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mtd: maps: add mtd-ram support to physmap_of

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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 Dreß <albrecht.dress@arcor.de>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
This commit is contained in:
Wolfram Sang 2009-07-17 14:39:23 +02:00 committed by David Woodhouse
parent 223cf6c3b5
commit fc28c39f0e
2 changed files with 30 additions and 16 deletions
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42
Documentation/powerpc/dts-bindings/mtd-physmap.txt
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@ -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 Flash chips (Memory Technology Devices) are often used for solid state
file systems on embedded devices. file systems on embedded devices.
- compatible : should contain the specific model of flash chip(s) - compatible : should contain the specific model of mtd chip(s)
used, if known, followed by either "cfi-flash" or "jedec-flash" used, if known, followed by either "cfi-flash", "jedec-flash"
- reg : Address range(s) of the flash chip(s) or "mtd-ram".
- reg : Address range(s) of the mtd chip(s)
It's possible to (optionally) define multiple "reg" tuples so that It's possible to (optionally) define multiple "reg" tuples so that
non-identical NOR chips can be described in one flash node. non-identical chips can be described in one node.
- bank-width : Width (in bytes) of the flash bank. Equal to the - bank-width : Width (in bytes) of the bank. Equal to the
device width times the number of interleaved chips. 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'. 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 sub-nodes representing partitions (see below). In this case
both #address-cells and #size-cells must be equal to 1. 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). - vendor-id : Contains the flash chip's vendor id (1 byte).
- device-id : Contains the flash chip's device 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 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 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. 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 Each node's name represents the name of the corresponding
partition of the flash device. partition of the mtd device.
Flash partitions Flash partitions
- reg : The partition's offset and size within the flash bank. - reg : The partition's offset and size within the mtd bank.
- label : (optional) The label / name for this flash partition. - label : (optional) The label / name for this partition.
If omitted, the label is taken from the node name (excluding If omitted, the label is taken from the node name (excluding
the unit address). the unit address).
- read-only : (optional) This parameter, if present, is a hint to - 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 read-only. This is usually used for flash partitions
containing early-boot firmware images or data which should not containing early-boot firmware images or data which should not
be clobbered. be clobbered.
@ -78,3 +79,12 @@ Here an example with multiple "reg" tuples:
reg = <0 0x04000000>; reg = <0 0x04000000>;
}; };
}; };
An example using SRAM:
sram@2,0 {
compatible = "samsung,k6f1616u6a", "mtd-ram";
reg = <2 0 0x00200000>;
bank-width = <2>;
};

4
drivers/mtd/maps/physmap_of.c
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@ -361,6 +361,10 @@ static struct of_device_id of_flash_match[] = {
.compatible = "jedec-flash", .compatible = "jedec-flash",
.data = (void *)"jedec_probe", .data = (void *)"jedec_probe",
}, },
{
.compatible = "mtd-ram",
.data = (void *)"map_ram",
},
{ {
.type = "rom", .type = "rom",
.compatible = "direct-mapped" .compatible = "direct-mapped"