[PATCH 0/2] media: i2c: Add support for RDACM21 camera module

[PATCH 0/2] media: i2c: Add support for RDACM21 camera module

[Jacopo Mondi]

Hello,
   this series introduces support for the RDACM21 camera module, an automotive
camera module based on GMSL technology.

The camera module integrates a MAX9271 serializer, and OV10640 image sensor
coupled with an OV490 ISP. The image sensor and the ISP are programmed loading
the content of an EEPROM chip integrated in the camera module package and
are configured to produce images in 1280x1080 YUYV8 format.

The camera module driver uses the max9271 library to control the serializer,
as the RDACM20 does, to maximize code reuse.

And that's for patch 2/2: it's all unicorns and rainbows!

Patch 1/2 is the less nice one, and is sent as RFC to trigger discussions.

The camera module is connected to a MAXIM development board which integrates a
MAX9286 deserializer. The same expansion board is used with the RDACM20 camera
module and the max9286 driver is meant to work with both cameras without
modifications.

Unfortunately, each camera module has its own characteristics, in details:

- the RDACM20 module integrates a micro-controller unit that pre-programs the
  embedded max9271 serializer at power-up time. The serializer then operates
  with the GMSL reverse channel towards the de-serializer with electrical
  noise immunity feature enabled ("high-threshold" as per chip manual), and
  requires the de-serializer to communicate with the camera module with the
  reverse channel amplitude compensated to 170mV.

- the RDACM21 module is not pre-programmed by any micro-controller, and requires
  the de-serializer to initially maintain the reverse channel amplitude to
  100mV, then after the remote ends have been probed and have enabled the noise
  immunity feature on their reverse channels to increase the amplitude to 170mV
  to guarantee stability of the communications.

For that reason, a mechanism to control the reverse channel amplitude of the
GMSL channel is required. The channel amplitude is controlled by the
de-serializer, but depends on the properties of the remote serializer.

We have explored a few solutions in the past:
1) A dt property that specifies the initial reverse channel amplitude (or simply
   a boolean property that specifies if any channel pre-compensation is
   required). Issue is that the property should be set in the de-serializer
   but depends on the remote side configuration and on which camera module
   is currently connected.

2) Use get_mbus_config to retrieve the GMSL channel configuration. Hyun has
   added to get_mbus_config support for GMSL parameters to control the signal
   polarities[1]. This seems nice, but the channel amplitude has to be set
   -before- the remote end is probed and no subdev operation can be called
   until the remote sub-device have registered.

In this initial version, [1/2] simply adjust the reverse channel after all
remotes have probed, allowing support for RDACM21 but breaking compatibility
with RDACM20.

Any comment on how this should better be handled ?

Thanks
  j

[1] https://github.com/xlnx-hyunkwon/linux-xlnx/commits/hyunk/vision-wip-5.4-next

Jacopo Mondi (2):
  RFC: media: i2c: max9286: Compensate reverse channel
  media: i2c: Add driver for RDACM21 camera module

 MAINTAINERS                 |  12 +
 drivers/media/i2c/Kconfig   |  13 +
 drivers/media/i2c/Makefile  |   2 +
 drivers/media/i2c/max9286.c |   8 +-
 drivers/media/i2c/rdacm21.c | 541 ++++++++++++++++++++++++++++++++++++
 5 files changed, 574 insertions(+), 2 deletions(-)
 create mode 100644 drivers/media/i2c/rdacm21.c

--
2.28.0

[PATCH 1/2] RFC: media: i2c: max9286: Compensate reverse channel

[Jacopo Mondi]

Adjust the MAX9286 reverse channel amplitude to support devices which
are not pre-programmed, like the RDACM21 camera module.

The de-serializer starts with a 100mV channel amplitude, and increases
it to 170mV after all remote ends have probed and enabled their
'high-threshold' noise immunity feature.

Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
---
 drivers/media/i2c/max9286.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/media/i2c/max9286.c b/drivers/media/i2c/max9286.c
index 6852448284ea..992eb15a59be 100644
--- a/drivers/media/i2c/max9286.c
+++ b/drivers/media/i2c/max9286.c
@@ -535,6 +535,11 @@ static int max9286_notify_bound(struct v4l2_async_notifier *notifier,
 	 * - Disable auto-ack as communication on the control channel are now
 	 *   stable.
 	 */
+	max9286_write(priv, 0x3f, MAX9286_EN_REV_CFG | MAX9286_REV_FLEN(35));
+	max9286_write(priv, 0x3b, MAX9286_REV_TRF(1) | MAX9286_REV_AMP(70) |
+		      MAX9286_REV_AMP_X);
+	usleep_range(2000, 2500);
+
 	max9286_check_config_link(priv, priv->source_mask);

 	/*
@@ -953,8 +958,7 @@ static int max9286_setup(struct max9286_priv *priv)
 	 *   high threshold enabled by the serializer driver.
 	 */
 	max9286_write(priv, 0x3f, MAX9286_EN_REV_CFG | MAX9286_REV_FLEN(35));
-	max9286_write(priv, 0x3b, MAX9286_REV_TRF(1) | MAX9286_REV_AMP(70) |
-		      MAX9286_REV_AMP_X);
+	max9286_write(priv, 0x3b, MAX9286_REV_TRF(1) | MAX9286_REV_AMP(100));
 	usleep_range(2000, 2500);

 	/*
--
2.28.0

[PATCH 2/2] media: i2c: Add driver for RDACM21 camera module

[Jacopo Mondi]

The RDACM21 is a GMSL camera supporting 1280x1080 resolution images,
developed by IMI based on an Omnivision OV10640 sensor, an Omnivision
OV490 ISP and a Maxim MAX9271 GMSL serializer.

The driver uses the max9271 library module, to maximize code reuse with
other camera module drivers using the same serializer, such as rdacm20.

Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
---
 MAINTAINERS                 |  12 +
 drivers/media/i2c/Kconfig   |  13 +
 drivers/media/i2c/Makefile  |   2 +
 drivers/media/i2c/rdacm21.c | 541 ++++++++++++++++++++++++++++++++++++
 4 files changed, 568 insertions(+)
 create mode 100644 drivers/media/i2c/rdacm21.c

diff --git a/MAINTAINERS b/MAINTAINERS
index d3126fc2cca2..2349ff8b1bdb 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -14591,6 +14591,18 @@ F:	drivers/media/i2c/max9271.c
 F:	drivers/media/i2c/max9271.h
 F:	drivers/media/i2c/rdacm20.c
 
+RDACM21 Camera Sensor
+M:	Jacopo Mondi <jacopo+renesas@jmondi.org>
+M:	Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
+M:	Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
+M:	Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
+L:	linux-media@vger.kernel.org
+S:	Maintained
+F:	Documentation/devicetree/bindings/media/i2c/rdacm2x-gmsl.yaml
+F:	drivers/media/i2c/max9271.c
+F:	drivers/media/i2c/max9271.h
+F:	drivers/media/i2c/rdacm21.c
+
 RDC R-321X SoC
 M:	Florian Fainelli <florian@openwrt.org>
 S:	Maintained
diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
index 878f66ef2719..cfb3f0bcc4fc 100644
--- a/drivers/media/i2c/Kconfig
+++ b/drivers/media/i2c/Kconfig
@@ -1184,6 +1184,19 @@ config VIDEO_RDACM20
 	  This camera should be used in conjunction with a GMSL
 	  deserialiser such as the MAX9286.
 
+config VIDEO_RDACM21
+	tristate "IMI RDACM21 camera support"
+	depends on I2C
+	select V4L2_FWNODE
+	select VIDEO_V4L2_SUBDEV_API
+	select MEDIA_CONTROLLER
+	help
+	  This driver supports the IMI RDACM21 GMSL camera, used in
+	  ADAS systems.
+
+	  This camera should be used in conjunction with a GMSL
+	  deserialiser such as the MAX9286.
+
 config VIDEO_RJ54N1
 	tristate "Sharp RJ54N1CB0C sensor support"
 	depends on I2C && VIDEO_V4L2
diff --git a/drivers/media/i2c/Makefile b/drivers/media/i2c/Makefile
index f0a77473979d..f3641b58929d 100644
--- a/drivers/media/i2c/Makefile
+++ b/drivers/media/i2c/Makefile
@@ -122,6 +122,8 @@ obj-$(CONFIG_VIDEO_IMX355)	+= imx355.o
 obj-$(CONFIG_VIDEO_MAX9286)	+= max9286.o
 rdacm20-camera_module-objs	:= rdacm20.o max9271.o
 obj-$(CONFIG_VIDEO_RDACM20)	+= rdacm20-camera_module.o
+rdacm21-camera_module-objs	:= rdacm21.o max9271.o
+obj-$(CONFIG_VIDEO_RDACM21)	+= rdacm21-camera_module.o
 obj-$(CONFIG_VIDEO_ST_MIPID02) += st-mipid02.o
 
 obj-$(CONFIG_SDR_MAX2175) += max2175.o
diff --git a/drivers/media/i2c/rdacm21.c b/drivers/media/i2c/rdacm21.c
new file mode 100644
index 000000000000..9cb57b0058c7
--- /dev/null
+++ b/drivers/media/i2c/rdacm21.c
@@ -0,0 +1,541 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * IMI RDACM21 GMSL Camera Driver
+ *
+ * Copyright (C) 2017-2020 Jacopo Mondi
+ * Copyright (C) 2017-2019 Kieran Bingham
+ * Copyright (C) 2017-2019 Laurent Pinchart
+ * Copyright (C) 2017-2019 Niklas Söderlund
+ * Copyright (C) 2016 Renesas Electronics Corporation
+ * Copyright (C) 2015 Cogent Embedded, Inc.
+ */
+
+#include <linux/delay.h>
+#include <linux/fwnode.h>
+#include <linux/init.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/videodev2.h>
+
+#include <media/v4l2-async.h>
+#include <media/v4l2-ctrls.h>
+#include <media/v4l2-subdev.h>
+#include "max9271.h"
+
+#define OV10640_I2C_ADDRESS		0x30
+#define OV10640_ID_LOW			0xa6
+
+#define OV490_I2C_ADDRESS		0x24
+
+#define OV490_ISP_HSIZE_LOW		0x60
+#define OV490_ISP_HSIZE_HIGH		0x61
+#define OV490_ISP_VSIZE_LOW		0x62
+#define OV490_ISP_VSIZE_HIGH		0x63
+
+#define OV490_PID			0x300a
+#define OV490_VER			0x300b
+#define OV490_ID_VAL			0x0490
+#define OV490_ID(_p, _v)		((((_p) & 0xff) << 8) | ((_v) & 0xff))
+
+/*
+ * As the driver supports a single format and resolution we can hardcode
+ * the pixel rate. The OV490 pixel clock is set to 100MHz, set the pixel rate
+ * to 50Mhz (2 samples per pixels).
+ */
+#define OV10640_PIXEL_RATE		(50000000)
+
+struct rdacm21_device {
+	struct device			*dev;
+	struct max9271_device		*serializer;
+	struct i2c_client		*isp;
+	struct v4l2_subdev		sd;
+	struct media_pad		pad;
+	struct v4l2_mbus_framefmt	fmt;
+	struct v4l2_ctrl_handler	ctrls;
+	u32				addrs[32];
+	bool				high_threshold;
+};
+
+static inline struct rdacm21_device *sd_to_rdacm21(struct v4l2_subdev *sd)
+{
+	return container_of(sd, struct rdacm21_device, sd);
+}
+
+static inline struct rdacm21_device *i2c_to_rdacm21(struct i2c_client *client)
+{
+	return sd_to_rdacm21(i2c_get_clientdata(client));
+}
+
+static const struct ov490_reg {
+	u16 reg;
+	u8 val;
+} ov490_regs_wizard[] = {
+	{0xfffd, 0x80},
+	{0xfffe, 0x82},
+	{0x0071, 0x11},
+	{0x0075, 0x11},
+	{0xfffe, 0x29},
+	{0x6010, 0x01},
+	/*
+	 * OV490 EMB line disable in YUV and RAW data,
+	 * NOTE: EMB line is still used in ISP and sensor
+	 */
+	{0xe000, 0x14},
+	{0xfffe, 0x28},
+	{0x6000, 0x04},
+	{0x6004, 0x00},
+	/*
+	 * PCLK polarity - useless due to silicon bug.
+	 * Use 0x808000bb register instead.
+	 */
+	{0x6008, 0x00},
+	{0xfffe, 0x80},
+	{0x0091, 0x00},
+	/* bit[3]=0 - PCLK polarity workaround. */
+	{0x00bb, 0x1d},
+	/* Ov490 FSIN: app_fsin_from_fsync */
+	{0xfffe, 0x85},
+	{0x0008, 0x00},
+	{0x0009, 0x01},
+	/* FSIN0 source. */
+	{0x000A, 0x05},
+	{0x000B, 0x00},
+	/* FSIN0 delay. */
+	{0x0030, 0x02},
+	{0x0031, 0x00},
+	{0x0032, 0x00},
+	{0x0033, 0x00},
+	/* FSIN1 delay. */
+	{0x0038, 0x02},
+	{0x0039, 0x00},
+	{0x003A, 0x00},
+	{0x003B, 0x00},
+	/* FSIN0 length. */
+	{0x0070, 0x2C},
+	{0x0071, 0x01},
+	{0x0072, 0x00},
+	{0x0073, 0x00},
+	/* FSIN1 length. */
+	{0x0074, 0x64},
+	{0x0075, 0x00},
+	{0x0076, 0x00},
+	{0x0077, 0x00},
+	{0x0000, 0x14},
+	{0x0001, 0x00},
+	{0x0002, 0x00},
+	{0x0003, 0x00},
+	/*
+	 * Load fsin0,load fsin1,load other,
+	 * It will be cleared automatically.
+	 */
+	{0x0004, 0x32},
+	{0x0005, 0x00},
+	{0x0006, 0x00},
+	{0x0007, 0x00},
+	{0xfffe, 0x80},
+	/* Sensor FSIN. */
+	{0x0081, 0x00},
+	/* ov10640 FSIN enable */
+	{0xfffe, 0x19},
+	{0x5000, 0x00},
+	{0x5001, 0x30},
+	{0x5002, 0x8c},
+	{0x5003, 0xb2},
+	{0xfffe, 0x80},
+	{0x00c0, 0xc1},
+	/* ov10640 HFLIP=1 by default */
+	{0xfffe, 0x19},
+	{0x5000, 0x01},
+	{0x5001, 0x00},
+	{0xfffe, 0x80},
+	{0x00c0, 0xdc},
+};
+
+static int ov490_read(struct rdacm21_device *dev, u16 reg, u8 *val)
+{
+	u8 buf[2] = { reg >> 8, reg & 0xff };
+	int ret;
+
+	ret = i2c_master_send(dev->isp, buf, 2);
+	if (ret < 0) {
+		dev_err(dev->dev, "%s: register 0x%04x read failed (%d)\n",
+			__func__, reg, ret);
+		return ret;
+	}
+
+	ret = i2c_master_recv(dev->isp, val, 1);
+	if (ret < 0) {
+		dev_err(dev->dev, "%s: register 0x%04x read failed (%d)\n",
+			__func__, reg, ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int ov490_write(struct rdacm21_device *dev, u16 reg, u8 val)
+{
+	u8 buf[3] = { reg >> 8, reg & 0xff, val };
+	int ret;
+
+	ret = i2c_master_send(dev->isp, buf, 3);
+	if (ret < 0) {
+		dev_err(dev->dev, "%s: register 0x%04x write failed (%d)\n",
+			__func__, reg, ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int rdacm21_s_stream(struct v4l2_subdev *sd, int enable)
+{
+	struct rdacm21_device *dev = sd_to_rdacm21(sd);
+
+	/*
+	 * Enable serial link now that the ISP provides a valid pixel clock
+	 * to start serializing video data on the GMSL link.
+	 */
+	return max9271_set_serial_link(dev->serializer, enable);
+}
+
+static int rdacm21_enum_mbus_code(struct v4l2_subdev *sd,
+				  struct v4l2_subdev_pad_config *cfg,
+				  struct v4l2_subdev_mbus_code_enum *mbus_enum)
+{
+	if (mbus_enum->index > 0)
+		return -EINVAL;
+
+	mbus_enum->code = MEDIA_BUS_FMT_YUYV8_1X16;
+
+	return 0;
+}
+
+static int rdacm21_get_fmt(struct v4l2_subdev *sd,
+			   struct v4l2_subdev_pad_config *cfg,
+			   struct v4l2_subdev_format *format)
+{
+	struct v4l2_mbus_framefmt *mf = &format->format;
+	struct rdacm21_device *dev = sd_to_rdacm21(sd);
+
+	mf->width		= dev->fmt.width;
+	mf->height		= dev->fmt.height;
+	mf->code		= MEDIA_BUS_FMT_YUYV8_1X16;
+	mf->colorspace		= V4L2_COLORSPACE_SRGB;
+	mf->field		= V4L2_FIELD_NONE;
+	mf->ycbcr_enc		= V4L2_YCBCR_ENC_601;
+	mf->quantization	= V4L2_QUANTIZATION_FULL_RANGE;
+	mf->xfer_func		= V4L2_XFER_FUNC_NONE;
+
+	return 0;
+}
+
+static struct v4l2_subdev_video_ops rdacm21_video_ops = {
+	.s_stream	= rdacm21_s_stream,
+};
+
+static const struct v4l2_subdev_pad_ops rdacm21_subdev_pad_ops = {
+	.enum_mbus_code = rdacm21_enum_mbus_code,
+	.get_fmt	= rdacm21_get_fmt,
+	.set_fmt	= rdacm21_get_fmt,
+};
+
+static struct v4l2_subdev_ops rdacm21_subdev_ops = {
+	.video		= &rdacm21_video_ops,
+	.pad		= &rdacm21_subdev_pad_ops,
+};
+
+static int ov490_initialize(struct rdacm21_device *dev)
+{
+	unsigned int ov490_pid_retry = 20;
+	unsigned int timeout;
+	u8 pid, ver, val;
+	unsigned int i;
+	int ret;
+
+	/* Read OV490 ID to test communications. */
+pid_retry:
+	ret = ov490_write(dev, 0xfffd, 0x80);
+	ret = ov490_write(dev, 0xfffe, 0x80);
+	usleep_range(100, 150);
+
+	ret = ov490_read(dev, OV490_PID, &pid);
+	if (ret < 0) {
+		/* Give OV490 more cycles to exit from reset. */
+		if (ov490_pid_retry--) {
+			usleep_range(500, 1000);
+			goto pid_retry;
+		}
+
+		dev_err(dev->dev, "OV490 PID read failed (%d)\n", ret);
+		return ret;
+	}
+
+	ret = ov490_read(dev, OV490_VER, &ver);
+	if (ret < 0) {
+		dev_err(dev->dev, "OV490 VERSION read failed (%d)\n", ret);
+		return ret;
+	}
+
+	if (OV490_ID(pid, ver) != OV490_ID_VAL) {
+		dev_err(dev->dev, "OV490 ID mismatch: (0x%04x)\n",
+			OV490_ID(pid, ver));
+		return -ENODEV;
+	}
+
+	/* Wait for firmware boot by reading streamon status. */
+	ov490_write(dev, 0xfffd, 0x80);
+	ov490_write(dev, 0xfffe, 0x29);
+	usleep_range(100, 150);
+	for (timeout = 300; timeout > 0; timeout--) {
+		ov490_read(dev, 0xd000, &val);
+		if (val == 0x0c)
+			break;
+		mdelay(1);
+	}
+	if (!timeout) {
+		dev_err(dev->dev, "Timeout firmware boot wait\n");
+		return -ENODEV;
+	}
+	dev_dbg(dev->dev, "Firmware booted in %u msec\n", 300 - timeout);
+
+	/* Read OV10640 ID to test communications. */
+	ov490_write(dev, 0xfffd, 0x80);
+	ov490_write(dev, 0xfffe, 0x19);
+	usleep_range(100, 150);
+
+	ov490_write(dev, 0x5000, 0x01);
+	ov490_write(dev, 0x5001, 0x30);
+	ov490_write(dev, 0x5002, 0x0a);
+
+	ov490_write(dev, 0xfffe, 0x80);
+	usleep_range(100, 150);
+	ov490_write(dev, 0xc0, 0xc1);
+	ov490_write(dev, 0xfffe, 0x19);
+	usleep_range(1000, 1500);
+	ov490_read(dev, 0x5000, &val);
+	if (val != OV10640_ID_LOW) {
+		dev_err(dev->dev, "OV10640 ID mismatch: (0x%02x)\n", val);
+		return -ENODEV;
+	}
+	dev_dbg(dev->dev, "OV10640 ID = 0x%2x\n", val);
+
+	for (i = 0; i < ARRAY_SIZE(ov490_regs_wizard); ++i) {
+		ret = ov490_write(dev, ov490_regs_wizard[i].reg,
+				  ov490_regs_wizard[i].val);
+		if (ret < 0) {
+			dev_err(dev->dev,
+				"%s: register %u (0x%04x) write failed (%d)\n",
+				__func__, i, ov490_regs_wizard[i].reg, ret);
+			return -EIO;
+		}
+
+		usleep_range(100, 150);
+	}
+
+	/*
+	 * The ISP is programmed with the content of a serial flash memory.
+	 * Read the firmware configuration to reflect it through the V4L2 APIs.
+	 */
+	ov490_write(dev, 0xfffd, 0x80);
+	ov490_write(dev, 0xfffe, 0x82);
+	usleep_range(100, 150);
+	ov490_read(dev, OV490_ISP_HSIZE_HIGH, &val);
+	dev->fmt.width = (val & 0xf) << 8;
+	ov490_read(dev, OV490_ISP_HSIZE_LOW, &val);
+	dev->fmt.width |= (val & 0xff);
+
+	ov490_read(dev, OV490_ISP_VSIZE_HIGH, &val);
+	dev->fmt.height = (val & 0xf) << 8;
+	ov490_read(dev, OV490_ISP_VSIZE_LOW, &val);
+	dev->fmt.height |= val & 0xff;
+
+	/* Set bus width to 12 bits [0:11] */
+	ov490_write(dev, 0xfffd, 0x80);
+	ov490_write(dev, 0xfffe, 0x28);
+	usleep_range(100, 150);
+	ov490_write(dev, 0x6009, 0x10);
+
+	dev_info(dev->dev, "Identified RDACM21 camera module\n");
+
+	return 0;
+}
+
+static int rdacm21_initialize(struct rdacm21_device *dev)
+{
+	int ret;
+
+	/* Verify communication with the MAX9271: ping to wakeup. */
+	dev->serializer->client->addr = MAX9271_DEFAULT_ADDR;
+	i2c_smbus_read_byte(dev->serializer->client);
+
+	/* Serial link disabled during config as it needs a valid pixel clk. */
+	ret = max9271_set_serial_link(dev->serializer, false);
+	if (ret)
+		return ret;
+
+	/* Set GPO high to hold OV490 in reset during max9271 configuration. */
+	ret = max9271_set_gpios(dev->serializer, MAX9271_GPO);
+	if (ret)
+		return ret;
+
+	/* Configure I2C bus at 105Kbps speed and configure GMSL link. */
+	ret = max9271_configure_i2c(dev->serializer,
+				    MAX9271_I2CSLVSH_469NS_234NS |
+				    MAX9271_I2CSLVTO_1024US |
+				    MAX9271_I2CMSTBT_105KBPS);
+	if (ret)
+		return ret;
+
+	ret = max9271_configure_gmsl_link(dev->serializer);
+	if (ret)
+		return ret;
+
+	ret = max9271_set_address(dev->serializer, dev->addrs[0]);
+	if (ret)
+		return ret;
+	dev->serializer->client->addr = dev->addrs[0];
+
+	/*
+	 * Release OV490 from reset and program address translation
+	 * before performing OV490 configuration.
+	 */
+	ret = max9271_clear_gpios(dev->serializer, MAX9271_GPO);
+	if (ret)
+		return ret;
+
+	ret = max9271_set_translation(dev->serializer, dev->addrs[1],
+				      OV490_I2C_ADDRESS);
+	if (ret)
+		return ret;
+	dev->isp->addr = dev->addrs[1];
+
+	ret = ov490_initialize(dev);
+	if (ret)
+		return ret;
+
+	/*
+	 * Set reverse channel high threshold to increase noise immunity.
+	 *
+	 * This should be compensated by increasing the reverse channel
+	 * amplitude on the remote deserializer side.
+	 */
+	ret = max9271_set_high_threshold(dev->serializer, true);
+	if (ret)
+		return ret;
+	dev->high_threshold = true;
+
+	return 0;
+}
+
+static int rdacm21_probe(struct i2c_client *client)
+{
+	struct rdacm21_device *dev;
+	struct fwnode_handle *ep;
+	int ret;
+
+	dev = devm_kzalloc(&client->dev, sizeof(*dev), GFP_KERNEL);
+	if (!dev)
+		return -ENOMEM;
+	dev->dev = &client->dev;
+
+	dev->serializer = devm_kzalloc(&client->dev, sizeof(*dev->serializer),
+				       GFP_KERNEL);
+	if (!dev->serializer)
+		return -ENOMEM;
+
+	dev->serializer->client = client;
+
+	ret = of_property_read_u32_array(client->dev.of_node, "reg",
+					 dev->addrs, 2);
+	if (ret < 0) {
+		dev_err(dev->dev, "Invalid DT reg property: %d\n", ret);
+		return -EINVAL;
+	}
+
+	/* Create the dummy I2C client for the sensor. */
+	dev->isp = i2c_new_dummy_device(client->adapter, OV490_I2C_ADDRESS);
+	if (IS_ERR(dev->isp))
+		return PTR_ERR(dev->isp);
+
+	ret = rdacm21_initialize(dev);
+	if (ret < 0)
+		goto error;
+
+	/* Initialize and register the subdevice. */
+	v4l2_i2c_subdev_init(&dev->sd, client, &rdacm21_subdev_ops);
+	dev->sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
+
+	v4l2_ctrl_handler_init(&dev->ctrls, 1);
+	v4l2_ctrl_new_std(&dev->ctrls, NULL, V4L2_CID_PIXEL_RATE,
+			  OV10640_PIXEL_RATE, OV10640_PIXEL_RATE, 1,
+			  OV10640_PIXEL_RATE);
+	dev->sd.ctrl_handler = &dev->ctrls;
+
+	ret = dev->ctrls.error;
+	if (ret)
+		goto error_free_ctrls;
+
+	dev->pad.flags = MEDIA_PAD_FL_SOURCE;
+	dev->sd.entity.flags |= MEDIA_ENT_F_CAM_SENSOR;
+	ret = media_entity_pads_init(&dev->sd.entity, 1, &dev->pad);
+	if (ret < 0)
+		goto error_free_ctrls;
+
+	ep = fwnode_graph_get_next_endpoint(dev_fwnode(&client->dev), NULL);
+	if (!ep) {
+		dev_err(&client->dev, "Unable to get endpoint in node %pOF\n",
+			client->dev.of_node);
+		ret = -ENOENT;
+		goto error_free_ctrls;
+	}
+	dev->sd.fwnode = ep;
+
+	ret = v4l2_async_register_subdev(&dev->sd);
+	if (ret)
+		goto error_put_node;
+
+	return 0;
+
+error_put_node:
+	fwnode_handle_put(dev->sd.fwnode);
+error_free_ctrls:
+	v4l2_ctrl_handler_free(&dev->ctrls);
+error:
+	i2c_unregister_device(dev->isp);
+
+	return ret;
+}
+
+static int rdacm21_remove(struct i2c_client *client)
+{
+	struct rdacm21_device *dev = i2c_to_rdacm21(client);
+
+	fwnode_handle_put(dev->sd.fwnode);
+	v4l2_async_unregister_subdev(&dev->sd);
+	i2c_unregister_device(dev->isp);
+
+	return 0;
+}
+
+static const struct of_device_id rdacm21_of_ids[] = {
+	{ .compatible = "imi,rdacm21" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, rdacm21_of_ids);
+
+static struct i2c_driver rdacm21_i2c_driver = {
+	.driver	= {
+		.name	= "rdacm21",
+		.of_match_table = rdacm21_of_ids,
+	},
+	.probe_new	= rdacm21_probe,
+	.remove		= rdacm21_remove,
+};
+
+module_i2c_driver(rdacm21_i2c_driver);
+
+MODULE_DESCRIPTION("GMSL Camera driver for RDACM21");
+MODULE_AUTHOR("Jacopo Mondi, Kieran Bingham, Laurent Pinchart, Niklas Söderlund, Vladimir Barinov");
+MODULE_LICENSE("GPL v2");
-- 
2.28.0