linux-zen-server/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi_bridge.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * Copyright 2021-2022 Bootlin
 * Author: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
 */

#include <linux/pm_runtime.h>
#include <linux/regmap.h>
#include <media/v4l2-device.h>
#include <media/v4l2-fwnode.h>

#include "sun6i_csi.h"
#include "sun6i_csi_bridge.h"
#include "sun6i_csi_reg.h"

/* Helpers */

void sun6i_csi_bridge_dimensions(struct sun6i_csi_device *csi_dev,
				 unsigned int *width, unsigned int *height)
{
	if (width)
		*width = csi_dev->bridge.mbus_format.width;
	if (height)
		*height = csi_dev->bridge.mbus_format.height;
}

void sun6i_csi_bridge_format(struct sun6i_csi_device *csi_dev,
			     u32 *mbus_code, u32 *field)
{
	if (mbus_code)
		*mbus_code = csi_dev->bridge.mbus_format.code;
	if (field)
		*field = csi_dev->bridge.mbus_format.field;
}

/* Format */

static const struct sun6i_csi_bridge_format sun6i_csi_bridge_formats[] = {
	/* Bayer */
	{
		.mbus_code		= MEDIA_BUS_FMT_SBGGR8_1X8,
		.input_format		= SUN6I_CSI_INPUT_FMT_RAW,
	},
	{
		.mbus_code		= MEDIA_BUS_FMT_SGBRG8_1X8,
		.input_format		= SUN6I_CSI_INPUT_FMT_RAW,
	},
	{
		.mbus_code		= MEDIA_BUS_FMT_SGRBG8_1X8,
		.input_format		= SUN6I_CSI_INPUT_FMT_RAW,
	},
	{
		.mbus_code		= MEDIA_BUS_FMT_SRGGB8_1X8,
		.input_format		= SUN6I_CSI_INPUT_FMT_RAW,
	},
	{
		.mbus_code		= MEDIA_BUS_FMT_SBGGR10_1X10,
		.input_format		= SUN6I_CSI_INPUT_FMT_RAW,
	},
	{
		.mbus_code		= MEDIA_BUS_FMT_SGBRG10_1X10,
		.input_format		= SUN6I_CSI_INPUT_FMT_RAW,
	},
	{
		.mbus_code		= MEDIA_BUS_FMT_SGRBG10_1X10,
		.input_format		= SUN6I_CSI_INPUT_FMT_RAW,
	},
	{
		.mbus_code		= MEDIA_BUS_FMT_SRGGB10_1X10,
		.input_format		= SUN6I_CSI_INPUT_FMT_RAW,
	},
	{
		.mbus_code		= MEDIA_BUS_FMT_SBGGR12_1X12,
		.input_format		= SUN6I_CSI_INPUT_FMT_RAW,
	},
	{
		.mbus_code		= MEDIA_BUS_FMT_SGBRG12_1X12,
		.input_format		= SUN6I_CSI_INPUT_FMT_RAW,
	},
	{
		.mbus_code		= MEDIA_BUS_FMT_SGRBG12_1X12,
		.input_format		= SUN6I_CSI_INPUT_FMT_RAW,
	},
	{
		.mbus_code		= MEDIA_BUS_FMT_SRGGB12_1X12,
		.input_format		= SUN6I_CSI_INPUT_FMT_RAW,
	},
	/* RGB */
	{
		.mbus_code		= MEDIA_BUS_FMT_RGB565_2X8_LE,
		.input_format		= SUN6I_CSI_INPUT_FMT_RAW,
	},
	{
		.mbus_code		= MEDIA_BUS_FMT_RGB565_2X8_BE,
		.input_format		= SUN6I_CSI_INPUT_FMT_RAW,
	},
	/* YUV422 */
	{
		.mbus_code		= MEDIA_BUS_FMT_YUYV8_2X8,
		.input_format		= SUN6I_CSI_INPUT_FMT_YUV422,
		.input_yuv_seq		= SUN6I_CSI_INPUT_YUV_SEQ_YUYV,
		.input_yuv_seq_invert	= SUN6I_CSI_INPUT_YUV_SEQ_YVYU,
	},
	{
		.mbus_code		= MEDIA_BUS_FMT_UYVY8_2X8,
		.input_format		= SUN6I_CSI_INPUT_FMT_YUV422,
		.input_yuv_seq		= SUN6I_CSI_INPUT_YUV_SEQ_UYVY,
		.input_yuv_seq_invert	= SUN6I_CSI_INPUT_YUV_SEQ_VYUY,
	},
	{
		.mbus_code		= MEDIA_BUS_FMT_YVYU8_2X8,
		.input_format		= SUN6I_CSI_INPUT_FMT_YUV422,
		.input_yuv_seq		= SUN6I_CSI_INPUT_YUV_SEQ_YVYU,
		.input_yuv_seq_invert	= SUN6I_CSI_INPUT_YUV_SEQ_YUYV,
	},
	{
		.mbus_code		= MEDIA_BUS_FMT_UYVY8_2X8,
		.input_format		= SUN6I_CSI_INPUT_FMT_YUV422,
		.input_yuv_seq		= SUN6I_CSI_INPUT_YUV_SEQ_UYVY,
		.input_yuv_seq_invert	= SUN6I_CSI_INPUT_YUV_SEQ_VYUY,
	},
	{
		.mbus_code		= MEDIA_BUS_FMT_VYUY8_2X8,
		.input_format		= SUN6I_CSI_INPUT_FMT_YUV422,
		.input_yuv_seq		= SUN6I_CSI_INPUT_YUV_SEQ_VYUY,
		.input_yuv_seq_invert	= SUN6I_CSI_INPUT_YUV_SEQ_UYVY,
	},
	{
		.mbus_code		= MEDIA_BUS_FMT_YUYV8_1X16,
		.input_format		= SUN6I_CSI_INPUT_FMT_YUV422,
		.input_yuv_seq		= SUN6I_CSI_INPUT_YUV_SEQ_YUYV,
		.input_yuv_seq_invert	= SUN6I_CSI_INPUT_YUV_SEQ_YVYU,
	},
	{
		.mbus_code		= MEDIA_BUS_FMT_UYVY8_1X16,
		.input_format		= SUN6I_CSI_INPUT_FMT_YUV422,
		.input_yuv_seq		= SUN6I_CSI_INPUT_YUV_SEQ_UYVY,
		.input_yuv_seq_invert	= SUN6I_CSI_INPUT_YUV_SEQ_VYUY,
	},
	{
		.mbus_code		= MEDIA_BUS_FMT_YVYU8_1X16,
		.input_format		= SUN6I_CSI_INPUT_FMT_YUV422,
		.input_yuv_seq		= SUN6I_CSI_INPUT_YUV_SEQ_YVYU,
		.input_yuv_seq_invert	= SUN6I_CSI_INPUT_YUV_SEQ_YUYV,
	},
	{
		.mbus_code		= MEDIA_BUS_FMT_UYVY8_1X16,
		.input_format		= SUN6I_CSI_INPUT_FMT_YUV422,
		.input_yuv_seq		= SUN6I_CSI_INPUT_YUV_SEQ_UYVY,
		.input_yuv_seq_invert	= SUN6I_CSI_INPUT_YUV_SEQ_VYUY,
	},
	{
		.mbus_code		= MEDIA_BUS_FMT_VYUY8_1X16,
		.input_format		= SUN6I_CSI_INPUT_FMT_YUV422,
		.input_yuv_seq		= SUN6I_CSI_INPUT_YUV_SEQ_VYUY,
		.input_yuv_seq_invert	= SUN6I_CSI_INPUT_YUV_SEQ_UYVY,
	},
	/* Compressed */
	{
		.mbus_code		= MEDIA_BUS_FMT_JPEG_1X8,
		.input_format		= SUN6I_CSI_INPUT_FMT_RAW,
	},
};

const struct sun6i_csi_bridge_format *
sun6i_csi_bridge_format_find(u32 mbus_code)
{
	unsigned int i;

	for (i = 0; i < ARRAY_SIZE(sun6i_csi_bridge_formats); i++)
		if (sun6i_csi_bridge_formats[i].mbus_code == mbus_code)
			return &sun6i_csi_bridge_formats[i];

	return NULL;
}

/* Bridge */

static void sun6i_csi_bridge_irq_enable(struct sun6i_csi_device *csi_dev)
{
	struct regmap *regmap = csi_dev->regmap;

	regmap_write(regmap, SUN6I_CSI_CH_INT_EN_REG,
		     SUN6I_CSI_CH_INT_EN_VS |
		     SUN6I_CSI_CH_INT_EN_HB_OF |
		     SUN6I_CSI_CH_INT_EN_FIFO2_OF |
		     SUN6I_CSI_CH_INT_EN_FIFO1_OF |
		     SUN6I_CSI_CH_INT_EN_FIFO0_OF |
		     SUN6I_CSI_CH_INT_EN_FD |
		     SUN6I_CSI_CH_INT_EN_CD);
}

static void sun6i_csi_bridge_irq_disable(struct sun6i_csi_device *csi_dev)
{
	struct regmap *regmap = csi_dev->regmap;

	regmap_write(regmap, SUN6I_CSI_CH_INT_EN_REG, 0);
}

static void sun6i_csi_bridge_irq_clear(struct sun6i_csi_device *csi_dev)
{
	struct regmap *regmap = csi_dev->regmap;

	regmap_write(regmap, SUN6I_CSI_CH_INT_EN_REG, 0);
	regmap_write(regmap, SUN6I_CSI_CH_INT_STA_REG,
		     SUN6I_CSI_CH_INT_STA_CLEAR);
}

static void sun6i_csi_bridge_enable(struct sun6i_csi_device *csi_dev)
{
	struct regmap *regmap = csi_dev->regmap;

	regmap_update_bits(regmap, SUN6I_CSI_EN_REG, SUN6I_CSI_EN_CSI_EN,
			   SUN6I_CSI_EN_CSI_EN);

	regmap_update_bits(regmap, SUN6I_CSI_CAP_REG, SUN6I_CSI_CAP_VCAP_ON,
			   SUN6I_CSI_CAP_VCAP_ON);
}

static void sun6i_csi_bridge_disable(struct sun6i_csi_device *csi_dev)
{
	struct regmap *regmap = csi_dev->regmap;

	regmap_update_bits(regmap, SUN6I_CSI_CAP_REG, SUN6I_CSI_CAP_VCAP_ON, 0);
	regmap_update_bits(regmap, SUN6I_CSI_EN_REG, SUN6I_CSI_EN_CSI_EN, 0);
}

static void
sun6i_csi_bridge_configure_parallel(struct sun6i_csi_device *csi_dev)
{
	struct device *dev = csi_dev->dev;
	struct regmap *regmap = csi_dev->regmap;
	struct v4l2_fwnode_endpoint *endpoint =
		&csi_dev->bridge.source_parallel.endpoint;
	unsigned char bus_width = endpoint->bus.parallel.bus_width;
	unsigned int flags = endpoint->bus.parallel.flags;
	u32 field;
	u32 value = SUN6I_CSI_IF_CFG_IF_CSI;

	sun6i_csi_bridge_format(csi_dev, NULL, &field);

	if (field == V4L2_FIELD_INTERLACED ||
	    field == V4L2_FIELD_INTERLACED_TB ||
	    field == V4L2_FIELD_INTERLACED_BT)
		value |= SUN6I_CSI_IF_CFG_SRC_TYPE_INTERLACED |
			 SUN6I_CSI_IF_CFG_FIELD_DT_PCLK_SHIFT(1) |
			 SUN6I_CSI_IF_CFG_FIELD_DT_FIELD_VSYNC;
	else
		value |= SUN6I_CSI_IF_CFG_SRC_TYPE_PROGRESSIVE;

	switch (endpoint->bus_type) {
	case V4L2_MBUS_PARALLEL:
		if (bus_width == 16)
			value |= SUN6I_CSI_IF_CFG_IF_CSI_YUV_COMBINED;
		else
			value |= SUN6I_CSI_IF_CFG_IF_CSI_YUV_RAW;

		if (flags & V4L2_MBUS_FIELD_EVEN_LOW)
			value |= SUN6I_CSI_IF_CFG_FIELD_NEGATIVE;
		else
			value |= SUN6I_CSI_IF_CFG_FIELD_POSITIVE;

		if (flags & V4L2_MBUS_VSYNC_ACTIVE_LOW)
			value |= SUN6I_CSI_IF_CFG_VREF_POL_NEGATIVE;
		else
			value |= SUN6I_CSI_IF_CFG_VREF_POL_POSITIVE;

		if (flags & V4L2_MBUS_HSYNC_ACTIVE_LOW)
			value |= SUN6I_CSI_IF_CFG_HREF_POL_NEGATIVE;
		else
			value |= SUN6I_CSI_IF_CFG_HREF_POL_POSITIVE;

		if (flags & V4L2_MBUS_PCLK_SAMPLE_RISING)
			value |= SUN6I_CSI_IF_CFG_CLK_POL_RISING;
		else
			value |= SUN6I_CSI_IF_CFG_CLK_POL_FALLING;
		break;
	case V4L2_MBUS_BT656:
		if (bus_width == 16)
			value |= SUN6I_CSI_IF_CFG_IF_CSI_BT1120;
		else
			value |= SUN6I_CSI_IF_CFG_IF_CSI_BT656;

		if (flags & V4L2_MBUS_FIELD_EVEN_LOW)
			value |= SUN6I_CSI_IF_CFG_FIELD_NEGATIVE;
		else
			value |= SUN6I_CSI_IF_CFG_FIELD_POSITIVE;

		if (flags & V4L2_MBUS_PCLK_SAMPLE_FALLING)
			value |= SUN6I_CSI_IF_CFG_CLK_POL_RISING;
		else
			value |= SUN6I_CSI_IF_CFG_CLK_POL_FALLING;
		break;
	default:
		dev_warn(dev, "unsupported bus type: %d\n", endpoint->bus_type);
		break;
	}

	switch (bus_width) {
	case 8:
	/* 16-bit YUV formats use a doubled width in 8-bit mode. */
	case 16:
		value |= SUN6I_CSI_IF_CFG_DATA_WIDTH_8;
		break;
	case 10:
		value |= SUN6I_CSI_IF_CFG_DATA_WIDTH_10;
		break;
	case 12:
		value |= SUN6I_CSI_IF_CFG_DATA_WIDTH_12;
		break;
	default:
		dev_warn(dev, "unsupported bus width: %u\n", bus_width);
		break;
	}

	regmap_write(regmap, SUN6I_CSI_IF_CFG_REG, value);
}

static void
sun6i_csi_bridge_configure_mipi_csi2(struct sun6i_csi_device *csi_dev)
{
	struct regmap *regmap = csi_dev->regmap;
	u32 value = SUN6I_CSI_IF_CFG_IF_MIPI;
	u32 field;

	sun6i_csi_bridge_format(csi_dev, NULL, &field);

	if (field == V4L2_FIELD_INTERLACED ||
	    field == V4L2_FIELD_INTERLACED_TB ||
	    field == V4L2_FIELD_INTERLACED_BT)
		value |= SUN6I_CSI_IF_CFG_SRC_TYPE_INTERLACED;
	else
		value |= SUN6I_CSI_IF_CFG_SRC_TYPE_PROGRESSIVE;

	regmap_write(regmap, SUN6I_CSI_IF_CFG_REG, value);
}

static void sun6i_csi_bridge_configure_format(struct sun6i_csi_device *csi_dev)
{
	struct regmap *regmap = csi_dev->regmap;
	bool capture_streaming = csi_dev->capture.state.streaming;
	const struct sun6i_csi_bridge_format *bridge_format;
	const struct sun6i_csi_capture_format *capture_format;
	u32 mbus_code, field, pixelformat;
	u8 input_format, input_yuv_seq, output_format;
	u32 value = 0;

	sun6i_csi_bridge_format(csi_dev, &mbus_code, &field);

	bridge_format = sun6i_csi_bridge_format_find(mbus_code);
	if (WARN_ON(!bridge_format))
		return;

	input_format = bridge_format->input_format;
	input_yuv_seq = bridge_format->input_yuv_seq;

	if (capture_streaming) {
		sun6i_csi_capture_format(csi_dev, &pixelformat, NULL);

		capture_format = sun6i_csi_capture_format_find(pixelformat);
		if (WARN_ON(!capture_format))
			return;

		if (capture_format->input_format_raw)
			input_format = SUN6I_CSI_INPUT_FMT_RAW;

		if (capture_format->input_yuv_seq_invert)
			input_yuv_seq = bridge_format->input_yuv_seq_invert;

		if (field == V4L2_FIELD_INTERLACED ||
		    field == V4L2_FIELD_INTERLACED_TB ||
		    field == V4L2_FIELD_INTERLACED_BT)
			output_format = capture_format->output_format_field;
		else
			output_format = capture_format->output_format_frame;

		value |= SUN6I_CSI_CH_CFG_OUTPUT_FMT(output_format);
	}

	value |= SUN6I_CSI_CH_CFG_INPUT_FMT(input_format);
	value |= SUN6I_CSI_CH_CFG_INPUT_YUV_SEQ(input_yuv_seq);

	if (field == V4L2_FIELD_TOP)
		value |= SUN6I_CSI_CH_CFG_FIELD_SEL_FIELD0;
	else if (field == V4L2_FIELD_BOTTOM)
		value |= SUN6I_CSI_CH_CFG_FIELD_SEL_FIELD1;
	else
		value |= SUN6I_CSI_CH_CFG_FIELD_SEL_EITHER;

	regmap_write(regmap, SUN6I_CSI_CH_CFG_REG, value);
}

static void sun6i_csi_bridge_configure(struct sun6i_csi_device *csi_dev,
				       struct sun6i_csi_bridge_source *source)
{
	struct sun6i_csi_bridge *bridge = &csi_dev->bridge;

	if (source == &bridge->source_parallel)
		sun6i_csi_bridge_configure_parallel(csi_dev);
	else
		sun6i_csi_bridge_configure_mipi_csi2(csi_dev);

	sun6i_csi_bridge_configure_format(csi_dev);
}

/* V4L2 Subdev */

static int sun6i_csi_bridge_s_stream(struct v4l2_subdev *subdev, int on)
{
	struct sun6i_csi_device *csi_dev = v4l2_get_subdevdata(subdev);
	struct sun6i_csi_bridge *bridge = &csi_dev->bridge;
	struct media_pad *local_pad = &bridge->pads[SUN6I_CSI_BRIDGE_PAD_SINK];
	bool capture_streaming = csi_dev->capture.state.streaming;
	struct device *dev = csi_dev->dev;
	struct sun6i_csi_bridge_source *source;
	struct v4l2_subdev *source_subdev;
	struct media_pad *remote_pad;
	int ret;

	/* Source */

	remote_pad = media_pad_remote_pad_unique(local_pad);
	if (IS_ERR(remote_pad)) {
		dev_err(dev,
			"zero or more than a single source connected to the bridge\n");
		return PTR_ERR(remote_pad);
	}

	source_subdev = media_entity_to_v4l2_subdev(remote_pad->entity);

	if (source_subdev == bridge->source_parallel.subdev)
		source = &bridge->source_parallel;
	else
		source = &bridge->source_mipi_csi2;

	if (!on) {
		v4l2_subdev_call(source_subdev, video, s_stream, 0);
		ret = 0;
		goto disable;
	}

	/* PM */

	ret = pm_runtime_resume_and_get(dev);
	if (ret < 0)
		return ret;

	/* Clear */

	sun6i_csi_bridge_irq_clear(csi_dev);

	/* Configure */

	sun6i_csi_bridge_configure(csi_dev, source);

	if (capture_streaming)
		sun6i_csi_capture_configure(csi_dev);

	/* State Update */

	if (capture_streaming)
		sun6i_csi_capture_state_update(csi_dev);

	/* Enable */

	if (capture_streaming)
		sun6i_csi_bridge_irq_enable(csi_dev);

	sun6i_csi_bridge_enable(csi_dev);

	ret = v4l2_subdev_call(source_subdev, video, s_stream, 1);
	if (ret && ret != -ENOIOCTLCMD)
		goto disable;

	return 0;

disable:
	if (capture_streaming)
		sun6i_csi_bridge_irq_disable(csi_dev);

	sun6i_csi_bridge_disable(csi_dev);

	pm_runtime_put(dev);

	return ret;
}

static const struct v4l2_subdev_video_ops sun6i_csi_bridge_video_ops = {
	.s_stream	= sun6i_csi_bridge_s_stream,
};

static void
sun6i_csi_bridge_mbus_format_prepare(struct v4l2_mbus_framefmt *mbus_format)
{
	if (!sun6i_csi_bridge_format_find(mbus_format->code))
		mbus_format->code = sun6i_csi_bridge_formats[0].mbus_code;

	mbus_format->field = V4L2_FIELD_NONE;
	mbus_format->colorspace = V4L2_COLORSPACE_RAW;
	mbus_format->quantization = V4L2_QUANTIZATION_DEFAULT;
	mbus_format->xfer_func = V4L2_XFER_FUNC_DEFAULT;
}

static int sun6i_csi_bridge_init_cfg(struct v4l2_subdev *subdev,
				     struct v4l2_subdev_state *state)
{
	struct sun6i_csi_device *csi_dev = v4l2_get_subdevdata(subdev);
	unsigned int pad = SUN6I_CSI_BRIDGE_PAD_SINK;
	struct v4l2_mbus_framefmt *mbus_format =
		v4l2_subdev_get_try_format(subdev, state, pad);
	struct mutex *lock = &csi_dev->bridge.lock;

	mutex_lock(lock);

	mbus_format->code = sun6i_csi_bridge_formats[0].mbus_code;
	mbus_format->width = 1280;
	mbus_format->height = 720;

	sun6i_csi_bridge_mbus_format_prepare(mbus_format);

	mutex_unlock(lock);

	return 0;
}

static int
sun6i_csi_bridge_enum_mbus_code(struct v4l2_subdev *subdev,
				struct v4l2_subdev_state *state,
				struct v4l2_subdev_mbus_code_enum *code_enum)
{
	if (code_enum->index >= ARRAY_SIZE(sun6i_csi_bridge_formats))
		return -EINVAL;

	code_enum->code = sun6i_csi_bridge_formats[code_enum->index].mbus_code;

	return 0;
}

static int sun6i_csi_bridge_get_fmt(struct v4l2_subdev *subdev,
				    struct v4l2_subdev_state *state,
				    struct v4l2_subdev_format *format)
{
	struct sun6i_csi_device *csi_dev = v4l2_get_subdevdata(subdev);
	struct v4l2_mbus_framefmt *mbus_format = &format->format;
	struct mutex *lock = &csi_dev->bridge.lock;

	mutex_lock(lock);

	if (format->which == V4L2_SUBDEV_FORMAT_TRY)
		*mbus_format = *v4l2_subdev_get_try_format(subdev, state,
							   format->pad);
	else
		*mbus_format = csi_dev->bridge.mbus_format;

	mutex_unlock(lock);

	return 0;
}

static int sun6i_csi_bridge_set_fmt(struct v4l2_subdev *subdev,
				    struct v4l2_subdev_state *state,
				    struct v4l2_subdev_format *format)
{
	struct sun6i_csi_device *csi_dev = v4l2_get_subdevdata(subdev);
	struct v4l2_mbus_framefmt *mbus_format = &format->format;
	struct mutex *lock = &csi_dev->bridge.lock;

	mutex_lock(lock);

	sun6i_csi_bridge_mbus_format_prepare(mbus_format);

	if (format->which == V4L2_SUBDEV_FORMAT_TRY)
		*v4l2_subdev_get_try_format(subdev, state, format->pad) =
			*mbus_format;
	else
		csi_dev->bridge.mbus_format = *mbus_format;

	mutex_unlock(lock);

	return 0;
}

static const struct v4l2_subdev_pad_ops sun6i_csi_bridge_pad_ops = {
	.init_cfg	= sun6i_csi_bridge_init_cfg,
	.enum_mbus_code	= sun6i_csi_bridge_enum_mbus_code,
	.get_fmt	= sun6i_csi_bridge_get_fmt,
	.set_fmt	= sun6i_csi_bridge_set_fmt,
};

static const struct v4l2_subdev_ops sun6i_csi_bridge_subdev_ops = {
	.video	= &sun6i_csi_bridge_video_ops,
	.pad	= &sun6i_csi_bridge_pad_ops,
};

/* Media Entity */

static const struct media_entity_operations sun6i_csi_bridge_entity_ops = {
	.link_validate	= v4l2_subdev_link_validate,
};

/* V4L2 Async */

static int sun6i_csi_bridge_link(struct sun6i_csi_device *csi_dev,
				 int sink_pad_index,
				 struct v4l2_subdev *remote_subdev,
				 bool enabled)
{
	struct device *dev = csi_dev->dev;
	struct v4l2_subdev *subdev = &csi_dev->bridge.subdev;
	struct media_entity *sink_entity = &subdev->entity;
	struct media_entity *source_entity = &remote_subdev->entity;
	int source_pad_index;
	int ret;

	/* Get the first remote source pad. */
	ret = media_entity_get_fwnode_pad(source_entity, remote_subdev->fwnode,
					  MEDIA_PAD_FL_SOURCE);
	if (ret < 0) {
		dev_err(dev, "missing source pad in external entity %s\n",
			source_entity->name);
		return -EINVAL;
	}

	source_pad_index = ret;

	dev_dbg(dev, "creating %s:%u -> %s:%u link\n", source_entity->name,
		source_pad_index, sink_entity->name, sink_pad_index);

	ret = media_create_pad_link(source_entity, source_pad_index,
				    sink_entity, sink_pad_index,
				    enabled ? MEDIA_LNK_FL_ENABLED : 0);
	if (ret < 0) {
		dev_err(dev, "failed to create %s:%u -> %s:%u link\n",
			source_entity->name, source_pad_index,
			sink_entity->name, sink_pad_index);
		return ret;
	}

	return 0;
}

static int
sun6i_csi_bridge_notifier_bound(struct v4l2_async_notifier *notifier,
				struct v4l2_subdev *remote_subdev,
				struct v4l2_async_subdev *async_subdev)
{
	struct sun6i_csi_device *csi_dev =
		container_of(notifier, struct sun6i_csi_device,
			     bridge.notifier);
	struct sun6i_csi_bridge_async_subdev *bridge_async_subdev =
		container_of(async_subdev, struct sun6i_csi_bridge_async_subdev,
			     async_subdev);
	struct sun6i_csi_bridge *bridge = &csi_dev->bridge;
	struct sun6i_csi_bridge_source *source = bridge_async_subdev->source;
	bool enabled = false;
	int ret;

	switch (source->endpoint.base.port) {
	case SUN6I_CSI_PORT_PARALLEL:
		enabled = true;
		break;
	case SUN6I_CSI_PORT_MIPI_CSI2:
		enabled = !bridge->source_parallel.expected;
		break;
	default:
		return -EINVAL;
	}

	source->subdev = remote_subdev;

	if (csi_dev->isp_available) {
		/*
		 * Hook to the first available remote subdev to get v4l2 and
		 * media devices and register the capture device then.
		 */
		ret = sun6i_csi_isp_complete(csi_dev, remote_subdev->v4l2_dev);
		if (ret)
			return ret;
	}

	return sun6i_csi_bridge_link(csi_dev, SUN6I_CSI_BRIDGE_PAD_SINK,
				     remote_subdev, enabled);
}

static int
sun6i_csi_bridge_notifier_complete(struct v4l2_async_notifier *notifier)
{
	struct sun6i_csi_device *csi_dev =
		container_of(notifier, struct sun6i_csi_device,
			     bridge.notifier);
	struct v4l2_device *v4l2_dev = &csi_dev->v4l2.v4l2_dev;

	if (csi_dev->isp_available)
		return 0;

	return v4l2_device_register_subdev_nodes(v4l2_dev);
}

static const struct v4l2_async_notifier_operations
sun6i_csi_bridge_notifier_ops = {
	.bound		= sun6i_csi_bridge_notifier_bound,
	.complete	= sun6i_csi_bridge_notifier_complete,
};

/* Bridge */

static int sun6i_csi_bridge_source_setup(struct sun6i_csi_device *csi_dev,
					 struct sun6i_csi_bridge_source *source,
					 u32 port,
					 enum v4l2_mbus_type *bus_types)
{
	struct device *dev = csi_dev->dev;
	struct v4l2_async_notifier *notifier = &csi_dev->bridge.notifier;
	struct v4l2_fwnode_endpoint *endpoint = &source->endpoint;
	struct sun6i_csi_bridge_async_subdev *bridge_async_subdev;
	struct fwnode_handle *handle;
	int ret;

	handle = fwnode_graph_get_endpoint_by_id(dev_fwnode(dev), port, 0, 0);
	if (!handle)
		return -ENODEV;

	ret = v4l2_fwnode_endpoint_parse(handle, endpoint);
	if (ret)
		goto complete;

	if (bus_types) {
		bool valid = false;
		unsigned int i;

		for (i = 0; bus_types[i] != V4L2_MBUS_INVALID; i++) {
			if (endpoint->bus_type == bus_types[i]) {
				valid = true;
				break;
			}
		}

		if (!valid) {
			dev_err(dev, "unsupported bus type for port %d\n",
				port);
			ret = -EINVAL;
			goto complete;
		}
	}

	bridge_async_subdev =
		v4l2_async_nf_add_fwnode_remote(notifier, handle,
						struct
						sun6i_csi_bridge_async_subdev);
	if (IS_ERR(bridge_async_subdev)) {
		ret = PTR_ERR(bridge_async_subdev);
		goto complete;
	}

	bridge_async_subdev->source = source;

	source->expected = true;

complete:
	fwnode_handle_put(handle);

	return ret;
}

int sun6i_csi_bridge_setup(struct sun6i_csi_device *csi_dev)
{
	struct device *dev = csi_dev->dev;
	struct sun6i_csi_bridge *bridge = &csi_dev->bridge;
	struct v4l2_device *v4l2_dev = csi_dev->v4l2_dev;
	struct v4l2_subdev *subdev = &bridge->subdev;
	struct v4l2_async_notifier *notifier = &bridge->notifier;
	struct media_pad *pads = bridge->pads;
	enum v4l2_mbus_type parallel_mbus_types[] = {
		V4L2_MBUS_PARALLEL,
		V4L2_MBUS_BT656,
		V4L2_MBUS_INVALID
	};
	int ret;

	mutex_init(&bridge->lock);

	/* V4L2 Subdev */

	v4l2_subdev_init(subdev, &sun6i_csi_bridge_subdev_ops);
	strscpy(subdev->name, SUN6I_CSI_BRIDGE_NAME, sizeof(subdev->name));
	subdev->flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
	subdev->owner = THIS_MODULE;
	subdev->dev = dev;

	v4l2_set_subdevdata(subdev, csi_dev);

	/* Media Entity */

	subdev->entity.function = MEDIA_ENT_F_VID_IF_BRIDGE;
	subdev->entity.ops = &sun6i_csi_bridge_entity_ops;

	/* Media Pads */

	pads[SUN6I_CSI_BRIDGE_PAD_SINK].flags = MEDIA_PAD_FL_SINK;
	pads[SUN6I_CSI_BRIDGE_PAD_SOURCE].flags = MEDIA_PAD_FL_SOURCE |
						  MEDIA_PAD_FL_MUST_CONNECT;

	ret = media_entity_pads_init(&subdev->entity,
				     SUN6I_CSI_BRIDGE_PAD_COUNT, pads);
	if (ret < 0)
		return ret;

	/* V4L2 Subdev */

	if (csi_dev->isp_available)
		ret = v4l2_async_register_subdev(subdev);
	else
		ret = v4l2_device_register_subdev(v4l2_dev, subdev);

	if (ret) {
		dev_err(dev, "failed to register v4l2 subdev: %d\n", ret);
		goto error_media_entity;
	}

	/* V4L2 Async */

	v4l2_async_nf_init(notifier);
	notifier->ops = &sun6i_csi_bridge_notifier_ops;

	sun6i_csi_bridge_source_setup(csi_dev, &bridge->source_parallel,
				      SUN6I_CSI_PORT_PARALLEL,
				      parallel_mbus_types);
	sun6i_csi_bridge_source_setup(csi_dev, &bridge->source_mipi_csi2,
				      SUN6I_CSI_PORT_MIPI_CSI2, NULL);

	if (csi_dev->isp_available)
		ret = v4l2_async_subdev_nf_register(subdev, notifier);
	else
		ret = v4l2_async_nf_register(v4l2_dev, notifier);
	if (ret) {
		dev_err(dev, "failed to register v4l2 async notifier: %d\n",
			ret);
		goto error_v4l2_async_notifier;
	}

	return 0;

error_v4l2_async_notifier:
	v4l2_async_nf_cleanup(notifier);

	if (csi_dev->isp_available)
		v4l2_async_unregister_subdev(subdev);
	else
		v4l2_device_unregister_subdev(subdev);

error_media_entity:
	media_entity_cleanup(&subdev->entity);

	return ret;
}

void sun6i_csi_bridge_cleanup(struct sun6i_csi_device *csi_dev)
{
	struct v4l2_subdev *subdev = &csi_dev->bridge.subdev;
	struct v4l2_async_notifier *notifier = &csi_dev->bridge.notifier;

	v4l2_async_nf_unregister(notifier);
	v4l2_async_nf_cleanup(notifier);

	v4l2_device_unregister_subdev(subdev);

	media_entity_cleanup(&subdev->entity);
}