platform/x86: wmi: Add a new interface to read block data

wmi_query_block is unnecessarily indirect. Add a straightforward
method for wmi bus drivers to use to read block data.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Mario Limonciello <mario_limonciello@dell.com>
Cc: Pali Rohár <pali.rohar@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: platform-driver-x86@vger.kernel.org
Cc: linux-acpi@vger.kernel.org
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>

drivers/platform/x86/wmi.c

@@ -244,19 +244,10 @@ u32 method_id, const struct acpi_buffer *in, struct acpi_buffer *out)
 }
 EXPORT_SYMBOL_GPL(wmi_evaluate_method);
 
-/**
- * wmi_query_block - Return contents of a WMI block
- * @guid_string: 36 char string of the form fa50ff2b-f2e8-45de-83fa-65417f2f49ba
- * @instance: Instance index
- * &out: Empty buffer to return the contents of the data block to
- *
- * Return the contents of an ACPI-WMI data block to a buffer
- */
-acpi_status wmi_query_block(const char *guid_string, u8 instance,
-struct acpi_buffer *out)
+static acpi_status __query_block(struct wmi_block *wblock, u8 instance,
+				 struct acpi_buffer *out)
 {
 	struct guid_block *block = NULL;
-	struct wmi_block *wblock = NULL;
 	acpi_handle handle;
 	acpi_status status, wc_status = AE_ERROR;
 	struct acpi_object_list input;
@@ -264,12 +255,9 @@ struct acpi_buffer *out)
 	char method[5];
 	char wc_method[5] = "WC";
 
-	if (!guid_string || !out)
+	if (!out)
 		return AE_BAD_PARAMETER;
 
-	if (!find_guid(guid_string, &wblock))
-		return AE_ERROR;
-
 	block = &wblock->gblock;
 	handle = wblock->acpi_device->handle;
 
@@ -320,8 +308,42 @@ struct acpi_buffer *out)
 
 	return status;
 }
+
+/**
+ * wmi_query_block - Return contents of a WMI block (deprecated)
+ * @guid_string: 36 char string of the form fa50ff2b-f2e8-45de-83fa-65417f2f49ba
+ * @instance: Instance index
+ * &out: Empty buffer to return the contents of the data block to
+ *
+ * Return the contents of an ACPI-WMI data block to a buffer
+ */
+acpi_status wmi_query_block(const char *guid_string, u8 instance,
+			    struct acpi_buffer *out)
+{
+	struct wmi_block *wblock;
+
+	if (!guid_string)
+		return AE_BAD_PARAMETER;
+
+	if (!find_guid(guid_string, &wblock))
+		return AE_ERROR;
+
+	return __query_block(wblock, instance, out);
+}
 EXPORT_SYMBOL_GPL(wmi_query_block);
 
+union acpi_object *wmidev_block_query(struct wmi_device *wdev, u8 instance)
+{
+	struct acpi_buffer out = { ACPI_ALLOCATE_BUFFER, NULL };
+	struct wmi_block *wblock = container_of(wdev, struct wmi_block, dev);
+
+	if (ACPI_FAILURE(__query_block(wblock, instance, &out)))
+		return NULL;
+
+	return (union acpi_object *)out.pointer;
+}
+EXPORT_SYMBOL_GPL(wmidev_block_query);
+
 /**
  * wmi_set_block - Write to a WMI block
  * @guid_string: 36 char string of the form fa50ff2b-f2e8-45de-83fa-65417f2f49ba
@@ -331,7 +353,7 @@ EXPORT_SYMBOL_GPL(wmi_query_block);
  * Write the contents of the input buffer to an ACPI-WMI data block
  */
 acpi_status wmi_set_block(const char *guid_string, u8 instance,
-const struct acpi_buffer *in)
+			  const struct acpi_buffer *in)
 {
 	struct guid_block *block = NULL;
 	struct wmi_block *wblock = NULL;

include/linux/wmi.h

@@ -29,6 +29,10 @@ struct wmi_device {
 	bool readable, writeable;
 };
 
+/* Caller must kfree the result. */
+extern union acpi_object *wmidev_block_query(struct wmi_device *wdev,
+					     u8 instance);
+
 struct wmi_device_id {
 	const char *guid_string;
 };