[U-Boot] [PATCHv4 2/7] nand_spl_simple: Add a simple NAND read function

[Heiko Schocher]

Hello Ladislav,

Am 17.01.2016 um 04:12 schrieb Ladislav Michl:
> From: Thomas Gleixner <tglx at linutronix.de>
>
> To support UBI in SPL we need a simple NAND read function. Add one to
> nand_spl_simple and keep it as simple as it goes.
>
> Signed-off-by: Thomas Gleixner <tglx at linutronix.de>
> Signed-off-by: Ladislav Michl <ladis at linux-mips.org>
> Acked-by: Scott Wood <oss at buserror.net>
> Reviewed-by: Tom Rini <trini at konsulko.com>
> ---
> Changes in v3:
> - Rename nand_spl_read_flash to nand_spl_read_block and optimize it.
>
>   drivers/mtd/nand/nand_spl_simple.c | 62 ++++++++++++++++++++++++++++++++++++++
>   include/nand.h                     |  1 +
>   2 files changed, 63 insertions(+)

Reviewed-by: Heiko Schocher <hs at denx.de>

bye,
Heiko
>
> diff --git a/drivers/mtd/nand/nand_spl_simple.c b/drivers/mtd/nand/nand_spl_simple.c
> index e69f662..cf80903 100644
> --- a/drivers/mtd/nand/nand_spl_simple.c
> +++ b/drivers/mtd/nand/nand_spl_simple.c
> @@ -209,6 +209,68 @@ static int nand_read_page(int block, int page, void *dst)
>   }
>   #endif
>
> +#ifdef CONFIG_SPL_UBI
> +/*
> + * Temporary storage for non NAND page aligned and non NAND page sized
> + * reads. Note: This does not support runtime detected FLASH yet, but
> + * that should be reasonably easy to fix by making the buffer large
> + * enough :)
> + */
> +static u8 scratch_buf[CONFIG_SYS_NAND_PAGE_SIZE];
> +
> +/**
> + * nand_spl_read_block - Read data from physical eraseblock into a buffer
> + * @block:	Number of the physical eraseblock
> + * @offset:	Data offset from the start of @peb
> + * @len:	Data size to read
> + * @dst:	Address of the destination buffer
> + *
> + * This could be further optimized if we'd have a subpage read
> + * function in the simple code. On NAND which allows subpage reads
> + * this would spare quite some time to readout e.g. the VID header of
> + * UBI.
> + *
> + * Notes:
> + *	@offset + @len are not allowed to be larger than a physical
> + *	erase block. No sanity check done for simplicity reasons.
> + *
> + * To support runtime detected flash this needs to be extended by
> + * information about the actual flash geometry, but thats beyond the
> + * scope of this effort and for most applications where fast boot is
> + * required it is not an issue anyway.
> + */
> +int nand_spl_read_block(int block, int offset, int len, void *dst)
> +{
> +	int page, read;
> +
> +	/* Calculate the page number */
> +	page = offset / CONFIG_SYS_NAND_PAGE_SIZE;
> +
> +	/* Offset to the start of a flash page */
> +	offset = offset % CONFIG_SYS_NAND_PAGE_SIZE;
> +
> +	while (len) {
> +		/*
> +		 * Non page aligned reads go to the scratch buffer.
> +		 * Page aligned reads go directly to the destination.
> +		 */
> +		if (offset || len < CONFIG_SYS_NAND_PAGE_SIZE) {
> +			nand_read_page(block, page, scratch_buf);
> +			read = min(len, CONFIG_SYS_NAND_PAGE_SIZE - offset);
> +			memcpy(dst, scratch_buf + offset, read);
> +			offset = 0;
> +		} else {
> +			nand_read_page(block, page, dst);
> +			read = CONFIG_SYS_NAND_PAGE_SIZE;
> +		}
> +		page++;
> +		len -= read;
> +		dst += read;
> +	}
> +	return 0;
> +}
> +#endif
> +
>   int nand_spl_load_image(uint32_t offs, unsigned int size, void *dst)
>   {
>   	unsigned int block, lastblock;
> diff --git a/include/nand.h b/include/nand.h
> index d2a53ab..2f9a1ec 100644
> --- a/include/nand.h
> +++ b/include/nand.h
> @@ -124,6 +124,7 @@ int nand_unlock(nand_info_t *meminfo, loff_t start, size_t length,
>   int nand_get_lock_status(nand_info_t *meminfo, loff_t offset);
>
>   int nand_spl_load_image(uint32_t offs, unsigned int size, void *dst);
> +int nand_spl_read_block(int block, int offset, int len, void *dst);
>   void nand_deselect(void);
>
>   #ifdef CONFIG_SYS_NAND_SELECT_DEVICE
>

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