[U-Boot] [PATCH] malloc_simple: Add simple malloc free function

[Chin Liang See]

Enable a simple malloc implementation which will minimize
memory usage prior relocation. This is essential as memory
available prior location is internal memory and limited in
size.

This implementation will stored last 2 usage of malloc. When
free is invoked and the free address matched, we shall revert
to previous value of gd->malloc_ptr that we stored.

Signed-off-by: Chin Liang See <clsee at altera.com>
Cc: Marek Vasut <marex at denx.de>
Cc: Simon Glass <sjg at chromium.org>
Cc: Tom Rini <trini at konsulko.com>
Cc: Dinh Nguyen <dinguyen at opensource.altera.com>
Cc: Tien Fong Chee <tfchee at altera.com>
---
 common/dlmalloc.c                 |  6 ++++--
 common/malloc_simple.c            | 34 ++++++++++++++++++++++++++++++++++
 include/asm-generic/global_data.h |  2 ++
 include/malloc.h                  |  3 ++-
 4 files changed, 42 insertions(+), 3 deletions(-)

diff --git a/common/dlmalloc.c b/common/dlmalloc.c
index adc680e..ba42d0d 100644
--- a/common/dlmalloc.c
+++ b/common/dlmalloc.c
@@ -1523,9 +1523,11 @@ void fREe(mem) Void_t* mem;
   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_FULL_MALLOC_INIT))
+	/* Invoke free_simple. All the memory will be freed on relocation */
+	if (!(gd->flags & GD_FLG_FULL_MALLOC_INIT)) {
+		free_simple(mem);
 		return;
+	}
 #endif
 
   if (mem == NULL)                              /* free(0) has no effect */
diff --git a/common/malloc_simple.c b/common/malloc_simple.c
index 0f6bcbc..383a546 100644
--- a/common/malloc_simple.c
+++ b/common/malloc_simple.c
@@ -26,6 +26,18 @@ void *malloc_simple(size_t bytes)
 		return NULL;
 	}
 	ptr = map_sysmem(gd->malloc_base + gd->malloc_ptr, bytes);
+
+	/* implement a simple free mechanism which stored last 2 usage */
+	if (gd->malloc_free_addr[0] != 0) {
+		/* shifting as we are storing depth of 2 */
+		gd->malloc_free_addr[1] = gd->malloc_free_addr[0];
+		gd->malloc_free_ptr[1] = gd->malloc_free_ptr[0];
+	}
+	/* saving last malloc address for malloc free */
+	gd->malloc_free_addr[0] = ptr;
+	/* saving last malloc_ptr prior allocation for malloc free */
+	gd->malloc_free_ptr[0] = gd->malloc_ptr;
+
 	gd->malloc_ptr = ALIGN(new_ptr, sizeof(new_ptr));
 	debug("%lx\n", (ulong)ptr);
 
@@ -42,6 +54,18 @@ void *memalign_simple(size_t align, size_t bytes)
 	if (new_ptr > gd->malloc_limit)
 		return NULL;
 	ptr = map_sysmem(addr, bytes);
+
+	/* implement a simple free mechanism which stored last 2 usage */
+	if (gd->malloc_free_addr[0] != 0) {
+		/* shifting as we are storing depth of 2 */
+		gd->malloc_free_addr[1] = gd->malloc_free_addr[0];
+		gd->malloc_free_ptr[1] = gd->malloc_free_ptr[0];
+	}
+	/* saving last malloc address for malloc free */
+	gd->malloc_free_addr[0] = ptr;
+	/* saving last malloc_ptr prior allocation for malloc free */
+	gd->malloc_free_ptr[0] = gd->malloc_ptr;
+
 	gd->malloc_ptr = ALIGN(new_ptr, sizeof(new_ptr));
 
 	return ptr;
@@ -59,3 +83,13 @@ void *calloc(size_t nmemb, size_t elem_size)
 	return ptr;
 }
 #endif
+
+void free_simple(Void_t* mem)
+{
+	if (mem == gd->malloc_free_addr[0]) {
+		gd->malloc_ptr = gd->malloc_free_ptr[0];
+		/* shifting as we are storing depth of 2 */
+		gd->malloc_free_addr[0] = gd->malloc_free_addr[1];
+		gd->malloc_free_ptr[0] = gd->malloc_free_ptr[1];
+	}
+}
diff --git a/include/asm-generic/global_data.h b/include/asm-generic/global_data.h
index a6d1d2a..9380772 100644
--- a/include/asm-generic/global_data.h
+++ b/include/asm-generic/global_data.h
@@ -90,6 +90,8 @@ typedef struct global_data {
 	unsigned long malloc_base;	/* base address of early malloc() */
 	unsigned long malloc_limit;	/* limit address */
 	unsigned long malloc_ptr;	/* current address */
+	void *malloc_free_addr[2];	/* Last malloc pointer address*/
+	unsigned long malloc_free_ptr[2];	/* Last malloc_ptr */
 #endif
 #ifdef CONFIG_PCI
 	struct pci_controller *hose;	/* PCI hose for early use */
diff --git a/include/malloc.h b/include/malloc.h
index 8175c75..02651aa 100644
--- a/include/malloc.h
+++ b/include/malloc.h
@@ -876,7 +876,7 @@ extern Void_t*     sbrk();
 #define malloc malloc_simple
 #define realloc realloc_simple
 #define memalign memalign_simple
-static inline void free(void *ptr) {}
+#define free free_simple
 void *calloc(size_t nmemb, size_t size);
 void *memalign_simple(size_t alignment, size_t bytes);
 void *realloc_simple(void *ptr, size_t size);
@@ -913,6 +913,7 @@ int initf_malloc(void);
 
 /* Simple versions which can be used when space is tight */
 void *malloc_simple(size_t size);
+void free_simple(Void_t* mem);
 
 #pragma GCC visibility push(hidden)
 # if __STD_C
-- 
2.2.2