[PATCH 15/17] arm: mach-bcm283x: Add ARMV8_MULTIENTRY support

[Simon Glass]

Hi Patrick,

On Sat, 27 Jul 2024 at 01:20, Patrick Rudolph
<patrick.rudolph at 9elements.com> wrote:
>
> When ACPI is enabled over FDT the APs cannot be brought out of reset
> by the OS using the "FDT spin-table" mechanism, as no FDT is provided
> to the OS. The APs must be released out of reset in u-boot and then
> brought up in an ACPI compliant fashion.
>
> When ARMV8_MULTIENTRY is specified the APs are released from reset
> and will enter U-Boot after it has been relocated as well.
>
> By default ARMV8_MULTIENTRY is not selected, keeping existing behaviour.
>
> TEST: All APs enter U-Boot when run on qemu-system-aarch64
>
> Signed-off-by: Patrick Rudolph <patrick.rudolph at 9elements.com>
> Cc: Matthias Brugger <mbrugger at suse.com>
> Cc: Peter Robinson <pbrobinson at gmail.com>
> Cc: Tom Rini <trini at konsulko.com>
> ---
>  arch/arm/mach-bcm283x/Kconfig |  2 ++
>  arch/arm/mach-bcm283x/init.c  | 47 +++++++++++++++++++++++++++++++++++
>  2 files changed, 49 insertions(+)
>
> diff --git a/arch/arm/mach-bcm283x/Kconfig b/arch/arm/mach-bcm283x/Kconfig
> index b3287ce8bc..de783aa8f5 100644
> --- a/arch/arm/mach-bcm283x/Kconfig
> +++ b/arch/arm/mach-bcm283x/Kconfig
> @@ -12,6 +12,7 @@ config BCM2836
>  config BCM2837
>         bool "Broadcom BCM2837 SoC support"
>         depends on ARCH_BCM283X
> +       select ARCH_EARLY_INIT_R
>
>  config BCM2837_32B
>         bool "Broadcom BCM2837 SoC 32-bit support"
> @@ -29,6 +30,7 @@ config BCM2837_64B
>  config BCM2711
>         bool "Broadcom BCM2711 SoC support"
>         depends on ARCH_BCM283X
> +       select ARCH_EARLY_INIT_R
>
>  config BCM2711_32B
>         bool "Broadcom BCM2711 SoC 32-bit support"
> diff --git a/arch/arm/mach-bcm283x/init.c b/arch/arm/mach-bcm283x/init.c
> index 80a10f2212..f6ccc76f39 100644
> --- a/arch/arm/mach-bcm283x/init.c
> +++ b/arch/arm/mach-bcm283x/init.c
> @@ -7,6 +7,7 @@
>   */
>
>  #include <acpi/acpi_table.h>
> +#include <asm-generic/sections.h>
>  #include <cpu_func.h>
>  #include <init.h>
>  #include <dm/device.h>
> @@ -201,6 +202,52 @@ int mach_cpu_init(void)
>                                                "brcm,bcm2712-pm");
>         if (offset > soc)
>                 rpi_wdog_base = fdt_get_base_address(gd->fdt_blob, offset);
> +       return 0;
> +}
> +
> +int arch_early_init_r(void)
> +{
> +       int cpus, offset;
> +       const char *prop;
> +       u64 release_addr64;
> +       uintptr_t *start_address;
> +
> +       if (CONFIG_IS_ENABLED(ARMV8_MULTIENTRY)) {
> +               /*
> +                * Release CPUs from reset after u-boot has been relocated.
> +                */
> +               cpus = fdt_path_offset(gd->fdt_blob, "/cpus");

We should not go hacking around in the devicetree. We need a way to
handle this through driver model. See cpu.h and perhaps add a new
operation if needed?

> +               if (cpus < 0)
> +                       return -ENODEV;
> +
> +               for (offset = fdt_first_subnode(gd->fdt_blob, cpus);
> +                    offset >= 0;
> +                    offset = fdt_next_subnode(gd->fdt_blob, offset)) {
> +                       prop = fdt_getprop(gd->fdt_blob, offset, "device_type", NULL);
> +                       if (!prop || strcmp(prop, "cpu"))
> +                               continue;
> +
> +                       prop = fdt_getprop(gd->fdt_blob, offset, "enable-method", NULL);
> +                       if (!prop || strcmp(prop, "spin-table"))
> +                               continue;
> +
> +                       release_addr64 = fdtdec_get_uint64(gd->fdt_blob, offset,
> +                                                          "cpu-release-addr", ~0ULL);
> +                       if (release_addr64 == ~0ULL)
> +                               continue;
> +
> +                       /* Point to U-Boot start */
> +                       start_address = (uintptr_t *)(uintptr_t)release_addr64;
> +                       *start_address = (uintptr_t)_start;
> +
> +                       if (!CONFIG_IS_ENABLED(SYS_DCACHE_OFF))
> +                               flush_dcache_range(release_addr64,
> +                                                  release_addr64 + sizeof(uintptr_t));
> +                       /* Send an event to wake up the secondary CPU. */
> +                       asm("dsb        ishst\n"
> +                           "sev");
> +               }
> +       }
>
>         return 0;
>  }
> --
> 2.45.2
>

Regards,
Simon