Re: [PATCH v4 4/4] mtd: spi-nor: otp: implement erase for Winbond and similar flashes

[<Tudor.Ambarus@microchip.com>]

On 5/21/21 10:40 PM, Michael Walle wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> Winbond flashes with OTP support provide a command to erase the OTP
> data. This might come in handy during development.
> 
> This was tested with a Winbond W25Q32JW on a LS1028A SoC with the
> NXP FSPI controller.
> 
> Signed-off-by: Michael Walle <michael@walle.cc>
> ---
>  drivers/mtd/spi-nor/core.c    |  2 +-
>  drivers/mtd/spi-nor/core.h    |  4 ++
>  drivers/mtd/spi-nor/otp.c     | 83 +++++++++++++++++++++++++++++++++++
>  drivers/mtd/spi-nor/winbond.c |  1 +
>  4 files changed, 89 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
> index bd2c7717eb10..9551effb6a44 100644
> --- a/drivers/mtd/spi-nor/core.c
> +++ b/drivers/mtd/spi-nor/core.c
> @@ -1318,7 +1318,7 @@ static u32 spi_nor_convert_addr(struct spi_nor *nor, loff_t addr)
>  /*
>   * Initiate the erasure of a single sector
>   */
> -static int spi_nor_erase_sector(struct spi_nor *nor, u32 addr)
> +int spi_nor_erase_sector(struct spi_nor *nor, u32 addr)
>  {
>         int i;
> 
> diff --git a/drivers/mtd/spi-nor/core.h b/drivers/mtd/spi-nor/core.h
> index 28a2e0be97a3..9398a8738857 100644
> --- a/drivers/mtd/spi-nor/core.h
> +++ b/drivers/mtd/spi-nor/core.h
> @@ -207,6 +207,7 @@ struct spi_nor_otp_organization {
>   * @read:      read from the SPI NOR OTP area.
>   * @write:     write to the SPI NOR OTP area.
>   * @lock:      lock an OTP region.
> + * @erase:     erase an OTP region.
>   * @is_locked: check if an OTP region of the SPI NOR is locked.
>   */
>  struct spi_nor_otp_ops {
> @@ -214,6 +215,7 @@ struct spi_nor_otp_ops {
>         int (*write)(struct spi_nor *nor, loff_t addr, size_t len,
>                      const u8 *buf);
>         int (*lock)(struct spi_nor *nor, unsigned int region);
> +       int (*erase)(struct spi_nor *nor, loff_t addr);
>         int (*is_locked)(struct spi_nor *nor, unsigned int region);
>  };
> 
> @@ -503,10 +505,12 @@ ssize_t spi_nor_read_data(struct spi_nor *nor, loff_t from, size_t len,
>                           u8 *buf);
>  ssize_t spi_nor_write_data(struct spi_nor *nor, loff_t to, size_t len,
>                            const u8 *buf);
> +int spi_nor_erase_sector(struct spi_nor *nor, u32 addr);
> 
>  int spi_nor_otp_read_secr(struct spi_nor *nor, loff_t addr, size_t len, u8 *buf);
>  int spi_nor_otp_write_secr(struct spi_nor *nor, loff_t addr, size_t len,
>                            const u8 *buf);
> +int spi_nor_otp_erase_secr(struct spi_nor *nor, loff_t addr);
>  int spi_nor_otp_lock_sr2(struct spi_nor *nor, unsigned int region);
>  int spi_nor_otp_is_locked_sr2(struct spi_nor *nor, unsigned int region);
> 
> diff --git a/drivers/mtd/spi-nor/otp.c b/drivers/mtd/spi-nor/otp.c
> index b87f96593c13..afa348a3af70 100644
> --- a/drivers/mtd/spi-nor/otp.c
> +++ b/drivers/mtd/spi-nor/otp.c
> @@ -120,6 +120,38 @@ int spi_nor_otp_write_secr(struct spi_nor *nor, loff_t addr, size_t len,
>         return ret ?: written;
>  }
> 
> +/**
> + * spi_nor_otp_erase_secr() - erase a security register
> + * @nor:        pointer to 'struct spi_nor'
> + * @addr:       offset of the security register to be erased
> + *
> + * Erase a security register by using the SPINOR_OP_ESECR command.
> + *
> + * For more information on the term "security register", see the documentation
> + * of spi_nor_otp_read_secr().
> + *
> + * This method is used on GigaDevice and Winbond flashes.
> + *
> + * Return: 0 on success, -errno otherwise
> + */
> +int spi_nor_otp_erase_secr(struct spi_nor *nor, loff_t addr)
> +{
> +       u8 erase_opcode = nor->erase_opcode;
> +       int ret;
> +
> +       ret = spi_nor_write_enable(nor);
> +       if (ret)
> +               return ret;
> +
> +       nor->erase_opcode = SPINOR_OP_ESECR;
> +       ret = spi_nor_erase_sector(nor, addr);
> +       nor->erase_opcode = erase_opcode;
> +       if (ret)
> +               return ret;
> +
> +       return spi_nor_wait_till_ready(nor);
> +}
> +
>  static int spi_nor_otp_lock_bit_cr(unsigned int region)
>  {
>         static const int lock_bits[] = { SR2_LB1, SR2_LB2, SR2_LB3 };
> @@ -360,6 +392,56 @@ static int spi_nor_mtd_otp_write(struct mtd_info *mtd, loff_t to, size_t len,
>         return spi_nor_mtd_otp_read_write(mtd, to, len, retlen, buf, true);
>  }
> 
> +static int spi_nor_mtd_otp_erase(struct mtd_info *mtd, loff_t from, size_t len)
> +{
> +       struct spi_nor *nor = mtd_to_spi_nor(mtd);
> +       const struct spi_nor_otp_ops *ops = nor->params->otp.ops;
> +       const size_t rlen = spi_nor_otp_region_len(nor);
> +       unsigned int region;
> +       loff_t rstart;
> +       int ret;
> +
> +       /* OTP erase is optional */
> +       if (!ops->erase)
> +               return -EOPNOTSUPP;

if (!len)
	return 0;

> +
> +       if (from < 0 || (from + len) > spi_nor_otp_size(nor))
> +               return -EINVAL;
> +
> +       /* the user has to explicitly ask for whole regions */
> +       if (!IS_ALIGNED(len, rlen) || !IS_ALIGNED(from, rlen))
> +               return -EINVAL;
> +
> +       ret = spi_nor_lock_and_prep(nor);
> +       if (ret)
> +               return ret;
> +
> +       ret = spi_nor_mtd_otp_range_is_locked(nor, from, len);
> +       if (ret < 0) {
> +               goto out;
> +       } else if (ret) {
> +               ret = -EROFS;
> +               goto out;
> +       }
> +
> +       while (len) {
> +               region = spi_nor_otp_offset_to_region(nor, from);
> +               rstart = spi_nor_otp_region_start(nor, region);
> +
> +               ret = ops->erase(nor, rstart);
> +               if (ret)
> +                       goto out;
> +
> +               len -= rlen;
> +               from += rlen;
> +       }
> +
> +out:
> +       spi_nor_unlock_and_unprep(nor);
> +
> +       return ret;
> +}
> +
>  static int spi_nor_mtd_otp_lock(struct mtd_info *mtd, loff_t from, size_t len)
>  {
>         struct spi_nor *nor = mtd_to_spi_nor(mtd);
> @@ -418,4 +500,5 @@ void spi_nor_otp_init(struct spi_nor *nor)
>         mtd->_read_user_prot_reg = spi_nor_mtd_otp_read;
>         mtd->_write_user_prot_reg = spi_nor_mtd_otp_write;
>         mtd->_lock_user_prot_reg = spi_nor_mtd_otp_lock;
> +       mtd->_erase_user_prot_reg = spi_nor_mtd_otp_erase;
>  }
> diff --git a/drivers/mtd/spi-nor/winbond.c b/drivers/mtd/spi-nor/winbond.c
> index 9a81c67a60c6..96573f61caf5 100644
> --- a/drivers/mtd/spi-nor/winbond.c
> +++ b/drivers/mtd/spi-nor/winbond.c
> @@ -139,6 +139,7 @@ static int winbond_set_4byte_addr_mode(struct spi_nor *nor, bool enable)
>  static const struct spi_nor_otp_ops winbond_otp_ops = {
>         .read = spi_nor_otp_read_secr,
>         .write = spi_nor_otp_write_secr,
> +       .erase = spi_nor_otp_erase_secr,
>         .lock = spi_nor_otp_lock_sr2,
>         .is_locked = spi_nor_otp_is_locked_sr2,
>  };
> --
> 2.20.1
>