[PATCH v4 2/6 RESEND] platform/x86: Add lenovo-wmi-helpers

["Derek J. Clark" <derekjohn.clark@gmail.com>]

Adds documentation for all new lenovo-wmi drivers.

Signed-off-by: Derek J. Clark <derekjohn.clark@gmail.com>
---
v4:
 - Changed namespace to LENOVO_WMI_HELPERS from LENOVO_WMI.
 - Changed filenames to lenovo-wmi-helpers from lenovo-wmi.
 - Removed structs and functions implemented by other drivers.
---
 MAINTAINERS                               |  2 +
 drivers/platform/x86/Kconfig              |  4 ++
 drivers/platform/x86/Makefile             |  1 +
 drivers/platform/x86/lenovo-wmi-helpers.c | 64 +++++++++++++++++++++++
 drivers/platform/x86/lenovo-wmi-helpers.h | 24 +++++++++
 5 files changed, 95 insertions(+)
 create mode 100644 drivers/platform/x86/lenovo-wmi-helpers.c
 create mode 100644 drivers/platform/x86/lenovo-wmi-helpers.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 675f4b26426d..3a370a18b806 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -13164,6 +13164,8 @@ L:	platform-driver-x86@vger.kernel.org
 S:	Maintained
 F:	Documentation/wmi/devices/lenovo-wmi-gamezone.rst
 F:	Documentation/wmi/devices/lenovo-wmi-other.rst
+F:	drivers/platform/x86/lenovo-wmi-helpers.c
+F:	drivers/platform/x86/lenovo-wmi-helpers.h
 
 LENOVO WMI HOTKEY UTILITIES DRIVER
 M:	Jackie Dong <xy-jackie@139.com>
diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
index 43407e76476b..bece1ba61417 100644
--- a/drivers/platform/x86/Kconfig
+++ b/drivers/platform/x86/Kconfig
@@ -459,6 +459,10 @@ config IBM_RTL
 	 state = 0 (BIOS SMIs on)
 	 state = 1 (BIOS SMIs off)
 
+config LENOVO_WMI_HELPERS
+	tristate
+	depends on ACPI_WMI
+
 config IDEAPAD_LAPTOP
 	tristate "Lenovo IdeaPad Laptop Extras"
 	depends on ACPI
diff --git a/drivers/platform/x86/Makefile b/drivers/platform/x86/Makefile
index 650dfbebb6c8..5a9f4e94f78b 100644
--- a/drivers/platform/x86/Makefile
+++ b/drivers/platform/x86/Makefile
@@ -69,6 +69,7 @@ obj-$(CONFIG_THINKPAD_LMI)	+= think-lmi.o
 obj-$(CONFIG_YOGABOOK)		+= lenovo-yogabook.o
 obj-$(CONFIG_YT2_1380)		+= lenovo-yoga-tab2-pro-1380-fastcharger.o
 obj-$(CONFIG_LENOVO_WMI_CAMERA)	+= lenovo-wmi-camera.o
+obj-$(CONFIG_LENOVO_WMI_HELPERS)	+= lenovo-wmi-helpers.o
 
 # Intel
 obj-y				+= intel/
diff --git a/drivers/platform/x86/lenovo-wmi-helpers.c b/drivers/platform/x86/lenovo-wmi-helpers.c
new file mode 100644
index 000000000000..36d553502223
--- /dev/null
+++ b/drivers/platform/x86/lenovo-wmi-helpers.c
@@ -0,0 +1,64 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Lenovo Legion WMI helpers driver. The Lenovo Legion WMI interface is
+ * broken up into multiple GUID interfaces that require cross-references
+ * between GUID's for some functionality. The "Custom Method" interface is a
+ * legacy interface for managing and displaying CPU & GPU power and hwmon
+ * settings and readings. The "Other Mode" interface is a modern interface
+ * that replaces or extends the "Custom Method" interface methods. The
+ * "Gamezone" interface adds advanced features such as fan profiles and
+ * overclocking. The "Lighting" interface adds control of various status
+ * lights related to different hardware components. Each of these drivers
+ * uses a common procedure to get data fro the WMI interface, enumerated here.
+ *
+ * Copyright(C) 2025 Derek J. Clark <derekjohn.clark@gmail.com>
+ *
+ */
+
+#include <linux/wmi.h>
+#include "lenovo-wmi-helpers.h"
+
+/*
+ * lwmi_dev_evaluate_method() - Helper function to call wmidev_evaluate_method
+ * for Lenovo WMI device method calls that return an ACPI integer.
+ * @wdev: Pointer to the WMI device to be called.
+ * @instance: Instance of the called method.
+ * @method_id: WMI Method ID for the method to be called.
+ * @buf: Buffer of all arguments for the given method_id.
+ * @size: Length of the buffer.
+ * @retval: Pointer for the return value to be assigned.
+ *
+ * Returns: 0, or an error.
+ */
+int lwmi_dev_evaluate_method(struct wmi_device *wdev, u8 instance,
+			     u32 method_id, unsigned char *buf, size_t size,
+			     u32 *retval)
+{
+	struct acpi_buffer input = { size, buf };
+	struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
+	union acpi_object *ret_obj __free(kfree) = NULL;
+	acpi_status status;
+
+	status = wmidev_evaluate_method(wdev, instance, method_id, &input,
+					&output);
+
+	if (ACPI_FAILURE(status))
+		return -EIO;
+
+	if (retval) {
+		ret_obj = output.pointer;
+		if (!ret_obj)
+			return -ENODATA;
+
+		if (ret_obj->type != ACPI_TYPE_INTEGER)
+			return -ENXIO;
+
+		*retval = (u32)ret_obj->integer.value;
+	}
+	return 0;
+};
+EXPORT_SYMBOL_NS_GPL(lwmi_dev_evaluate_method, "LENOVO_WMI_HELPERS");
+
+MODULE_AUTHOR("Derek J. Clark <derekjohn.clark@gmail.com>");
+MODULE_DESCRIPTION("Lenovo WMI Helpers Driver");
+MODULE_LICENSE("GPL");
diff --git a/drivers/platform/x86/lenovo-wmi-helpers.h b/drivers/platform/x86/lenovo-wmi-helpers.h
new file mode 100644
index 000000000000..7e0d7870790e
--- /dev/null
+++ b/drivers/platform/x86/lenovo-wmi-helpers.h
@@ -0,0 +1,24 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later
+ *
+ * Copyright(C) 2025 Derek J. Clark <derekjohn.clark@gmail.com>
+ *
+ */
+#include <linux/notifier.h>
+#include <linux/platform_profile.h>
+
+#ifndef _LENOVO_WMI_HELPERS_H_
+#define _LENOVO_WMI_HELPERS_H_
+
+#include <linux/types.h>
+#include <linux/wmi.h>
+
+struct wmi_method_args_32 {
+	u32 arg0;
+	u32 arg1;
+};
+
+int lwmi_dev_evaluate_method(struct wmi_device *wdev, u8 instance,
+			     u32 method_id, unsigned char *buf, size_t size,
+			     u32 *retval);
+
+#endif /* !_LENOVO_WMI_HELPERS_H_ */
-- 
2.49.0