spl: Add spl_early_init()

At present malloc_base/_limit/_ptr are not initialised in spl_init() when
we call spl_init() in board_init_f(). This is due to a recent change aimed
at avoiding overwriting the malloc area set up on some boards by
spl_relocate_stack_gd().

However if CONFIG_SPL_STACK_R_MALLOC_SIMPLE_LEN is not defined, we now
skip setting up the memory area in spl_init() which is obviously wrong.

To fix this, add a new function spl_early_init() which can be called in
board_init_f().

Fixes: b3d2861e (spl: Remove overwrite of relocated malloc limit)
Signed-off-by: Eddie Cai <eddie.cai.linux@gmail.com>
Rewrote spl_{,early_}init() to avoid duplicate code:
Rewrite/expand commit message:
Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Eddie Cai <eddie.cai.linux@gmail.com>
diff --git a/include/asm-generic/global_data.h b/include/asm-generic/global_data.h
index e02863d..5b356dd 100644
--- a/include/asm-generic/global_data.h
+++ b/include/asm-generic/global_data.h
@@ -127,5 +127,6 @@
 #define GD_FLG_SKIP_RELOC	0x00800	/* Don't relocate		   */
 #define GD_FLG_RECORD		0x01000	/* Record console		   */
 #define GD_FLG_ENV_DEFAULT	0x02000 /* Default variable flag	   */
+#define GD_FLG_SPL_EARLY_INIT	0x04000 /* Early SPL init is done	   */
 
 #endif /* __ASM_GENERIC_GBL_DATA_H */
diff --git a/include/spl.h b/include/spl.h
index bde4437..cdd196d 100644
--- a/include/spl.h
+++ b/include/spl.h
@@ -213,11 +213,29 @@
 			  struct blk_desc *block_dev, int partition);
 
 /**
- * spl_init() - Set up device tree and driver model in SPL if enabled
+ * spl_early_init() - Set up device tree and driver model in SPL if enabled
  *
  * Call this function in board_init_f() if you want to use device tree and
- * driver model early, before board_init_r() is called. This function will
- * be called from board_init_r() if not called earlier.
+ * driver model early, before board_init_r() is called.
+ *
+ * If this is not called, then driver model will be inactive in SPL's
+ * board_init_f(), and no device tree will be available.
+ */
+int spl_early_init(void);
+
+/**
+ * spl_init() - Set up device tree and driver model in SPL if enabled
+ *
+ * You can optionally call spl_early_init(), then optionally call spl_init().
+ * This function will be called from board_init_r() if not called earlier.
+ *
+ * Both spl_early_init() and spl_init() perform a similar function except that
+ * the latter will not set up the malloc() area if
+ * CONFIG_SPL_STACK_R_MALLOC_SIMPLE_LEN is enabled, since it is assumed to
+ * already be done by a calll to spl_relocate_stack_gd() before board_init_r()
+ * is reached.
+ *
+ * This function will be called from board_init_r() if not called earlier.
  *
  * If this is not called, then driver model will be inactive in SPL's
  * board_init_f(), and no device tree will be available.