Commit 5e89c55e authored by Lorenzo Pieralisi's avatar Lorenzo Pieralisi Committed by Catalin Marinas
Browse files

arm64: kernel: implement ACPI parking protocol 

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@redhat.com>

[1] https://acpica.org/sites/acpica/files/MP%20Startup%20for%20ARM%20platforms.docx



Signed-off-by: default avatarLorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Tested-by: default avatarLoc Ho <lho@apm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Hanjun Guo <hanjun.guo@linaro.org>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mark Salter <msalter@redhat.com>
Cc: Al Stone <ahs3@redhat.com>
[catalin.marinas@arm.com: Added WARN_ONCE(!acpi_parking_protocol_valid() on the IPI]
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent 068a17a5

arch/arm64/Kconfig

+9 −0
Original line number Diff line number Diff line
@@ -756,6 +756,15 @@ endmenu 


menu "Boot options"



config ARM64_ACPI_PARKING_PROTOCOL

	bool "Enable support for the ARM64 ACPI parking protocol"

	depends on ACPI

	help

	  Enable support for the ARM64 ACPI parking protocol. If disabled

	  the kernel will not allow booting through the ARM64 ACPI parking

	  protocol even if the corresponding data is present in the ACPI

	  MADT table.



config CMDLINE

	string "Default kernel command string"

	default ""

arch/arm64/include/asm/acpi.h

+18 −1
Original line number Diff line number Diff line
@@ -87,9 +87,26 @@ void __init acpi_init_cpus(void); 
static inline void acpi_init_cpus(void) { }

#endif /* CONFIG_ACPI */



#ifdef CONFIG_ARM64_ACPI_PARKING_PROTOCOL

bool acpi_parking_protocol_valid(int cpu);

void __init

acpi_set_mailbox_entry(int cpu, struct acpi_madt_generic_interrupt *processor);

#else

static inline bool acpi_parking_protocol_valid(int cpu) { return false; }

static inline void

acpi_set_mailbox_entry(int cpu, struct acpi_madt_generic_interrupt *processor)

{}

#endif



static inline const char *acpi_get_enable_method(int cpu)

{

	return acpi_psci_present() ? "psci" : NULL;

	if (acpi_psci_present())

		return "psci";



	if (acpi_parking_protocol_valid(cpu))

		return "parking-protocol";



	return NULL;

}



#ifdef	CONFIG_ACPI_APEI

arch/arm64/include/asm/hardirq.h

+1 −1
Original line number Diff line number Diff line
@@ -20,7 +20,7 @@ 
#include <linux/threads.h>

#include <asm/irq.h>



#define NR_IPI	5

#define NR_IPI	6



typedef struct {

	unsigned int __softirq_pending;

arch/arm64/include/asm/smp.h

+9 −0
Original line number Diff line number Diff line
@@ -64,6 +64,15 @@ extern void secondary_entry(void); 
extern void arch_send_call_function_single_ipi(int cpu);

extern void arch_send_call_function_ipi_mask(const struct cpumask *mask);



#ifdef CONFIG_ARM64_ACPI_PARKING_PROTOCOL

extern void arch_send_wakeup_ipi_mask(const struct cpumask *mask);

#else

static inline void arch_send_wakeup_ipi_mask(const struct cpumask *mask)

{

	BUILD_BUG();

}

#endif



extern int __cpu_disable(void);



extern void __cpu_die(unsigned int cpu);

arch/arm64/kernel/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -41,6 +41,7 @@ arm64-obj-$(CONFIG_EFI) += efi.o efi-entry.stub.o 
arm64-obj-$(CONFIG_PCI)			+= pci.o

arm64-obj-$(CONFIG_ARMV8_DEPRECATED)	+= armv8_deprecated.o

arm64-obj-$(CONFIG_ACPI)		+= acpi.o

arm64-obj-$(CONFIG_ARM64_ACPI_PARKING_PROTOCOL)	+= acpi_parking_protocol.o

arm64-obj-$(CONFIG_PARAVIRT)		+= paravirt.o



obj-y					+= $(arm64-obj-y) vdso/

CRA Git | Maintained and supported by SUSTech CRA and CCSE