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Commit d0788ce4 authored by Stefan Roese's avatar Stefan Roese Committed by David Woodhouse
Browse files

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: default avatarStefan Roese <sr@denx.de>
Signed-off-by: default avatarArtem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: default avatarDavid Woodhouse <David.Woodhouse@intel.com>
parent e1ed147f

Documentation/devicetree/bindings/mtd/mtd-physmap.txt

+7 −0
Original line number Diff line number Diff line
@@ -16,6 +16,13 @@ file systems on embedded devices. 
 - #address-cells, #size-cells : Must be present if the device has

   sub-nodes representing partitions (see below).  In this case

   both #address-cells and #size-cells must be equal to 1.

 - no-unaligned-direct-access: boolean to disable the default direct

   mapping of the flash.

   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.



For JEDEC compatible devices, the following additional properties

are defined:

drivers/mtd/maps/physmap_of.c

+14 −0
Original line number Diff line number Diff line
@@ -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);