sound/core/seq/seq_fifo.c

   1 /*
   2  *   ALSA sequencer FIFO
   3  *   Copyright (c) 1998 by Frank van de Pol <fvdpol@coil.demon.nl>
   4  *
   5  *
   6  *   This program is free software; you can redistribute it and/or modify
   7  *   it under the terms of the GNU General Public License as published by
   8  *   the Free Software Foundation; either version 2 of the License, or
   9  *   (at your option) any later version.
  10  *
  11  *   This program is distributed in the hope that it will be useful,
  12  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *   GNU General Public License for more details.
  15  *
  16  *   You should have received a copy of the GNU General Public License
  17  *   along with this program; if not, write to the Free Software
  18  *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
  19  *
  20  */
  21
  22 #include <sound/core.h>
  23 #include <linux/slab.h>
  24 #include "seq_fifo.h"
  25 #include "seq_lock.h"
  26
  27
  28 /* FIFO */
  29
  30 /* create new fifo */
  31 struct snd_seq_fifo *snd_seq_fifo_new(int poolsize)
  32 {
  33         struct snd_seq_fifo *f;
  34
  35         f = kzalloc(sizeof(*f), GFP_KERNEL);
  36         if (!f)
  37                 return NULL;
  38
  39         f->pool = snd_seq_pool_new(poolsize);
  40         if (f->pool == NULL) {
  41                 kfree(f);
  42                 return NULL;
  43         }
  44         if (snd_seq_pool_init(f->pool) < 0) {
  45                 snd_seq_pool_delete(&f->pool);
  46                 kfree(f);
  47                 return NULL;
  48         }
  49
  50         spin_lock_init(&f->lock);
  51         snd_use_lock_init(&f->use_lock);
  52         init_waitqueue_head(&f->input_sleep);
  53         atomic_set(&f->overflow, 0);
  54
  55         f->head = NULL;
  56         f->tail = NULL;
  57         f->cells = 0;
  58
  59         return f;
  60 }
  61
  62 void snd_seq_fifo_delete(struct snd_seq_fifo **fifo)
  63 {
  64         struct snd_seq_fifo *f;
  65
  66         if (snd_BUG_ON(!fifo))
  67                 return;
  68         f = *fifo;
  69         if (snd_BUG_ON(!f))
  70                 return;
  71         *fifo = NULL;
  72
  73         if (f->pool)
  74                 snd_seq_pool_mark_closing(f->pool);
  75
  76         snd_seq_fifo_clear(f);
  77
  78         /* wake up clients if any */
  79         if (waitqueue_active(&f->input_sleep))
  80                 wake_up(&f->input_sleep);
  81
  82         /* release resources...*/
  83         /*....................*/
  84
  85         if (f->pool) {
  86                 snd_seq_pool_done(f->pool);
  87                 snd_seq_pool_delete(&f->pool);
  88         }
  89
  90         kfree(f);
  91 }
  92
  93 static struct snd_seq_event_cell *fifo_cell_out(struct snd_seq_fifo *f);
  94
  95 /* clear queue */
  96 void snd_seq_fifo_clear(struct snd_seq_fifo *f)
  97 {
  98         struct snd_seq_event_cell *cell;
  99         unsigned long flags;
 100
 101         /* clear overflow flag */
 102         atomic_set(&f->overflow, 0);
 103
 104         snd_use_lock_sync(&f->use_lock);
 105         spin_lock_irqsave(&f->lock, flags);
 106         /* drain the fifo */
 107         while ((cell = fifo_cell_out(f)) != NULL) {
 108                 snd_seq_cell_free(cell);
 109         }
 110         spin_unlock_irqrestore(&f->lock, flags);
 111 }
 112
 113
 114 /* enqueue event to fifo */
 115 int snd_seq_fifo_event_in(struct snd_seq_fifo *f,
 116                           struct snd_seq_event *event)
 117 {
 118         struct snd_seq_event_cell *cell;
 119         unsigned long flags;
 120         int err;
 121
 122         if (snd_BUG_ON(!f))
 123                 return -EINVAL;
 124
 125         snd_use_lock_use(&f->use_lock);
 126         err = snd_seq_event_dup(f->pool, event, &cell, 1, NULL, NULL); /* always non-blocking */
 127         if (err < 0) {
 128                 if ((err == -ENOMEM) || (err == -EAGAIN))
 129                         atomic_inc(&f->overflow);
 130                 snd_use_lock_free(&f->use_lock);
 131                 return err;
 132         }
 133
 134         /* append new cells to fifo */
 135         spin_lock_irqsave(&f->lock, flags);
 136         if (f->tail != NULL)
 137                 f->tail->next = cell;
 138         f->tail = cell;
 139         if (f->head == NULL)
 140                 f->head = cell;
 141         cell->next = NULL;
 142         f->cells++;
 143         spin_unlock_irqrestore(&f->lock, flags);
 144
 145         /* wakeup client */
 146         if (waitqueue_active(&f->input_sleep))
 147                 wake_up(&f->input_sleep);
 148
 149         snd_use_lock_free(&f->use_lock);
 150
 151         return 0; /* success */
 152
 153 }
 154
 155 /* dequeue cell from fifo */
 156 static struct snd_seq_event_cell *fifo_cell_out(struct snd_seq_fifo *f)
 157 {
 158         struct snd_seq_event_cell *cell;
 159
 160         if ((cell = f->head) != NULL) {
 161                 f->head = cell->next;
 162
 163                 /* reset tail if this was the last element */
 164                 if (f->tail == cell)
 165                         f->tail = NULL;
 166
 167                 cell->next = NULL;
 168                 f->cells--;
 169         }
 170
 171         return cell;
 172 }
 173
 174 /* dequeue cell from fifo and copy on user space */
 175 int snd_seq_fifo_cell_out(struct snd_seq_fifo *f,
 176                           struct snd_seq_event_cell **cellp, int nonblock)
 177 {
 178         struct snd_seq_event_cell *cell;
 179         unsigned long flags;
 180         wait_queue_t wait;
 181
 182         if (snd_BUG_ON(!f))
 183                 return -EINVAL;
 184
 185         *cellp = NULL;
 186         init_waitqueue_entry(&wait, current);
 187         spin_lock_irqsave(&f->lock, flags);
 188         while ((cell = fifo_cell_out(f)) == NULL) {
 189                 if (nonblock) {
 190                         /* non-blocking - return immediately */
 191                         spin_unlock_irqrestore(&f->lock, flags);
 192                         return -EAGAIN;
 193                 }
 194                 set_current_state(TASK_INTERRUPTIBLE);
 195                 add_wait_queue(&f->input_sleep, &wait);
 196                 spin_unlock_irq(&f->lock);
 197                 schedule();
 198                 spin_lock_irq(&f->lock);
 199                 remove_wait_queue(&f->input_sleep, &wait);
 200                 if (signal_pending(current)) {
 201                         spin_unlock_irqrestore(&f->lock, flags);
 202                         return -ERESTARTSYS;
 203                 }
 204         }
 205         spin_unlock_irqrestore(&f->lock, flags);
 206         *cellp = cell;
 207
 208         return 0;
 209 }
 210
 211
 212 void snd_seq_fifo_cell_putback(struct snd_seq_fifo *f,
 213                                struct snd_seq_event_cell *cell)
 214 {
 215         unsigned long flags;
 216
 217         if (cell) {
 218                 spin_lock_irqsave(&f->lock, flags);
 219                 cell->next = f->head;
 220                 f->head = cell;
 221                 if (!f->tail)
 222                         f->tail = cell;
 223                 f->cells++;
 224                 spin_unlock_irqrestore(&f->lock, flags);
 225         }
 226 }
 227
 228
 229 /* polling; return non-zero if queue is available */
 230 int snd_seq_fifo_poll_wait(struct snd_seq_fifo *f, struct file *file,
 231                            poll_table *wait)
 232 {
 233         poll_wait(file, &f->input_sleep, wait);
 234         return (f->cells > 0);
 235 }
 236
 237 /* change the size of pool; all old events are removed */
 238 int snd_seq_fifo_resize(struct snd_seq_fifo *f, int poolsize)
 239 {
 240         unsigned long flags;
 241         struct snd_seq_pool *newpool, *oldpool;
 242         struct snd_seq_event_cell *cell, *next, *oldhead;
 243
 244         if (snd_BUG_ON(!f || !f->pool))
 245                 return -EINVAL;
 246
 247         /* allocate new pool */
 248         newpool = snd_seq_pool_new(poolsize);
 249         if (newpool == NULL)
 250                 return -ENOMEM;
 251         if (snd_seq_pool_init(newpool) < 0) {
 252                 snd_seq_pool_delete(&newpool);
 253                 return -ENOMEM;
 254         }
 255
 256         spin_lock_irqsave(&f->lock, flags);
 257         /* remember old pool */
 258         oldpool = f->pool;
 259         oldhead = f->head;
 260         /* exchange pools */
 261         f->pool = newpool;
 262         f->head = NULL;
 263         f->tail = NULL;
 264         f->cells = 0;
 265         /* NOTE: overflow flag is not cleared */
 266         spin_unlock_irqrestore(&f->lock, flags);
 267
 268         /* close the old pool and wait until all users are gone */
 269         snd_seq_pool_mark_closing(oldpool);
 270         snd_use_lock_sync(&f->use_lock);
 271
 272         /* release cells in old pool */
 273         for (cell = oldhead; cell; cell = next) {
 274                 next = cell->next;
 275                 snd_seq_cell_free(cell);
 276         }
 277         snd_seq_pool_delete(&oldpool);
 278
 279         return 0;
 280 }
 281
 282 /* get the number of unused cells safely */
 283 int snd_seq_fifo_unused_cells(struct snd_seq_fifo *f)
 284 {
 285         unsigned long flags;
 286         int cells;
 287
 288         if (!f)
 289                 return 0;
 290
 291         snd_use_lock_use(&f->use_lock);
 292         spin_lock_irqsave(&f->lock, flags);
 293         cells = snd_seq_unused_cells(f->pool);
 294         spin_unlock_irqrestore(&f->lock, flags);
 295         snd_use_lock_free(&f->use_lock);
 296         return cells;
 297 }