1// SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
  2/*
  3 * Copyright (C) 2020 VMware, Inc., Palo Alto, CA., USA
  4 *
  5 * PTP clock driver for VMware precision clock virtual device.
  6 */
  7
  8#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  9
 10#include <linux/acpi.h>
 11#include <linux/kernel.h>
 12#include <linux/module.h>
 13#include <linux/ptp_clock_kernel.h>
 14#include <asm/hypervisor.h>
 15#include <asm/vmware.h>
 16
 17#define VMWARE_CMD_PCLK(nr) ((nr << 16) | 97)
 18#define VMWARE_CMD_PCLK_GETTIME VMWARE_CMD_PCLK(0)
 19
 20static struct acpi_device *ptp_vmw_acpi_device;
 21static struct ptp_clock *ptp_vmw_clock;
 22
 23
 24static int ptp_vmw_pclk_read(u64 *ns)
 25{
 26	u32 ret, nsec_hi, nsec_lo;
 27
 28	ret = vmware_hypercall3(VMWARE_CMD_PCLK_GETTIME, 0,
 29				&nsec_hi, &nsec_lo);
 30	if (ret == 0)
 31		*ns = ((u64)nsec_hi << 32) | nsec_lo;
 32	return ret;
 33}
 34
 35/*
 36 * PTP clock ops.
 37 */
 38
 39static int ptp_vmw_adjtime(struct ptp_clock_info *info, s64 delta)
 40{
 41	return -EOPNOTSUPP;
 42}
 43
 44static int ptp_vmw_adjfine(struct ptp_clock_info *info, long delta)
 45{
 46	return -EOPNOTSUPP;
 47}
 48
 49static int ptp_vmw_gettime(struct ptp_clock_info *info, struct timespec64 *ts)
 50{
 51	u64 ns;
 52
 53	if (ptp_vmw_pclk_read(&ns) != 0)
 54		return -EIO;
 55	*ts = ns_to_timespec64(ns);
 56	return 0;
 57}
 58
 59static int ptp_vmw_settime(struct ptp_clock_info *info,
 60			  const struct timespec64 *ts)
 61{
 62	return -EOPNOTSUPP;
 63}
 64
 65static int ptp_vmw_enable(struct ptp_clock_info *info,
 66			 struct ptp_clock_request *request, int on)
 67{
 68	return -EOPNOTSUPP;
 69}
 70
 71static struct ptp_clock_info ptp_vmw_clock_info = {
 72	.owner		= THIS_MODULE,
 73	.name		= "ptp_vmw",
 74	.max_adj	= 0,
 75	.adjtime	= ptp_vmw_adjtime,
 76	.adjfine	= ptp_vmw_adjfine,
 77	.gettime64	= ptp_vmw_gettime,
 78	.settime64	= ptp_vmw_settime,
 79	.enable		= ptp_vmw_enable,
 80};
 81
 82/*
 83 * ACPI driver ops for VMware "precision clock" virtual device.
 84 */
 85
 86static int ptp_vmw_acpi_add(struct acpi_device *device)
 87{
 88	ptp_vmw_clock = ptp_clock_register(&ptp_vmw_clock_info, NULL);
 89	if (IS_ERR(ptp_vmw_clock)) {
 90		pr_err("failed to register ptp clock\n");
 91		return PTR_ERR(ptp_vmw_clock);
 92	}
 93
 94	ptp_vmw_acpi_device = device;
 95	return 0;
 96}
 97
 98static void ptp_vmw_acpi_remove(struct acpi_device *device)
 99{
100	ptp_clock_unregister(ptp_vmw_clock);
101}
102
103static const struct acpi_device_id ptp_vmw_acpi_device_ids[] = {
104	{ "VMW0005", 0 },
105	{ "", 0 },
106};
107
108MODULE_DEVICE_TABLE(acpi, ptp_vmw_acpi_device_ids);
109
110static struct acpi_driver ptp_vmw_acpi_driver = {
111	.name = "ptp_vmw",
112	.ids = ptp_vmw_acpi_device_ids,
113	.ops = {
114		.add = ptp_vmw_acpi_add,
115		.remove	= ptp_vmw_acpi_remove
116	},
117};
118
119static int __init ptp_vmw_init(void)
120{
121	if (x86_hyper_type != X86_HYPER_VMWARE)
122		return -1;
123	return acpi_bus_register_driver(&ptp_vmw_acpi_driver);
124}
125
126static void __exit ptp_vmw_exit(void)
127{
128	acpi_bus_unregister_driver(&ptp_vmw_acpi_driver);
129}
130
131module_init(ptp_vmw_init);
132module_exit(ptp_vmw_exit);
133
134MODULE_DESCRIPTION("VMware virtual PTP clock driver");
135MODULE_AUTHOR("VMware, Inc.");
136MODULE_LICENSE("Dual BSD/GPL");