| .. 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_VENDOR_HYP_KVM_PTP_FUNC_ID: 0x86000001 |
| |
| This hypercall uses the SMC32/HVC32 calling convention: |
| |
| ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID |
| ============== ======== ===================================== |
| Function ID: (uint32) 0x86000001 |
| Arguments: (uint32) KVM_PTP_VIRT_COUNTER(0) |
| KVM_PTP_PHYS_COUNTER(1) |
| Return Values: (int32) NOT_SUPPORTED(-1) on error, or |
| (uint32) Upper 32 bits of wall clock time (r0) |
| (uint32) Lower 32 bits of wall clock time (r1) |
| (uint32) Upper 32 bits of counter (r2) |
| (uint32) Lower 32 bits of counter (r3) |
| Endianness: No Restrictions. |
| ============== ======== ===================================== |
