root/sound/soc/au1x/dma.c
// SPDX-License-Identifier: GPL-2.0-only
/*
 * Au1000/Au1500/Au1100 Audio DMA support.
 *
 * (c) 2011 Manuel Lauss <manuel.lauss@googlemail.com>
 *
 * copied almost verbatim from the old ALSA driver, written by
 *                      Charles Eidsness <charles@cooper-street.com>
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/dma-mapping.h>
#include <sound/core.h>
#include <sound/pcm.h>
#include <sound/pcm_params.h>
#include <sound/soc.h>
#include <asm/mach-au1x00/au1000.h>
#include <asm/mach-au1x00/au1000_dma.h>

#include "psc.h"

#define DRV_NAME "au1x_dma"

struct pcm_period {
        u32 start;
        u32 relative_end;       /* relative to start of buffer */
        struct pcm_period *next;
};

struct audio_stream {
        struct snd_pcm_substream *substream;
        int dma;
        struct pcm_period *buffer;
        unsigned int period_size;
        unsigned int periods;
};

struct alchemy_pcm_ctx {
        struct audio_stream stream[2];  /* playback & capture */
};

static void au1000_release_dma_link(struct audio_stream *stream)
{
        struct pcm_period *pointer;
        struct pcm_period *pointer_next;

        stream->period_size = 0;
        stream->periods = 0;
        pointer = stream->buffer;
        if (!pointer)
                return;
        do {
                pointer_next = pointer->next;
                kfree(pointer);
                pointer = pointer_next;
        } while (pointer != stream->buffer);
        stream->buffer = NULL;
}

static int au1000_setup_dma_link(struct audio_stream *stream,
                                 unsigned int period_bytes,
                                 unsigned int periods)
{
        struct snd_pcm_substream *substream = stream->substream;
        struct snd_pcm_runtime *runtime = substream->runtime;
        struct pcm_period *pointer;
        unsigned long dma_start;
        int i;

        dma_start = virt_to_phys(runtime->dma_area);

        if (stream->period_size == period_bytes &&
            stream->periods == periods)
                return 0; /* not changed */

        au1000_release_dma_link(stream);

        stream->period_size = period_bytes;
        stream->periods = periods;

        stream->buffer = kmalloc_obj(struct pcm_period);
        if (!stream->buffer)
                return -ENOMEM;
        pointer = stream->buffer;
        for (i = 0; i < periods; i++) {
                pointer->start = (u32)(dma_start + (i * period_bytes));
                pointer->relative_end = (u32) (((i+1) * period_bytes) - 0x1);
                if (i < periods - 1) {
                        pointer->next = kmalloc_obj(struct pcm_period);
                        if (!pointer->next) {
                                au1000_release_dma_link(stream);
                                return -ENOMEM;
                        }
                        pointer = pointer->next;
                }
        }
        pointer->next = stream->buffer;
        return 0;
}

static void au1000_dma_stop(struct audio_stream *stream)
{
        if (stream->buffer)
                disable_dma(stream->dma);
}

static void au1000_dma_start(struct audio_stream *stream)
{
        if (!stream->buffer)
                return;

        init_dma(stream->dma);
        if (get_dma_active_buffer(stream->dma) == 0) {
                clear_dma_done0(stream->dma);
                set_dma_addr0(stream->dma, stream->buffer->start);
                set_dma_count0(stream->dma, stream->period_size >> 1);
                set_dma_addr1(stream->dma, stream->buffer->next->start);
                set_dma_count1(stream->dma, stream->period_size >> 1);
        } else {
                clear_dma_done1(stream->dma);
                set_dma_addr1(stream->dma, stream->buffer->start);
                set_dma_count1(stream->dma, stream->period_size >> 1);
                set_dma_addr0(stream->dma, stream->buffer->next->start);
                set_dma_count0(stream->dma, stream->period_size >> 1);
        }
        enable_dma_buffers(stream->dma);
        start_dma(stream->dma);
}

static irqreturn_t au1000_dma_interrupt(int irq, void *ptr)
{
        struct audio_stream *stream = (struct audio_stream *)ptr;
        struct snd_pcm_substream *substream = stream->substream;

        switch (get_dma_buffer_done(stream->dma)) {
        case DMA_D0:
                stream->buffer = stream->buffer->next;
                clear_dma_done0(stream->dma);
                set_dma_addr0(stream->dma, stream->buffer->next->start);
                set_dma_count0(stream->dma, stream->period_size >> 1);
                enable_dma_buffer0(stream->dma);
                break;
        case DMA_D1:
                stream->buffer = stream->buffer->next;
                clear_dma_done1(stream->dma);
                set_dma_addr1(stream->dma, stream->buffer->next->start);
                set_dma_count1(stream->dma, stream->period_size >> 1);
                enable_dma_buffer1(stream->dma);
                break;
        case (DMA_D0 | DMA_D1):
                pr_debug("DMA %d missed interrupt.\n", stream->dma);
                au1000_dma_stop(stream);
                au1000_dma_start(stream);
                break;
        case (~DMA_D0 & ~DMA_D1):
                pr_debug("DMA %d empty irq.\n", stream->dma);
        }
        snd_pcm_period_elapsed(substream);
        return IRQ_HANDLED;
}

static const struct snd_pcm_hardware alchemy_pcm_hardware = {
        .info             = SNDRV_PCM_INFO_MMAP | SNDRV_PCM_INFO_MMAP_VALID |
                            SNDRV_PCM_INFO_INTERLEAVED | SNDRV_PCM_INFO_BATCH,
        .period_bytes_min = 1024,
        .period_bytes_max = 16 * 1024 - 1,
        .periods_min      = 4,
        .periods_max      = 255,
        .buffer_bytes_max = 128 * 1024,
        .fifo_size        = 16,
};

static inline struct alchemy_pcm_ctx *ss_to_ctx(struct snd_pcm_substream *ss,
                                                struct snd_soc_component *component)
{
        return snd_soc_component_get_drvdata(component);
}

static inline struct audio_stream *ss_to_as(struct snd_pcm_substream *ss,
                                            struct snd_soc_component *component)
{
        struct alchemy_pcm_ctx *ctx = ss_to_ctx(ss, component);
        return &(ctx->stream[ss->stream]);
}

static int alchemy_pcm_open(struct snd_soc_component *component,
                            struct snd_pcm_substream *substream)
{
        struct alchemy_pcm_ctx *ctx = ss_to_ctx(substream, component);
        struct snd_soc_pcm_runtime *rtd = snd_soc_substream_to_rtd(substream);
        int *dmaids, s = substream->stream;
        char *name;

        dmaids = snd_soc_dai_get_dma_data(snd_soc_rtd_to_cpu(rtd, 0), substream);
        if (!dmaids)
                return -ENODEV; /* whoa, has ordering changed? */

        /* DMA setup */
        name = (s == SNDRV_PCM_STREAM_PLAYBACK) ? "audio-tx" : "audio-rx";
        ctx->stream[s].dma = request_au1000_dma(dmaids[s], name,
                                        au1000_dma_interrupt, 0,
                                        &ctx->stream[s]);
        set_dma_mode(ctx->stream[s].dma,
                     get_dma_mode(ctx->stream[s].dma) & ~DMA_NC);

        ctx->stream[s].substream = substream;
        ctx->stream[s].buffer = NULL;
        snd_soc_set_runtime_hwparams(substream, &alchemy_pcm_hardware);

        return 0;
}

static int alchemy_pcm_close(struct snd_soc_component *component,
                             struct snd_pcm_substream *substream)
{
        struct alchemy_pcm_ctx *ctx = ss_to_ctx(substream, component);
        int stype = substream->stream;

        ctx->stream[stype].substream = NULL;
        free_au1000_dma(ctx->stream[stype].dma);

        return 0;
}

static int alchemy_pcm_hw_params(struct snd_soc_component *component,
                                 struct snd_pcm_substream *substream,
                                 struct snd_pcm_hw_params *hw_params)
{
        struct audio_stream *stream = ss_to_as(substream, component);

        return au1000_setup_dma_link(stream,
                                     params_period_bytes(hw_params),
                                     params_periods(hw_params));
}

static int alchemy_pcm_hw_free(struct snd_soc_component *component,
                               struct snd_pcm_substream *substream)
{
        struct audio_stream *stream = ss_to_as(substream, component);
        au1000_release_dma_link(stream);
        return 0;
}

static int alchemy_pcm_trigger(struct snd_soc_component *component,
                               struct snd_pcm_substream *substream, int cmd)
{
        struct audio_stream *stream = ss_to_as(substream, component);
        int err = 0;

        switch (cmd) {
        case SNDRV_PCM_TRIGGER_START:
                au1000_dma_start(stream);
                break;
        case SNDRV_PCM_TRIGGER_STOP:
                au1000_dma_stop(stream);
                break;
        default:
                err = -EINVAL;
                break;
        }
        return err;
}

static snd_pcm_uframes_t alchemy_pcm_pointer(struct snd_soc_component *component,
                                             struct snd_pcm_substream *ss)
{
        struct audio_stream *stream = ss_to_as(ss, component);
        long location;

        location = get_dma_residue(stream->dma);
        location = stream->buffer->relative_end - location;
        if (location == -1)
                location = 0;
        return bytes_to_frames(ss->runtime, location);
}

static int alchemy_pcm_new(struct snd_soc_component *component,
                           struct snd_soc_pcm_runtime *rtd)
{
        struct snd_pcm *pcm = rtd->pcm;

        snd_pcm_set_managed_buffer_all(pcm, SNDRV_DMA_TYPE_CONTINUOUS,
                                       NULL, 65536, (4096 * 1024) - 1);

        return 0;
}

static const struct snd_soc_component_driver alchemy_pcm_soc_component = {
        .name           = DRV_NAME,
        .open           = alchemy_pcm_open,
        .close          = alchemy_pcm_close,
        .hw_params      = alchemy_pcm_hw_params,
        .hw_free        = alchemy_pcm_hw_free,
        .trigger        = alchemy_pcm_trigger,
        .pointer        = alchemy_pcm_pointer,
        .pcm_construct  = alchemy_pcm_new,
};

static int alchemy_pcm_drvprobe(struct platform_device *pdev)
{
        struct alchemy_pcm_ctx *ctx;

        ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL);
        if (!ctx)
                return -ENOMEM;

        platform_set_drvdata(pdev, ctx);

        return devm_snd_soc_register_component(&pdev->dev,
                                        &alchemy_pcm_soc_component, NULL, 0);
}

static struct platform_driver alchemy_pcmdma_driver = {
        .driver = {
                .name   = "alchemy-pcm-dma",
        },
        .probe          = alchemy_pcm_drvprobe,
};

module_platform_driver(alchemy_pcmdma_driver);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Au1000/Au1500/Au1100 Audio DMA driver");
MODULE_AUTHOR("Manuel Lauss");