[PATCH v2 6/6] asus-wmi: Add support for dGPU-only mode

["Luke D. Jones" <luke@ljones.dev>]

Adds support for a dGPU-only mode on some laptops where when enabled
the boot GPU is the dGPU, and the iGPU is not visible.

Signed-off-by: Luke D. Jones <luke@ljones.dev>
---
 .../ABI/testing/sysfs-platform-asus-wmi       |  9 ++
 drivers/platform/x86/asus-wmi.c               | 92 +++++++++++++++++++
 include/linux/platform_data/x86/asus-wmi.h    |  3 +
 3 files changed, 104 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-platform-asus-wmi b/Documentation/ABI/testing/sysfs-platform-asus-wmi
index 66b262476d92..93d111a65313 100644
--- a/Documentation/ABI/testing/sysfs-platform-asus-wmi
+++ b/Documentation/ABI/testing/sysfs-platform-asus-wmi
@@ -77,6 +77,15 @@ Description:
 			* 0 - Disable,
 			* 1 - Enable,
 
+What:		/sys/devices/platform/<platform>/dgpu_only
+Date:		Aug 2022
+KernelVersion:	6.0
+Contact:	"Luke Jones" <luke@ljones.dev>
+Description:
+		Set the dGPU to be the only GPU available:
+			* 0 - Disable,
+			* 1 - Enable,
+
 What:		/sys/devices/platform/<platform>/panel_od
 Date:		Aug 2022
 KernelVersion:	5.17
diff --git a/drivers/platform/x86/asus-wmi.c b/drivers/platform/x86/asus-wmi.c
index b9e5d87e3e18..840299828512 100644
--- a/drivers/platform/x86/asus-wmi.c
+++ b/drivers/platform/x86/asus-wmi.c
@@ -246,6 +246,9 @@ struct asus_wmi {
 	bool dgpu_disable_available;
 	bool dgpu_disable;
 
+	bool dgpu_only_available;
+	bool dgpu_only;
+
 	bool keyboard_rgb_state_available;
 	bool keyboard_rgb_mode_available;
 	struct keyboard_rgb_led keyboard_rgb_mode;
@@ -750,6 +753,87 @@ static ssize_t egpu_enable_store(struct device *dev,
 
 static DEVICE_ATTR_RW(egpu_enable);
 
+/* dedicated GPU only *********************************************************/
+static int dgpu_only_check_present(struct asus_wmi *asus)
+{
+	u32 result;
+	int err;
+
+	asus->dgpu_only_available = false;
+
+	err = asus_wmi_get_devstate(asus, ASUS_WMI_DEVID_DGPU, &result);
+	if (err) {
+		if (err == -ENODEV)
+			return 0;
+		return err;
+	}
+
+	if (result & ASUS_WMI_DSTS_PRESENCE_BIT) {
+		asus->dgpu_only_available = true;
+		asus->dgpu_only = result & ASUS_WMI_DSTS_STATUS_BIT;
+	}
+
+	return 0;
+}
+
+static int dgpu_only_write(struct asus_wmi *asus)
+{
+	u32 retval;
+	u8 value;
+	int err;
+
+	/* Don't rely on type conversion */
+	value = asus->dgpu_only ? 1 : 0;
+
+	err = asus_wmi_set_devstate(ASUS_WMI_DEVID_DGPU, value, &retval);
+	if (err) {
+		pr_warn("Failed to set dGPU-only mode: %d\n", err);
+		return err;
+	}
+
+	if (retval > 1) {
+		pr_warn("Failed to set dGPU-only mode (retval): 0x%x\n", retval);
+		return -EIO;
+	}
+
+	sysfs_notify(&asus->platform_device->dev.kobj, NULL, "dgpu_only");
+
+	return 0;
+}
+
+static ssize_t dgpu_only_show(struct device *dev,
+				   struct device_attribute *attr, char *buf)
+{
+	struct asus_wmi *asus = dev_get_drvdata(dev);
+	u8 mode = asus->dgpu_only;
+
+	return sysfs_emit(buf, "%d\n", mode);
+}
+
+static ssize_t dgpu_only_store(struct device *dev,
+				    struct device_attribute *attr,
+				    const char *buf, size_t count)
+{
+	bool enable;
+	int result;
+
+	struct asus_wmi *asus = dev_get_drvdata(dev);
+
+	result = kstrtobool(buf, &enable);
+	if (result)
+		return result;
+
+	asus->dgpu_only = enable;
+
+	result = dgpu_only_write(asus);
+	if (result)
+		return result;
+
+	return count;
+}
+
+static DEVICE_ATTR_RW(dgpu_only);
+
 /* TUF Laptop Keyboard RGB Modes **********************************************/
 static int keyboard_rgb_mode_check_present(struct asus_wmi *asus)
 {
@@ -3473,6 +3557,7 @@ static struct attribute *platform_attributes[] = {
 	&dev_attr_touchpad.attr,
 	&dev_attr_egpu_enable.attr,
 	&dev_attr_dgpu_disable.attr,
+	&dev_attr_dgpu_only.attr,
 	&dev_attr_keyboard_rgb_mode.attr,
 	&dev_attr_keyboard_rgb_mode_index.attr,
 	&dev_attr_keyboard_rgb_state.attr,
@@ -3507,6 +3592,8 @@ static umode_t asus_sysfs_is_visible(struct kobject *kobj,
 		ok = asus->egpu_enable_available;
 	else if (attr == &dev_attr_dgpu_disable.attr)
 		ok = asus->dgpu_disable_available;
+	else if (attr == &dev_attr_dgpu_only.attr)
+		ok = asus->dgpu_only_available;
 	else if (attr == &dev_attr_keyboard_rgb_mode.attr)
 		ok = asus->keyboard_rgb_mode_available;
 	else if (attr == &dev_attr_keyboard_rgb_mode_index.attr)
@@ -3784,6 +3871,10 @@ static int asus_wmi_add(struct platform_device *pdev)
 	if (err)
 		goto fail_dgpu_disable;
 
+	err = dgpu_only_check_present(asus);
+	if (err)
+		goto fail_dgpu_only;
+
 	err = keyboard_rgb_mode_check_present(asus);
 	if (err)
 		goto fail_keyboard_rgb_mode;
@@ -3906,6 +3997,7 @@ static int asus_wmi_add(struct platform_device *pdev)
 fail_fan_boost_mode:
 fail_egpu_enable:
 fail_dgpu_disable:
+fail_dgpu_only:
 fail_keyboard_rgb_mode:
 fail_keyboard_rgb_state:
 fail_platform:
diff --git a/include/linux/platform_data/x86/asus-wmi.h b/include/linux/platform_data/x86/asus-wmi.h
index b5c966798ef8..76b0756a0666 100644
--- a/include/linux/platform_data/x86/asus-wmi.h
+++ b/include/linux/platform_data/x86/asus-wmi.h
@@ -98,6 +98,9 @@
 /* dgpu on/off */
 #define ASUS_WMI_DEVID_DGPU		0x00090020
 
+/* Dedicated GPU only. When active the dGPU will be the only visible GPU */
+#define ASUS_WMI_DEVID_DEDICATED	0x00090016
+
 /* TUF laptop RGB control */
 #define ASUS_WMI_DEVID_TUF_RGB_MODE	0x00100056
 /* TUF laptop RGB state control */
-- 
2.37.1