mips: add a option to support not reserving malloc space on initial stack

The initial stack on some platforms is too small to hold a large malloc
space. This patch adds a option to allow these platforms not reserving the
malloc space on initial stack. These platforms should set the malloc base
after DRAM is usable.

Reviewed-by: Stefan Roese <sr@denx.de>
Signed-off-by: Weijie Gao <weijie.gao@mediatek.com>

arch/mips/Kconfig

@@ -317,6 +317,24 @@ config NEW_EXCEPTION_VECTOR_BASE
 	help
 	  The exception vector base to be restored before booting linux kernel
 
+config INIT_STACK_WITHOUT_MALLOC_F
+	bool "Do not reserve malloc space on initial stack"
+	default n
+	help
+	  Enable this option if you don't want to reserve malloc space on
+	  initial stack. This is useful if the initial stack can't hold large
+	  malloc space. Platform should set the malloc_base later when DRAM is
+	  ready to use.
+
+config SPL_INIT_STACK_WITHOUT_MALLOC_F
+	bool "Do not reserve malloc space on initial stack in SPL"
+	default n
+	help
+	  Enable this option if you don't want to reserve malloc space on
+	  initial stack. This is useful if the initial stack can't hold large
+	  malloc space. Platform should set the malloc_base later when DRAM is
+	  ready to use.
+
 config SPL_LOADER_SUPPORT
 	bool
 	default n

arch/mips/cpu/start.S

@@ -59,7 +59,8 @@
 		sp, sp, GD_SIZE		# reserve space for gd
 	and	sp, sp, t0		# force 16 byte alignment
 	move	k0, sp			# save gd pointer
-#if CONFIG_VAL(SYS_MALLOC_F_LEN)
+#if CONFIG_VAL(SYS_MALLOC_F_LEN) && \
+    !CONFIG_IS_ENABLED(INIT_STACK_WITHOUT_MALLOC_F)
 	li	t2, CONFIG_VAL(SYS_MALLOC_F_LEN)
 	PTR_SUBU \
 		sp, sp, t2		# reserve space for early malloc
@@ -75,7 +76,8 @@
 	blt	t0, t1, 1b
 	 nop
 
-#if CONFIG_VAL(SYS_MALLOC_F_LEN)
+#if CONFIG_VAL(SYS_MALLOC_F_LEN) && \
+    !CONFIG_IS_ENABLED(INIT_STACK_WITHOUT_MALLOC_F)
 	PTR_S	sp, GD_MALLOC_BASE(k0)	# gd->malloc_base offset
 #endif
 	.endm