[PATCH v11 16/18] platform/x86: asus-armoury: pick the eGPU activation from the reported GPU

[Denis Benato <denis.benato@linux.dev>]

The egpu_enable attribute is a switch: writing 0 turns the eGPU off
and writing 1 turns it on. Turning it on has always sent the NVIDIA
activation value, which only works for NVIDIA stations, and the WMI
interface cannot tell which GPU is installed in the connected one.

Let drivers that detect the station report the GPU vendor through
asus-wmi: writing 1 sends the activation value matching the reported
vendor and falls back to NVIDIA when nothing has been reported, so
existing tools keep working unchanged on every station.

Signed-off-by: Denis Benato <denis.benato@linux.dev>
---
 drivers/platform/x86/asus-armoury.c        | 53 +++++++++++++---------
 drivers/platform/x86/asus-wmi.c            | 29 ++++++++++++
 include/linux/platform_data/x86/asus-wmi.h | 11 +++++
 3 files changed, 71 insertions(+), 22 deletions(-)

diff --git a/drivers/platform/x86/asus-armoury.c b/drivers/platform/x86/asus-armoury.c
index fb382de5b57b..6cc5f0f6b3f5 100644
--- a/drivers/platform/x86/asus-armoury.c
+++ b/drivers/platform/x86/asus-armoury.c
@@ -538,13 +538,27 @@ static ssize_t dgpu_disable_current_value_store(struct kobject *kobj,
 ASUS_WMI_SHOW_INT(dgpu_disable_current_value, ASUS_WMI_DEVID_DGPU);
 ASUS_ATTR_GROUP_BOOL(dgpu_disable, "dgpu_disable", "Disable the dGPU");
 
-/* Values map for eGPU activation requests. */
-static u32 egpu_status_map[] = {
-	[0] = 0x00000000U,
-	[1] = 0x00000001U,
-	[2] = 0x00000101U,
-	[3] = 0x00000201U,
-};
+/*
+ * egpu_default_enable_value() - Activation value for the connected station
+ *
+ * The eGPU switch activation value selects the vendor of the external
+ * GPU: 0x0001 activates NVIDIA, 0x0101 AMD and 0x0201 Intel. Pick the
+ * value matching the GPU vendor reported for the connected station,
+ * and fall back to NVIDIA when no vendor has been reported.
+ *
+ * Return: the activation value for the reported GPU vendor
+ */
+static u32 egpu_default_enable_value(void)
+{
+	switch (asus_wmi_egpu_vendor()) {
+	case PCI_VENDOR_ID_ATI:
+		return 0x0101;
+	case PCI_VENDOR_ID_INTEL:
+		return 0x0201;
+	default:
+		return 0x0001;
+	}
+}
 
 /*
  * armoury_pci_rescan() - Performs a PCI rescan
@@ -578,9 +592,14 @@ static ssize_t egpu_enable_current_value_store(struct kobject *kobj, struct kobj
 	if (err)
 		return err;
 
-	if (requested >= ARRAY_SIZE(egpu_status_map))
+	if (requested > 1)
 		return -EINVAL;
-	enable = egpu_status_map[requested];
+
+	/*
+	 * 0 deactivates the eGPU, 1 activates it with the value matching
+	 * the GPU reported for the connected station.
+	 */
+	enable = requested ? egpu_default_enable_value() : 0;
 
 	scoped_guard(mutex, &asus_armoury.egpu_mutex) {
 		/* Ensure the eGPU is connected before attempting to activate it. */
@@ -661,7 +680,7 @@ static ssize_t egpu_enable_current_value_store(struct kobject *kobj, struct kobj
 static ssize_t egpu_enable_current_value_show(struct kobject *kobj, struct kobj_attribute *attr,
 						char *buf)
 {
-	int i, err;
+	int err;
 	u32 status;
 
 	scoped_guard(mutex, &asus_armoury.egpu_mutex) {
@@ -670,20 +689,10 @@ static ssize_t egpu_enable_current_value_show(struct kobject *kobj, struct kobj_
 			return err;
 	}
 
-	for (i = 0; i < ARRAY_SIZE(egpu_status_map); i++) {
-		if (egpu_status_map[i] == status)
-			return sysfs_emit(buf, "%u\n", i);
-	}
-
-	return -EIO;
+	return sysfs_emit(buf, "%u\n", status != 0);
 }
 
-static ssize_t egpu_enable_possible_values_show(struct kobject *kobj, struct kobj_attribute *attr,
-						char *buf)
-{
-	return armoury_attr_enum_list(buf, ARRAY_SIZE(egpu_status_map));
-}
-ASUS_ATTR_GROUP_ENUM(egpu_enable, "egpu_enable", "Enable the eGPU (also disables dGPU)");
+ASUS_ATTR_GROUP_BOOL(egpu_enable, "egpu_enable", "Enable the eGPU (also disables dGPU)");
 
 /* Device memory available to APU */
 
diff --git a/drivers/platform/x86/asus-wmi.c b/drivers/platform/x86/asus-wmi.c
index a65090429ca7..40b4cf32c0ac 100644
--- a/drivers/platform/x86/asus-wmi.c
+++ b/drivers/platform/x86/asus-wmi.c
@@ -881,6 +881,35 @@ static DEVICE_ATTR_RW(dgpu_disable);
 #endif /* IS_ENABLED(CONFIG_ASUS_WMI_DEPRECATED_ATTRS) */
 
 /* eGPU ********************************************************************/
+
+static u16 egpu_gpu_vendor;
+
+/**
+ * asus_wmi_egpu_set_vendor() - Report the vendor of the external GPU
+ * @vendor: PCI vendor ID of the GPU installed in the connected eGPU
+ * station, or 0 to fall back to the default activation value
+ *
+ * Drivers that detect an eGPU station report the vendor of the GPU
+ * they found so that the eGPU activation can use the matching value.
+ */
+void asus_wmi_egpu_set_vendor(u16 vendor)
+{
+	egpu_gpu_vendor = vendor;
+}
+EXPORT_SYMBOL_NS_GPL(asus_wmi_egpu_set_vendor, "ASUS_WMI");
+
+/**
+ * asus_wmi_egpu_vendor() - Vendor of the external GPU
+ *
+ * Return: the PCI vendor ID last reported with
+ * asus_wmi_egpu_set_vendor(), or 0 when no station is known
+ */
+u16 asus_wmi_egpu_vendor(void)
+{
+	return egpu_gpu_vendor;
+}
+EXPORT_SYMBOL_NS_GPL(asus_wmi_egpu_vendor, "ASUS_WMI");
+
 #if IS_ENABLED(CONFIG_ASUS_WMI_DEPRECATED_ATTRS)
 static ssize_t egpu_enable_show(struct device *dev,
 				   struct device_attribute *attr, char *buf)
diff --git a/include/linux/platform_data/x86/asus-wmi.h b/include/linux/platform_data/x86/asus-wmi.h
index b5ed8c83ace1..a53b2828bb1d 100644
--- a/include/linux/platform_data/x86/asus-wmi.h
+++ b/include/linux/platform_data/x86/asus-wmi.h
@@ -204,6 +204,8 @@ int asus_hid_register_listener(struct asus_hid_listener *cdev);
 void asus_hid_unregister_listener(struct asus_hid_listener *cdev);
 int asus_hid_event(enum asus_hid_event event);
 bool asus_wmi_custom_fan_curve_is_enabled(void);
+void asus_wmi_egpu_set_vendor(u16 vendor);
+u16 asus_wmi_egpu_vendor(void);
 #else
 static inline void set_ally_mcu_hack(enum asus_ally_mcu_hack status)
 {
@@ -239,6 +241,15 @@ static inline bool asus_wmi_custom_fan_curve_is_enabled(void)
 {
 	return false;
 }
+
+static inline void asus_wmi_egpu_set_vendor(u16 vendor)
+{
+}
+
+static inline u16 asus_wmi_egpu_vendor(void)
+{
+	return 0;
+}
 #endif
 
 #endif	/* __PLATFORM_DATA_X86_ASUS_WMI_H */
-- 
2.47.3