spl: Make image loader infrastructure more universal

The current U-Boot SPL image loader infrastructure is very powerful,
able to initialize and load from a variety of boot media however it
is strongly geared towards loading specific types of images in a very
specific way. To address the need being able to use this infrastructure
to load arbitrary image files go ahead and refactor it as follows:

- Refactor existing spl_mmc_load_image function into superset function,
  accepting additional arguments such as filenames and media load offset
  (same concept can also be applied toother spl_XXX_load_image functions)
- Extend the loader function to "remember" their peripheral initialization
  status so that the init is only done once during the boot process,
- Extend the FIT image loading function to allow skipping the parsing/
  processing of the FIT contents (so that this can be done separately
  in a more customized fashion)
- Populate the SPL_LOAD_IMAGE_METHOD() list with a trampoline function,
  invoking the newly refactored superset functions in a way to maintain
  compatibility with the existing behavior

This refactoring initially covers MMC/SD card loading (RAW and FS-based).

Signed-off-by: Andreas Dannenberg <dannenberg@ti.com>
Reviewed-by: Tom Rini <trini@konsulko.com>

1 files changed, 14 insertions, 0 deletions

diff --git a/common/spl/spl_fit.c b/common/spl/spl_fit.c
index 87ecf0bb9e..969f7775c1 100644
--- a/common/spl/spl_fit.c
+++ b/common/spl/spl_fit.c
@@ -340,6 +340,16 @@ static int spl_fit_image_get_os(const void *fit, int noffset, uint8_t *os)
 #endif
 }
 
+/*
+ * Weak default function to allow customizing SPL fit loading for load-only
+ * use cases by allowing to skip the parsing/processing of the FIT contents
+ * (so that this can be done separately in a more customized fashion)
+ */
+__weak bool spl_load_simple_fit_skip_processing(void)
+{
+	return false;
+}
+
 int spl_load_simple_fit(struct spl_image_info *spl_image,
 			struct spl_load_info *info, ulong sector, void *fit)
 {
@@ -389,6 +399,10 @@ int spl_load_simple_fit(struct spl_image_info *spl_image,
 	if (count == 0)
 		return -EIO;
 
+	/* skip further processing if requested to enable load-only use cases */
+	if (spl_load_simple_fit_skip_processing())
+		return 0;
+
 	/* find the node holding the images information */
 	images = fdt_path_offset(fit, FIT_IMAGES_PATH);
 	if (images < 0) {