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 #define DMIX_WANTS_S16  1
  22
  23 static void pcsp_start_timer(unsigned long dummy)
  24 {
  25         hrtimer_start(&pcsp_chip.timer, ktime_set(0, 0), HRTIMER_MODE_REL);
  26 }
  27
  28 /*
  29  * We need the hrtimer_start as a tasklet to avoid
  30  * the nasty locking problem. :(
  31  * The problem:
  32  * - The timer handler is called with the cpu_base->lock
  33  *   already held by hrtimer code.
  34  * - snd_pcm_period_elapsed() takes the
  35  *   substream->self_group.lock.
  36  * So far so good.
  37  * But the snd_pcsp_trigger() is called with the
  38  * substream->self_group.lock held, and it calls
  39  * hrtimer_start(), which takes the cpu_base->lock.
  40  * You see the problem. We have the code pathes
  41  * which take two locks in a reverse order. This
  42  * can deadlock and the lock validator complains.
  43  * The only solution I could find was to move the
  44  * hrtimer_start() into a tasklet. -stsp
  45  */
  46 static DECLARE_TASKLET(pcsp_start_timer_tasklet, pcsp_start_timer, 0);
  47
  48 enum hrtimer_restart pcsp_do_timer(struct hrtimer *handle)
  49 {
  50         unsigned long flags;
  51         unsigned char timer_cnt, val;
  52         int fmt_size, periods_elapsed;
  53         u64 ns;
  54         size_t period_bytes, buffer_bytes;
  55         struct snd_pcm_substream *substream;
  56         struct snd_pcm_runtime *runtime;
  57         struct snd_pcsp *chip = container_of(handle, struct snd_pcsp, timer);
  58
  59         if (chip->thalf) {
  60                 outb(chip->val61, 0x61);
  61                 chip->thalf = 0;
  62                 if (!atomic_read(&chip->timer_active))
  63                         return HRTIMER_NORESTART;
  64                 hrtimer_forward(&chip->timer, chip->timer.expires,
  65                                 ktime_set(0, chip->ns_rem));
  66                 return HRTIMER_RESTART;
  67         }
  68
  69         /* hrtimer calls us from both hardirq and softirq contexts,
  70          * so irqsave :( */
  71         spin_lock_irqsave(&chip->substream_lock, flags);
  72         /* Takashi Iwai says regarding this extra lock:
  73
  74         If the irq handler handles some data on the DMA buffer, it should
  75         do snd_pcm_stream_lock().
  76         That protects basically against all races among PCM callbacks, yes.
  77         However, there are two remaining issues:
  78         1. The substream pointer you try to lock isn't protected _before_
  79           this lock yet.
  80         2. snd_pcm_period_elapsed() itself acquires the lock.
  81         The requirement of another lock is because of 1.  When you get
  82         chip->playback_substream, it's not protected.
  83         Keeping this lock while snd_pcm_period_elapsed() assures the substream
  84         is still protected (at least, not released).  And the other status is
  85         handled properly inside snd_pcm_stream_lock() in
  86         snd_pcm_period_elapsed().
  87
  88         */
  89         if (!chip->playback_substream)
  90                 goto exit_nr_unlock1;
  91         substream = chip->playback_substream;
  92         snd_pcm_stream_lock(substream);
  93         if (!atomic_read(&chip->timer_active))
  94                 goto exit_nr_unlock2;
  95
  96         runtime = substream->runtime;
  97         fmt_size = snd_pcm_format_physical_width(runtime->format) >> 3;
  98         /* assume it is mono! */
  99         val = runtime->dma_area[chip->playback_ptr + fmt_size - 1];
 100         if (snd_pcm_format_signed(runtime->format))
 101                 val ^= 0x80;
 102         timer_cnt = val * CUR_DIV() / 256;
 103
 104         if (timer_cnt && chip->enable) {
 105                 spin_lock(&i8253_lock);
 106                 if (!nforce_wa) {
 107                         outb_p(chip->val61, 0x61);
 108                         outb_p(timer_cnt, 0x42);
 109                         outb(chip->val61 ^ 1, 0x61);
 110                 } else {
 111                         outb(chip->val61 ^ 2, 0x61);
 112                         chip->thalf = 1;
 113                 }
 114                 spin_unlock(&i8253_lock);
 115         }
 116
 117         period_bytes = snd_pcm_lib_period_bytes(substream);
 118         buffer_bytes = snd_pcm_lib_buffer_bytes(substream);
 119         chip->playback_ptr += PCSP_INDEX_INC() * fmt_size;
 120         periods_elapsed = chip->playback_ptr - chip->period_ptr;
 121         if (periods_elapsed < 0) {
 122 #if PCSP_DEBUG
 123                 printk(KERN_INFO "PCSP: buffer_bytes mod period_bytes != 0 ? "
 124                         "(%zi %zi %zi)\n",
 125                         chip->playback_ptr, period_bytes, buffer_bytes);
 126 #endif
 127                 periods_elapsed += buffer_bytes;
 128         }
 129         periods_elapsed /= period_bytes;
 130         /* wrap the pointer _before_ calling snd_pcm_period_elapsed(),
 131          * or ALSA will BUG on us. */
 132         chip->playback_ptr %= buffer_bytes;
 133
 134         snd_pcm_stream_unlock(substream);
 135
 136         if (periods_elapsed) {
 137                 snd_pcm_period_elapsed(substream);
 138                 chip->period_ptr += periods_elapsed * period_bytes;
 139                 chip->period_ptr %= buffer_bytes;
 140         }
 141
 142         spin_unlock_irqrestore(&chip->substream_lock, flags);
 143
 144         if (!atomic_read(&chip->timer_active))
 145                 return HRTIMER_NORESTART;
 146
 147         chip->ns_rem = PCSP_PERIOD_NS();
 148         ns = (chip->thalf ? PCSP_CALC_NS(timer_cnt) : chip->ns_rem);
 149         chip->ns_rem -= ns;
 150         hrtimer_forward(&chip->timer, chip->timer.expires, ktime_set(0, ns));
 151         return HRTIMER_RESTART;
 152
 153 exit_nr_unlock2:
 154         snd_pcm_stream_unlock(substream);
 155 exit_nr_unlock1:
 156         spin_unlock_irqrestore(&chip->substream_lock, flags);
 157         return HRTIMER_NORESTART;
 158 }
 159
 160 static void pcsp_start_playing(struct snd_pcsp *chip)
 161 {
 162 #if PCSP_DEBUG
 163         printk(KERN_INFO "PCSP: start_playing called\n");
 164 #endif
 165         if (atomic_read(&chip->timer_active)) {
 166                 printk(KERN_ERR "PCSP: Timer already active\n");
 167                 return;
 168         }
 169
 170         spin_lock(&i8253_lock);
 171         chip->val61 = inb(0x61) | 0x03;
 172         outb_p(0x92, 0x43);     /* binary, mode 1, LSB only, ch 2 */
 173         spin_unlock(&i8253_lock);
 174         atomic_set(&chip->timer_active, 1);
 175         chip->thalf = 0;
 176
 177         tasklet_schedule(&pcsp_start_timer_tasklet);
 178 }
 179
 180 static void pcsp_stop_playing(struct snd_pcsp *chip)
 181 {
 182 #if PCSP_DEBUG
 183         printk(KERN_INFO "PCSP: stop_playing called\n");
 184 #endif
 185         if (!atomic_read(&chip->timer_active))
 186                 return;
 187
 188         atomic_set(&chip->timer_active, 0);
 189         spin_lock(&i8253_lock);
 190         /* restore the timer */
 191         outb_p(0xb6, 0x43);     /* binary, mode 3, LSB/MSB, ch 2 */
 192         outb(chip->val61 & 0xFC, 0x61);
 193         spin_unlock(&i8253_lock);
 194 }
 195
 196 static int snd_pcsp_playback_close(struct snd_pcm_substream *substream)
 197 {
 198         struct snd_pcsp *chip = snd_pcm_substream_chip(substream);
 199 #if PCSP_DEBUG
 200         printk(KERN_INFO "PCSP: close called\n");
 201 #endif
 202         if (atomic_read(&chip->timer_active)) {
 203                 printk(KERN_ERR "PCSP: timer still active\n");
 204                 pcsp_stop_playing(chip);
 205         }
 206         spin_lock_irq(&chip->substream_lock);
 207         chip->playback_substream = NULL;
 208         spin_unlock_irq(&chip->substream_lock);
 209         return 0;
 210 }
 211
 212 static int snd_pcsp_playback_hw_params(struct snd_pcm_substream *substream,
 213                                        struct snd_pcm_hw_params *hw_params)
 214 {
 215         int err;
 216         err = snd_pcm_lib_malloc_pages(substream,
 217                                       params_buffer_bytes(hw_params));
 218         if (err < 0)
 219                 return err;
 220         return 0;
 221 }
 222
 223 static int snd_pcsp_playback_hw_free(struct snd_pcm_substream *substream)
 224 {
 225 #if PCSP_DEBUG
 226         printk(KERN_INFO "PCSP: hw_free called\n");
 227 #endif
 228         return snd_pcm_lib_free_pages(substream);
 229 }
 230
 231 static int snd_pcsp_playback_prepare(struct snd_pcm_substream *substream)
 232 {
 233         struct snd_pcsp *chip = snd_pcm_substream_chip(substream);
 234 #if PCSP_DEBUG
 235         printk(KERN_INFO "PCSP: prepare called, "
 236                         "size=%zi psize=%zi f=%zi f1=%i\n",
 237                         snd_pcm_lib_buffer_bytes(substream),
 238                         snd_pcm_lib_period_bytes(substream),
 239                         snd_pcm_lib_buffer_bytes(substream) /
 240                         snd_pcm_lib_period_bytes(substream),
 241                         substream->runtime->periods);
 242 #endif
 243         chip->playback_ptr = 0;
 244         chip->period_ptr = 0;
 245         return 0;
 246 }
 247
 248 static int snd_pcsp_trigger(struct snd_pcm_substream *substream, int cmd)
 249 {
 250         struct snd_pcsp *chip = snd_pcm_substream_chip(substream);
 251 #if PCSP_DEBUG
 252         printk(KERN_INFO "PCSP: trigger called\n");
 253 #endif
 254         switch (cmd) {
 255         case SNDRV_PCM_TRIGGER_START:
 256         case SNDRV_PCM_TRIGGER_RESUME:
 257                 pcsp_start_playing(chip);
 258                 break;
 259         case SNDRV_PCM_TRIGGER_STOP:
 260         case SNDRV_PCM_TRIGGER_SUSPEND:
 261                 pcsp_stop_playing(chip);
 262                 break;
 263         default:
 264                 return -EINVAL;
 265         }
 266         return 0;
 267 }
 268
 269 static snd_pcm_uframes_t snd_pcsp_playback_pointer(struct snd_pcm_substream
 270                                                    *substream)
 271 {
 272         struct snd_pcsp *chip = snd_pcm_substream_chip(substream);
 273         return bytes_to_frames(substream->runtime, chip->playback_ptr);
 274 }
 275
 276 static struct snd_pcm_hardware snd_pcsp_playback = {
 277         .info = (SNDRV_PCM_INFO_INTERLEAVED |
 278                  SNDRV_PCM_INFO_HALF_DUPLEX |
 279                  SNDRV_PCM_INFO_MMAP | SNDRV_PCM_INFO_MMAP_VALID),
 280         .formats = (SNDRV_PCM_FMTBIT_U8
 281 #if DMIX_WANTS_S16
 282                     | SNDRV_PCM_FMTBIT_S16_LE
 283 #endif
 284             ),
 285         .rates = SNDRV_PCM_RATE_KNOT,
 286         .rate_min = PCSP_DEFAULT_SRATE,
 287         .rate_max = PCSP_DEFAULT_SRATE,
 288         .channels_min = 1,
 289         .channels_max = 1,
 290         .buffer_bytes_max = PCSP_BUFFER_SIZE,
 291         .period_bytes_min = 64,
 292         .period_bytes_max = PCSP_MAX_PERIOD_SIZE,
 293         .periods_min = 2,
 294         .periods_max = PCSP_MAX_PERIODS,
 295         .fifo_size = 0,
 296 };
 297
 298 static int snd_pcsp_playback_open(struct snd_pcm_substream *substream)
 299 {
 300         struct snd_pcsp *chip = snd_pcm_substream_chip(substream);
 301         struct snd_pcm_runtime *runtime = substream->runtime;
 302 #if PCSP_DEBUG
 303         printk(KERN_INFO "PCSP: open called\n");
 304 #endif
 305         if (atomic_read(&chip->timer_active)) {
 306                 printk(KERN_ERR "PCSP: still active!!\n");
 307                 return -EBUSY;
 308         }
 309         runtime->hw = snd_pcsp_playback;
 310         spin_lock_irq(&chip->substream_lock);
 311         chip->playback_substream = substream;
 312         spin_unlock_irq(&chip->substream_lock);
 313         return 0;
 314 }
 315
 316 static struct snd_pcm_ops snd_pcsp_playback_ops = {
 317         .open = snd_pcsp_playback_open,
 318         .close = snd_pcsp_playback_close,
 319         .ioctl = snd_pcm_lib_ioctl,
 320         .hw_params = snd_pcsp_playback_hw_params,
 321         .hw_free = snd_pcsp_playback_hw_free,
 322         .prepare = snd_pcsp_playback_prepare,
 323         .trigger = snd_pcsp_trigger,
 324         .pointer = snd_pcsp_playback_pointer,
 325 };
 326
 327 int __devinit snd_pcsp_new_pcm(struct snd_pcsp *chip)
 328 {
 329         int err;
 330
 331         err = snd_pcm_new(chip->card, "pcspeaker", 0, 1, 0, &chip->pcm);
 332         if (err < 0)
 333                 return err;
 334
 335         snd_pcm_set_ops(chip->pcm, SNDRV_PCM_STREAM_PLAYBACK,
 336                         &snd_pcsp_playback_ops);
 337
 338         chip->pcm->private_data = chip;
 339         chip->pcm->info_flags = SNDRV_PCM_INFO_HALF_DUPLEX;
 340         strcpy(chip->pcm->name, "pcsp");
 341
 342         snd_pcm_lib_preallocate_pages_for_all(chip->pcm,
 343                                               SNDRV_DMA_TYPE_CONTINUOUS,
 344                                               snd_dma_continuous_data
 345                                               (GFP_KERNEL), PCSP_BUFFER_SIZE,
 346                                               PCSP_BUFFER_SIZE);
 347
 348         return 0;
 349 }