[RFC] [PATCH] [MTD] [OneNAND] Add write-while-program operation

[Kyungmin Park]

Hi Adrian,

Before comment the patch, I first wonder which mtd user can use this feature?

To work correctly, the upper layer sends more than 2 pages write size.
umm just override the write buffer in omap2. maybe assume mtdblock?

Thank you,
Kyungmin Park



On Thu, Aug 14, 2008 at 11:15 PM, Adrian Hunter
<ext-adrian.hunter at nokia.com> wrote:
>
> Signed-off-by: Adrian Hunter <ext-adrian.hunter at nokia.com>
> ---
> drivers/mtd/onenand/omap2.c        |    2 +
> drivers/mtd/onenand/onenand_base.c |  104
> ++++++++++++++++++++++++++++++++++++
> include/linux/mtd/onenand.h        |    4 ++
> 3 files changed, 110 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/mtd/onenand/omap2.c b/drivers/mtd/onenand/omap2.c
> index bf6bba5..236a68c 100644
> --- a/drivers/mtd/onenand/omap2.c
> +++ b/drivers/mtd/onenand/omap2.c
> @@ -674,6 +674,8 @@ static int __devinit omap2_onenand_probe(struct
> platform_device *pdev)
>        if ((r = onenand_scan(&c->mtd, 1)) < 0)
>                goto err_release_dma;
>
> +       c->mtd.write = onenand_write_while_prog;
> +
>        switch ((c->onenand.version_id >> 4) & 0xf) {
>        case 0:
>                c->freq = 40;
> diff --git a/drivers/mtd/onenand/onenand_base.c
> b/drivers/mtd/onenand/onenand_base.c
> index 5d7965f..ce10362 100644
> --- a/drivers/mtd/onenand/onenand_base.c
> +++ b/drivers/mtd/onenand/onenand_base.c
> @@ -1573,6 +1573,110 @@ static int onenand_write_ops_nolock(struct mtd_info
> *mtd, loff_t to,
>        return ret;
> }
>
> +/**
> + * onenand_write_while_prog - [MTD Interface] write while program
> + * @param mtd          MTD device structure
> + * @param to           offset to write to
> + * @param len          number of bytes to write
> + * @param retlen       pointer to variable to store the number of written
> bytes
> + * @param buf          the data to write
> + *
> + * Write while program.
> + */
> +int onenand_write_while_prog(struct mtd_info *mtd, loff_t to, size_t len,
> +                            size_t *retlen, const u_char *buf)
> +{
> +       struct onenand_chip *this = mtd->priv;
> +       int written = 0, column, uninitialized_var(thislen),
> uninitialized_var(lastlen);
> +       int ret = 0, first_time = 1, uninitialized_var(subpage),
> uninitialized_var(prev_subpage);
> +       loff_t prev = to;
> +
> +       onenand_get_device(mtd, FL_WRITING);
> +
> +       DEBUG(MTD_DEBUG_LEVEL3, "onenand_write_while_prog: to = 0x%08x, len
> = %i\n", (unsigned int) to, (int) len);
> +
> +       /* Initialize retlen, in case of early exit */
> +       *retlen = 0;
> +
> +       /* Do not allow writes past end of device */
> +       if (unlikely((to + len) > mtd->size)) {
> +               printk(KERN_ERR "onenand_write_while_prog: Attempt write to
> past end of device\n");
> +               onenand_release_device(mtd);
> +               return -EINVAL;
> +       }
> +
> +       /* Reject writes, which are not page aligned */
> +        if (unlikely(NOTALIGNED(to)) || unlikely(NOTALIGNED(len))) {
> +                printk(KERN_ERR "onenand_write_while_prog: Attempt to write
> not page aligned data\n");
> +               onenand_release_device(mtd);
> +                return -EINVAL;
> +        }
> +
> +       if (!len) {
> +               onenand_release_device(mtd);
> +               return 0;
> +       }
> +
> +       column = to & (mtd->writesize - 1);
> +
> +       /* Loop until all data is written */
> +       while (1) {
> +               if (written < len) {
> +                       u_char *wbuf = (u_char *)buf;
> +
> +                       thislen = min_t(int, mtd->writesize - column, len -
> written);
> +
> +                       cond_resched();
> +
> +                       this->command(mtd, ONENAND_CMD_BUFFERRAM, to,
> thislen);
> +
> +                       subpage = thislen < mtd->writesize;
> +                       if (subpage) {
> +                               memset(this->page_buf, 0xff,
> mtd->writesize);
> +                               memcpy(this->page_buf + column, buf,
> thislen);
> +                               wbuf = this->page_buf;
> +                       }
> +
> +                       this->write_bufferram(mtd, ONENAND_DATARAM, wbuf, 0,
> mtd->writesize);
> +                       this->write_bufferram(mtd, ONENAND_SPARERAM,
> ffchars, 0, mtd->oobsize);
> +               } else
> +                       ONENAND_SET_NEXT_BUFFERRAM(this);
> +
> +               if (!first_time) {
> +                       ONENAND_SET_PREV_BUFFERRAM(this);
> +                       ret = this->wait(mtd, FL_WRITING);
> +                       onenand_update_bufferram(mtd, prev, !ret &&
> !prev_subpage);
> +                       if (ret) {
> +                               written -= lastlen;
> +                               printk(KERN_ERR "onenand_write_while_prog:
> write failed %d\n", ret);
> +                               break;
> +                       }
> +                       if (written == len) {
> +                               ret = onenand_verify(mtd, buf - len, to -
> len, len);
> +                               if (ret)
> +                                       printk(KERN_ERR
> "onenand_write_while_prog: verify failed %d\n", ret);
> +                               break;
> +                       }
> +                       ONENAND_SET_NEXT_BUFFERRAM(this);
> +               }
> +
> +               this->command(mtd, ONENAND_CMD_PROG, to, mtd->writesize);
> +
> +               written += thislen;
> +               column = 0;
> +               prev_subpage = subpage;
> +               prev = to;
> +               to += thislen;
> +               buf += thislen;
> +               lastlen = thislen;
> +               first_time = 0;
> +       }
> +
> +       *retlen = written;
> +
> +       onenand_release_device(mtd);
> +       return ret;
> +}
>
> /**
>  * onenand_write_oob_nolock - [Internal] OneNAND write out-of-band
> diff --git a/include/linux/mtd/onenand.h b/include/linux/mtd/onenand.h
> index 9aa2a91..1223430 100644
> --- a/include/linux/mtd/onenand.h
> +++ b/include/linux/mtd/onenand.h
> @@ -24,6 +24,10 @@ extern int onenand_scan(struct mtd_info *mtd, int
> max_chips);
> /* Free resources held by the OneNAND device */
> extern void onenand_release(struct mtd_info *mtd);
>
> +/* Alternative write algorithm : write-while program */
> +int onenand_write_while_prog(struct mtd_info *mtd, loff_t to, size_t len,
> +                            size_t *retlen, const u_char *buf);
> +
> /*
>  * onenand_state_t - chip states
>  * Enumeration for OneNAND flash chip state
> --
> 1.5.4.3
>