[PATCH v3] ARM64: kernel: implement ACPI parking protocol

[Catalin Marinas]

On Tue, Jan 26, 2016 at 11:10:38AM +0000, Lorenzo Pieralisi wrote:
> The SBBR and ACPI specifications allow ACPI based systems that do not
> implement PSCI (eg systems with no EL3) to boot through the ACPI parking
> protocol specification[1].
> 
> This patch implements the ACPI parking protocol CPU operations, and adds
> code that eases parsing the parking protocol data structures to the
> ARM64 SMP initializion carried out at the same time as cpus enumeration.
> 
> To wake-up the CPUs from the parked state, this patch implements a
> wakeup IPI for ARM64 (ie arch_send_wakeup_ipi_mask()) that mirrors the
> ARM one, so that a specific IPI is sent for wake-up purpose in order
> to distinguish it from other IPI sources.
> 
> Given the current ACPI MADT parsing API, the patch implements a glue
> layer that helps passing MADT GICC data structure from SMP initialization
> code to the parking protocol implementation somewhat overriding the CPU
> operations interfaces. This to avoid creating a completely trasparent
> DT/ACPI CPU operations layer that would require creating opaque
> structure handling for CPUs data (DT represents CPU through DT nodes, ACPI
> through static MADT table entries), which seems overkill given that ACPI
> on ARM64 mandates only two booting protocols (PSCI and parking protocol),
> so there is no need for further protocol additions.
> 
> Based on the original work by Mark Salter <msalter at redhat.com>
> 
> [1] https://acpica.org/sites/acpica/files/MP%20Startup%20for%20ARM%20platforms.docx
> 
> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi at arm.com>
> Cc: Will Deacon <will.deacon at arm.com>
> Cc: Hanjun Guo <hanjun.guo at linaro.org>
> Cc: Loc Ho <lho at apm.com>
> Cc: Sudeep Holla <sudeep.holla at arm.com>
> Cc: Catalin Marinas <catalin.marinas at arm.com>
> Cc: Mark Rutland <mark.rutland at arm.com>
> Cc: Mark Salter <msalter at redhat.com>
> Cc: Al Stone <ahs3 at redhat.com>

Applied, with a minor addition just to warn people from not using it in
other configurations (#ifdef still needed otherwise the
acpi_parking_protocol_valid symbol is not available; but I prefer uglier
code than people starting to use this IPI in their firmware):

--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -767,6 +767,12 @@ void handle_IPI(int ipinr, struct pt_regs *regs)
                break;
 #endif
+
+#ifdef CONFIG_ARM64_ACPI_PARKING_PROTOCOL
        case IPI_WAKEUP:
+               WARN_ONCE(!acpi_parking_protocol_valid(cpu),
+                         "CPU%u: Wake-up IPI outside the ACPI parking protocol\n",
+                         cpu);
                break;
+#endif
 
        default:

Thanks.

-- 
Catalin