spl: Introduce new function spl_board_prepare_for_boot

Call this function before passing control from SPL.
For fpga case it is necessary to enable for example level shifters
when bitstream is programmed.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

common/spl/spl.c

@@ -64,6 +64,11 @@ __weak void spl_board_prepare_for_linux(void)
 	/* Nothing to do! */
 }
 
+__weak void spl_board_prepare_for_boot(void)
+{
+	/* Nothing to do! */
+}
+
 void spl_set_header_raw_uboot(void)
 {
 	spl_image.size = CONFIG_SYS_MONITOR_LEN;
@@ -404,6 +409,7 @@ void board_init_r(gd_t *dummy1, ulong dummy2)
 #endif
 
 	debug("loaded - jumping to U-Boot...");
+	spl_board_prepare_for_boot();
 	jump_to_image_no_args(&spl_image);
 }
 

include/spl.h

@@ -58,6 +58,7 @@ u32 spl_boot_mode(void);
 void spl_set_header_raw_uboot(void);
 int spl_parse_image_header(const struct image_header *header);
 void spl_board_prepare_for_linux(void);
+void spl_board_prepare_for_boot(void);
 void __noreturn jump_to_image_linux(void *arg);
 int spl_start_uboot(void);
 void spl_display_print(void);