drivers/ptp/ptp_kvm_common.c

   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_adjfreq(struct ptp_clock_info *ptp, s32 ppb)
  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         .adjfreq        = ptp_kvm_adjfreq,
 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");