[U-Boot] [PATCH 5/7] FAT: get_cluster: Add buffer bouncing

[Benoît Thébaudeau]

Add a buffer bouncing mechanism to get_cluster. This can be useful for
misaligned applicative buffers passed through get_contents. This is required for
the following patches in the case of data aligned differently relatively to
buffers and clusters.

Signed-off-by: Benoît Thébaudeau <benoit.thebaudeau at advansee.com>
Cc: Wolfgang Denk <wd at denx.de>
---
 .../fs/fat/fat.c                                   |   42 ++++++++++++++------
 1 file changed, 30 insertions(+), 12 deletions(-)

diff --git u-boot-66714b1.orig/fs/fat/fat.c u-boot-66714b1/fs/fat/fat.c
index 943cdb6..4c80820 100644
--- u-boot-66714b1.orig/fs/fat/fat.c
+++ u-boot-66714b1/fs/fat/fat.c
@@ -274,7 +274,6 @@ get_cluster (fsdata *mydata, __u32 clustnum, __u8 *buffer,
 {
 	__u32 idx = 0;
 	__u32 startsect;
-	__u32 nr_sect;
 	int ret;
 
 	if (clustnum > 0) {
@@ -286,25 +285,44 @@ get_cluster (fsdata *mydata, __u32 clustnum, __u8 *buffer,
 
 	debug("gc - clustnum: %d, startsect: %d\n", clustnum, startsect);
 
-	nr_sect = size / mydata->sect_size;
-	ret = disk_read(startsect, nr_sect, buffer);
-	if (ret != nr_sect) {
-		debug("Error reading data (got %d)\n", ret);
-		return -1;
-	}
-	if (size % mydata->sect_size) {
+	if ((unsigned long)buffer & (ARCH_DMA_MINALIGN - 1)) {
 		ALLOC_CACHE_ALIGN_BUFFER(__u8, tmpbuf, mydata->sect_size);
 
+		debug("FAT: Misaligned buffer address (%p)\n", buffer);
+
+		while (size >= mydata->sect_size) {
+			ret = disk_read(startsect++, 1, tmpbuf);
+			if (ret != 1) {
+				debug("Error reading data (got %d)\n", ret);
+				return -1;
+			}
+
+			memcpy(buffer, tmpbuf, mydata->sect_size);
+			buffer += mydata->sect_size;
+			size -= mydata->sect_size;
+		}
+	} else {
 		idx = size / mydata->sect_size;
-		ret = disk_read(startsect + idx, 1, tmpbuf);
+		ret = disk_read(startsect, idx, buffer);
+		if (ret != idx) {
+			debug("Error reading data (got %d)\n", ret);
+			return -1;
+		}
+		startsect += idx;
+		idx *= mydata->sect_size;
+		buffer += idx;
+		size -= idx;
+	}
+	if (size) {
+		ALLOC_CACHE_ALIGN_BUFFER(__u8, tmpbuf, mydata->sect_size);
+
+		ret = disk_read(startsect, 1, tmpbuf);
 		if (ret != 1) {
 			debug("Error reading data (got %d)\n", ret);
 			return -1;
 		}
-		buffer += idx * mydata->sect_size;
 
-		memcpy(buffer, tmpbuf, size % mydata->sect_size);
-		return 0;
+		memcpy(buffer, tmpbuf, size);
 	}
 
 	return 0;