sound/isa/sb/sb8_main.c

Source file repositories/reference/linux-study-clean/sound/isa/sb/sb8_main.c

File Facts

System
Linux kernel
Corpus path
sound/isa/sb/sb8_main.c
Extension
.c
Size
16629 bytes
Lines
581
Domain
Driver Families
Bucket
sound/isa
Inferred role
Driver Families: exported/initcall integration point
Status
integration implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

if (err >= 0 && den) {
			params->rate_num = num;
			params->rate_den = den;
		}
		return err;
	}
	return 0;
}

static int snd_sb8_hw_constraint_channels_rate(struct snd_pcm_hw_params *params,
					       struct snd_pcm_hw_rule *rule)
{
	struct snd_interval *r = hw_param_interval(params, SNDRV_PCM_HW_PARAM_RATE);
	if (r->min > SB8_RATE(22050) || r->max <= SB8_RATE(11025)) {
		struct snd_interval t = { .min = 1, .max = 1 };
		return snd_interval_refine(hw_param_interval(params, SNDRV_PCM_HW_PARAM_CHANNELS), &t);
	}
	return 0;
}

static int snd_sb8_playback_prepare(struct snd_pcm_substream *substream)
{
	struct snd_sb *chip = snd_pcm_substream_chip(substream);
	struct snd_pcm_runtime *runtime = substream->runtime;
	unsigned int mixreg, rate, size, count;
	unsigned char format;
	unsigned char stereo = runtime->channels > 1;
	int dma;

	rate = runtime->rate;
	switch (chip->hardware) {
	case SB_HW_JAZZ16:
		if (runtime->format == SNDRV_PCM_FORMAT_S16_LE) {
			if (chip->mode & SB_MODE_CAPTURE_16)
				return -EBUSY;
			else
				chip->mode |= SB_MODE_PLAYBACK_16;
		}
		chip->playback_format = SB_DSP_LO_OUTPUT_AUTO;
		break;
	case SB_HW_PRO:
		if (runtime->channels > 1) {
			if (snd_BUG_ON(rate != SB8_RATE(11025) &&
				       rate != SB8_RATE(22050)))
				return -EINVAL;
			chip->playback_format = SB_DSP_HI_OUTPUT_AUTO;
			break;
		}
		fallthrough;
	case SB_HW_201:
		if (rate > 23000) {
			chip->playback_format = SB_DSP_HI_OUTPUT_AUTO;
			break;
		}
		fallthrough;
	case SB_HW_20:
		chip->playback_format = SB_DSP_LO_OUTPUT_AUTO;
		break;
	case SB_HW_10:
		chip->playback_format = SB_DSP_OUTPUT;
		break;
	default:
		return -EINVAL;
	}
	if (chip->mode & SB_MODE_PLAYBACK_16) {
		format = stereo ? SB_DSP_STEREO_16BIT : SB_DSP_MONO_16BIT;
		dma = chip->dma16;
	} else {
		format = stereo ? SB_DSP_STEREO_8BIT : SB_DSP_MONO_8BIT;
		chip->mode |= SB_MODE_PLAYBACK_8;
		dma = chip->dma8;
	}
	size = chip->p_dma_size = snd_pcm_lib_buffer_bytes(substream);
	count = chip->p_period_size = snd_pcm_lib_period_bytes(substream);
	scoped_guard(spinlock_irqsave, &chip->reg_lock) {
		snd_sbdsp_command(chip, SB_DSP_SPEAKER_ON);
		if (chip->hardware == SB_HW_JAZZ16)
			snd_sbdsp_command(chip, format);
		else if (stereo) {
			/* set playback stereo mode */
			scoped_guard(spinlock, &chip->mixer_lock) {
				mixreg = snd_sbmixer_read(chip, SB_DSP_STEREO_SW);
				snd_sbmixer_write(chip, SB_DSP_STEREO_SW, mixreg | 0x02);
			}

			/* Soundblaster hardware programming reference guide, 3-23 */
			snd_sbdsp_command(chip, SB_DSP_DMA8_EXIT);
			runtime->dma_area[0] = 0x80;
			snd_dma_program(dma, runtime->dma_addr, 1, DMA_MODE_WRITE);
			/* force interrupt */

Annotation

Implementation Notes