90 lines
2.9 KiB
Plaintext
90 lines
2.9 KiB
Plaintext
|
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 mtd chip(s)
|
||
|
|
used, if known, followed by either "cfi-flash", "jedec-flash",
|
||
|
|
"mtd-ram" or "mtd-rom".
|
||
|
|
- reg : Address range(s) of the mtd chip(s)
|
||
|
|
It's possible to (optionally) define multiple "reg" tuples so that
|
||
|
|
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 mtd chip. If
|
||
|
|
omitted, assumed to be equal to 'bank-width'.
|
||
|
|
- #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.
|
||
|
|
- linux,mtd-name: allow to specify the mtd name for retro capability with
|
||
|
|
physmap-flash drivers as boot loader pass the mtd partition via the old
|
||
|
|
device name physmap-flash.
|
||
|
|
- use-advanced-sector-protection: boolean to enable support for the
|
||
|
|
advanced sector protection (Spansion: PPB - Persistent Protection
|
||
|
|
Bits) locking.
|
||
|
|
|
||
|
|
For JEDEC compatible devices, the following additional properties
|
||
|
|
are defined:
|
||
|
|
|
||
|
|
- vendor-id : Contains the flash chip's vendor id (1 byte).
|
||
|
|
- device-id : Contains the flash chip's device id (1 byte).
|
||
|
|
|
||
|
|
For ROM compatible devices (and ROM fallback from cfi-flash), the following
|
||
|
|
additional (optional) property is defined:
|
||
|
|
|
||
|
|
- erase-size : The chip's physical erase block size in bytes.
|
||
|
|
|
||
|
|
The device tree may optionally contain sub-nodes describing partitions of the
|
||
|
|
address space. See partition.txt for more detail.
|
||
|
|
|
||
|
|
Example:
|
||
|
|
|
||
|
|
flash@ff000000 {
|
||
|
|
compatible = "amd,am29lv128ml", "cfi-flash";
|
||
|
|
reg = <ff000000 01000000>;
|
||
|
|
bank-width = <4>;
|
||
|
|
device-width = <1>;
|
||
|
|
#address-cells = <1>;
|
||
|
|
#size-cells = <1>;
|
||
|
|
fs@0 {
|
||
|
|
label = "fs";
|
||
|
|
reg = <0 f80000>;
|
||
|
|
};
|
||
|
|
firmware@f80000 {
|
||
|
|
label ="firmware";
|
||
|
|
reg = <f80000 80000>;
|
||
|
|
read-only;
|
||
|
|
};
|
||
|
|
};
|
||
|
|
|
||
|
|
Here an example with multiple "reg" tuples:
|
||
|
|
|
||
|
|
flash@f0000000,0 {
|
||
|
|
#address-cells = <1>;
|
||
|
|
#size-cells = <1>;
|
||
|
|
compatible = "intel,PC48F4400P0VB", "cfi-flash";
|
||
|
|
reg = <0 0x00000000 0x02000000
|
||
|
|
0 0x02000000 0x02000000>;
|
||
|
|
bank-width = <2>;
|
||
|
|
partition@0 {
|
||
|
|
label = "test-part1";
|
||
|
|
reg = <0 0x04000000>;
|
||
|
|
};
|
||
|
|
};
|
||
|
|
|
||
|
|
An example using SRAM:
|
||
|
|
|
||
|
|
sram@2,0 {
|
||
|
|
compatible = "samsung,k6f1616u6a", "mtd-ram";
|
||
|
|
reg = <2 0 0x00200000>;
|
||
|
|
bank-width = <2>;
|
||
|
|
};
|
||
|
|
|