Quelle  pcsp_lib.c   Sprache: C

// SPDX-License-Identifier: GPL-2.0
/*
 * PC-Speaker driver for Linux
 *
 * Copyright (C) 1993-1997  Michael Beck
 * Copyright (C) 1997-2001  David Woodhouse
 * Copyright (C) 2001-2008  Stas Sergeev
 */

#include <linux/module.h>
#include <linux/gfp.h>
#include <linux/moduleparam.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <sound/core.h>
#include <sound/pcm.h>
#include "pcsp.h"

static bool nforce_wa;
module_param(nforce_wa, bool, 0444);
MODULE_PARM_DESC(nforce_wa, "Apply NForce chipset workaround "
  "(expect bad sound)");

#define DMIX_WANTS_S16 1

/*
 * Call snd_pcm_period_elapsed in a work
 * This avoids spinlock messes and long-running irq contexts
 */
static void pcsp_call_pcm_elapsed(struct work_struct *work)
{
 if (atomic_read(&pcsp_chip.timer_active)) {
  struct snd_pcm_substream *substream;
  substream = pcsp_chip.playback_substream;
  if (substream)
   snd_pcm_period_elapsed(substream);
 }
}

static DECLARE_WORK(pcsp_pcm_work, pcsp_call_pcm_elapsed);

/* write the port and returns the next expire time in ns;
 * called at the trigger-start and in hrtimer callback
 */
static u64 pcsp_timer_update(struct snd_pcsp *chip)
{
 unsigned char timer_cnt, val;
 u64 ns;
 struct snd_pcm_substream *substream;
 struct snd_pcm_runtime *runtime;
 unsigned long flags;

 if (chip->thalf) {
  outb(chip->val61, 0x61);
  chip->thalf = 0;
  return chip->ns_rem;
 }

 substream = chip->playback_substream;
 if (!substream)
  return 0;

 runtime = substream->runtime;
 /* assume it is mono! */
 val = runtime->dma_area[chip->playback_ptr + chip->fmt_size - 1];
 if (chip->is_signed)
  val ^= 0x80;
 timer_cnt = val * CUR_DIV() / 256;

 if (timer_cnt && chip->enable) {
  raw_spin_lock_irqsave(&i8253_lock, flags);
  if (!nforce_wa) {
   outb_p(chip->val61, 0x61);
   outb_p(timer_cnt, 0x42);
   outb(chip->val61 ^ 1, 0x61);
  } else {
   outb(chip->val61 ^ 2, 0x61);
   chip->thalf = 1;
  }
  raw_spin_unlock_irqrestore(&i8253_lock, flags);
 }

 chip->ns_rem = PCSP_PERIOD_NS();
 ns = (chip->thalf ? PCSP_CALC_NS(timer_cnt) : chip->ns_rem);
 chip->ns_rem -= ns;
 return ns;
}

static void pcsp_pointer_update(struct snd_pcsp *chip)
{
 struct snd_pcm_substream *substream;
 size_t period_bytes, buffer_bytes;
 int periods_elapsed;
 unsigned long flags;

 /* update the playback position */
 substream = chip->playback_substream;
 if (!substream)
  return;

 period_bytes = snd_pcm_lib_period_bytes(substream);
 buffer_bytes = snd_pcm_lib_buffer_bytes(substream);

 spin_lock_irqsave(&chip->substream_lock, flags);
 chip->playback_ptr += PCSP_INDEX_INC() * chip->fmt_size;
 periods_elapsed = chip->playback_ptr - chip->period_ptr;
 if (periods_elapsed < 0) {
#if PCSP_DEBUG
  dev_dbg(chip->card->dev,
   "PCSP: buffer_bytes mod period_bytes != 0 ? (%zi %zi %zi)\n",
   chip->playback_ptr, period_bytes, buffer_bytes);
#endif
  periods_elapsed += buffer_bytes;
 }
 periods_elapsed /= period_bytes;
 /* wrap the pointer _before_ calling snd_pcm_period_elapsed(),
 * or ALSA will BUG on us. */
 chip->playback_ptr %= buffer_bytes;

 if (periods_elapsed) {
  chip->period_ptr += periods_elapsed * period_bytes;
  chip->period_ptr %= buffer_bytes;
  queue_work(system_highpri_wq, &pcsp_pcm_work);
 }
 spin_unlock_irqrestore(&chip->substream_lock, flags);
}

enum hrtimer_restart pcsp_do_timer(struct hrtimer *handle)
{
 struct snd_pcsp *chip = container_of(handle, struct snd_pcsp, timer);
 int pointer_update;
 u64 ns;

 if (!atomic_read(&chip->timer_active) || !chip->playback_substream)
  return HRTIMER_NORESTART;

 pointer_update = !chip->thalf;
 ns = pcsp_timer_update(chip);
 if (!ns) {
  dev_warn(chip->card->dev, "PCSP: unexpected stop\n");
  return HRTIMER_NORESTART;
 }

 if (pointer_update)
  pcsp_pointer_update(chip);

 hrtimer_forward_now(handle, ns_to_ktime(ns));

 return HRTIMER_RESTART;
}

static int pcsp_start_playing(struct snd_pcsp *chip)
{
#if PCSP_DEBUG
 dev_dbg(chip->card->dev, "PCSP: start_playing called\n");
#endif
 if (atomic_read(&chip->timer_active)) {
  dev_err(chip->card->dev, "PCSP: Timer already active\n");
  return -EIO;
 }

 raw_spin_lock(&i8253_lock);
 chip->val61 = inb(0x61) | 0x03;
 outb_p(0x92, 0x43); /* binary, mode 1, LSB only, ch 2 */
 raw_spin_unlock(&i8253_lock);
 atomic_set(&chip->timer_active, 1);
 chip->thalf = 0;

 hrtimer_start(&pcsp_chip.timer, 0, HRTIMER_MODE_REL);
 return 0;
}

static void pcsp_stop_playing(struct snd_pcsp *chip)
{
#if PCSP_DEBUG
 dev_dbg(chip->card->dev, "PCSP: stop_playing called\n");
#endif
 if (!atomic_read(&chip->timer_active))
  return;

 atomic_set(&chip->timer_active, 0);
 raw_spin_lock(&i8253_lock);
 /* restore the timer */
 outb_p(0xb6, 0x43); /* binary, mode 3, LSB/MSB, ch 2 */
 outb(chip->val61 & 0xFC, 0x61);
 raw_spin_unlock(&i8253_lock);
}

/*
 * Force to stop and sync the stream
 */
void pcsp_sync_stop(struct snd_pcsp *chip)
{
 local_irq_disable();
 pcsp_stop_playing(chip);
 local_irq_enable();
 hrtimer_cancel(&chip->timer);
 cancel_work_sync(&pcsp_pcm_work);
}

static int snd_pcsp_playback_close(struct snd_pcm_substream *substream)
{
 struct snd_pcsp *chip = snd_pcm_substream_chip(substream);
#if PCSP_DEBUG
 dev_dbg(chip->card->dev, "PCSP: close called\n");
#endif
 pcsp_sync_stop(chip);
 chip->playback_substream = NULL;
 return 0;
}

static int snd_pcsp_playback_hw_params(struct snd_pcm_substream *substream,
           struct snd_pcm_hw_params *hw_params)
{
 struct snd_pcsp *chip = snd_pcm_substream_chip(substream);
 pcsp_sync_stop(chip);
 return 0;
}

static int snd_pcsp_playback_hw_free(struct snd_pcm_substream *substream)
{
 struct snd_pcsp *chip = snd_pcm_substream_chip(substream);
#if PCSP_DEBUG
 dev_dbg(chip->card->dev, "PCSP: hw_free called\n");
#endif
 pcsp_sync_stop(chip);
 return 0;
}

static int snd_pcsp_playback_prepare(struct snd_pcm_substream *substream)
{
 struct snd_pcsp *chip = snd_pcm_substream_chip(substream);
 pcsp_sync_stop(chip);
 chip->playback_ptr = 0;
 chip->period_ptr = 0;
 chip->fmt_size =
  snd_pcm_format_physical_width(substream->runtime->format) >> 3;
 chip->is_signed = snd_pcm_format_signed(substream->runtime->format);
#if PCSP_DEBUG
 dev_dbg(chip->card->dev, "PCSP: prepare called, size=%zi psize=%zi f=%zi f1=%i fsize=%i\n",
  snd_pcm_lib_buffer_bytes(substream),
  snd_pcm_lib_period_bytes(substream),
  snd_pcm_lib_buffer_bytes(substream) /
  snd_pcm_lib_period_bytes(substream),
  substream->runtime->periods,
  chip->fmt_size);
#endif
 return 0;
}

static int snd_pcsp_trigger(struct snd_pcm_substream *substream, int cmd)
{
 struct snd_pcsp *chip = snd_pcm_substream_chip(substream);
#if PCSP_DEBUG
 dev_dbg(chip->card->dev, "PCSP: trigger called\n");
#endif
 switch (cmd) {
 case SNDRV_PCM_TRIGGER_START:
 case SNDRV_PCM_TRIGGER_RESUME:
  return pcsp_start_playing(chip);
 case SNDRV_PCM_TRIGGER_STOP:
 case SNDRV_PCM_TRIGGER_SUSPEND:
  pcsp_stop_playing(chip);
  break;
 default:
  return -EINVAL;
 }
 return 0;
}

static snd_pcm_uframes_t snd_pcsp_playback_pointer(struct snd_pcm_substream
         *substream)
{
 struct snd_pcsp *chip = snd_pcm_substream_chip(substream);
 unsigned int pos;
 spin_lock(&chip->substream_lock);
 pos = chip->playback_ptr;
 spin_unlock(&chip->substream_lock);
 return bytes_to_frames(substream->runtime, pos);
}

static const struct snd_pcm_hardware snd_pcsp_playback = {
 .info = (SNDRV_PCM_INFO_INTERLEAVED |
   SNDRV_PCM_INFO_HALF_DUPLEX |
   SNDRV_PCM_INFO_MMAP | SNDRV_PCM_INFO_MMAP_VALID),
 .formats = (SNDRV_PCM_FMTBIT_U8
#if DMIX_WANTS_S16
      | SNDRV_PCM_FMTBIT_S16_LE
#endif
     ),
 .rates = SNDRV_PCM_RATE_KNOT,
 .rate_min = PCSP_DEFAULT_SRATE,
 .rate_max = PCSP_DEFAULT_SRATE,
 .channels_min = 1,
 .channels_max = 1,
 .buffer_bytes_max = PCSP_BUFFER_SIZE,
 .period_bytes_min = 64,
 .period_bytes_max = PCSP_MAX_PERIOD_SIZE,
 .periods_min = 2,
 .periods_max = PCSP_MAX_PERIODS,
 .fifo_size = 0,
};

static int snd_pcsp_playback_open(struct snd_pcm_substream *substream)
{
 struct snd_pcsp *chip = snd_pcm_substream_chip(substream);
 struct snd_pcm_runtime *runtime = substream->runtime;
#if PCSP_DEBUG
 dev_dbg(chip->card->dev, "PCSP: open called\n");
#endif
 if (atomic_read(&chip->timer_active)) {
  dev_err(chip->card->dev, "PCSP: still active!!\n");
  return -EBUSY;
 }
 runtime->hw = snd_pcsp_playback;
 chip->playback_substream = substream;
 return 0;
}

static const struct snd_pcm_ops snd_pcsp_playback_ops = {
 .open = snd_pcsp_playback_open,
 .close = snd_pcsp_playback_close,
 .hw_params = snd_pcsp_playback_hw_params,
 .hw_free = snd_pcsp_playback_hw_free,
 .prepare = snd_pcsp_playback_prepare,
 .trigger = snd_pcsp_trigger,
 .pointer = snd_pcsp_playback_pointer,
};

int snd_pcsp_new_pcm(struct snd_pcsp *chip)
{
 int err;

 err = snd_pcm_new(chip->card, "pcspeaker", 0, 1, 0, &chip->pcm);
 if (err < 0)
  return err;

 snd_pcm_set_ops(chip->pcm, SNDRV_PCM_STREAM_PLAYBACK,
   &snd_pcsp_playback_ops);

 chip->pcm->private_data = chip;
 chip->pcm->info_flags = SNDRV_PCM_INFO_HALF_DUPLEX;
 strscpy(chip->pcm->name, "pcsp");

 snd_pcm_set_managed_buffer_all(chip->pcm,
           SNDRV_DMA_TYPE_CONTINUOUS,
           NULL,
           PCSP_BUFFER_SIZE,
           PCSP_BUFFER_SIZE);

 return 0;
}