[PATCH 1/2] rpi: Copy properties from firmware dtb to the loaded dtb

[Peter Robinson]

On Wed, Aug 10, 2022 at 1:58 PM Antoine Mazeas <antoine at karthanis.net> wrote:
>
> 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:
>
> * /model: The firmware provides a more specific string
> * /memreserve: The firmware defines a reserved range, better keep it

Is this the CMA range or a different one? If so this makes sense.

> * 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.

U-Boot has a rpi4 iproc_rng200 driver for this and provides it via the
UEFI random seed as well, if you're booting using UEFI that takes
precedence so providing this might not be useful but also it doesn't
matter much.

> Signed-off-by: Sjoerd Simons <sjoerd at collabora.com>

Reviewed-by: Peter Robinson <pbrobinson at gmail.com>
Tested-by: Peter Robinson <pbrobinson at gmail.com>

Tested on RPi400 and it solves the issues with the kernel DT I've seen
plus some RPi4s although no the rev 1.3+ devices that also have the
newer SoC rev that's the same in the rpi400

> ---
>  board/raspberrypi/rpi/rpi.c | 48 +++++++++++++++++++++++++++++++++++++
>  1 file changed, 48 insertions(+)
>
> diff --git a/board/raspberrypi/rpi/rpi.c b/board/raspberrypi/rpi/rpi.c
> index 17b8108cc8..28b6f52506 100644
> --- a/board/raspberrypi/rpi/rpi.c
> +++ b/board/raspberrypi/rpi/rpi.c
> @@ -504,10 +504,58 @@ void *board_fdt_blob_setup(int *err)
>         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)
>  {
>         int node;
>
> +       update_fdt_from_fw(blob, (void *)fw_dtb_pointer);
> +
>         node = fdt_node_offset_by_compatible(blob, -1, "simple-framebuffer");
>         if (node < 0)
>                 fdt_simplefb_add_node(blob);
> --
> 2.37.1
>