On Fri, May 06, 2022 at 09:55:47PM +0100, Nikos Nikoleris wrote:
> In systems with ACPI support and when a DT is not provided, we can use
> the FADT to discover whether PSCI calls need to use smc or hvc
> calls. This change implements this but retains the default behavior;
> we check if a valid DT is provided, if not, we try to setup the PSCI
> conduit using ACPI.
>
> Signed-off-by: Nikos Nikoleris <nikos.nikoleris@xxxxxxx>
> ---
> arm/Makefile.common | 1 +
> lib/acpi.h | 5 +++++
> lib/arm/psci.c | 23 ++++++++++++++++++++++-
> lib/devicetree.c | 2 +-
> 4 files changed, 29 insertions(+), 2 deletions(-)
>
> diff --git a/arm/Makefile.common b/arm/Makefile.common
> index 38385e0..8e9b3bb 100644
> --- a/arm/Makefile.common
> +++ b/arm/Makefile.common
> @@ -38,6 +38,7 @@ cflatobjs += lib/alloc_page.o
> cflatobjs += lib/vmalloc.o
> cflatobjs += lib/alloc.o
> cflatobjs += lib/devicetree.o
> +cflatobjs += lib/acpi.o
> cflatobjs += lib/pci.o
> cflatobjs += lib/pci-host-generic.o
> cflatobjs += lib/pci-testdev.o
> diff --git a/lib/acpi.h b/lib/acpi.h
> index 9f27eb1..139ccba 100644
> --- a/lib/acpi.h
> +++ b/lib/acpi.h
> @@ -130,6 +130,11 @@ struct acpi_table_fadt
> u64 hypervisor_id; /* Hypervisor Vendor ID (ACPI 6.0) */
> } __attribute__ ((packed));
>
> +/* Masks for FADT ARM Boot Architecture Flags (arm_boot_flags) ACPI 5.1 */
> +
> +#define ACPI_FADT_PSCI_COMPLIANT (1) /* 00: [V5+] PSCI 0.2+ is implemented */
> +#define ACPI_FADT_PSCI_USE_HVC (1<<1) /* 01: [V5+] HVC must be used instead of SMC as the PSCI conduit */
> +
> struct facs_descriptor_rev1
> {
> u32 signature; /* ACPI Signature */
> diff --git a/lib/arm/psci.c b/lib/arm/psci.c
> index 9c031a1..0e96d19 100644
> --- a/lib/arm/psci.c
> +++ b/lib/arm/psci.c
> @@ -6,6 +6,7 @@
> *
> * This work is licensed under the terms of the GNU LGPL, version 2.
> */
> +#include <acpi.h>
> #include <devicetree.h>
> #include <asm/psci.h>
> #include <asm/setup.h>
> @@ -56,7 +57,7 @@ void psci_system_off(void)
> printf("CPU%d unable to do system off (error = %d)\n", smp_processor_id(), err);
> }
>
> -void psci_set_conduit(void)
> +static void psci_set_conduit_fdt(void)
> {
> const void *fdt = dt_fdt();
> const struct fdt_property *method;
> @@ -75,3 +76,23 @@ void psci_set_conduit(void)
> else
> assert_msg(false, "Unknown PSCI conduit: %s", method->data);
> }
> +
> +static void psci_set_conduit_acpi(void)
> +{
> + struct acpi_table_fadt *fadt = find_acpi_table_addr(FACP_SIGNATURE);
> + assert_msg(fadt, "Unable to find ACPI FADT");
> + assert_msg(fadt->arm_boot_flags & ACPI_FADT_PSCI_COMPLIANT,
> + "PSCI is not supported in this platfrom");
> + if (fadt->arm_boot_flags & ACPI_FADT_PSCI_USE_HVC)
> + psci_invoke = psci_invoke_hvc;
> + else
> + psci_invoke = psci_invoke_smc;
> +}
> +
> +void psci_set_conduit(void)
> +{
> + if (dt_available())
> + psci_set_conduit_fdt();
> + else
> + psci_set_conduit_acpi();
> +}
> diff --git a/lib/devicetree.c b/lib/devicetree.c
> index 78c1f6f..3ff9d16 100644
> --- a/lib/devicetree.c
> +++ b/lib/devicetree.c
> @@ -16,7 +16,7 @@ const void *dt_fdt(void)
>
> bool dt_available(void)
> {
> - return fdt_check_header(fdt) == 0;
> + return fdt && fdt_check_header(fdt) == 0;
> }
>
> int dt_get_nr_cells(int fdtnode, u32 *nr_address_cells, u32 *nr_size_cells)
> --
> 2.25.1
>
Reviewed-by: Andrew Jones <drjones@xxxxxxxxxx>
