started implementing lseek

src/drivers/elphel/x393_videomem.h

@@ -38,3 +38,5 @@ int frames_in_buffer_minus_one (int num_sensor);
 void memchan_enable            (int chn, int enable);
 void set_memchannel_priority   (int chn, u16 priority);
 u16 get_memchannel_priority    (int chn);
+
+loff_t videomem_lseek (struct file * file, loff_t offset, int orig);

src/include/uapi/elphel/c313a.h

@@ -1552,6 +1552,9 @@ struct p_names_t {
 
 #define      LSEEK_FSDRAM_RESET   0x01 // re-program FSDRAM (to be programmed again when accessed)
 
+// Videomem/raw image commands
+#define      LSEEK_VIDEOMEM_START 0x10 // setup and start membridge transfer
+
 #define      JPEG_CTRL_MONOCHROME    0x400
 #define      JPEG_CTRL_MONOCHROME_BLOCKED    0x1000
 #define      JPEG_CTRL_NOMOSAIC    0x1000