// SPDX-License-Identifier: GPL-2.0-only
/*
 * Line 6 Linux USB driver
 *
 * Copyright (C) 2004-2010 Markus Grabner (line6@grabner-graz.at)
 */

#include <linux/slab.h>
#include <sound/core.h>
#include <sound/pcm.h>
#include <sound/pcm_params.h>

#include "capture.h"
#include "driver.h"
#include "pcm.h"

/*
        Find a free URB and submit it.
        must be called in line6pcm->in.lock context
*/
static int submit_audio_in_urb(struct snd_line6_pcm *line6pcm)
{
        int index;
        int i, urb_size;
        int ret;
        struct urb *urb_in;

        index = find_first_zero_bit(&line6pcm->in.active_urbs,
                                    line6pcm->line6->iso_buffers);

        if (index < 0 || index >= line6pcm->line6->iso_buffers) {
                dev_err(line6pcm->line6->ifcdev, "no free URB found\n");
                return -EINVAL;
        }

        urb_in = line6pcm->in.urbs[index];
        urb_size = 0;

        for (i = 0; i < LINE6_ISO_PACKETS; ++i) {
                struct usb_iso_packet_descriptor *fin =
                    &urb_in->iso_frame_desc[i];
                fin->offset = urb_size;
                fin->length = line6pcm->max_packet_size_in;
                urb_size += line6pcm->max_packet_size_in;
        }

        urb_in->transfer_buffer =
            line6pcm->in.buffer +
            index * LINE6_ISO_PACKETS * line6pcm->max_packet_size_in;
        urb_in->transfer_buffer_length = urb_size;
        urb_in->context = line6pcm;

        ret = usb_submit_urb(urb_in, GFP_ATOMIC);

        if (ret == 0)
                set_bit(index, &line6pcm->in.active_urbs);
        else
                dev_err(line6pcm->line6->ifcdev,
                        "URB in #%d submission failed (%d)\n", index, ret);

        return 0;
}

/*
        Submit all currently available capture URBs.
        must be called in line6pcm->in.lock context
*/
int line6_submit_audio_in_all_urbs(struct snd_line6_pcm *line6pcm)
{
        int ret = 0, i;

        for (i = 0; i < line6pcm->line6->iso_buffers; ++i) {
                ret = submit_audio_in_urb(line6pcm);
                if (ret < 0)
                        break;
        }

        return ret;
}

/*
        Copy data into ALSA capture buffer.
*/
void line6_capture_copy(struct snd_line6_pcm *line6pcm, char *fbuf, int fsize)
{
        struct snd_pcm_substream *substream =
            get_substream(line6pcm, SNDRV_PCM_STREAM_CAPTURE);
        struct snd_pcm_runtime *runtime = substream->runtime;
        const int bytes_per_frame =
                line6pcm->properties->bytes_per_channel *
                line6pcm->properties->capture_hw.channels_max;
        int frames = fsize / bytes_per_frame;

        if (runtime == NULL)
                return;

        if (line6pcm->in.pos_done + frames > runtime->buffer_size) {
                /*
                   The transferred area goes over buffer boundary,
                   copy two separate chunks.
                 */
                int len;

                len = runtime->buffer_size - line6pcm->in.pos_done;

                if (len > 0) {
                        memcpy(runtime->dma_area +
                               line6pcm->in.pos_done * bytes_per_frame, fbuf,
                               len * bytes_per_frame);
                        memcpy(runtime->dma_area, fbuf + len * bytes_per_frame,
                               (frames - len) * bytes_per_frame);
                } else {
                        /* this is somewhat paranoid */
                        dev_err(line6pcm->line6->ifcdev,
                                "driver bug: len = %d\n", len);
                }
        } else {
                /* copy single chunk */
                memcpy(runtime->dma_area +
                       line6pcm->in.pos_done * bytes_per_frame, fbuf, fsize);
        }

        line6pcm->in.pos_done += frames;
        if (line6pcm->in.pos_done >= runtime->buffer_size)
                line6pcm->in.pos_done -= runtime->buffer_size;
}

void line6_capture_check_period(struct snd_line6_pcm *line6pcm, int length)
{
        struct snd_pcm_substream *substream =
            get_substream(line6pcm, SNDRV_PCM_STREAM_CAPTURE);

        line6pcm->in.bytes += length;
        if (line6pcm->in.bytes >= line6pcm->in.period) {
                line6pcm->in.bytes %= line6pcm->in.period;
                spin_unlock(&line6pcm->in.lock);
                snd_pcm_period_elapsed(substream);
                spin_lock(&line6pcm->in.lock);
        }
}

/*
 * Callback for completed capture URB.
 */
static void audio_in_callback(struct urb *urb)
{
        int i, index, length = 0, shutdown = 0;
        struct snd_line6_pcm *line6pcm = (struct snd_line6_pcm *)urb->context;

        line6pcm->in.last_frame = urb->start_frame;

        /* find index of URB */
        for (index = 0; index < line6pcm->line6->iso_buffers; ++index)
                if (urb == line6pcm->in.urbs[index])
                        break;

        guard(spinlock_irqsave)(&line6pcm->in.lock);

        for (i = 0; i < LINE6_ISO_PACKETS; ++i) {
                char *fbuf;
                int fsize;
                struct usb_iso_packet_descriptor *fin = &urb->iso_frame_desc[i];

                if (fin->status == -EXDEV) {
                        shutdown = 1;
                        break;
                }

                fbuf = urb->transfer_buffer + fin->offset;
                fsize = fin->actual_length;

                if (fsize > line6pcm->max_packet_size_in) {
                        dev_err(line6pcm->line6->ifcdev,
                                "driver and/or device bug: packet too large (%d > %d)\n",
                                fsize, line6pcm->max_packet_size_in);
                }

                length += fsize;

                BUILD_BUG_ON_MSG(LINE6_ISO_PACKETS != 1,
                        "The following code assumes LINE6_ISO_PACKETS == 1");
                /* TODO:
                 * Also, if iso_buffers != 2, the prev frame is almost random at
                 * playback side.
                 * This needs to be redesigned. It should be "stable", but we may
                 * experience sync problems on such high-speed configs.
                 */

                line6pcm->prev_fbuf = fbuf;
                line6pcm->prev_fsize = fsize /
                        (line6pcm->properties->bytes_per_channel *
                        line6pcm->properties->capture_hw.channels_max);

                if (!test_bit(LINE6_STREAM_IMPULSE, &line6pcm->in.running) &&
                    test_bit(LINE6_STREAM_PCM, &line6pcm->in.running) &&
                    fsize > 0)
                        line6_capture_copy(line6pcm, fbuf, fsize);
        }

        clear_bit(index, &line6pcm->in.active_urbs);

        if (test_and_clear_bit(index, &line6pcm->in.unlink_urbs))
                shutdown = 1;

        if (!shutdown) {
                submit_audio_in_urb(line6pcm);

                if (!test_bit(LINE6_STREAM_IMPULSE, &line6pcm->in.running) &&
                    test_bit(LINE6_STREAM_PCM, &line6pcm->in.running))
                        line6_capture_check_period(line6pcm, length);
        }
}

/* open capture callback */
static int snd_line6_capture_open(struct snd_pcm_substream *substream)
{
        int err;
        struct snd_pcm_runtime *runtime = substream->runtime;
        struct snd_line6_pcm *line6pcm = snd_pcm_substream_chip(substream);

        err = snd_pcm_hw_constraint_ratdens(runtime, 0,
                                            SNDRV_PCM_HW_PARAM_RATE,
                                            &line6pcm->properties->rates);
        if (err < 0)
                return err;

        line6_pcm_acquire(line6pcm, LINE6_STREAM_CAPTURE_HELPER, false);

        runtime->hw = line6pcm->properties->capture_hw;
        return 0;
}

/* close capture callback */
static int snd_line6_capture_close(struct snd_pcm_substream *substream)
{
        struct snd_line6_pcm *line6pcm = snd_pcm_substream_chip(substream);

        line6_pcm_release(line6pcm, LINE6_STREAM_CAPTURE_HELPER);
        return 0;
}

/* capture operators */
const struct snd_pcm_ops snd_line6_capture_ops = {
        .open = snd_line6_capture_open,
        .close = snd_line6_capture_close,
        .hw_params = snd_line6_hw_params,
        .hw_free = snd_line6_hw_free,
        .prepare = snd_line6_prepare,
        .trigger = snd_line6_trigger,
        .pointer = snd_line6_pointer,
};

int line6_create_audio_in_urbs(struct snd_line6_pcm *line6pcm)
{
        struct usb_line6 *line6 = line6pcm->line6;
        int i;

        line6pcm->in.urbs = kzalloc_objs(struct urb *, line6->iso_buffers);
        if (line6pcm->in.urbs == NULL)
                return -ENOMEM;

        /* create audio URBs and fill in constant values: */
        for (i = 0; i < line6->iso_buffers; ++i) {
                struct urb *urb;

                /* URB for audio in: */
                urb = line6pcm->in.urbs[i] =
                    usb_alloc_urb(LINE6_ISO_PACKETS, GFP_KERNEL);

                if (urb == NULL)
                        return -ENOMEM;

                urb->dev = line6->usbdev;
                urb->pipe =
                    usb_rcvisocpipe(line6->usbdev,
                                    line6->properties->ep_audio_r &
                                    USB_ENDPOINT_NUMBER_MASK);
                urb->transfer_flags = URB_ISO_ASAP;
                urb->start_frame = -1;
                urb->number_of_packets = LINE6_ISO_PACKETS;
                urb->interval = LINE6_ISO_INTERVAL;
                urb->error_count = 0;
                urb->complete = audio_in_callback;
                if (usb_urb_ep_type_check(urb))
                        return -EINVAL;
        }

        return 0;
}