[PATCH 6/6] mtd: spi-nand: Support common SPI NAND devices

[Qi Wang 王起 (qiwang)]

Hi Ezequiel, Brian

> +
> +static struct nand_ecclayout ecc_layout_gd5f = {
> +	.eccbytes = 128,
> +	.eccpos = {
> +		128, 129, 130, 131, 132, 133, 134, 135,
> +		136, 137, 138, 139, 140, 141, 142, 143,
> +		144, 145, 146, 147, 148, 149, 150, 151,
> +		152, 153, 154, 155, 156, 157, 158, 159,
> +		160, 161, 162, 163, 164, 165, 166, 167,
> +		168, 169, 170, 171, 172, 173, 174, 175,
> +		176, 177, 178, 179, 180, 181, 182, 183,
> +		184, 185, 186, 187, 188, 189, 190, 191,
> +		192, 193, 194, 195, 196, 197, 198, 199,
> +		200, 201, 202, 203, 204, 205, 206, 207,
> +		208, 209, 210, 211, 212, 213, 214, 215,
> +		216, 217, 218, 219, 220, 221, 222, 223,
> +		224, 225, 226, 227, 228, 229, 230, 231,
> +		232, 233, 234, 235, 236, 237, 238, 239,
> +		240, 241, 242, 243, 244, 245, 246, 247,
> +		248, 249, 250, 251, 252, 253, 254, 255
> +	},
> +	.oobfree = { {1, 127} }
> +};
> +
> +static struct nand_ecclayout ecc_layout_mt29f = {
> +	.eccbytes = 32,
> +	.eccpos = {
> +		8, 9, 10, 11, 12, 13, 14, 15,
> +		24, 25, 26, 27, 28, 29, 30, 31,
> +		40, 41, 42, 43, 44, 45, 46, 47,
> +		56, 57, 58, 59, 60, 61, 62, 63,
> +	 },
> +};
> +

As they are using On die ecc, oob layout definition is defined by SPI NAND vendors. 
Part of oob is protected by ecc, and the rest is unprotect.
I am thinking if we can define a variable to indicate the range, what is protect, 
and what is unprotect. 
This would be very useful for filesystem, which want to write data into OOB.

For example, Jffs2 program clean marker data to oob first when format operation, 
then will program main data into NAND flash main area when normal write operation. 
That mean JFFS2 can only store clean marker into unprotect area of oob. 
But for YAFFS2, it program main data and spare area data together into NAND flash, then
YAFFS2 can store data into protect area of OOB.
How do you think?

Thanks