xref: /openbmc/linux/drivers/ptp/ptp_vmw.c (revision 6c0eb5ba)
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_adjfine(struct ptp_clock_info * info,long delta)50 static int ptp_vmw_adjfine(struct ptp_clock_info *info, long 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 	.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 
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 void ptp_vmw_acpi_remove(struct acpi_device *device)
105 {
106 	ptp_clock_unregister(ptp_vmw_clock);
107 }
108 
109 static const struct acpi_device_id ptp_vmw_acpi_device_ids[] = {
110 	{ "VMW0005", 0 },
111 	{ "", 0 },
112 };
113 
114 MODULE_DEVICE_TABLE(acpi, ptp_vmw_acpi_device_ids);
115 
116 static 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 
ptp_vmw_init(void)126 static 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 
ptp_vmw_exit(void)133 static void __exit ptp_vmw_exit(void)
134 {
135 	acpi_bus_unregister_driver(&ptp_vmw_acpi_driver);
136 }
137 
138 module_init(ptp_vmw_init);
139 module_exit(ptp_vmw_exit);
140 
141 MODULE_DESCRIPTION("VMware virtual PTP clock driver");
142 MODULE_AUTHOR("VMware, Inc.");
143 MODULE_LICENSE("Dual BSD/GPL");
144