root/sound/firewire/tascam/amdtp-tascam.c
// SPDX-License-Identifier: GPL-2.0-only
/*
 * amdtp-tascam.c - a part of driver for TASCAM FireWire series
 *
 * Copyright (c) 2015 Takashi Sakamoto
 */

#include <sound/pcm.h>
#include "tascam.h"

#define AMDTP_FMT_TSCM_TX       0x1e
#define AMDTP_FMT_TSCM_RX       0x3e

struct amdtp_tscm {
        unsigned int pcm_channels;
};

int amdtp_tscm_set_parameters(struct amdtp_stream *s, unsigned int rate)
{
        struct amdtp_tscm *p = s->protocol;
        unsigned int data_channels;

        if (amdtp_stream_running(s))
                return -EBUSY;

        data_channels = p->pcm_channels;

        /* Packets in in-stream have extra 2 data channels. */
        if (s->direction == AMDTP_IN_STREAM)
                data_channels += 2;

        return amdtp_stream_set_parameters(s, rate, data_channels, 1);
}

static void write_pcm_s32(struct amdtp_stream *s, struct snd_pcm_substream *pcm,
                          __be32 *buffer, unsigned int frames,
                          unsigned int pcm_frames)
{
        struct amdtp_tscm *p = s->protocol;
        unsigned int channels = p->pcm_channels;
        struct snd_pcm_runtime *runtime = pcm->runtime;
        unsigned int pcm_buffer_pointer;
        int remaining_frames;
        const u32 *src;
        int i, c;

        pcm_buffer_pointer = s->pcm_buffer_pointer + pcm_frames;
        pcm_buffer_pointer %= runtime->buffer_size;

        src = (void *)runtime->dma_area +
                                frames_to_bytes(runtime, pcm_buffer_pointer);
        remaining_frames = runtime->buffer_size - pcm_buffer_pointer;

        for (i = 0; i < frames; ++i) {
                for (c = 0; c < channels; ++c) {
                        buffer[c] = cpu_to_be32(*src);
                        src++;
                }
                buffer += s->data_block_quadlets;
                if (--remaining_frames == 0)
                        src = (void *)runtime->dma_area;
        }
}

static void read_pcm_s32(struct amdtp_stream *s, struct snd_pcm_substream *pcm,
                         __be32 *buffer, unsigned int frames,
                         unsigned int pcm_frames)
{
        struct amdtp_tscm *p = s->protocol;
        unsigned int channels = p->pcm_channels;
        struct snd_pcm_runtime *runtime = pcm->runtime;
        unsigned int pcm_buffer_pointer;
        int remaining_frames;
        u32 *dst;
        int i, c;

        pcm_buffer_pointer = s->pcm_buffer_pointer + pcm_frames;
        pcm_buffer_pointer %= runtime->buffer_size;

        dst  = (void *)runtime->dma_area +
                                frames_to_bytes(runtime, pcm_buffer_pointer);
        remaining_frames = runtime->buffer_size - pcm_buffer_pointer;

        /* The first data channel is for event counter. */
        buffer += 1;

        for (i = 0; i < frames; ++i) {
                for (c = 0; c < channels; ++c) {
                        *dst = be32_to_cpu(buffer[c]);
                        dst++;
                }
                buffer += s->data_block_quadlets;
                if (--remaining_frames == 0)
                        dst = (void *)runtime->dma_area;
        }
}

static void write_pcm_silence(struct amdtp_stream *s, __be32 *buffer,
                              unsigned int data_blocks)
{
        struct amdtp_tscm *p = s->protocol;
        unsigned int channels, i, c;

        channels = p->pcm_channels;

        for (i = 0; i < data_blocks; ++i) {
                for (c = 0; c < channels; ++c)
                        buffer[c] = 0x00000000;
                buffer += s->data_block_quadlets;
        }
}

int amdtp_tscm_add_pcm_hw_constraints(struct amdtp_stream *s,
                                      struct snd_pcm_runtime *runtime)
{
        int err;

        /*
         * Our implementation allows this protocol to deliver 24 bit sample in
         * 32bit data channel.
         */
        err = snd_pcm_hw_constraint_msbits(runtime, 0, 32, 24);
        if (err < 0)
                return err;

        return amdtp_stream_add_pcm_hw_constraints(s, runtime);
}

static void read_status_messages(struct amdtp_stream *s,
                                 __be32 *buffer, unsigned int data_blocks)
{
        struct snd_tscm *tscm = container_of(s, struct snd_tscm, tx_stream);
        bool used = READ_ONCE(tscm->hwdep->used);
        int i;

        for (i = 0; i < data_blocks; i++) {
                unsigned int index;
                __be32 before;
                __be32 after;

                index = be32_to_cpu(buffer[0]) % SNDRV_FIREWIRE_TASCAM_STATE_COUNT;
                before = tscm->state[index];
                after = buffer[s->data_block_quadlets - 1];

                if (used && index > 4 && index < 16) {
                        __be32 mask;

                        if (index == 5)
                                mask = cpu_to_be32(~0x0000ffff);
                        else if (index == 6)
                                mask = cpu_to_be32(~0x0000ffff);
                        else if (index == 8)
                                mask = cpu_to_be32(~0x000f0f00);
                        else
                                mask = cpu_to_be32(~0x00000000);

                        if ((before ^ after) & mask) {
                                struct snd_firewire_tascam_change *entry =
                                                &tscm->queue[tscm->push_pos];

                                scoped_guard(spinlock_irqsave, &tscm->lock) {
                                        entry->index = index;
                                        entry->before = before;
                                        entry->after = after;
                                        if (++tscm->push_pos >= SND_TSCM_QUEUE_COUNT)
                                                tscm->push_pos = 0;
                                }

                                wake_up(&tscm->hwdep_wait);
                        }
                }

                tscm->state[index] = after;
                buffer += s->data_block_quadlets;
        }
}

static void process_ir_ctx_payloads(struct amdtp_stream *s, const struct pkt_desc *desc,
                                    unsigned int count, struct snd_pcm_substream *pcm)
{
        unsigned int pcm_frames = 0;
        int i;

        for (i = 0; i < count; ++i) {
                __be32 *buf = desc->ctx_payload;
                unsigned int data_blocks = desc->data_blocks;

                if (pcm) {
                        read_pcm_s32(s, pcm, buf, data_blocks, pcm_frames);
                        pcm_frames += data_blocks;
                }

                read_status_messages(s, buf, data_blocks);

                desc = amdtp_stream_next_packet_desc(s, desc);
        }
}

static void process_it_ctx_payloads(struct amdtp_stream *s, const struct pkt_desc *desc,
                                    unsigned int count, struct snd_pcm_substream *pcm)
{
        unsigned int pcm_frames = 0;
        int i;

        for (i = 0; i < count; ++i) {
                __be32 *buf = desc->ctx_payload;
                unsigned int data_blocks = desc->data_blocks;

                if (pcm) {
                        write_pcm_s32(s, pcm, buf, data_blocks, pcm_frames);
                        pcm_frames += data_blocks;
                } else {
                        write_pcm_silence(s, buf, data_blocks);
                }

                desc = amdtp_stream_next_packet_desc(s, desc);
        }
}

int amdtp_tscm_init(struct amdtp_stream *s, struct fw_unit *unit,
                    enum amdtp_stream_direction dir, unsigned int pcm_channels)
{
        amdtp_stream_process_ctx_payloads_t process_ctx_payloads;
        unsigned int flags = CIP_NONBLOCKING | CIP_SKIP_DBC_ZERO_CHECK | CIP_UNAWARE_SYT;
        struct amdtp_tscm *p;
        unsigned int fmt;
        int err;

        if (dir == AMDTP_IN_STREAM) {
                fmt = AMDTP_FMT_TSCM_TX;
                process_ctx_payloads = process_ir_ctx_payloads;
        } else {
                fmt = AMDTP_FMT_TSCM_RX;
                process_ctx_payloads = process_it_ctx_payloads;
        }

        err = amdtp_stream_init(s, unit, dir, flags, fmt,
                        process_ctx_payloads, sizeof(struct amdtp_tscm));
        if (err < 0)
                return err;

        if (dir == AMDTP_OUT_STREAM) {
                // Use fixed value for FDF field.
                s->ctx_data.rx.fdf = 0x00;
        }

        /* This protocol uses fixed number of data channels for PCM samples. */
        p = s->protocol;
        p->pcm_channels = pcm_channels;

        return 0;
}