// SPDX-License-Identifier: GPL-2.0-only
// Copyright (c) 2025 Šerif Rami <ramiserifpersia@gmail.com>

#include "us144mkii.h"

/**
 * fpo_init_pattern() - Generates a packet distribution pattern.
 * @size: The number of elements in the pattern array (e.g., 8).
 * @pattern_array: Pointer to the array to be populated.
 * @initial_value: The base value to initialize each element with.
 * @target_sum: The desired sum of all elements in the final array.
 *
 * This function initializes an array with a base value and then iteratively
 * adjusts the elements to match a target sum, distributing the difference
 * as evenly as possible.
 */
static void fpo_init_pattern(unsigned int size, unsigned int *pattern_array,
        unsigned int initial_value, int target_sum)
{
        int diff, i;

        if (!size)
                return;

        for (i = 0; i < size; ++i)
                pattern_array[i] = initial_value;

        diff = target_sum - (size * initial_value);
        for (i = 0; i < abs(diff); ++i) {
                if (diff > 0)
                        pattern_array[i]++;
                else
                        pattern_array[i]--;
        }
}

const struct snd_pcm_hardware tascam_pcm_hw = {
        .info = (SNDRV_PCM_INFO_MMAP | SNDRV_PCM_INFO_INTERLEAVED |
                 SNDRV_PCM_INFO_BLOCK_TRANSFER | SNDRV_PCM_INFO_MMAP_VALID |
                 SNDRV_PCM_INFO_PAUSE | SNDRV_PCM_INFO_RESUME),
        .formats = SNDRV_PCM_FMTBIT_S24_3LE,
        .rates = (SNDRV_PCM_RATE_44100 | SNDRV_PCM_RATE_48000 |
                  SNDRV_PCM_RATE_88200 | SNDRV_PCM_RATE_96000),
        .rate_min = 44100,
        .rate_max = 96000,
        .channels_min = NUM_CHANNELS,
        .channels_max = NUM_CHANNELS,
        .buffer_bytes_max = 1024 * 1024,
        .period_bytes_min = 48 * BYTES_PER_FRAME,
        .period_bytes_max = 1024 * BYTES_PER_FRAME,
        .periods_min = 2,
        .periods_max = 1024,
};

void process_playback_routing_us144mkii(struct tascam_card *tascam,
                                        const u8 *src_buffer, u8 *dst_buffer,
                                        size_t frames)
{
        size_t f;
        const u8 *src_12, *src_34;
        u8 *dst_line, *dst_digital;

        for (f = 0; f < frames; ++f) {
                src_12 = src_buffer + f * BYTES_PER_FRAME;
                src_34 = src_12 + (2 * BYTES_PER_SAMPLE);
                dst_line = dst_buffer + f * BYTES_PER_FRAME;
                dst_digital = dst_line + (2 * BYTES_PER_SAMPLE);

                /* LINE OUTPUTS (ch1/2 on device) */
                if (tascam->line_out_source == 0) /* "ch1 and ch2" */
                        memcpy(dst_line, src_12, 2 * BYTES_PER_SAMPLE);
                else /* "ch3 and ch4" */
                        memcpy(dst_line, src_34, 2 * BYTES_PER_SAMPLE);

                /* DIGITAL OUTPUTS (ch3/4 on device) */
                if (tascam->digital_out_source == 0) /* "ch1 and ch2" */
                        memcpy(dst_digital, src_12, 2 * BYTES_PER_SAMPLE);
                else /* "ch3 and ch4" */
                        memcpy(dst_digital, src_34, 2 * BYTES_PER_SAMPLE);
        }
}

void process_capture_routing_us144mkii(struct tascam_card *tascam,
                                       const s32 *decoded_block,
                                       s32 *routed_block)
{
        int f;
        const s32 *src_frame;
        s32 *dst_frame;

        for (f = 0; f < FRAMES_PER_DECODE_BLOCK; f++) {
                src_frame = decoded_block + (f * DECODED_CHANNELS_PER_FRAME);
                dst_frame = routed_block + (f * DECODED_CHANNELS_PER_FRAME);

                /* ch1 and ch2 Source */
                if (tascam->capture_12_source == 0) { /* analog inputs */
                        dst_frame[0] = src_frame[0]; /* Analog L */
                        dst_frame[1] = src_frame[1]; /* Analog R */
                } else { /* digital inputs */
                        dst_frame[0] = src_frame[2]; /* Digital L */
                        dst_frame[1] = src_frame[3]; /* Digital R */
                }

                /* ch3 and ch4 Source */
                if (tascam->capture_34_source == 0) { /* analog inputs */
                        dst_frame[2] = src_frame[0]; /* Analog L (Duplicate) */
                        dst_frame[3] = src_frame[1]; /* Analog R (Duplicate) */
                } else { /* digital inputs */
                        dst_frame[2] = src_frame[2]; /* Digital L */
                        dst_frame[3] = src_frame[3]; /* Digital R */
                }
        }
}

int us144mkii_configure_device_for_rate(struct tascam_card *tascam, int rate)
{
        struct usb_device *dev = tascam->dev;
        u16 rate_vendor_wValue;
        int err = 0;
        const u8 *current_payload_src;

        static const u8 payload_44100[] = { 0x44, 0xac, 0x00 };
        static const u8 payload_48000[] = { 0x80, 0xbb, 0x00 };
        static const u8 payload_88200[] = { 0x88, 0x58, 0x01 };
        static const u8 payload_96000[] = { 0x00, 0x77, 0x01 };

        switch (rate) {
        case 44100:
                current_payload_src = payload_44100;
                rate_vendor_wValue = REG_ADDR_RATE_44100;
                break;
        case 48000:
                current_payload_src = payload_48000;
                rate_vendor_wValue = REG_ADDR_RATE_48000;
                break;
        case 88200:
                current_payload_src = payload_88200;
                rate_vendor_wValue = REG_ADDR_RATE_88200;
                break;
        case 96000:
                current_payload_src = payload_96000;
                rate_vendor_wValue = REG_ADDR_RATE_96000;
                break;
        default:
                dev_err(&dev->dev,
                        "Unsupported sample rate %d for configuration\n", rate);
                return -EINVAL;
        }

        u8 *rate_payload_buf __free(kfree) =
                kmemdup(current_payload_src, 3, GFP_KERNEL);
        if (!rate_payload_buf)
                return -ENOMEM;

        dev_info(&dev->dev, "Configuring device for %d Hz\n", rate);

        err = usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
                              VENDOR_REQ_MODE_CONTROL, RT_H2D_VENDOR_DEV,
                              MODE_VAL_CONFIG, 0x0000, NULL, 0,
                              USB_CTRL_TIMEOUT_MS);
        if (err < 0)
                goto fail;
        err = usb_control_msg(dev, usb_sndctrlpipe(dev, 0), UAC_SET_CUR,
                              RT_H2D_CLASS_EP, UAC_SAMPLING_FREQ_CONTROL,
                              EP_AUDIO_IN, rate_payload_buf, 3,
                              USB_CTRL_TIMEOUT_MS);
        if (err < 0)
                goto fail;
        err = usb_control_msg(dev, usb_sndctrlpipe(dev, 0), UAC_SET_CUR,
                              RT_H2D_CLASS_EP, UAC_SAMPLING_FREQ_CONTROL,
                              EP_AUDIO_OUT, rate_payload_buf, 3,
                              USB_CTRL_TIMEOUT_MS);
        if (err < 0)
                goto fail;
        err = usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
                              VENDOR_REQ_REGISTER_WRITE, RT_H2D_VENDOR_DEV,
                              REG_ADDR_UNKNOWN_0D, REG_VAL_ENABLE, NULL, 0,
                              USB_CTRL_TIMEOUT_MS);
        if (err < 0)
                goto fail;
        err = usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
                              VENDOR_REQ_REGISTER_WRITE, RT_H2D_VENDOR_DEV,
                              REG_ADDR_UNKNOWN_0E, REG_VAL_ENABLE, NULL, 0,
                              USB_CTRL_TIMEOUT_MS);
        if (err < 0)
                goto fail;
        err = usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
                              VENDOR_REQ_REGISTER_WRITE, RT_H2D_VENDOR_DEV,
                              REG_ADDR_UNKNOWN_0F, REG_VAL_ENABLE, NULL, 0,
                              USB_CTRL_TIMEOUT_MS);
        if (err < 0)
                goto fail;
        err = usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
                              VENDOR_REQ_REGISTER_WRITE, RT_H2D_VENDOR_DEV,
                              rate_vendor_wValue, REG_VAL_ENABLE, NULL, 0,
                              USB_CTRL_TIMEOUT_MS);
        if (err < 0)
                goto fail;
        err = usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
                              VENDOR_REQ_REGISTER_WRITE, RT_H2D_VENDOR_DEV,
                              REG_ADDR_UNKNOWN_11, REG_VAL_ENABLE, NULL, 0,
                              USB_CTRL_TIMEOUT_MS);
        if (err < 0)
                goto fail;
        err = usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
                              VENDOR_REQ_MODE_CONTROL, RT_H2D_VENDOR_DEV,
                              MODE_VAL_STREAM_START, 0x0000, NULL, 0,
                              USB_CTRL_TIMEOUT_MS);
        if (err < 0)
                goto fail;
        return 0;

fail:
        dev_err(&dev->dev,
                "Device configuration failed at rate %d with error %d\n", rate,
                err);
        return err;
}

int tascam_pcm_hw_params(struct snd_pcm_substream *substream,
                                         struct snd_pcm_hw_params *params)
{
        struct tascam_card *tascam = snd_pcm_substream_chip(substream);
        int err;
        unsigned int rate = params_rate(params);

        if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
                tascam->fpo.sample_rate_khz = rate / 1000;
                tascam->fpo.base_feedback_value = tascam->fpo.sample_rate_khz;
                tascam->fpo.feedback_offset = 2;
                tascam->fpo.current_index = 0;
                tascam->fpo.previous_index = 0;
                tascam->fpo.sync_locked = false;

                unsigned int initial_value = tascam->fpo.sample_rate_khz / 8;

                for (int i = 0; i < 5; i++) {
                        int target_sum = tascam->fpo.sample_rate_khz -
                                         tascam->fpo.feedback_offset + i;
                        fpo_init_pattern(8, tascam->fpo.full_frame_patterns[i],
                                               initial_value, target_sum);
                }
        }

        if (tascam->current_rate != rate) {
                err = us144mkii_configure_device_for_rate(tascam, rate);
                if (err < 0) {
                        tascam->current_rate = 0;
                        return err;
                }
                tascam->current_rate = rate;
        }

        return 0;
}

int tascam_pcm_hw_free(struct snd_pcm_substream *substream)
{
        return 0;
}

int tascam_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
{
        struct tascam_card *tascam = snd_pcm_substream_chip(substream);
        int err = 0;
        int i;
        bool do_start = false;
        bool do_stop = false;

        scoped_guard(spinlock_irqsave, &tascam->lock) {
                switch (cmd) {
                case SNDRV_PCM_TRIGGER_START:
                case SNDRV_PCM_TRIGGER_RESUME:
                        if (!atomic_read(&tascam->playback_active)) {
                                atomic_set(&tascam->playback_active, 1);
                                atomic_set(&tascam->capture_active, 1);
                                do_start = true;
                        }
                        break;
                case SNDRV_PCM_TRIGGER_STOP:
                case SNDRV_PCM_TRIGGER_SUSPEND:
                case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
                        if (atomic_read(&tascam->playback_active)) {
                                atomic_set(&tascam->playback_active, 0);
                                atomic_set(&tascam->capture_active, 0);
                                do_stop = true;
                        }
                        break;
                default:
                        err = -EINVAL;
                        break;
                }
        }

        if (do_start) {
                if (atomic_read(&tascam->active_urbs) > 0) {
                        dev_warn(tascam->card->dev,
                                 "Cannot start, URBs still active.\n");
                        return -EAGAIN;
                }

                for (i = 0; i < NUM_FEEDBACK_URBS; i++) {
                        usb_get_urb(tascam->feedback_urbs[i]);
                        usb_anchor_urb(tascam->feedback_urbs[i],
                                               &tascam->feedback_anchor);
                        err = usb_submit_urb(tascam->feedback_urbs[i],
                                                     GFP_ATOMIC);
                        if (err < 0) {
                                usb_unanchor_urb(tascam->feedback_urbs[i]);
                                usb_put_urb(tascam->feedback_urbs[i]);
                                atomic_dec(&tascam->active_urbs);
                                goto start_rollback;
                        }
                        atomic_inc(&tascam->active_urbs);
                }
                for (i = 0; i < NUM_PLAYBACK_URBS; i++) {
                        usb_get_urb(tascam->playback_urbs[i]);
                        usb_anchor_urb(tascam->playback_urbs[i],
                                               &tascam->playback_anchor);
                        err = usb_submit_urb(tascam->playback_urbs[i],
                                                     GFP_ATOMIC);
                        if (err < 0) {
                                usb_unanchor_urb(tascam->playback_urbs[i]);
                                usb_put_urb(tascam->playback_urbs[i]);
                                atomic_dec(&tascam->active_urbs);
                                goto start_rollback;
                        }
                        atomic_inc(&tascam->active_urbs);
                }
                for (i = 0; i < NUM_CAPTURE_URBS; i++) {
                        usb_get_urb(tascam->capture_urbs[i]);
                        usb_anchor_urb(tascam->capture_urbs[i],
                                       &tascam->capture_anchor);
                        err = usb_submit_urb(tascam->capture_urbs[i],
                                             GFP_ATOMIC);
                        if (err < 0) {
                                usb_unanchor_urb(tascam->capture_urbs[i]);
                                usb_put_urb(tascam->capture_urbs[i]);
                                atomic_dec(&tascam->active_urbs);
                                goto start_rollback;
                        }
                        atomic_inc(&tascam->active_urbs);
                }

                return 0;
start_rollback:
                dev_err(tascam->card->dev,
                        "Failed to submit URBs to start stream: %d\n", err);
                do_stop = true;
        }

        if (do_stop)
                schedule_work(&tascam->stop_work);

        return err;
}

int tascam_init_pcm(struct snd_pcm *pcm)
{
        struct tascam_card *tascam = pcm->private_data;

        snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &tascam_playback_ops);
        snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &tascam_capture_ops);

        snd_pcm_set_managed_buffer_all(pcm, SNDRV_DMA_TYPE_CONTINUOUS,
                                       tascam->dev->dev.parent, 64 * 1024,
                                       tascam_pcm_hw.buffer_bytes_max);

        return 0;
}