kernel/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         snd_seq_fifo_clear(f);
  74
  75         /* wake up clients if any */
  76         if (waitqueue_active(&f->input_sleep))
  77                 wake_up(&f->input_sleep);
  78
  79         /* release resources...*/
  80         /*....................*/
  81
  82         if (f->pool) {
  83                 snd_seq_pool_done(f->pool);
  84                 snd_seq_pool_delete(&f->pool);
  85         }
  86
  87         kfree(f);
  88 }
  89
  90 static struct snd_seq_event_cell *fifo_cell_out(struct snd_seq_fifo *f);
  91
  92 /* clear queue */
  93 void snd_seq_fifo_clear(struct snd_seq_fifo *f)
  94 {
  95         struct snd_seq_event_cell *cell;
  96         unsigned long flags;
  97
  98         /* clear overflow flag */
  99         atomic_set(&f->overflow, 0);
 100
 101         snd_use_lock_sync(&f->use_lock);
 102         spin_lock_irqsave(&f->lock, flags);
 103         /* drain the fifo */
 104         while ((cell = fifo_cell_out(f)) != NULL) {
 105                 snd_seq_cell_free(cell);
 106         }
 107         spin_unlock_irqrestore(&f->lock, flags);
 108 }
 109
 110
 111 /* enqueue event to fifo */
 112 int snd_seq_fifo_event_in(struct snd_seq_fifo *f,
 113                           struct snd_seq_event *event)
 114 {
 115         struct snd_seq_event_cell *cell;
 116         unsigned long flags;
 117         int err;
 118
 119         if (snd_BUG_ON(!f))
 120                 return -EINVAL;
 121
 122         snd_use_lock_use(&f->use_lock);
 123         err = snd_seq_event_dup(f->pool, event, &cell, 1, NULL); /* always non-blocking */
 124         if (err < 0) {
 125                 if ((err == -ENOMEM) || (err == -EAGAIN))
 126                         atomic_inc(&f->overflow);
 127                 snd_use_lock_free(&f->use_lock);
 128                 return err;
 129         }
 130
 131         /* append new cells to fifo */
 132         spin_lock_irqsave(&f->lock, flags);
 133         if (f->tail != NULL)
 134                 f->tail->next = cell;
 135         f->tail = cell;
 136         if (f->head == NULL)
 137                 f->head = cell;
 138         f->cells++;
 139         spin_unlock_irqrestore(&f->lock, flags);
 140
 141         /* wakeup client */
 142         if (waitqueue_active(&f->input_sleep))
 143                 wake_up(&f->input_sleep);
 144
 145         snd_use_lock_free(&f->use_lock);
 146
 147         return 0; /* success */
 148
 149 }
 150
 151 /* dequeue cell from fifo */
 152 static struct snd_seq_event_cell *fifo_cell_out(struct snd_seq_fifo *f)
 153 {
 154         struct snd_seq_event_cell *cell;
 155
 156         if ((cell = f->head) != NULL) {
 157                 f->head = cell->next;
 158
 159                 /* reset tail if this was the last element */
 160                 if (f->tail == cell)
 161                         f->tail = NULL;
 162
 163                 cell->next = NULL;
 164                 f->cells--;
 165         }
 166
 167         return cell;
 168 }
 169
 170 /* dequeue cell from fifo and copy on user space */
 171 int snd_seq_fifo_cell_out(struct snd_seq_fifo *f,
 172                           struct snd_seq_event_cell **cellp, int nonblock)
 173 {
 174         struct snd_seq_event_cell *cell;
 175         unsigned long flags;
 176         wait_queue_t wait;
 177
 178         if (snd_BUG_ON(!f))
 179                 return -EINVAL;
 180
 181         *cellp = NULL;
 182         init_waitqueue_entry(&wait, current);
 183         spin_lock_irqsave(&f->lock, flags);
 184         while ((cell = fifo_cell_out(f)) == NULL) {
 185                 if (nonblock) {
 186                         /* non-blocking - return immediately */
 187                         spin_unlock_irqrestore(&f->lock, flags);
 188                         return -EAGAIN;
 189                 }
 190                 set_current_state(TASK_INTERRUPTIBLE);
 191                 add_wait_queue(&f->input_sleep, &wait);
 192                 spin_unlock_irq(&f->lock);
 193                 schedule();
 194                 spin_lock_irq(&f->lock);
 195                 remove_wait_queue(&f->input_sleep, &wait);
 196                 if (signal_pending(current)) {
 197                         spin_unlock_irqrestore(&f->lock, flags);
 198                         return -ERESTARTSYS;
 199                 }
 200         }
 201         spin_unlock_irqrestore(&f->lock, flags);
 202         *cellp = cell;
 203
 204         return 0;
 205 }
 206
 207
 208 void snd_seq_fifo_cell_putback(struct snd_seq_fifo *f,
 209                                struct snd_seq_event_cell *cell)
 210 {
 211         unsigned long flags;
 212
 213         if (cell) {
 214                 spin_lock_irqsave(&f->lock, flags);
 215                 cell->next = f->head;
 216                 f->head = cell;
 217                 f->cells++;
 218                 spin_unlock_irqrestore(&f->lock, flags);
 219         }
 220 }
 221
 222
 223 /* polling; return non-zero if queue is available */
 224 int snd_seq_fifo_poll_wait(struct snd_seq_fifo *f, struct file *file,
 225                            poll_table *wait)
 226 {
 227         poll_wait(file, &f->input_sleep, wait);
 228         return (f->cells > 0);
 229 }
 230
 231 /* change the size of pool; all old events are removed */
 232 int snd_seq_fifo_resize(struct snd_seq_fifo *f, int poolsize)
 233 {
 234         unsigned long flags;
 235         struct snd_seq_pool *newpool, *oldpool;
 236         struct snd_seq_event_cell *cell, *next, *oldhead;
 237
 238         if (snd_BUG_ON(!f || !f->pool))
 239                 return -EINVAL;
 240
 241         /* allocate new pool */
 242         newpool = snd_seq_pool_new(poolsize);
 243         if (newpool == NULL)
 244                 return -ENOMEM;
 245         if (snd_seq_pool_init(newpool) < 0) {
 246                 snd_seq_pool_delete(&newpool);
 247                 return -ENOMEM;
 248         }
 249
 250         spin_lock_irqsave(&f->lock, flags);
 251         /* remember old pool */
 252         oldpool = f->pool;
 253         oldhead = f->head;
 254         /* exchange pools */
 255         f->pool = newpool;
 256         f->head = NULL;
 257         f->tail = NULL;
 258         f->cells = 0;
 259         /* NOTE: overflow flag is not cleared */
 260         spin_unlock_irqrestore(&f->lock, flags);
 261
 262         /* release cells in old pool */
 263         for (cell = oldhead; cell; cell = next) {
 264                 next = cell->next;
 265                 snd_seq_cell_free(cell);
 266         }
 267         snd_seq_pool_delete(&oldpool);
 268
 269         return 0;
 270 }