pcsp_lib.c

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/*
 * 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 <sound/pcm.h>
#include <asm/io.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 tasklet
 * This avoids spinlock messes and long-running irq contexts
 */
static void pcsp_call_pcm_elapsed(unsigned long priv)
{
    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_TASKLET(pcsp_pcm_tasklet, pcsp_call_pcm_elapsed, 0);

/* 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
        printk(KERN_INFO "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;
    }
    spin_unlock_irqrestore(&chip->substream_lock, flags);

    if (periods_elapsed)
        tasklet_schedule(&pcsp_pcm_tasklet);
}

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) {
        printk(KERN_WARNING "PCSP: unexpected stop\n");
        return HRTIMER_NORESTART;
    }

    if (pointer_update)
        pcsp_pointer_update(chip);

    hrtimer_forward(handle, hrtimer_get_expires(handle), ns_to_ktime(ns));

    return HRTIMER_RESTART;
}

static int pcsp_start_playing(struct snd_pcsp *chip)
{
#if PCSP_DEBUG
    printk(KERN_INFO "PCSP: start_playing called\n");
#endif
    if (atomic_read(&chip->timer_active)) {
        printk(KERN_ERR "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, ktime_set(0, 0), HRTIMER_MODE_REL);
    return 0;
}

static void pcsp_stop_playing(struct snd_pcsp *chip)
{
#if PCSP_DEBUG
    printk(KERN_INFO "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);
    tasklet_kill(&pcsp_pcm_tasklet);
}

static int snd_pcsp_playback_close(struct snd_pcm_substream *substream)
{
    struct snd_pcsp *chip = snd_pcm_substream_chip(substream);
#if PCSP_DEBUG
    printk(KERN_INFO "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);
    int err;
    pcsp_sync_stop(chip);
    err = snd_pcm_lib_malloc_pages(substream,
                      params_buffer_bytes(hw_params));
    if (err < 0)
        return err;
    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
    printk(KERN_INFO "PCSP: hw_free called\n");
#endif
    pcsp_sync_stop(chip);
    return snd_pcm_lib_free_pages(substream);
}

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
    printk(KERN_INFO "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
    printk(KERN_INFO "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 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
    printk(KERN_INFO "PCSP: open called\n");
#endif
    if (atomic_read(&chip->timer_active)) {
        printk(KERN_ERR "PCSP: still active!!\n");
        return -EBUSY;
    }
    runtime->hw = snd_pcsp_playback;
    chip->playback_substream = substream;
    return 0;
}

static struct snd_pcm_ops snd_pcsp_playback_ops = {
    .open = snd_pcsp_playback_open,
    .close = snd_pcsp_playback_close,
    .ioctl = snd_pcm_lib_ioctl,
    .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 __devinit 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;
    strcpy(chip->pcm->name, "pcsp");

    snd_pcm_lib_preallocate_pages_for_all(chip->pcm,
                          SNDRV_DMA_TYPE_CONTINUOUS,
                          snd_dma_continuous_data
                          (GFP_KERNEL), PCSP_BUFFER_SIZE,
                          PCSP_BUFFER_SIZE);

    return 0;
}