platform/x86: wmi: Add MSI WMI Platform driver

Add a new driver for the MSI WMI Platform interface. The underlying
ACPI WMI interface supports many features, but so far only reading
of fan speed sensors is implemented.

The driver was reverse-engineered based on a user request to the
lm-sensors project, see the github issue for details.

The ACPI WMI interface used by this driver seems to use the same
embedded controller interface as the msi-ec driver, but supports
automatic discovery of supported machines without relying on a
DMI whitelist.

The driver was tested by the user who created the github issue.

Closes: https://github.com/lm-sensors/lm-sensors/issues/475
Signed-off-by: Armin Wolf <W_Armin@gmx.de>
Link: https://lore.kernel.org/r/20240421191145.3189-1-W_Armin@gmx.de
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

3 files changed, 440 insertions, 0 deletions

diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
index 168b57df0a6a..b744f18bbfa7 100644
--- a/drivers/platform/x86/Kconfig
+++ b/drivers/platform/x86/Kconfig
@@ -698,6 +698,17 @@ config MSI_WMI
 	 To compile this driver as a module, choose M here: the module will
 	 be called msi-wmi.
 
+config MSI_WMI_PLATFORM
+	tristate "MSI WMI Platform features"
+	depends on ACPI_WMI
+	depends on HWMON
+	help
+	  Say Y here if you want to have support for WMI-based platform features
+	  like fan sensor access on MSI machines.
+
+	  To compile this driver as a module, choose M here: the module will
+	  be called msi-wmi-platform.
+
 config XO15_EBOOK
 	tristate "OLPC XO-1.5 ebook switch"
 	depends on OLPC || COMPILE_TEST
diff --git a/drivers/platform/x86/Makefile b/drivers/platform/x86/Makefile
index 8076bf3a7e83..26b8af55738b 100644
--- a/drivers/platform/x86/Makefile
+++ b/drivers/platform/x86/Makefile
@@ -78,6 +78,7 @@ obj-$(CONFIG_ACPI_QUICKSTART)  += quickstart.o
 obj-$(CONFIG_MSI_EC)		+= msi-ec.o
 obj-$(CONFIG_MSI_LAPTOP)	+= msi-laptop.o
 obj-$(CONFIG_MSI_WMI)		+= msi-wmi.o
+obj-$(CONFIG_MSI_WMI_PLATFORM)	+= msi-wmi-platform.o
 
 # OLPC
 obj-$(CONFIG_XO15_EBOOK)	+= xo15-ebook.o
diff --git a/drivers/platform/x86/msi-wmi-platform.c b/drivers/platform/x86/msi-wmi-platform.c
new file mode 100644
index 000000000000..436fb91a47db
--- /dev/null
+++ b/drivers/platform/x86/msi-wmi-platform.c
@@ -0,0 +1,428 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Linux driver for WMI platform features on MSI notebooks.
+ *
+ * Copyright (C) 2024 Armin Wolf <W_Armin@gmx.de>
+ */
+
+#define pr_format(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/acpi.h>
+#include <linux/bits.h>
+#include <linux/bitfield.h>
+#include <linux/debugfs.h>
+#include <linux/device.h>
+#include <linux/device/driver.h>
+#include <linux/errno.h>
+#include <linux/hwmon.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/printk.h>
+#include <linux/rwsem.h>
+#include <linux/types.h>
+#include <linux/wmi.h>
+
+#include <asm/unaligned.h>
+
+#define DRIVER_NAME	"msi-wmi-platform"
+
+#define MSI_PLATFORM_GUID	"ABBC0F6E-8EA1-11d1-00A0-C90629100000"
+
+#define MSI_WMI_PLATFORM_INTERFACE_VERSION	2
+
+#define MSI_PLATFORM_WMI_MAJOR_OFFSET	1
+#define MSI_PLATFORM_WMI_MINOR_OFFSET	2
+
+#define MSI_PLATFORM_EC_FLAGS_OFFSET	1
+#define MSI_PLATFORM_EC_MINOR_MASK	GENMASK(3, 0)
+#define MSI_PLATFORM_EC_MAJOR_MASK	GENMASK(5, 4)
+#define MSI_PLATFORM_EC_CHANGED_PAGE	BIT(6)
+#define MSI_PLATFORM_EC_IS_TIGERLAKE	BIT(7)
+#define MSI_PLATFORM_EC_VERSION_OFFSET	2
+
+static bool force;
+module_param_unsafe(force, bool, 0);
+MODULE_PARM_DESC(force, "Force loading without checking for supported WMI interface versions");
+
+enum msi_wmi_platform_method {
+	MSI_PLATFORM_GET_PACKAGE	= 0x01,
+	MSI_PLATFORM_SET_PACKAGE	= 0x02,
+	MSI_PLATFORM_GET_EC		= 0x03,
+	MSI_PLATFORM_SET_EC		= 0x04,
+	MSI_PLATFORM_GET_BIOS		= 0x05,
+	MSI_PLATFORM_SET_BIOS		= 0x06,
+	MSI_PLATFORM_GET_SMBUS		= 0x07,
+	MSI_PLATFORM_SET_SMBUS		= 0x08,
+	MSI_PLATFORM_GET_MASTER_BATTERY = 0x09,
+	MSI_PLATFORM_SET_MASTER_BATTERY = 0x0a,
+	MSI_PLATFORM_GET_SLAVE_BATTERY	= 0x0b,
+	MSI_PLATFORM_SET_SLAVE_BATTERY	= 0x0c,
+	MSI_PLATFORM_GET_TEMPERATURE	= 0x0d,
+	MSI_PLATFORM_SET_TEMPERATURE	= 0x0e,
+	MSI_PLATFORM_GET_THERMAL	= 0x0f,
+	MSI_PLATFORM_SET_THERMAL	= 0x10,
+	MSI_PLATFORM_GET_FAN		= 0x11,
+	MSI_PLATFORM_SET_FAN		= 0x12,
+	MSI_PLATFORM_GET_DEVICE		= 0x13,
+	MSI_PLATFORM_SET_DEVICE		= 0x14,
+	MSI_PLATFORM_GET_POWER		= 0x15,
+	MSI_PLATFORM_SET_POWER		= 0x16,
+	MSI_PLATFORM_GET_DEBUG		= 0x17,
+	MSI_PLATFORM_SET_DEBUG		= 0x18,
+	MSI_PLATFORM_GET_AP		= 0x19,
+	MSI_PLATFORM_SET_AP		= 0x1a,
+	MSI_PLATFORM_GET_DATA		= 0x1b,
+	MSI_PLATFORM_SET_DATA		= 0x1c,
+	MSI_PLATFORM_GET_WMI		= 0x1d,
+};
+
+struct msi_wmi_platform_debugfs_data {
+	struct wmi_device *wdev;
+	enum msi_wmi_platform_method method;
+	struct rw_semaphore buffer_lock;	/* Protects debugfs buffer */
+	size_t length;
+	u8 buffer[32];
+};
+
+static const char * const msi_wmi_platform_debugfs_names[] = {
+	"get_package",
+	"set_package",
+	"get_ec",
+	"set_ec",
+	"get_bios",
+	"set_bios",
+	"get_smbus",
+	"set_smbus",
+	"get_master_battery",
+	"set_master_battery",
+	"get_slave_battery",
+	"set_slave_battery",
+	"get_temperature",
+	"set_temperature",
+	"get_thermal",
+	"set_thermal",
+	"get_fan",
+	"set_fan",
+	"get_device",
+	"set_device",
+	"get_power",
+	"set_power",
+	"get_debug",
+	"set_debug",
+	"get_ap",
+	"set_ap",
+	"get_data",
+	"set_data",
+	"get_wmi"
+};
+
+static int msi_wmi_platform_parse_buffer(union acpi_object *obj, u8 *output, size_t length)
+{
+	if (obj->type != ACPI_TYPE_BUFFER)
+		return -ENOMSG;
+
+	if (obj->buffer.length != length)
+		return -EPROTO;
+
+	if (!obj->buffer.pointer[0])
+		return -EIO;
+
+	memcpy(output, obj->buffer.pointer, obj->buffer.length);
+
+	return 0;
+}
+
+static int msi_wmi_platform_query(struct wmi_device *wdev, enum msi_wmi_platform_method method,
+				  u8 *input, size_t input_length, u8 *output, size_t output_length)
+{
+	struct acpi_buffer out = { ACPI_ALLOCATE_BUFFER, NULL };
+	struct acpi_buffer in = {
+		.length = input_length,
+		.pointer = input
+	};
+	union acpi_object *obj;
+	acpi_status status;
+	int ret;
+
+	if (!input_length || !output_length)
+		return -EINVAL;
+
+	status = wmidev_evaluate_method(wdev, 0x0, method, &in, &out);
+	if (ACPI_FAILURE(status))
+		return -EIO;
+
+	obj = out.pointer;
+	if (!obj)
+		return -ENODATA;
+
+	ret = msi_wmi_platform_parse_buffer(obj, output, output_length);
+	kfree(obj);
+
+	return ret;
+}
+
+static umode_t msi_wmi_platform_is_visible(const void *drvdata, enum hwmon_sensor_types type,
+					   u32 attr, int channel)
+{
+	return 0444;
+}
+
+static int msi_wmi_platform_read(struct device *dev, enum hwmon_sensor_types type, u32 attr,
+				 int channel, long *val)
+{
+	struct wmi_device *wdev = dev_get_drvdata(dev);
+	u8 input[32] = { 0 };
+	u8 output[32];
+	u16 data;
+	int ret;
+
+	ret = msi_wmi_platform_query(wdev, MSI_PLATFORM_GET_FAN, input, sizeof(input), output,
+				     sizeof(output));
+	if (ret < 0)
+		return ret;
+
+	data = get_unaligned_be16(&output[channel * 2 + 1]);
+	if (!data)
+		*val = 0;
+	else
+		*val = 480000 / data;
+
+	return 0;
+}
+
+static const struct hwmon_ops msi_wmi_platform_ops = {
+	.is_visible = msi_wmi_platform_is_visible,
+	.read = msi_wmi_platform_read,
+};
+
+static const struct hwmon_channel_info * const msi_wmi_platform_info[] = {
+	HWMON_CHANNEL_INFO(fan,
+			   HWMON_F_INPUT,
+			   HWMON_F_INPUT,
+			   HWMON_F_INPUT,
+			   HWMON_F_INPUT
+			   ),
+	NULL
+};
+
+static const struct hwmon_chip_info msi_wmi_platform_chip_info = {
+	.ops = &msi_wmi_platform_ops,
+	.info = msi_wmi_platform_info,
+};
+
+static ssize_t msi_wmi_platform_write(struct file *fp, const char __user *input, size_t length,
+				      loff_t *offset)
+{
+	struct seq_file *seq = fp->private_data;
+	struct msi_wmi_platform_debugfs_data *data = seq->private;
+	u8 payload[32] = { };
+	ssize_t ret;
+
+	/* Do not allow partial writes */
+	if (*offset != 0)
+		return -EINVAL;
+
+	/* Do not allow incomplete command buffers */
+	if (length != data->length)
+		return -EINVAL;
+
+	ret = simple_write_to_buffer(payload, sizeof(payload), offset, input, length);
+	if (ret < 0)
+		return ret;
+
+	down_write(&data->buffer_lock);
+	ret = msi_wmi_platform_query(data->wdev, data->method, payload, data->length, data->buffer,
+				     data->length);
+	up_write(&data->buffer_lock);
+
+	if (ret < 0)
+		return ret;
+
+	return length;
+}
+
+static int msi_wmi_platform_show(struct seq_file *seq, void *p)
+{
+	struct msi_wmi_platform_debugfs_data *data = seq->private;
+	int ret;
+
+	down_read(&data->buffer_lock);
+	ret = seq_write(seq, data->buffer, data->length);
+	up_read(&data->buffer_lock);
+
+	return ret;
+}
+
+static int msi_wmi_platform_open(struct inode *inode, struct file *fp)
+{
+	struct msi_wmi_platform_debugfs_data *data = inode->i_private;
+
+	/* The seq_file uses the last byte of the buffer for detecting buffer overflows */
+	return single_open_size(fp, msi_wmi_platform_show, data, data->length + 1);
+}
+
+static const struct file_operations msi_wmi_platform_debugfs_fops = {
+	.owner = THIS_MODULE,
+	.open = msi_wmi_platform_open,
+	.read = seq_read,
+	.write = msi_wmi_platform_write,
+	.llseek = seq_lseek,
+	.release = single_release,
+};
+
+static void msi_wmi_platform_debugfs_remove(void *data)
+{
+	struct dentry *dir = data;
+
+	debugfs_remove_recursive(dir);
+}
+
+static void msi_wmi_platform_debugfs_add(struct wmi_device *wdev, struct dentry *dir,
+					 const char *name, enum msi_wmi_platform_method method)
+{
+	struct msi_wmi_platform_debugfs_data *data;
+	struct dentry *entry;
+
+	data = devm_kzalloc(&wdev->dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return;
+
+	data->wdev = wdev;
+	data->method = method;
+	init_rwsem(&data->buffer_lock);
+
+	/* The ACPI firmware for now always requires a 32 byte input buffer due to
+	 * a peculiarity in how Windows handles the CreateByteField() ACPI operator.
+	 */
+	data->length = 32;
+
+	entry = debugfs_create_file(name, 0600, dir, data, &msi_wmi_platform_debugfs_fops);
+	if (IS_ERR(entry))
+		devm_kfree(&wdev->dev, data);
+}
+
+static void msi_wmi_platform_debugfs_init(struct wmi_device *wdev)
+{
+	struct dentry *dir;
+	char dir_name[64];
+	int ret, method;
+
+	scnprintf(dir_name, ARRAY_SIZE(dir_name), "%s-%s", DRIVER_NAME, dev_name(&wdev->dev));
+
+	dir = debugfs_create_dir(dir_name, NULL);
+	if (IS_ERR(dir))
+		return;
+
+	ret = devm_add_action_or_reset(&wdev->dev, msi_wmi_platform_debugfs_remove, dir);
+	if (ret < 0)
+		return;
+
+	for (method = MSI_PLATFORM_GET_PACKAGE; method <= MSI_PLATFORM_GET_WMI; method++)
+		msi_wmi_platform_debugfs_add(wdev, dir, msi_wmi_platform_debugfs_names[method - 1],
+					     method);
+}
+
+static int msi_wmi_platform_hwmon_init(struct wmi_device *wdev)
+{
+	struct device *hdev;
+
+	hdev = devm_hwmon_device_register_with_info(&wdev->dev, "msi_wmi_platform", wdev,
+						    &msi_wmi_platform_chip_info, NULL);
+
+	return PTR_ERR_OR_ZERO(hdev);
+}
+
+static int msi_wmi_platform_ec_init(struct wmi_device *wdev)
+{
+	u8 input[32] = { 0 };
+	u8 output[32];
+	u8 flags;
+	int ret;
+
+	ret = msi_wmi_platform_query(wdev, MSI_PLATFORM_GET_EC, input, sizeof(input), output,
+				     sizeof(output));
+	if (ret < 0)
+		return ret;
+
+	flags = output[MSI_PLATFORM_EC_FLAGS_OFFSET];
+
+	dev_dbg(&wdev->dev, "EC RAM version %lu.%lu\n",
+		FIELD_GET(MSI_PLATFORM_EC_MAJOR_MASK, flags),
+		FIELD_GET(MSI_PLATFORM_EC_MINOR_MASK, flags));
+	dev_dbg(&wdev->dev, "EC firmware version %.28s\n",
+		&output[MSI_PLATFORM_EC_VERSION_OFFSET]);
+
+	if (!(flags & MSI_PLATFORM_EC_IS_TIGERLAKE)) {
+		if (!force)
+			return -ENODEV;
+
+		dev_warn(&wdev->dev, "Loading on a non-Tigerlake platform\n");
+	}
+
+	return 0;
+}
+
+static int msi_wmi_platform_init(struct wmi_device *wdev)
+{
+	u8 input[32] = { 0 };
+	u8 output[32];
+	int ret;
+
+	ret = msi_wmi_platform_query(wdev, MSI_PLATFORM_GET_WMI, input, sizeof(input), output,
+				     sizeof(output));
+	if (ret < 0)
+		return ret;
+
+	dev_dbg(&wdev->dev, "WMI interface version %u.%u\n",
+		output[MSI_PLATFORM_WMI_MAJOR_OFFSET],
+		output[MSI_PLATFORM_WMI_MINOR_OFFSET]);
+
+	if (output[MSI_PLATFORM_WMI_MAJOR_OFFSET] != MSI_WMI_PLATFORM_INTERFACE_VERSION) {
+		if (!force)
+			return -ENODEV;
+
+		dev_warn(&wdev->dev, "Loading despite unsupported WMI interface version (%u.%u)\n",
+			 output[MSI_PLATFORM_WMI_MAJOR_OFFSET],
+			 output[MSI_PLATFORM_WMI_MINOR_OFFSET]);
+	}
+
+	return 0;
+}
+
+static int msi_wmi_platform_probe(struct wmi_device *wdev, const void *context)
+{
+	int ret;
+
+	ret = msi_wmi_platform_init(wdev);
+	if (ret < 0)
+		return ret;
+
+	ret = msi_wmi_platform_ec_init(wdev);
+	if (ret < 0)
+		return ret;
+
+	msi_wmi_platform_debugfs_init(wdev);
+
+	return msi_wmi_platform_hwmon_init(wdev);
+}
+
+static const struct wmi_device_id msi_wmi_platform_id_table[] = {
+	{ MSI_PLATFORM_GUID, NULL },
+	{ }
+};
+MODULE_DEVICE_TABLE(wmi, msi_wmi_platform_id_table);
+
+static struct wmi_driver msi_wmi_platform_driver = {
+	.driver = {
+		.name = DRIVER_NAME,
+		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
+	},
+	.id_table = msi_wmi_platform_id_table,
+	.probe = msi_wmi_platform_probe,
+	.no_singleton = true,
+};
+module_wmi_driver(msi_wmi_platform_driver);
+
+MODULE_AUTHOR("Armin Wolf <W_Armin@gmx.de>");
+MODULE_DESCRIPTION("MSI WMI platform features");
+MODULE_LICENSE("GPL");