hw/nvram/fw_cfg: Add the FW_CFG_DATA_GENERATOR interface

The FW_CFG_DATA_GENERATOR allows any object to produce
blob of data consumable by the fw_cfg device.

Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20200623172726.21040-3-philmd@redhat.com>

1 files changed, 43 insertions, 0 deletions

diff --git a/include/hw/nvram/fw_cfg.h b/include/hw/nvram/fw_cfg.h
index 25d9307018..11feae3177 100644
--- a/include/hw/nvram/fw_cfg.h
+++ b/include/hw/nvram/fw_cfg.h
@@ -9,11 +9,36 @@
 #define TYPE_FW_CFG     "fw_cfg"
 #define TYPE_FW_CFG_IO  "fw_cfg_io"
 #define TYPE_FW_CFG_MEM "fw_cfg_mem"
+#define TYPE_FW_CFG_DATA_GENERATOR_INTERFACE "fw_cfg-data-generator"
 
 #define FW_CFG(obj)     OBJECT_CHECK(FWCfgState,    (obj), TYPE_FW_CFG)
 #define FW_CFG_IO(obj)  OBJECT_CHECK(FWCfgIoState,  (obj), TYPE_FW_CFG_IO)
 #define FW_CFG_MEM(obj) OBJECT_CHECK(FWCfgMemState, (obj), TYPE_FW_CFG_MEM)
 
+#define FW_CFG_DATA_GENERATOR_CLASS(class) \
+    OBJECT_CLASS_CHECK(FWCfgDataGeneratorClass, (class), \
+                       TYPE_FW_CFG_DATA_GENERATOR_INTERFACE)
+#define FW_CFG_DATA_GENERATOR_GET_CLASS(obj) \
+    OBJECT_GET_CLASS(FWCfgDataGeneratorClass, (obj), \
+                     TYPE_FW_CFG_DATA_GENERATOR_INTERFACE)
+
+typedef struct FWCfgDataGeneratorClass {
+    /*< private >*/
+    InterfaceClass parent_class;
+    /*< public >*/
+
+    /**
+     * get_data:
+     * @obj: the object implementing this interface
+     * @errp: pointer to a NULL-initialized error object
+     *
+     * Returns: reference to a byte array containing the data.
+     * The caller should release the reference when no longer
+     * required.
+     */
+    GByteArray *(*get_data)(Object *obj, Error **errp);
+} FWCfgDataGeneratorClass;
+
 typedef struct fw_cfg_file FWCfgFile;
 
 #define FW_CFG_ORDER_OVERRIDE_VGA    70
@@ -263,6 +288,24 @@ void fw_cfg_add_file_callback(FWCfgState *s, const char *filename,
 void *fw_cfg_modify_file(FWCfgState *s, const char *filename, void *data,
                          size_t len);
 
+/**
+ * fw_cfg_add_from_generator:
+ * @s: fw_cfg device being modified
+ * @filename: name of new fw_cfg file item
+ * @gen_id: name of object implementing FW_CFG_DATA_GENERATOR interface
+ * @errp: pointer to a NULL initialized error object
+ *
+ * Add a new NAMED fw_cfg item with the content generated from the
+ * @gen_id object. The data generated by the @gen_id object is copied
+ * into the data structure of the fw_cfg device.
+ * The next available (unused) selector key starting at FW_CFG_FILE_FIRST
+ * will be used; also, a new entry will be added to the file directory
+ * structure residing at key value FW_CFG_FILE_DIR, containing the item name,
+ * data size, and assigned selector key value.
+ */
+void fw_cfg_add_from_generator(FWCfgState *s, const char *filename,
+                               const char *gen_id, Error **errp);
+
 FWCfgState *fw_cfg_init_io_dma(uint32_t iobase, uint32_t dma_iobase,
                                 AddressSpace *dma_as);
 FWCfgState *fw_cfg_init_io(uint32_t iobase);