Commit fc28c39f authored by Wolfram Sang's avatar Wolfram Sang Committed by David Woodhouse
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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: default avatarWolfram 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: default avatarGrant Likely <grant.likely@secretlab.ca>
Signed-off-by: default avatarDavid Woodhouse <David.Woodhouse@intel.com>
parent 223cf6c3
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>;
};
......@@ -361,6 +361,10 @@ static struct of_device_id of_flash_match[] = {
.compatible = "jedec-flash",
.data = (void *)"jedec_probe",
},
{
.compatible = "mtd-ram",
.data = (void *)"map_ram",
},
{
.type = "rom",
.compatible = "direct-mapped"
......
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