// SPDX-License-Identifier: GPL-2.0-only
/*
 * ff-hwdep.c - a part of driver for RME Fireface series
 *
 * Copyright (c) 2015-2017 Takashi Sakamoto
 */

/*
 * This codes give three functionality.
 *
 * 1.get firewire node information
 * 2.get notification about starting/stopping stream
 * 3.lock/unlock stream
 */

#include "ff.h"

static bool has_msg(struct snd_ff *ff)
{
        if (ff->spec->protocol->has_msg)
                return ff->spec->protocol->has_msg(ff);
        else
                return 0;
}

static long hwdep_read(struct snd_hwdep *hwdep, char __user *buf,  long count,
                       loff_t *offset)
{
        struct snd_ff *ff = hwdep->private_data;
        DEFINE_WAIT(wait);

        spin_lock_irq(&ff->lock);

        while (!ff->dev_lock_changed && !has_msg(ff)) {
                prepare_to_wait(&ff->hwdep_wait, &wait, TASK_INTERRUPTIBLE);
                spin_unlock_irq(&ff->lock);
                schedule();
                finish_wait(&ff->hwdep_wait, &wait);
                if (signal_pending(current))
                        return -ERESTARTSYS;
                spin_lock_irq(&ff->lock);
        }

        if (ff->dev_lock_changed && count >= sizeof(struct snd_firewire_event_lock_status)) {
                struct snd_firewire_event_lock_status ev = {
                        .type = SNDRV_FIREWIRE_EVENT_LOCK_STATUS,
                        .status = (ff->dev_lock_count > 0),
                };

                ff->dev_lock_changed = false;

                spin_unlock_irq(&ff->lock);

                if (copy_to_user(buf, &ev, sizeof(ev)))
                        return -EFAULT;
                count = sizeof(ev);
        } else if (has_msg(ff)) {
                // NOTE: Acquired spin lock should be released before accessing to user space in the
                // callback since the access can cause page fault.
                count = ff->spec->protocol->copy_msg_to_user(ff, buf, count);
                spin_unlock_irq(&ff->lock);
        } else {
                spin_unlock_irq(&ff->lock);

                count = 0;
        }

        return count;
}

static __poll_t hwdep_poll(struct snd_hwdep *hwdep, struct file *file,
                               poll_table *wait)
{
        struct snd_ff *ff = hwdep->private_data;

        poll_wait(file, &ff->hwdep_wait, wait);

        guard(spinlock_irq)(&ff->lock);
        if (ff->dev_lock_changed || has_msg(ff))
                return EPOLLIN | EPOLLRDNORM;
        else
                return 0;
}

static int hwdep_get_info(struct snd_ff *ff, void __user *arg)
{
        struct fw_device *dev = fw_parent_device(ff->unit);
        struct snd_firewire_get_info info;

        memset(&info, 0, sizeof(info));
        info.type = SNDRV_FIREWIRE_TYPE_FIREFACE;
        info.card = dev->card->index;
        *(__be32 *)&info.guid[0] = cpu_to_be32(dev->config_rom[3]);
        *(__be32 *)&info.guid[4] = cpu_to_be32(dev->config_rom[4]);
        strscpy(info.device_name, dev_name(&dev->device),
                sizeof(info.device_name));

        if (copy_to_user(arg, &info, sizeof(info)))
                return -EFAULT;

        return 0;
}

static int hwdep_lock(struct snd_ff *ff)
{
        guard(spinlock_irq)(&ff->lock);

        if (ff->dev_lock_count == 0) {
                ff->dev_lock_count = -1;
                return 0;
        } else {
                return -EBUSY;
        }
}

static int hwdep_unlock(struct snd_ff *ff)
{
        guard(spinlock_irq)(&ff->lock);

        if (ff->dev_lock_count == -1) {
                ff->dev_lock_count = 0;
                return 0;
        } else {
                return -EBADFD;
        }
}

static int hwdep_release(struct snd_hwdep *hwdep, struct file *file)
{
        struct snd_ff *ff = hwdep->private_data;

        guard(spinlock_irq)(&ff->lock);
        if (ff->dev_lock_count == -1)
                ff->dev_lock_count = 0;

        return 0;
}

static int hwdep_ioctl(struct snd_hwdep *hwdep, struct file *file,
                       unsigned int cmd, unsigned long arg)
{
        struct snd_ff *ff = hwdep->private_data;

        switch (cmd) {
        case SNDRV_FIREWIRE_IOCTL_GET_INFO:
                return hwdep_get_info(ff, (void __user *)arg);
        case SNDRV_FIREWIRE_IOCTL_LOCK:
                return hwdep_lock(ff);
        case SNDRV_FIREWIRE_IOCTL_UNLOCK:
                return hwdep_unlock(ff);
        default:
                return -ENOIOCTLCMD;
        }
}

#ifdef CONFIG_COMPAT
static int hwdep_compat_ioctl(struct snd_hwdep *hwdep, struct file *file,
                              unsigned int cmd, unsigned long arg)
{
        return hwdep_ioctl(hwdep, file, cmd,
                           (unsigned long)compat_ptr(arg));
}
#else
#define hwdep_compat_ioctl NULL
#endif

int snd_ff_create_hwdep_devices(struct snd_ff *ff)
{
        static const struct snd_hwdep_ops hwdep_ops = {
                .read           = hwdep_read,
                .release        = hwdep_release,
                .poll           = hwdep_poll,
                .ioctl          = hwdep_ioctl,
                .ioctl_compat   = hwdep_compat_ioctl,
        };
        struct snd_hwdep *hwdep;
        int err;

        err = snd_hwdep_new(ff->card, ff->card->driver, 0, &hwdep);
        if (err < 0)
                return err;

        strscpy(hwdep->name, ff->card->driver);
        hwdep->iface = SNDRV_HWDEP_IFACE_FW_FIREFACE;
        hwdep->ops = hwdep_ops;
        hwdep->private_data = ff;
        hwdep->exclusive = true;

        return 0;
}