forked from luck/tmp_suning_uos_patched
7d10001e20
Add a PTP clock driver called ptp_vmw, for guests running on VMware ESXi hypervisor. The driver attaches to a VMware virtual device called "precision clock" that provides a mechanism for querying host system time. Similar to existing virtual PTP clock drivers (e.g. ptp_kvm), ptp_vmw utilizes the kernel's PTP hardware clock API to implement a clock device that can be used as a reference in Chrony for synchronizing guest time with host. The driver is only applicable to x86 guests running in VMware virtual machines with precision clock virtual device present. It uses a VMware specific hypercall mechanism to read time from the device. Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com> Signed-off-by: Vivek Thampi <vithampi@vmware.com> Signed-off-by: David S. Miller <davem@davemloft.net>
145 lines
3.1 KiB
C
145 lines
3.1 KiB
C
// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
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/*
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* Copyright (C) 2020 VMware, Inc., Palo Alto, CA., USA
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*
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* PTP clock driver for VMware precision clock virtual device.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/acpi.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/ptp_clock_kernel.h>
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#include <asm/hypervisor.h>
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#include <asm/vmware.h>
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#define VMWARE_MAGIC 0x564D5868
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#define VMWARE_CMD_PCLK(nr) ((nr << 16) | 97)
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#define VMWARE_CMD_PCLK_GETTIME VMWARE_CMD_PCLK(0)
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static struct acpi_device *ptp_vmw_acpi_device;
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static struct ptp_clock *ptp_vmw_clock;
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static int ptp_vmw_pclk_read(u64 *ns)
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{
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u32 ret, nsec_hi, nsec_lo, unused1, unused2, unused3;
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asm volatile (VMWARE_HYPERCALL :
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"=a"(ret), "=b"(nsec_hi), "=c"(nsec_lo), "=d"(unused1),
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"=S"(unused2), "=D"(unused3) :
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"a"(VMWARE_MAGIC), "b"(0),
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"c"(VMWARE_CMD_PCLK_GETTIME), "d"(0) :
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"memory");
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if (ret == 0)
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*ns = ((u64)nsec_hi << 32) | nsec_lo;
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return ret;
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}
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/*
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* PTP clock ops.
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*/
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static int ptp_vmw_adjtime(struct ptp_clock_info *info, s64 delta)
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{
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return -EOPNOTSUPP;
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}
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static int ptp_vmw_adjfreq(struct ptp_clock_info *info, s32 delta)
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{
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return -EOPNOTSUPP;
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}
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static int ptp_vmw_gettime(struct ptp_clock_info *info, struct timespec64 *ts)
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{
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u64 ns;
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if (ptp_vmw_pclk_read(&ns) != 0)
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return -EIO;
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*ts = ns_to_timespec64(ns);
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return 0;
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}
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static int ptp_vmw_settime(struct ptp_clock_info *info,
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const struct timespec64 *ts)
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{
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return -EOPNOTSUPP;
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}
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static int ptp_vmw_enable(struct ptp_clock_info *info,
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struct ptp_clock_request *request, int on)
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{
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return -EOPNOTSUPP;
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}
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static struct ptp_clock_info ptp_vmw_clock_info = {
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.owner = THIS_MODULE,
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.name = "ptp_vmw",
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.max_adj = 0,
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.adjtime = ptp_vmw_adjtime,
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.adjfreq = ptp_vmw_adjfreq,
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.gettime64 = ptp_vmw_gettime,
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.settime64 = ptp_vmw_settime,
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.enable = ptp_vmw_enable,
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};
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/*
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* ACPI driver ops for VMware "precision clock" virtual device.
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*/
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static int ptp_vmw_acpi_add(struct acpi_device *device)
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{
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ptp_vmw_clock = ptp_clock_register(&ptp_vmw_clock_info, NULL);
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if (IS_ERR(ptp_vmw_clock)) {
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pr_err("failed to register ptp clock\n");
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return PTR_ERR(ptp_vmw_clock);
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}
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ptp_vmw_acpi_device = device;
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return 0;
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}
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static int ptp_vmw_acpi_remove(struct acpi_device *device)
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{
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ptp_clock_unregister(ptp_vmw_clock);
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return 0;
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}
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static const struct acpi_device_id ptp_vmw_acpi_device_ids[] = {
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{ "VMW0005", 0 },
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{ "", 0 },
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};
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MODULE_DEVICE_TABLE(acpi, ptp_vmw_acpi_device_ids);
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static struct acpi_driver ptp_vmw_acpi_driver = {
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.name = "ptp_vmw",
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.ids = ptp_vmw_acpi_device_ids,
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.ops = {
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.add = ptp_vmw_acpi_add,
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.remove = ptp_vmw_acpi_remove
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},
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.owner = THIS_MODULE
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};
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static int __init ptp_vmw_init(void)
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{
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if (x86_hyper_type != X86_HYPER_VMWARE)
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return -1;
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return acpi_bus_register_driver(&ptp_vmw_acpi_driver);
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}
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static void __exit ptp_vmw_exit(void)
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{
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acpi_bus_unregister_driver(&ptp_vmw_acpi_driver);
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}
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module_init(ptp_vmw_init);
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module_exit(ptp_vmw_exit);
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MODULE_DESCRIPTION("VMware virtual PTP clock driver");
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MODULE_AUTHOR("VMware, Inc.");
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MODULE_LICENSE("Dual BSD/GPL");
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