/*
 * V4L2 AIM - V4L2 Application Interface Module for MostCore
 *
 * Copyright (C) 2015, Microchip Technology Germany II GmbH & Co. KG
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * This file is licensed under GPLv2.
 */

#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 "mostcore.h"

#define V4L2_AIM_MAX_INPUT  1

static struct most_aim aim_info;

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

static struct list_head video_devices = LIST_HEAD_INIT(video_devices);
static struct 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 aim_vdev_open(struct file *filp)
{
        int ret;
        struct video_device *vdev = video_devdata(filp);
        struct most_video_dev *mdev = video_drvdata(filp);
        struct aim_fh *fh;

        pr_info("aim_vdev_open()\n");

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

        fh = kzalloc(sizeof(*fh), GFP_KERNEL);
        if (!fh)
                return -ENOMEM;

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

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

        v4l2_fh_add(&fh->fh);

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

        return 0;

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

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

static int aim_vdev_close(struct file *filp)
{
        struct aim_fh *fh = filp->private_data;
        struct most_video_dev *mdev = fh->mdev;
        struct mbo *mbo, *tmp;

        pr_info("aim_vdev_close()\n");

        /*
         * 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(&mdev->list_lock);
        mdev->mute = true;
        list_for_each_entry_safe(mbo, tmp, &mdev->pending_mbos, list) {
                list_del(&mbo->list);
                spin_unlock(&mdev->list_lock);
                most_put_mbo(mbo);
                spin_lock(&mdev->list_lock);
        }
        spin_unlock(&mdev->list_lock);
        most_stop_channel(mdev->iface, mdev->ch_idx, &aim_info);
        mdev->mute = false;

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

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

static ssize_t aim_vdev_read(struct file *filp, char __user *buf,
                             size_t count, loff_t *pos)
{
        struct aim_fh *fh = filp->private_data;
        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)) {
                        pr_err("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(&mdev->list_lock);
                        list_del(&mbo->list);
                        spin_unlock(&mdev->list_lock);
                        most_put_mbo(mbo);
                }
        }
        return ret;
}

static unsigned int aim_vdev_poll(struct file *filp, poll_table *wait)
{
        struct aim_fh *fh = filp->private_data;
        struct most_video_dev *mdev = fh->mdev;
        unsigned int 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 |= POLLIN | POLLRDNORM;

        return mask;
}

static void aim_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 aim_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;

        aim_set_format_struct(format);

        return 0;
}

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

        pr_info("vidioc_querycap()\n");

        strlcpy(cap->driver, "v4l2_most_aim", sizeof(cap->driver));
        strlcpy(cap->card, "my_card", sizeof(cap->card));
        snprintf(cap->bus_info, sizeof(cap->bus_info),
                 "%s", mdev->iface->description);

        cap->capabilities =
                V4L2_CAP_READWRITE |
                V4L2_CAP_TUNER |
                V4L2_CAP_VIDEO_CAPTURE;
        return 0;
}

static int vidioc_enum_fmt_vid_cap(struct file *file, void  *priv,
                                   struct v4l2_fmtdesc *f)
{
        pr_info("vidioc_enum_fmt_vid_cap() %d\n", f->index);

        if (f->index)
                return -EINVAL;

        strcpy(f->description, "MPEG");
        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)
{
        pr_info("vidioc_g_fmt_vid_cap()\n");

        aim_set_format_struct(f);
        return 0;
}

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

        return aim_set_format(mdev, VIDIOC_TRY_FMT, f);
}

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

        return aim_set_format(mdev, VIDIOC_S_FMT, f);
}

static int vidioc_g_std(struct file *file, void *priv, v4l2_std_id *norm)
{
        pr_info("vidioc_g_std()\n");

        *norm = V4L2_STD_UNKNOWN;
        return 0;
}

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

        if (input->index >= V4L2_AIM_MAX_INPUT)
                return -EINVAL;

        strcpy(input->name, "MOST Video");
        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 aim_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 aim_fh *fh = priv;
        struct most_video_dev *mdev = fh->mdev;

        pr_info("vidioc_s_input(%d)\n", index);

        if (index >= V4L2_AIM_MAX_INPUT)
                return -EINVAL;
        mdev->ctrl_input = index;
        return 0;
}

static struct v4l2_file_operations aim_fops = {
        .owner      = THIS_MODULE,
        .open       = aim_vdev_open,
        .release    = aim_vdev_close,
        .read       = aim_vdev_read,
        .poll       = aim_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 aim_videodev_template = {
        .fops = &aim_fops,
        .release = video_device_release,
        .ioctl_ops = &video_ioctl_ops,
        .tvnorms = V4L2_STD_UNKNOWN,
};

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

static struct most_video_dev *get_aim_dev(
        struct most_interface *iface, int channel_idx)
{
        struct most_video_dev *mdev, *tmp;

        spin_lock(&list_lock);
        list_for_each_entry_safe(mdev, tmp, &video_devices, list) {
                if (mdev->iface == iface && mdev->ch_idx == channel_idx) {
                        spin_unlock(&list_lock);
                        return mdev;
                }
        }
        spin_unlock(&list_lock);
        return NULL;
}

static int aim_rx_data(struct mbo *mbo)
{
        struct most_video_dev *mdev =
                get_aim_dev(mbo->ifp, mbo->hdm_channel_id);

        if (!mdev)
                return -EIO;

        spin_lock(&mdev->list_lock);
        if (unlikely(mdev->mute)) {
                spin_unlock(&mdev->list_lock);
                return -EIO;
        }

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

static int aim_register_videodev(struct most_video_dev *mdev)
{
        int retval = -ENOMEM;
        int ret;

        pr_info("aim_register_videodev()\n");

        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 = aim_videodev_template;
        mdev->vdev->v4l2_dev = &mdev->v4l2_dev;
        mdev->vdev->lock = &mdev->lock;
        strcpy(mdev->vdev->name, "most v4l2 aim video");

        /* Register the v4l2 device */
        video_set_drvdata(mdev->vdev, mdev);
        retval = video_register_device(mdev->vdev, VFL_TYPE_GRABBER, -1);
        if (retval != 0) {
                pr_err("video_register_device failed (%d)\n", retval);
                ret = -ENODEV;
                goto err_vbi_dev;
        }

        return 0;

err_vbi_dev:
        video_device_release(mdev->vdev);
        return ret;
}

static void aim_unregister_videodev(struct most_video_dev *mdev)
{
        pr_info("aim_unregister_videodev()\n");

        video_unregister_device(mdev->vdev);
}

static void aim_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 aim_probe_channel(struct most_interface *iface, int channel_idx,
                             struct most_channel_config *ccfg,
                             struct kobject *parent, char *name)
{
        int ret;
        struct most_video_dev *mdev = get_aim_dev(iface, channel_idx);

        pr_info("aim_probe_channel()\n");

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

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

        if (ccfg->data_type != MOST_CH_SYNC &&
            ccfg->data_type != MOST_CH_ISOC_AVP) {
                pr_err("wrong channel type, expect sync or isoc_avp\n");
                return -EINVAL;
        }

        mdev = kzalloc(sizeof(*mdev), GFP_KERNEL);
        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 = aim_v4l2_dev_release;

        /* Create the v4l2_device */
        strlcpy(mdev->v4l2_dev.name, "most_video_device",
                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 = aim_register_videodev(mdev);
        if (ret)
                goto err_unreg;

        spin_lock(&list_lock);
        list_add(&mdev->list, &video_devices);
        spin_unlock(&list_lock);
        return 0;

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

static int aim_disconnect_channel(struct most_interface *iface,
                                  int channel_idx)
{
        struct most_video_dev *mdev = get_aim_dev(iface, channel_idx);

        pr_info("aim_disconnect_channel()\n");

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

        spin_lock(&list_lock);
        list_del(&mdev->list);
        spin_unlock(&list_lock);

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

static struct most_aim aim_info = {
        .name = "v4l",
        .probe_channel = aim_probe_channel,
        .disconnect_channel = aim_disconnect_channel,
        .rx_completion = aim_rx_data,
};

static int __init aim_init(void)
{
        spin_lock_init(&list_lock);
        return most_register_aim(&aim_info);
}

static void __exit aim_exit(void)
{
        struct most_video_dev *mdev, *tmp;

        /*
         * As the mostcore currently doesn't call disconnect_channel()
         * for linked channels while we call most_deregister_aim()
         * we simulate this call here.
         * This must be fixed in core.
         */
        spin_lock(&list_lock);
        list_for_each_entry_safe(mdev, tmp, &video_devices, list) {
                list_del(&mdev->list);
                spin_unlock(&list_lock);

                aim_unregister_videodev(mdev);
                v4l2_device_disconnect(&mdev->v4l2_dev);
                v4l2_device_put(&mdev->v4l2_dev);
                spin_lock(&list_lock);
        }
        spin_unlock(&list_lock);

        most_deregister_aim(&aim_info);
        BUG_ON(!list_empty(&video_devices));
}

module_init(aim_init);
module_exit(aim_exit);

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