[PATCH 1/6] platform/wmi: Add wmidev_invoke_procedure()

[Armin Wolf <W_Armin@gmx.de>]

Some WMI methods return no values, so the whole postprocessing
of the result data is not needed for them. Add a special function
for calling such WMI methods to prepare for future changes of
the main wmidev_invoke_method() function.

Signed-off-by: Armin Wolf <W_Armin@gmx.de>
---
 .../wmi/driver-development-guide.rst          |  3 +-
 drivers/platform/wmi/core.c                   | 44 +++++++++++++++++++
 include/linux/wmi.h                           |  3 ++
 3 files changed, 49 insertions(+), 1 deletion(-)

diff --git a/Documentation/wmi/driver-development-guide.rst b/Documentation/wmi/driver-development-guide.rst
index fbc2d9b12fe9..5b94402874c4 100644
--- a/Documentation/wmi/driver-development-guide.rst
+++ b/Documentation/wmi/driver-development-guide.rst
@@ -106,7 +106,8 @@ WMI method drivers
 
 WMI drivers can call WMI device methods using wmidev_invoke_method(). For each WMI method
 invocation the WMI driver needs to provide the instance number and the method ID, as well as
-a buffer with the method arguments and optionally a buffer for the results.
+a buffer with the method arguments and optionally a buffer for the results. When calling WMI
+methods that do not return any values, wmidev_invoke_procedure() should be used instead.
 
 The layout of said buffers is device-specific and described by the Binary MOF data associated
 with a given WMI device. Said Binary MOF data also describes the method ID of a given WMI method
diff --git a/drivers/platform/wmi/core.c b/drivers/platform/wmi/core.c
index b8e6b9a421c6..7cc5ca11a60d 100644
--- a/drivers/platform/wmi/core.c
+++ b/drivers/platform/wmi/core.c
@@ -427,6 +427,50 @@ int wmidev_invoke_method(struct wmi_device *wdev, u8 instance, u32 method_id,
 }
 EXPORT_SYMBOL_GPL(wmidev_invoke_method);
 
+/**
+ * wmidev_invoke_procedure - Invoke a WMI method that does not return values
+ * @wdev: A wmi bus device from a driver
+ * @instance: Instance index
+ * @method_id: Method ID to call
+ * @in: Mandatory WMI buffer containing input for the method call
+ *
+ * Invoke a WMI method that does not return any values. Use wmidev_invoke_method()
+ * for WMI methods that do return values.
+ *
+ * Return: 0 on success or negative error code on failure.
+ */
+int wmidev_invoke_procedure(struct wmi_device *wdev, u8 instance, u32 method_id,
+			    const struct wmi_buffer *in)
+{
+	struct wmi_block *wblock = container_of(wdev, struct wmi_block, dev);
+	struct acpi_buffer ain;
+	acpi_status status;
+	int ret;
+
+	if (wblock->gblock.flags & ACPI_WMI_STRING) {
+		ret = wmi_marshal_string(in, &ain);
+		if (ret < 0)
+			return ret;
+	} else {
+		if (in->length > U32_MAX)
+			return -E2BIG;
+
+		ain.length = in->length;
+		ain.pointer = in->data;
+	}
+
+	status = wmidev_evaluate_method(wdev, instance, method_id, &ain, NULL);
+
+	if (wblock->gblock.flags & ACPI_WMI_STRING)
+		kfree(ain.pointer);
+
+	if (ACPI_FAILURE(status))
+		return -EIO;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(wmidev_invoke_procedure);
+
 static acpi_status __query_block(struct wmi_block *wblock, u8 instance,
 				 struct acpi_buffer *out)
 {
diff --git a/include/linux/wmi.h b/include/linux/wmi.h
index 75cb0c7cfe57..b00950dc1231 100644
--- a/include/linux/wmi.h
+++ b/include/linux/wmi.h
@@ -70,6 +70,9 @@ ssize_t wmi_string_from_utf8s(struct wmi_string *str, size_t max_chars, const u8
 int wmidev_invoke_method(struct wmi_device *wdev, u8 instance, u32 method_id,
 			 const struct wmi_buffer *in, struct wmi_buffer *out);
 
+int wmidev_invoke_procedure(struct wmi_device *wdev, u8 instance, u32 method_id,
+			    const struct wmi_buffer *in);
+
 int wmidev_query_block(struct wmi_device *wdev, u8 instance, struct wmi_buffer *out);
 
 int wmidev_set_block(struct wmi_device *wdev, u8 instance, const struct wmi_buffer *in);
-- 
2.39.5