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
21 static struct acpi_device *ptp_vmw_acpi_device;
22 static struct ptp_clock *ptp_vmw_clock;
23
24
ptp_vmw_pclk_read(u64 * ns)25 static 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
ptp_vmw_adjtime(struct ptp_clock_info * info,s64 delta)45 static int ptp_vmw_adjtime(struct ptp_clock_info *info, s64 delta)
46 {
47 return -EOPNOTSUPP;
48 }
49
ptp_vmw_adjfreq(struct ptp_clock_info * info,s32 delta)50 static int ptp_vmw_adjfreq(struct ptp_clock_info *info, s32 delta)
51 {
52 return -EOPNOTSUPP;
53 }
54
ptp_vmw_gettime(struct ptp_clock_info * info,struct timespec64 * ts)55 static 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
ptp_vmw_settime(struct ptp_clock_info * info,const struct timespec64 * ts)65 static int ptp_vmw_settime(struct ptp_clock_info *info,
66 const struct timespec64 *ts)
67 {
68 return -EOPNOTSUPP;
69 }
70
ptp_vmw_enable(struct ptp_clock_info * info,struct ptp_clock_request * request,int on)71 static int ptp_vmw_enable(struct ptp_clock_info *info,
72 struct ptp_clock_request *request, int on)
73 {
74 return -EOPNOTSUPP;
75 }
76
77 static 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 .adjfreq = ptp_vmw_adjfreq,
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
ptp_vmw_acpi_add(struct acpi_device * device)92 static 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
ptp_vmw_acpi_remove(struct acpi_device * device)104 static int ptp_vmw_acpi_remove(struct acpi_device *device)
105 {
106 ptp_clock_unregister(ptp_vmw_clock);
107 return 0;
108 }
109
110 static const struct acpi_device_id ptp_vmw_acpi_device_ids[] = {
111 { "VMW0005", 0 },
112 { "", 0 },
113 };
114
115 MODULE_DEVICE_TABLE(acpi, ptp_vmw_acpi_device_ids);
116
117 static struct acpi_driver ptp_vmw_acpi_driver = {
118 .name = "ptp_vmw",
119 .ids = ptp_vmw_acpi_device_ids,
120 .ops = {
121 .add = ptp_vmw_acpi_add,
122 .remove = ptp_vmw_acpi_remove
123 },
124 .owner = THIS_MODULE
125 };
126
ptp_vmw_init(void)127 static int __init ptp_vmw_init(void)
128 {
129 if (x86_hyper_type != X86_HYPER_VMWARE)
130 return -1;
131 return acpi_bus_register_driver(&ptp_vmw_acpi_driver);
132 }
133
ptp_vmw_exit(void)134 static void __exit ptp_vmw_exit(void)
135 {
136 acpi_bus_unregister_driver(&ptp_vmw_acpi_driver);
137 }
138
139 module_init(ptp_vmw_init);
140 module_exit(ptp_vmw_exit);
141
142 MODULE_DESCRIPTION("VMware virtual PTP clock driver");
143 MODULE_AUTHOR("VMware, Inc.");
144 MODULE_LICENSE("Dual BSD/GPL");
145