malloc_simple: Add support for switching to DRAM heap

malloc_simple uses a part of the stack as heap, initially it uses
SYS_MALLOC_F_LEN bytes which typically is quite small as the initial
stacks sits in SRAM and we do not have that much SRAM to work with.

When DRAM becomes available we may switch the stack from SRAM to DRAM
to give use more room. This commit adds support for also switching to
a new bigger malloc_simple heap located in the new stack.

Note that this requires spl_init to be called before spl_relocate_stack_gd
which in practice means that spl_init must be called from board_init_f.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Acked-by: Simon Glass <sjg@chromium.org>

Kconfig

@@ -142,6 +142,16 @@ config SPL_STACK_R_ADDR
 	  Specify the address in SDRAM for the SPL stack. This will be set up
 	  before board_init_r() is called.
 
+config SPL_STACK_R_MALLOC_SIMPLE_LEN
+	depends on SPL_STACK_R && SPL_SYS_MALLOC_SIMPLE
+	hex "Size of malloc_simple heap after switching to DRAM SPL stack"
+	default 0x100000
+	help
+	  Specify the amount of the stack to use as memory pool for
+	  malloc_simple after switching the stack to DRAM. This may be set
+	  to give board_init_r() a larger heap then the initial heap in
+	  SRAM which is limited to SYS_MALLOC_F_LEN bytes.
+
 config TPL
 	bool
 	depends on SPL && SUPPORT_TPL

common/spl/spl.c

@@ -347,6 +347,18 @@ ulong spl_relocate_stack_gd(void)
 	memcpy(new_gd, (void *)gd, sizeof(gd_t));
 	gd = new_gd;
 
+#ifdef CONFIG_SPL_SYS_MALLOC_SIMPLE
+	if (CONFIG_SPL_STACK_R_MALLOC_SIMPLE_LEN) {
+		if (!(gd->flags & GD_FLG_SPL_INIT))
+			panic("spl_init must be called before heap reloc");
+
+		ptr -= CONFIG_SPL_STACK_R_MALLOC_SIMPLE_LEN;
+		gd->malloc_base = ptr;
+		gd->malloc_limit = CONFIG_SPL_STACK_R_MALLOC_SIMPLE_LEN;
+		gd->malloc_ptr = 0;
+	}
+#endif
+
 	return ptr;
 #else
 	return 0;