sound/drivers/pcsp/pcsp_lib.c

   1 /*
   2  * PC-Speaker driver for Linux
   3  *
   4  * Copyright (C) 1993-1997  Michael Beck
   5  * Copyright (C) 1997-2001  David Woodhouse
   6  * Copyright (C) 2001-2008  Stas Sergeev
   7  */
   8
   9 #include <linux/module.h>
  10 #include <linux/moduleparam.h>
  11 #include <sound/pcm.h>
  12 #include <linux/interrupt.h>
  13 #include <asm/io.h>
  14 #include "pcsp.h"
  15
  16 static int nforce_wa;
  17 module_param(nforce_wa, bool, 0444);
  18 MODULE_PARM_DESC(nforce_wa, "Apply NForce chipset workaround "
  19                 "(expect bad sound)");
  20
  21 static void pcsp_start_timer(unsigned long dummy)
  22 {
  23         hrtimer_start(&pcsp_chip.timer, ktime_set(0, 0), HRTIMER_MODE_REL);
  24 }
  25
  26 /*
  27  * We need the hrtimer_start as a tasklet to avoid
  28  * the nasty locking problem. :(
  29  * The problem:
  30  * - The timer handler is called with the cpu_base->lock
  31  *   already held by hrtimer code.
  32  * - snd_pcm_period_elapsed() takes the
  33  *   substream->self_group.lock.
  34  * So far so good.
  35  * But the snd_pcsp_trigger() is called with the
  36  * substream->self_group.lock held, and it calls
  37  * hrtimer_start(), which takes the cpu_base->lock.
  38  * You see the problem. We have the code pathes
  39  * which take two locks in a reverse order. This
  40  * can deadlock and the lock validator complains.
  41  * The only solution I could find was to move the
  42  * hrtimer_start() into a tasklet. -stsp
  43  */
  44 static DECLARE_TASKLET(pcsp_start_timer_tasklet, pcsp_start_timer, 0);
  45
  46 enum hrtimer_restart pcsp_do_timer(struct hrtimer *handle)
  47 {
  48         unsigned long flags;
  49         unsigned char timer_cnt, val;
  50         int periods_elapsed;
  51         u64 ns;
  52         size_t period_bytes, buffer_bytes;
  53         struct snd_pcm_substream *substream;
  54         struct snd_pcm_runtime *runtime;
  55         struct snd_pcsp *chip = container_of(handle, struct snd_pcsp, timer);
  56
  57         if (chip->thalf) {
  58                 outb(chip->val61, 0x61);
  59                 chip->thalf = 0;
  60                 if (!atomic_read(&chip->timer_active))
  61                         return HRTIMER_NORESTART;
  62                 hrtimer_forward(&chip->timer, chip->timer.expires,
  63                                 ktime_set(0, chip->ns_rem));
  64                 return HRTIMER_RESTART;
  65         }
  66
  67         /* hrtimer calls us from both hardirq and softirq contexts,
  68          * so irqsave :( */
  69         spin_lock_irqsave(&chip->substream_lock, flags);
  70         /* Takashi Iwai says regarding this extra lock:
  71
  72         If the irq handler handles some data on the DMA buffer, it should
  73         do snd_pcm_stream_lock().
  74         That protects basically against all races among PCM callbacks, yes.
  75         However, there are two remaining issues:
  76         1. The substream pointer you try to lock isn't protected _before_
  77           this lock yet.
  78         2. snd_pcm_period_elapsed() itself acquires the lock.
  79         The requirement of another lock is because of 1.  When you get
  80         chip->playback_substream, it's not protected.
  81         Keeping this lock while snd_pcm_period_elapsed() assures the substream
  82         is still protected (at least, not released).  And the other status is
  83         handled properly inside snd_pcm_stream_lock() in
  84         snd_pcm_period_elapsed().
  85
  86         */
  87         if (!chip->playback_substream)
  88                 goto exit_nr_unlock1;
  89         substream = chip->playback_substream;
  90         snd_pcm_stream_lock(substream);
  91         if (!atomic_read(&chip->timer_active))
  92                 goto exit_nr_unlock2;
  93
  94         runtime = substream->runtime;
  95         /* assume it is u8 mono */
  96         val = runtime->dma_area[chip->playback_ptr];
  97         timer_cnt = val * CUR_DIV() / 256;
  98
  99         if (timer_cnt && chip->enable) {
 100                 spin_lock(&i8253_lock);
 101                 if (!nforce_wa) {
 102                         outb_p(chip->val61, 0x61);
 103                         outb_p(timer_cnt, 0x42);
 104                         outb(chip->val61 ^ 1, 0x61);
 105                 } else {
 106                         outb(chip->val61 ^ 2, 0x61);
 107                         chip->thalf = 1;
 108                 }
 109                 spin_unlock(&i8253_lock);
 110         }
 111
 112         period_bytes = snd_pcm_lib_period_bytes(substream);
 113         buffer_bytes = snd_pcm_lib_buffer_bytes(substream);
 114         chip->playback_ptr += PCSP_INDEX_INC();
 115         periods_elapsed = chip->playback_ptr - chip->period_ptr;
 116         if (periods_elapsed < 0) {
 117                 printk(KERN_WARNING "PCSP: playback_ptr inconsistent "
 118                         "(%zi %zi %zi)\n",
 119                         chip->playback_ptr, period_bytes, buffer_bytes);
 120                 periods_elapsed += buffer_bytes;
 121         }
 122         periods_elapsed /= period_bytes;
 123         /* wrap the pointer _before_ calling snd_pcm_period_elapsed(),
 124          * or ALSA will BUG on us. */
 125         chip->playback_ptr %= buffer_bytes;
 126
 127         snd_pcm_stream_unlock(substream);
 128
 129         if (periods_elapsed) {
 130                 snd_pcm_period_elapsed(substream);
 131                 chip->period_ptr += periods_elapsed * period_bytes;
 132                 chip->period_ptr %= buffer_bytes;
 133         }
 134
 135         spin_unlock_irqrestore(&chip->substream_lock, flags);
 136
 137         if (!atomic_read(&chip->timer_active))
 138                 return HRTIMER_NORESTART;
 139
 140         chip->ns_rem = PCSP_PERIOD_NS();
 141         ns = (chip->thalf ? PCSP_CALC_NS(timer_cnt) : chip->ns_rem);
 142         chip->ns_rem -= ns;
 143         hrtimer_forward(&chip->timer, chip->timer.expires, ktime_set(0, ns));
 144         return HRTIMER_RESTART;
 145
 146 exit_nr_unlock2:
 147         snd_pcm_stream_unlock(substream);
 148 exit_nr_unlock1:
 149         spin_unlock_irqrestore(&chip->substream_lock, flags);
 150         return HRTIMER_NORESTART;
 151 }
 152
 153 static void pcsp_start_playing(struct snd_pcsp *chip)
 154 {
 155 #if PCSP_DEBUG
 156         printk(KERN_INFO "PCSP: start_playing called\n");
 157 #endif
 158         if (atomic_read(&chip->timer_active)) {
 159                 printk(KERN_ERR "PCSP: Timer already active\n");
 160                 return;
 161         }
 162
 163         spin_lock(&i8253_lock);
 164         chip->val61 = inb(0x61) | 0x03;
 165         outb_p(0x92, 0x43);     /* binary, mode 1, LSB only, ch 2 */
 166         spin_unlock(&i8253_lock);
 167         atomic_set(&chip->timer_active, 1);
 168         chip->thalf = 0;
 169
 170         tasklet_schedule(&pcsp_start_timer_tasklet);
 171 }
 172
 173 static void pcsp_stop_playing(struct snd_pcsp *chip)
 174 {
 175 #if PCSP_DEBUG
 176         printk(KERN_INFO "PCSP: stop_playing called\n");
 177 #endif
 178         if (!atomic_read(&chip->timer_active))
 179                 return;
 180
 181         atomic_set(&chip->timer_active, 0);
 182         spin_lock(&i8253_lock);
 183         /* restore the timer */
 184         outb_p(0xb6, 0x43);     /* binary, mode 3, LSB/MSB, ch 2 */
 185         outb(chip->val61 & 0xFC, 0x61);
 186         spin_unlock(&i8253_lock);
 187 }
 188
 189 static int snd_pcsp_playback_close(struct snd_pcm_substream *substream)
 190 {
 191         struct snd_pcsp *chip = snd_pcm_substream_chip(substream);
 192 #if PCSP_DEBUG
 193         printk(KERN_INFO "PCSP: close called\n");
 194 #endif
 195         if (atomic_read(&chip->timer_active)) {
 196                 printk(KERN_ERR "PCSP: timer still active\n");
 197                 pcsp_stop_playing(chip);
 198         }
 199         spin_lock_irq(&chip->substream_lock);
 200         chip->playback_substream = NULL;
 201         spin_unlock_irq(&chip->substream_lock);
 202         return 0;
 203 }
 204
 205 static int snd_pcsp_playback_hw_params(struct snd_pcm_substream *substream,
 206                                        struct snd_pcm_hw_params *hw_params)
 207 {
 208         int err;
 209         err = snd_pcm_lib_malloc_pages(substream,
 210                                       params_buffer_bytes(hw_params));
 211         if (err < 0)
 212                 return err;
 213         return 0;
 214 }
 215
 216 static int snd_pcsp_playback_hw_free(struct snd_pcm_substream *substream)
 217 {
 218 #if PCSP_DEBUG
 219         printk(KERN_INFO "PCSP: hw_free called\n");
 220 #endif
 221         return snd_pcm_lib_free_pages(substream);
 222 }
 223
 224 static int snd_pcsp_playback_prepare(struct snd_pcm_substream *substream)
 225 {
 226         struct snd_pcsp *chip = snd_pcm_substream_chip(substream);
 227 #if PCSP_DEBUG
 228         printk(KERN_INFO "PCSP: prepare called, "
 229                         "size=%zi psize=%zi f=%zi f1=%i\n",
 230                         snd_pcm_lib_buffer_bytes(substream),
 231                         snd_pcm_lib_period_bytes(substream),
 232                         snd_pcm_lib_buffer_bytes(substream) /
 233                         snd_pcm_lib_period_bytes(substream),
 234                         substream->runtime->periods);
 235 #endif
 236         chip->playback_ptr = 0;
 237         chip->period_ptr = 0;
 238         return 0;
 239 }
 240
 241 static int snd_pcsp_trigger(struct snd_pcm_substream *substream, int cmd)
 242 {
 243         struct snd_pcsp *chip = snd_pcm_substream_chip(substream);
 244 #if PCSP_DEBUG
 245         printk(KERN_INFO "PCSP: trigger called\n");
 246 #endif
 247         switch (cmd) {
 248         case SNDRV_PCM_TRIGGER_START:
 249         case SNDRV_PCM_TRIGGER_RESUME:
 250                 pcsp_start_playing(chip);
 251                 break;
 252         case SNDRV_PCM_TRIGGER_STOP:
 253         case SNDRV_PCM_TRIGGER_SUSPEND:
 254                 pcsp_stop_playing(chip);
 255                 break;
 256         default:
 257                 return -EINVAL;
 258         }
 259         return 0;
 260 }
 261
 262 static snd_pcm_uframes_t snd_pcsp_playback_pointer(struct snd_pcm_substream
 263                                                    *substream)
 264 {
 265         struct snd_pcsp *chip = snd_pcm_substream_chip(substream);
 266         return bytes_to_frames(substream->runtime, chip->playback_ptr);
 267 }
 268
 269 static struct snd_pcm_hardware snd_pcsp_playback = {
 270         .info = (SNDRV_PCM_INFO_INTERLEAVED |
 271                  SNDRV_PCM_INFO_HALF_DUPLEX |
 272                  SNDRV_PCM_INFO_MMAP | SNDRV_PCM_INFO_MMAP_VALID),
 273         .formats = SNDRV_PCM_FMTBIT_U8,
 274         .rates = SNDRV_PCM_RATE_KNOT,
 275         .rate_min = PCSP_DEFAULT_SRATE,
 276         .rate_max = PCSP_DEFAULT_SRATE,
 277         .channels_min = 1,
 278         .channels_max = 1,
 279         .buffer_bytes_max = PCSP_BUFFER_SIZE,
 280         .period_bytes_min = 64,
 281         .period_bytes_max = PCSP_MAX_PERIOD_SIZE,
 282         .periods_min = 2,
 283         .periods_max = PCSP_MAX_PERIODS,
 284         .fifo_size = 0,
 285 };
 286
 287 static int snd_pcsp_playback_open(struct snd_pcm_substream *substream)
 288 {
 289         struct snd_pcsp *chip = snd_pcm_substream_chip(substream);
 290         struct snd_pcm_runtime *runtime = substream->runtime;
 291 #if PCSP_DEBUG
 292         printk(KERN_INFO "PCSP: open called\n");
 293 #endif
 294         if (atomic_read(&chip->timer_active)) {
 295                 printk(KERN_ERR "PCSP: still active!!\n");
 296                 return -EBUSY;
 297         }
 298         runtime->hw = snd_pcsp_playback;
 299         spin_lock_irq(&chip->substream_lock);
 300         chip->playback_substream = substream;
 301         spin_unlock_irq(&chip->substream_lock);
 302         return 0;
 303 }
 304
 305 static struct snd_pcm_ops snd_pcsp_playback_ops = {
 306         .open = snd_pcsp_playback_open,
 307         .close = snd_pcsp_playback_close,
 308         .ioctl = snd_pcm_lib_ioctl,
 309         .hw_params = snd_pcsp_playback_hw_params,
 310         .hw_free = snd_pcsp_playback_hw_free,
 311         .prepare = snd_pcsp_playback_prepare,
 312         .trigger = snd_pcsp_trigger,
 313         .pointer = snd_pcsp_playback_pointer,
 314 };
 315
 316 int __devinit snd_pcsp_new_pcm(struct snd_pcsp *chip)
 317 {
 318         int err;
 319
 320         err = snd_pcm_new(chip->card, "pcspeaker", 0, 1, 0, &chip->pcm);
 321         if (err < 0)
 322                 return err;
 323
 324         snd_pcm_set_ops(chip->pcm, SNDRV_PCM_STREAM_PLAYBACK,
 325                         &snd_pcsp_playback_ops);
 326
 327         chip->pcm->private_data = chip;
 328         chip->pcm->info_flags = SNDRV_PCM_INFO_HALF_DUPLEX;
 329         strcpy(chip->pcm->name, "pcsp");
 330
 331         snd_pcm_lib_preallocate_pages_for_all(chip->pcm,
 332                                               SNDRV_DMA_TYPE_CONTINUOUS,
 333                                               snd_dma_continuous_data
 334                                               (GFP_KERNEL), PCSP_BUFFER_SIZE,
 335                                               PCSP_BUFFER_SIZE);
 336
 337         return 0;
 338 }