Add driver for TI DS90UB913 FPD-Link III Serializer.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 drivers/media/i2c/Kconfig     |  13 +
 drivers/media/i2c/Makefile    |   1 +
 drivers/media/i2c/ds90ub913.c | 906 ++++++++++++++++++++++++++++++++++
 3 files changed, 920 insertions(+)
 create mode 100644 drivers/media/i2c/ds90ub913.c

diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
index 60eafa1f5681..31d46e0bfbcf 100644
--- a/drivers/media/i2c/Kconfig
+++ b/drivers/media/i2c/Kconfig
@@ -1630,6 +1630,19 @@ endmenu
 
 menu "Video serializers and deserializers"
 
+config VIDEO_DS90UB913
+	tristate "TI DS90UB913 FPD-Link III Serializer"
+	depends on OF && I2C && VIDEO_DEV && COMMON_CLK
+	select I2C_ATR
+	select MEDIA_CONTROLLER
+	select GPIOLIB
+	select REGMAP_I2C
+	select V4L2_FWNODE
+	select VIDEO_V4L2_SUBDEV_API
+	help
+	  Device driver for the Texas Instruments DS90UB913
+	  FPD-Link III Serializer.
+
 config VIDEO_DS90UB960
 	tristate "TI FPD-Link III/IV Deserializers"
 	depends on OF && I2C && VIDEO_DEV && COMMON_CLK
diff --git a/drivers/media/i2c/Makefile b/drivers/media/i2c/Makefile
index 0da487e35022..c2507520e01c 100644
--- a/drivers/media/i2c/Makefile
+++ b/drivers/media/i2c/Makefile
@@ -28,6 +28,7 @@ obj-$(CONFIG_VIDEO_CS3308) += cs3308.o
 obj-$(CONFIG_VIDEO_CS5345) += cs5345.o
 obj-$(CONFIG_VIDEO_CS53L32A) += cs53l32a.o
 obj-$(CONFIG_VIDEO_CX25840) += cx25840/
+obj-$(CONFIG_VIDEO_DS90UB913) += ds90ub913.o
 obj-$(CONFIG_VIDEO_DS90UB960) += ds90ub960.o
 obj-$(CONFIG_VIDEO_DW9714) += dw9714.o
 obj-$(CONFIG_VIDEO_DW9768) += dw9768.o
diff --git a/drivers/media/i2c/ds90ub913.c b/drivers/media/i2c/ds90ub913.c
new file mode 100644
index 000000000000..203f7cceae23
--- /dev/null
+++ b/drivers/media/i2c/ds90ub913.c
@@ -0,0 +1,906 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Driver for the Texas Instruments DS90UB913 video serializer
+ *
+ * Based on a driver from Luca Ceresoli <luca@lucaceresoli.net>
+ *
+ * Copyright (c) 2019 Luca Ceresoli <luca@lucaceresoli.net>
+ * Copyright (c) 2023 Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/fwnode.h>
+#include <linux/gpio/driver.h>
+#include <linux/i2c-atr.h>
+#include <linux/i2c.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/property.h>
+#include <linux/regmap.h>
+
+#include <media/i2c/ds90ub9xx.h>
+#include <media/v4l2-subdev.h>
+
+#define UB913_PAD_SINK			0
+#define UB913_PAD_SOURCE		1
+
+/*
+ * UB913 has 4 gpios, but gpios 3 and 4 are reserved for external oscillator
+ * mode. Thus we only support 2 gpios for now.
+ */
+#define UB913_NUM_GPIOS			2
+
+#define UB913_REG_RESET_CTL			0x01
+#define UB913_REG_RESET_CTL_DIGITAL_RESET_1	BIT(1)
+#define UB913_REG_RESET_CTL_DIGITAL_RESET_0	BIT(0)
+
+#define UB913_REG_GENERAL_CFG			0x03
+#define UB913_REG_GENERAL_CFG_CRC_ERR_RESET	BIT(5)
+#define UB913_REG_GENERAL_CFG_PCLK_RISING	BIT(0)
+
+#define UB913_REG_MODE_SEL			0x05
+#define UB913_REG_MODE_SEL_MODE_OVERRIDE	BIT(5)
+#define UB913_REG_MODE_SEL_MODE_UP_TO_DATE	BIT(4)
+#define UB913_REG_MODE_SEL_MODE_MASK		GENMASK(3, 0)
+
+#define UB913_REG_CRC_ERRORS_LSB		0x0a
+#define UB913_REG_CRC_ERRORS_MSB		0x0b
+
+#define UB913_REG_GENERAL_STATUS		0x0c
+
+#define UB913_REG_GPIO_CFG(n)			(0x0d + (n))
+#define UB913_REG_GPIO_CFG_ENABLE(n)		BIT(0 + (n) * 4)
+#define UB913_REG_GPIO_CFG_DIR_INPUT(n)		BIT(1 + (n) * 4)
+#define UB913_REG_GPIO_CFG_REMOTE_EN(n)		BIT(2 + (n) * 4)
+#define UB913_REG_GPIO_CFG_OUT_VAL(n)		BIT(3 + (n) * 4)
+#define UB913_REG_GPIO_CFG_MASK(n)		(0xf << ((n) * 4))
+
+#define UB913_REG_SCL_HIGH_TIME			0x11
+#define UB913_REG_SCL_LOW_TIME			0x12
+
+#define UB913_REG_PLL_OVR			0x35
+
+struct ub913_data {
+	struct i2c_client	*client;
+	struct regmap		*regmap;
+	struct clk		*clkin;
+
+	struct gpio_chip	gpio_chip;
+
+	struct v4l2_subdev	sd;
+	struct media_pad	pads[2];
+
+	struct v4l2_async_notifier	notifier;
+
+	struct v4l2_subdev	*source_sd;
+	u16			source_sd_pad;
+
+	u64			enabled_source_streams;
+
+	struct clk_hw		*clkout_clk_hw;
+
+	struct ds90ub9xx_platform_data *plat_data;
+
+	u32			pclk_polarity;
+};
+
+static inline struct ub913_data *sd_to_ub913(struct v4l2_subdev *sd)
+{
+	return container_of(sd, struct ub913_data, sd);
+}
+
+struct ub913_format_info {
+	u32 incode;
+	u32 outcode;
+};
+
+static const struct ub913_format_info ub913_formats[] = {
+	/* Only RAW10 with 8-bit payload is supported at the moment */
+	{ .incode = MEDIA_BUS_FMT_YUYV8_2X8, .outcode = MEDIA_BUS_FMT_YUYV8_1X16 },
+	{ .incode = MEDIA_BUS_FMT_UYVY8_2X8, .outcode = MEDIA_BUS_FMT_UYVY8_1X16 },
+	{ .incode = MEDIA_BUS_FMT_VYUY8_2X8, .outcode = MEDIA_BUS_FMT_VYUY8_1X16 },
+	{ .incode = MEDIA_BUS_FMT_YVYU8_2X8, .outcode = MEDIA_BUS_FMT_YVYU8_1X16 },
+};
+
+static const struct ub913_format_info *ub913_find_format(u32 incode)
+{
+	unsigned int i;
+
+	for (i = 0; i < ARRAY_SIZE(ub913_formats); i++) {
+		if (ub913_formats[i].incode == incode)
+			return &ub913_formats[i];
+	}
+
+	return NULL;
+}
+
+static int ub913_read(const struct ub913_data *priv, u8 reg, u8 *val)
+{
+	unsigned int v;
+	int ret;
+
+	ret = regmap_read(priv->regmap, reg, &v);
+	if (ret < 0) {
+		dev_err(&priv->client->dev,
+			"Cannot read register 0x%02x: %d!\n", reg, ret);
+		return ret;
+	}
+
+	*val = v;
+	return 0;
+}
+
+static int ub913_write(const struct ub913_data *priv, u8 reg, u8 val)
+{
+	int ret;
+
+	ret = regmap_write(priv->regmap, reg, val);
+	if (ret < 0)
+		dev_err(&priv->client->dev,
+			"Cannot write register 0x%02x: %d!\n", reg, ret);
+
+	return ret;
+}
+
+/*
+ * GPIO chip
+ */
+static int ub913_gpio_get_direction(struct gpio_chip *gc, unsigned int offset)
+{
+	return GPIO_LINE_DIRECTION_OUT;
+}
+
+static int ub913_gpio_direction_out(struct gpio_chip *gc, unsigned int offset,
+				    int value)
+{
+	struct ub913_data *priv = gpiochip_get_data(gc);
+	unsigned int reg_idx = offset / 2;
+	unsigned int field_idx = offset % 2;
+
+	return regmap_update_bits(priv->regmap, UB913_REG_GPIO_CFG(reg_idx),
+				  UB913_REG_GPIO_CFG_MASK(field_idx),
+				  UB913_REG_GPIO_CFG_ENABLE(field_idx) |
+					  (value ? UB913_REG_GPIO_CFG_OUT_VAL(field_idx) :
+						   0));
+}
+
+static void ub913_gpio_set(struct gpio_chip *gc, unsigned int offset, int value)
+{
+	ub913_gpio_direction_out(gc, offset, value);
+}
+
+static int ub913_gpio_of_xlate(struct gpio_chip *gc,
+			       const struct of_phandle_args *gpiospec,
+			       u32 *flags)
+{
+	if (flags)
+		*flags = gpiospec->args[1];
+
+	return gpiospec->args[0];
+}
+
+static int ub913_gpiochip_probe(struct ub913_data *priv)
+{
+	struct device *dev = &priv->client->dev;
+	struct gpio_chip *gc = &priv->gpio_chip;
+	int ret;
+
+	/* Initialize GPIOs 0 and 1 to local control, tri-state */
+	ub913_write(priv, UB913_REG_GPIO_CFG(0), 0);
+
+	gc->label = dev_name(dev);
+	gc->parent = dev;
+	gc->owner = THIS_MODULE;
+	gc->base = -1;
+	gc->can_sleep = true;
+	gc->ngpio = UB913_NUM_GPIOS;
+	gc->get_direction = ub913_gpio_get_direction;
+	gc->direction_output = ub913_gpio_direction_out;
+	gc->set = ub913_gpio_set;
+	gc->of_xlate = ub913_gpio_of_xlate;
+	gc->of_gpio_n_cells = 2;
+
+	ret = gpiochip_add_data(gc, priv);
+	if (ret) {
+		dev_err(dev, "Failed to add GPIOs: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static void ub913_gpiochip_remove(struct ub913_data *priv)
+{
+	gpiochip_remove(&priv->gpio_chip);
+}
+
+static const struct regmap_config ub913_regmap_config = {
+	.name = "ds90ub913",
+	.reg_bits = 8,
+	.val_bits = 8,
+	.reg_format_endian = REGMAP_ENDIAN_DEFAULT,
+	.val_format_endian = REGMAP_ENDIAN_DEFAULT,
+};
+
+/*
+ * V4L2
+ */
+
+static int ub913_enable_streams(struct v4l2_subdev *sd,
+				struct v4l2_subdev_state *state, u32 pad,
+				u64 streams_mask)
+{
+	struct ub913_data *priv = sd_to_ub913(sd);
+	u64 sink_streams;
+	int ret;
+
+	sink_streams = v4l2_subdev_state_xlate_streams(state, UB913_PAD_SOURCE,
+						       UB913_PAD_SINK,
+						       &streams_mask);
+
+	ret = v4l2_subdev_enable_streams(priv->source_sd, priv->source_sd_pad,
+					 sink_streams);
+	if (ret)
+		return ret;
+
+	priv->enabled_source_streams |= streams_mask;
+
+	return 0;
+}
+
+static int ub913_disable_streams(struct v4l2_subdev *sd,
+				 struct v4l2_subdev_state *state, u32 pad,
+				 u64 streams_mask)
+{
+	struct ub913_data *priv = sd_to_ub913(sd);
+	u64 sink_streams;
+	int ret;
+
+	sink_streams = v4l2_subdev_state_xlate_streams(state, UB913_PAD_SOURCE,
+						       UB913_PAD_SINK,
+						       &streams_mask);
+
+	ret = v4l2_subdev_disable_streams(priv->source_sd, priv->source_sd_pad,
+					  sink_streams);
+	if (ret)
+		return ret;
+
+	priv->enabled_source_streams &= ~streams_mask;
+
+	return 0;
+}
+
+static int _ub913_set_routing(struct v4l2_subdev *sd,
+			      struct v4l2_subdev_state *state,
+			      struct v4l2_subdev_krouting *routing)
+{
+	static const struct v4l2_mbus_framefmt in_format = {
+		.width = 640,
+		.height = 480,
+		.code = MEDIA_BUS_FMT_UYVY8_2X8,
+		.field = V4L2_FIELD_NONE,
+		.colorspace = V4L2_COLORSPACE_SRGB,
+		.ycbcr_enc = V4L2_YCBCR_ENC_601,
+		.quantization = V4L2_QUANTIZATION_LIM_RANGE,
+		.xfer_func = V4L2_XFER_FUNC_SRGB,
+	};
+	static const struct v4l2_mbus_framefmt out_format = {
+		.width = 640,
+		.height = 480,
+		.code = MEDIA_BUS_FMT_UYVY8_1X16,
+		.field = V4L2_FIELD_NONE,
+		.colorspace = V4L2_COLORSPACE_SRGB,
+		.ycbcr_enc = V4L2_YCBCR_ENC_601,
+		.quantization = V4L2_QUANTIZATION_LIM_RANGE,
+		.xfer_func = V4L2_XFER_FUNC_SRGB,
+	};
+	struct v4l2_subdev_stream_configs *stream_configs;
+	unsigned int i;
+	int ret;
+
+	/*
+	 * Note: we can only support up to V4L2_FRAME_DESC_ENTRY_MAX, until
+	 * frame desc is made dynamically allocated.
+	 */
+
+	if (routing->num_routes > V4L2_FRAME_DESC_ENTRY_MAX)
+		return -EINVAL;
+
+	ret = v4l2_subdev_routing_validate(sd, routing,
+					   V4L2_SUBDEV_ROUTING_ONLY_1_TO_1);
+	if (ret)
+		return ret;
+
+	ret = v4l2_subdev_set_routing(sd, state, routing);
+	if (ret)
+		return ret;
+
+	stream_configs = &state->stream_configs;
+
+	for (i = 0; i < stream_configs->num_configs; i++) {
+		if (stream_configs->configs[i].pad == UB913_PAD_SINK)
+			stream_configs->configs[i].fmt = in_format;
+		else
+			stream_configs->configs[i].fmt = out_format;
+	}
+
+	return 0;
+}
+
+static int ub913_set_routing(struct v4l2_subdev *sd,
+			     struct v4l2_subdev_state *state,
+			     enum v4l2_subdev_format_whence which,
+			     struct v4l2_subdev_krouting *routing)
+{
+	struct ub913_data *priv = sd_to_ub913(sd);
+
+	if (which == V4L2_SUBDEV_FORMAT_ACTIVE && priv->enabled_source_streams)
+		return -EBUSY;
+
+	return _ub913_set_routing(sd, state, routing);
+}
+
+static int ub913_get_frame_desc(struct v4l2_subdev *sd, unsigned int pad,
+				struct v4l2_mbus_frame_desc *fd)
+{
+	struct ub913_data *priv = sd_to_ub913(sd);
+	const struct v4l2_subdev_krouting *routing;
+	struct v4l2_mbus_frame_desc source_fd;
+	struct v4l2_subdev_route *route;
+	struct v4l2_subdev_state *state;
+	int ret;
+
+	if (pad != UB913_PAD_SOURCE)
+		return -EINVAL;
+
+	ret = v4l2_subdev_call(priv->source_sd, pad, get_frame_desc,
+			       priv->source_sd_pad, &source_fd);
+	if (ret)
+		return ret;
+
+	memset(fd, 0, sizeof(*fd));
+
+	fd->type = V4L2_MBUS_FRAME_DESC_TYPE_PARALLEL;
+
+	state = v4l2_subdev_lock_and_get_active_state(sd);
+
+	routing = &state->routing;
+
+	for_each_active_route(routing, route) {
+		unsigned int i;
+
+		if (route->source_pad != pad)
+			continue;
+
+		for (i = 0; i < source_fd.num_entries; i++) {
+			if (source_fd.entry[i].stream == route->sink_stream)
+				break;
+		}
+
+		if (i == source_fd.num_entries) {
+			dev_err(&priv->client->dev,
+				"Failed to find stream from source frame desc\n");
+			ret = -EPIPE;
+			goto out_unlock;
+		}
+
+		fd->entry[fd->num_entries].stream = route->source_stream;
+		fd->entry[fd->num_entries].flags = source_fd.entry[i].flags;
+		fd->entry[fd->num_entries].length = source_fd.entry[i].length;
+		fd->entry[fd->num_entries].pixelcode =
+			source_fd.entry[i].pixelcode;
+
+		fd->num_entries++;
+	}
+
+out_unlock:
+	v4l2_subdev_unlock_state(state);
+
+	return ret;
+}
+
+static int ub913_set_fmt(struct v4l2_subdev *sd,
+			 struct v4l2_subdev_state *state,
+			 struct v4l2_subdev_format *format)
+{
+	struct ub913_data *priv = sd_to_ub913(sd);
+	struct v4l2_mbus_framefmt *fmt;
+	const struct ub913_format_info *finfo;
+
+	if (format->which == V4L2_SUBDEV_FORMAT_ACTIVE &&
+	    priv->enabled_source_streams)
+		return -EBUSY;
+
+	/* Source format is fully defined by the sink format, so not settable */
+	if (format->pad == UB913_PAD_SOURCE)
+		return v4l2_subdev_get_fmt(sd, state, format);
+
+	finfo = ub913_find_format(format->format.code);
+	if (!finfo) {
+		finfo = &ub913_formats[0];
+		format->format.code = finfo->incode;
+	}
+
+	/* Set sink format */
+	fmt = v4l2_subdev_state_get_stream_format(state, format->pad,
+						  format->stream);
+	if (!fmt)
+		return -EINVAL;
+
+	*fmt = format->format;
+
+	/* Propagate to source format, and adjust the mbus code */
+	fmt = v4l2_subdev_state_get_opposite_stream_format(state, format->pad,
+							   format->stream);
+	if (!fmt)
+		return -EINVAL;
+
+	format->format.code = finfo->outcode;
+
+	*fmt = format->format;
+
+	return 0;
+}
+
+static int ub913_init_cfg(struct v4l2_subdev *sd,
+			  struct v4l2_subdev_state *state)
+{
+	struct v4l2_subdev_route routes[] = {
+		{
+			.sink_pad = UB913_PAD_SINK,
+			.sink_stream = 0,
+			.source_pad = UB913_PAD_SOURCE,
+			.source_stream = 0,
+			.flags = V4L2_SUBDEV_ROUTE_FL_ACTIVE,
+		},
+	};
+
+	struct v4l2_subdev_krouting routing = {
+		.num_routes = ARRAY_SIZE(routes),
+		.routes = routes,
+	};
+
+	return _ub913_set_routing(sd, state, &routing);
+}
+
+static int ub913_log_status(struct v4l2_subdev *sd)
+{
+	struct ub913_data *priv = sd_to_ub913(sd);
+	struct device *dev = &priv->client->dev;
+	u8 v, v1, v2;
+
+	ub913_read(priv, UB913_REG_MODE_SEL, &v);
+	dev_info(dev, "MODE_SEL %#02x\n", v);
+
+	ub913_read(priv, UB913_REG_CRC_ERRORS_LSB, &v1);
+	ub913_read(priv, UB913_REG_CRC_ERRORS_MSB, &v2);
+	dev_info(dev, "CRC errors %u\n", v1 | (v2 << 8));
+
+	/* clear CRC errors */
+	ub913_read(priv, UB913_REG_GENERAL_CFG, &v);
+	ub913_write(priv, UB913_REG_GENERAL_CFG,
+		    v | UB913_REG_GENERAL_CFG_CRC_ERR_RESET);
+	ub913_write(priv, UB913_REG_GENERAL_CFG, v);
+
+	ub913_read(priv, UB913_REG_GENERAL_STATUS, &v);
+	dev_info(dev, "GENERAL_STATUS %#02x\n", v);
+
+	ub913_read(priv, UB913_REG_PLL_OVR, &v);
+	dev_info(dev, "PLL_OVR %#02x\n", v);
+
+	return 0;
+}
+
+static const struct v4l2_subdev_core_ops ub913_subdev_core_ops = {
+	.log_status = ub913_log_status,
+};
+
+static const struct v4l2_subdev_pad_ops ub913_pad_ops = {
+	.enable_streams = ub913_enable_streams,
+	.disable_streams = ub913_disable_streams,
+	.set_routing = ub913_set_routing,
+	.get_frame_desc = ub913_get_frame_desc,
+	.get_fmt = v4l2_subdev_get_fmt,
+	.set_fmt = ub913_set_fmt,
+	.init_cfg = ub913_init_cfg,
+};
+
+static const struct v4l2_subdev_ops ub913_subdev_ops = {
+	.core = &ub913_subdev_core_ops,
+	.pad = &ub913_pad_ops,
+};
+
+static const struct media_entity_operations ub913_entity_ops = {
+	.link_validate = v4l2_subdev_link_validate,
+};
+
+static int ub913_notify_bound(struct v4l2_async_notifier *notifier,
+			      struct v4l2_subdev *source_subdev,
+			      struct v4l2_async_subdev *asd)
+{
+	struct ub913_data *priv = sd_to_ub913(notifier->sd);
+	struct device *dev = &priv->client->dev;
+	int ret;
+
+	ret = media_entity_get_fwnode_pad(&source_subdev->entity,
+					  source_subdev->fwnode,
+					  MEDIA_PAD_FL_SOURCE);
+	if (ret < 0) {
+		dev_err(dev, "Failed to find pad for %s\n",
+			source_subdev->name);
+		return ret;
+	}
+
+	priv->source_sd = source_subdev;
+	priv->source_sd_pad = ret;
+
+	ret = media_create_pad_link(&source_subdev->entity, priv->source_sd_pad,
+				    &priv->sd.entity, UB913_PAD_SINK,
+				    MEDIA_LNK_FL_ENABLED |
+					    MEDIA_LNK_FL_IMMUTABLE);
+	if (ret) {
+		dev_err(dev, "Unable to link %s:%u -> %s:0\n",
+			source_subdev->name, priv->source_sd_pad,
+			priv->sd.name);
+		return ret;
+	}
+
+	return 0;
+}
+
+static const struct v4l2_async_notifier_operations ub913_notify_ops = {
+	.bound = ub913_notify_bound,
+};
+
+static int ub913_v4l2_notifier_register(struct ub913_data *priv)
+{
+	struct device *dev = &priv->client->dev;
+	struct v4l2_async_subdev *asd;
+	struct fwnode_handle *ep_fwnode;
+	int ret;
+
+	ep_fwnode = fwnode_graph_get_endpoint_by_id(dev_fwnode(dev),
+						    UB913_PAD_SINK, 0, 0);
+	if (!ep_fwnode) {
+		dev_err(dev, "No graph endpoint\n");
+		return -ENODEV;
+	}
+
+	v4l2_async_nf_init(&priv->notifier);
+
+	asd = v4l2_async_nf_add_fwnode_remote(&priv->notifier, ep_fwnode,
+					      struct v4l2_async_subdev);
+
+	fwnode_handle_put(ep_fwnode);
+
+	if (IS_ERR(asd)) {
+		dev_err(dev, "Failed to add subdev: %ld", PTR_ERR(asd));
+		v4l2_async_nf_cleanup(&priv->notifier);
+		return PTR_ERR(asd);
+	}
+
+	priv->notifier.ops = &ub913_notify_ops;
+
+	ret = v4l2_async_subdev_nf_register(&priv->sd, &priv->notifier);
+	if (ret) {
+		dev_err(dev, "Failed to register subdev_notifier");
+		v4l2_async_nf_cleanup(&priv->notifier);
+		return ret;
+	}
+
+	return 0;
+}
+
+static void ub913_v4l2_nf_unregister(struct ub913_data *priv)
+{
+	v4l2_async_nf_unregister(&priv->notifier);
+	v4l2_async_nf_cleanup(&priv->notifier);
+}
+
+static int ub913_register_clkout(struct ub913_data *priv)
+{
+	struct device *dev = &priv->client->dev;
+	const char *name;
+	int ret;
+
+	name = kasprintf(GFP_KERNEL, "ds90ub913.%s.clk_out", dev_name(dev));
+	if (!name)
+		return -ENOMEM;
+
+	priv->clkout_clk_hw = devm_clk_hw_register_fixed_factor(dev, name,
+		__clk_get_name(priv->clkin), 0, 1, 2);
+
+	kfree(name);
+
+	if (IS_ERR(priv->clkout_clk_hw))
+		return dev_err_probe(dev, PTR_ERR(priv->clkout_clk_hw),
+				     "Cannot register clkout hw\n");
+
+	ret = devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get,
+					  priv->clkout_clk_hw);
+	if (ret)
+		return dev_err_probe(dev, ret,
+				     "Cannot add OF clock provider\n");
+
+	return 0;
+}
+
+static int ub913_i2c_master_init(struct ub913_data *priv)
+{
+	/* i2c fast mode */
+	u32 scl_high = 600 + 300; /* high period + rise time, ns */
+	u32 scl_low = 1300 + 300; /* low period + fall time, ns */
+	unsigned long ref;
+	int ret;
+
+	ref = clk_get_rate(priv->clkin) / 2;
+
+	scl_high = div64_u64((u64)scl_high * ref, 1000000000);
+	scl_low = div64_u64((u64)scl_low * ref, 1000000000);
+
+	ret = ub913_write(priv, UB913_REG_SCL_HIGH_TIME, scl_high);
+	if (ret)
+		return ret;
+
+	ret = ub913_write(priv, UB913_REG_SCL_LOW_TIME, scl_low);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static int ub913_add_i2c_adapter(struct ub913_data *priv)
+{
+	struct device *dev = &priv->client->dev;
+	struct fwnode_handle *i2c_handle;
+	int ret;
+
+	i2c_handle = device_get_named_child_node(dev, "i2c");
+	if (!i2c_handle)
+		return 0;
+
+	ret = i2c_atr_add_adapter(priv->plat_data->atr, priv->plat_data->port,
+				  dev, i2c_handle);
+
+	fwnode_handle_put(i2c_handle);
+
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static int ub913_parse_dt(struct ub913_data *priv)
+{
+	struct device *dev = &priv->client->dev;
+	struct fwnode_handle *ep_fwnode;
+	int ret;
+
+	ep_fwnode = fwnode_graph_get_endpoint_by_id(dev_fwnode(dev),
+						    UB913_PAD_SINK, 0, 0);
+	if (!ep_fwnode) {
+		dev_err_probe(dev, -ENOENT, "No sink endpoint\n");
+		return -ENOENT;
+	}
+
+	ret = fwnode_property_read_u32(ep_fwnode, "pclk-sample",
+				       &priv->pclk_polarity);
+
+	fwnode_handle_put(ep_fwnode);
+
+	if (ret) {
+		dev_err_probe(dev, ret, "failed to parse 'pclk-sample'\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+static int ub913_hw_init(struct ub913_data *priv)
+{
+	struct device *dev = &priv->client->dev;
+	bool mode_override;
+	u8 mode;
+	int ret;
+	u8 v;
+
+	ret = ub913_read(priv, UB913_REG_MODE_SEL, &v);
+	if (ret)
+		return ret;
+
+	if (!(v & UB913_REG_MODE_SEL_MODE_UP_TO_DATE))
+		return dev_err_probe(dev, -ENODEV,
+				     "Mode value not stabilized\n");
+
+	mode_override = v & UB913_REG_MODE_SEL_MODE_OVERRIDE;
+	mode = v & UB913_REG_MODE_SEL_MODE_MASK;
+
+	dev_dbg(dev, "mode from %s: %#x\n",
+		mode_override ? "reg" : "deserializer", mode);
+
+	ret = ub913_i2c_master_init(priv);
+	if (ret)
+		return dev_err_probe(dev, ret, "i2c master init failed\n");
+
+	ub913_read(priv, UB913_REG_GENERAL_CFG, &v);
+	v &= ~UB913_REG_GENERAL_CFG_PCLK_RISING;
+	v |= priv->pclk_polarity ? UB913_REG_GENERAL_CFG_PCLK_RISING : 0;
+	ub913_write(priv, UB913_REG_GENERAL_CFG, v);
+
+	return 0;
+}
+
+static int ub913_subdev_init(struct ub913_data *priv)
+{
+	struct device *dev = &priv->client->dev;
+	int ret;
+
+	v4l2_i2c_subdev_init(&priv->sd, priv->client, &ub913_subdev_ops);
+	priv->sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE | V4L2_SUBDEV_FL_STREAMS;
+	priv->sd.entity.function = MEDIA_ENT_F_VID_IF_BRIDGE;
+	priv->sd.entity.ops = &ub913_entity_ops;
+
+	priv->pads[0].flags = MEDIA_PAD_FL_SINK;
+	priv->pads[1].flags = MEDIA_PAD_FL_SOURCE;
+
+	ret = media_entity_pads_init(&priv->sd.entity, 2, priv->pads);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to init pads\n");
+
+	priv->sd.fwnode = fwnode_graph_get_endpoint_by_id(dev_fwnode(dev),
+							  UB913_PAD_SOURCE, 0,
+							  0);
+
+	if (!priv->sd.fwnode) {
+		ret = -ENODEV;
+		dev_err_probe(dev, ret, "Missing TX endpoint\n");
+		goto err_entity_cleanup;
+	}
+
+	ret = v4l2_subdev_init_finalize(&priv->sd);
+	if (ret)
+		goto err_fwnode_put;
+
+	ret = ub913_v4l2_notifier_register(priv);
+	if (ret) {
+		dev_err_probe(dev, ret,
+			      "v4l2 subdev notifier register failed\n");
+		goto err_subdev_cleanup;
+	}
+
+	ret = v4l2_async_register_subdev(&priv->sd);
+	if (ret) {
+		dev_err_probe(dev, ret, "v4l2_async_register_subdev error\n");
+		goto err_unreg_notif;
+	}
+
+	return 0;
+
+err_unreg_notif:
+	ub913_v4l2_nf_unregister(priv);
+err_subdev_cleanup:
+	v4l2_subdev_cleanup(&priv->sd);
+err_fwnode_put:
+	fwnode_handle_put(priv->sd.fwnode);
+err_entity_cleanup:
+	media_entity_cleanup(&priv->sd.entity);
+
+	return ret;
+}
+
+static void ub913_subdev_uninit(struct ub913_data *priv)
+{
+	v4l2_async_unregister_subdev(&priv->sd);
+	ub913_v4l2_nf_unregister(priv);
+	v4l2_subdev_cleanup(&priv->sd);
+	fwnode_handle_put(priv->sd.fwnode);
+	media_entity_cleanup(&priv->sd.entity);
+}
+
+static int ub913_probe(struct i2c_client *client)
+{
+	struct device *dev = &client->dev;
+	struct ub913_data *priv;
+	int ret;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->client = client;
+
+	priv->plat_data = dev_get_platdata(&client->dev);
+	if (!priv->plat_data)
+		return dev_err_probe(dev, -ENODEV, "Platform data missing\n");
+
+	priv->regmap = devm_regmap_init_i2c(client, &ub913_regmap_config);
+	if (IS_ERR(priv->regmap))
+		return dev_err_probe(dev, PTR_ERR(priv->regmap),
+				     "Failed to init regmap\n");
+
+	/*
+	 * ub913 can also work without ext clock, but that is not supported by
+	 * the driver yet.
+	 */
+	priv->clkin = devm_clk_get(dev, "clkin");
+	if (IS_ERR(priv->clkin))
+		return dev_err_probe(dev, PTR_ERR(priv->clkin),
+				     "Cannot get CLKIN\n");
+
+	ret = ub913_parse_dt(priv);
+	if (ret)
+		return ret;
+
+	ret = ub913_hw_init(priv);
+	if (ret)
+		return ret;
+
+	ret = ub913_gpiochip_probe(priv);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to init gpiochip\n");
+
+	ret = ub913_register_clkout(priv);
+	if (ret) {
+		dev_err_probe(dev, ret, "Failed to register clkout\n");
+		goto err_gpiochip_remove;
+	}
+
+	ret = ub913_subdev_init(priv);
+	if (ret)
+		goto err_gpiochip_remove;
+
+	ret = ub913_add_i2c_adapter(priv);
+	if (ret) {
+		dev_err_probe(dev, ret, "failed to add remote i2c adapter\n");
+		goto err_subdev_uninit;
+	}
+
+	return 0;
+
+err_subdev_uninit:
+	ub913_subdev_uninit(priv);
+err_gpiochip_remove:
+	ub913_gpiochip_remove(priv);
+
+	return ret;
+}
+
+static void ub913_remove(struct i2c_client *client)
+{
+	struct v4l2_subdev *sd = i2c_get_clientdata(client);
+	struct ub913_data *priv = sd_to_ub913(sd);
+
+	i2c_atr_del_adapter(priv->plat_data->atr, priv->plat_data->port);
+
+	ub913_subdev_uninit(priv);
+
+	ub913_gpiochip_remove(priv);
+}
+
+static const struct i2c_device_id ub913_id[] = { { "ds90ub913a-q1", 0 }, {} };
+MODULE_DEVICE_TABLE(i2c, ub913_id);
+
+static const struct of_device_id ub913_dt_ids[] = {
+	{ .compatible = "ti,ds90ub913a-q1" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, ub913_dt_ids);
+
+static struct i2c_driver ds90ub913_driver = {
+	.probe_new	= ub913_probe,
+	.remove		= ub913_remove,
+	.id_table	= ub913_id,
+	.driver = {
+		.name	= "ds90ub913a",
+		.of_match_table = ub913_dt_ids,
+	},
+};
+module_i2c_driver(ds90ub913_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Texas Instruments DS90UB913 FPD-Link III Serializer Driver");
+MODULE_AUTHOR("Luca Ceresoli <luca@lucaceresoli.net>");
+MODULE_AUTHOR("Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>");
+MODULE_IMPORT_NS(I2C_ATR);
-- 
2.34.1

Hi Tomi,

I get this compiler warning:

media-git/drivers/media/i2c/ds90ub913.c: In function 'ub913_log_status':
media-git/drivers/media/i2c/ds90ub913.c:483:9: warning: 'v' may be used uninitialized [-Wmaybe-uninitialized]
  483 |         ub913_write(priv, UB913_REG_GENERAL_CFG,
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  484 |                     v | UB913_REG_GENERAL_CFG_CRC_ERR_RESET);
      |                     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
media-git/drivers/media/i2c/ds90ub913.c:472:12: note: 'v' was declared here
  472 |         u8 v, v1, v2;
      |            ^

Can you post a patch fixing this?

Thank you!

	Hans

On 19/06/2023 14:22, Tomi Valkeinen wrote:
> Add driver for TI DS90UB913 FPD-Link III Serializer.
> 
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> ---
>  drivers/media/i2c/Kconfig     |  13 +
>  drivers/media/i2c/Makefile    |   1 +
>  drivers/media/i2c/ds90ub913.c | 906 ++++++++++++++++++++++++++++++++++
>  3 files changed, 920 insertions(+)
>  create mode 100644 drivers/media/i2c/ds90ub913.c
> 
> diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
> index 60eafa1f5681..31d46e0bfbcf 100644
> --- a/drivers/media/i2c/Kconfig
> +++ b/drivers/media/i2c/Kconfig
> @@ -1630,6 +1630,19 @@ endmenu
>  
>  menu "Video serializers and deserializers"
>  
> +config VIDEO_DS90UB913
> +	tristate "TI DS90UB913 FPD-Link III Serializer"
> +	depends on OF && I2C && VIDEO_DEV && COMMON_CLK
> +	select I2C_ATR
> +	select MEDIA_CONTROLLER
> +	select GPIOLIB
> +	select REGMAP_I2C
> +	select V4L2_FWNODE
> +	select VIDEO_V4L2_SUBDEV_API
> +	help
> +	  Device driver for the Texas Instruments DS90UB913
> +	  FPD-Link III Serializer.
> +
>  config VIDEO_DS90UB960
>  	tristate "TI FPD-Link III/IV Deserializers"
>  	depends on OF && I2C && VIDEO_DEV && COMMON_CLK
> diff --git a/drivers/media/i2c/Makefile b/drivers/media/i2c/Makefile
> index 0da487e35022..c2507520e01c 100644
> --- a/drivers/media/i2c/Makefile
> +++ b/drivers/media/i2c/Makefile
> @@ -28,6 +28,7 @@ obj-$(CONFIG_VIDEO_CS3308) += cs3308.o
>  obj-$(CONFIG_VIDEO_CS5345) += cs5345.o
>  obj-$(CONFIG_VIDEO_CS53L32A) += cs53l32a.o
>  obj-$(CONFIG_VIDEO_CX25840) += cx25840/
> +obj-$(CONFIG_VIDEO_DS90UB913) += ds90ub913.o
>  obj-$(CONFIG_VIDEO_DS90UB960) += ds90ub960.o
>  obj-$(CONFIG_VIDEO_DW9714) += dw9714.o
>  obj-$(CONFIG_VIDEO_DW9768) += dw9768.o
> diff --git a/drivers/media/i2c/ds90ub913.c b/drivers/media/i2c/ds90ub913.c
> new file mode 100644
> index 000000000000..203f7cceae23
> --- /dev/null
> +++ b/drivers/media/i2c/ds90ub913.c
> @@ -0,0 +1,906 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Driver for the Texas Instruments DS90UB913 video serializer
> + *
> + * Based on a driver from Luca Ceresoli <luca@lucaceresoli.net>
> + *
> + * Copyright (c) 2019 Luca Ceresoli <luca@lucaceresoli.net>
> + * Copyright (c) 2023 Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
> + */
> +
> +#include <linux/clk-provider.h>
> +#include <linux/clk.h>
> +#include <linux/delay.h>
> +#include <linux/fwnode.h>
> +#include <linux/gpio/driver.h>
> +#include <linux/i2c-atr.h>
> +#include <linux/i2c.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/property.h>
> +#include <linux/regmap.h>
> +
> +#include <media/i2c/ds90ub9xx.h>
> +#include <media/v4l2-subdev.h>
> +
> +#define UB913_PAD_SINK			0
> +#define UB913_PAD_SOURCE		1
> +
> +/*
> + * UB913 has 4 gpios, but gpios 3 and 4 are reserved for external oscillator
> + * mode. Thus we only support 2 gpios for now.
> + */
> +#define UB913_NUM_GPIOS			2
> +
> +#define UB913_REG_RESET_CTL			0x01
> +#define UB913_REG_RESET_CTL_DIGITAL_RESET_1	BIT(1)
> +#define UB913_REG_RESET_CTL_DIGITAL_RESET_0	BIT(0)
> +
> +#define UB913_REG_GENERAL_CFG			0x03
> +#define UB913_REG_GENERAL_CFG_CRC_ERR_RESET	BIT(5)
> +#define UB913_REG_GENERAL_CFG_PCLK_RISING	BIT(0)
> +
> +#define UB913_REG_MODE_SEL			0x05
> +#define UB913_REG_MODE_SEL_MODE_OVERRIDE	BIT(5)
> +#define UB913_REG_MODE_SEL_MODE_UP_TO_DATE	BIT(4)
> +#define UB913_REG_MODE_SEL_MODE_MASK		GENMASK(3, 0)
> +
> +#define UB913_REG_CRC_ERRORS_LSB		0x0a
> +#define UB913_REG_CRC_ERRORS_MSB		0x0b
> +
> +#define UB913_REG_GENERAL_STATUS		0x0c
> +
> +#define UB913_REG_GPIO_CFG(n)			(0x0d + (n))
> +#define UB913_REG_GPIO_CFG_ENABLE(n)		BIT(0 + (n) * 4)
> +#define UB913_REG_GPIO_CFG_DIR_INPUT(n)		BIT(1 + (n) * 4)
> +#define UB913_REG_GPIO_CFG_REMOTE_EN(n)		BIT(2 + (n) * 4)
> +#define UB913_REG_GPIO_CFG_OUT_VAL(n)		BIT(3 + (n) * 4)
> +#define UB913_REG_GPIO_CFG_MASK(n)		(0xf << ((n) * 4))
> +
> +#define UB913_REG_SCL_HIGH_TIME			0x11
> +#define UB913_REG_SCL_LOW_TIME			0x12
> +
> +#define UB913_REG_PLL_OVR			0x35
> +
> +struct ub913_data {
> +	struct i2c_client	*client;
> +	struct regmap		*regmap;
> +	struct clk		*clkin;
> +
> +	struct gpio_chip	gpio_chip;
> +
> +	struct v4l2_subdev	sd;
> +	struct media_pad	pads[2];
> +
> +	struct v4l2_async_notifier	notifier;
> +
> +	struct v4l2_subdev	*source_sd;
> +	u16			source_sd_pad;
> +
> +	u64			enabled_source_streams;
> +
> +	struct clk_hw		*clkout_clk_hw;
> +
> +	struct ds90ub9xx_platform_data *plat_data;
> +
> +	u32			pclk_polarity;
> +};
> +
> +static inline struct ub913_data *sd_to_ub913(struct v4l2_subdev *sd)
> +{
> +	return container_of(sd, struct ub913_data, sd);
> +}
> +
> +struct ub913_format_info {
> +	u32 incode;
> +	u32 outcode;
> +};
> +
> +static const struct ub913_format_info ub913_formats[] = {
> +	/* Only RAW10 with 8-bit payload is supported at the moment */
> +	{ .incode = MEDIA_BUS_FMT_YUYV8_2X8, .outcode = MEDIA_BUS_FMT_YUYV8_1X16 },
> +	{ .incode = MEDIA_BUS_FMT_UYVY8_2X8, .outcode = MEDIA_BUS_FMT_UYVY8_1X16 },
> +	{ .incode = MEDIA_BUS_FMT_VYUY8_2X8, .outcode = MEDIA_BUS_FMT_VYUY8_1X16 },
> +	{ .incode = MEDIA_BUS_FMT_YVYU8_2X8, .outcode = MEDIA_BUS_FMT_YVYU8_1X16 },
> +};
> +
> +static const struct ub913_format_info *ub913_find_format(u32 incode)
> +{
> +	unsigned int i;
> +
> +	for (i = 0; i < ARRAY_SIZE(ub913_formats); i++) {
> +		if (ub913_formats[i].incode == incode)
> +			return &ub913_formats[i];
> +	}
> +
> +	return NULL;
> +}
> +
> +static int ub913_read(const struct ub913_data *priv, u8 reg, u8 *val)
> +{
> +	unsigned int v;
> +	int ret;
> +
> +	ret = regmap_read(priv->regmap, reg, &v);
> +	if (ret < 0) {
> +		dev_err(&priv->client->dev,
> +			"Cannot read register 0x%02x: %d!\n", reg, ret);
> +		return ret;
> +	}
> +
> +	*val = v;
> +	return 0;
> +}
> +
> +static int ub913_write(const struct ub913_data *priv, u8 reg, u8 val)
> +{
> +	int ret;
> +
> +	ret = regmap_write(priv->regmap, reg, val);
> +	if (ret < 0)
> +		dev_err(&priv->client->dev,
> +			"Cannot write register 0x%02x: %d!\n", reg, ret);
> +
> +	return ret;
> +}
> +
> +/*
> + * GPIO chip
> + */
> +static int ub913_gpio_get_direction(struct gpio_chip *gc, unsigned int offset)
> +{
> +	return GPIO_LINE_DIRECTION_OUT;
> +}
> +
> +static int ub913_gpio_direction_out(struct gpio_chip *gc, unsigned int offset,
> +				    int value)
> +{
> +	struct ub913_data *priv = gpiochip_get_data(gc);
> +	unsigned int reg_idx = offset / 2;
> +	unsigned int field_idx = offset % 2;
> +
> +	return regmap_update_bits(priv->regmap, UB913_REG_GPIO_CFG(reg_idx),
> +				  UB913_REG_GPIO_CFG_MASK(field_idx),
> +				  UB913_REG_GPIO_CFG_ENABLE(field_idx) |
> +					  (value ? UB913_REG_GPIO_CFG_OUT_VAL(field_idx) :
> +						   0));
> +}
> +
> +static void ub913_gpio_set(struct gpio_chip *gc, unsigned int offset, int value)
> +{
> +	ub913_gpio_direction_out(gc, offset, value);
> +}
> +
> +static int ub913_gpio_of_xlate(struct gpio_chip *gc,
> +			       const struct of_phandle_args *gpiospec,
> +			       u32 *flags)
> +{
> +	if (flags)
> +		*flags = gpiospec->args[1];
> +
> +	return gpiospec->args[0];
> +}
> +
> +static int ub913_gpiochip_probe(struct ub913_data *priv)
> +{
> +	struct device *dev = &priv->client->dev;
> +	struct gpio_chip *gc = &priv->gpio_chip;
> +	int ret;
> +
> +	/* Initialize GPIOs 0 and 1 to local control, tri-state */
> +	ub913_write(priv, UB913_REG_GPIO_CFG(0), 0);
> +
> +	gc->label = dev_name(dev);
> +	gc->parent = dev;
> +	gc->owner = THIS_MODULE;
> +	gc->base = -1;
> +	gc->can_sleep = true;
> +	gc->ngpio = UB913_NUM_GPIOS;
> +	gc->get_direction = ub913_gpio_get_direction;
> +	gc->direction_output = ub913_gpio_direction_out;
> +	gc->set = ub913_gpio_set;
> +	gc->of_xlate = ub913_gpio_of_xlate;
> +	gc->of_gpio_n_cells = 2;
> +
> +	ret = gpiochip_add_data(gc, priv);
> +	if (ret) {
> +		dev_err(dev, "Failed to add GPIOs: %d\n", ret);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static void ub913_gpiochip_remove(struct ub913_data *priv)
> +{
> +	gpiochip_remove(&priv->gpio_chip);
> +}
> +
> +static const struct regmap_config ub913_regmap_config = {
> +	.name = "ds90ub913",
> +	.reg_bits = 8,
> +	.val_bits = 8,
> +	.reg_format_endian = REGMAP_ENDIAN_DEFAULT,
> +	.val_format_endian = REGMAP_ENDIAN_DEFAULT,
> +};
> +
> +/*
> + * V4L2
> + */
> +
> +static int ub913_enable_streams(struct v4l2_subdev *sd,
> +				struct v4l2_subdev_state *state, u32 pad,
> +				u64 streams_mask)
> +{
> +	struct ub913_data *priv = sd_to_ub913(sd);
> +	u64 sink_streams;
> +	int ret;
> +
> +	sink_streams = v4l2_subdev_state_xlate_streams(state, UB913_PAD_SOURCE,
> +						       UB913_PAD_SINK,
> +						       &streams_mask);
> +
> +	ret = v4l2_subdev_enable_streams(priv->source_sd, priv->source_sd_pad,
> +					 sink_streams);
> +	if (ret)
> +		return ret;
> +
> +	priv->enabled_source_streams |= streams_mask;
> +
> +	return 0;
> +}
> +
> +static int ub913_disable_streams(struct v4l2_subdev *sd,
> +				 struct v4l2_subdev_state *state, u32 pad,
> +				 u64 streams_mask)
> +{
> +	struct ub913_data *priv = sd_to_ub913(sd);
> +	u64 sink_streams;
> +	int ret;
> +
> +	sink_streams = v4l2_subdev_state_xlate_streams(state, UB913_PAD_SOURCE,
> +						       UB913_PAD_SINK,
> +						       &streams_mask);
> +
> +	ret = v4l2_subdev_disable_streams(priv->source_sd, priv->source_sd_pad,
> +					  sink_streams);
> +	if (ret)
> +		return ret;
> +
> +	priv->enabled_source_streams &= ~streams_mask;
> +
> +	return 0;
> +}
> +
> +static int _ub913_set_routing(struct v4l2_subdev *sd,
> +			      struct v4l2_subdev_state *state,
> +			      struct v4l2_subdev_krouting *routing)
> +{
> +	static const struct v4l2_mbus_framefmt in_format = {
> +		.width = 640,
> +		.height = 480,
> +		.code = MEDIA_BUS_FMT_UYVY8_2X8,
> +		.field = V4L2_FIELD_NONE,
> +		.colorspace = V4L2_COLORSPACE_SRGB,
> +		.ycbcr_enc = V4L2_YCBCR_ENC_601,
> +		.quantization = V4L2_QUANTIZATION_LIM_RANGE,
> +		.xfer_func = V4L2_XFER_FUNC_SRGB,
> +	};
> +	static const struct v4l2_mbus_framefmt out_format = {
> +		.width = 640,
> +		.height = 480,
> +		.code = MEDIA_BUS_FMT_UYVY8_1X16,
> +		.field = V4L2_FIELD_NONE,
> +		.colorspace = V4L2_COLORSPACE_SRGB,
> +		.ycbcr_enc = V4L2_YCBCR_ENC_601,
> +		.quantization = V4L2_QUANTIZATION_LIM_RANGE,
> +		.xfer_func = V4L2_XFER_FUNC_SRGB,
> +	};
> +	struct v4l2_subdev_stream_configs *stream_configs;
> +	unsigned int i;
> +	int ret;
> +
> +	/*
> +	 * Note: we can only support up to V4L2_FRAME_DESC_ENTRY_MAX, until
> +	 * frame desc is made dynamically allocated.
> +	 */
> +
> +	if (routing->num_routes > V4L2_FRAME_DESC_ENTRY_MAX)
> +		return -EINVAL;
> +
> +	ret = v4l2_subdev_routing_validate(sd, routing,
> +					   V4L2_SUBDEV_ROUTING_ONLY_1_TO_1);
> +	if (ret)
> +		return ret;
> +
> +	ret = v4l2_subdev_set_routing(sd, state, routing);
> +	if (ret)
> +		return ret;
> +
> +	stream_configs = &state->stream_configs;
> +
> +	for (i = 0; i < stream_configs->num_configs; i++) {
> +		if (stream_configs->configs[i].pad == UB913_PAD_SINK)
> +			stream_configs->configs[i].fmt = in_format;
> +		else
> +			stream_configs->configs[i].fmt = out_format;
> +	}
> +
> +	return 0;
> +}
> +
> +static int ub913_set_routing(struct v4l2_subdev *sd,
> +			     struct v4l2_subdev_state *state,
> +			     enum v4l2_subdev_format_whence which,
> +			     struct v4l2_subdev_krouting *routing)
> +{
> +	struct ub913_data *priv = sd_to_ub913(sd);
> +
> +	if (which == V4L2_SUBDEV_FORMAT_ACTIVE && priv->enabled_source_streams)
> +		return -EBUSY;
> +
> +	return _ub913_set_routing(sd, state, routing);
> +}
> +
> +static int ub913_get_frame_desc(struct v4l2_subdev *sd, unsigned int pad,
> +				struct v4l2_mbus_frame_desc *fd)
> +{
> +	struct ub913_data *priv = sd_to_ub913(sd);
> +	const struct v4l2_subdev_krouting *routing;
> +	struct v4l2_mbus_frame_desc source_fd;
> +	struct v4l2_subdev_route *route;
> +	struct v4l2_subdev_state *state;
> +	int ret;
> +
> +	if (pad != UB913_PAD_SOURCE)
> +		return -EINVAL;
> +
> +	ret = v4l2_subdev_call(priv->source_sd, pad, get_frame_desc,
> +			       priv->source_sd_pad, &source_fd);
> +	if (ret)
> +		return ret;
> +
> +	memset(fd, 0, sizeof(*fd));
> +
> +	fd->type = V4L2_MBUS_FRAME_DESC_TYPE_PARALLEL;
> +
> +	state = v4l2_subdev_lock_and_get_active_state(sd);
> +
> +	routing = &state->routing;
> +
> +	for_each_active_route(routing, route) {
> +		unsigned int i;
> +
> +		if (route->source_pad != pad)
> +			continue;
> +
> +		for (i = 0; i < source_fd.num_entries; i++) {
> +			if (source_fd.entry[i].stream == route->sink_stream)
> +				break;
> +		}
> +
> +		if (i == source_fd.num_entries) {
> +			dev_err(&priv->client->dev,
> +				"Failed to find stream from source frame desc\n");
> +			ret = -EPIPE;
> +			goto out_unlock;
> +		}
> +
> +		fd->entry[fd->num_entries].stream = route->source_stream;
> +		fd->entry[fd->num_entries].flags = source_fd.entry[i].flags;
> +		fd->entry[fd->num_entries].length = source_fd.entry[i].length;
> +		fd->entry[fd->num_entries].pixelcode =
> +			source_fd.entry[i].pixelcode;
> +
> +		fd->num_entries++;
> +	}
> +
> +out_unlock:
> +	v4l2_subdev_unlock_state(state);
> +
> +	return ret;
> +}
> +
> +static int ub913_set_fmt(struct v4l2_subdev *sd,
> +			 struct v4l2_subdev_state *state,
> +			 struct v4l2_subdev_format *format)
> +{
> +	struct ub913_data *priv = sd_to_ub913(sd);
> +	struct v4l2_mbus_framefmt *fmt;
> +	const struct ub913_format_info *finfo;
> +
> +	if (format->which == V4L2_SUBDEV_FORMAT_ACTIVE &&
> +	    priv->enabled_source_streams)
> +		return -EBUSY;
> +
> +	/* Source format is fully defined by the sink format, so not settable */
> +	if (format->pad == UB913_PAD_SOURCE)
> +		return v4l2_subdev_get_fmt(sd, state, format);
> +
> +	finfo = ub913_find_format(format->format.code);
> +	if (!finfo) {
> +		finfo = &ub913_formats[0];
> +		format->format.code = finfo->incode;
> +	}
> +
> +	/* Set sink format */
> +	fmt = v4l2_subdev_state_get_stream_format(state, format->pad,
> +						  format->stream);
> +	if (!fmt)
> +		return -EINVAL;
> +
> +	*fmt = format->format;
> +
> +	/* Propagate to source format, and adjust the mbus code */
> +	fmt = v4l2_subdev_state_get_opposite_stream_format(state, format->pad,
> +							   format->stream);
> +	if (!fmt)
> +		return -EINVAL;
> +
> +	format->format.code = finfo->outcode;
> +
> +	*fmt = format->format;
> +
> +	return 0;
> +}
> +
> +static int ub913_init_cfg(struct v4l2_subdev *sd,
> +			  struct v4l2_subdev_state *state)
> +{
> +	struct v4l2_subdev_route routes[] = {
> +		{
> +			.sink_pad = UB913_PAD_SINK,
> +			.sink_stream = 0,
> +			.source_pad = UB913_PAD_SOURCE,
> +			.source_stream = 0,
> +			.flags = V4L2_SUBDEV_ROUTE_FL_ACTIVE,
> +		},
> +	};
> +
> +	struct v4l2_subdev_krouting routing = {
> +		.num_routes = ARRAY_SIZE(routes),
> +		.routes = routes,
> +	};
> +
> +	return _ub913_set_routing(sd, state, &routing);
> +}
> +
> +static int ub913_log_status(struct v4l2_subdev *sd)
> +{
> +	struct ub913_data *priv = sd_to_ub913(sd);
> +	struct device *dev = &priv->client->dev;
> +	u8 v, v1, v2;
> +
> +	ub913_read(priv, UB913_REG_MODE_SEL, &v);
> +	dev_info(dev, "MODE_SEL %#02x\n", v);
> +
> +	ub913_read(priv, UB913_REG_CRC_ERRORS_LSB, &v1);
> +	ub913_read(priv, UB913_REG_CRC_ERRORS_MSB, &v2);
> +	dev_info(dev, "CRC errors %u\n", v1 | (v2 << 8));
> +
> +	/* clear CRC errors */
> +	ub913_read(priv, UB913_REG_GENERAL_CFG, &v);
> +	ub913_write(priv, UB913_REG_GENERAL_CFG,
> +		    v | UB913_REG_GENERAL_CFG_CRC_ERR_RESET);
> +	ub913_write(priv, UB913_REG_GENERAL_CFG, v);
> +
> +	ub913_read(priv, UB913_REG_GENERAL_STATUS, &v);
> +	dev_info(dev, "GENERAL_STATUS %#02x\n", v);
> +
> +	ub913_read(priv, UB913_REG_PLL_OVR, &v);
> +	dev_info(dev, "PLL_OVR %#02x\n", v);
> +
> +	return 0;
> +}
> +
> +static const struct v4l2_subdev_core_ops ub913_subdev_core_ops = {
> +	.log_status = ub913_log_status,
> +};
> +
> +static const struct v4l2_subdev_pad_ops ub913_pad_ops = {
> +	.enable_streams = ub913_enable_streams,
> +	.disable_streams = ub913_disable_streams,
> +	.set_routing = ub913_set_routing,
> +	.get_frame_desc = ub913_get_frame_desc,
> +	.get_fmt = v4l2_subdev_get_fmt,
> +	.set_fmt = ub913_set_fmt,
> +	.init_cfg = ub913_init_cfg,
> +};
> +
> +static const struct v4l2_subdev_ops ub913_subdev_ops = {
> +	.core = &ub913_subdev_core_ops,
> +	.pad = &ub913_pad_ops,
> +};
> +
> +static const struct media_entity_operations ub913_entity_ops = {
> +	.link_validate = v4l2_subdev_link_validate,
> +};
> +
> +static int ub913_notify_bound(struct v4l2_async_notifier *notifier,
> +			      struct v4l2_subdev *source_subdev,
> +			      struct v4l2_async_subdev *asd)
> +{
> +	struct ub913_data *priv = sd_to_ub913(notifier->sd);
> +	struct device *dev = &priv->client->dev;
> +	int ret;
> +
> +	ret = media_entity_get_fwnode_pad(&source_subdev->entity,
> +					  source_subdev->fwnode,
> +					  MEDIA_PAD_FL_SOURCE);
> +	if (ret < 0) {
> +		dev_err(dev, "Failed to find pad for %s\n",
> +			source_subdev->name);
> +		return ret;
> +	}
> +
> +	priv->source_sd = source_subdev;
> +	priv->source_sd_pad = ret;
> +
> +	ret = media_create_pad_link(&source_subdev->entity, priv->source_sd_pad,
> +				    &priv->sd.entity, UB913_PAD_SINK,
> +				    MEDIA_LNK_FL_ENABLED |
> +					    MEDIA_LNK_FL_IMMUTABLE);
> +	if (ret) {
> +		dev_err(dev, "Unable to link %s:%u -> %s:0\n",
> +			source_subdev->name, priv->source_sd_pad,
> +			priv->sd.name);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static const struct v4l2_async_notifier_operations ub913_notify_ops = {
> +	.bound = ub913_notify_bound,
> +};
> +
> +static int ub913_v4l2_notifier_register(struct ub913_data *priv)
> +{
> +	struct device *dev = &priv->client->dev;
> +	struct v4l2_async_subdev *asd;
> +	struct fwnode_handle *ep_fwnode;
> +	int ret;
> +
> +	ep_fwnode = fwnode_graph_get_endpoint_by_id(dev_fwnode(dev),
> +						    UB913_PAD_SINK, 0, 0);
> +	if (!ep_fwnode) {
> +		dev_err(dev, "No graph endpoint\n");
> +		return -ENODEV;
> +	}
> +
> +	v4l2_async_nf_init(&priv->notifier);
> +
> +	asd = v4l2_async_nf_add_fwnode_remote(&priv->notifier, ep_fwnode,
> +					      struct v4l2_async_subdev);
> +
> +	fwnode_handle_put(ep_fwnode);
> +
> +	if (IS_ERR(asd)) {
> +		dev_err(dev, "Failed to add subdev: %ld", PTR_ERR(asd));
> +		v4l2_async_nf_cleanup(&priv->notifier);
> +		return PTR_ERR(asd);
> +	}
> +
> +	priv->notifier.ops = &ub913_notify_ops;
> +
> +	ret = v4l2_async_subdev_nf_register(&priv->sd, &priv->notifier);
> +	if (ret) {
> +		dev_err(dev, "Failed to register subdev_notifier");
> +		v4l2_async_nf_cleanup(&priv->notifier);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static void ub913_v4l2_nf_unregister(struct ub913_data *priv)
> +{
> +	v4l2_async_nf_unregister(&priv->notifier);
> +	v4l2_async_nf_cleanup(&priv->notifier);
> +}
> +
> +static int ub913_register_clkout(struct ub913_data *priv)
> +{
> +	struct device *dev = &priv->client->dev;
> +	const char *name;
> +	int ret;
> +
> +	name = kasprintf(GFP_KERNEL, "ds90ub913.%s.clk_out", dev_name(dev));
> +	if (!name)
> +		return -ENOMEM;
> +
> +	priv->clkout_clk_hw = devm_clk_hw_register_fixed_factor(dev, name,
> +		__clk_get_name(priv->clkin), 0, 1, 2);
> +
> +	kfree(name);
> +
> +	if (IS_ERR(priv->clkout_clk_hw))
> +		return dev_err_probe(dev, PTR_ERR(priv->clkout_clk_hw),
> +				     "Cannot register clkout hw\n");
> +
> +	ret = devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get,
> +					  priv->clkout_clk_hw);
> +	if (ret)
> +		return dev_err_probe(dev, ret,
> +				     "Cannot add OF clock provider\n");
> +
> +	return 0;
> +}
> +
> +static int ub913_i2c_master_init(struct ub913_data *priv)
> +{
> +	/* i2c fast mode */
> +	u32 scl_high = 600 + 300; /* high period + rise time, ns */
> +	u32 scl_low = 1300 + 300; /* low period + fall time, ns */
> +	unsigned long ref;
> +	int ret;
> +
> +	ref = clk_get_rate(priv->clkin) / 2;
> +
> +	scl_high = div64_u64((u64)scl_high * ref, 1000000000);
> +	scl_low = div64_u64((u64)scl_low * ref, 1000000000);
> +
> +	ret = ub913_write(priv, UB913_REG_SCL_HIGH_TIME, scl_high);
> +	if (ret)
> +		return ret;
> +
> +	ret = ub913_write(priv, UB913_REG_SCL_LOW_TIME, scl_low);
> +	if (ret)
> +		return ret;
> +
> +	return 0;
> +}
> +
> +static int ub913_add_i2c_adapter(struct ub913_data *priv)
> +{
> +	struct device *dev = &priv->client->dev;
> +	struct fwnode_handle *i2c_handle;
> +	int ret;
> +
> +	i2c_handle = device_get_named_child_node(dev, "i2c");
> +	if (!i2c_handle)
> +		return 0;
> +
> +	ret = i2c_atr_add_adapter(priv->plat_data->atr, priv->plat_data->port,
> +				  dev, i2c_handle);
> +
> +	fwnode_handle_put(i2c_handle);
> +
> +	if (ret)
> +		return ret;
> +
> +	return 0;
> +}
> +
> +static int ub913_parse_dt(struct ub913_data *priv)
> +{
> +	struct device *dev = &priv->client->dev;
> +	struct fwnode_handle *ep_fwnode;
> +	int ret;
> +
> +	ep_fwnode = fwnode_graph_get_endpoint_by_id(dev_fwnode(dev),
> +						    UB913_PAD_SINK, 0, 0);
> +	if (!ep_fwnode) {
> +		dev_err_probe(dev, -ENOENT, "No sink endpoint\n");
> +		return -ENOENT;
> +	}
> +
> +	ret = fwnode_property_read_u32(ep_fwnode, "pclk-sample",
> +				       &priv->pclk_polarity);
> +
> +	fwnode_handle_put(ep_fwnode);
> +
> +	if (ret) {
> +		dev_err_probe(dev, ret, "failed to parse 'pclk-sample'\n");
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static int ub913_hw_init(struct ub913_data *priv)
> +{
> +	struct device *dev = &priv->client->dev;
> +	bool mode_override;
> +	u8 mode;
> +	int ret;
> +	u8 v;
> +
> +	ret = ub913_read(priv, UB913_REG_MODE_SEL, &v);
> +	if (ret)
> +		return ret;
> +
> +	if (!(v & UB913_REG_MODE_SEL_MODE_UP_TO_DATE))
> +		return dev_err_probe(dev, -ENODEV,
> +				     "Mode value not stabilized\n");
> +
> +	mode_override = v & UB913_REG_MODE_SEL_MODE_OVERRIDE;
> +	mode = v & UB913_REG_MODE_SEL_MODE_MASK;
> +
> +	dev_dbg(dev, "mode from %s: %#x\n",
> +		mode_override ? "reg" : "deserializer", mode);
> +
> +	ret = ub913_i2c_master_init(priv);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "i2c master init failed\n");
> +
> +	ub913_read(priv, UB913_REG_GENERAL_CFG, &v);
> +	v &= ~UB913_REG_GENERAL_CFG_PCLK_RISING;
> +	v |= priv->pclk_polarity ? UB913_REG_GENERAL_CFG_PCLK_RISING : 0;
> +	ub913_write(priv, UB913_REG_GENERAL_CFG, v);
> +
> +	return 0;
> +}
> +
> +static int ub913_subdev_init(struct ub913_data *priv)
> +{
> +	struct device *dev = &priv->client->dev;
> +	int ret;
> +
> +	v4l2_i2c_subdev_init(&priv->sd, priv->client, &ub913_subdev_ops);
> +	priv->sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE | V4L2_SUBDEV_FL_STREAMS;
> +	priv->sd.entity.function = MEDIA_ENT_F_VID_IF_BRIDGE;
> +	priv->sd.entity.ops = &ub913_entity_ops;
> +
> +	priv->pads[0].flags = MEDIA_PAD_FL_SINK;
> +	priv->pads[1].flags = MEDIA_PAD_FL_SOURCE;
> +
> +	ret = media_entity_pads_init(&priv->sd.entity, 2, priv->pads);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "Failed to init pads\n");
> +
> +	priv->sd.fwnode = fwnode_graph_get_endpoint_by_id(dev_fwnode(dev),
> +							  UB913_PAD_SOURCE, 0,
> +							  0);
> +
> +	if (!priv->sd.fwnode) {
> +		ret = -ENODEV;
> +		dev_err_probe(dev, ret, "Missing TX endpoint\n");
> +		goto err_entity_cleanup;
> +	}
> +
> +	ret = v4l2_subdev_init_finalize(&priv->sd);
> +	if (ret)
> +		goto err_fwnode_put;
> +
> +	ret = ub913_v4l2_notifier_register(priv);
> +	if (ret) {
> +		dev_err_probe(dev, ret,
> +			      "v4l2 subdev notifier register failed\n");
> +		goto err_subdev_cleanup;
> +	}
> +
> +	ret = v4l2_async_register_subdev(&priv->sd);
> +	if (ret) {
> +		dev_err_probe(dev, ret, "v4l2_async_register_subdev error\n");
> +		goto err_unreg_notif;
> +	}
> +
> +	return 0;
> +
> +err_unreg_notif:
> +	ub913_v4l2_nf_unregister(priv);
> +err_subdev_cleanup:
> +	v4l2_subdev_cleanup(&priv->sd);
> +err_fwnode_put:
> +	fwnode_handle_put(priv->sd.fwnode);
> +err_entity_cleanup:
> +	media_entity_cleanup(&priv->sd.entity);
> +
> +	return ret;
> +}
> +
> +static void ub913_subdev_uninit(struct ub913_data *priv)
> +{
> +	v4l2_async_unregister_subdev(&priv->sd);
> +	ub913_v4l2_nf_unregister(priv);
> +	v4l2_subdev_cleanup(&priv->sd);
> +	fwnode_handle_put(priv->sd.fwnode);
> +	media_entity_cleanup(&priv->sd.entity);
> +}
> +
> +static int ub913_probe(struct i2c_client *client)
> +{
> +	struct device *dev = &client->dev;
> +	struct ub913_data *priv;
> +	int ret;
> +
> +	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	priv->client = client;
> +
> +	priv->plat_data = dev_get_platdata(&client->dev);
> +	if (!priv->plat_data)
> +		return dev_err_probe(dev, -ENODEV, "Platform data missing\n");
> +
> +	priv->regmap = devm_regmap_init_i2c(client, &ub913_regmap_config);
> +	if (IS_ERR(priv->regmap))
> +		return dev_err_probe(dev, PTR_ERR(priv->regmap),
> +				     "Failed to init regmap\n");
> +
> +	/*
> +	 * ub913 can also work without ext clock, but that is not supported by
> +	 * the driver yet.
> +	 */
> +	priv->clkin = devm_clk_get(dev, "clkin");
> +	if (IS_ERR(priv->clkin))
> +		return dev_err_probe(dev, PTR_ERR(priv->clkin),
> +				     "Cannot get CLKIN\n");
> +
> +	ret = ub913_parse_dt(priv);
> +	if (ret)
> +		return ret;
> +
> +	ret = ub913_hw_init(priv);
> +	if (ret)
> +		return ret;
> +
> +	ret = ub913_gpiochip_probe(priv);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "Failed to init gpiochip\n");
> +
> +	ret = ub913_register_clkout(priv);
> +	if (ret) {
> +		dev_err_probe(dev, ret, "Failed to register clkout\n");
> +		goto err_gpiochip_remove;
> +	}
> +
> +	ret = ub913_subdev_init(priv);
> +	if (ret)
> +		goto err_gpiochip_remove;
> +
> +	ret = ub913_add_i2c_adapter(priv);
> +	if (ret) {
> +		dev_err_probe(dev, ret, "failed to add remote i2c adapter\n");
> +		goto err_subdev_uninit;
> +	}
> +
> +	return 0;
> +
> +err_subdev_uninit:
> +	ub913_subdev_uninit(priv);
> +err_gpiochip_remove:
> +	ub913_gpiochip_remove(priv);
> +
> +	return ret;
> +}
> +
> +static void ub913_remove(struct i2c_client *client)
> +{
> +	struct v4l2_subdev *sd = i2c_get_clientdata(client);
> +	struct ub913_data *priv = sd_to_ub913(sd);
> +
> +	i2c_atr_del_adapter(priv->plat_data->atr, priv->plat_data->port);
> +
> +	ub913_subdev_uninit(priv);
> +
> +	ub913_gpiochip_remove(priv);
> +}
> +
> +static const struct i2c_device_id ub913_id[] = { { "ds90ub913a-q1", 0 }, {} };
> +MODULE_DEVICE_TABLE(i2c, ub913_id);
> +
> +static const struct of_device_id ub913_dt_ids[] = {
> +	{ .compatible = "ti,ds90ub913a-q1" },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, ub913_dt_ids);
> +
> +static struct i2c_driver ds90ub913_driver = {
> +	.probe_new	= ub913_probe,
> +	.remove		= ub913_remove,
> +	.id_table	= ub913_id,
> +	.driver = {
> +		.name	= "ds90ub913a",
> +		.of_match_table = ub913_dt_ids,
> +	},
> +};
> +module_i2c_driver(ds90ub913_driver);
> +
> +MODULE_LICENSE("GPL");
> +MODULE_DESCRIPTION("Texas Instruments DS90UB913 FPD-Link III Serializer Driver");
> +MODULE_AUTHOR("Luca Ceresoli <luca@lucaceresoli.net>");
> +MODULE_AUTHOR("Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>");
> +MODULE_IMPORT_NS(I2C_ATR);