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
|
|
/*
|
|
* Copyright (C) 2020 VMware, Inc., Palo Alto, CA., USA
|
|
*
|
|
* PTP clock driver for VMware precision clock virtual device.
|
|
*/
|
|
|
|
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
|
|
|
|
#include <linux/acpi.h>
|
|
#include <linux/kernel.h>
|
|
#include <linux/module.h>
|
|
#include <linux/ptp_clock_kernel.h>
|
|
#include <asm/hypervisor.h>
|
|
#include <asm/vmware.h>
|
|
|
|
#define VMWARE_MAGIC 0x564D5868
|
|
#define VMWARE_CMD_PCLK(nr) ((nr << 16) | 97)
|
|
#define VMWARE_CMD_PCLK_GETTIME VMWARE_CMD_PCLK(0)
|
|
|
|
static struct acpi_device *ptp_vmw_acpi_device;
|
|
static struct ptp_clock *ptp_vmw_clock;
|
|
|
|
|
|
static int ptp_vmw_pclk_read(u64 *ns)
|
|
{
|
|
u32 ret, nsec_hi, nsec_lo, unused1, unused2, unused3;
|
|
|
|
asm volatile (VMWARE_HYPERCALL :
|
|
"=a"(ret), "=b"(nsec_hi), "=c"(nsec_lo), "=d"(unused1),
|
|
"=S"(unused2), "=D"(unused3) :
|
|
"a"(VMWARE_MAGIC), "b"(0),
|
|
"c"(VMWARE_CMD_PCLK_GETTIME), "d"(0) :
|
|
"memory");
|
|
|
|
if (ret == 0)
|
|
*ns = ((u64)nsec_hi << 32) | nsec_lo;
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* PTP clock ops.
|
|
*/
|
|
|
|
static int ptp_vmw_adjtime(struct ptp_clock_info *info, s64 delta)
|
|
{
|
|
return -EOPNOTSUPP;
|
|
}
|
|
|
|
static int ptp_vmw_adjfreq(struct ptp_clock_info *info, s32 delta)
|
|
{
|
|
return -EOPNOTSUPP;
|
|
}
|
|
|
|
static int ptp_vmw_gettime(struct ptp_clock_info *info, struct timespec64 *ts)
|
|
{
|
|
u64 ns;
|
|
|
|
if (ptp_vmw_pclk_read(&ns) != 0)
|
|
return -EIO;
|
|
*ts = ns_to_timespec64(ns);
|
|
return 0;
|
|
}
|
|
|
|
static int ptp_vmw_settime(struct ptp_clock_info *info,
|
|
const struct timespec64 *ts)
|
|
{
|
|
return -EOPNOTSUPP;
|
|
}
|
|
|
|
static int ptp_vmw_enable(struct ptp_clock_info *info,
|
|
struct ptp_clock_request *request, int on)
|
|
{
|
|
return -EOPNOTSUPP;
|
|
}
|
|
|
|
static struct ptp_clock_info ptp_vmw_clock_info = {
|
|
.owner = THIS_MODULE,
|
|
.name = "ptp_vmw",
|
|
.max_adj = 0,
|
|
.adjtime = ptp_vmw_adjtime,
|
|
.adjfreq = ptp_vmw_adjfreq,
|
|
.gettime64 = ptp_vmw_gettime,
|
|
.settime64 = ptp_vmw_settime,
|
|
.enable = ptp_vmw_enable,
|
|
};
|
|
|
|
/*
|
|
* ACPI driver ops for VMware "precision clock" virtual device.
|
|
*/
|
|
|
|
static int ptp_vmw_acpi_add(struct acpi_device *device)
|
|
{
|
|
ptp_vmw_clock = ptp_clock_register(&ptp_vmw_clock_info, NULL);
|
|
if (IS_ERR(ptp_vmw_clock)) {
|
|
pr_err("failed to register ptp clock\n");
|
|
return PTR_ERR(ptp_vmw_clock);
|
|
}
|
|
|
|
ptp_vmw_acpi_device = device;
|
|
return 0;
|
|
}
|
|
|
|
static int ptp_vmw_acpi_remove(struct acpi_device *device)
|
|
{
|
|
ptp_clock_unregister(ptp_vmw_clock);
|
|
return 0;
|
|
}
|
|
|
|
static const struct acpi_device_id ptp_vmw_acpi_device_ids[] = {
|
|
{ "VMW0005", 0 },
|
|
{ "", 0 },
|
|
};
|
|
|
|
MODULE_DEVICE_TABLE(acpi, ptp_vmw_acpi_device_ids);
|
|
|
|
static struct acpi_driver ptp_vmw_acpi_driver = {
|
|
.name = "ptp_vmw",
|
|
.ids = ptp_vmw_acpi_device_ids,
|
|
.ops = {
|
|
.add = ptp_vmw_acpi_add,
|
|
.remove = ptp_vmw_acpi_remove
|
|
},
|
|
.owner = THIS_MODULE
|
|
};
|
|
|
|
static int __init ptp_vmw_init(void)
|
|
{
|
|
if (x86_hyper_type != X86_HYPER_VMWARE)
|
|
return -1;
|
|
return acpi_bus_register_driver(&ptp_vmw_acpi_driver);
|
|
}
|
|
|
|
static void __exit ptp_vmw_exit(void)
|
|
{
|
|
acpi_bus_unregister_driver(&ptp_vmw_acpi_driver);
|
|
}
|
|
|
|
module_init(ptp_vmw_init);
|
|
module_exit(ptp_vmw_exit);
|
|
|
|
MODULE_DESCRIPTION("VMware virtual PTP clock driver");
|
|
MODULE_AUTHOR("VMware, Inc.");
|
|
MODULE_LICENSE("Dual BSD/GPL");
|