mtd: physmap_of: Add "no-unaligned-direct-access" DT property

On some platforms (e.g. MPC5200) a direct 1:1 mapping may cause
problems with JFFS2 usage, as the local bus (LPB) doesn't support
unaligned accesses as implemented in the JFFS2 code via memcpy().
By defining "no-unaligned-direct-access", the flash will not be
exposed directly to the MTD users (e.g. JFFS2) any more.

Signed-off-by: Stefan Roese <sr@denx.de>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

1 files changed, 14 insertions, 0 deletions

diff --git a/drivers/mtd/maps/physmap_of.c b/drivers/mtd/maps/physmap_of.c
index 2e6fb6831d55..6f19acadb06c 100644
--- a/drivers/mtd/maps/physmap_of.c
+++ b/drivers/mtd/maps/physmap_of.c
@@ -169,6 +169,7 @@ static int __devinit of_flash_probe(struct platform_device *dev)
         struct mtd_info **mtd_list = NULL;
         resource_size_t res_size;
         struct mtd_part_parser_data ppdata;
+        bool map_indirect;
 
         match = of_match_device(of_flash_match, &dev->dev);
         if (!match)
@@ -192,6 +193,8 @@ static int __devinit of_flash_probe(struct platform_device *dev)
         }
         count /= reg_tuple_size;
 
+        map_indirect = of_property_read_bool(dp, "no-unaligned-direct-access");
+
         err = -ENOMEM;
         info = kzalloc(sizeof(struct of_flash) +
                        sizeof(struct of_flash_list) * count, GFP_KERNEL);
@@ -247,6 +250,17 @@ static int __devinit of_flash_probe(struct platform_device *dev)
 
                 simple_map_init(&info->list[i].map);
 
+                /*
+                 * On some platforms (e.g. MPC5200) a direct 1:1 mapping
+                 * may cause problems with JFFS2 usage, as the local bus (LPB)
+                 * doesn't support unaligned accesses as implemented in the
+                 * JFFS2 code via memcpy(). By setting NO_XIP, the
+                 * flash will not be exposed directly to the MTD users
+                 * (e.g. JFFS2) any more.
+                 */
+                if (map_indirect)
+                        info->list[i].map.phys = NO_XIP;
+
                 if (probe_type) {
                         info->list[i].mtd = do_map_probe(probe_type,
                                                          &info->list[i].map);