text: // 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 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);
  	union snd_firewire_event event;
  
  	spin_lock_irq(&ff->lock);
  
  	while (!ff->dev_lock_changed) {
  		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);
  	}
  
  	memset(&event, 0, sizeof(event));
  	if (ff->dev_lock_changed) {
  		event.lock_status.type = SNDRV_FIREWIRE_EVENT_LOCK_STATUS;
  		event.lock_status.status = (ff->dev_lock_count > 0);
  		ff->dev_lock_changed = false;
  
  		count = min_t(long, count, sizeof(event.lock_status));
  	}
  
  	spin_unlock_irq(&ff->lock);
  
  	if (copy_to_user(buf, &event, count))
  		return -EFAULT;
  
  	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_t events;
  
  	poll_wait(file, &ff->hwdep_wait, wait);
  
  	spin_lock_irq(&ff->lock);
  	if (ff->dev_lock_changed)
  		events = EPOLLIN | EPOLLRDNORM;
  	else
  		events = 0;
  	spin_unlock_irq(&ff->lock);
  
  	return events;
  }
  
  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]);
  	strlcpy(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)
  {
  	int err;
  
  	spin_lock_irq(&ff->lock);
  
  	if (ff->dev_lock_count == 0) {
  		ff->dev_lock_count = -1;
  		err = 0;
  	} else {
  		err = -EBUSY;
  	}
  
  	spin_unlock_irq(&ff->lock);
  
  	return err;
  }
  
  static int hwdep_unlock(struct snd_ff *ff)
  {
  	int err;
  
  	spin_lock_irq(&ff->lock);
  
  	if (ff->dev_lock_count == -1) {
  		ff->dev_lock_count = 0;
  		err = 0;
  	} else {
  		err = -EBADFD;
  	}
  
  	spin_unlock_irq(&ff->lock);
  
  	return err;
  }
  
  static int hwdep_release(struct snd_hwdep *hwdep, struct file *file)
  {
  	struct snd_ff *ff = hwdep->private_data;
  
  	spin_lock_irq(&ff->lock);
  	if (ff->dev_lock_count == -1)
  		ff->dev_lock_count = 0;
  	spin_unlock_irq(&ff->lock);
  
  	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;
  
  	strcpy(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;
  }
  