xref: /openbmc/linux/drivers/ptp/ptp_kvm_common.c (revision 5efb685b)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Virtual PTP 1588 clock for use with KVM guests
4  *
5  * Copyright (C) 2017 Red Hat Inc.
6  */
7 #include <linux/device.h>
8 #include <linux/err.h>
9 #include <linux/init.h>
10 #include <linux/kernel.h>
11 #include <linux/slab.h>
12 #include <linux/module.h>
13 #include <linux/ptp_kvm.h>
14 #include <uapi/linux/kvm_para.h>
15 #include <asm/kvm_para.h>
16 #include <uapi/asm/kvm_para.h>
17 
18 #include <linux/ptp_clock_kernel.h>
19 
20 struct kvm_ptp_clock {
21 	struct ptp_clock *ptp_clock;
22 	struct ptp_clock_info caps;
23 };
24 
25 static DEFINE_SPINLOCK(kvm_ptp_lock);
26 
27 static int ptp_kvm_get_time_fn(ktime_t *device_time,
28 			       struct system_counterval_t *system_counter,
29 			       void *ctx)
30 {
31 	long ret;
32 	u64 cycle;
33 	struct timespec64 tspec;
34 	struct clocksource *cs;
35 
36 	spin_lock(&kvm_ptp_lock);
37 
38 	preempt_disable_notrace();
39 	ret = kvm_arch_ptp_get_crosststamp(&cycle, &tspec, &cs);
40 	if (ret) {
41 		spin_unlock(&kvm_ptp_lock);
42 		preempt_enable_notrace();
43 		return ret;
44 	}
45 
46 	preempt_enable_notrace();
47 
48 	system_counter->cycles = cycle;
49 	system_counter->cs = cs;
50 
51 	*device_time = timespec64_to_ktime(tspec);
52 
53 	spin_unlock(&kvm_ptp_lock);
54 
55 	return 0;
56 }
57 
58 static int ptp_kvm_getcrosststamp(struct ptp_clock_info *ptp,
59 				  struct system_device_crosststamp *xtstamp)
60 {
61 	return get_device_system_crosststamp(ptp_kvm_get_time_fn, NULL,
62 					     NULL, xtstamp);
63 }
64 
65 /*
66  * PTP clock operations
67  */
68 
69 static int ptp_kvm_adjfine(struct ptp_clock_info *ptp, long delta)
70 {
71 	return -EOPNOTSUPP;
72 }
73 
74 static int ptp_kvm_adjtime(struct ptp_clock_info *ptp, s64 delta)
75 {
76 	return -EOPNOTSUPP;
77 }
78 
79 static int ptp_kvm_settime(struct ptp_clock_info *ptp,
80 			   const struct timespec64 *ts)
81 {
82 	return -EOPNOTSUPP;
83 }
84 
85 static int ptp_kvm_gettime(struct ptp_clock_info *ptp, struct timespec64 *ts)
86 {
87 	long ret;
88 	struct timespec64 tspec;
89 
90 	spin_lock(&kvm_ptp_lock);
91 
92 	ret = kvm_arch_ptp_get_clock(&tspec);
93 	if (ret) {
94 		spin_unlock(&kvm_ptp_lock);
95 		return ret;
96 	}
97 
98 	spin_unlock(&kvm_ptp_lock);
99 
100 	memcpy(ts, &tspec, sizeof(struct timespec64));
101 
102 	return 0;
103 }
104 
105 static int ptp_kvm_enable(struct ptp_clock_info *ptp,
106 			  struct ptp_clock_request *rq, int on)
107 {
108 	return -EOPNOTSUPP;
109 }
110 
111 static const struct ptp_clock_info ptp_kvm_caps = {
112 	.owner		= THIS_MODULE,
113 	.name		= "KVM virtual PTP",
114 	.max_adj	= 0,
115 	.n_ext_ts	= 0,
116 	.n_pins		= 0,
117 	.pps		= 0,
118 	.adjfine	= ptp_kvm_adjfine,
119 	.adjtime	= ptp_kvm_adjtime,
120 	.gettime64	= ptp_kvm_gettime,
121 	.settime64	= ptp_kvm_settime,
122 	.enable		= ptp_kvm_enable,
123 	.getcrosststamp = ptp_kvm_getcrosststamp,
124 };
125 
126 /* module operations */
127 
128 static struct kvm_ptp_clock kvm_ptp_clock;
129 
130 static void __exit ptp_kvm_exit(void)
131 {
132 	ptp_clock_unregister(kvm_ptp_clock.ptp_clock);
133 }
134 
135 static int __init ptp_kvm_init(void)
136 {
137 	long ret;
138 
139 	ret = kvm_arch_ptp_init();
140 	if (ret) {
141 		if (ret != -EOPNOTSUPP)
142 			pr_err("fail to initialize ptp_kvm");
143 		return ret;
144 	}
145 
146 	kvm_ptp_clock.caps = ptp_kvm_caps;
147 
148 	kvm_ptp_clock.ptp_clock = ptp_clock_register(&kvm_ptp_clock.caps, NULL);
149 
150 	return PTR_ERR_OR_ZERO(kvm_ptp_clock.ptp_clock);
151 }
152 
153 module_init(ptp_kvm_init);
154 module_exit(ptp_kvm_exit);
155 
156 MODULE_AUTHOR("Marcelo Tosatti <mtosatti@redhat.com>");
157 MODULE_DESCRIPTION("PTP clock using KVMCLOCK");
158 MODULE_LICENSE("GPL");
159