2012-12-14 18:36:44 +08:00
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Device tree bindings for GPMC connected NANDs
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GPMC connected NAND (found on OMAP boards) are represented as child nodes of
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the GPMC controller with a name of "nand".
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All timing relevant properties as well as generic gpmc child properties are
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explained in a separate documents - please refer to
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Documentation/devicetree/bindings/bus/ti-gpmc.txt
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For NAND specific properties such as ECC modes or bus width, please refer to
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Documentation/devicetree/bindings/mtd/nand.txt
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Required properties:
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- reg: The CS line the peripheral is connected to
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Optional properties:
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- nand-bus-width: Set this numeric value to 16 if the hardware
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is wired that way. If not specified, a bus
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width of 8 is assumed.
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- ti,nand-ecc-opt: A string setting the ECC layout to use. One of:
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"sw" Software method (default)
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"hw" Hardware method
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"hw-romcode" gpmc hamming mode method & romcode layout
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"bch4" 4-bit BCH ecc code
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"bch8" 8-bit BCH ecc code
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2013-04-20 04:08:28 +08:00
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- ti,nand-xfer-type: A string setting the data transfer type. One of:
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"prefetch-polled" Prefetch polled mode (default)
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"polled" Polled mode, without prefetch
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"prefetch-dma" Prefetch enabled sDMA mode
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"prefetch-irq" Prefetch enabled irq mode
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ARM: OMAP2+: cleaned-up DT support of various ECC schemes
OMAP NAND driver support multiple ECC scheme, which can used in different
flavours, depending on in-build Hardware engines present on SoC.
This patch updates following in DT bindings related to sectionion of ecc-schemes
- ti,elm-id: replaces elm_id (maintains backward compatibility)
- ti,nand-ecc-opts: selection of h/w or s/w implementation of an ecc-scheme
depends on ti,elm-id. (supported values ham1, bch4, and bch8)
- maintain backward compatibility to deprecated DT bindings (sw, hw, hw-romcode)
Below table shows different flavours of ecc-schemes supported by OMAP devices
+---------------------------------------+---------------+---------------+
| ECC scheme |ECC calculation|Error detection|
+---------------------------------------+---------------+---------------+
|OMAP_ECC_HAM1_CODE_HW |H/W (GPMC) |S/W |
+---------------------------------------+---------------+---------------+
|OMAP_ECC_BCH8_CODE_HW_DETECTION_SW |H/W (GPMC) |S/W |
|(requires CONFIG_MTD_NAND_ECC_BCH) | | |
+---------------------------------------+---------------+---------------+
|OMAP_ECC_BCH8_CODE_HW |H/W (GPMC) |H/W (ELM) |
|(requires CONFIG_MTD_NAND_OMAP_BCH && | | |
| ti,elm-id in DT) | | |
+---------------------------------------+---------------+---------------+
To optimize footprint of omap2-nand driver, selection of some ECC schemes
also require enabling following Kconfigs, in addition to setting appropriate
DT bindings
- Kconfig:CONFIG_MTD_NAND_ECC_BCH error detection done in software
- Kconfig:CONFIG_MTD_NAND_OMAP_BCH error detection done by h/w engine
Signed-off-by: Pekon Gupta <pekon@ti.com>
Reviewed-by: Felipe Balbi <balbi@ti.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Tested-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
2013-10-24 20:50:17 +08:00
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- elm_id: <deprecated> use "ti,elm-id" instead
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- ti,elm-id: Specifies phandle of the ELM devicetree node.
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ELM is an on-chip hardware engine on TI SoC which is used for
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locating ECC errors for BCHx algorithms. SoC devices which have
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ELM hardware engines should specify this device node in .dtsi
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Using ELM for ECC error correction frees some CPU cycles.
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2013-01-18 12:57:46 +08:00
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2012-12-14 18:36:44 +08:00
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For inline partiton table parsing (optional):
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- #address-cells: should be set to 1
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- #size-cells: should be set to 1
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Example for an AM33xx board:
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gpmc: gpmc@50000000 {
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compatible = "ti,am3352-gpmc";
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ti,hwmods = "gpmc";
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reg = <0x50000000 0x1000000>;
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interrupts = <100>;
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gpmc,num-cs = <8>;
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gpmc,num-waitpins = <2>;
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#address-cells = <2>;
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#size-cells = <1>;
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ranges = <0 0 0x08000000 0x2000>; /* CS0: NAND */
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2013-01-18 12:57:46 +08:00
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elm_id = <&elm>;
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2012-12-14 18:36:44 +08:00
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nand@0,0 {
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reg = <0 0 0>; /* CS0, offset 0 */
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nand-bus-width = <16>;
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ti,nand-ecc-opt = "bch8";
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2013-04-20 04:08:28 +08:00
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ti,nand-xfer-type = "polled";
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2012-12-14 18:36:44 +08:00
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2013-04-10 00:37:40 +08:00
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gpmc,sync-clk-ps = <0>;
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gpmc,cs-on-ns = <0>;
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gpmc,cs-rd-off-ns = <44>;
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gpmc,cs-wr-off-ns = <44>;
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gpmc,adv-on-ns = <6>;
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gpmc,adv-rd-off-ns = <34>;
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gpmc,adv-wr-off-ns = <44>;
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gpmc,we-off-ns = <40>;
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gpmc,oe-off-ns = <54>;
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gpmc,access-ns = <64>;
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gpmc,rd-cycle-ns = <82>;
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gpmc,wr-cycle-ns = <82>;
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gpmc,wr-access-ns = <40>;
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gpmc,wr-data-mux-bus-ns = <0>;
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2012-12-14 18:36:44 +08:00
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#address-cells = <1>;
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#size-cells = <1>;
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/* partitions go here */
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};
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};
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