/*
 * vimc-sensor.c Virtual Media Controller Driver
 *
 * Copyright (C) 2015-2017 Helen Koike <helen.fornazier@gmail.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * 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.
 *
 */

#include <linux/freezer.h>
#include <linux/kthread.h>
#include <linux/v4l2-mediabus.h>
#include <linux/vmalloc.h>
#include <media/v4l2-subdev.h>

#include "vimc-sensor.h"

struct vimc_sen_device {
	struct vimc_ent_device ved;
	struct v4l2_subdev sd;
	struct task_struct *kthread_sen;
	u8 *frame;
	/* The active format */
	struct v4l2_mbus_framefmt mbus_format;
	int frame_size;
};

static int vimc_sen_enum_mbus_code(struct v4l2_subdev *sd,
				   struct v4l2_subdev_pad_config *cfg,
				   struct v4l2_subdev_mbus_code_enum *code)
{
	struct vimc_sen_device *vsen =
				container_of(sd, struct vimc_sen_device, sd);

	/* TODO: Add support for other codes */
	if (code->index)
		return -EINVAL;

	code->code = vsen->mbus_format.code;

	return 0;
}

static int vimc_sen_enum_frame_size(struct v4l2_subdev *sd,
				    struct v4l2_subdev_pad_config *cfg,
				    struct v4l2_subdev_frame_size_enum *fse)
{
	struct vimc_sen_device *vsen =
				container_of(sd, struct vimc_sen_device, sd);

	/* TODO: Add support to other formats */
	if (fse->index)
		return -EINVAL;

	/* TODO: Add support for other codes */
	if (fse->code != vsen->mbus_format.code)
		return -EINVAL;

	fse->min_width = vsen->mbus_format.width;
	fse->max_width = vsen->mbus_format.width;
	fse->min_height = vsen->mbus_format.height;
	fse->max_height = vsen->mbus_format.height;

	return 0;
}

static int vimc_sen_get_fmt(struct v4l2_subdev *sd,
			    struct v4l2_subdev_pad_config *cfg,
			    struct v4l2_subdev_format *format)
{
	struct vimc_sen_device *vsen =
				container_of(sd, struct vimc_sen_device, sd);

	format->format = vsen->mbus_format;

	return 0;
}

static const struct v4l2_subdev_pad_ops vimc_sen_pad_ops = {
	.enum_mbus_code		= vimc_sen_enum_mbus_code,
	.enum_frame_size	= vimc_sen_enum_frame_size,
	.get_fmt		= vimc_sen_get_fmt,
	/* TODO: Add support to other formats */
	.set_fmt		= vimc_sen_get_fmt,
};

/* media operations */
static const struct media_entity_operations vimc_sen_mops = {
	.link_validate = v4l2_subdev_link_validate,
};

static int vimc_thread_sen(void *data)
{
	struct vimc_sen_device *vsen = data;
	unsigned int i;

	set_freezable();
	set_current_state(TASK_UNINTERRUPTIBLE);

	for (;;) {
		try_to_freeze();
		if (kthread_should_stop())
			break;

		memset(vsen->frame, 100, vsen->frame_size);

		/* Send the frame to all source pads */
		for (i = 0; i < vsen->sd.entity.num_pads; i++)
			vimc_propagate_frame(&vsen->sd.entity.pads[i],
					     vsen->frame);

		/* 60 frames per second */
		schedule_timeout(HZ/60);
	}

	return 0;
}

static int vimc_sen_s_stream(struct v4l2_subdev *sd, int enable)
{
	struct vimc_sen_device *vsen =
				container_of(sd, struct vimc_sen_device, sd);
	int ret;

	if (enable) {
		const struct vimc_pix_map *vpix;

		if (vsen->kthread_sen)
			return -EINVAL;

		/* Calculate the frame size */
		vpix = vimc_pix_map_by_code(vsen->mbus_format.code);
		vsen->frame_size = vsen->mbus_format.width * vpix->bpp *
				   vsen->mbus_format.height;

		/*
		 * Allocate the frame buffer. Use vmalloc to be able to
		 * allocate a large amount of memory
		 */
		vsen->frame = vmalloc(vsen->frame_size);
		if (!vsen->frame)
			return -ENOMEM;

		/* Initialize the image generator thread */
		vsen->kthread_sen = kthread_run(vimc_thread_sen, vsen, "%s-sen",
						vsen->sd.v4l2_dev->name);
		if (IS_ERR(vsen->kthread_sen)) {
			dev_err(vsen->sd.v4l2_dev->dev,
				"%s: kernel_thread() failed\n",	vsen->sd.name);
			vfree(vsen->frame);
			vsen->frame = NULL;
			return PTR_ERR(vsen->kthread_sen);
		}
	} else {
		if (!vsen->kthread_sen)
			return -EINVAL;

		/* Stop image generator */
		ret = kthread_stop(vsen->kthread_sen);
		vsen->kthread_sen = NULL;

		vfree(vsen->frame);
		vsen->frame = NULL;
		return ret;
	}

	return 0;
}

struct v4l2_subdev_video_ops vimc_sen_video_ops = {
	.s_stream = vimc_sen_s_stream,
};

static const struct v4l2_subdev_ops vimc_sen_ops = {
	.pad = &vimc_sen_pad_ops,
	.video = &vimc_sen_video_ops,
};

static void vimc_sen_destroy(struct vimc_ent_device *ved)
{
	struct vimc_sen_device *vsen =
				container_of(ved, struct vimc_sen_device, ved);

	v4l2_device_unregister_subdev(&vsen->sd);
	media_entity_cleanup(ved->ent);
	kfree(vsen);
}

struct vimc_ent_device *vimc_sen_create(struct v4l2_device *v4l2_dev,
					const char *const name,
					u16 num_pads,
					const unsigned long *pads_flag)
{
	struct vimc_sen_device *vsen;
	unsigned int i;
	int ret;

	/* NOTE: a sensor node may be created with more then one pad */
	if (!name || !num_pads || !pads_flag)
		return ERR_PTR(-EINVAL);

	/* check if all pads are sources */
	for (i = 0; i < num_pads; i++)
		if (!(pads_flag[i] & MEDIA_PAD_FL_SOURCE))
			return ERR_PTR(-EINVAL);

	/* Allocate the vsen struct */
	vsen = kzalloc(sizeof(*vsen), GFP_KERNEL);
	if (!vsen)
		return ERR_PTR(-ENOMEM);

	/* Allocate the pads */
	vsen->ved.pads = vimc_pads_init(num_pads, pads_flag);
	if (IS_ERR(vsen->ved.pads)) {
		ret = PTR_ERR(vsen->ved.pads);
		goto err_free_vsen;
	}

	/* Fill the vimc_ent_device struct */
	vsen->ved.destroy = vimc_sen_destroy;
	vsen->ved.ent = &vsen->sd.entity;

	/* Initialize the subdev */
	v4l2_subdev_init(&vsen->sd, &vimc_sen_ops);
	vsen->sd.entity.function = MEDIA_ENT_F_CAM_SENSOR;
	vsen->sd.entity.ops = &vimc_sen_mops;
	vsen->sd.owner = THIS_MODULE;
	strlcpy(vsen->sd.name, name, sizeof(vsen->sd.name));
	v4l2_set_subdevdata(&vsen->sd, &vsen->ved);

	/* Expose this subdev to user space */
	vsen->sd.flags = V4L2_SUBDEV_FL_HAS_DEVNODE;

	/* Initialize the media entity */
	ret = media_entity_pads_init(&vsen->sd.entity,
				     num_pads, vsen->ved.pads);
	if (ret)
		goto err_clean_pads;

	/* Set the active frame format (this is hardcoded for now) */
	vsen->mbus_format.width = 640;
	vsen->mbus_format.height = 480;
	vsen->mbus_format.code = MEDIA_BUS_FMT_RGB888_1X24;
	vsen->mbus_format.field = V4L2_FIELD_NONE;
	vsen->mbus_format.colorspace = V4L2_COLORSPACE_SRGB;
	vsen->mbus_format.quantization = V4L2_QUANTIZATION_FULL_RANGE;
	vsen->mbus_format.xfer_func = V4L2_XFER_FUNC_SRGB;

	/* Register the subdev with the v4l2 and the media framework */
	ret = v4l2_device_register_subdev(v4l2_dev, &vsen->sd);
	if (ret) {
		dev_err(vsen->sd.v4l2_dev->dev,
			"%s: subdev register failed (err=%d)\n",
			vsen->sd.name, ret);
		goto err_clean_m_ent;
	}

	return &vsen->ved;

err_clean_m_ent:
	media_entity_cleanup(&vsen->sd.entity);
err_clean_pads:
	vimc_pads_cleanup(vsen->ved.pads);
err_free_vsen:
	kfree(vsen);

	return ERR_PTR(ret);
}