTERNAL) == 2)
                sc->switch_state_external = VGA_SWITCHEROO_IGD;
        else
                sc->switch_state_external = VGA_SWITCHEROO_DIS;
}

static void
gmux_write_switch_state(struct apple_gmux_softc *sc)
{
        if (sc->switch_state_ddc == VGA_SWITCHEROO_IGD)
                gmux_write8(sc, GMUX_PORT_SWITCH_DDC, 1);
        else
                gmux_write8(sc, GMUX_PORT_SWITCH_DDC, 2);

        if (sc->switch_state_display == VGA_SWITCHEROO_IGD)
                gmux_write8(sc, GMUX_PORT_SWITCH_DISPLAY, 2);
        else
                gmux_write8(sc, GMUX_PORT_SWITCH_DISPLAY, 3);

        if (sc->switch_state_external == VGA_SWITCHEROO_IGD)
                gmux_write8(sc, GMUX_PORT_SWITCH_EXTERNAL, 2);
        else
                gmux_write8(sc, GMUX_PORT_SWITCH_EXTERNAL, 3);
}

static int
gmux_switchto(enum vga_switcheroo_client_id id)
{
        apple_gmux_softc_data->switch_state_ddc = id;
        apple_gmux_softc_data->switch_state_display = id;
        apple_gmux_softc_data->switch_state_external = id;

        gmux_write_switch_state(apple_gmux_softc_data);

        return 0;
}

static int
gmux_switch_ddc(enum vga_switcheroo_client_id id)
{
        enum vga_switcheroo_client_id old_ddc_owner =
                apple_gmux_softc_data->switch_state_ddc;

        if (id == old_ddc_owner)
                return id;

        pr_debug("Switching DDC from %d to %d\n", old_ddc_owner, id);
        apple_gmux_softc_data->switch_state_ddc = id;

        if (id == VGA_SWITCHEROO_IGD)
                gmux_write8(apple_gmux_softc_data, GMUX_PORT_SWITCH_DDC, 1);
        else
                gmux_write8(apple_gmux_softc_data, GMUX_PORT_SWITCH_DDC, 2);

        return old_ddc_owner;
}

/**
 * DOC: Power control
 *
 * gmux is able to cut power to the discrete GPU. It automatically takes care
 * of the correct sequence to tear down and bring up the power rails for
 * core voltage, VRAM and PCIe.
 */

static int
gmux_set_discrete_state(struct apple_gmux_softc *sc,
                enum vga_switcheroo_state state)
{
        reinit_completion(&sc->powerchange_done);

        if (state == VGA_SWITCHEROO_ON) {
                gmux_write8(sc, GMUX_PORT_DISCRETE_POWER, 1);
                gmux_write8(sc, GMUX_PORT_DISCRETE_POWER, 3);
                pr_debug("Discrete card powered up\n");
        } else {
                gmux_write8(sc, GMUX_PORT_DISCRETE_POWER, 1);
                gmux_write8(sc, GMUX_PORT_DISCRETE_POWER, 0);
                pr_debug("Discrete card powered down\n");
        }

        sc->power_state = state;

        if (sc->gpe >= 0 &&
            !wait_for_completion_interruptible_timeout(&sc->powerchange_done,
                                                       msecs_to_jiffies(200)))
                pr_warn("Timeout waiting for gmux switch to complete\n");

        return 0;
}

static int
gmux_set_power_state(enum vga_switcheroo_client_id id,
                enum vga_switcheroo_state state)
{
        if (id == VGA_SWITCHEROO_IGD)
                return 0;

        return gmux_set_discrete_state(apple_gmux_softc_data, state);
}

static int
gmux_get_client_id(struct pci_dev *pdev)
{
        /*
         * Early Macbook Pros with switchable graphics use nvidia
         * integrated graphics. Hardcode that the 9400M is integrated.
         */
        if (pdev->vendor == PCI_VENDOR_ID_INTEL)
                return VGA_SWITCHEROO_IGD;
        else if (pdev->vendor == PCI_VENDOR_ID_NVIDIA &&
                 pdev->device == 0x0863)
                return VGA_SWITCHEROO_IGD;
        else
                return VGA_SWITCHEROO_DIS;
}

static const struct vga_switcheroo_handler gmux_handler_indexed = {
        .switchto = gmux_switchto,
        .power_state = gmux_set_power_state,
        .get_client_id = gmux_get_client_id,
};

static const struct vga_switcheroo_handler gmux_handler_classic = {
        .switchto = gmux_switchto,
        .switch_ddc = gmux_switch_ddc,
        .power_state = gmux_set_power_state,
        .get_client_id = gmux_get_client_id,
};

/**
 * DOC: Interrupt
 *
 * gmux is also connected to a GPIO pin of the southbridge and thereby is able
 * to trigger an ACPI GPE. On the MBP5 2008/09 it's GPIO pin 22 of the Nvidia
 * MCP79, on all following generations it's GPIO pin 6 of the Intel PCH.
 * The GPE merely signals that an interrupt occurred, the actual type of event
 * is identified by reading a gmux register.
 */

static inline void
gmux_disable_interrupts(struct apple_gmux_softc *sc)
{
        gmux_write8(sc, GMUX_PORT_INTERRUPT_ENABLE, GMUX_INTERRUPT_DISABLE);
}

static inline void
gmux_enable_interrupts(struct apple_gmux_softc *sc)
{
        gmux_write8(sc, GMUX_PORT_INTERRUPT_ENABLE, GMUX_INTERRUPT_ENABLE);
}

static inline u8
gmux_interrupt_get_status(struct apple_gmux_softc *sc)
{
        return gmux_read8(sc, GMUX_PORT_INTERRUPT_STATUS);
}

static void
gmux_clear_interrupts(struct apple_gmux_softc *sc)
{
        u8 status;

        /* to clear interrupts write back current status */
        status = gmux_interrupt_get_status(sc);
        gmux_write8(sc, GMUX_PORT_INTERRUPT_STATUS, status);
}

static void
gmux_notify_handler(ACPI_HANDLE device, UINT32 value, void *context)
{
        u8 status;
        device_t dev = context;
        struct apple_gmux_softc *sc = device_get_softc(dev);

        status = gmux_interrupt_get_status(sc);
        gmux_disable_interrupts(sc);
        pr_debug("Notify handler called: status %d\n", status);

        gmux_clear_interrupts(sc);
        gmux_enable_interrupts(sc);

        if (status & GMUX_INTERRUPT_STATUS_POWER)
                complete(&sc->powerchange_done);
}

static int
apple_gmux_suspend(device_t dev)
{
        /* XXX: TODO */

        return 0;
}

static int
apple_gmux_resume(device_t dev)
{
        /* XXX: TODO */

        return 0;
}

device_t
gmux_get_io_pdev(void)
{
        device_t pch = NULL;
        struct pci_devinfo *di = NULL;

        while ((pch = pci_iterate_class(&di, PCIC_DISPLAY, PCIS_DISPLAY_VGA))) {
                u16 cmd;

                cmd = (u16)pci_read_config(pch, PCIR_COMMAND, 2);
                if (!(cmd & PCIM_CMD_PORTEN))
                        continue;

                return(pch);
        }

        return(NULL);
}

static int
apple_gmux_probe(device_t dev)
{
        device_t bus;
        static char *gmux_ids[] = { GMUX_ACPI_HID, NULL };

        bus = device_get_parent(dev);

        if (ACPI_ID_PROBE(bus, dev, gmux_ids) == NULL)
                return(ENXIO);

        device_set_desc(dev, "apple gmux controller");

        return(BUS_PROBE_DEFAULT);
}

static int
apple_gmux_attach(device_t dev)
{
        struct apple_gmux_softc *sc;
        int unit;
        uint8_t ver_major, ver_minor, ver_release;
        int ret = -ENXIO;
        ACPI_STATUS status;
        UINT32 gpe;
        device_t pch_dev = NULL;

        sc = device_get_softc(dev);
        unit = device_get_unit(dev);

        sc->gmux_dev = dev;
        sc->unit = unit;

        sc->io_rid = 0;
        sc->io_res = bus_alloc_resource_any(dev, SYS_RES_IOPORT, &sc->io_rid,
                                            RF_ACTIVE);

        if (sc->io_res == NULL) {
                pr_err("Failed to find gmux I/O resource\n");
                return(ENXIO);
        }

        /*
         * Explicitly initialize sc->indexed, to be clear we assume
         * gmux is classic by default.
         */
        sc->indexed = false;

        /*
         * 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 = gmux_read8(sc, GMUX_PORT_VERSION_MAJOR);
        ver_minor = gmux_read8(sc, GMUX_PORT_VERSION_MINOR);
        ver_release = gmux_read8(sc, GMUX_PORT_VERSION_RELEASE);
        if (ver_major == 0xff && ver_minor == 0xff && ver_release == 0xff) {
                if (gmux_is_indexed(sc)) {
                        u32 version;
                        lockinit(&sc->lk, "apple_gmux", 0, 0);
                        sc->indexed = true;
                        version = gmux_read32(sc, GMUX_PORT_VERSION_MAJOR);
                        ver_major = (version >> 24) & 0xff;
                        ver_minor = (version >> 16) & 0xff;
                        ver_release = (version >> 8) & 0xff;
                } else {
                        pr_info("gmux device not present or IO disabled\n");
                        ret = -ENODEV;
                        goto err_release;
                }
        }
        pr_info("Found gmux version %d.%d.%d [%s]\n", ver_major, ver_minor,
                ver_release, (sc->indexed ? "indexed" : "classic"));

        /*
         * Apple systems with gmux are EFI based and normally don't use
         * VGA. In addition changing IO+MEM ownership between IGP and dGPU
         * disables IO/MEM used for backlight control on some systems.
         * Lock IO+MEM to GPU with active IO to prevent switch.
         */
        pch_dev = gmux_get_io_pdev();
        if (pch_dev == NULL) {
                ret = -ENODEV;
                pr_err("Cannot find PCI device\n");
                goto err_release;
        }

#if 0  /* collides with 915 */
        drm_init_pdev(pch_dev, &sc->pdev);
#endif

#if 0  /* no backlight infrastructure */
        memset(&props, 0, sizeof(props));
        props.type = BACKLIGHT_PLATFORM;
        props.max_brightness = gmux_read32(gmux_data, GMUX_PORT_MAX_BRIGHTNESS);

        /*
         * Currently it's assumed that the maximum brightness is less than
         * 2^24 for compatibility with old gmux versions. Cap the max
         * brightness at this value, but print a warning if the hardware
         * reports something higher so that it can be fixed.
         */
        if (WARN_ON(props.max_brightness > GMUX_MAX_BRIGHTNESS))
                props.max_brightness = GMUX_MAX_BRIGHTNESS;

        bdev = backlight_device_register("gmux_backlight", &pnp->dev,
                                         gmux_data, &gmux_bl_ops, &props);
        if (IS_ERR(bdev)) {
                ret = PTR_ERR(bdev);
                goto err_release;
        }

        gmux_data->bdev = bdev;
        bdev->props.brightness = gmux_get_brightness(bdev);
        backlight_update_status(bdev);

        /*
         * The backlight situation on Macs is complicated. If the gmux is
         * present it's the best choice, because it always works for
         * backlight control and supports more levels than other options.
         * Disable the other backlight choices.
         */
        acpi_video_set_dmi_backlight_type(acpi_backlight_vendor);
        apple_bl_unregister();
#endif  /* no backlight infrastructure */

        sc->power_state = VGA_SWITCHEROO_ON;

        sc->dhandle = acpi_get_handle(dev);
        if (!sc->dhandle) {
                pr_err("Cannot find acpi handle for pnp device %s\n",
                       device_get_name(dev));
                ret = -ENODEV;
                goto err_notify;
        }

        status = acpi_GetInteger(sc->dhandle, "GMGP", &gpe);
        if (ACPI_SUCCESS(status)) {
                sc->gpe = (int)gpe;

                status = AcpiInstallNotifyHandler(sc->dhandle,
                                                  ACPI_DEVICE_NOTIFY,
                                                  gmux_notify_handler, dev);

                if (ACPI_FAILURE(status)) {
                        pr_err("AcpiInstallNotifyHandler failed: %s\n",
                               AcpiFormatException(status));
                        ret = -ENODEV;
                        goto err_notify;
                }

                status = AcpiEnableGpe(NULL, sc->gpe);
                if (ACPI_FAILURE(status)) {
                        pr_err("AcpiEnableGpe failed: %s\n",
                               AcpiFormatException(status));
                        goto err_enable_gpe;
                }
        } else {
                pr_warn("No GPE found for gmux\n");
                sc->gpe = -1;
        }

        apple_gmux_softc_data = sc;
        init_completion(&sc->powerchange_done);
        gmux_enable_interrupts(sc);
        gmux_read_switch_state(sc);

        /*
         * Retina MacBook Pros cannot switch the panel's AUX separately
         * and need eDP pre-calibration. They are distinguishable from
         * pre-retinas by having an "indexed" gmux.
         *
         * Pre-retina MacBook Pros can switch the panel's DDC separately.
         */
        if (sc->indexed)
                ret = vga_switcheroo_register_handler(&gmux_handler_indexed,
                                              VGA_SWITCHEROO_NEEDS_EDP_CONFIG);
        else
                ret = vga_switcheroo_register_handler(&gmux_handler_classic,
                                              VGA_SWITCHEROO_CAN_SWITCH_DDC);
        if (ret) {
                pr_err("Failed to register vga_switcheroo handler\n");
                goto err_register_handler;
        }

        return 0;

err_register_handler:
        gmux_disable_interrupts(sc);
        apple_gmux_softc_data = NULL;
        if (sc->gpe >= 0)
                AcpiDisableGpe(NULL, sc->gpe);
err_enable_gpe:
        if (sc->gpe >= 0)
                AcpiRemoveNotifyHandler(sc->dhandle, ACPI_DEVICE_NOTIFY,
                                        gmux_notify_handler);
err_notify:
        /* backlight_device_unregister(bdev); */
err_release:
#if 0  /* collides with i915 */
        drm_fini_pdev(&sc->pdev);
#endif
        bus_release_resource(dev, SYS_RES_IOPORT, sc->io_rid, sc->io_res);

        return(ret);
}

static int
apple_gmux_detach(device_t dev)
{
        struct apple_gmux_softc *sc = device_get_softc(dev);

        vga_switcheroo_unregister_handler();
        gmux_disable_interrupts(sc);
        if (sc->gpe >= 0) {
                AcpiDisableGpe(NULL, sc->gpe);
                AcpiRemoveNotifyHandler(sc->dhandle, ACPI_DEVICE_NOTIFY,
                                        gmux_notify_handler);
        }

        apple_gmux_softc_data = NULL;
#if 0  /* collides with i915*/
        drm_fini_pdev(&sc->pdev);
#endif
        return(bus_release_resource(dev, SYS_RES_IOPORT,
            sc->io_rid, sc->io_res));
}

static device_method_t apple_gmux_methods[] = {
        DEVMETHOD(device_probe,         apple_gmux_probe),
        DEVMETHOD(device_attach,        apple_gmux_attach),
        DEVMETHOD(device_detach,        apple_gmux_detach),
        DEVMETHOD(device_resume,        apple_gmux_resume),
        DEVMETHOD(device_suspend,       apple_gmux_suspend),

        DEVMETHOD_END
};

devclass_t gmux_devclass;

static driver_t apple_gmux_driver = {
        "apple_gmux",
        apple_gmux_methods,
        sizeof(struct apple_gmux_softc)
};

DRIVER_MODULE(gmux, acpi, apple_gmux_driver, gmux_devclass, NULL, NULL);
MODULE_VERSION(apple_gmux, 1);
MODULE_DEPEND(apple_gmux, drm, 1, 1, 2);
MODULE_DEPEND(apple_gmux, vga_switcheroo, 1, 1, 2);