[PATCH 1/8] spacemit: k1: select boot device via config registers

[Eric Chung]

On Sat, Jun 13, 2026 at 11:51 AM 'Yao Zi' via uboot <uboot at riscstar.com> wrote:
>
> On Fri, Jun 12, 2026 at 04:18:54PM -0400, Raymond Mao wrote:
> > From: Guodong Xu <guodong at riscstar.com>
> >
> > Add logic to determine the current boot device by reading the
> > SoC's configuration registers, rather than using a hardcoded
> > default.
> >
> > Signed-off-by: Guodong Xu <guodong at riscstar.com>
> > Signed-off-by: Raymond Mao <raymond.mao at riscstar.com>
> > ---
> >  board/spacemit/k1/spl.c | 77 ++++++++++++++++++++++++++++++++++++++++-
> >  1 file changed, 76 insertions(+), 1 deletion(-)
> >
> > diff --git a/board/spacemit/k1/spl.c b/board/spacemit/k1/spl.c
> > index 0db362130e4..d5e87d79fa2 100644
> > --- a/board/spacemit/k1/spl.c
> > +++ b/board/spacemit/k1/spl.c
>
> ...
>
> > @@ -379,7 +401,60 @@ void board_init_f(ulong dummy)
> >
> >  u32 spl_boot_device(void)
> >  {
> > -     return BOOT_DEVICE_SPI;
> > +     void __iomem *boot_dev = (void __iomem *)BOOT_DEV_FLAG_REG;
> > +     void __iomem *boot_strap = (void __iomem *)BOOT_PIN_SEL_REG;
> > +     u32 mode, sel, ret = 0;
> > +
> > +     mode = readl(boot_dev);
> > +     if (mode == BOOT_MODE_NONE || mode > BOOT_MODE_SD) {
> > +             sel = readl(boot_strap);
> > +             sel >>= BOOT_STRAP_MODE_OFFSET;
> > +             sel &= BOOT_STRAP_MODE_MASK;
>
> Is FIELD_GET() helpful here?
>
Yes, we can use FIELD_GET().

> > +             switch (sel) {
> > +             case BOOT_STRAP_MODE_EMMC:
> > +                     mode = BOOT_MODE_EMMC;
> > +                     break;
> > +             case BOOT_STRAP_MODE_NAND:
> > +                     mode = BOOT_MODE_NAND;
> > +                     break;
> > +             case BOOT_STRAP_MODE_SPI:
> > +                     mode = BOOT_MODE_SPI;
> > +                     break;
> > +             case BOOT_STRAP_MODE_SD:
> > +             default:
> > +                     mode = BOOT_MODE_SD;
> > +                     break;
> > +             }
> > +     }
> > +     /* TODO:
> > +      *   The current upstream DTS file only contains the eMMC node. When
> > +      *   the SD node is added via an overlay, the eMMC device ends up as
> > +      *   MMC1 in SPL.
>
> Why not fix this with an extra alias in the overlay dt?
>

That approach doesn't really help — with the alias, mmc0 and mmc1 get
swapped, which ultimately breaks ABI consistency.

The hack on MMC1 only affects its role in SPL and doesn't impact the
ABI in the devicetree. It's just a workaround. Eventually, both the
overlay and the hack will be removed once the upstream DTS is robust
enough.


> > +      *   However, the SD device should be the first device (MMC1).
> > +      *   This sequence needs to be corrected once the SD node is merged
> > +      *   into the upstream U-Boot DTS file.
> > +      */
> > +     switch (mode) {
> > +     case BOOT_MODE_EMMC:
> > +             ret = BOOT_DEVICE_MMC1;
> > +             break;
> > +     case BOOT_MODE_NAND:
> > +             ret = BOOT_DEVICE_NAND;
> > +             break;
> > +     case BOOT_MODE_SPI:
> > +             ret = BOOT_DEVICE_SPI;
> > +             break;
> > +     case BOOT_MODE_USB:
> > +             ret = BOOT_DEVICE_USB;
> > +             break;
> > +     case BOOT_MODE_SD:
> > +             ret = BOOT_DEVICE_MMC2;
> > +             break;
> > +     default:
> > +             ret = BOOT_DEVICE_MMC1;
> > +             break;
> > +     }
> > +     return ret;
> >  }
> >
> >  void spl_board_init(void)
> > --
> > 2.25.1
> >
>
> Regards,
> Yao Zi