sound/drivers/pcsp/pcsp_lib.c - linux - Git at Google

 // 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/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 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, 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);
 	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
 	printk(KERN_INFO "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
 	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 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
 	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 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;
 	strcpy(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;
 }
	// 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/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 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, 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);
	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
	printk(KERN_INFO "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
	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 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
	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 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;
	strcpy(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;
	}