Re: [PATCH v2 2/8] MTD: xway: add some more documentation

[Boris Brezillon <boris.brezillon@free-electrons.com>]

On Sat, 18 Jun 2016 21:14:06 +0200
Hauke Mehrtens <hauke@hauke-m.de> wrote:

> This adds some register documentation which should make it easier to
> understand how this controller works.
> 
> Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
> ---
>  drivers/mtd/nand/xway_nand.c | 12 +++++++++++-
>  1 file changed, 11 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mtd/nand/xway_nand.c b/drivers/mtd/nand/xway_nand.c
> index 867a636..2889e48 100644
> --- a/drivers/mtd/nand/xway_nand.c
> +++ b/drivers/mtd/nand/xway_nand.c
> @@ -20,10 +20,20 @@
>  #define EBU_NAND_ECC0		0xB8
>  #define EBU_NAND_ECC_AC		0xBC
>  
> -/* nand commands */
> +/*
> + * nand commands
> + * The pins of the NAND chip are selected based on the address bits of the
> + * "register" read and write. There are no special registers, but an
> + * address range and the lower address bits are used to activate the
> + * correct line. For example when the bit (1 << 2) is set in the address
> + * the ALE pin will be activated.
> + */
>  #define NAND_CMD_ALE		(1 << 2)
>  #define NAND_CMD_CLE		(1 << 3)
>  #define NAND_CMD_CS		(1 << 4)
> +#define NAND_CMD_SE		(1 << 5)
> +#define NAND_CMD_WP		(1 << 6)
> +#define NAND_CMD_PRE		(1 << 7)

I see what _WP means, but what about _PRE and _SE? Can you document
these features?

>  #define NAND_WRITE_CMD_RESET	0xff
>  #define NAND_WRITE_CMD		(NAND_CMD_CS | NAND_CMD_CLE)
>  #define NAND_WRITE_ADDR		(NAND_CMD_CS | NAND_CMD_ALE)