Re: [PATCH v2 3/3] mtd: rawnand: meson: read/write access for boot ROM pages

On 26.08.2024 13:42, Michael Nazzareno Trimarchi wrote:
> Hi
> 
> On Mon, Aug 26, 2024 at 11:00 AM Arseniy Krasnov
> <[email protected]> wrote:
>>
>>
>>
>> On 26.08.2024 10:16, Michael Nazzareno Trimarchi wrote:
>>> Hi
>>>
>>> On Mon, Aug 26, 2024 at 8:17 AM Arseniy Krasnov
>>> <[email protected]> wrote:
>>>>
>>>> Boot ROM on Meson needs some pages to be read/written in a special mode:
>>>> 384 byte ECC mode (so called "short" by Amlogic) and with scrambling
>>>> enabled. Such pages are located on the chip in the following way (for
>>>> example):
>>>>
>>>> [ p0 ][ p1 ][ p2 ][ p3 ][ p4 ][ p5 ][ p6 ][ p7 ] ... [ pN ]
>>>>   ^           ^           ^           ^
>>>>
>>>> pX is page number "X". "^" means "special" page used by boot ROM - e.g.
>>>> every 2nd page in the range of [0, 7]. Step (2 here) and last page in
>>>> range is read from the device tree.
>>>>
>>>> Signed-off-by: Arseniy Krasnov <[email protected]>
>>>> ---
>>>>  drivers/mtd/nand/raw/meson_nand.c | 56 +++++++++++++++++++++++++------
>>>>  1 file changed, 46 insertions(+), 10 deletions(-)
>>>>
>>>> diff --git a/drivers/mtd/nand/raw/meson_nand.c b/drivers/mtd/nand/raw/meson_nand.c
>>>> index 19f005202b..54ea035d8d 100644
>>>> --- a/drivers/mtd/nand/raw/meson_nand.c
>>>> +++ b/drivers/mtd/nand/raw/meson_nand.c
>>>> @@ -40,6 +40,7 @@
>>>>  #define NFC_CMD_RB                     BIT(20)
>>>>  #define NFC_CMD_SCRAMBLER_ENABLE       BIT(19)
>>>>  #define NFC_CMD_SCRAMBLER_DISABLE      0
>>>> +#define NFC_CMD_SHORTMODE_ENABLE       1
>>>>  #define NFC_CMD_SHORTMODE_DISABLE      0
>>>>  #define NFC_CMD_RB_INT                 BIT(14)
>>>>  #define NFC_CMD_RB_INT_NO_PIN          ((0xb << 10) | BIT(18) | BIT(16))
>>>> @@ -78,6 +79,8 @@
>>>>
>>>>  #define DMA_DIR(dir)           ((dir) ? NFC_CMD_N2M : NFC_CMD_M2N)
>>>>
>>>> +#define NFC_SHORT_MODE_ECC_SZ  384
>>>> +
>>>>  #define ECC_CHECK_RETURN_FF    -1
>>>>
>>>>  #define NAND_CE0               (0xe << 10)
>>>> @@ -141,6 +144,8 @@
>>>>  struct meson_nfc_nand_chip {
>>>>         struct list_head node;
>>>>         struct nand_chip nand;
>>>> +       u32 boot_pages;
>>>> +       u32 boot_page_step;
>>>>
>>>>         u32 bch_mode;
>>>>         u8 *data_buf;
>>>> @@ -229,33 +234,46 @@ static void meson_nfc_cmd_seed(const struct meson_nfc *nfc, u32 seed)
>>>>                nfc->reg_base + NFC_REG_CMD);
>>>>  }
>>>>
>>>> +static int meson_nfc_is_boot_page(struct nand_chip *nand, int page)
>>>> +{
>>>> +       const struct meson_nfc_nand_chip *meson_chip = to_meson_nand(nand);
>>>> +
>>>> +       return (nand->options & NAND_IS_BOOT_MEDIUM) &&
>>>> +              !(page % meson_chip->boot_page_step) &&
>>>> +              (page < meson_chip->boot_pages);
>>>> +}
>>>> +
>>>>  static void meson_nfc_cmd_access(struct nand_chip *nand, bool raw, bool dir, int page)
>>>>  {
>>>> +       const struct meson_nfc_nand_chip *meson_chip = to_meson_nand(nand);
>>>>         struct mtd_info *mtd = nand_to_mtd(nand);
>>>>         const struct meson_nfc *nfc = nand_get_controller_data(mtd_to_nand(mtd));
>>>> -       const struct meson_nfc_nand_chip *meson_chip = to_meson_nand(nand);
>>>> -       u32 bch = meson_chip->bch_mode, cmd;
>>>>         int len = mtd->writesize, pagesize, pages;
>>>>         int scrambler;
>>>> +       u32 cmd;
>>>>
>>>>         if (nand->options & NAND_NEED_SCRAMBLING)
>>>>                 scrambler = NFC_CMD_SCRAMBLER_ENABLE;
>>>>         else
>>>>                 scrambler = NFC_CMD_SCRAMBLER_DISABLE;
>>>>
>>>
>>> scrambler depends on NAND_NEED_SCRAMBLING so suppose
>>> that is not set
>>>
>>> scrambler = NAND_NEED_SCRAMBLING;
>>>
>>>> -       pagesize = nand->ecc.size;
>>>> -
>>>>         if (raw) {
>>>>                 len = mtd->writesize + mtd->oobsize;
>>>>                 cmd = len | scrambler | DMA_DIR(dir);
>>>> -               writel(cmd, nfc->reg_base + NFC_REG_CMD);
>>>> -               return;
>>>> -       }
>>>> +       } else if (meson_nfc_is_boot_page(nand, page)) {
>>>
>>> Now here you  seems that you don't care anymore about this option and check
>>> only meson_nfc_is_boot_page
>>>
>>> Is something am I missing?
>>
>> Idea is the following IIUC: such boot pages could be read in ECC mode only with enabled scrambling -
>> otherwise we get ECC error. Or we need to read it in raw mode. So:
>>
>> if (read page in raw mode) {
>>     use scrambler as provided
>> } else if (read boot page in ECC mode) {
>>     force scrambling mode + NFC_ECC_BCH8_1K + NFC_CMD_SHORTMODE_ENABLE
>> } else {
>>     //we read non-boot page in ECC mode
>>    use scrambler as provided
>> }
>>
>> Thanks
>>
>>
>>>
>>> Michael
>>>
>>>> +               pagesize = NFC_SHORT_MODE_ECC_SZ >> 3;
>>>> +               pages = mtd->writesize / 512;
>>>>
>>>> -       pages = len / nand->ecc.size;
>>>> +               scrambler = NFC_CMD_SCRAMBLER_ENABLE;
>>>> +               cmd = CMDRWGEN(DMA_DIR(dir), scrambler, NFC_ECC_BCH8_1K,
>>>> +                              NFC_CMD_SHORTMODE_ENABLE, pagesize, pages);
>>>> +       } else {
>>>> +               pagesize = nand->ecc.size >> 3;
>>>> +               pages = len / nand->ecc.size;
>>>>
>>>> -       cmd = CMDRWGEN(DMA_DIR(dir), scrambler, bch,
>>>> -                      NFC_CMD_SHORTMODE_DISABLE, pagesize, pages);
>>>> +               cmd = CMDRWGEN(DMA_DIR(dir), scrambler, meson_chip->bch_mode,
>>>> +                              NFC_CMD_SHORTMODE_DISABLE, pagesize, pages);
>>>> +       }
>>>>
>>>>         if (scrambler == NFC_CMD_SCRAMBLER_ENABLE)
>>>>                 meson_nfc_cmd_seed(nfc, page);
>>>> @@ -1132,6 +1150,24 @@ static int meson_nfc_nand_chip_init(struct udevice *dev, struct meson_nfc *nfc,
>>>>                 goto err_chip_buf_free;
>>>>         }
>>>>
>>>> +       if (nand->options & NAND_IS_BOOT_MEDIUM) {
>>>> +               ret = ofnode_read_u32(node, "amlogic,boot-pages",
>>>> +                                     &meson_chip->boot_pages);
>>>> +               if (ret) {
>>>> +                       dev_err(dev, "could not retrieve 'amlogic,boot-pages' property: %d",
>>>> +                               ret);
>>>> +                       goto err_chip_buf_free;
>>>> +               }
>>>> +
>>>> +               ret = ofnode_read_u32(node, "amlogic,boot-page-step",
>>>> +                                     &meson_chip->boot_page_step);
>>>> +               if (ret) {
>>>> +                       dev_err(dev, "could not retrieve 'amlogic,boot-page-step' property: %d",
>>>> +                               ret);
>>>> +                       goto err_chip_buf_free;
>>>> +               }
>>>> +       }
>>>> +
>>>>         ret = nand_register(0, mtd);
>>>>         if (ret) {
>>>>                 dev_err(dev, "'nand_register()' failed: %d\n", ret);
>>>> --
>>>> 2.30.1
>>>>
>>>
>>>
> 
> The first patch seems not apply clean to me on master
> 
> Reviewed-by: Michael Trimarchi <[email protected]>

Got it, I'll check

Thanks

> 
> 
>