RE: [RFC PATCH 4/4] mmc: renesas_sdhi: Add support for RZ/V2H(P) SoC

[Biju Das]

Hi Prabhakar,


> -----Original Message-----
> From: Lad, Prabhakar <prabhakar.csengg@xxxxxxxxx>
> Sent: Thursday, June 6, 2024 10:38 AM
> Subject: Re: [RFC PATCH 4/4] mmc: renesas_sdhi: Add support for RZ/V2H(P) SoC
> 
> Hi Biju,
> 
> Thank you for the review.
> 
> On Thu, Jun 6, 2024 at 10:32 AM Biju Das <biju.das.jz@xxxxxxxxxxxxxx> wrote:
> >
> > Hi Prabhakar,
> >
> > Thanks for the feedback.
> >
> > > -----Original Message-----
> > > From: Prabhakar <prabhakar.csengg@xxxxxxxxx>
> > > Sent: Wednesday, June 5, 2024 8:50 AM
> > > Subject: [RFC PATCH 4/4] mmc: renesas_sdhi: Add support for
> > > RZ/V2H(P) SoC
> > >
> > > From: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
> > >
> > > The SDHI/eMMC IPs found in the RZ/V2H(P) (a.k.a. r9a09g057) are very
> > > similar to those found in R- Car Gen3. However, they are not
> > > identical, necessitating an SoC-specific compatible string for fine-tuning driver support.
> > >
> > > Key features of the RZ/V2H(P) SDHI/eMMC IPs include:
> > > - Voltage level control via the IOVS bit.
> > > - PWEN pin support via SD_STATUS register.
> > > - Lack of HS400 support.
> > > - Fixed address mode operation.
> > >
> > > sd_iovs and sd_pwen quirks are introduced for SoCs supporting this
> > > bit to handle voltage level control and power enable via SD_STATUS register.
> > >
> > > regulator support is added to control the volatage levels of SD pins
> > > via sd_iovs bit in SD_STATUS register.
> > >
> > > Signed-off-by: Lad Prabhakar
> > > <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
> > > ---
> > >  drivers/mmc/host/renesas_sdhi.h               |  7 ++
> > >  drivers/mmc/host/renesas_sdhi_core.c          | 67 +++++++++++++++++--
> > >  drivers/mmc/host/renesas_sdhi_internal_dmac.c | 45 +++++++++++++
> > >  drivers/mmc/host/tmio_mmc.h                   |  4 ++
> > >  4 files changed, 118 insertions(+), 5 deletions(-)
> > >
> > > diff --git a/drivers/mmc/host/renesas_sdhi.h
> > > b/drivers/mmc/host/renesas_sdhi.h index
> > > 586f94d4dbfd..9ef4fdf44280 100644
> > > --- a/drivers/mmc/host/renesas_sdhi.h
> > > +++ b/drivers/mmc/host/renesas_sdhi.h
> > > @@ -11,6 +11,8 @@
> > >
> > >  #include <linux/dmaengine.h>
> > >  #include <linux/platform_device.h>
> > > +#include <linux/regmap.h>
> > > +#include <linux/regulator/driver.h>
> > >  #include "tmio_mmc.h"
> > >
> > >  struct renesas_sdhi_scc {
> > > @@ -49,6 +51,11 @@ struct renesas_sdhi_quirks {
> > >       bool manual_tap_correction;
> > >       bool old_info1_layout;
> > >       u32 hs400_bad_taps;
> > > +     bool sd_iovs;
> > > +     bool sd_pwen;
> > > +     struct regulator_desc *rdesc;
> > > +     const struct regmap_config *rdesc_regmap_config;
> > > +     unsigned int rdesc_offset;
> > >       const u8 (*hs400_calib_table)[SDHI_CALIB_TABLE_MAX];
> > >  };
> > >
> > > diff --git a/drivers/mmc/host/renesas_sdhi_core.c
> > > b/drivers/mmc/host/renesas_sdhi_core.c
> > > index 12f4faaaf4ee..2eeea9513a23 100644
> > > --- a/drivers/mmc/host/renesas_sdhi_core.c
> > > +++ b/drivers/mmc/host/renesas_sdhi_core.c
> > > @@ -248,6 +248,19 @@ static int renesas_sdhi_card_busy(struct mmc_host *mmc)
> > >                TMIO_STAT_DAT0);
> > >  }
> > >
> > > +static void renesas_sdhi_sd_status_pwen(struct tmio_mmc_host *host,
> > > +bool on) {
> > > +     u32 sd_status;
> > > +
> > > +     sd_ctrl_read32_rep(host, CTL_SD_STATUS, &sd_status, 1);
> > > +     if (on)
> > > +             sd_status |=  SD_STATUS_PWEN;
> > > +     else
> > > +             sd_status &=  ~SD_STATUS_PWEN;
> > > +
> > > +     sd_ctrl_write32(host, CTL_SD_STATUS, sd_status); }
> > > +
> >
> > May be use regulator_set_voltage() to set this??
> >
> This is the PWEN bit which is not modelled as a regulator, we cannot use regulator_set_voltage() to
> set this bit.

So, there may be a race between regulator driver and this bit??

> 
> > >  static int renesas_sdhi_start_signal_voltage_switch(struct mmc_host *mmc,
> > >                                                   struct mmc_ios
> > > *ios)  { @@ -587,6 +600,9 @@ static void renesas_sdhi_reset(struct
> > > tmio_mmc_host *host, bool preserve)
> > >                                         false, priv->rstc);
> > >                       /* At least SDHI_VER_GEN2_SDR50 needs manual release of reset */
> > >                       sd_ctrl_write16(host, CTL_RESET_SD, 0x0001);
> > > +                     if (sdhi_has_quirk(priv, sd_pwen))
> > > +                             renesas_sdhi_sd_status_pwen(host,
> > > + true);
> > > +
> > >                       priv->needs_adjust_hs400 = false;
> > >                       renesas_sdhi_set_clock(host, host->clk_cache);
> > >
> > > @@ -904,6 +920,34 @@ static void renesas_sdhi_enable_dma(struct tmio_mmc_host *host, bool
> enable)
> > >       renesas_sdhi_sdbuf_width(host, enable ? width : 16);  }
> > >
> > > +static int renesas_sdhi_internal_dmac_register_regulator(struct platform_device *pdev,
> > > +                                                      const struct renesas_sdhi_quirks
> *quirks) {
> > > +     struct tmio_mmc_host *host = platform_get_drvdata(pdev);
> > > +     struct renesas_sdhi *priv = host_to_priv(host);
> > > +     struct regulator_config rcfg = {
> > > +             .dev = &pdev->dev,
> > > +             .driver_data = priv,
> > > +     };
> > > +     struct regulator_dev *rdev;
> > > +     const char *devname;
> > > +
> > > +     devname = devm_kasprintf(&pdev->dev, GFP_KERNEL, "%s-vqmmc-regulator",
> > > +                              dev_name(&pdev->dev));
> > > +     if (!devname)
> > > +             return -ENOMEM;
> > > +
> > > +     quirks->rdesc->name = devname;
> > > +     rcfg.regmap = devm_regmap_init_mmio(&pdev->dev, host->ctl +
> > > + quirks->rdesc_offset,
> >
> > This is (CTL_SD_STATUS << 2) , so the variable can be dropped from quirks.
> >
> rdesc_offset is added to make code generic, that is in future if there is a new chip with a
> different offset which supports IOVS we can just pass the offset for it.

Currently there is no consumer for it, so it can save memory. When a future chip comes
we can bring back this variable??

Cheers,
Biju