Re: [PATCH 8/9] mmc: mmci: sdmmc: add voltage switch functions

[Ludovic BARRE]

hi Ulf

Le 1/24/20 Ã 2:16 PM, Ulf Hansson a ÃcritÂ:
> On Fri, 10 Jan 2020 at 14:49, Ludovic Barre <ludovic.barre@xxxxxx> wrote:
> > To prepare the voltage switch procedure, the VSWITCHEN bit must be
> > set before sending the cmd11.
> > To confirm completion of voltage switch, the VSWEND flag must be
> > checked.
> >
> > Signed-off-by: Ludovic Barre <ludovic.barre@xxxxxx>
> > ---
> >   drivers/mmc/host/mmci.h             |  4 +++
> >   drivers/mmc/host/mmci_stm32_sdmmc.c | 40 ++++++++++++++++++++++++++++-
> >   2 files changed, 43 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/mmc/host/mmci.h b/drivers/mmc/host/mmci.h
> > index c04a144259a2..3634f98ad2d8 100644
> > --- a/drivers/mmc/host/mmci.h
> > +++ b/drivers/mmc/host/mmci.h
> > @@ -165,6 +165,7 @@
> >   /* Extended status bits for the STM32 variants */
> >   #define MCI_STM32_BUSYD0       BIT(20)
> >   #define MCI_STM32_BUSYD0END    BIT(21)
> > +#define MCI_STM32_VSWEND       BIT(25)
> >
> >   #define MMCICLEAR              0x038
> >   #define MCI_CMDCRCFAILCLR      (1 << 0)
> > @@ -182,6 +183,9 @@
> >   #define MCI_ST_SDIOITC         (1 << 22)
> >   #define MCI_ST_CEATAENDC       (1 << 23)
> >   #define MCI_ST_BUSYENDC                (1 << 24)
> > +/* Extended clear bits for the STM32 variants */
> > +#define MCI_STM32_VSWENDC      BIT(25)
> > +#define MCI_STM32_CKSTOPC      BIT(26)
> >
> >   #define MMCIMASK0              0x03c
> >   #define MCI_CMDCRCFAILMASK     (1 << 0)
> > diff --git a/drivers/mmc/host/mmci_stm32_sdmmc.c b/drivers/mmc/host/mmci_stm32_sdmmc.c
> > index 10059fa19f4a..9f43cf947c5f 100644
> > --- a/drivers/mmc/host/mmci_stm32_sdmmc.c
> > +++ b/drivers/mmc/host/mmci_stm32_sdmmc.c
> > @@ -263,7 +263,9 @@ static void mmci_sdmmc_set_pwrreg(struct mmci_host *host, unsigned int pwr)
> >          struct mmc_ios ios = host->mmc->ios;
> >          struct sdmmc_dlyb *dlyb = host->variant_priv;
> >
> > -       pwr = host->pwr_reg_add;
> > +       /* adds OF options and preserves voltage switch bits */
> > +       pwr = host->pwr_reg_add |
> > +               (host->pwr_reg & (MCI_STM32_VSWITCHEN | MCI_STM32_VSWITCH));
> >
> >          sdmmc_dlyb_input_ck(dlyb);
> >
> > @@ -454,6 +456,40 @@ static int sdmmc_execute_tuning(struct mmc_host *mmc, u32 opcode)
> >          return sdmmc_dlyb_phase_tuning(host, opcode);
> >   }
> >
> > +static void sdmmc_prep_vswitch(struct mmci_host *host)
> > +{
> > +       /* clear the voltage switch completion flag */
> > +       writel_relaxed(MCI_STM32_VSWENDC, host->base + MMCICLEAR);
> > +       /* enable Voltage switch procedure */
> > +       mmci_write_pwrreg(host, host->pwr_reg | MCI_STM32_VSWITCHEN);
> > +}
> > +
> > +static int sdmmc_vswitch(struct mmci_host *host, struct mmc_ios *ios)
> > +{
> > +       unsigned long flags;
> > +       u32 status;
> > +       int ret = 0;
> > +
> > +       if (ios->signal_voltage == MMC_SIGNAL_VOLTAGE_180) {
> > +               spin_lock_irqsave(&host->lock, flags);
> > +               mmci_write_pwrreg(host, host->pwr_reg | MCI_STM32_VSWITCH);
> > +               spin_unlock_irqrestore(&host->lock, flags);
> > +
> > +               /* wait voltage switch completion while 10ms */
> > +               ret = readl_relaxed_poll_timeout(host->base + MMCISTATUS,
> > +                                                status,
> > +                                                (status & MCI_STM32_VSWEND),
> > +                                                10, 10000);
> > +
> > +               writel_relaxed(MCI_STM32_VSWENDC | MCI_STM32_CKSTOPC,
> > +                              host->base + MMCICLEAR);
> > +               mmci_write_pwrreg(host, host->pwr_reg &
> > +                                 ~(MCI_STM32_VSWITCHEN | MCI_STM32_VSWITCH));
> > +       }
>
> Don't you need to manage things when resetting to
> MMC_SIGNAL_VOLTAGE_330, which for example happens during a card
> removal or at system suspend/resume?

The VSWITCH sequence is used only for 3.3V to 1.8V.
If there are: card remove | suspend/resume.
The power cycle of sdmmc must be reinitialised
and the reset is mandatory.

> > +
> > +       return ret;
> > +}
> > +
> >   static struct mmci_host_ops sdmmc_variant_ops = {
> >          .validate_data = sdmmc_idma_validate_data,
> >          .prep_data = sdmmc_idma_prep_data,
> > @@ -465,6 +501,8 @@ static struct mmci_host_ops sdmmc_variant_ops = {
> >          .set_clkreg = mmci_sdmmc_set_clkreg,
> >          .set_pwrreg = mmci_sdmmc_set_pwrreg,
> >          .busy_complete = sdmmc_busy_complete,
> > +       .prep_volt_switch = sdmmc_prep_vswitch,
> > +       .volt_switch = sdmmc_vswitch,
> >   };
> >
> >   void sdmmc_variant_init(struct mmci_host *host)
> > --
> > 2.17.1
>
> Kind regards
> Uffe