Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 775 insertions, 0 deletions

diff --git a/drivers/platform/x86/apple-gmux.c b/drivers/platform/x86/apple-gmux.c
new file mode 100644
index 000000000..9333f82cf
--- /dev/null
+++ b/drivers/platform/x86/apple-gmux.c
@@ -0,0 +1,775 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  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>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/backlight.h>
+#include <linux/acpi.h>
+#include <linux/pnp.h>
+#include <linux/apple_bl.h>
+#include <linux/apple-gmux.h>
+#include <linux/slab.h>
+#include <linux/delay.h>
+#include <linux/pci.h>
+#include <linux/vga_switcheroo.h>
+#include <asm/io.h>
+
+/**
+ * DOC: Overview
+ *
+ * gmux is a microcontroller built into the MacBook Pro to support dual GPUs:
+ * A `Lattice XP2`_ on pre-retinas, a `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_``.
+ *
+ * .. _Lattice XP2:
+ *     http://www.latticesemi.com/en/Products/FPGAandCPLD/LatticeXP2.aspx
+ * .. _Renesas R4F2113:
+ *     http://www.renesas.com/products/mpumcu/h8s/h8s2100/h8s2113/index.jsp
+ */
+
+struct apple_gmux_data {
+	unsigned long iostart;
+	unsigned long iolen;
+	bool indexed;
+	struct mutex index_lock;
+
+	struct backlight_device *bdev;
+
+	/* switcheroo data */
+	acpi_handle dhandle;
+	int gpe;
+	bool external_switchable;
+	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_data *apple_gmux_data;
+
+#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
+
+static u8 gmux_pio_read8(struct apple_gmux_data *gmux_data, int port)
+{
+	return inb(gmux_data->iostart + port);
+}
+
+static void gmux_pio_write8(struct apple_gmux_data *gmux_data, int port,
+			       u8 val)
+{
+	outb(val, gmux_data->iostart + port);
+}
+
+static u32 gmux_pio_read32(struct apple_gmux_data *gmux_data, int port)
+{
+	return inl(gmux_data->iostart + port);
+}
+
+static void gmux_pio_write32(struct apple_gmux_data *gmux_data, int port,
+			     u32 val)
+{
+	int i;
+	u8 tmpval;
+
+	for (i = 0; i < 4; i++) {
+		tmpval = (val >> (i * 8)) & 0xff;
+		outb(tmpval, gmux_data->iostart + port + i);
+	}
+}
+
+static int gmux_index_wait_ready(struct apple_gmux_data *gmux_data)
+{
+	int i = 200;
+	u8 gwr = inb(gmux_data->iostart + GMUX_PORT_WRITE);
+
+	while (i && (gwr & 0x01)) {
+		inb(gmux_data->iostart + GMUX_PORT_READ);
+		gwr = inb(gmux_data->iostart + GMUX_PORT_WRITE);
+		udelay(100);
+		i--;
+	}
+
+	return !!i;
+}
+
+static int gmux_index_wait_complete(struct apple_gmux_data *gmux_data)
+{
+	int i = 200;
+	u8 gwr = inb(gmux_data->iostart + GMUX_PORT_WRITE);
+
+	while (i && !(gwr & 0x01)) {
+		gwr = inb(gmux_data->iostart + GMUX_PORT_WRITE);
+		udelay(100);
+		i--;
+	}
+
+	if (gwr & 0x01)
+		inb(gmux_data->iostart + GMUX_PORT_READ);
+
+	return !!i;
+}
+
+static u8 gmux_index_read8(struct apple_gmux_data *gmux_data, int port)
+{
+	u8 val;
+
+	mutex_lock(&gmux_data->index_lock);
+	gmux_index_wait_ready(gmux_data);
+	outb((port & 0xff), gmux_data->iostart + GMUX_PORT_READ);
+	gmux_index_wait_complete(gmux_data);
+	val = inb(gmux_data->iostart + GMUX_PORT_VALUE);
+	mutex_unlock(&gmux_data->index_lock);
+
+	return val;
+}
+
+static void gmux_index_write8(struct apple_gmux_data *gmux_data, int port,
+			      u8 val)
+{
+	mutex_lock(&gmux_data->index_lock);
+	outb(val, gmux_data->iostart + GMUX_PORT_VALUE);
+	gmux_index_wait_ready(gmux_data);
+	outb(port & 0xff, gmux_data->iostart + GMUX_PORT_WRITE);
+	gmux_index_wait_complete(gmux_data);
+	mutex_unlock(&gmux_data->index_lock);
+}
+
+static u32 gmux_index_read32(struct apple_gmux_data *gmux_data, int port)
+{
+	u32 val;
+
+	mutex_lock(&gmux_data->index_lock);
+	gmux_index_wait_ready(gmux_data);
+	outb((port & 0xff), gmux_data->iostart + GMUX_PORT_READ);
+	gmux_index_wait_complete(gmux_data);
+	val = inl(gmux_data->iostart + GMUX_PORT_VALUE);
+	mutex_unlock(&gmux_data->index_lock);
+
+	return val;
+}
+
+static void gmux_index_write32(struct apple_gmux_data *gmux_data, int port,
+			       u32 val)
+{
+	int i;
+	u8 tmpval;
+
+	mutex_lock(&gmux_data->index_lock);
+
+	for (i = 0; i < 4; i++) {
+		tmpval = (val >> (i * 8)) & 0xff;
+		outb(tmpval, gmux_data->iostart + GMUX_PORT_VALUE + i);
+	}
+
+	gmux_index_wait_ready(gmux_data);
+	outb(port & 0xff, gmux_data->iostart + GMUX_PORT_WRITE);
+	gmux_index_wait_complete(gmux_data);
+	mutex_unlock(&gmux_data->index_lock);
+}
+
+static u8 gmux_read8(struct apple_gmux_data *gmux_data, int port)
+{
+	if (gmux_data->indexed)
+		return gmux_index_read8(gmux_data, port);
+	else
+		return gmux_pio_read8(gmux_data, port);
+}
+
+static void gmux_write8(struct apple_gmux_data *gmux_data, int port, u8 val)
+{
+	if (gmux_data->indexed)
+		gmux_index_write8(gmux_data, port, val);
+	else
+		gmux_pio_write8(gmux_data, port, val);
+}
+
+static u32 gmux_read32(struct apple_gmux_data *gmux_data, int port)
+{
+	if (gmux_data->indexed)
+		return gmux_index_read32(gmux_data, port);
+	else
+		return gmux_pio_read32(gmux_data, port);
+}
+
+static void gmux_write32(struct apple_gmux_data *gmux_data, int port,
+			     u32 val)
+{
+	if (gmux_data->indexed)
+		gmux_index_write32(gmux_data, port, val);
+	else
+		gmux_pio_write32(gmux_data, port, val);
+}
+
+/**
+ * DOC: Backlight control
+ *
+ * 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 `TI LP8543`_ backlight driver. All newer models
+ * use a `TI LP8545`_.
+ *
+ * .. _TI LP8543: https://www.ti.com/lit/ds/symlink/lp8543.pdf
+ * .. _TI LP8545: https://www.ti.com/lit/ds/symlink/lp8545.pdf
+ */
+
+static int gmux_get_brightness(struct backlight_device *bd)
+{
+	struct apple_gmux_data *gmux_data = bl_get_data(bd);
+	return gmux_read32(gmux_data, GMUX_PORT_BRIGHTNESS) &
+	       GMUX_BRIGHTNESS_MASK;
+}
+
+static int gmux_update_status(struct backlight_device *bd)
+{
+	struct apple_gmux_data *gmux_data = bl_get_data(bd);
+	u32 brightness = backlight_get_brightness(bd);
+
+	gmux_write32(gmux_data, 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,
+};
+
+/**
+ * DOC: Graphics mux
+ *
+ * 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 (`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 `NXP CBTL06142`_, `TI HD3SS212`_ or `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 `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
+ * `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 `NXP CBTL03062`_ (on pre-retinas
+ * MBP8 2011 and MBP9 2012) or two `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.
+ *
+ * Our switching policy for the external port is that on those generations
+ * which are able to switch it fully, the port is switched together with the
+ * panel when IGD / DIS commands are issued to vga_switcheroo. It is thus
+ * possible to drive e.g. a beamer on battery power with the integrated GPU.
+ * The user may manually switch to the discrete GPU if more performance is
+ * needed.
+ *
+ * On all newer generations, the external port can only be driven by the
+ * discrete GPU. If a display is plugged in while the panel is switched to
+ * the integrated GPU, *both* GPUs will be in use for maximum performance.
+ * To decrease power consumption, the user may manually switch to the
+ * discrete GPU, thereby suspending the integrated GPU.
+ *
+ * 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.
+ *
+ * .. _US 8,687,007 B2: https://pimg-fpiw.uspto.gov/fdd/07/870/086/0.pdf
+ * .. _NXP CBTL06141:   https://www.nxp.com/documents/data_sheet/CBTL06141.pdf
+ * .. _NXP CBTL06142:   https://www.nxp.com/documents/data_sheet/CBTL06141.pdf
+ * .. _TI HD3SS212:     https://www.ti.com/lit/ds/symlink/hd3ss212.pdf
+ * .. _Pericom PI3VDP12412: https://www.pericom.com/assets/Datasheets/PI3VDP12412.pdf
+ * .. _TI SN74LV4066A:  https://www.ti.com/lit/ds/symlink/sn74lv4066a.pdf
+ * .. _NXP CBTL03062:   http://pdf.datasheetarchive.com/indexerfiles/Datasheets-SW16/DSASW00308511.pdf
+ * .. _TI TS3DS10224:   https://www.ti.com/lit/ds/symlink/ts3ds10224.pdf
+ */
+
+static void gmux_read_switch_state(struct apple_gmux_data *gmux_data)
+{
+	if (gmux_read8(gmux_data, GMUX_PORT_SWITCH_DDC) == 1)
+		gmux_data->switch_state_ddc = VGA_SWITCHEROO_IGD;
+	else
+		gmux_data->switch_state_ddc = VGA_SWITCHEROO_DIS;
+
+	if (gmux_read8(gmux_data, GMUX_PORT_SWITCH_DISPLAY) == 2)
+		gmux_data->switch_state_display = VGA_SWITCHEROO_IGD;
+	else
+		gmux_data->switch_state_display = VGA_SWITCHEROO_DIS;
+
+	if (gmux_read8(gmux_data, GMUX_PORT_SWITCH_EXTERNAL) == 2)
+		gmux_data->switch_state_external = VGA_SWITCHEROO_IGD;
+	else
+		gmux_data->switch_state_external = VGA_SWITCHEROO_DIS;
+}
+
+static void gmux_write_switch_state(struct apple_gmux_data *gmux_data)
+{
+	if (gmux_data->switch_state_ddc == VGA_SWITCHEROO_IGD)
+		gmux_write8(gmux_data, GMUX_PORT_SWITCH_DDC, 1);
+	else
+		gmux_write8(gmux_data, GMUX_PORT_SWITCH_DDC, 2);
+
+	if (gmux_data->switch_state_display == VGA_SWITCHEROO_IGD)
+		gmux_write8(gmux_data, GMUX_PORT_SWITCH_DISPLAY, 2);
+	else
+		gmux_write8(gmux_data, GMUX_PORT_SWITCH_DISPLAY, 3);
+
+	if (gmux_data->switch_state_external == VGA_SWITCHEROO_IGD)
+		gmux_write8(gmux_data, GMUX_PORT_SWITCH_EXTERNAL, 2);
+	else
+		gmux_write8(gmux_data, GMUX_PORT_SWITCH_EXTERNAL, 3);
+}
+
+static int gmux_switchto(enum vga_switcheroo_client_id id)
+{
+	apple_gmux_data->switch_state_ddc = id;
+	apple_gmux_data->switch_state_display = id;
+	if (apple_gmux_data->external_switchable)
+		apple_gmux_data->switch_state_external = id;
+
+	gmux_write_switch_state(apple_gmux_data);
+
+	return 0;
+}
+
+static int gmux_switch_ddc(enum vga_switcheroo_client_id id)
+{
+	enum vga_switcheroo_client_id old_ddc_owner =
+		apple_gmux_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_data->switch_state_ddc = id;
+
+	if (id == VGA_SWITCHEROO_IGD)
+		gmux_write8(apple_gmux_data, GMUX_PORT_SWITCH_DDC, 1);
+	else
+		gmux_write8(apple_gmux_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_data *gmux_data,
+				   enum vga_switcheroo_state state)
+{
+	reinit_completion(&gmux_data->powerchange_done);
+
+	if (state == VGA_SWITCHEROO_ON) {
+		gmux_write8(gmux_data, GMUX_PORT_DISCRETE_POWER, 1);
+		gmux_write8(gmux_data, GMUX_PORT_DISCRETE_POWER, 3);
+		pr_debug("Discrete card powered up\n");
+	} else {
+		gmux_write8(gmux_data, GMUX_PORT_DISCRETE_POWER, 1);
+		gmux_write8(gmux_data, GMUX_PORT_DISCRETE_POWER, 0);
+		pr_debug("Discrete card powered down\n");
+	}
+
+	gmux_data->power_state = state;
+
+	if (gmux_data->gpe >= 0 &&
+	    !wait_for_completion_interruptible_timeout(&gmux_data->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_data, state);
+}
+
+static enum vga_switcheroo_client_id 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_data *gmux_data)
+{
+	gmux_write8(gmux_data, GMUX_PORT_INTERRUPT_ENABLE,
+		    GMUX_INTERRUPT_DISABLE);
+}
+
+static inline void gmux_enable_interrupts(struct apple_gmux_data *gmux_data)
+{
+	gmux_write8(gmux_data, GMUX_PORT_INTERRUPT_ENABLE,
+		    GMUX_INTERRUPT_ENABLE);
+}
+
+static inline u8 gmux_interrupt_get_status(struct apple_gmux_data *gmux_data)
+{
+	return gmux_read8(gmux_data, GMUX_PORT_INTERRUPT_STATUS);
+}
+
+static void gmux_clear_interrupts(struct apple_gmux_data *gmux_data)
+{
+	u8 status;
+
+	/* to clear interrupts write back current status */
+	status = gmux_interrupt_get_status(gmux_data);
+	gmux_write8(gmux_data, GMUX_PORT_INTERRUPT_STATUS, status);
+}
+
+static void gmux_notify_handler(acpi_handle device, u32 value, void *context)
+{
+	u8 status;
+	struct pnp_dev *pnp = (struct pnp_dev *)context;
+	struct apple_gmux_data *gmux_data = pnp_get_drvdata(pnp);
+
+	status = gmux_interrupt_get_status(gmux_data);
+	gmux_disable_interrupts(gmux_data);
+	pr_debug("Notify handler called: status %d\n", status);
+
+	gmux_clear_interrupts(gmux_data);
+	gmux_enable_interrupts(gmux_data);
+
+	if (status & GMUX_INTERRUPT_STATUS_POWER)
+		complete(&gmux_data->powerchange_done);
+}
+
+static int gmux_suspend(struct device *dev)
+{
+	struct pnp_dev *pnp = to_pnp_dev(dev);
+	struct apple_gmux_data *gmux_data = pnp_get_drvdata(pnp);
+
+	gmux_disable_interrupts(gmux_data);
+	return 0;
+}
+
+static int gmux_resume(struct device *dev)
+{
+	struct pnp_dev *pnp = to_pnp_dev(dev);
+	struct apple_gmux_data *gmux_data = pnp_get_drvdata(pnp);
+
+	gmux_enable_interrupts(gmux_data);
+	gmux_write_switch_state(gmux_data);
+	if (gmux_data->power_state == VGA_SWITCHEROO_OFF)
+		gmux_set_discrete_state(gmux_data, gmux_data->power_state);
+	return 0;
+}
+
+static int is_thunderbolt(struct device *dev, void *data)
+{
+	return to_pci_dev(dev)->is_thunderbolt;
+}
+
+static int gmux_probe(struct pnp_dev *pnp, const struct pnp_device_id *id)
+{
+	struct apple_gmux_data *gmux_data;
+	struct resource *res;
+	struct backlight_properties props;
+	struct backlight_device *bdev;
+	u8 ver_major, ver_minor, ver_release;
+	int ret = -ENXIO;
+	acpi_status status;
+	unsigned long long gpe;
+	bool indexed = false;
+	u32 version;
+
+	if (apple_gmux_data)
+		return -EBUSY;
+
+	if (!apple_gmux_detect(pnp, &indexed)) {
+		pr_info("gmux device not present\n");
+		return -ENODEV;
+	}
+
+	gmux_data = kzalloc(sizeof(*gmux_data), GFP_KERNEL);
+	if (!gmux_data)
+		return -ENOMEM;
+	pnp_set_drvdata(pnp, gmux_data);
+
+	res = pnp_get_resource(pnp, IORESOURCE_IO, 0);
+	gmux_data->iostart = res->start;
+	gmux_data->iolen = resource_size(res);
+
+	if (!request_region(gmux_data->iostart, gmux_data->iolen,
+			    "Apple gmux")) {
+		pr_err("gmux I/O already in use\n");
+		goto err_free;
+	}
+
+	if (indexed) {
+		mutex_init(&gmux_data->index_lock);
+		gmux_data->indexed = true;
+		version = gmux_read32(gmux_data, GMUX_PORT_VERSION_MAJOR);
+		ver_major = (version >> 24) & 0xff;
+		ver_minor = (version >> 16) & 0xff;
+		ver_release = (version >> 8) & 0xff;
+	} else {
+		ver_major = gmux_read8(gmux_data, GMUX_PORT_VERSION_MAJOR);
+		ver_minor = gmux_read8(gmux_data, GMUX_PORT_VERSION_MINOR);
+		ver_release = gmux_read8(gmux_data, GMUX_PORT_VERSION_RELEASE);
+	}
+	pr_info("Found gmux version %d.%d.%d [%s]\n", ver_major, ver_minor,
+		ver_release, (gmux_data->indexed ? "indexed" : "classic"));
+
+	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.
+	 */
+	apple_bl_unregister();
+
+	gmux_data->power_state = VGA_SWITCHEROO_ON;
+
+	gmux_data->dhandle = ACPI_HANDLE(&pnp->dev);
+	if (!gmux_data->dhandle) {
+		pr_err("Cannot find acpi handle for pnp device %s\n",
+		       dev_name(&pnp->dev));
+		ret = -ENODEV;
+		goto err_notify;
+	}
+
+	status = acpi_evaluate_integer(gmux_data->dhandle, "GMGP", NULL, &gpe);
+	if (ACPI_SUCCESS(status)) {
+		gmux_data->gpe = (int)gpe;
+
+		status = acpi_install_notify_handler(gmux_data->dhandle,
+						     ACPI_DEVICE_NOTIFY,
+						     &gmux_notify_handler, pnp);
+		if (ACPI_FAILURE(status)) {
+			pr_err("Install notify handler failed: %s\n",
+			       acpi_format_exception(status));
+			ret = -ENODEV;
+			goto err_notify;
+		}
+
+		status = acpi_enable_gpe(NULL, gmux_data->gpe);
+		if (ACPI_FAILURE(status)) {
+			pr_err("Cannot enable gpe: %s\n",
+			       acpi_format_exception(status));
+			goto err_enable_gpe;
+		}
+	} else {
+		pr_warn("No GPE found for gmux\n");
+		gmux_data->gpe = -1;
+	}
+
+	/*
+	 * If Thunderbolt is present, the external DP port is not fully
+	 * switchable. Force its AUX channel to the discrete GPU.
+	 */
+	gmux_data->external_switchable =
+		!bus_for_each_dev(&pci_bus_type, NULL, NULL, is_thunderbolt);
+	if (!gmux_data->external_switchable)
+		gmux_write8(gmux_data, GMUX_PORT_SWITCH_EXTERNAL, 3);
+
+	apple_gmux_data = gmux_data;
+	init_completion(&gmux_data->powerchange_done);
+	gmux_enable_interrupts(gmux_data);
+	gmux_read_switch_state(gmux_data);
+
+	/*
+	 * 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 (gmux_data->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(gmux_data);
+	apple_gmux_data = NULL;
+	if (gmux_data->gpe >= 0)
+		acpi_disable_gpe(NULL, gmux_data->gpe);
+err_enable_gpe:
+	if (gmux_data->gpe >= 0)
+		acpi_remove_notify_handler(gmux_data->dhandle,
+					   ACPI_DEVICE_NOTIFY,
+					   &gmux_notify_handler);
+err_notify:
+	backlight_device_unregister(bdev);
+err_release:
+	release_region(gmux_data->iostart, gmux_data->iolen);
+err_free:
+	kfree(gmux_data);
+	return ret;
+}
+
+static void gmux_remove(struct pnp_dev *pnp)
+{
+	struct apple_gmux_data *gmux_data = pnp_get_drvdata(pnp);
+
+	vga_switcheroo_unregister_handler();
+	gmux_disable_interrupts(gmux_data);
+	if (gmux_data->gpe >= 0) {
+		acpi_disable_gpe(NULL, gmux_data->gpe);
+		acpi_remove_notify_handler(gmux_data->dhandle,
+					   ACPI_DEVICE_NOTIFY,
+					   &gmux_notify_handler);
+	}
+
+	backlight_device_unregister(gmux_data->bdev);
+
+	release_region(gmux_data->iostart, gmux_data->iolen);
+	apple_gmux_data = NULL;
+	kfree(gmux_data);
+
+	apple_bl_register();
+}
+
+static const struct pnp_device_id gmux_device_ids[] = {
+	{GMUX_ACPI_HID, 0},
+	{"", 0}
+};
+
+static const struct dev_pm_ops gmux_dev_pm_ops = {
+	.suspend = gmux_suspend,
+	.resume = gmux_resume,
+};
+
+static struct pnp_driver gmux_pnp_driver = {
+	.name		= "apple-gmux",
+	.probe		= gmux_probe,
+	.remove		= gmux_remove,
+	.id_table	= gmux_device_ids,
+	.driver		= {
+			.pm = &gmux_dev_pm_ops,
+	},
+};
+
+module_pnp_driver(gmux_pnp_driver);
+MODULE_AUTHOR("Seth Forshee <seth.forshee@canonical.com>");
+MODULE_DESCRIPTION("Apple Gmux Driver");
+MODULE_LICENSE("GPL");
+MODULE_DEVICE_TABLE(pnp, gmux_device_ids);