// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Virtual PTP 1588 clock for use with KVM guests
 *
 * Copyright (C) 2017 Red Hat Inc.
 */
#include <linux/device.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/ptp_kvm.h>
#include <uapi/linux/kvm_para.h>
#include <asm/kvm_para.h>
#include <uapi/asm/kvm_para.h>

#include <linux/ptp_clock_kernel.h>

struct kvm_ptp_clock {
        struct ptp_clock *ptp_clock;
        struct ptp_clock_info caps;
};

static DEFINE_SPINLOCK(kvm_ptp_lock);

static int ptp_kvm_get_time_fn(ktime_t *device_time,
                               struct system_counterval_t *system_counter,
                               void *ctx)
{
        enum clocksource_ids cs_id;
        struct timespec64 tspec;
        u64 cycle;
        int ret;

        spin_lock(&kvm_ptp_lock);

        preempt_disable_notrace();
        ret = kvm_arch_ptp_get_crosststamp(&cycle, &tspec, &cs_id);
        if (ret) {
                spin_unlock(&kvm_ptp_lock);
                preempt_enable_notrace();
                return ret;
        }

        preempt_enable_notrace();

        system_counter->cycles = cycle;
        system_counter->cs_id = cs_id;

        *device_time = timespec64_to_ktime(tspec);

        spin_unlock(&kvm_ptp_lock);

        return 0;
}

static int ptp_kvm_getcrosststamp(struct ptp_clock_info *ptp,
                                  struct system_device_crosststamp *xtstamp)
{
        return get_device_system_crosststamp(ptp_kvm_get_time_fn, NULL,
                                             NULL, xtstamp);
}

/*
 * PTP clock operations
 */

static int ptp_kvm_adjfine(struct ptp_clock_info *ptp, long delta)
{
        return -EOPNOTSUPP;
}

static int ptp_kvm_adjtime(struct ptp_clock_info *ptp, s64 delta)
{
        return -EOPNOTSUPP;
}

static int ptp_kvm_settime(struct ptp_clock_info *ptp,
                           const struct timespec64 *ts)
{
        return -EOPNOTSUPP;
}

static int ptp_kvm_gettime(struct ptp_clock_info *ptp, struct timespec64 *ts)
{
        long ret;
        struct timespec64 tspec;

        spin_lock(&kvm_ptp_lock);

        ret = kvm_arch_ptp_get_clock(&tspec);
        if (ret) {
                spin_unlock(&kvm_ptp_lock);
                return ret;
        }

        spin_unlock(&kvm_ptp_lock);

        memcpy(ts, &tspec, sizeof(struct timespec64));

        return 0;
}

static int ptp_kvm_enable(struct ptp_clock_info *ptp,
                          struct ptp_clock_request *rq, int on)
{
        return -EOPNOTSUPP;
}

static const struct ptp_clock_info ptp_kvm_caps = {
        .owner          = THIS_MODULE,
        .name           = "KVM virtual PTP",
        .max_adj        = 0,
        .n_ext_ts       = 0,
        .n_pins         = 0,
        .pps            = 0,
        .adjfine        = ptp_kvm_adjfine,
        .adjtime        = ptp_kvm_adjtime,
        .gettime64      = ptp_kvm_gettime,
        .settime64      = ptp_kvm_settime,
        .enable         = ptp_kvm_enable,
        .getcrosststamp = ptp_kvm_getcrosststamp,
};

/* module operations */

static struct kvm_ptp_clock kvm_ptp_clock;

static void __exit ptp_kvm_exit(void)
{
        ptp_clock_unregister(kvm_ptp_clock.ptp_clock);
        kvm_arch_ptp_exit();
}

static int __init ptp_kvm_init(void)
{
        long ret;

        ret = kvm_arch_ptp_init();
        if (ret) {
                if (ret != -EOPNOTSUPP)
                        pr_err("fail to initialize ptp_kvm");
                return ret;
        }

        kvm_ptp_clock.caps = ptp_kvm_caps;

        kvm_ptp_clock.ptp_clock = ptp_clock_register(&kvm_ptp_clock.caps, NULL);

        return PTR_ERR_OR_ZERO(kvm_ptp_clock.ptp_clock);
}

module_init(ptp_kvm_init);
module_exit(ptp_kvm_exit);

MODULE_AUTHOR("Marcelo Tosatti <mtosatti@redhat.com>");
MODULE_DESCRIPTION("PTP clock using KVMCLOCK");
MODULE_LICENSE("GPL");