root/sound/firewire/motu/motu-hwdep.c
// SPDX-License-Identifier: GPL-2.0-only
/*
 * motu-hwdep.c - a part of driver for MOTU FireWire series
 *
 * Copyright (c) 2015-2017 Takashi Sakamoto <o-takashi@sakamocchi.jp>
 */

/*
 * This codes have five functionalities.
 *
 * 1.get information about firewire node
 * 2.get notification about starting/stopping stream
 * 3.lock/unlock streaming
 *
 */

#include "motu.h"

static bool has_dsp_event(struct snd_motu *motu)
{
        if (motu->spec->flags & SND_MOTU_SPEC_REGISTER_DSP)
                return (snd_motu_register_dsp_message_parser_count_event(motu) > 0);
        else
                return false;
}

static long hwdep_read(struct snd_hwdep *hwdep, char __user *buf, long count,
                       loff_t *offset)
{
        struct snd_motu *motu = hwdep->private_data;
        DEFINE_WAIT(wait);
        union snd_firewire_event event;

        spin_lock_irq(&motu->lock);

        while (!motu->dev_lock_changed && motu->msg == 0 && !has_dsp_event(motu)) {
                prepare_to_wait(&motu->hwdep_wait, &wait, TASK_INTERRUPTIBLE);
                spin_unlock_irq(&motu->lock);
                schedule();
                finish_wait(&motu->hwdep_wait, &wait);
                if (signal_pending(current))
                        return -ERESTARTSYS;
                spin_lock_irq(&motu->lock);
        }

        memset(&event, 0, sizeof(event));
        if (motu->dev_lock_changed) {
                event.lock_status.type = SNDRV_FIREWIRE_EVENT_LOCK_STATUS;
                event.lock_status.status = (motu->dev_lock_count > 0);
                motu->dev_lock_changed = false;
                spin_unlock_irq(&motu->lock);

                count = min_t(long, count, sizeof(event));
                if (copy_to_user(buf, &event, count))
                        return -EFAULT;
        } else if (motu->msg > 0) {
                event.motu_notification.type = SNDRV_FIREWIRE_EVENT_MOTU_NOTIFICATION;
                event.motu_notification.message = motu->msg;
                motu->msg = 0;
                spin_unlock_irq(&motu->lock);

                count = min_t(long, count, sizeof(event));
                if (copy_to_user(buf, &event, count))
                        return -EFAULT;
        } else if (has_dsp_event(motu)) {
                size_t consumed = 0;
                u32 __user *ptr;
                u32 ev;

                spin_unlock_irq(&motu->lock);

                // Header is filled later.
                consumed += sizeof(event.motu_register_dsp_change);

                while (consumed < count &&
                       snd_motu_register_dsp_message_parser_copy_event(motu, &ev)) {
                        ptr = (u32 __user *)(buf + consumed);
                        if (consumed + sizeof(ev) > count || put_user(ev, ptr))
                                return -EFAULT;
                        consumed += sizeof(ev);
                }

                event.motu_register_dsp_change.type = SNDRV_FIREWIRE_EVENT_MOTU_REGISTER_DSP_CHANGE;
                event.motu_register_dsp_change.count =
                        (consumed - sizeof(event.motu_register_dsp_change)) / 4;
                if (copy_to_user(buf, &event,
                                 min_t(long, count, sizeof(event.motu_register_dsp_change))))
                        return -EFAULT;

                count = min_t(long, count, consumed);
        } else {
                spin_unlock_irq(&motu->lock);

                count = 0;
        }

        return count;
}

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

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

        guard(spinlock_irq)(&motu->lock);
        if (motu->dev_lock_changed || motu->msg || has_dsp_event(motu))
                return EPOLLIN | EPOLLRDNORM;
        else
                return 0;
}

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

        memset(&info, 0, sizeof(info));
        info.type = SNDRV_FIREWIRE_TYPE_MOTU;
        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_motu *motu)
{
        guard(spinlock_irq)(&motu->lock);

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

static int hwdep_unlock(struct snd_motu *motu)
{
        guard(spinlock_irq)(&motu->lock);

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

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

        guard(spinlock_irq)(&motu->lock);
        if (motu->dev_lock_count == -1)
                motu->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_motu *motu = hwdep->private_data;

        switch (cmd) {
        case SNDRV_FIREWIRE_IOCTL_GET_INFO:
                return hwdep_get_info(motu, (void __user *)arg);
        case SNDRV_FIREWIRE_IOCTL_LOCK:
                return hwdep_lock(motu);
        case SNDRV_FIREWIRE_IOCTL_UNLOCK:
                return hwdep_unlock(motu);
        case SNDRV_FIREWIRE_IOCTL_MOTU_REGISTER_DSP_METER:
        {
                struct snd_firewire_motu_register_dsp_meter *meter;
                int err;

                if (!(motu->spec->flags & SND_MOTU_SPEC_REGISTER_DSP))
                        return -ENXIO;

                meter = kzalloc_obj(*meter);
                if (!meter)
                        return -ENOMEM;

                snd_motu_register_dsp_message_parser_copy_meter(motu, meter);

                err = copy_to_user((void __user *)arg, meter, sizeof(*meter));
                kfree(meter);

                if (err)
                        return -EFAULT;

                return 0;
        }
        case SNDRV_FIREWIRE_IOCTL_MOTU_COMMAND_DSP_METER:
        {
                struct snd_firewire_motu_command_dsp_meter *meter;
                int err;

                if (!(motu->spec->flags & SND_MOTU_SPEC_COMMAND_DSP))
                        return -ENXIO;

                meter = kzalloc_obj(*meter);
                if (!meter)
                        return -ENOMEM;

                snd_motu_command_dsp_message_parser_copy_meter(motu, meter);

                err = copy_to_user((void __user *)arg, meter, sizeof(*meter));
                kfree(meter);

                if (err)
                        return -EFAULT;

                return 0;
        }
        case SNDRV_FIREWIRE_IOCTL_MOTU_REGISTER_DSP_PARAMETER:
        {
                struct snd_firewire_motu_register_dsp_parameter *param;
                int err;

                if (!(motu->spec->flags & SND_MOTU_SPEC_REGISTER_DSP))
                        return -ENXIO;

                param = kzalloc_obj(*param);
                if (!param)
                        return -ENOMEM;

                snd_motu_register_dsp_message_parser_copy_parameter(motu, param);

                err = copy_to_user((void __user *)arg, param, sizeof(*param));
                kfree(param);
                if (err)
                        return -EFAULT;

                return 0;
        }
        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_motu_create_hwdep_device(struct snd_motu *motu)
{
        static const struct snd_hwdep_ops 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(motu->card, motu->card->driver, 0, &hwdep);
        if (err < 0)
                return err;

        strscpy(hwdep->name, "MOTU");
        hwdep->iface = SNDRV_HWDEP_IFACE_FW_MOTU;
        hwdep->ops = ops;
        hwdep->private_data = motu;
        hwdep->exclusive = true;

        motu->hwdep = hwdep;

        return 0;
}