fireworks_hwdep.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * fireworks_hwdep.c - a part of driver for Fireworks based devices
  4 *
  5 * Copyright (c) 2013-2014 Takashi Sakamoto
  6 */
  7
  8/*
  9 * This codes have five functionalities.
 10 *
 11 * 1.get information about firewire node
 12 * 2.get notification about starting/stopping stream
 13 * 3.lock/unlock streaming
 14 * 4.transmit command of EFW transaction
 15 * 5.receive response of EFW transaction
 16 *
 17 */
 18
 19#include "fireworks.h"
 20
 21static long
 22hwdep_read_resp_buf(struct snd_efw *efw, char __user *buf, long remained,
 23		    loff_t *offset)
 24{
 25	unsigned int length, till_end, type;
 26	struct snd_efw_transaction *t;
 27	u8 *pull_ptr;
 28	long count = 0;
 29
 30	if (remained < sizeof(type) + sizeof(struct snd_efw_transaction))
 31		return -ENOSPC;
 32
 33	/* data type is SNDRV_FIREWIRE_EVENT_EFW_RESPONSE */
 34	type = SNDRV_FIREWIRE_EVENT_EFW_RESPONSE;
 35	if (copy_to_user(buf, &type, sizeof(type)))
 36		return -EFAULT;
 37	count += sizeof(type);
 38	remained -= sizeof(type);
 39	buf += sizeof(type);
 40
 41	/* write into buffer as many responses as possible */
 42	spin_lock_irq(&efw->lock);
 43
 44	/*
 45	 * When another task reaches here during this task's access to user
 46	 * space, it picks up current position in buffer and can read the same
 47	 * series of responses.
 48	 */
 49	pull_ptr = efw->pull_ptr;
 50
 51	while (efw->push_ptr != pull_ptr) {
 52		t = (struct snd_efw_transaction *)(pull_ptr);
 53		length = be32_to_cpu(t->length) * sizeof(__be32);
 54
 55		/* confirm enough space for this response */
 56		if (remained < length)
 57			break;
 58
 59		/* copy from ring buffer to user buffer */
 60		while (length > 0) {
 61			till_end = snd_efw_resp_buf_size -
 62				(unsigned int)(pull_ptr - efw->resp_buf);
 63			till_end = min_t(unsigned int, length, till_end);
 64
 65			spin_unlock_irq(&efw->lock);
 66
 67			if (copy_to_user(buf, pull_ptr, till_end))
 68				return -EFAULT;
 69
 70			spin_lock_irq(&efw->lock);
 71
 72			pull_ptr += till_end;
 73			if (pull_ptr >= efw->resp_buf + snd_efw_resp_buf_size)
 74				pull_ptr -= snd_efw_resp_buf_size;
 75
 76			length -= till_end;
 77			buf += till_end;
 78			count += till_end;
 79			remained -= till_end;
 80		}
 81	}
 82
 83	/*
 84	 * All of tasks can read from the buffer nearly simultaneously, but the
 85	 * last position for each task is different depending on the length of
 86	 * given buffer. Here, for simplicity, a position of buffer is set by
 87	 * the latest task. It's better for a listening application to allow one
 88	 * thread to read from the buffer. Unless, each task can read different
 89	 * sequence of responses depending on variation of buffer length.
 90	 */
 91	efw->pull_ptr = pull_ptr;
 92
 93	spin_unlock_irq(&efw->lock);
 94
 95	return count;
 96}
 97
 98static long
 99hwdep_read_locked(struct snd_efw *efw, char __user *buf, long count,
100		  loff_t *offset)
101{
102	union snd_firewire_event event = {
103		.lock_status.type = SNDRV_FIREWIRE_EVENT_LOCK_STATUS,
104	};
105
106	scoped_guard(spinlock_irq, &efw->lock) {
107		event.lock_status.status = (efw->dev_lock_count > 0);
108		efw->dev_lock_changed = false;
109	}
110
111	count = min_t(long, count, sizeof(event.lock_status));
112
113	if (copy_to_user(buf, &event, count))
114		return -EFAULT;
115
116	return count;
117}
118
119static long
120hwdep_read(struct snd_hwdep *hwdep, char __user *buf, long count,
121	   loff_t *offset)
122{
123	struct snd_efw *efw = hwdep->private_data;
124	DEFINE_WAIT(wait);
125	bool dev_lock_changed;
126	bool queued;
127
128	spin_lock_irq(&efw->lock);
129
130	dev_lock_changed = efw->dev_lock_changed;
131	queued = efw->push_ptr != efw->pull_ptr;
132
133	while (!dev_lock_changed && !queued) {
134		prepare_to_wait(&efw->hwdep_wait, &wait, TASK_INTERRUPTIBLE);
135		spin_unlock_irq(&efw->lock);
136		schedule();
137		finish_wait(&efw->hwdep_wait, &wait);
138		if (signal_pending(current))
139			return -ERESTARTSYS;
140		spin_lock_irq(&efw->lock);
141		dev_lock_changed = efw->dev_lock_changed;
142		queued = efw->push_ptr != efw->pull_ptr;
143	}
144
145	spin_unlock_irq(&efw->lock);
146
147	if (dev_lock_changed)
148		count = hwdep_read_locked(efw, buf, count, offset);
149	else if (queued)
150		count = hwdep_read_resp_buf(efw, buf, count, offset);
151
152	return count;
153}
154
155static long
156hwdep_write(struct snd_hwdep *hwdep, const char __user *data, long count,
157	    loff_t *offset)
158{
159	struct snd_efw *efw = hwdep->private_data;
160	u32 seqnum;
161	u8 *buf;
162
163	if (count < sizeof(struct snd_efw_transaction) ||
164	    SND_EFW_RESPONSE_MAXIMUM_BYTES < count)
165		return -EINVAL;
166
167	buf = memdup_user(data, count);
168	if (IS_ERR(buf))
169		return PTR_ERR(buf);
170
171	/* check seqnum is not for kernel-land */
172	seqnum = be32_to_cpu(((struct snd_efw_transaction *)buf)->seqnum);
173	if (seqnum > SND_EFW_TRANSACTION_USER_SEQNUM_MAX) {
174		count = -EINVAL;
175		goto end;
176	}
177
178	if (snd_efw_transaction_cmd(efw->unit, buf, count) < 0)
179		count = -EIO;
180end:
181	kfree(buf);
182	return count;
183}
184
185static __poll_t
186hwdep_poll(struct snd_hwdep *hwdep, struct file *file, poll_table *wait)
187{
188	struct snd_efw *efw = hwdep->private_data;
189	__poll_t events;
190
191	poll_wait(file, &efw->hwdep_wait, wait);
192
193	guard(spinlock_irq)(&efw->lock);
194	if (efw->dev_lock_changed || efw->pull_ptr != efw->push_ptr)
195		events = EPOLLIN | EPOLLRDNORM;
196	else
197		events = 0;
198	return events | EPOLLOUT;
199}
200
201static int
202hwdep_get_info(struct snd_efw *efw, void __user *arg)
203{
204	struct fw_device *dev = fw_parent_device(efw->unit);
205	struct snd_firewire_get_info info;
206
207	memset(&info, 0, sizeof(info));
208	info.type = SNDRV_FIREWIRE_TYPE_FIREWORKS;
209	info.card = dev->card->index;
210	*(__be32 *)&info.guid[0] = cpu_to_be32(dev->config_rom[3]);
211	*(__be32 *)&info.guid[4] = cpu_to_be32(dev->config_rom[4]);
212	strscpy(info.device_name, dev_name(&dev->device),
213		sizeof(info.device_name));
214
215	if (copy_to_user(arg, &info, sizeof(info)))
216		return -EFAULT;
217
218	return 0;
219}
220
221static int
222hwdep_lock(struct snd_efw *efw)
223{
224	guard(spinlock_irq)(&efw->lock);
225
226	if (efw->dev_lock_count == 0) {
227		efw->dev_lock_count = -1;
228		return 0;
229	} else {
230		return -EBUSY;
231	}
232}
233
234static int
235hwdep_unlock(struct snd_efw *efw)
236{
237	guard(spinlock_irq)(&efw->lock);
238
239	if (efw->dev_lock_count == -1) {
240		efw->dev_lock_count = 0;
241		return 0;
242	} else {
243		return -EBADFD;
244	}
245}
246
247static int
248hwdep_release(struct snd_hwdep *hwdep, struct file *file)
249{
250	struct snd_efw *efw = hwdep->private_data;
251
252	guard(spinlock_irq)(&efw->lock);
253	if (efw->dev_lock_count == -1)
254		efw->dev_lock_count = 0;
255
256	return 0;
257}
258
259static int
260hwdep_ioctl(struct snd_hwdep *hwdep, struct file *file,
261	    unsigned int cmd, unsigned long arg)
262{
263	struct snd_efw *efw = hwdep->private_data;
264
265	switch (cmd) {
266	case SNDRV_FIREWIRE_IOCTL_GET_INFO:
267		return hwdep_get_info(efw, (void __user *)arg);
268	case SNDRV_FIREWIRE_IOCTL_LOCK:
269		return hwdep_lock(efw);
270	case SNDRV_FIREWIRE_IOCTL_UNLOCK:
271		return hwdep_unlock(efw);
272	default:
273		return -ENOIOCTLCMD;
274	}
275}
276
277#ifdef CONFIG_COMPAT
278static int
279hwdep_compat_ioctl(struct snd_hwdep *hwdep, struct file *file,
280		   unsigned int cmd, unsigned long arg)
281{
282	return hwdep_ioctl(hwdep, file, cmd,
283			   (unsigned long)compat_ptr(arg));
284}
285#else
286#define hwdep_compat_ioctl NULL
287#endif
288
289int snd_efw_create_hwdep_device(struct snd_efw *efw)
290{
291	static const struct snd_hwdep_ops ops = {
292		.read		= hwdep_read,
293		.write		= hwdep_write,
294		.release	= hwdep_release,
295		.poll		= hwdep_poll,
296		.ioctl		= hwdep_ioctl,
297		.ioctl_compat	= hwdep_compat_ioctl,
298	};
299	struct snd_hwdep *hwdep;
300	int err;
301
302	err = snd_hwdep_new(efw->card, "Fireworks", 0, &hwdep);
303	if (err < 0)
304		goto end;
305	strscpy(hwdep->name, "Fireworks");
306	hwdep->iface = SNDRV_HWDEP_IFACE_FW_FIREWORKS;
307	hwdep->ops = ops;
308	hwdep->private_data = efw;
309	hwdep->exclusive = true;
310end:
311	return err;
312}
313