ff-hwdep.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * ff-hwdep.c - a part of driver for RME Fireface series
  4 *
  5 * Copyright (c) 2015-2017 Takashi Sakamoto
  6 */
  7
  8/*
  9 * This codes give three functionality.
 10 *
 11 * 1.get firewire node information
 12 * 2.get notification about starting/stopping stream
 13 * 3.lock/unlock stream
 14 */
 15
 16#include "ff.h"
 17
 18static bool has_msg(struct snd_ff *ff)
 19{
 20	if (ff->spec->protocol->has_msg)
 21		return ff->spec->protocol->has_msg(ff);
 22	else
 23		return 0;
 24}
 25
 26static long hwdep_read(struct snd_hwdep *hwdep, char __user *buf,  long count,
 27		       loff_t *offset)
 28{
 29	struct snd_ff *ff = hwdep->private_data;
 30	DEFINE_WAIT(wait);
 31
 32	spin_lock_irq(&ff->lock);
 33
 34	while (!ff->dev_lock_changed && !has_msg(ff)) {
 35		prepare_to_wait(&ff->hwdep_wait, &wait, TASK_INTERRUPTIBLE);
 36		spin_unlock_irq(&ff->lock);
 37		schedule();
 38		finish_wait(&ff->hwdep_wait, &wait);
 39		if (signal_pending(current))
 40			return -ERESTARTSYS;
 41		spin_lock_irq(&ff->lock);
 42	}
 43
 44	if (ff->dev_lock_changed && count >= sizeof(struct snd_firewire_event_lock_status)) {
 45		struct snd_firewire_event_lock_status ev = {
 46			.type = SNDRV_FIREWIRE_EVENT_LOCK_STATUS,
 47			.status = (ff->dev_lock_count > 0),
 48		};
 49
 50		ff->dev_lock_changed = false;
 51
 52		spin_unlock_irq(&ff->lock);
 53
 54		if (copy_to_user(buf, &ev, sizeof(ev)))
 55			return -EFAULT;
 56		count = sizeof(ev);
 57	} else if (has_msg(ff)) {
 58		// NOTE: Acquired spin lock should be released before accessing to user space in the
 59		// callback since the access can cause page fault.
 60		count = ff->spec->protocol->copy_msg_to_user(ff, buf, count);
 61		spin_unlock_irq(&ff->lock);
 62	} else {
 63		spin_unlock_irq(&ff->lock);
 64
 65		count = 0;
 66	}
 67
 68	return count;
 69}
 70
 71static __poll_t hwdep_poll(struct snd_hwdep *hwdep, struct file *file,
 72			       poll_table *wait)
 73{
 74	struct snd_ff *ff = hwdep->private_data;
 75
 76	poll_wait(file, &ff->hwdep_wait, wait);
 77
 78	guard(spinlock_irq)(&ff->lock);
 79	if (ff->dev_lock_changed || has_msg(ff))
 80		return EPOLLIN | EPOLLRDNORM;
 81	else
 82		return 0;
 83}
 84
 85static int hwdep_get_info(struct snd_ff *ff, void __user *arg)
 86{
 87	struct fw_device *dev = fw_parent_device(ff->unit);
 88	struct snd_firewire_get_info info;
 89
 90	memset(&info, 0, sizeof(info));
 91	info.type = SNDRV_FIREWIRE_TYPE_FIREFACE;
 92	info.card = dev->card->index;
 93	*(__be32 *)&info.guid[0] = cpu_to_be32(dev->config_rom[3]);
 94	*(__be32 *)&info.guid[4] = cpu_to_be32(dev->config_rom[4]);
 95	strscpy(info.device_name, dev_name(&dev->device),
 96		sizeof(info.device_name));
 97
 98	if (copy_to_user(arg, &info, sizeof(info)))
 99		return -EFAULT;
100
101	return 0;
102}
103
104static int hwdep_lock(struct snd_ff *ff)
105{
106	guard(spinlock_irq)(&ff->lock);
107
108	if (ff->dev_lock_count == 0) {
109		ff->dev_lock_count = -1;
110		return 0;
111	} else {
112		return -EBUSY;
113	}
114}
115
116static int hwdep_unlock(struct snd_ff *ff)
117{
118	guard(spinlock_irq)(&ff->lock);
119
120	if (ff->dev_lock_count == -1) {
121		ff->dev_lock_count = 0;
122		return 0;
123	} else {
124		return -EBADFD;
125	}
126}
127
128static int hwdep_release(struct snd_hwdep *hwdep, struct file *file)
129{
130	struct snd_ff *ff = hwdep->private_data;
131
132	guard(spinlock_irq)(&ff->lock);
133	if (ff->dev_lock_count == -1)
134		ff->dev_lock_count = 0;
135
136	return 0;
137}
138
139static int hwdep_ioctl(struct snd_hwdep *hwdep, struct file *file,
140		       unsigned int cmd, unsigned long arg)
141{
142	struct snd_ff *ff = hwdep->private_data;
143
144	switch (cmd) {
145	case SNDRV_FIREWIRE_IOCTL_GET_INFO:
146		return hwdep_get_info(ff, (void __user *)arg);
147	case SNDRV_FIREWIRE_IOCTL_LOCK:
148		return hwdep_lock(ff);
149	case SNDRV_FIREWIRE_IOCTL_UNLOCK:
150		return hwdep_unlock(ff);
151	default:
152		return -ENOIOCTLCMD;
153	}
154}
155
156#ifdef CONFIG_COMPAT
157static int hwdep_compat_ioctl(struct snd_hwdep *hwdep, struct file *file,
158			      unsigned int cmd, unsigned long arg)
159{
160	return hwdep_ioctl(hwdep, file, cmd,
161			   (unsigned long)compat_ptr(arg));
162}
163#else
164#define hwdep_compat_ioctl NULL
165#endif
166
167int snd_ff_create_hwdep_devices(struct snd_ff *ff)
168{
169	static const struct snd_hwdep_ops hwdep_ops = {
170		.read		= hwdep_read,
171		.release	= hwdep_release,
172		.poll		= hwdep_poll,
173		.ioctl		= hwdep_ioctl,
174		.ioctl_compat	= hwdep_compat_ioctl,
175	};
176	struct snd_hwdep *hwdep;
177	int err;
178
179	err = snd_hwdep_new(ff->card, ff->card->driver, 0, &hwdep);
180	if (err < 0)
181		return err;
182
183	strscpy(hwdep->name, ff->card->driver);
184	hwdep->iface = SNDRV_HWDEP_IFACE_FW_FIREFACE;
185	hwdep->ops = hwdep_ops;
186	hwdep->private_data = ff;
187	hwdep->exclusive = true;
188
189	return 0;
190}