Re: [PATCH v2 3/4] mtd: spi-nor: implement OTP support for Macronix and similar flashes

[Heiko Thiery <heiko.thiery@gmail.com>]

Hi Michael,

Am Sa., 12. Sept. 2020 um 00:26 Uhr schrieb Michael Walle <michael@walle.cc>:
>
> Use the new OTP ops to implement OTP access on Macronix flashes. The
> Macronix flashes provides one OTP area which is either programmed with
> an electrical serial number and locked by the factory or is empty and can
> be locked by the user. To keep things simple and because most devices
> will have unprogrammed OTP areas, we treat both options as user regions.
> If there will actually be an ESN preprogrammed, it will appear as a
> locked user region.
>
> This was tested on a Macronix MX25L6405D as well as on a Adesto
> AT25SL321.
>
> Signed-off-by: Michael Walle <michael@walle.cc>

Reviewed-by: Heiko Thiery <heiko.thiery@gmail.com>

> ---
>  drivers/mtd/spi-nor/atmel.c    |  13 ++-
>  drivers/mtd/spi-nor/core.c     | 170 +++++++++++++++++++++++++++++++++
>  drivers/mtd/spi-nor/core.h     |   9 ++
>  drivers/mtd/spi-nor/macronix.c |  13 ++-
>  include/linux/mtd/spi-nor.h    |   6 ++
>  5 files changed, 209 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/mtd/spi-nor/atmel.c b/drivers/mtd/spi-nor/atmel.c
> index 3f5f21a473a6..1688c9989c6b 100644
> --- a/drivers/mtd/spi-nor/atmel.c
> +++ b/drivers/mtd/spi-nor/atmel.c
> @@ -19,7 +19,8 @@ static const struct flash_info atmel_parts[] = {
>         { "at25df641",  INFO(0x1f4800, 0, 64 * 1024, 128, SECT_4K) },
>
>         { "at25sl321",  INFO(0x1f4216, 0, 64 * 1024, 64,
> -                            SECT_4K | SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ) },
> +                            SECT_4K | SPI_NOR_DUAL_READ | SPI_NOR_QUAD_READ)
> +                            OTP_INFO1(512, 0) },
>
>         { "at26f004",   INFO(0x1f0400, 0, 64 * 1024,  8, SECT_4K) },
>         { "at26df081a", INFO(0x1f4501, 0, 64 * 1024, 16, SECT_4K) },
> @@ -29,9 +30,19 @@ static const struct flash_info atmel_parts[] = {
>         { "at45db081d", INFO(0x1f2500, 0, 64 * 1024, 16, SECT_4K) },
>  };
>
> +static const struct spi_nor_otp_ops atmel_otp_ops = {
> +       .read = spi_nor_otp_read_otp_mode,
> +       .write = spi_nor_otp_write_otp_mode,
> +       .lock = spi_nor_otp_lock_scur,
> +       .is_locked = spi_nor_otp_is_locked_scur,
> +};
> +
>  static void atmel_default_init(struct spi_nor *nor)
>  {
>         nor->flags |= SNOR_F_HAS_LOCK;
> +
> +       if (nor->params->otp_info.n_otps)
> +               nor->params->otp_ops = &atmel_otp_ops;
>  }
>
>  static const struct spi_nor_fixups atmel_fixups = {
> diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
> index 4244f98e4948..348db19958e9 100644
> --- a/drivers/mtd/spi-nor/core.c
> +++ b/drivers/mtd/spi-nor/core.c
> @@ -2828,6 +2828,176 @@ static int spi_nor_unlock_all(struct spi_nor *nor)
>         return 0;
>  }
>
> +/**
> + * spi_nor_set_secured_otp_mode() - Set secured OTP mode
> + * @nor:       pointer to 'struct spi_nor'.
> + * @enable:    true to enter the secured OTP mode, false to exit the secured
> + *             OTP mode.
> + *
> + * Enter and exit OTP mode by using the command SPINOR_OP_ENSO (B1h) and
> + * SPINOR_EP_EXSO (C1h) command.
> + *
> + * Return: 0 on success, -errno otherwise.
> + */
> +static int spi_nor_set_secured_otp_mode(struct spi_nor *nor, bool enable)
> +{
> +       u8 cmd = enable ? SPINOR_OP_ENSO : SPINOR_OP_EXSO;
> +       int ret;
> +
> +       ret = spi_nor_simple_cmd(nor, cmd);
> +       if (ret)
> +               dev_dbg(nor->dev, "error %d setting secured OTP mode\n", ret);
> +
> +       return ret;
> +}
> +
> +/**
> + * spi_nor_read_scur() - Read the Security Register using the SPINOR_OP_RDSCUR (2Bh) command.
> + * @nor:       pointer to 'struct spi_nor'
> + * @scur:      pointer to a DMA-able buffer where the value of the
> + *             Security Register will be written.
> + *
> + * Return: 0 on success, -errno otherwise.
> + */
> +static int spi_nor_read_scur(struct spi_nor *nor, u8 *scur)
> +{
> +       int ret;
> +
> +       ret = spi_nor_simple_cmd_din(nor, SPINOR_OP_RDSCUR, scur, 1);
> +       if (ret)
> +               dev_dbg(nor->dev, "error %d reading SCUR\n", ret);
> +
> +       return ret;
> +}
> +
> +/**
> + * spi_nor_write_scur() - Write the Security Register using the SPINOR_OP_WRSCUR (2Fh) command.
> + * @nor:       pointer to 'struct spi_nor'
> + *
> + * This register contains only one OTP bit. The command doesn't take any
> + * arguments. In fact it _must not_ take any arugments. Otherwise the command
> + * is ignored.
> + *
> + * Return: 0 on success, -errno otherwise.
> + */
> +static int spi_nor_write_scur(struct spi_nor *nor)
> +{
> +       int ret;
> +
> +       ret = spi_nor_simple_cmd(nor, SPINOR_OP_WRSCUR);
> +       if (ret)
> +               dev_dbg(nor->dev, "error %d writing SCUR\n", ret);
> +
> +       return ret;
> +}
> +
> +/**
> + * spi_nor_otp_read_otp_mode() - read OTP data
> + * @nor:       pointer to 'struct spi_nor'
> + * @from:       offset to read from
> + * @len:        number of bytes to read
> + * @buf:        pointer to dst buffer
> + *
> + * Read OTP data by using the ENSO and EXSO commands. This method is used on
> + * Adesto, Atmel, Macronix and Micron SPI flashes.
> + *
> + * Return: number of bytes read successfully, -errno otherwise
> + */
> +int spi_nor_otp_read_otp_mode(struct spi_nor *nor, loff_t from, uint64_t len, u8 *buf)
> +{
> +       int ret;
> +
> +       ret = spi_nor_set_secured_otp_mode(nor, true);
> +       if (ret)
> +               return ret;
> +
> +       ret = spi_nor_read_data(nor, from, len, buf);
> +
> +       spi_nor_set_secured_otp_mode(nor, false);
> +
> +       return ret;
> +}
> +
> +/**
> + * spi_nor_otp_write_otp_mode() - write OTP data
> + * @nor:        pointer to 'struct spi_nor'
> + * @to:         offset to write to
> + * @len:        number of bytes to write
> + * @buf:        pointer to src buffer
> + *
> + * Write OTP data by using the ENSO and EXSO commands. This method is used on
> + * Adesto, Atmel, Macronix and Micron SPI flashes.
> + *
> + * Return: number of bytes written successfully, -errno otherwise
> + */
> +int spi_nor_otp_write_otp_mode(struct spi_nor *nor, loff_t to, uint64_t len, u8 *buf)
> +{
> +       int ret;
> +
> +       ret = spi_nor_set_secured_otp_mode(nor, true);
> +       if (ret)
> +               return ret;
> +
> +       ret = spi_nor_write_enable(nor);
> +       if (ret)
> +               goto out;
> +
> +       ret = spi_nor_write_data(nor, to, len, buf);
> +       if (ret < 0)
> +               goto out;
> +
> +       ret = spi_nor_wait_till_ready(nor);
> +
> +out:
> +       spi_nor_set_secured_otp_mode(nor, false);
> +
> +       return ret;
> +}
> +
> +/**
> + * spi_nor_otp_lock_scur() - lock the OTP region
> + * @nor:        pointer to 'struct spi_nor'
> + * @region:     OTP region
> + *
> + * Lock the OTP region by writing the security register. This method is used on
> + * Adesto, Atmel, Macronix and Micron SPI flashes.
> + *
> + * Return: 0 on success, -errno otherwise.
> + */
> +int spi_nor_otp_lock_scur(struct spi_nor *nor, unsigned int region)
> +{
> +       if (region != 0)
> +               return -EINVAL;
> +
> +       return spi_nor_write_scur(nor);
> +}
> +
> +/**
> + * spi_nor_otp_is_locked_otp_mode() - get the OTP region lock status
> + * @nor:        pointer to 'struct spi_nor'
> + * @region:     OTP region
> + *
> + * Retrieve the OTP region lock bit by reading the security register. This
> + * method is used on Adesto, Atmel, Macronix and Micron SPI flashes.
> + *
> + * Return: 0 on success, -errno otherwise.
> + */
> +int spi_nor_otp_is_locked_scur(struct spi_nor *nor, unsigned int region)
> +{
> +       u8 *scur = nor->bouncebuf;
> +       int ret;
> +
> +       if (region != 0)
> +               return -EINVAL;
> +
> +       ret = spi_nor_read_scur(nor, scur);
> +       if (ret)
> +               return ret;
> +
> +       return *scur & SCUR_LDSO;
> +}
> +
> +
>  static int spi_nor_init(struct spi_nor *nor)
>  {
>         int err;
> diff --git a/drivers/mtd/spi-nor/core.h b/drivers/mtd/spi-nor/core.h
> index 516c5973bf88..7ec4add17b72 100644
> --- a/drivers/mtd/spi-nor/core.h
> +++ b/drivers/mtd/spi-nor/core.h
> @@ -414,6 +414,10 @@ struct flash_info {
>                 .otp_start_addr = (_otp_start_addr),                    \
>                 .otp_addr_offset = (_otp_addr_offset),
>
> +#define OTP_INFO1(_otp_size, _otp_start_addr)                          \
> +               OTP_INFO(_otp_size, 1, _otp_start_addr, 0)
> +
> +
>  /**
>   * struct spi_nor_manufacturer - SPI NOR manufacturer object
>   * @name: manufacturer name
> @@ -464,6 +468,11 @@ ssize_t spi_nor_read_data(struct spi_nor *nor, loff_t from, size_t len,
>  ssize_t spi_nor_write_data(struct spi_nor *nor, loff_t to, size_t len,
>                            const u8 *buf);
>
> +int spi_nor_otp_read_otp_mode(struct spi_nor *nor, loff_t from, uint64_t len, u8 *buf);
> +int spi_nor_otp_write_otp_mode(struct spi_nor *nor, loff_t to, uint64_t len, u8 *buf);
> +int spi_nor_otp_lock_scur(struct spi_nor *nor, unsigned int region);
> +int spi_nor_otp_is_locked_scur(struct spi_nor *nor, unsigned int region);
> +
>  int spi_nor_hwcaps_read2cmd(u32 hwcaps);
>  u8 spi_nor_convert_3to4_read(u8 opcode);
>  void spi_nor_set_pp_settings(struct spi_nor_pp_command *pp, u8 opcode,
> diff --git a/drivers/mtd/spi-nor/macronix.c b/drivers/mtd/spi-nor/macronix.c
> index f97f3d127575..31198527f963 100644
> --- a/drivers/mtd/spi-nor/macronix.c
> +++ b/drivers/mtd/spi-nor/macronix.c
> @@ -42,7 +42,8 @@ static const struct flash_info macronix_parts[] = {
>         { "mx25l1606e",  INFO(0xc22015, 0, 64 * 1024,  32, SECT_4K) },
>         { "mx25l3205d",  INFO(0xc22016, 0, 64 * 1024,  64, SECT_4K) },
>         { "mx25l3255e",  INFO(0xc29e16, 0, 64 * 1024,  64, SECT_4K) },
> -       { "mx25l6405d",  INFO(0xc22017, 0, 64 * 1024, 128, SECT_4K) },
> +       { "mx25l6405d",  INFO(0xc22017, 0, 64 * 1024, 128, SECT_4K)
> +                        OTP_INFO1(64, 0) },
>         { "mx25u2033e",  INFO(0xc22532, 0, 64 * 1024,   4, SECT_4K) },
>         { "mx25u3235f",  INFO(0xc22536, 0, 64 * 1024,  64,
>                               SECT_4K | SPI_NOR_DUAL_READ |
> @@ -92,10 +93,20 @@ static const struct flash_info macronix_parts[] = {
>                               SPI_NOR_QUAD_READ | SPI_NOR_4B_OPCODES) },
>  };
>
> +static const struct spi_nor_otp_ops macronix_otp_ops = {
> +       .read = spi_nor_otp_read_otp_mode,
> +       .write = spi_nor_otp_write_otp_mode,
> +       .lock = spi_nor_otp_lock_scur,
> +       .is_locked = spi_nor_otp_is_locked_scur,
> +};
> +
>  static void macronix_default_init(struct spi_nor *nor)
>  {
>         nor->params->quad_enable = spi_nor_sr1_bit6_quad_enable;
>         nor->params->set_4byte_addr_mode = spi_nor_set_4byte_addr_mode;
> +
> +       if (nor->params->otp_info.n_otps)
> +               nor->params->otp_ops = &macronix_otp_ops;
>  }
>
>  static const struct spi_nor_fixups macronix_fixups = {
> diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
> index 081dbd386944..04195d3e43b8 100644
> --- a/include/linux/mtd/spi-nor.h
> +++ b/include/linux/mtd/spi-nor.h
> @@ -95,6 +95,12 @@
>  /* Used for Macronix and Winbond flashes. */
>  #define SPINOR_OP_EN4B         0xb7    /* Enter 4-byte mode */
>  #define SPINOR_OP_EX4B         0xe9    /* Exit 4-byte mode */
> +#define SPINOR_OP_ENSO         0xb1    /* Enter secured OTP mode */
> +#define SPINOR_OP_EXSO         0xc1    /* Exit secured OTP mode */
> +#define SPINOR_OP_RDSCUR       0x2b    /* Read security register */
> +#define SPINOR_OP_WRSCUR       0x2f    /* Write security register */
> +#define SCUR_SO                        BIT(0)  /* OTP factory secured */
> +#define SCUR_LDSO              BIT(1)  /* OTP user lock-down */
>
>  /* Used for Spansion flashes only. */
>  #define SPINOR_OP_BRWR         0x17    /* Bank register write */
>

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