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
 20struct kvm_ptp_clock {
 21	struct ptp_clock *ptp_clock;
 22	struct ptp_clock_info caps;
 23};
 24
 25static DEFINE_SPINLOCK(kvm_ptp_lock);
 26
 27static int ptp_kvm_get_time_fn(ktime_t *device_time,
 28			       struct system_counterval_t *system_counter,
 29			       void *ctx)
 30{
 31	enum clocksource_ids cs_id;
 32	struct timespec64 tspec;
 33	u64 cycle;
 34	int ret;
 35
 36	spin_lock(&kvm_ptp_lock);
 37
 38	preempt_disable_notrace();
 39	ret = kvm_arch_ptp_get_crosststamp(&cycle, &tspec, &cs_id);
 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_id = cs_id;
 50
 51	*device_time = timespec64_to_ktime(tspec);
 52
 53	spin_unlock(&kvm_ptp_lock);
 54
 55	return 0;
 56}
 57
 58static 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
 69static int ptp_kvm_adjfine(struct ptp_clock_info *ptp, long delta)
 70{
 71	return -EOPNOTSUPP;
 72}
 73
 74static int ptp_kvm_adjtime(struct ptp_clock_info *ptp, s64 delta)
 75{
 76	return -EOPNOTSUPP;
 77}
 78
 79static int ptp_kvm_settime(struct ptp_clock_info *ptp,
 80			   const struct timespec64 *ts)
 81{
 82	return -EOPNOTSUPP;
 83}
 84
 85static 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
105static int ptp_kvm_enable(struct ptp_clock_info *ptp,
106			  struct ptp_clock_request *rq, int on)
107{
108	return -EOPNOTSUPP;
109}
110
111static 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
128static struct kvm_ptp_clock kvm_ptp_clock;
129
130static void __exit ptp_kvm_exit(void)
131{
132	ptp_clock_unregister(kvm_ptp_clock.ptp_clock);
133	kvm_arch_ptp_exit();
134}
135
136static int __init ptp_kvm_init(void)
137{
138	long ret;
139
140	ret = kvm_arch_ptp_init();
141	if (ret) {
142		if (ret != -EOPNOTSUPP)
143			pr_err("fail to initialize ptp_kvm");
144		return ret;
145	}
146
147	kvm_ptp_clock.caps = ptp_kvm_caps;
148
149	kvm_ptp_clock.ptp_clock = ptp_clock_register(&kvm_ptp_clock.caps, NULL);
150
151	return PTR_ERR_OR_ZERO(kvm_ptp_clock.ptp_clock);
152}
153
154module_init(ptp_kvm_init);
155module_exit(ptp_kvm_exit);
156
157MODULE_AUTHOR("Marcelo Tosatti <mtosatti@redhat.com>");
158MODULE_DESCRIPTION("PTP clock using KVMCLOCK");
159MODULE_LICENSE("GPL");