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_MAGIC 0x564D5868
 18#define VMWARE_CMD_PCLK(nr) ((nr << 16) | 97)
 19#define VMWARE_CMD_PCLK_GETTIME VMWARE_CMD_PCLK(0)
 20
 21static struct acpi_device *ptp_vmw_acpi_device;
 22static struct ptp_clock *ptp_vmw_clock;
 23
 24
 25static int ptp_vmw_pclk_read(u64 *ns)
 26{
 27	u32 ret, nsec_hi, nsec_lo, unused1, unused2, unused3;
 28
 29	asm volatile (VMWARE_HYPERCALL :
 30		"=a"(ret), "=b"(nsec_hi), "=c"(nsec_lo), "=d"(unused1),
 31		"=S"(unused2), "=D"(unused3) :
 32		"a"(VMWARE_MAGIC), "b"(0),
 33		"c"(VMWARE_CMD_PCLK_GETTIME), "d"(0) :
 34		"memory");
 35
 36	if (ret == 0)
 37		*ns = ((u64)nsec_hi << 32) | nsec_lo;
 38	return ret;
 39}
 40
 41/*
 42 * PTP clock ops.
 43 */
 44
 45static int ptp_vmw_adjtime(struct ptp_clock_info *info, s64 delta)
 46{
 47	return -EOPNOTSUPP;
 48}
 49
 50static int ptp_vmw_adjfine(struct ptp_clock_info *info, long delta)
 51{
 52	return -EOPNOTSUPP;
 53}
 54
 55static int ptp_vmw_gettime(struct ptp_clock_info *info, struct timespec64 *ts)
 56{
 57	u64 ns;
 58
 59	if (ptp_vmw_pclk_read(&ns) != 0)
 60		return -EIO;
 61	*ts = ns_to_timespec64(ns);
 62	return 0;
 63}
 64
 65static int ptp_vmw_settime(struct ptp_clock_info *info,
 66			  const struct timespec64 *ts)
 67{
 68	return -EOPNOTSUPP;
 69}
 70
 71static int ptp_vmw_enable(struct ptp_clock_info *info,
 72			 struct ptp_clock_request *request, int on)
 73{
 74	return -EOPNOTSUPP;
 75}
 76
 77static struct ptp_clock_info ptp_vmw_clock_info = {
 78	.owner		= THIS_MODULE,
 79	.name		= "ptp_vmw",
 80	.max_adj	= 0,
 81	.adjtime	= ptp_vmw_adjtime,
 82	.adjfine	= ptp_vmw_adjfine,
 83	.gettime64	= ptp_vmw_gettime,
 84	.settime64	= ptp_vmw_settime,
 85	.enable		= ptp_vmw_enable,
 86};
 87
 88/*
 89 * ACPI driver ops for VMware "precision clock" virtual device.
 90 */
 91
 92static int ptp_vmw_acpi_add(struct acpi_device *device)
 93{
 94	ptp_vmw_clock = ptp_clock_register(&ptp_vmw_clock_info, NULL);
 95	if (IS_ERR(ptp_vmw_clock)) {
 96		pr_err("failed to register ptp clock\n");
 97		return PTR_ERR(ptp_vmw_clock);
 98	}
 99
100	ptp_vmw_acpi_device = device;
101	return 0;
102}
103
104static void ptp_vmw_acpi_remove(struct acpi_device *device)
105{
106	ptp_clock_unregister(ptp_vmw_clock);
107}
108
109static const struct acpi_device_id ptp_vmw_acpi_device_ids[] = {
110	{ "VMW0005", 0 },
111	{ "", 0 },
112};
113
114MODULE_DEVICE_TABLE(acpi, ptp_vmw_acpi_device_ids);
115
116static struct acpi_driver ptp_vmw_acpi_driver = {
117	.name = "ptp_vmw",
118	.ids = ptp_vmw_acpi_device_ids,
119	.ops = {
120		.add = ptp_vmw_acpi_add,
121		.remove	= ptp_vmw_acpi_remove
122	},
123	.owner	= THIS_MODULE
124};
125
126static int __init ptp_vmw_init(void)
127{
128	if (x86_hyper_type != X86_HYPER_VMWARE)
129		return -1;
130	return acpi_bus_register_driver(&ptp_vmw_acpi_driver);
131}
132
133static void __exit ptp_vmw_exit(void)
134{
135	acpi_bus_unregister_driver(&ptp_vmw_acpi_driver);
136}
137
138module_init(ptp_vmw_init);
139module_exit(ptp_vmw_exit);
140
141MODULE_DESCRIPTION("VMware virtual PTP clock driver");
142MODULE_AUTHOR("VMware, Inc.");
143MODULE_LICENSE("Dual BSD/GPL");