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

[Luke D. Jones]

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@xxxxxxxxxx>
---
 drivers/platform/x86/asus-wmi.c            | 92 ++++++++++++++++++++++
 include/linux/platform_data/x86/asus-wmi.h |  3 +
 2 files changed, 95 insertions(+)

diff --git a/drivers/platform/x86/asus-wmi.c b/drivers/platform/x86/asus-wmi.c
index 0e7fbed8a50d..25be8b422041 100644
--- a/drivers/platform/x86/asus-wmi.c
+++ b/drivers/platform/x86/asus-wmi.c
@@ -234,6 +234,9 @@ struct asus_wmi {
 	bool dgpu_disable_available;
 	bool dgpu_disable;
 
+	bool dgpu_only_available;
+	bool dgpu_only;
+
 	bool throttle_thermal_policy_available;
 	u8 throttle_thermal_policy_mode;
 
@@ -559,6 +562,87 @@ static void lid_flip_tablet_mode_get_state(struct asus_wmi *asus)
 	}
 }
 
+/* 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);
+
 /* dGPU ********************************************************************/
 static int dgpu_disable_check_present(struct asus_wmi *asus)
 {
@@ -3258,6 +3342,7 @@ 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_lid_resume.attr,
 	&dev_attr_als_enable.attr,
 	&dev_attr_fan_boost_mode.attr,
@@ -3288,6 +3373,8 @@ 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_fan_boost_mode.attr)
 		ok = asus->fan_boost_mode_available;
 	else if (attr == &dev_attr_throttle_thermal_policy.attr)
@@ -3557,6 +3644,10 @@ 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 = fan_boost_mode_check_present(asus);
 	if (err)
 		goto fail_fan_boost_mode;
@@ -3671,6 +3762,7 @@ static int asus_wmi_add(struct platform_device *pdev)
 fail_fan_boost_mode:
 fail_egpu_enable:
 fail_dgpu_disable:
+fail_dgpu_only:
 fail_platform:
 fail_panel_od:
 	kfree(asus);
diff --git a/include/linux/platform_data/x86/asus-wmi.h b/include/linux/platform_data/x86/asus-wmi.h
index a571b47ff362..f54d0e307d87 100644
--- a/include/linux/platform_data/x86/asus-wmi.h
+++ b/include/linux/platform_data/x86/asus-wmi.h
@@ -92,6 +92,9 @@
 /* Keyboard dock */
 #define ASUS_WMI_DEVID_KBD_DOCK		0x00120063
 
+/* Dedicated GPU only. When active the dGPU will be the only visible GPU */
+#define ASUS_WMI_DEVID_DEDICATED	0x00090016
+
 /* dgpu on/off */
 #define ASUS_WMI_DEVID_EGPU		0x00090019
 
-- 
2.37.1