[PATCH 1/4] board: starfive: function to read eMMC size

[E Shattow]

On Mon, Apr 15, 2024 at 4:50 AM Heinrich Schuchardt
<heinrich.schuchardt at canonical.com> wrote:
>
> The EEPROM provides information about the size of the EEPROM.

"The EEPROM provides information about the size of the eMMC."

> Provide a new function get_mmc_size_from_eeprom() to read it.
>
> Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt at canonical.com>
> ---
>  arch/riscv/include/asm/arch-jh7110/eeprom.h    |  7 +++++++
>  board/starfive/visionfive2/Kconfig             |  9 +++++++++
>  .../visionfive2/visionfive2-i2c-eeprom.c       | 18 ++++++++++++++++++
>  3 files changed, 34 insertions(+)
>
> diff --git a/arch/riscv/include/asm/arch-jh7110/eeprom.h b/arch/riscv/include/asm/arch-jh7110/eeprom.h
> index 62d184aeb57..17395d4269e 100644
> --- a/arch/riscv/include/asm/arch-jh7110/eeprom.h
> +++ b/arch/riscv/include/asm/arch-jh7110/eeprom.h
> @@ -12,6 +12,13 @@
>  u8 get_pcb_revision_from_eeprom(void);
>  u32 get_ddr_size_from_eeprom(void);
>
> +/**
> + * get_mmc_size_from_eeprom() - read MMC size form EEPROM
> + *
> + * @return: size in GiB or 0 on error.
> + */
> +u32 get_mmc_size_from_eeprom(void);
> +
>  /**
>   * get_product_id_from_eeprom - get product ID string
>   *
> diff --git a/board/starfive/visionfive2/Kconfig b/board/starfive/visionfive2/Kconfig
> index 2186a939646..d7e8a7a7d78 100644
> --- a/board/starfive/visionfive2/Kconfig
> +++ b/board/starfive/visionfive2/Kconfig
> @@ -50,4 +50,13 @@ config BOARD_SPECIFIC_OPTIONS # dummy
>         imply PHY_LIB
>         imply PHY_MSCC
>
> +config STARFIVE_NO_EMMC
> +       bool "Report eMMC size as zero"
> +       help
> +         The serial number string in the EEPROM is meant to report the
> +         size of onboard eMMC. Unfortunately some Milk-V Mars CM Lite
> +         modules without eMMC show a non-zero size here.
> +
> +         Set to 'Y' if you have a Mars CM Lite module.
> +
>  endif
> diff --git a/board/starfive/visionfive2/visionfive2-i2c-eeprom.c b/board/starfive/visionfive2/visionfive2-i2c-eeprom.c
> index ddef7d61235..cd3d8bd51a6 100644
> --- a/board/starfive/visionfive2/visionfive2-i2c-eeprom.c
> +++ b/board/starfive/visionfive2/visionfive2-i2c-eeprom.c
> @@ -548,6 +548,24 @@ u32 get_ddr_size_from_eeprom(void)
>         return hextoul(&pbuf.eeprom.atom1.data.pstr[14], NULL);
>  }
>
> +u32 get_mmc_size_from_eeprom(void)
> +{
> +       u32 size;
> +
> +       if (IS_ENABLED(CONFIG_STARFIVE_NO_EMMC))
> +               return 0;
> +
> +       if (read_eeprom())
> +               return 0;
> +
> +       size = dectoul(&pbuf.eeprom.atom1.data.pstr[19], NULL);
> +
> +       if (pbuf.eeprom.atom1.data.pstr[21] == 'T')
> +               size <<= 10;
> +
> +       return size;
> +}
> +
>  U_BOOT_LONGHELP(mac,
>         "\n"
>         "    - display EEPROM content\n"
> --
> 2.43.0
>

Fixed-position parsing on a data format of ordered variable length
hyphen-delimited fields. Notable is that some Pine64 Star64 and Milk-V
Mars CM Lite boards shipped with uninitialized or wrong EEPROM data;
further the EEPROM Write Protect can be trivially disabled and
arbitrary data written i.e. with a paperclip then `mac` command. Could
this code be generalized to split fields on hyphen character better
expressing the expected data format or is that unwanted complexity and
code size?