Re: [PATCH v3 5/5] mmc: card: Add RPMB support in IOCTL interface

[shashidhar hiremath <shashidar1887@gmail.com>]

On Mon, Aug 6, 2012 at 8:42 PM, Loic Pallardy
<loic.pallardy-ext@stericsson.com> wrote:
>
> RPMB partition is accessing though /dev/block/mmcXrpmb device
> User callers can read and write entire data frame(s) as defined
> by JEDEC Standard JESD84-A441, using standard IOCTL interface.
>
> Signed-off-by: Alex Macro <alex.macro@stericsson.com>
> Signed-off-by: Loic Pallardy <loic.pallardy@stericsson.com>
> Acked-by: Linus Walleij <linus.walleij@linaro.org>
> Reviewed-by: Namjae Jeon <linkinjeon@gmail.com>
> ---
>  drivers/mmc/card/block.c | 64 ++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 64 insertions(+)
>
> diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
> index d8edb8d..a9e1f1f 100644
> --- a/drivers/mmc/card/block.c
> +++ b/drivers/mmc/card/block.c
> @@ -126,6 +126,10 @@ enum mmc_blk_status {
>  module_param(perdev_minors, int, 0444);
>  MODULE_PARM_DESC(perdev_minors, "Minors numbers to allocate per device");
>
> +static inline int mmc_blk_part_switch(struct mmc_card *card,
> +                                     struct mmc_blk_data *md);
> +static int get_card_status(struct mmc_card *card, u32 *status, int retries);
> +
>  static struct mmc_blk_data *mmc_blk_get(struct gendisk *disk)
>  {
>         struct mmc_blk_data *md;
> @@ -357,6 +361,38 @@ out:
>         return ERR_PTR(err);
>  }
>
> +static int ioctl_rpmb_card_status_poll(struct mmc_card *card, u32 *status,
> +                                      u32 retries_max)
> +{
> +       int err;
> +       u32 retry_count = 0;
> +
> +       if (!status || !retries_max)
> +               return -EINVAL;
> +
> +       do {
> +               err = get_card_status(card, status, 5);
> +               if (err)
> +                       break;
> +
> +               if (!R1_STATUS(*status) &&
> +                               (R1_CURRENT_STATE(*status) != R1_STATE_PRG))
> +                       break; /* RPMB programming operation complete */
> +
> +               /*
> +                * Rechedule to give the MMC device a chance to continue
> +                * processing the previous command without being polled too
> +                * frequently.
> +                */
> +               usleep_range(1000, 5000);
> +       } while (++retry_count < retries_max);
> +
> +       if (retry_count == retries_max)
> +               err = -EPERM;
> +
> +       return err;
> +}
> +
>  static int mmc_blk_ioctl_cmd(struct block_device *bdev,
>         struct mmc_ioc_cmd __user *ic_ptr)
>  {
> @@ -368,6 +404,8 @@ static int mmc_blk_ioctl_cmd(struct block_device *bdev,
>         struct mmc_request mrq = {NULL};
>         struct scatterlist sg;
>         int err;
> +       int is_rpmb = false;
> +       u32 status = 0;
>
>         /*
>          * The caller must have CAP_SYS_RAWIO, and must be calling this on the
> @@ -387,6 +425,9 @@ static int mmc_blk_ioctl_cmd(struct block_device *bdev,
>                 goto cmd_err;
>         }
>
> +       if (md->area_type & MMC_BLK_DATA_AREA_RPMB)
> +               is_rpmb = true;
> +
>         card = md->queue.card;
>         if (IS_ERR(card)) {
>                 err = PTR_ERR(card);
> @@ -437,12 +478,23 @@ static int mmc_blk_ioctl_cmd(struct block_device *bdev,
>
>         mmc_claim_host(card->host);
>
> +       err = mmc_blk_part_switch(card, md);
> +       if (err)
> +               goto cmd_rel_host;
> +
>         if (idata->ic.is_acmd) {
>                 err = mmc_app_cmd(card->host, card);
>                 if (err)
>                         goto cmd_rel_host;
>         }
>
> +       if (is_rpmb) {
> +               err = mmc_set_blockcount(card, data.blocks,
> +                       idata->ic.write_flag & (1 << 31));
> +               if (err)
> +                       goto cmd_rel_host;
> +       }
> +
>         mmc_wait_for_req(card->host, &mrq);
>
>         if (cmd.error) {
> @@ -478,6 +530,18 @@ static int mmc_blk_ioctl_cmd(struct block_device *bdev,
>                 }
>         }
>
> +       if (is_rpmb) {
> +               /*
> +                * Ensure RPMB command has completed by polling CMD13
> +                * "Send Status".
> +                */
> +               err = ioctl_rpmb_card_status_poll(card, &status, 5);
> +               if (err)
> +                       dev_err(mmc_dev(card->host),
> +                                       "%s: Card Status=0x%08X, error %d\n",
> +                                       __func__, status, err);
> +       }
> +
>  cmd_rel_host:
>         mmc_release_host(card->host);
>
> --
> 1.7.11.1
>
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Hi,
  Any specific reason why the RPMB support is implemented using the
IOCTL interface. Can this be done by the Kernel itself instead of
being initiated by a user space application ?

--
regards,
Shashidhar Hiremath