[PATCH] memsize: Make get_ram_size() work with arbitary RAM size

[Bin Meng]

From: Bin Meng <bin.meng at windriver.com>

Currently get_ram_size() only works with certain RAM size like 1GiB,
2GiB, 4GiB, 8GiB, etc. Chanage the codes to work with any RAM size.

Signed-off-by: Bin Meng <bin.meng at windriver.com>
---

 common/memsize.c | 28 +++++++++++++++++-----------
 1 file changed, 17 insertions(+), 11 deletions(-)

diff --git a/common/memsize.c b/common/memsize.c
index e95c682..776737a 100644
--- a/common/memsize.c
+++ b/common/memsize.c
@@ -6,6 +6,7 @@
 
 #include <common.h>
 #include <init.h>
+#include <linux/bitops.h>
 
 DECLARE_GLOBAL_DATA_PTR;
 
@@ -27,14 +28,18 @@ DECLARE_GLOBAL_DATA_PTR;
 long get_ram_size(long *base, long maxsize)
 {
 	volatile long *addr;
-	long           save[BITS_PER_LONG - 1];
-	long           save_base;
-	long           cnt;
-	long           val;
-	long           size;
-	int            i = 0;
+	long save[BITS_PER_LONG - 1];
+	long save_base;
+	long cnt;
+	long val;
+	long size;
+	int i = 0;
+	long n = maxsize / sizeof(long);
 
-	for (cnt = (maxsize / sizeof(long)) >> 1; cnt > 0; cnt >>= 1) {
+	n = __ffs(n);
+	n = BIT(n);
+
+	for (cnt = n >> 1; cnt > 0; cnt >>= 1) {
 		addr = base + cnt;	/* pointer arith! */
 		sync();
 		save[i++] = *addr;
@@ -53,7 +58,7 @@ long get_ram_size(long *base, long maxsize)
 		/* Restore the original data before leaving the function. */
 		sync();
 		*base = save_base;
-		for (cnt = 1; cnt < maxsize / sizeof(long); cnt <<= 1) {
+		for (cnt = 1; cnt < n; cnt <<= 1) {
 			addr  = base + cnt;
 			sync();
 			*addr = save[--i];
@@ -61,7 +66,7 @@ long get_ram_size(long *base, long maxsize)
 		return (0);
 	}
 
-	for (cnt = 1; cnt < maxsize / sizeof(long); cnt <<= 1) {
+	for (cnt = 1; cnt < n; cnt <<= 1) {
 		addr = base + cnt;	/* pointer arith! */
 		val = *addr;
 		*addr = save[--i];
@@ -72,12 +77,13 @@ long get_ram_size(long *base, long maxsize)
 			 * before leaving the function.
 			 */
 			for (cnt <<= 1;
-			     cnt < maxsize / sizeof(long);
+			     cnt < n;
 			     cnt <<= 1) {
 				addr  = base + cnt;
 				*addr = save[--i];
 			}
-			/* warning: don't restore save_base in this case,
+			/*
+			 * warning: don't restore save_base in this case,
 			 * it is already done in the loop because
 			 * base and base+size share the same physical memory
 			 * and *base is saved after *(base+size) modification
-- 
2.7.4