Add a simple malloc() implementation for pre-relocation

If we are to have driver model before relocation we need to support some
way of calling memory allocation routines.

The standard malloc() is pretty complicated:

1. It uses some BSS memory for its state, and BSS is not available before
relocation

2. It supports algorithms for reducing memory fragmentation and improving
performace of free(). Before relocation we could happily just not support
free().

3. It includes about 4KB of code (Thumb 2) and 1KB of data. However since
this has been loaded anyway this is not really a problem.

The simplest way to support pre-relocation malloc() is to reserve an area
of memory and allocate it in increasing blocks as needed. This
implementation does this.

To enable it, you need to define the size of the malloc() pool as described
in the README. It will be located above the pre-relocation stack on
supported architectures.

Note that this implementation is only useful on machines which have some
memory available before dram_init() is called - this includes those that
do no DRAM init (like tegra) and those that do it in SPL (quite a few
boards). Enabling driver model preior to relocation for the rest of the
boards is left for a later exercise.

Signed-off-by: Simon Glass <sjg@chromium.org>

3 files changed, 51 insertions, 0 deletions

diff --git a/common/board_f.c b/common/board_f.c
index bdab38e89d..6b2e277bd7 100644
--- a/common/board_f.c
+++ b/common/board_f.c
@@ -767,6 +767,17 @@ static int mark_bootstage(void)
 	return 0;
 }
 
+static int initf_malloc(void)
+{
+#ifdef CONFIG_SYS_MALLOC_F_LEN
+	assert(gd->malloc_base);	/* Set up by crt0.S */
+	gd->malloc_limit = gd->malloc_base + CONFIG_SYS_MALLOC_F_LEN;
+	gd->malloc_ptr = 0;
+#endif
+
+	return 0;
+}
+
 static init_fnc_t init_sequence_f[] = {
 #ifdef CONFIG_SANDBOX
 	setup_ram_buf,
@@ -824,6 +835,7 @@ static init_fnc_t init_sequence_f[] = {
 	sdram_adjust_866,
 	init_timebase,
 #endif
+	initf_malloc,
 	init_baud_rate,		/* initialze baudrate settings */
 	serial_init,		/* serial communications setup */
 	console_init_f,		/* stage 1 init of console */
diff --git a/common/board_r.c b/common/board_r.c
index 4479acbb72..2298ba5761 100644
--- a/common/board_r.c
+++ b/common/board_r.c
@@ -259,6 +259,10 @@ static int initr_malloc(void)
 {
 	ulong malloc_start;
 
+#ifdef CONFIG_SYS_MALLOC_F_LEN
+	debug("Pre-reloc malloc() used %#lx bytes (%ld KB)\n", gd->malloc_ptr,
+	      gd->malloc_ptr / 1024);
+#endif
 	/* The malloc area is immediately below the monitor copy in DRAM */
 	malloc_start = gd->relocaddr - TOTAL_MALLOC_LEN;
 	mem_malloc_init((ulong)map_sysmem(malloc_start, TOTAL_MALLOC_LEN),
diff --git a/common/dlmalloc.c b/common/dlmalloc.c
index d1cd561cb8..26ba8fd622 100644
--- a/common/dlmalloc.c
+++ b/common/dlmalloc.c
@@ -930,6 +930,8 @@ struct mallinfo mALLINFo();
 #endif	/* 0 */			/* Moved to malloc.h */
 
 #include <malloc.h>
+#include <asm/io.h>
+
 #ifdef DEBUG
 #if __STD_C
 static void malloc_update_mallinfo (void);
@@ -2174,6 +2176,20 @@ Void_t* mALLOc(bytes) size_t bytes;
 
   INTERNAL_SIZE_T nb;
 
+#ifdef CONFIG_SYS_MALLOC_F_LEN
+	if (!(gd->flags & GD_FLG_RELOC)) {
+		ulong new_ptr;
+		void *ptr;
+
+		new_ptr = gd->malloc_ptr + bytes;
+		if (new_ptr > gd->malloc_limit)
+			panic("Out of pre-reloc memory");
+		ptr = map_sysmem(gd->malloc_base + gd->malloc_ptr, bytes);
+		gd->malloc_ptr = ALIGN(new_ptr, sizeof(new_ptr));
+		return ptr;
+	}
+#endif
+
   /* check if mem_malloc_init() was run */
   if ((mem_malloc_start == 0) && (mem_malloc_end == 0)) {
     /* not initialized yet */
@@ -2437,6 +2453,12 @@ void fREe(mem) Void_t* mem;
   mchunkptr fwd;       /* misc temp for linking */
   int       islr;      /* track whether merging with last_remainder */
 
+#ifdef CONFIG_SYS_MALLOC_F_LEN
+	/* free() is a no-op - all the memory will be freed on relocation */
+	if (!(gd->flags & GD_FLG_RELOC))
+		return;
+#endif
+
   if (mem == NULL)                              /* free(0) has no effect */
     return;
 
@@ -2588,6 +2610,13 @@ Void_t* rEALLOc(oldmem, bytes) Void_t* oldmem; size_t bytes;
   /* realloc of null is supposed to be same as malloc */
   if (oldmem == NULL) return mALLOc(bytes);
 
+#ifdef CONFIG_SYS_MALLOC_F_LEN
+	if (!(gd->flags & GD_FLG_RELOC)) {
+		/* This is harder to support and should not be needed */
+		panic("pre-reloc realloc() is not supported");
+	}
+#endif
+
   newp    = oldp    = mem2chunk(oldmem);
   newsize = oldsize = chunksize(oldp);
 
@@ -2933,6 +2962,12 @@ Void_t* cALLOc(n, elem_size) size_t n; size_t elem_size;
     return NULL;
   else
   {
+#ifdef CONFIG_SYS_MALLOC_F_LEN
+	if (!(gd->flags & GD_FLG_RELOC)) {
+		MALLOC_ZERO(mem, sz);
+		return mem;
+	}
+#endif
     p = mem2chunk(mem);
 
     /* Two optional cases in which clearing not necessary */