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: &ns) != 0)
60 return -EIO;
61 *ts = ns_to_timespec64(nsec: 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(info: &ptp_vmw_clock_info, NULL);
95 if (IS_ERR(ptr: ptp_vmw_clock)) {
96 pr_err("failed to register ptp clock\n");
97 return PTR_ERR(ptr: 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: 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(driver: &ptp_vmw_acpi_driver);
131}
132
133static void __exit ptp_vmw_exit(void)
134{
135 acpi_bus_unregister_driver(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");
144

source code of linux/drivers/ptp/ptp_vmw.c