Documentation: devicetree: add binding doc for Broadcom NAND controller

Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
This commit is contained in:
Brian Norris 2015-03-06 11:36:21 -08:00
parent 073db4a51e
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* Broadcom STB NAND Controller
The Broadcom Set-Top Box NAND controller supports low-level access to raw NAND
flash chips. It has a memory-mapped register interface for both control
registers and for its data input/output buffer. On some SoCs, this controller is
paired with a custom DMA engine (inventively named "Flash DMA") which supports
basic PROGRAM and READ functions, among other features.
This controller was originally designed for STB SoCs (BCM7xxx) but is now
available on a variety of Broadcom SoCs, including some BCM3xxx, BCM63xx, and
iProc/Cygnus. Its history includes several similar (but not fully register
compatible) versions.
Required properties:
- compatible : should contain "brcm,brcmnand" and an appropriate version
compatibility string, like "brcm,brcmnand-v7.0"
Possible values:
brcm,brcmnand-v4.0
brcm,brcmnand-v5.0
brcm,brcmnand-v6.0
brcm,brcmnand-v6.1
brcm,brcmnand-v7.0
brcm,brcmnand-v7.1
brcm,brcmnand
- reg : the register start and length for NAND register region.
(optional) Flash DMA register range (if present)
(optional) NAND flash cache range (if at non-standard offset)
- reg-names : a list of the names corresponding to the previous register
ranges. Should contain "nand" and (optionally)
"flash-dma" and/or "nand-cache".
- interrupts : The NAND CTLRDY interrupt and (if Flash DMA is available)
FLASH_DMA_DONE
- interrupt-names : May be "nand_ctlrdy" or "flash_dma_done"
- interrupt-parent : See standard interrupt bindings
- #address-cells : <1> - subnodes give the chip-select number
- #size-cells : <0>
Optional properties:
- brcm,nand-has-wp : Some versions of this IP include a write-protect
(WP) control bit. It is always available on >=
v7.0. Use this property to describe the rare
earlier versions of this core that include WP
* NAND chip-select
Each controller (compatible: "brcm,brcmnand") may contain one or more subnodes
to represent enabled chip-selects which (may) contain NAND flash chips. Their
properties are as follows.
Required properties:
- compatible : should contain "brcm,nandcs"
- reg : a single integer representing the chip-select
number (e.g., 0, 1, 2, etc.)
- #address-cells : see partition.txt
- #size-cells : see partition.txt
- nand-ecc-strength : see nand.txt
- nand-ecc-step-size : must be 512 or 1024. See nand.txt
Optional properties:
- nand-on-flash-bbt : boolean, to enable the on-flash BBT for this
chip-select. See nand.txt
- brcm,nand-oob-sector-size : integer, to denote the spare area sector size
expected for the ECC layout in use. This size, in
addition to the strength and step-size,
determines how the hardware BCH engine will lay
out the parity bytes it stores on the flash.
This property can be automatically determined by
the flash geometry (particularly the NAND page
and OOB size) in many cases, but when booting
from NAND, the boot controller has only a limited
number of available options for its default ECC
layout.
Each nandcs device node may optionally contain sub-nodes describing the flash
partition mapping. See partition.txt for more detail.
Example:
nand@f0442800 {
compatible = "brcm,brcmnand-v7.0", "brcm,brcmnand";
reg = <0xF0442800 0x600>,
<0xF0443000 0x100>;
reg-names = "nand", "flash-dma";
interrupt-parent = <&hif_intr2_intc>;
interrupts = <24>, <4>;
#address-cells = <1>;
#size-cells = <0>;
nandcs@1 {
compatible = "brcm,nandcs";
reg = <1>; // Chip select 1
nand-on-flash-bbt;
nand-ecc-strength = <12>;
nand-ecc-step-size = <512>;
// Partitions
#address-cells = <1>; // <2>, for 64-bit offset
#size-cells = <1>; // <2>, for 64-bit length
flash0.rootfs@0 {
reg = <0 0x10000000>;
};
flash0@0 {
reg = <0 0>; // MTDPART_SIZ_FULL
};
flash0.kernel@10000000 {
reg = <0x10000000 0x400000>;
};
};
};