sound/firewire/tascam/tascam-hwdep.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * tascam-hwdep.c - a part of driver for TASCAM FireWire series
   4  *
   5  * Copyright (c) 2015 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 "tascam.h"
  17
  18 static long tscm_hwdep_read_locked(struct snd_tscm *tscm, char __user *buf,
  19                                    long count, loff_t *offset)
  20         __releases(&tscm->lock)
  21 {
  22         struct snd_firewire_event_lock_status event = {
  23                 .type = SNDRV_FIREWIRE_EVENT_LOCK_STATUS,
  24         };
  25
  26         event.status = (tscm->dev_lock_count > 0);
  27         tscm->dev_lock_changed = false;
  28         count = min_t(long, count, sizeof(event));
  29
  30         spin_unlock_irq(&tscm->lock);
  31
  32         if (copy_to_user(buf, &event, count))
  33                 return -EFAULT;
  34
  35         return count;
  36 }
  37
  38 static long tscm_hwdep_read_queue(struct snd_tscm *tscm, char __user *buf,
  39                                   long remained, loff_t *offset)
  40         __releases(&tscm->lock)
  41 {
  42         char __user *pos = buf;
  43         unsigned int type = SNDRV_FIREWIRE_EVENT_TASCAM_CONTROL;
  44         struct snd_firewire_tascam_change *entries = tscm->queue;
  45         long count;
  46
  47         // At least, one control event can be copied.
  48         if (remained < sizeof(type) + sizeof(*entries)) {
  49                 spin_unlock_irq(&tscm->lock);
  50                 return -EINVAL;
  51         }
  52
  53         // Copy the type field later.
  54         count = sizeof(type);
  55         remained -= sizeof(type);
  56         pos += sizeof(type);
  57
  58         while (true) {
  59                 unsigned int head_pos;
  60                 unsigned int tail_pos;
  61                 unsigned int length;
  62
  63                 if (tscm->pull_pos == tscm->push_pos)
  64                         break;
  65                 else if (tscm->pull_pos < tscm->push_pos)
  66                         tail_pos = tscm->push_pos;
  67                 else
  68                         tail_pos = SND_TSCM_QUEUE_COUNT;
  69                 head_pos = tscm->pull_pos;
  70
  71                 length = (tail_pos - head_pos) * sizeof(*entries);
  72                 if (remained < length)
  73                         length = rounddown(remained, sizeof(*entries));
  74                 if (length == 0)
  75                         break;
  76
  77                 spin_unlock_irq(&tscm->lock);
  78                 if (copy_to_user(pos, &entries[head_pos], length))
  79                         return -EFAULT;
  80
  81                 spin_lock_irq(&tscm->lock);
  82
  83                 tscm->pull_pos = tail_pos % SND_TSCM_QUEUE_COUNT;
  84
  85                 count += length;
  86                 remained -= length;
  87                 pos += length;
  88         }
  89
  90         spin_unlock_irq(&tscm->lock);
  91
  92         if (copy_to_user(buf, &type, sizeof(type)))
  93                 return -EFAULT;
  94
  95         return count;
  96 }
  97
  98 static long hwdep_read(struct snd_hwdep *hwdep, char __user *buf, long count,
  99                        loff_t *offset)
 100 {
 101         struct snd_tscm *tscm = hwdep->private_data;
 102         DEFINE_WAIT(wait);
 103
 104         spin_lock_irq(&tscm->lock);
 105
 106         while (!tscm->dev_lock_changed && tscm->push_pos == tscm->pull_pos) {
 107                 prepare_to_wait(&tscm->hwdep_wait, &wait, TASK_INTERRUPTIBLE);
 108                 spin_unlock_irq(&tscm->lock);
 109                 schedule();
 110                 finish_wait(&tscm->hwdep_wait, &wait);
 111                 if (signal_pending(current))
 112                         return -ERESTARTSYS;
 113                 spin_lock_irq(&tscm->lock);
 114         }
 115
 116         // NOTE: The acquired lock should be released in callee side.
 117         if (tscm->dev_lock_changed) {
 118                 count = tscm_hwdep_read_locked(tscm, buf, count, offset);
 119         } else if (tscm->push_pos != tscm->pull_pos) {
 120                 count = tscm_hwdep_read_queue(tscm, buf, count, offset);
 121         } else {
 122                 spin_unlock_irq(&tscm->lock);
 123                 count = 0;
 124         }
 125
 126         return count;
 127 }
 128
 129 static __poll_t hwdep_poll(struct snd_hwdep *hwdep, struct file *file,
 130                                poll_table *wait)
 131 {
 132         struct snd_tscm *tscm = hwdep->private_data;
 133         __poll_t events;
 134
 135         poll_wait(file, &tscm->hwdep_wait, wait);
 136
 137         spin_lock_irq(&tscm->lock);
 138         if (tscm->dev_lock_changed || tscm->push_pos != tscm->pull_pos)
 139                 events = EPOLLIN | EPOLLRDNORM;
 140         else
 141                 events = 0;
 142         spin_unlock_irq(&tscm->lock);
 143
 144         return events;
 145 }
 146
 147 static int hwdep_get_info(struct snd_tscm *tscm, void __user *arg)
 148 {
 149         struct fw_device *dev = fw_parent_device(tscm->unit);
 150         struct snd_firewire_get_info info;
 151
 152         memset(&info, 0, sizeof(info));
 153         info.type = SNDRV_FIREWIRE_TYPE_TASCAM;
 154         info.card = dev->card->index;
 155         *(__be32 *)&info.guid[0] = cpu_to_be32(dev->config_rom[3]);
 156         *(__be32 *)&info.guid[4] = cpu_to_be32(dev->config_rom[4]);
 157         strlcpy(info.device_name, dev_name(&dev->device),
 158                 sizeof(info.device_name));
 159
 160         if (copy_to_user(arg, &info, sizeof(info)))
 161                 return -EFAULT;
 162
 163         return 0;
 164 }
 165
 166 static int hwdep_lock(struct snd_tscm *tscm)
 167 {
 168         int err;
 169
 170         spin_lock_irq(&tscm->lock);
 171
 172         if (tscm->dev_lock_count == 0) {
 173                 tscm->dev_lock_count = -1;
 174                 err = 0;
 175         } else {
 176                 err = -EBUSY;
 177         }
 178
 179         spin_unlock_irq(&tscm->lock);
 180
 181         return err;
 182 }
 183
 184 static int hwdep_unlock(struct snd_tscm *tscm)
 185 {
 186         int err;
 187
 188         spin_lock_irq(&tscm->lock);
 189
 190         if (tscm->dev_lock_count == -1) {
 191                 tscm->dev_lock_count = 0;
 192                 err = 0;
 193         } else {
 194                 err = -EBADFD;
 195         }
 196
 197         spin_unlock_irq(&tscm->lock);
 198
 199         return err;
 200 }
 201
 202 static int tscm_hwdep_state(struct snd_tscm *tscm, void __user *arg)
 203 {
 204         if (copy_to_user(arg, tscm->state, sizeof(tscm->state)))
 205                 return -EFAULT;
 206
 207         return 0;
 208 }
 209
 210 static int hwdep_release(struct snd_hwdep *hwdep, struct file *file)
 211 {
 212         struct snd_tscm *tscm = hwdep->private_data;
 213
 214         spin_lock_irq(&tscm->lock);
 215         if (tscm->dev_lock_count == -1)
 216                 tscm->dev_lock_count = 0;
 217         spin_unlock_irq(&tscm->lock);
 218
 219         return 0;
 220 }
 221
 222 static int hwdep_ioctl(struct snd_hwdep *hwdep, struct file *file,
 223             unsigned int cmd, unsigned long arg)
 224 {
 225         struct snd_tscm *tscm = hwdep->private_data;
 226
 227         switch (cmd) {
 228         case SNDRV_FIREWIRE_IOCTL_GET_INFO:
 229                 return hwdep_get_info(tscm, (void __user *)arg);
 230         case SNDRV_FIREWIRE_IOCTL_LOCK:
 231                 return hwdep_lock(tscm);
 232         case SNDRV_FIREWIRE_IOCTL_UNLOCK:
 233                 return hwdep_unlock(tscm);
 234         case SNDRV_FIREWIRE_IOCTL_TASCAM_STATE:
 235                 return tscm_hwdep_state(tscm, (void __user *)arg);
 236         default:
 237                 return -ENOIOCTLCMD;
 238         }
 239 }
 240
 241 #ifdef CONFIG_COMPAT
 242 static int hwdep_compat_ioctl(struct snd_hwdep *hwdep, struct file *file,
 243                               unsigned int cmd, unsigned long arg)
 244 {
 245         return hwdep_ioctl(hwdep, file, cmd,
 246                            (unsigned long)compat_ptr(arg));
 247 }
 248 #else
 249 #define hwdep_compat_ioctl NULL
 250 #endif
 251
 252 int snd_tscm_create_hwdep_device(struct snd_tscm *tscm)
 253 {
 254         static const struct snd_hwdep_ops ops = {
 255                 .read           = hwdep_read,
 256                 .release        = hwdep_release,
 257                 .poll           = hwdep_poll,
 258                 .ioctl          = hwdep_ioctl,
 259                 .ioctl_compat   = hwdep_compat_ioctl,
 260         };
 261         struct snd_hwdep *hwdep;
 262         int err;
 263
 264         err = snd_hwdep_new(tscm->card, "Tascam", 0, &hwdep);
 265         if (err < 0)
 266                 return err;
 267
 268         strcpy(hwdep->name, "Tascam");
 269         hwdep->iface = SNDRV_HWDEP_IFACE_FW_TASCAM;
 270         hwdep->ops = ops;
 271         hwdep->private_data = tscm;
 272         hwdep->exclusive = true;
 273
 274         tscm->hwdep = hwdep;
 275
 276         return err;
 277 }