Adding upstream version 5.10.209.upstream/5.10.209upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 147 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/mtd/gpmc-nand.txt b/Documentation/devicetree/bindings/mtd/gpmc-nand.txt
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+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.