[U-Boot] mmc_write.c: Make mmc_berase do 32bit safe 64bit math

[Hans de Goede]

Hi,

On 12-06-15 02:53, Tom Rini wrote:
> We want to see if the requested start or total block count are
> unaligned.  We discard the whole numbers and only care about the
> remainder.  Update the code to use div_u64_rem here and add a comment.
>
> Cc: Hans de Goede <hdegoede at redhat.com>
> Cc: Pantelis Antoniou <pantelis.antoniou at konsulko.com>
> Cc: Bernhard Nortmann <bernhard.nortmann at web.de>
> Reported-by: Simon Glass <sjg at chromium.org>
> Signed-off-by: Tom Rini <trini at konsulko.com>
> Tested-by: Bernhard Nortmann <bernhard.nortmann at web.de>

Thanks for this, looks good to me:

Reviewed-by: Hans de Goede <hdegoede at redhat.com>

Regards,

Hans

> ---
>   drivers/mmc/mmc_write.c |   12 +++++++++++-
>   1 file changed, 11 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mmc/mmc_write.c b/drivers/mmc/mmc_write.c
> index 3db9669..7aea7e9 100644
> --- a/drivers/mmc/mmc_write.c
> +++ b/drivers/mmc/mmc_write.c
> @@ -10,6 +10,8 @@
>   #include <config.h>
>   #include <common.h>
>   #include <part.h>
> +#include <div64.h>
> +#include <linux/math64.h>
>   #include "mmc_private.h"
>
>   static ulong mmc_erase_t(struct mmc *mmc, ulong start, lbaint_t blkcnt)
> @@ -66,6 +68,7 @@ err_out:
>   unsigned long mmc_berase(int dev_num, lbaint_t start, lbaint_t blkcnt)
>   {
>   	int err = 0;
> +	u32 start_rem, blkcnt_rem;
>   	struct mmc *mmc = find_mmc_device(dev_num);
>   	lbaint_t blk = 0, blk_r = 0;
>   	int timeout = 1000;
> @@ -73,7 +76,14 @@ unsigned long mmc_berase(int dev_num, lbaint_t start, lbaint_t blkcnt)
>   	if (!mmc)
>   		return -1;
>
> -	if ((start % mmc->erase_grp_size) || (blkcnt % mmc->erase_grp_size))
> +	/*
> +	 * We want to see if the requested start or total block count are
> +	 * unaligned.  We discard the whole numbers and only care about the
> +	 * remainder.
> +	 */
> +	err = div_u64_rem(start, mmc->erase_grp_size, &start_rem);
> +	err = div_u64_rem(blkcnt, mmc->erase_grp_size, &blkcnt_rem);
> +	if (start_rem || blkcnt_rem)
>   		printf("\n\nCaution! Your devices Erase group is 0x%x\n"
>   		       "The erase range would be change to "
>   		       "0x" LBAF "~0x" LBAF "\n\n",
>