hwmon: (nct6775) Support access via Asus WMI

Support accessing the NCT677x via Asus WMI functions.

On mainboards that support this way of accessing the chip, the driver will
usually not work without this option since in these mainboards, ACPI will
mark the I/O port as used.

Code uses ACPI firmware interface to communicate with sensors with ASUS
motherboards:
* PRIME B460-PLUS,
* ROG CROSSHAIR VIII IMPACT,
* ROG STRIX B550-E GAMING,
* ROG STRIX B550-F GAMING,
* ROG STRIX B550-F GAMING (WI-FI),
* ROG STRIX Z490-I GAMING,
* TUF GAMING B550M-PLUS,
* TUF GAMING B550M-PLUS (WI-FI),
* TUF GAMING B550-PLUS,
* TUF GAMING X570-PLUS,
* TUF GAMING X570-PRO (WI-FI).

BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=204807Signed-off-by: Denis Pauk <pauk.denis@gmail.com>
Co-developed-by: Bernhard Seibold <mail@bernhard-seibold.de>
Signed-off-by: Bernhard Seibold <mail@bernhard-seibold.de>
Tested-by: Pär Ekholm <pehlm@pekholm.org>
Tested-by: <to.eivind@gmail.com>
Tested-by: Artem S. Tashkinov <aros@gmx.com>
Tested-by: Vittorio Roberto Alfieri <me@rebtoor.com>
Tested-by: Sahan Fernando <sahan.h.fernando@gmail.com>
Cc: Andy Shevchenko <andriy.shevchenko@intel.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20210917220240.56553-4-pauk.denis@gmail.comSigned-off-by: Guenter Roeck <linux@roeck-us.net>

drivers/hwmon/Kconfig

@@ -1443,6 +1443,7 @@ config SENSORS_NCT6683
 config SENSORS_NCT6775
 	tristate "Nuvoton NCT6775F and compatibles"
 	depends on !PPC
+	depends on ACPI_WMI || ACPI_WMI=n
 	select HWMON_VID
 	help
 	  If you say yes here you get support for the hardware monitoring

drivers/hwmon/nct6775.c

@@ -55,6 +55,7 @@
 #include <linux/dmi.h>
 #include <linux/io.h>
 #include <linux/nospec.h>
+#include <linux/wmi.h>
 #include "lm75.h"
 
 #define USE_ALTERNATE
@@ -132,10 +133,13 @@ MODULE_PARM_DESC(fan_debounce, "Enable debouncing for fan RPM signal");
 #define SIO_ID_MASK		0xFFF8
 
 enum pwm_enable { off, manual, thermal_cruise, speed_cruise, sf3, sf4 };
+enum sensor_access { access_direct, access_asuswmi };
 
 struct nct6775_sio_data {
 	int sioreg;
+	int ld;
 	enum kinds kind;
+	enum sensor_access access;
 
 	/* superio_() callbacks  */
 	void (*sio_outb)(struct nct6775_sio_data *sio_data, int reg, int val);
@@ -145,6 +149,91 @@ struct nct6775_sio_data {
 	void (*sio_exit)(struct nct6775_sio_data *sio_data);
 };
 
+#define ASUSWMI_MONITORING_GUID		"466747A0-70EC-11DE-8A39-0800200C9A66"
+#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
+
+static int nct6775_asuswmi_evaluate_method(u32 method_id, u8 bank, u8 reg, u8 val, u32 *retval)
+{
+#if IS_ENABLED(CONFIG_ACPI_WMI)
+	u32 args = bank | (reg << 8) | (val << 16);
+	struct acpi_buffer input = { (acpi_size) sizeof(args), &args };
+	struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
+	acpi_status status;
+	union acpi_object *obj;
+	u32 tmp = ASUSWMI_UNSUPPORTED_METHOD;
+
+	status = wmi_evaluate_method(ASUSWMI_MONITORING_GUID, 0,
+				     method_id, &input, &output);
+
+	if (ACPI_FAILURE(status))
+		return -EIO;
+
+	obj = output.pointer;
+	if (obj && obj->type == ACPI_TYPE_INTEGER)
+		tmp = obj->integer.value;
+
+	if (retval)
+		*retval = tmp;
+
+	kfree(obj);
+
+	if (tmp == ASUSWMI_UNSUPPORTED_METHOD)
+		return -ENODEV;
+	return 0;
+#else
+	return -EOPNOTSUPP;
+#endif
+}
+
+static inline int nct6775_asuswmi_write(u8 bank, u8 reg, u8 val)
+{
+	return nct6775_asuswmi_evaluate_method(ASUSWMI_METHODID_WHWM, bank,
+					      reg, val, NULL);
+}
+
+static inline int nct6775_asuswmi_read(u8 bank, u8 reg, u8 *val)
+{
+	u32 ret, tmp = 0;
+
+	ret = nct6775_asuswmi_evaluate_method(ASUSWMI_METHODID_RHWM, bank,
+					      reg, 0, &tmp);
+	*val = tmp;
+	return ret;
+}
+
+static int superio_wmi_inb(struct nct6775_sio_data *sio_data, int reg)
+{
+	int tmp = 0;
+
+	nct6775_asuswmi_evaluate_method(ASUSWMI_METHODID_RSIO, sio_data->ld,
+					reg, 0, &tmp);
+	return tmp;
+}
+
+static void superio_wmi_outb(struct nct6775_sio_data *sio_data, int reg, int val)
+{
+	nct6775_asuswmi_evaluate_method(ASUSWMI_METHODID_WSIO, sio_data->ld,
+					reg, val, NULL);
+}
+
+static void superio_wmi_select(struct nct6775_sio_data *sio_data, int ld)
+{
+	sio_data->ld = ld;
+}
+
+static int superio_wmi_enter(struct nct6775_sio_data *sio_data)
+{
+	return 0;
+}
+
+static void superio_wmi_exit(struct nct6775_sio_data *sio_data)
+{
+}
+
 static void superio_outb(struct nct6775_sio_data *sio_data, int reg, int val)
 {
 	int ioreg = sio_data->sioreg;
@@ -207,6 +296,7 @@ static void superio_exit(struct nct6775_sio_data *sio_data)
 
 #define NCT6775_REG_BANK	0x4E
 #define NCT6775_REG_CONFIG	0x40
+#define NCT6775_PORT_CHIPID	0x58
 
 /*
  * Not currently used:
@@ -1423,6 +1513,54 @@ static bool is_word_sized(struct nct6775_data *data, u16 reg)
 	return false;
 }
 
+static inline void nct6775_wmi_set_bank(struct nct6775_data *data, u16 reg)
+{
+	u8 bank = reg >> 8;
+
+	data->bank = bank;
+}
+
+static u16 nct6775_wmi_read_value(struct nct6775_data *data, u16 reg)
+{
+	int res, err, word_sized = is_word_sized(data, reg);
+	u8 tmp = 0;
+
+	nct6775_wmi_set_bank(data, reg);
+
+	err = nct6775_asuswmi_read(data->bank, reg, &tmp);
+	if (err)
+		return 0;
+
+	res = tmp;
+	if (word_sized) {
+		err = nct6775_asuswmi_read(data->bank, (reg & 0xff) + 1, &tmp);
+		if (err)
+			return 0;
+
+		res = (res << 8) + tmp;
+	}
+	return res;
+}
+
+static int nct6775_wmi_write_value(struct nct6775_data *data, u16 reg, u16 value)
+{
+	int res, word_sized = is_word_sized(data, reg);
+
+	nct6775_wmi_set_bank(data, reg);
+
+	if (word_sized) {
+		res = nct6775_asuswmi_write(data->bank, reg & 0xff, value >> 8);
+		if (res)
+			return res;
+
+		res = nct6775_asuswmi_write(data->bank, (reg & 0xff) + 1, value);
+	} else {
+		res = nct6775_asuswmi_write(data->bank, reg & 0xff, value);
+	}
+
+	return res;
+}
+
 /*
  * On older chips, only registers 0x50-0x5f are banked.
  * On more recent chips, all registers are banked.
@@ -3818,10 +3956,12 @@ static int nct6775_probe(struct platform_device *pdev)
 	struct device *hwmon_dev;
 	int num_attr_groups = 0;
 
-	res = platform_get_resource(pdev, IORESOURCE_IO, 0);
-	if (!devm_request_region(&pdev->dev, res->start, IOREGION_LENGTH,
-				 DRVNAME))
-		return -EBUSY;
+	if (sio_data->access == access_direct) {
+		res = platform_get_resource(pdev, IORESOURCE_IO, 0);
+		if (!devm_request_region(&pdev->dev, res->start, IOREGION_LENGTH,
+					 DRVNAME))
+			return -EBUSY;
+	}
 
 	data = devm_kzalloc(&pdev->dev, sizeof(struct nct6775_data),
 			    GFP_KERNEL);
@@ -3830,9 +3970,16 @@ static int nct6775_probe(struct platform_device *pdev)
 
 	data->kind = sio_data->kind;
 	data->sioreg = sio_data->sioreg;
-	data->addr = res->start;
-	data->read_value = nct6775_read_value;
-	data->write_value = nct6775_write_value;
+
+	if (sio_data->access == access_direct) {
+		data->addr = res->start;
+		data->read_value = nct6775_read_value;
+		data->write_value = nct6775_write_value;
+	} else {
+		data->read_value = nct6775_wmi_read_value;
+		data->write_value = nct6775_wmi_write_value;
+	}
+
 	mutex_init(&data->update_lock);
 	data->name = nct6775_device_names[data->kind];
 	data->bank = 0xff;		/* Force initial bank selection */
@@ -4743,6 +4890,7 @@ static int __init nct6775_find(int sioaddr, struct nct6775_sio_data *sio_data)
 	int err;
 	int addr;
 
+	sio_data->access = access_direct;
 	sio_data->sioreg = sioaddr;
 
 	err = sio_data->sio_enter(sio_data);
@@ -4837,6 +4985,23 @@ static int __init nct6775_find(int sioaddr, struct nct6775_sio_data *sio_data)
  */
 static struct platform_device *pdev[2];
 
+static const char * const asus_wmi_boards[] = {
+	"PRIME B460-PLUS",
+	"ROG CROSSHAIR VIII DARK HERO",
+	"ROG CROSSHAIR VIII HERO",
+	"ROG CROSSHAIR VIII IMPACT",
+	"ROG STRIX B550-E GAMING",
+	"ROG STRIX B550-F GAMING",
+	"ROG STRIX B550-F GAMING (WI-FI)",
+	"ROG STRIX Z490-I GAMING",
+	"TUF GAMING B550M-PLUS",
+	"TUF GAMING B550M-PLUS (WI-FI)",
+	"TUF GAMING B550-PLUS",
+	"TUF GAMING X570-PLUS",
+	"TUF GAMING X570-PLUS (WI-FI)",
+	"TUF GAMING X570-PRO (WI-FI)",
+};
+
 static int __init sensors_nct6775_init(void)
 {
 	int i, err;
@@ -4845,11 +5010,32 @@ static int __init sensors_nct6775_init(void)
 	struct resource res;
 	struct nct6775_sio_data sio_data;
 	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)
 		return err;
 
+	board_vendor = dmi_get_system_info(DMI_BOARD_VENDOR);
+	board_name = dmi_get_system_info(DMI_BOARD_NAME);
+
+	if (board_name && board_vendor &&
+	    !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)) {
+				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");
+			}
+		}
+	}
+
 	/*
 	 * initialize sio_data->kind and sio_data->sioreg.
 	 *
@@ -4870,6 +5056,16 @@ static int __init sensors_nct6775_init(void)
 
 		found = true;
 
+		sio_data.access = access;
+
+		if (access == access_asuswmi) {
+			sio_data.sio_outb = superio_wmi_outb;
+			sio_data.sio_inb = superio_wmi_inb;
+			sio_data.sio_select = superio_wmi_select;
+			sio_data.sio_enter = superio_wmi_enter;
+			sio_data.sio_exit = superio_wmi_exit;
+		}
+
 		pdev[i] = platform_device_alloc(DRVNAME, address);
 		if (!pdev[i]) {
 			err = -ENOMEM;
@@ -4881,23 +5077,25 @@ static int __init sensors_nct6775_init(void)
 		if (err)
 			goto exit_device_put;
 
-		memset(&res, 0, sizeof(res));
-		res.name = DRVNAME;
-		res.start = address + IOREGION_OFFSET;
-		res.end = address + IOREGION_OFFSET + IOREGION_LENGTH - 1;
-		res.flags = IORESOURCE_IO;
+		if (sio_data.access == access_direct) {
+			memset(&res, 0, sizeof(res));
+			res.name = DRVNAME;
+			res.start = address + IOREGION_OFFSET;
+			res.end = address + IOREGION_OFFSET + IOREGION_LENGTH - 1;
+			res.flags = IORESOURCE_IO;
+
+			err = acpi_check_resource_conflict(&res);
+			if (err) {
+				platform_device_put(pdev[i]);
+				pdev[i] = NULL;
+				continue;
+			}
 
-		err = acpi_check_resource_conflict(&res);
-		if (err) {
-			platform_device_put(pdev[i]);
-			pdev[i] = NULL;
-			continue;
+			err = platform_device_add_resources(pdev[i], &res, 1);
+			if (err)
+				goto exit_device_put;
 		}
 
-		err = platform_device_add_resources(pdev[i], &res, 1);
-		if (err)
-			goto exit_device_put;
-
 		/* platform_device_add calls probe() */
 		err = platform_device_add(pdev[i]);
 		if (err)