1 files changed, 69 insertions, 29 deletions

diff --git a/drivers/hwmon/nct6775-platform.c b/drivers/hwmon/nct6775-platform.c
index bf43f73dc835..e5d4a79cd5f7 100644
--- a/drivers/hwmon/nct6775-platform.c
+++ b/drivers/hwmon/nct6775-platform.c
@@ -17,7 +17,6 @@
 #include <linux/module.h>
 #include <linux/platform_device.h>
 #include <linux/regmap.h>
-#include <linux/wmi.h>
 
 #include "nct6775.h"
 
@@ -107,40 +106,50 @@ struct nct6775_sio_data {
 	void (*sio_exit)(struct nct6775_sio_data *sio_data);
 };
 
-#define ASUSWMI_MONITORING_GUID		"466747A0-70EC-11DE-8A39-0800200C9A66"
+#define ASUSWMI_METHOD			"WMBD"
 #define ASUSWMI_METHODID_RSIO		0x5253494F
 #define ASUSWMI_METHODID_WSIO		0x5753494F
 #define ASUSWMI_METHODID_RHWM		0x5248574D
 #define ASUSWMI_METHODID_WHWM		0x5748574D
 #define ASUSWMI_UNSUPPORTED_METHOD	0xFFFFFFFE
+#define ASUSWMI_DEVICE_HID		"PNP0C14"
+#define ASUSWMI_DEVICE_UID		"ASUSWMI"
+
+#if IS_ENABLED(CONFIG_ACPI)
+/*
+ * ASUS boards have only one device with WMI "WMBD" method and have provided
+ * access to only one SuperIO chip at 0x0290.
+ */
+static struct acpi_device *asus_acpi_dev;
+#endif
 
 static int nct6775_asuswmi_evaluate_method(u32 method_id, u8 bank, u8 reg, u8 val, u32 *retval)
 {
-#if IS_ENABLED(CONFIG_ACPI_WMI)
+#if IS_ENABLED(CONFIG_ACPI)
+	acpi_handle handle = acpi_device_handle(asus_acpi_dev);
 	u32 args = bank | (reg << 8) | (val << 16);
-	struct acpi_buffer input = { (acpi_size) sizeof(args), &args };
-	struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
+	struct acpi_object_list input;
+	union acpi_object params[3];
+	unsigned long long result;
 	acpi_status status;
-	union acpi_object *obj;
-	u32 tmp = ASUSWMI_UNSUPPORTED_METHOD;
-
-	status = wmi_evaluate_method(ASUSWMI_MONITORING_GUID, 0,
-				     method_id, &input, &output);
 
+	params[0].type = ACPI_TYPE_INTEGER;
+	params[0].integer.value = 0;
+	params[1].type = ACPI_TYPE_INTEGER;
+	params[1].integer.value = method_id;
+	params[2].type = ACPI_TYPE_BUFFER;
+	params[2].buffer.length = sizeof(args);
+	params[2].buffer.pointer = (void *)&args;
+	input.count = 3;
+	input.pointer = params;
+
+	status = acpi_evaluate_integer(handle, ASUSWMI_METHOD, &input, &result);
 	if (ACPI_FAILURE(status))
 		return -EIO;
 
-	obj = output.pointer;
-	if (obj && obj->type == ACPI_TYPE_INTEGER)
-		tmp = obj->integer.value;
-
 	if (retval)
-		*retval = tmp;
+		*retval = (u32)result & 0xFFFFFFFF;
 
-	kfree(obj);
-
-	if (tmp == ASUSWMI_UNSUPPORTED_METHOD)
-		return -ENODEV;
 	return 0;
 #else
 	return -EOPNOTSUPP;
@@ -1099,6 +1108,45 @@ static const char * const asus_wmi_boards[] = {
 	"TUF GAMING Z490-PLUS (WI-FI)",
 };
 
+#if IS_ENABLED(CONFIG_ACPI)
+/*
+ * Callback for acpi_bus_for_each_dev() to find the right device
+ * by _UID and _HID and return 1 to stop iteration.
+ */
+static int nct6775_asuswmi_device_match(struct device *dev, void *data)
+{
+	struct acpi_device *adev = to_acpi_device(dev);
+	const char *uid = acpi_device_uid(adev);
+	const char *hid = acpi_device_hid(adev);
+
+	if (hid && !strcmp(hid, ASUSWMI_DEVICE_HID) && uid && !strcmp(uid, data)) {
+		asus_acpi_dev = adev;
+		return 1;
+	}
+
+	return 0;
+}
+#endif
+
+static enum sensor_access nct6775_determine_access(const char *device_uid)
+{
+#if IS_ENABLED(CONFIG_ACPI)
+	u8 tmp;
+
+	acpi_bus_for_each_dev(nct6775_asuswmi_device_match, (void *)device_uid);
+	if (!asus_acpi_dev)
+		return access_direct;
+
+	/* if reading chip id via ACPI succeeds, use WMI "WMBD" method for access */
+	if (!nct6775_asuswmi_read(0, NCT6775_PORT_CHIPID, &tmp) && tmp) {
+		pr_debug("Using Asus WMBD method of %s to access %#x chip.\n", device_uid, tmp);
+		return access_asuswmi;
+	}
+#endif
+
+	return access_direct;
+}
+
 static int __init sensors_nct6775_platform_init(void)
 {
 	int i, err;
@@ -1109,7 +1157,6 @@ static int __init sensors_nct6775_platform_init(void)
 	int sioaddr[2] = { 0x2e, 0x4e };
 	enum sensor_access access = access_direct;
 	const char *board_vendor, *board_name;
-	u8 tmp;
 
 	err = platform_driver_register(&nct6775_driver);
 	if (err)
@@ -1122,15 +1169,8 @@ static int __init sensors_nct6775_platform_init(void)
 	    !strcmp(board_vendor, "ASUSTeK COMPUTER INC.")) {
 		err = match_string(asus_wmi_boards, ARRAY_SIZE(asus_wmi_boards),
 				   board_name);
-		if (err >= 0) {
-			/* if reading chip id via WMI succeeds, use WMI */
-			if (!nct6775_asuswmi_read(0, NCT6775_PORT_CHIPID, &tmp) && tmp) {
-				pr_info("Using Asus WMI to access %#x chip.\n", tmp);
-				access = access_asuswmi;
-			} else {
-				pr_err("Can't read ChipID by Asus WMI.\n");
-			}
-		}
+		if (err >= 0)
+			access = nct6775_determine_access(ASUSWMI_DEVICE_UID);
 	}
 
 	/*