Merge tag 'platform-drivers-x86-v6.2-3' of git://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86

Pull x86 platform driver fixes from Hans de Goede:

 -  Fix false positive apple_gmux backlight detection on older iGPU only
    MacBook models

 -  Various other small fixes and hardware-id additions

* tag 'platform-drivers-x86-v6.2-3' of git://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86:
  platform/x86: thinkpad_acpi: Fix profile modes on Intel platforms
  ACPI: video: Fix apple gmux detection
  platform/x86: apple-gmux: Add apple_gmux_detect() helper
  platform/x86: apple-gmux: Move port defines to apple-gmux.h
  platform/x86: hp-wmi: Fix cast to smaller integer type warning
  platform/x86/amd: pmc: Add a module parameter to disable workarounds
  platform/x86/amd: pmc: Disable IRQ1 wakeup for RN/CZN
  platform/x86: asus-wmi: Fix kbd_dock_devid tablet-switch reporting
  platform/x86: gigabyte-wmi: add support for B450M DS3H WIFI-CF
  platform/x86: hp-wmi: Handle Omen Key event
  platform/x86: dell-wmi: Add a keymap for KEY_MUTE in type 0x0010 table

9 files changed, 211 insertions, 111 deletions

diff --git a/drivers/acpi/video_detect.c b/drivers/acpi/video_detect.c
index 65cec7bb6d96..8626869c4904 100644
--- a/drivers/acpi/video_detect.c
+++ b/drivers/acpi/video_detect.c
@@ -110,26 +110,6 @@ static bool nvidia_wmi_ec_supported(void)
 }
 #endif
 
-static bool apple_gmux_backlight_present(void)
-{
-	struct acpi_device *adev;
-	struct device *dev;
-
-	adev = acpi_dev_get_first_match_dev(GMUX_ACPI_HID, NULL, -1);
-	if (!adev)
-		return false;
-
-	dev = acpi_get_first_physical_node(adev);
-	if (!dev)
-		return false;
-
-	/*
-	 * drivers/platform/x86/apple-gmux.c only supports old style
-	 * Apple GMUX with an IO-resource.
-	 */
-	return pnp_get_resource(to_pnp_dev(dev), IORESOURCE_IO, 0) != NULL;
-}
-
 /* Force to use vendor driver when the ACPI device is known to be
  * buggy */
 static int video_detect_force_vendor(const struct dmi_system_id *d)
@@ -766,6 +746,7 @@ static enum acpi_backlight_type __acpi_video_get_backlight_type(bool native)
 {
 	static DEFINE_MUTEX(init_mutex);
 	static bool nvidia_wmi_ec_present;
+	static bool apple_gmux_present;
 	static bool native_available;
 	static bool init_done;
 	static long video_caps;
@@ -779,6 +760,7 @@ static enum acpi_backlight_type __acpi_video_get_backlight_type(bool native)
 				    ACPI_UINT32_MAX, find_video, NULL,
 				    &video_caps, NULL);
 		nvidia_wmi_ec_present = nvidia_wmi_ec_supported();
+		apple_gmux_present = apple_gmux_detect(NULL, NULL);
 		init_done = true;
 	}
 	if (native)
@@ -800,7 +782,7 @@ static enum acpi_backlight_type __acpi_video_get_backlight_type(bool native)
 	if (nvidia_wmi_ec_present)
 		return acpi_backlight_nvidia_wmi_ec;
 
-	if (apple_gmux_backlight_present())
+	if (apple_gmux_present)
 		return acpi_backlight_apple_gmux;
 
 	/* Use ACPI video if available, except when native should be preferred. */
diff --git a/drivers/platform/x86/amd/pmc.c b/drivers/platform/x86/amd/pmc.c
index 8d924986381b..3cbb01ec10e3 100644
--- a/drivers/platform/x86/amd/pmc.c
+++ b/drivers/platform/x86/amd/pmc.c
@@ -22,6 +22,7 @@
 #include <linux/pci.h>
 #include <linux/platform_device.h>
 #include <linux/rtc.h>
+#include <linux/serio.h>
 #include <linux/suspend.h>
 #include <linux/seq_file.h>
 #include <linux/uaccess.h>
@@ -160,6 +161,10 @@ static bool enable_stb;
 module_param(enable_stb, bool, 0644);
 MODULE_PARM_DESC(enable_stb, "Enable the STB debug mechanism");
 
+static bool disable_workarounds;
+module_param(disable_workarounds, bool, 0644);
+MODULE_PARM_DESC(disable_workarounds, "Disable workarounds for platform bugs");
+
 static struct amd_pmc_dev pmc;
 static int amd_pmc_send_cmd(struct amd_pmc_dev *dev, u32 arg, u32 *data, u8 msg, bool ret);
 static int amd_pmc_read_stb(struct amd_pmc_dev *dev, u32 *buf);
@@ -653,6 +658,33 @@ static int amd_pmc_get_os_hint(struct amd_pmc_dev *dev)
 	return -EINVAL;
 }
 
+static int amd_pmc_czn_wa_irq1(struct amd_pmc_dev *pdev)
+{
+	struct device *d;
+	int rc;
+
+	if (!pdev->major) {
+		rc = amd_pmc_get_smu_version(pdev);
+		if (rc)
+			return rc;
+	}
+
+	if (pdev->major > 64 || (pdev->major == 64 && pdev->minor > 65))
+		return 0;
+
+	d = bus_find_device_by_name(&serio_bus, NULL, "serio0");
+	if (!d)
+		return 0;
+	if (device_may_wakeup(d)) {
+		dev_info_once(d, "Disabling IRQ1 wakeup source to avoid platform firmware bug\n");
+		disable_irq_wake(1);
+		device_set_wakeup_enable(d, false);
+	}
+	put_device(d);
+
+	return 0;
+}
+
 static int amd_pmc_verify_czn_rtc(struct amd_pmc_dev *pdev, u32 *arg)
 {
 	struct rtc_device *rtc_device;
@@ -715,8 +747,8 @@ static void amd_pmc_s2idle_prepare(void)
 	/* Reset and Start SMU logging - to monitor the s0i3 stats */
 	amd_pmc_setup_smu_logging(pdev);
 
-	/* Activate CZN specific RTC functionality */
-	if (pdev->cpu_id == AMD_CPU_ID_CZN) {
+	/* Activate CZN specific platform bug workarounds */
+	if (pdev->cpu_id == AMD_CPU_ID_CZN && !disable_workarounds) {
 		rc = amd_pmc_verify_czn_rtc(pdev, &arg);
 		if (rc) {
 			dev_err(pdev->dev, "failed to set RTC: %d\n", rc);
@@ -782,6 +814,25 @@ static struct acpi_s2idle_dev_ops amd_pmc_s2idle_dev_ops = {
 	.check = amd_pmc_s2idle_check,
 	.restore = amd_pmc_s2idle_restore,
 };
+
+static int __maybe_unused amd_pmc_suspend_handler(struct device *dev)
+{
+	struct amd_pmc_dev *pdev = dev_get_drvdata(dev);
+
+	if (pdev->cpu_id == AMD_CPU_ID_CZN && !disable_workarounds) {
+		int rc = amd_pmc_czn_wa_irq1(pdev);
+
+		if (rc) {
+			dev_err(pdev->dev, "failed to adjust keyboard wakeup: %d\n", rc);
+			return rc;
+		}
+	}
+
+	return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(amd_pmc_pm, amd_pmc_suspend_handler, NULL);
+
 #endif
 
 static const struct pci_device_id pmc_pci_ids[] = {
@@ -980,6 +1031,9 @@ static struct platform_driver amd_pmc_driver = {
 		.name = "amd_pmc",
 		.acpi_match_table = amd_pmc_acpi_ids,
 		.dev_groups = pmc_groups,
+#ifdef CONFIG_SUSPEND
+		.pm = &amd_pmc_pm,
+#endif
 	},
 	.probe = amd_pmc_probe,
 	.remove = amd_pmc_remove,
diff --git a/drivers/platform/x86/apple-gmux.c b/drivers/platform/x86/apple-gmux.c
index ca33df7ea550..9333f82cfa8a 100644
--- a/drivers/platform/x86/apple-gmux.c
+++ b/drivers/platform/x86/apple-gmux.c
@@ -64,29 +64,6 @@ struct apple_gmux_data {
 
 static struct apple_gmux_data *apple_gmux_data;
 
-/*
- * 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
 
@@ -249,23 +226,6 @@ static void gmux_write32(struct apple_gmux_data *gmux_data, int port,
 		gmux_pio_write32(gmux_data, port, val);
 }
 
-static bool gmux_is_indexed(struct apple_gmux_data *gmux_data)
-{
-	u16 val;
-
-	outb(0xaa, gmux_data->iostart + 0xcc);
-	outb(0x55, gmux_data->iostart + 0xcd);
-	outb(0x00, gmux_data->iostart + 0xce);
-
-	val = inb(gmux_data->iostart + 0xcc) |
-		(inb(gmux_data->iostart + 0xcd) << 8);
-
-	if (val == 0x55aa)
-		return true;
-
-	return false;
-}
-
 /**
  * DOC: Backlight control
  *
@@ -605,60 +565,43 @@ static int gmux_probe(struct pnp_dev *pnp, const struct pnp_device_id *id)
 	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);
-	if (!res) {
-		pr_err("Failed to find gmux I/O resource\n");
-		goto err_free;
-	}
-
 	gmux_data->iostart = res->start;
 	gmux_data->iolen = resource_size(res);
 
-	if (gmux_data->iolen < GMUX_MIN_IO_LEN) {
-		pr_err("gmux I/O region too small (%lu < %u)\n",
-		       gmux_data->iolen, GMUX_MIN_IO_LEN);
-		goto err_free;
-	}
-
 	if (!request_region(gmux_data->iostart, gmux_data->iolen,
 			    "Apple gmux")) {
 		pr_err("gmux I/O already in use\n");
 		goto err_free;
 	}
 
-	/*
-	 * 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(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);
-	if (ver_major == 0xff && ver_minor == 0xff && ver_release == 0xff) {
-		if (gmux_is_indexed(gmux_data)) {
-			u32 version;
-			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 {
-			pr_info("gmux device not present\n");
-			ret = -ENODEV;
-			goto err_release;
-		}
+	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"));
diff --git a/drivers/platform/x86/asus-wmi.c b/drivers/platform/x86/asus-wmi.c
index 104188d70988..1038dfdcdd32 100644
--- a/drivers/platform/x86/asus-wmi.c
+++ b/drivers/platform/x86/asus-wmi.c
@@ -225,6 +225,7 @@ struct asus_wmi {
 
 	int tablet_switch_event_code;
 	u32 tablet_switch_dev_id;
+	bool tablet_switch_inverted;
 
 	enum fan_type fan_type;
 	enum fan_type gpu_fan_type;
@@ -493,6 +494,13 @@ static bool asus_wmi_dev_is_present(struct asus_wmi *asus, u32 dev_id)
 }
 
 /* Input **********************************************************************/
+static void asus_wmi_tablet_sw_report(struct asus_wmi *asus, bool value)
+{
+	input_report_switch(asus->inputdev, SW_TABLET_MODE,
+			    asus->tablet_switch_inverted ? !value : value);
+	input_sync(asus->inputdev);
+}
+
 static void asus_wmi_tablet_sw_init(struct asus_wmi *asus, u32 dev_id, int event_code)
 {
 	struct device *dev = &asus->platform_device->dev;
@@ -501,7 +509,7 @@ static void asus_wmi_tablet_sw_init(struct asus_wmi *asus, u32 dev_id, int event
 	result = asus_wmi_get_devstate_simple(asus, dev_id);
 	if (result >= 0) {
 		input_set_capability(asus->inputdev, EV_SW, SW_TABLET_MODE);
-		input_report_switch(asus->inputdev, SW_TABLET_MODE, result);
+		asus_wmi_tablet_sw_report(asus, result);
 		asus->tablet_switch_dev_id = dev_id;
 		asus->tablet_switch_event_code = event_code;
 	} else if (result == -ENODEV) {
@@ -534,6 +542,7 @@ static int asus_wmi_input_init(struct asus_wmi *asus)
 	case asus_wmi_no_tablet_switch:
 		break;
 	case asus_wmi_kbd_dock_devid:
+		asus->tablet_switch_inverted = true;
 		asus_wmi_tablet_sw_init(asus, ASUS_WMI_DEVID_KBD_DOCK, NOTIFY_KBD_DOCK_CHANGE);
 		break;
 	case asus_wmi_lid_flip_devid:
@@ -573,10 +582,8 @@ static void asus_wmi_tablet_mode_get_state(struct asus_wmi *asus)
 		return;
 
 	result = asus_wmi_get_devstate_simple(asus, asus->tablet_switch_dev_id);
-	if (result >= 0) {
-		input_report_switch(asus->inputdev, SW_TABLET_MODE, result);
-		input_sync(asus->inputdev);
-	}
+	if (result >= 0)
+		asus_wmi_tablet_sw_report(asus, result);
 }
 
 /* dGPU ********************************************************************/
diff --git a/drivers/platform/x86/dell/dell-wmi-base.c b/drivers/platform/x86/dell/dell-wmi-base.c
index 0a259a27459f..502783a7adb1 100644
--- a/drivers/platform/x86/dell/dell-wmi-base.c
+++ b/drivers/platform/x86/dell/dell-wmi-base.c
@@ -261,6 +261,9 @@ static const struct key_entry dell_wmi_keymap_type_0010[] = {
 	{ KE_KEY,    0x57, { KEY_BRIGHTNESSDOWN } },
 	{ KE_KEY,    0x58, { KEY_BRIGHTNESSUP } },
 
+	/*Speaker Mute*/
+	{ KE_KEY, 0x109, { KEY_MUTE} },
+
 	/* Mic mute */
 	{ KE_KEY, 0x150, { KEY_MICMUTE } },
 
diff --git a/drivers/platform/x86/gigabyte-wmi.c b/drivers/platform/x86/gigabyte-wmi.c
index 5e7e6659a849..322cfaeda17b 100644
--- a/drivers/platform/x86/gigabyte-wmi.c
+++ b/drivers/platform/x86/gigabyte-wmi.c
@@ -141,6 +141,7 @@ static u8 gigabyte_wmi_detect_sensor_usability(struct wmi_device *wdev)
 
 static const struct dmi_system_id gigabyte_wmi_known_working_platforms[] = {
 	DMI_EXACT_MATCH_GIGABYTE_BOARD_NAME("B450M DS3H-CF"),
+	DMI_EXACT_MATCH_GIGABYTE_BOARD_NAME("B450M DS3H WIFI-CF"),
 	DMI_EXACT_MATCH_GIGABYTE_BOARD_NAME("B450M S2H V2"),
 	DMI_EXACT_MATCH_GIGABYTE_BOARD_NAME("B550 AORUS ELITE AX V2"),
 	DMI_EXACT_MATCH_GIGABYTE_BOARD_NAME("B550 AORUS ELITE"),
diff --git a/drivers/platform/x86/hp/hp-wmi.c b/drivers/platform/x86/hp/hp-wmi.c
index 0a99058be813..2ef201b625b3 100644
--- a/drivers/platform/x86/hp/hp-wmi.c
+++ b/drivers/platform/x86/hp/hp-wmi.c
@@ -90,6 +90,7 @@ enum hp_wmi_event_ids {
 	HPWMI_PEAKSHIFT_PERIOD		= 0x0F,
 	HPWMI_BATTERY_CHARGE_PERIOD	= 0x10,
 	HPWMI_SANITIZATION_MODE		= 0x17,
+	HPWMI_OMEN_KEY			= 0x1D,
 	HPWMI_SMART_EXPERIENCE_APP	= 0x21,
 };
 
@@ -216,6 +217,8 @@ static const struct key_entry hp_wmi_keymap[] = {
 	{ KE_KEY, 0x213b,  { KEY_INFO } },
 	{ KE_KEY, 0x2169,  { KEY_ROTATE_DISPLAY } },
 	{ KE_KEY, 0x216a,  { KEY_SETUP } },
+	{ KE_KEY, 0x21a5,  { KEY_PROG2 } }, /* HP Omen Key */
+	{ KE_KEY, 0x21a7,  { KEY_FN_ESC } },
 	{ KE_KEY, 0x21a9,  { KEY_TOUCHPAD_OFF } },
 	{ KE_KEY, 0x121a9, { KEY_TOUCHPAD_ON } },
 	{ KE_KEY, 0x231b,  { KEY_HELP } },
@@ -548,7 +551,7 @@ static int __init hp_wmi_enable_hotkeys(void)
 
 static int hp_wmi_set_block(void *data, bool blocked)
 {
-	enum hp_wmi_radio r = (enum hp_wmi_radio) data;
+	enum hp_wmi_radio r = (long)data;
 	int query = BIT(r + 8) | ((!blocked) << r);
 	int ret;
 
@@ -810,6 +813,7 @@ static void hp_wmi_notify(u32 value, void *context)
 	case HPWMI_SMART_ADAPTER:
 		break;
 	case HPWMI_BEZEL_BUTTON:
+	case HPWMI_OMEN_KEY:
 		key_code = hp_wmi_read_int(HPWMI_HOTKEY_QUERY);
 		if (key_code < 0)
 			break;
diff --git a/drivers/platform/x86/thinkpad_acpi.c b/drivers/platform/x86/thinkpad_acpi.c
index a95946800ae9..02860c32625e 100644
--- a/drivers/platform/x86/thinkpad_acpi.c
+++ b/drivers/platform/x86/thinkpad_acpi.c
@@ -10496,8 +10496,7 @@ static int dytc_profile_set(struct platform_profile_handler *pprof,
 			if (err)
 				goto unlock;
 		}
-	}
-	if (dytc_capabilities & BIT(DYTC_FC_PSC)) {
+	} else if (dytc_capabilities & BIT(DYTC_FC_PSC)) {
 		err = dytc_command(DYTC_SET_COMMAND(DYTC_FUNCTION_PSC, perfmode, 1), &output);
 		if (err)
 			goto unlock;
@@ -10525,14 +10524,16 @@ static void dytc_profile_refresh(void)
 			err = dytc_command(DYTC_CMD_MMC_GET, &output);
 		else
 			err = dytc_cql_command(DYTC_CMD_GET, &output);
-	} else if (dytc_capabilities & BIT(DYTC_FC_PSC))
+		funcmode = DYTC_FUNCTION_MMC;
+	} else if (dytc_capabilities & BIT(DYTC_FC_PSC)) {
 		err = dytc_command(DYTC_CMD_GET, &output);
-
+		/* Check if we are PSC mode, or have AMT enabled */
+		funcmode = (output >> DYTC_GET_FUNCTION_BIT) & 0xF;
+	}
 	mutex_unlock(&dytc_mutex);
 	if (err)
 		return;
 
-	funcmode = (output >> DYTC_GET_FUNCTION_BIT) & 0xF;
 	perfmode = (output >> DYTC_GET_MODE_BIT) & 0xF;
 	convert_dytc_to_profile(funcmode, perfmode, &profile);
 	if (profile != dytc_current_profile) {
diff --git a/include/linux/apple-gmux.h b/include/linux/apple-gmux.h
index ddb10aa67b14..1f68b49bcd68 100644
--- a/include/linux/apple-gmux.h
+++ b/include/linux/apple-gmux.h
@@ -8,18 +8,118 @@
 #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_present() - detect if gmux is built into the machine
+ * 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 is present and the kernel was configured
+ * 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)
@@ -34,6 +134,11 @@ 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 */