[PATCH] rpi: Copy properties from firmware dtb to the loaded dtb

[Peter Robinson]

Hi Sjoerd,

> The RPI firmware adjusts several property values in the dtb it passes
> to u-boot depending on the board/SoC revision. Inherit some of these
> when u-boot loads a dtb itself. Specificaly copy:

Overall this looks great.

> * /model: The firmware provides a more specific string
> * /memreserve: The firmware defines a reserved range, better keep it
> * emmc2bus and pcie0 dma-ranges: The C0T revision of the bcm2711 Soc (as
>   present on rpi 400 and some rpi 4B boards) has different values for
>   these then the B0T revision. So these need to be adjusted to boot on
>   these boards
> * blconfig: The firmware defines the memory area where the blconfig
>   stored. Copy those over so it can be enabled.
> * /chosen/kaslr-seed: The firmware generates a kaslr seed, take advantage
>   of that.

There's also a random seed provided by the RNG_IPROC200 in U-Boot
itself, maybe if this seed provides for all generations of the rpi it
might be a better option, also usedul if this would update the seed in
U-Boot for things like the UEFI seed.

It would also likely be useful to deal with a few other pieces that
the RPi firmware provides like CMA and whether or not the serial UART
is enabled for console so it can be adjusted in U-Boot whether it
takes control of the uart. There's been a few reports over time where
U-Boot clobbers the serial port when people are trying to use it for
other things.

I'll give this a test in the next few days.

Peter

> Signed-off-by: Sjoerd Simons <sjoerd at collabora.com>
> ---
>
>  board/raspberrypi/rpi/rpi.c | 47 +++++++++++++++++++++++++++++++++++++
>  1 file changed, 47 insertions(+)
>
> diff --git a/board/raspberrypi/rpi/rpi.c b/board/raspberrypi/rpi/rpi.c
> index df52a4689f..d9467f4bda 100644
> --- a/board/raspberrypi/rpi/rpi.c
> +++ b/board/raspberrypi/rpi/rpi.c
> @@ -495,8 +495,55 @@ void *board_fdt_blob_setup(void)
>         return (void *)fw_dtb_pointer;
>  }
>
> +int copy_property(void *dst, void *src, char *path, char *property)
> +{
> +       int dst_offset, src_offset;
> +       const fdt32_t *prop;
> +       int len;
> +
> +       src_offset = fdt_path_offset(src, path);
> +       dst_offset = fdt_path_offset(dst, path);
> +
> +       if (src_offset < 0 || dst_offset < 0)
> +               return -1;
> +
> +       prop = fdt_getprop(src, src_offset, property, &len);
> +       if (!prop)
> +               return -1;
> +
> +       return fdt_setprop(dst, dst_offset, property, prop, len);
> +}
> +
> +/* Copy tweaks from the firmware dtb to the loaded dtb */
> +void  update_fdt_from_fw(void *fdt, void *fw_fdt)
> +{
> +       /* Using dtb from firmware directly; leave it alone */
> +       if (fdt == fw_fdt)
> +               return;
> +
> +       /* The firmware provides a more precie model; so copy that */
> +       copy_property(fdt, fw_fdt, "/", "model");
> +
> +       /* memory reserve as suggested by the firmware */
> +       copy_property(fdt, fw_fdt, "/", "memreserve");
> +
> +       /* Adjust dma-ranges for the SD card and PCI bus as they can depend on
> +        * the SoC revision
> +        */
> +       copy_property(fdt, fw_fdt, "emmc2bus", "dma-ranges");
> +       copy_property(fdt, fw_fdt, "pcie0", "dma-ranges");
> +
> +       /* Bootloader configuration template exposes as nvmem */
> +       if (copy_property(fdt, fw_fdt, "blconfig", "reg") == 0)
> +               copy_property(fdt, fw_fdt, "blconfig", "status");
> +
> +       /* kernel address randomisation seed as provided by the firmware */
> +       copy_property(fdt, fw_fdt, "/chosen", "kaslr-seed");
> +}
> +
>  int ft_board_setup(void *blob, struct bd_info *bd)
>  {
> +       update_fdt_from_fw(blob, (void *)fw_dtb_pointer);
>         /*
>          * For now, we simply always add the simplefb DT node. Later, we
>          * should be more intelligent, and e.g. only do this if no enabled DT
> --
> 2.33.0
>