// SPDX-License-Identifier: GPL-2.0
/*
 * video.c - V4L2 component for Mostcore
 *
 * Copyright (C) 2015, Microchip Technology Germany II GmbH & Co. KG
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/suspend.h>
#include <linux/videodev2.h>
#include <linux/mutex.h>
#include <media/v4l2-common.h>
#include <media/v4l2-ioctl.h>
#include <media/v4l2-event.h>
#include <media/v4l2-device.h>
#include <media/v4l2-ctrls.h>
#include <media/v4l2-fh.h>
#include <linux/most.h>

#define V4L2_CMP_MAX_INPUT  1

static struct most_component comp;

struct most_video_dev {
        struct most_interface *iface;
        int ch_idx;
        struct list_head list;
        bool mute;

        struct list_head pending_mbos;
        spinlock_t list_lock;

        struct v4l2_device v4l2_dev;
        atomic_t access_ref;
        struct video_device *vdev;
        unsigned int ctrl_input;

        struct mutex lock;

        wait_queue_head_t wait_data;
};

struct comp_fh {
        /* must be the first field of this struct! */
        struct v4l2_fh fh;
        struct most_video_dev *mdev;
        u32 offs;
};

static inline struct comp_fh *to_comp_fh(struct file *filp)
{
        return container_of(file_to_v4l2_fh(filp), struct comp_fh, fh);
}

static LIST_HEAD(video_devices);
static DEFINE_SPINLOCK(list_lock);

static inline bool data_ready(struct most_video_dev *mdev)
{
        return !list_empty(&mdev->pending_mbos);
}

static inline struct mbo *get_top_mbo(struct most_video_dev *mdev)
{
        return list_first_entry(&mdev->pending_mbos, struct mbo, list);
}

static int comp_vdev_open(struct file *filp)
{
        int ret;
        struct video_device *vdev = video_devdata(filp);
        struct most_video_dev *mdev = video_drvdata(filp);
        struct comp_fh *fh;

        switch (vdev->vfl_type) {
        case VFL_TYPE_VIDEO:
                break;
        default:
                return -EINVAL;
        }

        fh = kzalloc_obj(*fh);
        if (!fh)
                return -ENOMEM;

        if (!atomic_inc_and_test(&mdev->access_ref)) {
                v4l2_err(&mdev->v4l2_dev, "too many clients\n");
                ret = -EBUSY;
                goto err_dec;
        }

        fh->mdev = mdev;
        v4l2_fh_init(&fh->fh, vdev);
        v4l2_fh_add(&fh->fh, filp);

        ret = most_start_channel(mdev->iface, mdev->ch_idx, &comp);
        if (ret) {
                v4l2_err(&mdev->v4l2_dev, "most_start_channel() failed\n");
                goto err_rm;
        }

        return 0;

err_rm:
        v4l2_fh_del(&fh->fh, filp);
        v4l2_fh_exit(&fh->fh);

err_dec:
        atomic_dec(&mdev->access_ref);
        kfree(fh);
        return ret;
}

static int comp_vdev_close(struct file *filp)
{
        struct comp_fh *fh = to_comp_fh(filp);
        struct most_video_dev *mdev = fh->mdev;
        struct mbo *mbo, *tmp;
        LIST_HEAD(free_list);

        /*
         * We need to put MBOs back before we call most_stop_channel()
         * to deallocate MBOs.
         * From the other hand mostcore still calling rx_completion()
         * to deliver MBOs until most_stop_channel() is called.
         * Use mute to work around this issue.
         * This must be implemented in core.
         */

        spin_lock_irq(&mdev->list_lock);
        mdev->mute = true;
        list_replace_init(&mdev->pending_mbos, &free_list);
        spin_unlock_irq(&mdev->list_lock);

        list_for_each_entry_safe(mbo, tmp, &free_list, list) {
                list_del_init(&mbo->list);
                most_put_mbo(mbo);
        }

        most_stop_channel(mdev->iface, mdev->ch_idx, &comp);
        mdev->mute = false;

        v4l2_fh_del(&fh->fh, filp);
        v4l2_fh_exit(&fh->fh);

        atomic_dec(&mdev->access_ref);
        kfree(fh);
        return 0;
}

static ssize_t comp_vdev_read(struct file *filp, char __user *buf,
                              size_t count, loff_t *pos)
{
        struct comp_fh *fh = to_comp_fh(filp);
        struct most_video_dev *mdev = fh->mdev;
        int ret = 0;

        if (*pos)
                return -ESPIPE;

        if (!mdev)
                return -ENODEV;

        /* wait for the first buffer */
        if (!(filp->f_flags & O_NONBLOCK)) {
                if (wait_event_interruptible(mdev->wait_data, data_ready(mdev)))
                        return -ERESTARTSYS;
        }

        if (!data_ready(mdev))
                return -EAGAIN;

        while (count > 0 && data_ready(mdev)) {
                struct mbo *const mbo = get_top_mbo(mdev);
                int const rem = mbo->processed_length - fh->offs;
                int const cnt = rem < count ? rem : count;

                if (copy_to_user(buf, mbo->virt_address + fh->offs, cnt)) {
                        v4l2_err(&mdev->v4l2_dev, "read: copy_to_user failed\n");
                        if (!ret)
                                ret = -EFAULT;
                        return ret;
                }

                fh->offs += cnt;
                count -= cnt;
                buf += cnt;
                ret += cnt;

                if (cnt >= rem) {
                        fh->offs = 0;
                        spin_lock_irq(&mdev->list_lock);
                        list_del(&mbo->list);
                        spin_unlock_irq(&mdev->list_lock);
                        most_put_mbo(mbo);
                }
        }
        return ret;
}

static __poll_t comp_vdev_poll(struct file *filp, poll_table *wait)
{
        struct comp_fh *fh = to_comp_fh(filp);
        struct most_video_dev *mdev = fh->mdev;
        __poll_t mask = 0;

        /* only wait if no data is available */
        if (!data_ready(mdev))
                poll_wait(filp, &mdev->wait_data, wait);
        if (data_ready(mdev))
                mask |= EPOLLIN | EPOLLRDNORM;

        return mask;
}

static void comp_set_format_struct(struct v4l2_format *f)
{
        f->fmt.pix.width = 8;
        f->fmt.pix.height = 8;
        f->fmt.pix.pixelformat = V4L2_PIX_FMT_MPEG;
        f->fmt.pix.bytesperline = 0;
        f->fmt.pix.sizeimage = 188 * 2;
        f->fmt.pix.colorspace = V4L2_COLORSPACE_REC709;
        f->fmt.pix.field = V4L2_FIELD_NONE;
        f->fmt.pix.priv = 0;
}

static int comp_set_format(struct most_video_dev *mdev, unsigned int cmd,
                           struct v4l2_format *format)
{
        if (format->fmt.pix.pixelformat != V4L2_PIX_FMT_MPEG)
                return -EINVAL;

        if (cmd == VIDIOC_TRY_FMT)
                return 0;

        comp_set_format_struct(format);

        return 0;
}

static int vidioc_querycap(struct file *file, void *priv,
                           struct v4l2_capability *cap)
{
        struct comp_fh *fh = priv;
        struct most_video_dev *mdev = fh->mdev;

        strscpy(cap->driver, "v4l2_component", sizeof(cap->driver));
        strscpy(cap->card, "MOST", sizeof(cap->card));
        snprintf(cap->bus_info, sizeof(cap->bus_info),
                 "%s", mdev->iface->description);
        return 0;
}

static int vidioc_enum_fmt_vid_cap(struct file *file, void *priv,
                                   struct v4l2_fmtdesc *f)
{
        if (f->index)
                return -EINVAL;

        strscpy(f->description, "MPEG", sizeof(f->description));
        f->type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
        f->flags = V4L2_FMT_FLAG_COMPRESSED;
        f->pixelformat = V4L2_PIX_FMT_MPEG;

        return 0;
}

static int vidioc_g_fmt_vid_cap(struct file *file, void *priv,
                                struct v4l2_format *f)
{
        comp_set_format_struct(f);
        return 0;
}

static int vidioc_try_fmt_vid_cap(struct file *file, void *priv,
                                  struct v4l2_format *f)
{
        struct comp_fh *fh = priv;
        struct most_video_dev *mdev = fh->mdev;

        return comp_set_format(mdev, VIDIOC_TRY_FMT, f);
}

static int vidioc_s_fmt_vid_cap(struct file *file, void *priv,
                                struct v4l2_format *f)
{
        struct comp_fh *fh = priv;
        struct most_video_dev *mdev = fh->mdev;

        return comp_set_format(mdev, VIDIOC_S_FMT, f);
}

static int vidioc_g_std(struct file *file, void *priv, v4l2_std_id *norm)
{
        *norm = V4L2_STD_UNKNOWN;
        return 0;
}

static int vidioc_enum_input(struct file *file, void *priv,
                             struct v4l2_input *input)
{
        struct comp_fh *fh = priv;
        struct most_video_dev *mdev = fh->mdev;

        if (input->index >= V4L2_CMP_MAX_INPUT)
                return -EINVAL;

        strscpy(input->name, "MOST Video", sizeof(input->name));
        input->type |= V4L2_INPUT_TYPE_CAMERA;
        input->audioset = 0;

        input->std = mdev->vdev->tvnorms;

        return 0;
}

static int vidioc_g_input(struct file *file, void *priv, unsigned int *i)
{
        struct comp_fh *fh = priv;
        struct most_video_dev *mdev = fh->mdev;
        *i = mdev->ctrl_input;
        return 0;
}

static int vidioc_s_input(struct file *file, void *priv, unsigned int index)
{
        struct comp_fh *fh = priv;
        struct most_video_dev *mdev = fh->mdev;

        if (index >= V4L2_CMP_MAX_INPUT)
                return -EINVAL;
        mdev->ctrl_input = index;
        return 0;
}

static const struct v4l2_file_operations comp_fops = {
        .owner      = THIS_MODULE,
        .open       = comp_vdev_open,
        .release    = comp_vdev_close,
        .read       = comp_vdev_read,
        .poll       = comp_vdev_poll,
        .unlocked_ioctl = video_ioctl2,
};

static const struct v4l2_ioctl_ops video_ioctl_ops = {
        .vidioc_querycap            = vidioc_querycap,
        .vidioc_enum_fmt_vid_cap    = vidioc_enum_fmt_vid_cap,
        .vidioc_g_fmt_vid_cap       = vidioc_g_fmt_vid_cap,
        .vidioc_try_fmt_vid_cap     = vidioc_try_fmt_vid_cap,
        .vidioc_s_fmt_vid_cap       = vidioc_s_fmt_vid_cap,
        .vidioc_g_std               = vidioc_g_std,
        .vidioc_enum_input          = vidioc_enum_input,
        .vidioc_g_input             = vidioc_g_input,
        .vidioc_s_input             = vidioc_s_input,
};

static const struct video_device comp_videodev_template = {
        .fops = &comp_fops,
        .release = video_device_release,
        .ioctl_ops = &video_ioctl_ops,
        .tvnorms = V4L2_STD_UNKNOWN,
        .device_caps = V4L2_CAP_READWRITE | V4L2_CAP_VIDEO_CAPTURE,
};

/**************************************************************************/

static struct most_video_dev *get_comp_dev(struct most_interface *iface, int channel_idx)
{
        struct most_video_dev *mdev;
        unsigned long flags;

        spin_lock_irqsave(&list_lock, flags);
        list_for_each_entry(mdev, &video_devices, list) {
                if (mdev->iface == iface && mdev->ch_idx == channel_idx) {
                        spin_unlock_irqrestore(&list_lock, flags);
                        return mdev;
                }
        }
        spin_unlock_irqrestore(&list_lock, flags);
        return NULL;
}

static int comp_rx_data(struct mbo *mbo)
{
        unsigned long flags;
        struct most_video_dev *mdev =
                get_comp_dev(mbo->ifp, mbo->hdm_channel_id);

        if (!mdev)
                return -EIO;

        spin_lock_irqsave(&mdev->list_lock, flags);
        if (unlikely(mdev->mute)) {
                spin_unlock_irqrestore(&mdev->list_lock, flags);
                return -EIO;
        }

        list_add_tail(&mbo->list, &mdev->pending_mbos);
        spin_unlock_irqrestore(&mdev->list_lock, flags);
        wake_up_interruptible(&mdev->wait_data);
        return 0;
}

static int comp_register_videodev(struct most_video_dev *mdev)
{
        int ret;

        init_waitqueue_head(&mdev->wait_data);

        /* allocate and fill v4l2 video struct */
        mdev->vdev = video_device_alloc();
        if (!mdev->vdev)
                return -ENOMEM;

        /* Fill the video capture device struct */
        *mdev->vdev = comp_videodev_template;
        mdev->vdev->v4l2_dev = &mdev->v4l2_dev;
        mdev->vdev->lock = &mdev->lock;
        snprintf(mdev->vdev->name, sizeof(mdev->vdev->name), "MOST: %s",
                 mdev->v4l2_dev.name);

        /* Register the v4l2 device */
        video_set_drvdata(mdev->vdev, mdev);
        ret = video_register_device(mdev->vdev, VFL_TYPE_VIDEO, -1);
        if (ret) {
                v4l2_err(&mdev->v4l2_dev, "video_register_device failed (%d)\n",
                         ret);
                video_device_release(mdev->vdev);
        }

        return ret;
}

static void comp_unregister_videodev(struct most_video_dev *mdev)
{
        video_unregister_device(mdev->vdev);
}

static void comp_v4l2_dev_release(struct v4l2_device *v4l2_dev)
{
        struct most_video_dev *mdev =
                container_of(v4l2_dev, struct most_video_dev, v4l2_dev);

        v4l2_device_unregister(v4l2_dev);
        kfree(mdev);
}

static int comp_probe_channel(struct most_interface *iface, int channel_idx,
                              struct most_channel_config *ccfg, char *name,
                              char *args)
{
        int ret;
        struct most_video_dev *mdev = get_comp_dev(iface, channel_idx);

        if (mdev) {
                pr_err("Channel already linked\n");
                return -EEXIST;
        }

        if (ccfg->direction != MOST_CH_RX) {
                pr_err("Wrong direction, expected rx\n");
                return -EINVAL;
        }

        if (ccfg->data_type != MOST_CH_SYNC &&
            ccfg->data_type != MOST_CH_ISOC) {
                pr_err("Wrong channel type, expected sync or isoc\n");
                return -EINVAL;
        }

        mdev = kzalloc_obj(*mdev);
        if (!mdev)
                return -ENOMEM;

        mutex_init(&mdev->lock);
        atomic_set(&mdev->access_ref, -1);
        spin_lock_init(&mdev->list_lock);
        INIT_LIST_HEAD(&mdev->pending_mbos);
        mdev->iface = iface;
        mdev->ch_idx = channel_idx;
        mdev->v4l2_dev.release = comp_v4l2_dev_release;

        /* Create the v4l2_device */
        strscpy(mdev->v4l2_dev.name, name, sizeof(mdev->v4l2_dev.name));
        ret = v4l2_device_register(NULL, &mdev->v4l2_dev);
        if (ret) {
                pr_err("v4l2_device_register() failed\n");
                kfree(mdev);
                return ret;
        }

        ret = comp_register_videodev(mdev);
        if (ret)
                goto err_unreg;

        spin_lock_irq(&list_lock);
        list_add(&mdev->list, &video_devices);
        spin_unlock_irq(&list_lock);
        return 0;

err_unreg:
        v4l2_device_disconnect(&mdev->v4l2_dev);
        v4l2_device_put(&mdev->v4l2_dev);
        return ret;
}

static int comp_disconnect_channel(struct most_interface *iface,
                                   int channel_idx)
{
        struct most_video_dev *mdev = get_comp_dev(iface, channel_idx);

        if (!mdev) {
                pr_err("no such channel is linked\n");
                return -ENOENT;
        }

        spin_lock_irq(&list_lock);
        list_del(&mdev->list);
        spin_unlock_irq(&list_lock);

        comp_unregister_videodev(mdev);
        v4l2_device_disconnect(&mdev->v4l2_dev);
        v4l2_device_put(&mdev->v4l2_dev);
        return 0;
}

static struct most_component comp = {
        .mod = THIS_MODULE,
        .name = "video",
        .probe_channel = comp_probe_channel,
        .disconnect_channel = comp_disconnect_channel,
        .rx_completion = comp_rx_data,
};

static int __init comp_init(void)
{
        int err;

        err = most_register_component(&comp);
        if (err)
                return err;
        err = most_register_configfs_subsys(&comp);
        if (err) {
                most_deregister_component(&comp);
                return err;
        }
        return 0;
}

static void __exit comp_exit(void)
{
        struct most_video_dev *mdev, *tmp;
        LIST_HEAD(free_list);

        /*
         * As the mostcore currently doesn't call disconnect_channel()
         * for linked channels while we call most_deregister_component()
         * we simulate this call here.
         * This must be fixed in core.
         */
        spin_lock_irq(&list_lock);
        list_replace_init(&video_devices, &free_list);
        spin_unlock_irq(&list_lock);

        list_for_each_entry_safe(mdev, tmp, &free_list, list) {
                list_del_init(&mdev->list);
                comp_unregister_videodev(mdev);
                v4l2_device_disconnect(&mdev->v4l2_dev);
                v4l2_device_put(&mdev->v4l2_dev);
        }

        most_deregister_configfs_subsys(&comp);
        most_deregister_component(&comp);
        BUG_ON(!list_empty(&video_devices));
}

module_init(comp_init);
module_exit(comp_exit);

MODULE_DESCRIPTION("V4L2 Component Module for Mostcore");
MODULE_AUTHOR("Andrey Shvetsov <andrey.shvetsov@k2l.de>");
MODULE_LICENSE("GPL");