About Kernel Documentation Linux Kernel Contact Linux Resources Linux Blog

Documentation / devicetree / bindings / mtd / mtd-physmap.txt




Custom Search

Based on kernel version 4.0. Page generated on 2015-04-14 21:21 EST.

1	CFI or JEDEC memory-mapped NOR flash, MTD-RAM (NVRAM...)
2	
3	Flash chips (Memory Technology Devices) are often used for solid state
4	file systems on embedded devices.
5	
6	 - compatible : should contain the specific model of mtd chip(s)
7	   used, if known, followed by either "cfi-flash", "jedec-flash",
8	   "mtd-ram" or "mtd-rom".
9	 - reg : Address range(s) of the mtd chip(s)
10	   It's possible to (optionally) define multiple "reg" tuples so that
11	   non-identical chips can be described in one node.
12	 - bank-width : Width (in bytes) of the bank.  Equal to the
13	   device width times the number of interleaved chips.
14	 - device-width : (optional) Width of a single mtd chip.  If
15	   omitted, assumed to be equal to 'bank-width'.
16	 - #address-cells, #size-cells : Must be present if the device has
17	   sub-nodes representing partitions (see below).  In this case
18	   both #address-cells and #size-cells must be equal to 1.
19	 - no-unaligned-direct-access: boolean to disable the default direct
20	   mapping of the flash.
21	   On some platforms (e.g. MPC5200) a direct 1:1 mapping may cause
22	   problems with JFFS2 usage, as the local bus (LPB) doesn't support
23	   unaligned accesses as implemented in the JFFS2 code via memcpy().
24	   By defining "no-unaligned-direct-access", the flash will not be
25	   exposed directly to the MTD users (e.g. JFFS2) any more.
26	 - linux,mtd-name: allow to specify the mtd name for retro capability with
27	   physmap-flash drivers as boot loader pass the mtd partition via the old
28	   device name physmap-flash.
29	 - use-advanced-sector-protection: boolean to enable support for the
30	   advanced sector protection (Spansion: PPB - Persistent Protection
31	   Bits) locking.
32	
33	For JEDEC compatible devices, the following additional properties
34	are defined:
35	
36	 - vendor-id : Contains the flash chip's vendor id (1 byte).
37	 - device-id : Contains the flash chip's device id (1 byte).
38	
39	For ROM compatible devices (and ROM fallback from cfi-flash), the following
40	additional (optional) property is defined:
41	
42	 - erase-size : The chip's physical erase block size in bytes.
43	
44	The device tree may optionally contain sub-nodes describing partitions of the
45	address space. See partition.txt for more detail.
46	
47	Example:
48	
49		flash@ff000000 {
50			compatible = "amd,am29lv128ml", "cfi-flash";
51			reg = <ff000000 01000000>;
52			bank-width = <4>;
53			device-width = <1>;
54			#address-cells = <1>;
55			#size-cells = <1>;
56			fs@0 {
57				label = "fs";
58				reg = <0 f80000>;
59			};
60			firmware@f80000 {
61				label ="firmware";
62				reg = <f80000 80000>;
63				read-only;
64			};
65		};
66	
67	Here an example with multiple "reg" tuples:
68	
69		flash@f0000000,0 {
70			#address-cells = <1>;
71			#size-cells = <1>;
72			compatible = "intel,PC48F4400P0VB", "cfi-flash";
73			reg = <0 0x00000000 0x02000000
74			       0 0x02000000 0x02000000>;
75			bank-width = <2>;
76			partition@0 {
77				label = "test-part1";
78				reg = <0 0x04000000>;
79			};
80		};
81	
82	An example using SRAM:
83	
84		sram@2,0 {
85			compatible = "samsung,k6f1616u6a", "mtd-ram";
86			reg = <2 0 0x00200000>;
87			bank-width = <2>;
88		};
Hide Line Numbers
About Kernel Documentation Linux Kernel Contact Linux Resources Linux Blog

Information is copyright its respective author. All material is available from the Linux Kernel Source distributed under a GPL License. This page is provided as a free service by mjmwired.net.