[PATCH v3 13/30] acpi: acpi_table: Support ACPI 2.0 platforms

[Peter Robinson]

> On platforms that do not have usable DRAM below 4GiB, like QEMU sbsa,
> the RSDT cannot be used. Allow both RSDT and XSDT to be null and only
> fill those tables that are present in acpi_add_table().

I'm not sure what ACPI 2.0 from the subject has to do with the above,
eg ACPI only started supporting aarch64 with ACPI 5.1

> Fixes a crash on QEMU sbsa.
>
> Signed-off-by: Patrick Rudolph <patrick.rudolph at 9elements.com>
> Cc: Simon Glass <sjg at chromium.org>
> Cc: Tom Rini <trini at konsulko.com>
> ---
>  lib/acpi/acpi_table.c | 95 ++++++++++++++++++++++++++-----------------
>  1 file changed, 57 insertions(+), 38 deletions(-)
>
> diff --git a/lib/acpi/acpi_table.c b/lib/acpi/acpi_table.c
> index 4f5cfe522c..8aab41212a 100644
> --- a/lib/acpi/acpi_table.c
> +++ b/lib/acpi/acpi_table.c
> @@ -157,51 +157,70 @@ int acpi_add_table(struct acpi_ctx *ctx, void *table)
>         struct acpi_rsdt *rsdt;
>         struct acpi_xsdt *xsdt;
>
> -       /* The RSDT is mandatory while the XSDT is not */
> -       rsdt = ctx->rsdt;
> -
> -       /* This should always be MAX_ACPI_TABLES */
> -       entries_num = ARRAY_SIZE(rsdt->entry);
> -
> -       for (i = 0; i < entries_num; i++) {
> -               if (rsdt->entry[i] == 0)
> -                       break;
> -       }
> -
> -       if (i >= entries_num) {
> -               log_err("ACPI: Error: too many tables\n");
> -               return -E2BIG;
> -       }
> +       /* On legacy x86 platforms the RSDT is mandatory while the XSDT is not.
> +        * On other platforms there might be no memory below 4GiB, thus RSDT is NULL.
> +        */
> +       if (ctx->rsdt) {
> +               rsdt = ctx->rsdt;
>
> -       /* Add table to the RSDT */
> -       rsdt->entry[i] = nomap_to_sysmem(table);
> +               /* This should always be MAX_ACPI_TABLES */
> +               entries_num = ARRAY_SIZE(rsdt->entry);
>
> -       /* Fix RSDT length or the kernel will assume invalid entries */
> -       rsdt->header.length = sizeof(struct acpi_table_header) +
> -                               (sizeof(u32) * (i + 1));
> +               for (i = 0; i < entries_num; i++) {
> +                       if (rsdt->entry[i] == 0)
> +                               break;
> +               }
>
> -       /* Re-calculate checksum */
> -       rsdt->header.checksum = 0;
> -       rsdt->header.checksum = table_compute_checksum((u8 *)rsdt,
> -                                                      rsdt->header.length);
> +               if (i >= entries_num) {
> +                       log_err("ACPI: Error: too many tables\n");
> +                       return -E2BIG;
> +               }
>
> -       /*
> -        * And now the same thing for the XSDT. We use the same index as for
> -        * now we want the XSDT and RSDT to always be in sync in U-Boot
> -        */
> -       xsdt = ctx->xsdt;
> +               /* Add table to the RSDT */
> +               rsdt->entry[i] = nomap_to_sysmem(table);
>
> -       /* Add table to the XSDT */
> -       xsdt->entry[i] = nomap_to_sysmem(table);
> +               /* Fix RSDT length or the kernel will assume invalid entries */
> +               rsdt->header.length = sizeof(struct acpi_table_header) +
> +                                       (sizeof(u32) * (i + 1));
>
> -       /* Fix XSDT length */
> -       xsdt->header.length = sizeof(struct acpi_table_header) +
> -                               (sizeof(u64) * (i + 1));
> +               /* Re-calculate checksum */
> +               rsdt->header.checksum = 0;
> +               rsdt->header.checksum = table_compute_checksum((u8 *)rsdt,
> +                                                              rsdt->header.length);
> +       }
>
> -       /* Re-calculate checksum */
> -       xsdt->header.checksum = 0;
> -       xsdt->header.checksum = table_compute_checksum((u8 *)xsdt,
> -                                                      xsdt->header.length);
> +       if (ctx->xsdt) {
> +               /*
> +                * And now the same thing for the XSDT. We use the same index as for
> +                * now we want the XSDT and RSDT to always be in sync in U-Boot
> +                */
> +               xsdt = ctx->xsdt;
> +
> +               /* This should always be MAX_ACPI_TABLES */
> +               entries_num = ARRAY_SIZE(xsdt->entry);
> +
> +               for (i = 0; i < entries_num; i++) {
> +                       if (xsdt->entry[i] == 0)
> +                               break;
> +               }
> +
> +               if (i >= entries_num) {
> +                       log_err("ACPI: Error: too many tables\n");
> +                       return -E2BIG;
> +               }
> +
> +               /* Add table to the XSDT */
> +               xsdt->entry[i] = nomap_to_sysmem(table);
> +
> +               /* Fix XSDT length */
> +               xsdt->header.length = sizeof(struct acpi_table_header) +
> +                                       (sizeof(u64) * (i + 1));
> +
> +               /* Re-calculate checksum */
> +               xsdt->header.checksum = 0;
> +               xsdt->header.checksum = table_compute_checksum((u8 *)xsdt,
> +                                                              xsdt->header.length);
> +       }
>
>         return 0;
>  }
> --
> 2.46.0
>