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Diffstat (limited to 'Documentation/devicetree/bindings/mtd/gpmc-nand.txt')
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diff --git a/Documentation/devicetree/bindings/mtd/gpmc-nand.txt b/Documentation/devicetree/bindings/mtd/gpmc-nand.txt deleted file mode 100644 index c459f169a904..000000000000 --- a/Documentation/devicetree/bindings/mtd/gpmc-nand.txt +++ /dev/null @@ -1,147 +0,0 @@ -Device tree bindings for GPMC connected NANDs - -GPMC connected NAND (found on OMAP boards) are represented as child nodes of -the GPMC controller with a name of "nand". - -All timing relevant properties as well as generic gpmc child properties are -explained in a separate documents - please refer to -Documentation/devicetree/bindings/memory-controllers/omap-gpmc.txt - -For NAND specific properties such as ECC modes or bus width, please refer to -Documentation/devicetree/bindings/mtd/nand-controller.yaml - - -Required properties: - - - compatible: "ti,omap2-nand" - - reg: range id (CS number), base offset and length of the - NAND I/O space - - interrupts: Two interrupt specifiers, one for fifoevent, one for termcount. - -Optional properties: - - - nand-bus-width: Set this numeric value to 16 if the hardware - is wired that way. If not specified, a bus - width of 8 is assumed. - - - ti,nand-ecc-opt: A string setting the ECC layout to use. One of: - "sw" 1-bit Hamming ecc code via software - "hw" <deprecated> use "ham1" instead - "hw-romcode" <deprecated> use "ham1" instead - "ham1" 1-bit Hamming ecc code - "bch4" 4-bit BCH ecc code - "bch8" 8-bit BCH ecc code - "bch16" 16-bit BCH ECC code - Refer below "How to select correct ECC scheme for your device ?" - - - ti,nand-xfer-type: A string setting the data transfer type. One of: - - "prefetch-polled" Prefetch polled mode (default) - "polled" Polled mode, without prefetch - "prefetch-dma" Prefetch enabled DMA mode - "prefetch-irq" Prefetch enabled irq mode - - - elm_id: <deprecated> use "ti,elm-id" instead - - ti,elm-id: Specifies phandle of the ELM devicetree node. - ELM is an on-chip hardware engine on TI SoC which is used for - locating ECC errors for BCHx algorithms. SoC devices which have - ELM hardware engines should specify this device node in .dtsi - Using ELM for ECC error correction frees some CPU cycles. - - rb-gpios: GPIO specifier for the ready/busy# pin. - -For inline partition table parsing (optional): - - - #address-cells: should be set to 1 - - #size-cells: should be set to 1 - -Example for an AM33xx board: - - gpmc: gpmc@50000000 { - compatible = "ti,am3352-gpmc"; - ti,hwmods = "gpmc"; - reg = <0x50000000 0x36c>; - interrupts = <100>; - gpmc,num-cs = <8>; - gpmc,num-waitpins = <2>; - #address-cells = <2>; - #size-cells = <1>; - ranges = <0 0 0x08000000 0x1000000>; /* CS0 space, 16MB */ - elm_id = <&elm>; - interrupt-controller; - #interrupt-cells = <2>; - - nand@0,0 { - compatible = "ti,omap2-nand"; - reg = <0 0 4>; /* CS0, offset 0, NAND I/O window 4 */ - interrupt-parent = <&gpmc>; - interrupts = <0 IRQ_TYPE_NONE>, <1 IRQ_TYPE NONE>; - nand-bus-width = <16>; - ti,nand-ecc-opt = "bch8"; - ti,nand-xfer-type = "polled"; - rb-gpios = <&gpmc 0 GPIO_ACTIVE_HIGH>; /* gpmc_wait0 */ - - gpmc,sync-clk-ps = <0>; - gpmc,cs-on-ns = <0>; - gpmc,cs-rd-off-ns = <44>; - gpmc,cs-wr-off-ns = <44>; - gpmc,adv-on-ns = <6>; - gpmc,adv-rd-off-ns = <34>; - gpmc,adv-wr-off-ns = <44>; - gpmc,we-off-ns = <40>; - gpmc,oe-off-ns = <54>; - gpmc,access-ns = <64>; - gpmc,rd-cycle-ns = <82>; - gpmc,wr-cycle-ns = <82>; - gpmc,wr-access-ns = <40>; - gpmc,wr-data-mux-bus-ns = <0>; - - #address-cells = <1>; - #size-cells = <1>; - - /* partitions go here */ - }; - }; - -How to select correct ECC scheme for your device ? --------------------------------------------------- -Higher ECC scheme usually means better protection against bit-flips and -increased system lifetime. However, selection of ECC scheme is dependent -on various other factors also like; - -(1) support of built in hardware engines. - Some legacy OMAP SoC do not have ELM harware engine, so those SoC cannot - support ecc-schemes with hardware error-correction (BCHx_HW). However - such SoC can use ecc-schemes with software library for error-correction - (BCHx_HW_DETECTION_SW). The error correction capability with software - library remains equivalent to their hardware counter-part, but there is - slight CPU penalty when too many bit-flips are detected during reads. - -(2) Device parameters like OOBSIZE. - Other factor which governs the selection of ecc-scheme is oob-size. - Higher ECC schemes require more OOB/Spare area to store ECC syndrome, - so the device should have enough free bytes available its OOB/Spare - area to accommodate ECC for entire page. In general following expression - helps in determining if given device can accommodate ECC syndrome: - "2 + (PAGESIZE / 512) * ECC_BYTES" <= OOBSIZE" - where - OOBSIZE number of bytes in OOB/spare area - PAGESIZE number of bytes in main-area of device page - ECC_BYTES number of ECC bytes generated to protect - 512 bytes of data, which is: - '3' for HAM1_xx ecc schemes - '7' for BCH4_xx ecc schemes - '14' for BCH8_xx ecc schemes - '26' for BCH16_xx ecc schemes - - Example(a): For a device with PAGESIZE = 2048 and OOBSIZE = 64 and - trying to use BCH16 (ECC_BYTES=26) ecc-scheme. - Number of ECC bytes per page = (2 + (2048 / 512) * 26) = 106 B - which is greater than capacity of NAND device (OOBSIZE=64) - Hence, BCH16 cannot be supported on given device. But it can - probably use lower ecc-schemes like BCH8. - - Example(b): For a device with PAGESIZE = 2048 and OOBSIZE = 128 and - trying to use BCH16 (ECC_BYTES=26) ecc-scheme. - Number of ECC bytes per page = (2 + (2048 / 512) * 26) = 106 B - which can be accommodated in the OOB/Spare area of this device - (OOBSIZE=128). So this device can use BCH16 ecc-scheme. |