Add the binding to use mailbox wakeup mechanism to bringup APs. Signed-off-by: Yunhong Jiang <yunhong.jiang@xxxxxxxxxxxxxxx> --- .../devicetree/bindings/x86/wakeup.yaml | 64 +++++++++++++++++++ 1 file changed, 64 insertions(+) create mode 100644 Documentation/devicetree/bindings/x86/wakeup.yaml diff --git a/Documentation/devicetree/bindings/x86/wakeup.yaml b/Documentation/devicetree/bindings/x86/wakeup.yaml new file mode 100644 index 000000000000..cb84e2756bca --- /dev/null +++ b/Documentation/devicetree/bindings/x86/wakeup.yaml @@ -0,0 +1,64 @@ +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) +# Copyright (C) 2024 Intel Corporation +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/x86/wakeup.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml# + +title: x86 mailbox wakeup +maintainers: + - Yunhong Jiang <yunhong.jiang@xxxxxxxxxxxxxxx> + +description: | + The x86 mailbox wakeup mechanism defines a mechanism to let the bootstrap + processor (BSP) to wake up application processors (APs) through a wakeup + mailbox. + + The "wakeup-mailbox-addr" property specifies the wakeup mailbox address. The + wakeup mailbox is a 4K-aligned 4K-size memory block allocated in the reserved + memory. + + The wakeup mailbox structure is defined as follows. + + uint16_t command; + uint16_t reserved; + uint32_t apic_id; + uint64_t wakeup_vector; + uint8_t reservedForOs[2032]; + + The memory after reservedForOs field is reserved and OS should not touch it. + + To wakes up a AP, the BSP prepares the wakeup routine, fills the wakeup + routine's address into the wakeup_vector field, fill the apic_id field with + the target AP's APIC_ID, and write 1 to the command field. After receiving the + wakeup command, the target AP will jump to the wakeup routine. + + For each AP, the mailbox can be used only once for the wakeup command. After + the AP jumps to the wakeup routine, the mailbox will no longer be checked by + this AP. + + The wakeup mailbox structure and the wakeup process is the same as + the Multiprocessor Wakeup Mailbox Structure defined in ACPI spec version 6.5, + section 5.2.12.19 [1]. + + References: + + [1] https://uefi.org/specs/ACPI/6.5/05_ACPI_Software_Programming_Model.html + +select: false + +properties: + wakeup-mailbox-addr: + $ref: /schemas/types.yaml#/definitions/uint64 + description: | + The physical address of the wakeup mailbox data structure. The address + must be 4K bytes aligned 4k-size memory and it should be in the reserved + memory. + + This requires the "enable-method" property in the cpus node is set to + "acpi-wakeup-mailbox". + +required: + - wakeup-mailbox-addr + +additionalProperties: false -- 2.25.1
