[U-Boot] [PATCH v1 16/19] lib: fdtdec: Add function re-setup the fdt more effeciently

[Jean-Jacques Hiblot]

In some cases it may be useful to be able to change the fdt we have been
using and use another one instead. For example, the TI platforms uses an
EEPROM to store board information and, based on the type of board,
different dtbs are used by the SPL. When DM_I2C is used, a first dtb must
be used before the I2C is initialized and only then the final dtb can be
selected.
To speed up the process and reduce memory usage, introduce a new function
fdtdec_setup_best_match() that re-use the DTBs loaded in memory by
fdtdec_setup() to select the best match.

Signed-off-by: Jean-Jacques Hiblot <jjhiblot at ti.com>
---

 include/asm-generic/global_data.h |  4 ++++
 include/fdtdec.h                  | 17 +++++++++++++++++
 lib/fdtdec.c                      | 38 +++++++++++++++++++++++++++++++++++++-
 3 files changed, 58 insertions(+), 1 deletion(-)

diff --git a/include/asm-generic/global_data.h b/include/asm-generic/global_data.h
index c83fc01..49287fa 100644
--- a/include/asm-generic/global_data.h
+++ b/include/asm-generic/global_data.h
@@ -77,6 +77,10 @@ typedef struct global_data {
 #ifdef CONFIG_OF_LIVE
 	struct device_node *of_root;
 #endif
+
+#if CONFIG_IS_ENABLED(MULTI_DTB_FIT)
+	const void *multi_dtb_fit;
+#endif
 	struct jt_funcs *jt;		/* jump table */
 	char env_buf[32];		/* buffer for env_get() before reloc. */
 #ifdef CONFIG_TRACE
diff --git a/include/fdtdec.h b/include/fdtdec.h
index 83be064..2cb3da2 100644
--- a/include/fdtdec.h
+++ b/include/fdtdec.h
@@ -996,6 +996,23 @@ int fdtdec_setup_memory_banksize(void);
  */
 int fdtdec_setup(void);
 
+#if CONFIG_IS_ENABLED(MULTI_DTB_FIT)
+/**
+ * fdtdec_resetup()  - Set up the device tree ready for use again.
+ *
+ * The main difference with fdtdec_setup() is that it returns if the fdt has
+ * changed because a better match has been found.
+ * This is typically used for boards that rely on a DM driver to detect the
+ * board type.
+ *
+ * @param rescan Return a flag indicating that fdt has changed and rescaning the
+ *               fdt is required.
+ *
+ * @return 0 if OK, -ve on error
+ */
+int fdtdec_resetup(int *rescan);
+#endif
+
 /**
  * Board-specific FDT initialization. Returns the address to a device tree blob.
  * Called when CONFIG_OF_BOARD is defined, or if CONFIG_OF_SEPARATE is defined
diff --git a/lib/fdtdec.c b/lib/fdtdec.c
index 74196ce..3b80bd4 100644
--- a/lib/fdtdec.c
+++ b/lib/fdtdec.c
@@ -1353,14 +1353,50 @@ int fdtdec_setup(void)
 	 * If so, pick the most relevant
 	 */
 	fdt_blob = locate_dtb_in_fit(gd->fdt_blob);
-	if (fdt_blob)
+	if (fdt_blob) {
+		gd->multi_dtb_fit = gd->fdt_blob;
 		gd->fdt_blob = fdt_blob;
+	}
+
 # endif
 #endif
 
 	return fdtdec_prepare_fdt();
 }
 
+#if CONFIG_IS_ENABLED(MULTI_DTB_FIT)
+int fdtdec_resetup(int *rescan)
+{
+	void *fdt_blob;
+
+	/*
+	 * If the current DTB is part of a compressed FIT image,
+	 * try to locate the best match from the uncompressed
+	 * FIT image stillpresent there. Save the time and space
+	 * required to uncompress it again.
+	 */
+	if (gd->multi_dtb_fit) {
+		fdt_blob = locate_dtb_in_fit(gd->multi_dtb_fit);
+
+		if (fdt_blob == gd->fdt_blob) {
+			/*
+			 * The best match did not change. no need to tear down
+			 * the DM and rescan the fdt.
+			 */
+			*rescan = 0;
+			return 0;
+		}
+
+		*rescan = 1;
+		gd->fdt_blob = fdt_blob;
+		return fdtdec_prepare_fdt();
+	}
+
+	*rescan = 1;
+	return fdtdec_setup();
+}
+#endif
+
 #ifdef CONFIG_NR_DRAM_BANKS
 int fdtdec_decode_ram_size(const void *blob, const char *area, int board_id,
 			   phys_addr_t *basep, phys_size_t *sizep, bd_t *bd)
-- 
2.7.4