/*
 * video stream multiplexer controlled via mux control
 *
 * Copyright (C) 2013 Pengutronix, Sascha Hauer <kernel@pengutronix.de>
 * Copyright (C) 2016-2017 Pengutronix, Philipp Zabel <kernel@pengutronix.de>
 *
 * 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/err.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/regmap.h>
#include <linux/mfd/syscon.h>
#include <linux/of.h>
#include <linux/of_graph.h>
#include <linux/platform_device.h>
#include <media/v4l2-async.h>
#include <media/v4l2-device.h>
#include <media/v4l2-subdev.h>

struct video_mux {
	struct v4l2_subdev subdev;
	struct media_pad *pads;
	struct v4l2_mbus_framefmt *format_mbus;
	struct regmap_field *field;
	struct mutex lock;
	int active;
};

static inline struct video_mux *v4l2_subdev_to_video_mux(struct v4l2_subdev *sd)
{
	return container_of(sd, struct video_mux, subdev);
}

static int video_mux_link_setup(struct media_entity *entity,
				const struct media_pad *local,
				const struct media_pad *remote, u32 flags)
{
	struct v4l2_subdev *sd = media_entity_to_v4l2_subdev(entity);
	struct video_mux *vmux = v4l2_subdev_to_video_mux(sd);
	int ret = 0;

	/*
	 * The mux state is determined by the enabled sink pad link.
	 * Enabling or disabling the source pad link has no effect.
	 */
	if (local->flags & MEDIA_PAD_FL_SOURCE)
		return 0;

	dev_dbg(sd->dev, "link setup '%s':%d->'%s':%d[%d]",
		remote->entity->name, remote->index, local->entity->name,
		local->index, flags & MEDIA_LNK_FL_ENABLED);

	mutex_lock(&vmux->lock);

	if (flags & MEDIA_LNK_FL_ENABLED) {
		if (vmux->active == local->index)
			goto out;

		if (vmux->active >= 0) {
			ret = -EBUSY;
			goto out;
		}

		dev_dbg(sd->dev, "setting %d active\n", local->index);
		ret = regmap_field_write(vmux->field, local->index);
		if (ret < 0)
			goto out;
		vmux->active = local->index;
	} else {
		if (vmux->active != local->index)
			goto out;

		dev_dbg(sd->dev, "going inactive\n");
		vmux->active = -1;
	}

out:
	mutex_unlock(&vmux->lock);
	return ret;
}

static const struct media_entity_operations video_mux_ops = {
	.link_setup = video_mux_link_setup,
	.link_validate = v4l2_subdev_link_validate,
};

static int video_mux_s_stream(struct v4l2_subdev *sd, int enable)
{
	struct video_mux *vmux = v4l2_subdev_to_video_mux(sd);
	struct v4l2_subdev *upstream_sd;
	struct media_pad *pad;

	if (vmux->active == -1) {
		dev_err(sd->dev, "Can not start streaming on inactive mux\n");
		return -EINVAL;
	}

	pad = media_entity_remote_pad(&sd->entity.pads[vmux->active]);
	if (!pad) {
		dev_err(sd->dev, "Failed to find remote source pad\n");
		return -ENOLINK;
	}

	if (!is_media_entity_v4l2_subdev(pad->entity)) {
		dev_err(sd->dev, "Upstream entity is not a v4l2 subdev\n");
		return -ENODEV;
	}

	upstream_sd = media_entity_to_v4l2_subdev(pad->entity);

	return v4l2_subdev_call(upstream_sd, video, s_stream, enable);
}

static const struct v4l2_subdev_video_ops video_mux_subdev_video_ops = {
	.s_stream = video_mux_s_stream,
};

static struct v4l2_mbus_framefmt *
__video_mux_get_pad_format(struct v4l2_subdev *sd,
			   struct v4l2_subdev_pad_config *cfg,
			   unsigned int pad, u32 which)
{
	struct video_mux *vmux = v4l2_subdev_to_video_mux(sd);

	switch (which) {
	case V4L2_SUBDEV_FORMAT_TRY:
		return v4l2_subdev_get_try_format(sd, cfg, pad);
	case V4L2_SUBDEV_FORMAT_ACTIVE:
		return &vmux->format_mbus[pad];
	default:
		return NULL;
	}
}

static int video_mux_get_format(struct v4l2_subdev *sd,
			    struct v4l2_subdev_pad_config *cfg,
			    struct v4l2_subdev_format *sdformat)
{
	struct video_mux *vmux = v4l2_subdev_to_video_mux(sd);

	mutex_lock(&vmux->lock);

	sdformat->format = *__video_mux_get_pad_format(sd, cfg, sdformat->pad,
						       sdformat->which);

	mutex_unlock(&vmux->lock);

	return 0;
}

static int video_mux_set_format(struct v4l2_subdev *sd,
			    struct v4l2_subdev_pad_config *cfg,
			    struct v4l2_subdev_format *sdformat)
{
	struct video_mux *vmux = v4l2_subdev_to_video_mux(sd);
	struct v4l2_mbus_framefmt *mbusformat;
	struct media_pad *pad = &vmux->pads[sdformat->pad];

	mbusformat = __video_mux_get_pad_format(sd, cfg, sdformat->pad,
					    sdformat->which);
	if (!mbusformat)
		return -EINVAL;

	mutex_lock(&vmux->lock);

	/* Source pad mirrors active sink pad, no limitations on sink pads */
	if ((pad->flags & MEDIA_PAD_FL_SOURCE) && vmux->active >= 0)
		sdformat->format = vmux->format_mbus[vmux->active];

	*mbusformat = sdformat->format;

	mutex_unlock(&vmux->lock);

	return 0;
}

static const struct v4l2_subdev_pad_ops video_mux_pad_ops = {
	.get_fmt = video_mux_get_format,
	.set_fmt = video_mux_set_format,
};

static const struct v4l2_subdev_ops video_mux_subdev_ops = {
	.pad = &video_mux_pad_ops,
	.video = &video_mux_subdev_video_ops,
};

static int video_mux_probe_mmio_mux(struct video_mux *vmux)
{
	struct device *dev = vmux->subdev.dev;
	struct of_phandle_args args;
	struct reg_field field;
	struct regmap *regmap;
	u32 reg, mask;
	int ret;

	ret = of_parse_phandle_with_args(dev->of_node, "mux-controls",
					 "#mux-control-cells", 0, &args);
	if (ret)
		return ret;

	if (!of_device_is_compatible(args.np, "mmio-mux"))
		return -EINVAL;

	regmap = syscon_node_to_regmap(args.np->parent);
	if (IS_ERR(regmap))
		return PTR_ERR(regmap);

	ret = of_property_read_u32_index(args.np, "mux-reg-masks",
					 2 * args.args[0], &reg);
	if (!ret)
		ret = of_property_read_u32_index(args.np, "mux-reg-masks",
						 2 * args.args[0] + 1, &mask);
	if (ret < 0)
		return ret;

	field.reg = reg;
	field.msb = fls(mask) - 1;
	field.lsb = ffs(mask) - 1;

	vmux->field = devm_regmap_field_alloc(dev, regmap, field);
	if (IS_ERR(vmux->field))
		return PTR_ERR(vmux->field);

	return 0;
}

static int video_mux_probe(struct platform_device *pdev)
{
	struct device_node *np = pdev->dev.of_node;
	struct device *dev = &pdev->dev;
	struct device_node *ep;
	struct video_mux *vmux;
	unsigned int num_pads = 0;
	int ret;
	int i;

	vmux = devm_kzalloc(dev, sizeof(*vmux), GFP_KERNEL);
	if (!vmux)
		return -ENOMEM;

	platform_set_drvdata(pdev, vmux);

	v4l2_subdev_init(&vmux->subdev, &video_mux_subdev_ops);
	snprintf(vmux->subdev.name, sizeof(vmux->subdev.name), "%s", np->name);
	vmux->subdev.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
	vmux->subdev.dev = dev;

	/*
	 * The largest numbered port is the output port. It determines
	 * total number of pads.
	 */
	for_each_endpoint_of_node(np, ep) {
		struct of_endpoint endpoint;

		of_graph_parse_endpoint(ep, &endpoint);
		num_pads = max(num_pads, endpoint.port + 1);
	}

	if (num_pads < 2) {
		dev_err(dev, "Not enough ports %d\n", num_pads);
		return -EINVAL;
	}

	ret = video_mux_probe_mmio_mux(vmux);
	if (ret) {
		if (ret != -EPROBE_DEFER)
			dev_err(dev, "Failed to get mux: %d\n", ret);
		return ret;
	}

	mutex_init(&vmux->lock);
	vmux->active = -1;
	vmux->pads = devm_kcalloc(dev, num_pads, sizeof(*vmux->pads),
				  GFP_KERNEL);
	vmux->format_mbus = devm_kcalloc(dev, num_pads,
					 sizeof(*vmux->format_mbus),
					 GFP_KERNEL);

	for (i = 0; i < num_pads - 1; i++)
		vmux->pads[i].flags = MEDIA_PAD_FL_SINK;
	vmux->pads[num_pads - 1].flags = MEDIA_PAD_FL_SOURCE;

	vmux->subdev.entity.function = MEDIA_ENT_F_VID_MUX;
	ret = media_entity_pads_init(&vmux->subdev.entity, num_pads,
				     vmux->pads);
	if (ret < 0)
		return ret;

	vmux->subdev.entity.ops = &video_mux_ops;

	return v4l2_async_register_subdev(&vmux->subdev);
}

static int video_mux_remove(struct platform_device *pdev)
{
	struct video_mux *vmux = platform_get_drvdata(pdev);
	struct v4l2_subdev *sd = &vmux->subdev;

	v4l2_async_unregister_subdev(sd);
	media_entity_cleanup(&sd->entity);

	return 0;
}

static const struct of_device_id video_mux_dt_ids[] = {
	{ .compatible = "video-mux", },
	{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, video_mux_dt_ids);

static struct platform_driver video_mux_driver = {
	.probe		= video_mux_probe,
	.remove		= video_mux_remove,
	.driver		= {
		.of_match_table = video_mux_dt_ids,
		.name = "video-mux",
	},
};

module_platform_driver(video_mux_driver);

MODULE_DESCRIPTION("video stream multiplexer");
MODULE_AUTHOR("Sascha Hauer, Pengutronix");
MODULE_AUTHOR("Philipp Zabel, Pengutronix");
MODULE_LICENSE("GPL");