fpga: dfl: move dfl_device_id to mod_devicetable.h

In order to support MODULE_DEVICE_TABLE() for dfl device driver, this
patch moves struct dfl_device_id to mod_devicetable.h

Some brief description for DFL (Device Feature List) is added to make
the DFL known to the whole kernel.
Reviewed-by: Tom Rix <trix@redhat.com>
Acked-by: Wu Hao <hao.wu@intel.com>
Signed-off-by: Xu Yilun <yilun.xu@intel.com>
Signed-off-by: Wu Hao <hao.wu@intel.com>
Signed-off-by: Matthew Gerlach <matthew.gerlach@linux.intel.com>
Signed-off-by: Russ Weight <russell.h.weight@intel.com>
Signed-off-by: Moritz Fischer <mdf@kernel.org>
Link: https://lore.kernel.org/r/20210107043714.991646-5-mdf@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/fpga/dfl.h

@@ -22,6 +22,7 @@
 #include <linux/interrupt.h>
 #include <linux/iopoll.h>
 #include <linux/io-64-nonatomic-lo-hi.h>
+#include <linux/mod_devicetable.h>
 #include <linux/platform_device.h>
 #include <linux/slab.h>
 #include <linux/uuid.h>
@@ -525,18 +526,6 @@ enum dfl_id_type {
 	DFL_ID_MAX,
 };
 
-/**
- * struct dfl_device_id -  dfl device identifier
- * @type: DFL FIU type of the device. See enum dfl_id_type.
- * @feature_id: feature identifier local to its DFL FIU type.
- * @driver_data: driver specific data.
- */
-struct dfl_device_id {
-	u16 type;
-	u16 feature_id;
-	unsigned long driver_data;
-};
-
 /**
  * struct dfl_device - represent an dfl device on dfl bus
  *

include/linux/mod_devicetable.h

@@ -846,4 +846,28 @@ struct auxiliary_device_id {
 	kernel_ulong_t driver_data;
 };
 
+/*
+ * DFL (Device Feature List)
+ *
+ * DFL defines a linked list of feature headers within the device MMIO space to
+ * provide an extensible way of adding features. Software can walk through these
+ * predefined data structures to enumerate features. It is now used in the FPGA.
+ * See Documentation/fpga/dfl.rst for more information.
+ *
+ * The dfl bus type is introduced to match the individual feature devices (dfl
+ * devices) for specific dfl drivers.
+ */
+
+/**
+ * struct dfl_device_id -  dfl device identifier
+ * @type: DFL FIU type of the device. See enum dfl_id_type.
+ * @feature_id: feature identifier local to its DFL FIU type.
+ * @driver_data: driver specific data.
+ */
+struct dfl_device_id {
+	__u16 type;
+	__u16 feature_id;
+	kernel_ulong_t driver_data;
+};
+
 #endif /* LINUX_MOD_DEVICETABLE_H */