drivers/ptp/ptp_kvm_common.c

0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /*
0003  * Virtual PTP 1588 clock for use with KVM guests
0004  *
0005  * Copyright (C) 2017 Red Hat Inc.
0006  */
0007 #include <linux/device.h>
0008 #include <linux/err.h>
0009 #include <linux/init.h>
0010 #include <linux/kernel.h>
0011 #include <linux/slab.h>
0012 #include <linux/module.h>
0013 #include <linux/ptp_kvm.h>
0014 #include <uapi/linux/kvm_para.h>
0015 #include <asm/kvm_para.h>
0016 #include <uapi/asm/kvm_para.h>
0017
0018 #include <linux/ptp_clock_kernel.h>
0019
0020 struct kvm_ptp_clock {
0021     struct ptp_clock *ptp_clock;
0022     struct ptp_clock_info caps;
0023 };
0024
0025 static DEFINE_SPINLOCK(kvm_ptp_lock);
0026
0027 static int ptp_kvm_get_time_fn(ktime_t *device_time,
0028                    struct system_counterval_t *system_counter,
0029                    void *ctx)
0030 {
0031     long ret;
0032     u64 cycle;
0033     struct timespec64 tspec;
0034     struct clocksource *cs;
0035
0036     spin_lock(&kvm_ptp_lock);
0037
0038     preempt_disable_notrace();
0039     ret = kvm_arch_ptp_get_crosststamp(&cycle, &tspec, &cs);
0040     if (ret) {
0041         spin_unlock(&kvm_ptp_lock);
0042         preempt_enable_notrace();
0043         return ret;
0044     }
0045
0046     preempt_enable_notrace();
0047
0048     system_counter->cycles = cycle;
0049     system_counter->cs = cs;
0050
0051     *device_time = timespec64_to_ktime(tspec);
0052
0053     spin_unlock(&kvm_ptp_lock);
0054
0055     return 0;
0056 }
0057
0058 static int ptp_kvm_getcrosststamp(struct ptp_clock_info *ptp,
0059                   struct system_device_crosststamp *xtstamp)
0060 {
0061     return get_device_system_crosststamp(ptp_kvm_get_time_fn, NULL,
0062                          NULL, xtstamp);
0063 }
0064
0065 /*
0066  * PTP clock operations
0067  */
0068
0069 static int ptp_kvm_adjfreq(struct ptp_clock_info *ptp, s32 ppb)
0070 {
0071     return -EOPNOTSUPP;
0072 }
0073
0074 static int ptp_kvm_adjtime(struct ptp_clock_info *ptp, s64 delta)
0075 {
0076     return -EOPNOTSUPP;
0077 }
0078
0079 static int ptp_kvm_settime(struct ptp_clock_info *ptp,
0080                const struct timespec64 *ts)
0081 {
0082     return -EOPNOTSUPP;
0083 }
0084
0085 static int ptp_kvm_gettime(struct ptp_clock_info *ptp, struct timespec64 *ts)
0086 {
0087     long ret;
0088     struct timespec64 tspec;
0089
0090     spin_lock(&kvm_ptp_lock);
0091
0092     ret = kvm_arch_ptp_get_clock(&tspec);
0093     if (ret) {
0094         spin_unlock(&kvm_ptp_lock);
0095         return ret;
0096     }
0097
0098     spin_unlock(&kvm_ptp_lock);
0099
0100     memcpy(ts, &tspec, sizeof(struct timespec64));
0101
0102     return 0;
0103 }
0104
0105 static int ptp_kvm_enable(struct ptp_clock_info *ptp,
0106               struct ptp_clock_request *rq, int on)
0107 {
0108     return -EOPNOTSUPP;
0109 }
0110
0111 static const struct ptp_clock_info ptp_kvm_caps = {
0112     .owner      = THIS_MODULE,
0113     .name       = "KVM virtual PTP",
0114     .max_adj    = 0,
0115     .n_ext_ts   = 0,
0116     .n_pins     = 0,
0117     .pps        = 0,
0118     .adjfreq    = ptp_kvm_adjfreq,
0119     .adjtime    = ptp_kvm_adjtime,
0120     .gettime64  = ptp_kvm_gettime,
0121     .settime64  = ptp_kvm_settime,
0122     .enable     = ptp_kvm_enable,
0123     .getcrosststamp = ptp_kvm_getcrosststamp,
0124 };
0125
0126 /* module operations */
0127
0128 static struct kvm_ptp_clock kvm_ptp_clock;
0129
0130 static void __exit ptp_kvm_exit(void)
0131 {
0132     ptp_clock_unregister(kvm_ptp_clock.ptp_clock);
0133 }
0134
0135 static int __init ptp_kvm_init(void)
0136 {
0137     long ret;
0138
0139     ret = kvm_arch_ptp_init();
0140     if (ret) {
0141         if (ret != -EOPNOTSUPP)
0142             pr_err("fail to initialize ptp_kvm");
0143         return ret;
0144     }
0145
0146     kvm_ptp_clock.caps = ptp_kvm_caps;
0147
0148     kvm_ptp_clock.ptp_clock = ptp_clock_register(&kvm_ptp_clock.caps, NULL);
0149
0150     return PTR_ERR_OR_ZERO(kvm_ptp_clock.ptp_clock);
0151 }
0152
0153 module_init(ptp_kvm_init);
0154 module_exit(ptp_kvm_exit);
0155
0156 MODULE_AUTHOR("Marcelo Tosatti <mtosatti@redhat.com>");
0157 MODULE_DESCRIPTION("PTP clock using KVMCLOCK");
0158 MODULE_LICENSE("GPL");