[PATCH v2] mtd: physmap_of: Add "no-unaligned-direct-access" DT property
From: sr@denx.de (Stefan Roese)
Date: 2012-08-17 13:22:32
Also in:
linux-devicetree
Subsystem:
memory technology devices (mtd), open firmware and flattened device tree bindings, the rest · Maintainers:
Miquel Raynal, Richard Weinberger, Vignesh Raghavendra, Rob Herring, Krzysztof Kozlowski, Conor Dooley, Linus Torvalds
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> Cc: Stephan Gatzka <redacted> Cc: Anatolij Gustschin <agust@denx.de> Cc: Albrecht Dress <redacted> Cc: Artem Bityutskiy <dedekind1@gmail.com> Cc: David Woodhouse <dwmw2@infradead.org> --- v2: - Changed "map-indirect" to "no-unaligned-direct-access" because of David's comments. Documentation/devicetree/bindings/mtd/mtd-physmap.txt | 7 +++++++ drivers/mtd/maps/physmap_of.c | 14 ++++++++++++++ 2 files changed, 21 insertions(+)
diff --git a/Documentation/devicetree/bindings/mtd/mtd-physmap.txt b/Documentation/devicetree/bindings/mtd/mtd-physmap.txt
index a63c2bd7..94de19b 100644
--- a/Documentation/devicetree/bindings/mtd/mtd-physmap.txt
+++ b/Documentation/devicetree/bindings/mtd/mtd-physmap.txt@@ -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:
diff --git a/drivers/mtd/maps/physmap_of.c b/drivers/mtd/maps/physmap_of.c
index 2e6fb68..6f19aca 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);
--
1.7.11.2