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authorWolfram Sang <w.sang@pengutronix.de>2009-07-17 12:39:23 (GMT)
committerDavid Woodhouse <David.Woodhouse@intel.com>2009-09-19 20:15:26 (GMT)
commitfc28c39f0ef59bfb649ddfd633275be8e45c0f9c (patch)
tree7a1e8d0b1bc015b5cc9584db3ac7805269036479 /Documentation/powerpc
parent223cf6c3b517cf6ef040cafe45af89f3b8adba74 (diff)
mtd: maps: add mtd-ram support to physmap_of
Use physmap_of to access RAMs as mtd and add documenation for it. This approach is a lot less intrusive as adding an of-wrapper around plat-ram.c. As most extensions of plat-ram.c (e.g. custom map-functions) can't be mapped to the device tree anyhow, extending physmap_of seems to be the cleanest approach. Tested with a phyCORE-MPC5121e. Signed-off-by: Wolfram Sang <w.sang@pengutronix.de> Cc: Vitaly Wool <vwool@ru.mvista.com> Cc: Artem Bityutskiy <dedekind@infradead.org> Cc: Ken MacLeod <ken@bitsko.slc.ut.us> Cc: Albrecht DreƟ <albrecht.dress@arcor.de> Acked-by: Grant Likely <grant.likely@secretlab.ca> Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Diffstat (limited to 'Documentation/powerpc')
-rw-r--r--Documentation/powerpc/dts-bindings/mtd-physmap.txt42
1 files changed, 26 insertions, 16 deletions
diff --git a/Documentation/powerpc/dts-bindings/mtd-physmap.txt b/Documentation/powerpc/dts-bindings/mtd-physmap.txt
index 667c9bd..80152cb 100644
--- a/Documentation/powerpc/dts-bindings/mtd-physmap.txt
+++ b/Documentation/powerpc/dts-bindings/mtd-physmap.txt
@@ -1,18 +1,19 @@
-CFI or JEDEC memory-mapped NOR flash
+CFI or JEDEC memory-mapped NOR flash, MTD-RAM (NVRAM...)
Flash chips (Memory Technology Devices) are often used for solid state
file systems on embedded devices.
- - compatible : should contain the specific model of flash chip(s)
- used, if known, followed by either "cfi-flash" or "jedec-flash"
- - reg : Address range(s) of the flash chip(s)
+ - compatible : should contain the specific model of mtd chip(s)
+ used, if known, followed by either "cfi-flash", "jedec-flash"
+ or "mtd-ram".
+ - reg : Address range(s) of the mtd chip(s)
It's possible to (optionally) define multiple "reg" tuples so that
- non-identical NOR chips can be described in one flash node.
- - bank-width : Width (in bytes) of the flash bank. Equal to the
+ non-identical chips can be described in one node.
+ - bank-width : Width (in bytes) of the bank. Equal to the
device width times the number of interleaved chips.
- - device-width : (optional) Width of a single flash chip. If
+ - device-width : (optional) Width of a single mtd chip. If
omitted, assumed to be equal to 'bank-width'.
- - #address-cells, #size-cells : Must be present if the flash has
+ - #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.
@@ -22,24 +23,24 @@ are defined:
- vendor-id : Contains the flash chip's vendor id (1 byte).
- device-id : Contains the flash chip's device id (1 byte).
-In addition to the information on the flash bank itself, the
+In addition to the information on the mtd bank itself, the
device tree may optionally contain additional information
-describing partitions of the flash address space. This can be
+describing partitions of the address space. This can be
used on platforms which have strong conventions about which
-portions of the flash are used for what purposes, but which don't
+portions of a flash are used for what purposes, but which don't
use an on-flash partition table such as RedBoot.
-Each partition is represented as a sub-node of the flash device.
+Each partition is represented as a sub-node of the mtd device.
Each node's name represents the name of the corresponding
-partition of the flash device.
+partition of the mtd device.
Flash partitions
- - reg : The partition's offset and size within the flash bank.
- - label : (optional) The label / name for this flash partition.
+ - reg : The partition's offset and size within the mtd bank.
+ - label : (optional) The label / name for this partition.
If omitted, the label is taken from the node name (excluding
the unit address).
- read-only : (optional) This parameter, if present, is a hint to
- Linux that this flash partition should only be mounted
+ Linux that this partition should only be mounted
read-only. This is usually used for flash partitions
containing early-boot firmware images or data which should not
be clobbered.
@@ -78,3 +79,12 @@ Here an example with multiple "reg" tuples:
reg = <0 0x04000000>;
};
};
+
+An example using SRAM:
+
+ sram@2,0 {
+ compatible = "samsung,k6f1616u6a", "mtd-ram";
+ reg = <2 0 0x00200000>;
+ bank-width = <2>;
+ };
+

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