// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * PTP 1588 clock support
 *
 * Copyright (C) 2010 OMICRON electronics GmbH
 */
#include <linux/device.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/posix-clock.h>
#include <linux/pps_kernel.h>
#include <linux/property.h>
#include <linux/slab.h>
#include <linux/syscalls.h>
#include <linux/uaccess.h>
#include <linux/debugfs.h>
#include <linux/xarray.h>
#include <uapi/linux/sched/types.h>

#include "ptp_private.h"

#define PTP_MAX_ALARMS 4
#define PTP_PPS_DEFAULTS (PPS_CAPTUREASSERT | PPS_OFFSETASSERT)
#define PTP_PPS_EVENT PPS_CAPTUREASSERT
#define PTP_PPS_MODE (PTP_PPS_DEFAULTS | PPS_CANWAIT | PPS_TSFMT_TSPEC)

const struct class ptp_class = {
        .name = "ptp",
        .dev_groups = ptp_groups
};

/* private globals */

static dev_t ptp_devt;

static DEFINE_XARRAY_ALLOC(ptp_clocks_map);

/* time stamp event queue operations */

static inline int queue_free(struct timestamp_event_queue *q)
{
        return PTP_MAX_TIMESTAMPS - queue_cnt(q) - 1;
}

static void enqueue_external_timestamp(struct timestamp_event_queue *queue,
                                       struct ptp_clock_event *src)
{
        struct ptp_extts_event *dst;
        struct timespec64 offset_ts;
        unsigned long flags;
        s64 seconds;
        u32 remainder;

        if (src->type == PTP_CLOCK_EXTTS) {
                seconds = div_u64_rem(src->timestamp, 1000000000, &remainder);
        } else if (src->type == PTP_CLOCK_EXTOFF) {
                offset_ts = ns_to_timespec64(src->offset);
                seconds = offset_ts.tv_sec;
                remainder = offset_ts.tv_nsec;
        } else {
                WARN(1, "%s: unknown type %d\n", __func__, src->type);
                return;
        }

        spin_lock_irqsave(&queue->lock, flags);

        dst = &queue->buf[queue->tail];
        dst->index = src->index;
        dst->flags = PTP_EXTTS_EVENT_VALID;
        dst->t.sec = seconds;
        dst->t.nsec = remainder;
        if (src->type == PTP_CLOCK_EXTOFF)
                dst->flags |= PTP_EXT_OFFSET;

        /* Both WRITE_ONCE() are paired with READ_ONCE() in queue_cnt() */
        if (!queue_free(queue))
                WRITE_ONCE(queue->head, (queue->head + 1) % PTP_MAX_TIMESTAMPS);

        WRITE_ONCE(queue->tail, (queue->tail + 1) % PTP_MAX_TIMESTAMPS);

        spin_unlock_irqrestore(&queue->lock, flags);
}

/* posix clock implementation */

static int ptp_clock_getres(struct posix_clock *pc, struct timespec64 *tp)
{
        tp->tv_sec = 0;
        tp->tv_nsec = 1;
        return 0;
}

static int ptp_clock_settime(struct posix_clock *pc, const struct timespec64 *tp)
{
        struct ptp_clock *ptp = container_of(pc, struct ptp_clock, clock);

        if (ptp_clock_freerun(ptp)) {
                pr_err_ratelimited("ptp: physical clock is free running\n");
                return -EBUSY;
        }

        if (!timespec64_valid_settod(tp))
                return -EINVAL;

        return  ptp->info->settime64(ptp->info, tp);
}

static int ptp_clock_gettime(struct posix_clock *pc, struct timespec64 *tp)
{
        struct ptp_clock *ptp = container_of(pc, struct ptp_clock, clock);
        int err;

        if (ptp->info->gettimex64)
                err = ptp->info->gettimex64(ptp->info, tp, NULL);
        else
                err = ptp->info->gettime64(ptp->info, tp);
        return err;
}

static int ptp_clock_adjtime(struct posix_clock *pc, struct __kernel_timex *tx)
{
        struct ptp_clock *ptp = container_of(pc, struct ptp_clock, clock);
        struct ptp_clock_info *ops;
        int err = -EOPNOTSUPP;

        if (tx->modes & (ADJ_SETOFFSET | ADJ_FREQUENCY | ADJ_OFFSET) &&
            ptp_clock_freerun(ptp)) {
                pr_err("ptp: physical clock is free running\n");
                return -EBUSY;
        }

        ops = ptp->info;

        if (tx->modes & ADJ_SETOFFSET) {
                struct timespec64 ts, ts2;
                ktime_t kt;
                s64 delta;

                ts.tv_sec  = tx->time.tv_sec;
                ts.tv_nsec = tx->time.tv_usec;

                if (!(tx->modes & ADJ_NANO))
                        ts.tv_nsec *= 1000;

                if ((unsigned long) ts.tv_nsec >= NSEC_PER_SEC)
                        return -EINVAL;

                /* Make sure the offset is valid */
                err = ptp_clock_gettime(pc, &ts2);
                if (err)
                        return err;
                ts2 = timespec64_add(ts2, ts);
                if (!timespec64_valid_settod(&ts2))
                        return -EINVAL;

                kt = timespec64_to_ktime(ts);
                delta = ktime_to_ns(kt);
                err = ops->adjtime(ops, delta);
        } else if (tx->modes & ADJ_FREQUENCY) {
                long ppb = scaled_ppm_to_ppb(tx->freq);
                if (ppb > ops->max_adj || ppb < -ops->max_adj)
                        return -ERANGE;
                err = ops->adjfine(ops, tx->freq);
                if (!err)
                        ptp->dialed_frequency = tx->freq;
        } else if (tx->modes & ADJ_OFFSET) {
                if (ops->adjphase) {
                        s32 max_phase_adj = ops->getmaxphase(ops);
                        s32 offset = tx->offset;

                        if (!(tx->modes & ADJ_NANO))
                                offset *= NSEC_PER_USEC;

                        if (offset > max_phase_adj || offset < -max_phase_adj)
                                return -ERANGE;

                        err = ops->adjphase(ops, offset);
                }
        } else if (tx->modes == 0) {
                tx->freq = ptp->dialed_frequency;
                err = 0;
        }

        return err;
}

static struct posix_clock_operations ptp_clock_ops = {
        .owner          = THIS_MODULE,
        .clock_adjtime  = ptp_clock_adjtime,
        .clock_gettime  = ptp_clock_gettime,
        .clock_getres   = ptp_clock_getres,
        .clock_settime  = ptp_clock_settime,
        .ioctl          = ptp_ioctl,
        .open           = ptp_open,
        .release        = ptp_release,
        .poll           = ptp_poll,
        .read           = ptp_read,
};

static void ptp_clock_release(struct device *dev)
{
        struct ptp_clock *ptp = container_of(dev, struct ptp_clock, dev);
        struct timestamp_event_queue *tsevq;
        unsigned long flags;

        ptp_cleanup_pin_groups(ptp);
        kfree(ptp->vclock_index);
        mutex_destroy(&ptp->pincfg_mux);
        mutex_destroy(&ptp->n_vclocks_mux);
        /* Delete first entry */
        spin_lock_irqsave(&ptp->tsevqs_lock, flags);
        tsevq = list_first_entry(&ptp->tsevqs, struct timestamp_event_queue,
                                 qlist);
        list_del(&tsevq->qlist);
        spin_unlock_irqrestore(&ptp->tsevqs_lock, flags);
        bitmap_free(tsevq->mask);
        kfree(tsevq);
        debugfs_remove(ptp->debugfs_root);
        xa_erase(&ptp_clocks_map, ptp->index);
        kfree(ptp);
}

static int ptp_getcycles64(struct ptp_clock_info *info, struct timespec64 *ts)
{
        if (info->getcyclesx64)
                return info->getcyclesx64(info, ts, NULL);
        else
                return info->gettime64(info, ts);
}

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

static void ptp_aux_kworker(struct kthread_work *work)
{
        struct ptp_clock *ptp = container_of(work, struct ptp_clock,
                                             aux_work.work);
        struct ptp_clock_info *info = ptp->info;
        long delay;

        delay = info->do_aux_work(info);

        if (delay >= 0)
                kthread_queue_delayed_work(ptp->kworker, &ptp->aux_work, delay);
}

static ssize_t ptp_n_perout_loopback_read(struct file *filep,
                                          char __user *buffer,
                                          size_t count, loff_t *pos)
{
        struct ptp_clock *ptp = filep->private_data;
        char buf[12] = {};

        snprintf(buf, sizeof(buf), "%d\n", ptp->info->n_per_lp);

        return simple_read_from_buffer(buffer, count, pos, buf, strlen(buf));
}

static const struct file_operations ptp_n_perout_loopback_fops = {
        .owner  = THIS_MODULE,
        .open   = simple_open,
        .read   = ptp_n_perout_loopback_read,
};

static ssize_t ptp_perout_loopback_write(struct file *filep,
                                         const char __user *buffer,
                                         size_t count, loff_t *ppos)
{
        struct ptp_clock *ptp = filep->private_data;
        struct ptp_clock_info *ops = ptp->info;
        unsigned int index, enable;
        int len, cnt, err;
        char buf[32] = {};

        if (*ppos || !count)
                return -EINVAL;

        if (count >= sizeof(buf))
                return -ENOSPC;

        len = simple_write_to_buffer(buf, sizeof(buf) - 1,
                                     ppos, buffer, count);
        if (len < 0)
                return len;

        buf[len] = '\0';
        cnt = sscanf(buf, "%u %u", &index, &enable);
        if (cnt != 2)
                return -EINVAL;

        if (index >= ops->n_per_lp)
                return -EINVAL;

        if (enable != 0 && enable != 1)
                return -EINVAL;

        err = ops->perout_loopback(ops, index, enable);
        if (err)
                return err;

        return count;
}

static const struct file_operations ptp_perout_loopback_ops = {
        .owner   = THIS_MODULE,
        .open    = simple_open,
        .write   = ptp_perout_loopback_write,
};

/* public interface */

struct ptp_clock *ptp_clock_register(struct ptp_clock_info *info,
                                     struct device *parent)
{
        struct ptp_clock *ptp;
        struct timestamp_event_queue *queue = NULL;
        int err, index, major = MAJOR(ptp_devt);
        char debugfsname[16];
        size_t size;

        if (WARN_ON_ONCE(info->n_alarm > PTP_MAX_ALARMS ||
                         (!info->gettimex64 && !info->gettime64) ||
                         !info->settime64))
                return ERR_PTR(-EINVAL);

        /* Initialize a clock structure. */
        ptp = kzalloc_obj(struct ptp_clock);
        if (!ptp) {
                err = -ENOMEM;
                goto no_memory;
        }

        err = xa_alloc(&ptp_clocks_map, &index, ptp, xa_limit_31b,
                       GFP_KERNEL);
        if (err)
                goto no_slot;

        ptp->clock.ops = ptp_clock_ops;
        ptp->info = info;
        ptp->devid = MKDEV(major, index);
        ptp->index = index;
        INIT_LIST_HEAD(&ptp->tsevqs);
        queue = kzalloc_obj(*queue);
        if (!queue) {
                err = -ENOMEM;
                goto no_memory_queue;
        }
        list_add_tail(&queue->qlist, &ptp->tsevqs);
        spin_lock_init(&ptp->tsevqs_lock);
        queue->mask = bitmap_alloc(PTP_MAX_CHANNELS, GFP_KERNEL);
        if (!queue->mask) {
                err = -ENOMEM;
                goto no_memory_bitmap;
        }
        bitmap_set(queue->mask, 0, PTP_MAX_CHANNELS);
        spin_lock_init(&queue->lock);
        mutex_init(&ptp->pincfg_mux);
        mutex_init(&ptp->n_vclocks_mux);
        init_waitqueue_head(&ptp->tsev_wq);

        if (ptp->info->getcycles64 || ptp->info->getcyclesx64) {
                ptp->has_cycles = true;
                if (!ptp->info->getcycles64 && ptp->info->getcyclesx64)
                        ptp->info->getcycles64 = ptp_getcycles64;
        } else {
                /* Free running cycle counter not supported, use time. */
                ptp->info->getcycles64 = ptp_getcycles64;

                if (ptp->info->gettimex64)
                        ptp->info->getcyclesx64 = ptp->info->gettimex64;

                if (ptp->info->getcrosststamp)
                        ptp->info->getcrosscycles = ptp->info->getcrosststamp;
        }

        if (!ptp->info->enable)
                ptp->info->enable = ptp_enable;

        if (ptp->info->do_aux_work) {
                kthread_init_delayed_work(&ptp->aux_work, ptp_aux_kworker);
                ptp->kworker = kthread_run_worker(0, "ptp%d", ptp->index);
                if (IS_ERR(ptp->kworker)) {
                        err = PTR_ERR(ptp->kworker);
                        pr_err("failed to create ptp aux_worker %d\n", err);
                        goto kworker_err;
                }
        }

        /* PTP virtual clock is being registered under physical clock */
        if (parent && parent->class && parent->class->name &&
            strcmp(parent->class->name, "ptp") == 0)
                ptp->is_virtual_clock = true;

        if (!ptp->is_virtual_clock) {
                ptp->max_vclocks = PTP_DEFAULT_MAX_VCLOCKS;

                size = sizeof(int) * ptp->max_vclocks;
                ptp->vclock_index = kzalloc(size, GFP_KERNEL);
                if (!ptp->vclock_index) {
                        err = -ENOMEM;
                        goto no_mem_for_vclocks;
                }
        }

        err = ptp_populate_pin_groups(ptp);
        if (err)
                goto no_pin_groups;

        /* Register a new PPS source. */
        if (info->pps) {
                struct pps_source_info pps;
                memset(&pps, 0, sizeof(pps));
                snprintf(pps.name, PPS_MAX_NAME_LEN, "ptp%d", index);
                pps.mode = PTP_PPS_MODE;
                pps.owner = info->owner;
                ptp->pps_source = pps_register_source(&pps, PTP_PPS_DEFAULTS);
                if (IS_ERR(ptp->pps_source)) {
                        err = PTR_ERR(ptp->pps_source);
                        pr_err("failed to register pps source\n");
                        goto no_pps;
                }
                ptp->pps_source->lookup_cookie = ptp;
        }

        /* Initialize a new device of our class in our clock structure. */
        device_initialize(&ptp->dev);
        ptp->dev.devt = ptp->devid;
        ptp->dev.class = &ptp_class;
        ptp->dev.parent = parent;
        ptp->dev.groups = ptp->pin_attr_groups;
        ptp->dev.release = ptp_clock_release;
        dev_set_drvdata(&ptp->dev, ptp);
        dev_set_name(&ptp->dev, "ptp%d", ptp->index);

        /* Create a posix clock and link it to the device. */
        err = posix_clock_register(&ptp->clock, &ptp->dev);
        if (err) {
                if (ptp->pps_source)
                        pps_unregister_source(ptp->pps_source);

                if (ptp->kworker)
                        kthread_destroy_worker(ptp->kworker);

                put_device(&ptp->dev);

                pr_err("failed to create posix clock\n");
                return ERR_PTR(err);
        }

        /* Debugfs initialization */
        snprintf(debugfsname, sizeof(debugfsname), "ptp%d", ptp->index);
        ptp->debugfs_root = debugfs_create_dir(debugfsname, NULL);
        if (info->n_per_lp > 0 && info->perout_loopback) {
                debugfs_create_file("n_perout_loopback", 0400, ptp->debugfs_root,
                                    ptp, &ptp_n_perout_loopback_fops);
                debugfs_create_file("perout_loopback", 0200, ptp->debugfs_root,
                                    ptp, &ptp_perout_loopback_ops);
        }

        return ptp;

no_pps:
        ptp_cleanup_pin_groups(ptp);
no_pin_groups:
        kfree(ptp->vclock_index);
no_mem_for_vclocks:
        if (ptp->kworker)
                kthread_destroy_worker(ptp->kworker);
kworker_err:
        mutex_destroy(&ptp->pincfg_mux);
        mutex_destroy(&ptp->n_vclocks_mux);
        bitmap_free(queue->mask);
no_memory_bitmap:
        list_del(&queue->qlist);
        kfree(queue);
no_memory_queue:
        xa_erase(&ptp_clocks_map, index);
no_slot:
        kfree(ptp);
no_memory:
        return ERR_PTR(err);
}
EXPORT_SYMBOL(ptp_clock_register);

static int unregister_vclock(struct device *dev, void *data)
{
        struct ptp_clock *ptp = dev_get_drvdata(dev);

        ptp_vclock_unregister(info_to_vclock(ptp->info));
        return 0;
}

int ptp_clock_unregister(struct ptp_clock *ptp)
{
        if (ptp_vclock_in_use(ptp)) {
                device_for_each_child(&ptp->dev, NULL, unregister_vclock);
        }

        /* Get the device to stop posix_clock_unregister() doing the last put
         * and freeing the structure(s)
         */
        get_device(&ptp->dev);

        /* Wake up any userspace waiting for an event. */
        ptp->defunct = 1;
        wake_up_interruptible(&ptp->tsev_wq);

        /* Tear down the POSIX clock, which removes the user interface. */
        posix_clock_unregister(&ptp->clock);

        /* Disable all sources of event generation. */
        ptp_disable_all_events(ptp);

        if (ptp->kworker) {
                kthread_cancel_delayed_work_sync(&ptp->aux_work);
                kthread_destroy_worker(ptp->kworker);
        }

        /* Release the clock's resources. */
        if (ptp->pps_source)
                pps_unregister_source(ptp->pps_source);

        /* The final put, normally here, will invoke ptp_clock_release(). */
        put_device(&ptp->dev);

        return 0;
}
EXPORT_SYMBOL(ptp_clock_unregister);

void ptp_clock_event(struct ptp_clock *ptp, struct ptp_clock_event *event)
{
        struct timestamp_event_queue *tsevq;
        struct pps_event_time evt;
        unsigned long flags;

        switch (event->type) {

        case PTP_CLOCK_ALARM:
                break;

        case PTP_CLOCK_EXTTS:
        case PTP_CLOCK_EXTOFF:
                /* Enqueue timestamp on selected queues */
                spin_lock_irqsave(&ptp->tsevqs_lock, flags);
                list_for_each_entry(tsevq, &ptp->tsevqs, qlist) {
                        if (test_bit((unsigned int)event->index, tsevq->mask))
                                enqueue_external_timestamp(tsevq, event);
                }
                spin_unlock_irqrestore(&ptp->tsevqs_lock, flags);
                wake_up_interruptible(&ptp->tsev_wq);
                break;

        case PTP_CLOCK_PPS:
                pps_get_ts(&evt);
                pps_event(ptp->pps_source, &evt, PTP_PPS_EVENT, NULL);
                break;

        case PTP_CLOCK_PPSUSR:
                pps_event(ptp->pps_source, &event->pps_times,
                          PTP_PPS_EVENT, NULL);
                break;
        }
}
EXPORT_SYMBOL(ptp_clock_event);

int ptp_clock_index(struct ptp_clock *ptp)
{
        return ptp->index;
}
EXPORT_SYMBOL(ptp_clock_index);

static int ptp_clock_of_node_match(struct device *dev, const void *data)
{
        const struct device_node *parent_np = data;

        return (dev->parent && dev_of_node(dev->parent) == parent_np);
}

int ptp_clock_index_by_of_node(struct device_node *np)
{
        struct ptp_clock *ptp;
        struct device *dev;
        int phc_index;

        dev = class_find_device(&ptp_class, NULL, np,
                                ptp_clock_of_node_match);
        if (!dev)
                return -1;

        ptp = dev_get_drvdata(dev);
        phc_index = ptp_clock_index(ptp);
        put_device(dev);

        return phc_index;
}
EXPORT_SYMBOL_GPL(ptp_clock_index_by_of_node);

static int ptp_clock_dev_match(struct device *dev, const void *data)
{
        const struct device *parent = data;

        return dev->parent == parent;
}

int ptp_clock_index_by_dev(struct device *parent)
{
        struct ptp_clock *ptp;
        struct device *dev;
        int phc_index;

        dev = class_find_device(&ptp_class, NULL, parent,
                                ptp_clock_dev_match);
        if (!dev)
                return -1;

        ptp = dev_get_drvdata(dev);
        phc_index = ptp_clock_index(ptp);
        put_device(dev);

        return phc_index;
}
EXPORT_SYMBOL_GPL(ptp_clock_index_by_dev);

int ptp_find_pin(struct ptp_clock *ptp,
                 enum ptp_pin_function func, unsigned int chan)
{
        struct ptp_pin_desc *pin = NULL;
        int i;

        for (i = 0; i < ptp->info->n_pins; i++) {
                if (ptp->info->pin_config[i].func == func &&
                    ptp->info->pin_config[i].chan == chan) {
                        pin = &ptp->info->pin_config[i];
                        break;
                }
        }

        return pin ? i : -1;
}
EXPORT_SYMBOL(ptp_find_pin);

int ptp_find_pin_unlocked(struct ptp_clock *ptp,
                          enum ptp_pin_function func, unsigned int chan)
{
        int result;

        mutex_lock(&ptp->pincfg_mux);

        result = ptp_find_pin(ptp, func, chan);

        mutex_unlock(&ptp->pincfg_mux);

        return result;
}
EXPORT_SYMBOL(ptp_find_pin_unlocked);

int ptp_schedule_worker(struct ptp_clock *ptp, unsigned long delay)
{
        return kthread_mod_delayed_work(ptp->kworker, &ptp->aux_work, delay);
}
EXPORT_SYMBOL(ptp_schedule_worker);

void ptp_cancel_worker_sync(struct ptp_clock *ptp)
{
        kthread_cancel_delayed_work_sync(&ptp->aux_work);
}
EXPORT_SYMBOL(ptp_cancel_worker_sync);

/* module operations */

static void __exit ptp_exit(void)
{
        class_unregister(&ptp_class);
        unregister_chrdev_region(ptp_devt, MINORMASK + 1);
        xa_destroy(&ptp_clocks_map);
}

static int __init ptp_init(void)
{
        int err;

        err = class_register(&ptp_class);
        if (err) {
                pr_err("ptp: failed to allocate class\n");
                return err;
        }

        err = alloc_chrdev_region(&ptp_devt, 0, MINORMASK + 1, "ptp");
        if (err < 0) {
                pr_err("ptp: failed to allocate device region\n");
                goto no_region;
        }

        pr_info("PTP clock support registered\n");
        return 0;

no_region:
        class_unregister(&ptp_class);
        return err;
}

subsys_initcall(ptp_init);
module_exit(ptp_exit);

MODULE_AUTHOR("Richard Cochran <richardcochran@gmail.com>");
MODULE_DESCRIPTION("PTP clocks support");
MODULE_LICENSE("GPL");