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Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/powerpc/booting-without-of.txt | 92 |
1 files changed, 58 insertions, 34 deletions
diff --git a/Documentation/powerpc/booting-without-of.txt b/Documentation/powerpc/booting-without-of.txt index 76733a3962f..20e0e6cb034 100644 --- a/Documentation/powerpc/booting-without-of.txt +++ b/Documentation/powerpc/booting-without-of.txt @@ -50,7 +50,7 @@ Table of Contents g) Freescale SOC SEC Security Engines h) Board Control and Status (BCSR) i) Freescale QUICC Engine module (QE) - j) Flash chip nodes + j) CFI or JEDEC memory-mapped NOR flash k) Global Utilities Block VII - Specifying interrupt information for devices @@ -1757,45 +1757,69 @@ platforms are moved over to use the flattened-device-tree model. }; }; - j) Flash chip nodes + j) CFI or JEDEC memory-mapped NOR flash Flash chips (Memory Technology Devices) are often used for solid state file systems on embedded devices. - Required properties: + - compatible : should contain the specific model of flash chip(s) + used, if known, followed by either "cfi-flash" or "jedec-flash" + - reg : Address range of the flash chip + - bank-width : Width (in bytes) of the flash bank. Equal to the + device width times the number of interleaved chips. + - device-width : (optional) Width of a single flash chip. If + omitted, assumed to be equal to 'bank-width'. + - #address-cells, #size-cells : Must be present if the flash has + sub-nodes representing partitions (see below). In this case + both #address-cells and #size-cells must be equal to 1. + + 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). + + In addition to the information on the flash bank itself, the + device tree may optionally contain additional information + describing partitions of the flash 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 + use an on-flash partition table such as RedBoot. + + Each partition is represented as a sub-node of the flash device. + Each node's name represents the name of the corresponding + partition of the flash device. + + Flash partitions + - reg : The partition's offset and size within the flash bank. + - label : (optional) The label / name for this flash 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 + read-only. This is usually used for flash partitions + containing early-boot firmware images or data which should not + be clobbered. - - device_type : has to be "rom" - - compatible : Should specify what this flash device is compatible with. - Currently, this is most likely to be "direct-mapped" (which - corresponds to the MTD physmap mapping driver). - - reg : Offset and length of the register set (or memory mapping) for - the device. - - bank-width : Width of the flash data bus in bytes. Required - for the NOR flashes (compatible == "direct-mapped" and others) ONLY. - - Recommended properties : - - - partitions : Several pairs of 32-bit values where the first value is - partition's offset from the start of the device and the second one is - partition size in bytes with LSB used to signify a read only - partition (so, the partition size should always be an even number). - - partition-names : The list of concatenated zero terminated strings - representing the partition names. - - probe-type : The type of probe which should be done for the chip - (JEDEC vs CFI actually). Valid ONLY for NOR flashes. - - Example: + Example: - flash@ff000000 { - device_type = "rom"; - compatible = "direct-mapped"; - probe-type = "CFI"; - reg = <ff000000 01000000>; - bank-width = <4>; - partitions = <00000000 00f80000 - 00f80000 00080001>; - partition-names = "fs\0firmware"; - }; + 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; + }; + }; k) Global Utilities Block |