fw_cfg: add write callback

Reintroduce the write callback that was removed when write support was
removed in commit 023e3148567ac898c7258138f8e86c3c2bb40d07.

Contrary to the previous callback implementation, the write_cb
callback is called whenever a write happened, so handlers must be
ready to handle partial write as necessary.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/include/hw/nvram/fw_cfg.h b/include/hw/nvram/fw_cfg.h
index f50d068563..7ccbae5fba 100644
--- a/include/hw/nvram/fw_cfg.h
+++ b/include/hw/nvram/fw_cfg.h
@@ -45,6 +45,7 @@ typedef struct FWCfgDmaAccess {
 } QEMU_PACKED FWCfgDmaAccess;
 
 typedef void (*FWCfgCallback)(void *opaque);
+typedef void (*FWCfgWriteCallback)(void *opaque, off_t start, size_t len);
 
 struct FWCfgState {
     /*< private >*/
@@ -183,6 +184,7 @@ void fw_cfg_add_file(FWCfgState *s, const char *filename, void *data,
  * @s: fw_cfg device being modified
  * @filename: name of new fw_cfg file item
  * @select_cb: callback function when selecting
+ * @write_cb: callback function after a write
  * @callback_opaque: argument to be passed into callback function
  * @data: pointer to start of item data
  * @len: size of item data
@@ -202,6 +204,7 @@ void fw_cfg_add_file(FWCfgState *s, const char *filename, void *data,
  */
 void fw_cfg_add_file_callback(FWCfgState *s, const char *filename,
                               FWCfgCallback select_cb,
+                              FWCfgWriteCallback write_cb,
                               void *callback_opaque,
                               void *data, size_t len, bool read_only);