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- .. SPDX-License-Identifier: GPL-2.0
- PTP_KVM support for arm/arm64
- =============================
- PTP_KVM is used for high precision time sync between host and guests.
- It relies on transferring the wall clock and counter value from the
- host to the guest using a KVM-specific hypercall.
- ``ARM_SMCCC_KVM_FUNC_PTP``
- ----------------------------------------
- Retrieve current time information for the specific counter. There are no
- endianness restrictions.
- +---------------------+-------------------------------------------------------+
- | Presence: | Optional |
- +---------------------+-------------------------------------------------------+
- | Calling convention: | HVC32 |
- +---------------------+----------+--------------------------------------------+
- | Function ID: | (uint32) | 0x86000001 |
- +---------------------+----------+----+---------------------------------------+
- | Arguments: | (uint32) | R1 | ``KVM_PTP_VIRT_COUNTER (0)`` |
- | | | +---------------------------------------+
- | | | | ``KVM_PTP_PHYS_COUNTER (1)`` |
- +---------------------+----------+----+---------------------------------------+
- | Return Values: | (int32) | R0 | ``NOT_SUPPORTED (-1)`` on error, else |
- | | | | upper 32 bits of wall clock time |
- | +----------+----+---------------------------------------+
- | | (uint32) | R1 | Lower 32 bits of wall clock time |
- | +----------+----+---------------------------------------+
- | | (uint32) | R2 | Upper 32 bits of counter |
- | +----------+----+---------------------------------------+
- | | (uint32) | R3 | Lower 32 bits of counter |
- +---------------------+----------+----+---------------------------------------+
|
