[PATCH 3/3] hwmon: (nct6775) Support access via Asus WMI (v2)

[Denis Pauk <pauk.denis@gmail.com>]

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.

v2: split changes to separate patches
    limit WMI usage by DMI_BOARD_NAME in checked ASUS motherboards

Link: https://bugzilla.kernel.org/show_bug.cgi?id=204807
Signed-off-by: Bernhard Seibold <mail@bernhard-seibold.de>
Signed-off-by: Denis Pauk <pauk.denis@gmail.com>
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>
---
 drivers/hwmon/nct6775.c | 219 ++++++++++++++++++++++++++++++++++++----
 1 file changed, 198 insertions(+), 21 deletions(-)

diff --git a/drivers/hwmon/nct6775.c b/drivers/hwmon/nct6775.c
index 908521ce2ee8..ae0344811821 100644
--- a/drivers/hwmon/nct6775.c
+++ b/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;
 	void (*outb)(struct nct6775_sio_data *sio_data, int reg, int val);
 	int (*inb)(struct nct6775_sio_data *sio_data, int reg);
 	void (*select)(struct nct6775_sio_data *sio_data, int ld);
@@ -143,6 +147,92 @@ struct nct6775_sio_data {
 	void (*exit)(struct nct6775_sio_data *sio_data);
 };
 
+#define ASUSWMI_MGMT2_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 asuswmi_evaluate_method(u32 method_id,
+		u8 bank, u8 reg, u8 val, u32 *retval)
+{
+	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 = 0;
+
+	status = wmi_evaluate_method(ASUSWMI_MGMT2_GUID, 0, method_id,
+				     &input, &output);
+
+	if (ACPI_FAILURE(status))
+		return -EIO;
+
+	obj = (union acpi_object *)output.pointer;
+	if (obj && obj->type == ACPI_TYPE_INTEGER)
+		tmp = (u32) obj->integer.value;
+
+	if (retval)
+		*retval = tmp;
+
+	kfree(obj);
+
+	if (tmp == ASUSWMI_UNSUPPORTED_METHOD)
+		return -ENODEV;
+	return 0;
+}
+
+static inline int
+nct6775_asuswmi_write(u8 bank, u8 reg, u8 val)
+{
+	return asuswmi_evaluate_method(ASUSWMI_METHODID_WHWM, bank, reg, val, 0);
+}
+
+static inline int
+nct6775_asuswmi_read(u8 bank, u8 reg, u8 *val)
+{
+	u32 tmp;
+	int ret = asuswmi_evaluate_method(ASUSWMI_METHODID_RHWM, bank, reg, 0, &tmp);
+	*val = tmp & 0xff;
+	return ret;
+}
+
+static int
+superio_wmi_inb(struct nct6775_sio_data *sio_data, int reg)
+{
+	int tmp;
+
+	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)
+{
+	asuswmi_evaluate_method(ASUSWMI_METHODID_WSIO,
+			sio_data->ld, reg, val, 0);
+}
+
+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)
 {
@@ -1090,6 +1180,7 @@ struct nct6775_data {
 	int addr;	/* IO base of hw monitor block */
 	int sioreg;	/* SIO register address */
 	enum kinds kind;
+	enum sensor_access access;
 	const char *name;
 
 	const struct attribute_group *groups[6];
@@ -1432,6 +1523,11 @@ static inline void nct6775_set_bank(struct nct6775_data *data, u16 reg)
 {
 	u8 bank = reg >> 8;
 
+	if (data->access == access_asuswmi) {
+		data->bank = bank;
+		return;
+	}
+
 	if (data->bank != bank) {
 		outb_p(NCT6775_REG_BANK, data->addr + ADDR_REG_OFFSET);
 		outb_p(bank, data->addr + DATA_REG_OFFSET);
@@ -1442,8 +1538,21 @@ static inline void nct6775_set_bank(struct nct6775_data *data, u16 reg)
 static u16 nct6775_read_value(struct nct6775_data *data, u16 reg)
 {
 	int res, word_sized = is_word_sized(data, reg);
+	u8 tmp;
 
 	nct6775_set_bank(data, reg);
+
+	if (data->access == access_asuswmi) {
+		nct6775_asuswmi_read(data->bank, reg, &tmp);
+		res = (tmp & 0xff);
+		if (word_sized) {
+			nct6775_asuswmi_read(data->bank,
+					(reg & 0xff) + 1, &tmp);
+			res = (res << 8) + (tmp & 0xff);
+		}
+		return res;
+	}
+
 	outb_p(reg & 0xff, data->addr + ADDR_REG_OFFSET);
 	res = inb_p(data->addr + DATA_REG_OFFSET);
 	if (word_sized) {
@@ -1459,6 +1568,21 @@ static int nct6775_write_value(struct nct6775_data *data, u16 reg, u16 value)
 	int word_sized = is_word_sized(data, reg);
 
 	nct6775_set_bank(data, reg);
+
+	if (data->access == access_asuswmi) {
+		if (word_sized) {
+			nct6775_asuswmi_write(data->bank, (reg & 0xff),
+					(value >> 8) & 0xff);
+			nct6775_asuswmi_write(data->bank, (reg & 0xff) + 1,
+					value & 0xff);
+		} else {
+			nct6775_asuswmi_write(data->bank, (reg & 0xff),
+					value);
+		}
+
+		return 0;
+	}
+
 	outb_p(reg & 0xff, data->addr + ADDR_REG_OFFSET);
 	if (word_sized) {
 		outb_p(value >> 8, data->addr + DATA_REG_OFFSET);
@@ -3821,13 +3945,15 @@ 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 (!res)
-		return -EBUSY;
+	if (sio_data->access == access_direct) {
+		res = platform_get_resource(pdev, IORESOURCE_IO, 0);
+		if (!res)
+			return -EBUSY;
 
-	if (!devm_request_region(&pdev->dev, res->start, IOREGION_LENGTH,
-				 DRVNAME))
-		return -EBUSY;
+		if (!devm_request_region(&pdev->dev, res->start, IOREGION_LENGTH,
+					 DRVNAME))
+			return -EBUSY;
+	}
 
 	data = devm_kzalloc(&pdev->dev, sizeof(struct nct6775_data),
 			    GFP_KERNEL);
@@ -3836,7 +3962,11 @@ static int nct6775_probe(struct platform_device *pdev)
 
 	data->kind = sio_data->kind;
 	data->sioreg = sio_data->sioreg;
-	data->addr = res->start;
+	data->access = sio_data->access;
+	if (sio_data->access == access_direct)
+		data->addr = res->start;
+	else
+		data->addr = 0;
 	mutex_init(&data->update_lock);
 	data->name = nct6775_device_names[data->kind];
 	data->bank = 0xff;		/* Force initial bank selection */
@@ -4747,6 +4877,7 @@ 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->enter(sio_data);
@@ -4841,6 +4972,21 @@ static int __init nct6775_find(int sioaddr, struct nct6775_sio_data *sio_data)
  */
 static struct platform_device *pdev[2];
 
+#define NCT6775_REG_CHIPID 0x58
+
+static const char * const asus_wmi_boards[] = {
+	"PRIME B460-PLUS",
+	"ROG CROSSHAIR VIII IMPACT",
+	"ROG STRIX B550-E 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)"
+};
+
 static int __init sensors_nct6775_init(void)
 {
 	int i, err;
@@ -4849,11 +4995,29 @@ static int __init sensors_nct6775_init(void)
 	struct resource res;
 	struct nct6775_sio_data sio_data;
 	int sioaddr[2] = { 0x2e, 0x4e };
+	const char *board_vendor, *board_name;
+	enum sensor_access access = access_direct;
+	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.")) {
+		if (match_string(asus_wmi_boards,
+				ARRAY_SIZE(asus_wmi_boards), board_name) != -EINVAL) {
+			/* if reading chip id via WMI succeeds, use WMI */
+			if (!nct6775_asuswmi_read(0, NCT6775_REG_CHIPID, &tmp)) {
+				pr_info("Using Asus WMI to access chip\n");
+				access = access_asuswmi;
+			}
+		}
+	}
+
 	/*
 	 * initialize sio_data->kind and sio_data->sioreg.
 	 *
@@ -4874,6 +5038,17 @@ static int __init sensors_nct6775_init(void)
 
 		found = true;
 
+		/* Update access method */
+		sio_data.access = access;
+
+		if (access == access_asuswmi) {
+			sio_data.outb = superio_wmi_outb;
+			sio_data.inb = superio_wmi_inb;
+			sio_data.select = superio_wmi_select;
+			sio_data.enter = superio_wmi_enter;
+			sio_data.exit = superio_wmi_exit;
+		}
+
 		pdev[i] = platform_device_alloc(DRVNAME, address);
 		if (!pdev[i]) {
 			err = -ENOMEM;
@@ -4885,23 +5060,25 @@ 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)
-- 
2.33.0