arm: cpu: Add ACPI parking protocol support
On Arm platforms that use ACPI they cannot rely on the "spin-table"
CPU bringup usually defined in the FDT. Thus implement the
'ACPI Multi-processor Startup for ARM Platforms', also referred to as
'ACPI parking protocol'.
The ACPI parking protocol works similar to the spin-table mechanism, but
the specification also covers lots of shortcomings of the spin-table
implementations.
Every CPU defined in the ACPI MADT table has it's own 4K page where the
spinloop code and the OS mailbox resides. When selected the U-Boot board
code must make sure that the secondary CPUs enter u-boot after relocation
as well, so that they can enter the spinloop code residing in the ACPI
parking protocol pages.
The OS will then write to the mailbox and generate an IPI to release the
CPUs from the spinloop code.
For now it's only implemented on ARMv8, but can easily be extended to
other platforms, like ARMv7.
TEST: Boots all CPUs on qemu-system-aarch64 -machine raspi4b
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Cc: Simon Glass <sjg@chromium.org>
Cc: Tom Rini <trini@konsulko.com>
diff --git a/arch/arm/include/asm/acpi_table.h b/arch/arm/include/asm/acpi_table.h
index c65eabe..7386f55 100644
--- a/arch/arm/include/asm/acpi_table.h
+++ b/arch/arm/include/asm/acpi_table.h
@@ -4,6 +4,7 @@
#define __ASM_ACPI_TABLE_H__
#ifndef __ACPI__
+#ifndef __ASSEMBLY__
#include <acpi/acpi_table.h>
@@ -109,7 +110,38 @@
const u32 sets, const u8 assoc, const u8 attributes,
const u16 line_size);
+/* Multi-processor Startup for ARM Platforms */
+/**
+ * struct acpi_pp_page - MP startup handshake mailbox
+ *
+ * Defines a 4096 byte memory region that is used for starting secondary CPUs on
+ * an Arm system that follows the "Multi-processor Startup for ARM Platforms" spec.
+ *
+ * @cpu_id: MPIDR as returned by the Multiprocessor Affinity Register.
+ * On 32bit Arm systems the upper bits are unused.
+ * @jumping_address: On 32bit Arm systems the address must be below 4 GiB
+ * @os_reserved: Reserved for OS use. Firmware must not access this memory.
+ * @spinning_code: Reserved for firmware use. OS must not access this memory.
+ * The spinning code will be installed by firmware and the secondary
+ * CPUs will enter it before the control is handed over to the OS.
+ */
+struct acpi_pp_page {
+ u64 cpu_id;
+ u64 jumping_address;
+ u8 os_reserved[2032];
+ u8 spinning_code[2048];
+} __packed;
+
#endif /* !__ASSEMBLY__ */
#endif /* !__ACPI__ */
+/* Multi-processor Startup for ARM Platforms defines */
+#define ACPI_PP_CPU_ID_INVALID 0xffffffff
+#define ACPI_PP_JMP_ADR_INVALID 0
+#define ACPI_PP_PAGE_SIZE 4096
+#define ACPI_PP_CPU_ID_OFFSET 0
+#define ACPI_PP_CPU_JMP_OFFSET 8
+#define ACPI_PP_CPU_CODE_OFFSET 2048
+#define ACPI_PP_VERSION 1
+
#endif /* __ASM_ACPI_TABLE_H__ */