[U-Boot] [PATCH 12/22] mmc: Enable signal voltage to be selected from mmc core

[Simon Glass]

Hi Jen-Jacques,

On 12 May 2017 at 12:16, Jean-Jacques Hiblot <jjhiblot at ti.com> wrote:
> From: Kishon Vijay Abraham I <kishon at ti.com>
>
> Add a new function *mmc_set_signal_voltage* in mmc core
> which can be used during mmc initialization to select the
> signal voltage. Platform driver should use the set_ios
> callback function to select the signal voltage.
>
> Signed-off-by: Kishon Vijay Abraham I <kishon at ti.com>
> Signed-off-by: Jean-Jacques Hiblot <jjhiblot at ti.com>
> ---
>  drivers/mmc/mmc.c | 15 +++++++++++++++
>  include/mmc.h     |  5 +++++
>  2 files changed, 20 insertions(+)
>
> diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c
> index 2ae6f1c..10af81d 100644
> --- a/drivers/mmc/mmc.c
> +++ b/drivers/mmc/mmc.c
> @@ -29,6 +29,7 @@ static const unsigned int sd_au_size[] = {
>         SZ_4M / 512,    SZ_8M / 512,            (SZ_8M + SZ_4M) / 512,
>         SZ_16M / 512,   (SZ_16M + SZ_8M) / 512, SZ_32M / 512,   SZ_64M / 512,
>  };
> +static int mmc_set_signal_voltage(struct mmc *mmc, uint signal_voltage);
>
>  #if CONFIG_IS_ENABLED(MMC_TINY)
>  static struct mmc mmc_static;
> @@ -1247,6 +1248,12 @@ struct mode_width_tuning {
>         uint widths;
>  };
>
> +static int mmc_set_signal_voltage(struct mmc *mmc, uint signal_voltage)
> +{
> +       mmc->signal_voltage = signal_voltage;
> +       return mmc_set_ios(mmc);
> +}
> +
>  static const struct mode_width_tuning sd_modes_by_pref[] = {
>         {
>                 .mode = SD_HS,
> @@ -1935,6 +1942,14 @@ int mmc_start_init(struct mmc *mmc)
>                 return err;
>  #endif
>         mmc->ddr_mode = 0;
> +
> +       /* First try to set 3.3V. If it fails set to 1.8V */
> +       err = mmc_set_signal_voltage(mmc, MMC_SIGNAL_VOLTAGE_330);
> +       if (err != 0)
> +               err = mmc_set_signal_voltage(mmc, MMC_SIGNAL_VOLTAGE_180);
> +       if (err != 0)
> +               printf("failed to set signal voltage\n");

Return error?

> +
>         mmc_set_bus_width(mmc, 1);
>         mmc_set_clock(mmc, 1);
>
> diff --git a/include/mmc.h b/include/mmc.h
> index 9f20eb4..89cb26c 100644
> --- a/include/mmc.h
> +++ b/include/mmc.h
> @@ -266,6 +266,10 @@
>  #define ENHNCD_SUPPORT         (0x2)
>  #define PART_ENH_ATTRIB                (0x1f)
>
> +#define MMC_SIGNAL_VOLTAGE_330 1
> +#define MMC_SIGNAL_VOLTAGE_180 2
> +#define MMC_SIGNAL_VOLTAGE_120 3
> +
>  /* Maximum block size for MMC */
>  #define MMC_MAX_BLOCK_LEN      512
>
> @@ -452,6 +456,7 @@ struct mmc {
>         int high_capacity;
>         uint bus_width;
>         uint clock;
> +       uint signal_voltage;

Comment. What does this value mean? What units is it? Millivolts or
something else?

>         uint card_caps;
>         uint ocr;
>         uint dsr;
> --
> 1.9.1
>

Regards,
Simon