[PATCH v11 2/6] platform/x86: Add lenovo-wmi-helpers

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

Adds lenovo-wmi-helpers, which provides a common wrapper function for
wmidev_evaluate_method that does data validation and error handling.

Reviewed-by: Alok Tiwari <alok.a.tiwari@oracle.com>
Reviewed-by: Armin Wolf <W_Armin@gmx.de>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Derek J. Clark <derekjohn.clark@gmail.com>
---
v11:
 - Formatting
v10: No change
v9: Fix missing newline before return in lwmi_dev_evaluate_int
v8: No change
v7:
 - Fix typos
v6:
 - Fix typos and rewordings from v5 review.
v5:
 - Fixes from v4 review.
 - Combine all previous methods into a single function that takes a
   buffer for the wmi method arguments.
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                               |  1 +
 drivers/platform/x86/Kconfig              |  4 ++
 drivers/platform/x86/Makefile             |  1 +
 drivers/platform/x86/lenovo-wmi-helpers.c | 74 +++++++++++++++++++++++
 drivers/platform/x86/lenovo-wmi-helpers.h | 20 ++++++
 5 files changed, 100 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..aab59a777693 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -13164,6 +13164,7 @@ 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.*
 
 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..4a194aad1ed0
--- /dev/null
+++ b/drivers/platform/x86/lenovo-wmi-helpers.c
@@ -0,0 +1,74 @@
+// 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 Mode" 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 Mode" 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 from the WMI interface,
+ * enumerated here.
+ *
+ * Copyright (C) 2025 Derek J. Clark <derekjohn.clark@gmail.com>
+ */
+
+#include <linux/acpi.h>
+#include <linux/cleanup.h>
+#include <linux/errno.h>
+#include <linux/export.h>
+#include <linux/module.h>
+#include <linux/wmi.h>
+
+#include "lenovo-wmi-helpers.h"
+
+/**
+ * lwmi_dev_evaluate_int() - Helper function for calling WMI methods that
+ * return an 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.
+ *
+ * Calls wmidev_evaluate_method for Lenovo WMI devices that return an ACPI
+ * integer. Validates the return value type and assigns the value to the
+ * retval pointer.
+ *
+ * Return: 0 on success, or an error code.
+ */
+int lwmi_dev_evaluate_int(struct wmi_device *wdev, u8 instance, u32 method_id,
+			  unsigned char *buf, size_t size, u32 *retval)
+{
+	struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
+	union acpi_object *ret_obj __free(kfree) = NULL;
+	struct acpi_buffer input = { size, buf };
+	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_int, "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..20fd21749803
--- /dev/null
+++ b/drivers/platform/x86/lenovo-wmi-helpers.h
@@ -0,0 +1,20 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+/* Copyright (C) 2025 Derek J. Clark <derekjohn.clark@gmail.com> */
+
+#ifndef _LENOVO_WMI_HELPERS_H_
+#define _LENOVO_WMI_HELPERS_H_
+
+#include <linux/types.h>
+
+struct wmi_device;
+
+struct wmi_method_args_32 {
+	u32 arg0;
+	u32 arg1;
+};
+
+int lwmi_dev_evaluate_int(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