The MAX9286 is a 4-channel GMSL deserializer with coax or STP input and
CSI-2 output. The device supports multicamera streaming applications,
and features the ability to synchronise the attached cameras.

CSI-2 output can be configured with 1 to 4 lanes, and a control channel
is supported over I2C, which implements an I2C mux to facilitate
communications with connected cameras across the reverse control
channel.

Signed-off-by: Jacopo Mondi <jacopo+rene...@jmondi.org>
Signed-off-by: Kieran Bingham <kieran.bingham+rene...@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart+rene...@ideasonboard.com>
Signed-off-by: Niklas Söderlund <niklas.soderlund+rene...@ragnatech.se>

--
v2:
 - Fix MAINTAINERS entry

This posting is released with the following modifications to work
without Sakari's VC developments:
 - max9286_g_mbus_config() re-instated
 - max9286_get_frame_desc() is not bus/csi aware
 - max9286_{get,set}_routing() removed

v3:
 - Initialise notifier with v4l2_async_notifier_init
 - Update for new mbus csi2 format V4L2_MBUS_CSI2_DPHY

v4: - Re-introduce required code to function with the VC series.

 - Implement max9286_get_routing, max9286_set_routing
 - Remove max9286_g_mbus_config

v5: (internal release)
 - Fix printk formatting for hex value
 - max9286->sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE (add |)
 - MEDIA_ENT_F_PROC_VIDEO_PIXEL_FORMATTER -> MEDIA_ENT_F_VID_IF_BRIDGE
 - Remove 'device is bound' workaround

v6:
 - v4l2_subdev_krouting instead of v4l2_subdev_routing separated
   to allow integration without the VC/V4L2-Mux series.
 - convert sd_to_max9286 to inline function
 - rename max9286_device to max9286_priv
 - Cleanup the v4l2_async_notifier
 - Extend MODULE_AUTHOR
 - Replace of_graph_get_endpoint_by_regs with fwnode_graph_get_endpoint_by_id
 - Pass default bus type when parsing fwnode endpoint (Manivannan Sadhasivam)
 - Use new YAML file reference in MAINTAINERS
 - Parse new i2c-mux node in max9286_get_i2c_by_id
   (This could/should be refactored to parse these separately first)
 - Spelling and calculation fixes in the FSYNC_LOCKED check comments
 - Identify each enabled i2c-mux channel in a single pass
 - max9286: Improve mux-state readbility [v2]
 - Fix frame sync lock durations
 - Add comment to describe /why/ we must open the mux in s_stream
 - use -EXDEV as return code for failed link synchronisation.
 - Fix reference counting of the dt nodeS
 - Convert to probe_new for I2C
 - Remove redundant max9286_i2c_mux_state
 - Provide optional enable-gpio (max9286-pwdn)

v7:
 [Kieran]
 - Ensure powerdown lines are optional
 - Add a 4ms power-up delay
 - Add max9286_check_config_link() to core
 - Add GPIO chip controller for GPIO0OUT and GPIO1OUT
 - Fix GPIO registration
 - max9286: Split out async registration
   (fixes regulator -EPROBE_DEFERs failures)
 - Collect all V4L2 registrations
 - balance v4l2_async refcnting
 - Rename max9286_v4l2_async_ => max9286_v4l2_notifier_

 [Jacopo]
 - Remove redundanct MAXIM_I2C_SPEED macros
 - Move notifiers operations
 - Add delay after reverse channel reconfiguration
 - Move link setup to completion
 - Fix up max9286_check_config_link() implementation
 - Remove redundant dual configuration of reverse channel

v8:

[Kieran]
 - Update the bound_sources mask on unbind
 - Convert probe kzalloc usage to devm_ variant
 - Fix up cleanup path from GPIO PowerDown registration
 - cleanup GPIO device registration fail path
 - Convert to use devm_regulator_get()
 - Fit max9286_parse_dt print on one line
 - Move multi-device workarounds out of upstream driver
 - Remove I2C mod-table
 - Lock format changes
 - Describe pad index usage
 - Remove poc_enabled workaround
 - Rename the max9286_gpio to be more explicit on it's actions.
 - Move max9286_init_format call
 - Rework probe sequence and simplify error paths.
 - Simplify i2c comments
 - Implement Pixelrate control
 - Disable overlap window

[Jacopo]
 - Adapt Kconfig to latest upstream changes
 - Put of node on error
 - Calculate pixel rate
 - Simplify overlap window disablement

v9:

[Kieran]
 - Kconfig: Depend on OF
 - Re-sort addition to Makefile

v10:

[Kieran]
 - Use the same default mbus_fmt everywhere
 - Don't provide GPIO names
 - Fix dev->of_node refcnting
 - Fix whitespace indent
 - Use single sample per pixel
 - Remove redundant DPHY check
 - Remove redundant v4l2_fwnode_endpoint_free call
 - Validate link formats
---
 MAINTAINERS                 |   10 +
 drivers/media/i2c/Kconfig   |   13 +
 drivers/media/i2c/Makefile  |    1 +
 drivers/media/i2c/max9286.c | 1320 +++++++++++++++++++++++++++++++++++
 4 files changed, 1344 insertions(+)
 create mode 100644 drivers/media/i2c/max9286.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 791d2a862e41..7534df72033f 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -10274,6 +10274,16 @@ F:     Documentation/hwmon/max6697.rst
 F:     drivers/hwmon/max6697.c
 F:     include/linux/platform_data/max6697.h
 
+MAX9286 QUAD GMSL DESERIALIZER DRIVER
+M:     Jacopo Mondi <jacopo+rene...@jmondi.org>
+M:     Kieran Bingham <kieran.bingham+rene...@ideasonboard.com>
+M:     Laurent Pinchart <laurent.pinchart+rene...@ideasonboard.com>
+M:     Niklas Söderlund <niklas.soderlund+rene...@ragnatech.se>
+L:     linux-me...@vger.kernel.org
+S:     Maintained
+F:     Documentation/devicetree/bindings/media/i2c/maxim,max9286.yaml
+F:     drivers/media/i2c/max9286.c
+
 MAX9860 MONO AUDIO VOICE CODEC DRIVER
 M:     Peter Rosin <p...@axentia.se>
 L:     alsa-de...@alsa-project.org (moderated for non-subscribers)
diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
index da11036ad804..0a083407aa3e 100644
--- a/drivers/media/i2c/Kconfig
+++ b/drivers/media/i2c/Kconfig
@@ -464,6 +464,19 @@ config VIDEO_VPX3220
          To compile this driver as a module, choose M here: the
          module will be called vpx3220.
 
+config VIDEO_MAX9286
+       tristate "Maxim MAX9286 GMSL deserializer support"
+       depends on I2C && I2C_MUX
+       depends on OF
+       select V4L2_FWNODE
+       select VIDEO_V4L2_SUBDEV_API
+       select MEDIA_CONTROLLER
+       help
+         This driver supports the Maxim MAX9286 GMSL deserializer.
+
+         To compile this driver as a module, choose M here: the
+         module will be called max9286.
+
 comment "Video and audio decoders"
 
 config VIDEO_SAA717X
diff --git a/drivers/media/i2c/Makefile b/drivers/media/i2c/Makefile
index 993acab81b2c..c8010d77e1a3 100644
--- a/drivers/media/i2c/Makefile
+++ b/drivers/media/i2c/Makefile
@@ -118,6 +118,7 @@ obj-$(CONFIG_VIDEO_IMX274)  += imx274.o
 obj-$(CONFIG_VIDEO_IMX290)     += imx290.o
 obj-$(CONFIG_VIDEO_IMX319)     += imx319.o
 obj-$(CONFIG_VIDEO_IMX355)     += imx355.o
+obj-$(CONFIG_VIDEO_MAX9286)    += max9286.o
 obj-$(CONFIG_VIDEO_ST_MIPID02) += st-mipid02.o
 
 obj-$(CONFIG_SDR_MAX2175) += max2175.o
diff --git a/drivers/media/i2c/max9286.c b/drivers/media/i2c/max9286.c
new file mode 100644
index 000000000000..47f280518fdb
--- /dev/null
+++ b/drivers/media/i2c/max9286.c
@@ -0,0 +1,1320 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Maxim MAX9286 GMSL Deserializer Driver
+ *
+ * Copyright (C) 2017-2019 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/device.h>
+#include <linux/fwnode.h>
+#include <linux/gpio/consumer.h>
+#include <linux/gpio/driver.h>
+#include <linux/i2c.h>
+#include <linux/i2c-mux.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of_graph.h>
+#include <linux/regulator/consumer.h>
+#include <linux/slab.h>
+
+#include <media/v4l2-async.h>
+#include <media/v4l2-ctrls.h>
+#include <media/v4l2-device.h>
+#include <media/v4l2-fwnode.h>
+#include <media/v4l2-subdev.h>
+
+/* Register 0x00 */
+#define MAX9286_MSTLINKSEL_AUTO                (7 << 5)
+#define MAX9286_MSTLINKSEL(n)          ((n) << 5)
+#define MAX9286_EN_VS_GEN              BIT(4)
+#define MAX9286_LINKEN(n)              (1 << (n))
+/* Register 0x01 */
+#define MAX9286_FSYNCMODE_ECU          (3 << 6)
+#define MAX9286_FSYNCMODE_EXT          (2 << 6)
+#define MAX9286_FSYNCMODE_INT_OUT      (1 << 6)
+#define MAX9286_FSYNCMODE_INT_HIZ      (0 << 6)
+#define MAX9286_GPIEN                  BIT(5)
+#define MAX9286_ENLMO_RSTFSYNC         BIT(2)
+#define MAX9286_FSYNCMETH_AUTO         (2 << 0)
+#define MAX9286_FSYNCMETH_SEMI_AUTO    (1 << 0)
+#define MAX9286_FSYNCMETH_MANUAL       (0 << 0)
+#define MAX9286_REG_FSYNC_PERIOD_L     0x06
+#define MAX9286_REG_FSYNC_PERIOD_M     0x07
+#define MAX9286_REG_FSYNC_PERIOD_H     0x08
+/* Register 0x0a */
+#define MAX9286_FWDCCEN(n)             (1 << ((n) + 4))
+#define MAX9286_REVCCEN(n)             (1 << (n))
+/* Register 0x0c */
+#define MAX9286_HVEN                   BIT(7)
+#define MAX9286_EDC_6BIT_HAMMING       (2 << 5)
+#define MAX9286_EDC_6BIT_CRC           (1 << 5)
+#define MAX9286_EDC_1BIT_PARITY                (0 << 5)
+#define MAX9286_DESEL                  BIT(4)
+#define MAX9286_INVVS                  BIT(3)
+#define MAX9286_INVHS                  BIT(2)
+#define MAX9286_HVSRC_D0               (2 << 0)
+#define MAX9286_HVSRC_D14              (1 << 0)
+#define MAX9286_HVSRC_D18              (0 << 0)
+/* Register 0x0f */
+#define MAX9286_0X0F_RESERVED          BIT(3)
+/* Register 0x12 */
+#define MAX9286_CSILANECNT(n)          (((n) - 1) << 6)
+#define MAX9286_CSIDBL                 BIT(5)
+#define MAX9286_DBL                    BIT(4)
+#define MAX9286_DATATYPE_USER_8BIT     (11 << 0)
+#define MAX9286_DATATYPE_USER_YUV_12BIT        (10 << 0)
+#define MAX9286_DATATYPE_USER_24BIT    (9 << 0)
+#define MAX9286_DATATYPE_RAW14         (8 << 0)
+#define MAX9286_DATATYPE_RAW11         (7 << 0)
+#define MAX9286_DATATYPE_RAW10         (6 << 0)
+#define MAX9286_DATATYPE_RAW8          (5 << 0)
+#define MAX9286_DATATYPE_YUV422_10BIT  (4 << 0)
+#define MAX9286_DATATYPE_YUV422_8BIT   (3 << 0)
+#define MAX9286_DATATYPE_RGB555                (2 << 0)
+#define MAX9286_DATATYPE_RGB565                (1 << 0)
+#define MAX9286_DATATYPE_RGB888                (0 << 0)
+/* Register 0x15 */
+#define MAX9286_VC(n)                  ((n) << 5)
+#define MAX9286_VCTYPE                 BIT(4)
+#define MAX9286_CSIOUTEN               BIT(3)
+#define MAX9286_0X15_RESV              (3 << 0)
+/* Register 0x1b */
+#define MAX9286_SWITCHIN(n)            (1 << ((n) + 4))
+#define MAX9286_ENEQ(n)                        (1 << (n))
+/* Register 0x27 */
+#define MAX9286_LOCKED                 BIT(7)
+/* Register 0x31 */
+#define MAX9286_FSYNC_LOCKED           BIT(6)
+/* Register 0x34 */
+#define MAX9286_I2CLOCACK              BIT(7)
+#define MAX9286_I2CSLVSH_1046NS_469NS  (3 << 5)
+#define MAX9286_I2CSLVSH_938NS_352NS   (2 << 5)
+#define MAX9286_I2CSLVSH_469NS_234NS   (1 << 5)
+#define MAX9286_I2CSLVSH_352NS_117NS   (0 << 5)
+#define MAX9286_I2CMSTBT_837KBPS       (7 << 2)
+#define MAX9286_I2CMSTBT_533KBPS       (6 << 2)
+#define MAX9286_I2CMSTBT_339KBPS       (5 << 2)
+#define MAX9286_I2CMSTBT_173KBPS       (4 << 2)
+#define MAX9286_I2CMSTBT_105KBPS       (3 << 2)
+#define MAX9286_I2CMSTBT_84KBPS                (2 << 2)
+#define MAX9286_I2CMSTBT_28KBPS                (1 << 2)
+#define MAX9286_I2CMSTBT_8KBPS         (0 << 2)
+#define MAX9286_I2CSLVTO_NONE          (3 << 0)
+#define MAX9286_I2CSLVTO_1024US                (2 << 0)
+#define MAX9286_I2CSLVTO_256US         (1 << 0)
+#define MAX9286_I2CSLVTO_64US          (0 << 0)
+/* Register 0x3b */
+#define MAX9286_REV_TRF(n)             ((n) << 4)
+#define MAX9286_REV_AMP(n)             ((((n) - 30) / 10) << 1) /* in mV */
+#define MAX9286_REV_AMP_X              BIT(0)
+/* Register 0x3f */
+#define MAX9286_EN_REV_CFG             BIT(6)
+#define MAX9286_REV_FLEN(n)            ((n) - 20)
+/* Register 0x49 */
+#define MAX9286_VIDEO_DETECT_MASK      0x0f
+/* Register 0x69 */
+#define MAX9286_LFLTBMONMASKED         BIT(7)
+#define MAX9286_LOCKMONMASKED          BIT(6)
+#define MAX9286_AUTOCOMBACKEN          BIT(5)
+#define MAX9286_AUTOMASKEN             BIT(4)
+#define MAX9286_MASKLINK(n)            ((n) << 0)
+
+/*
+ * The sink and source pads are created to match the OF graph port numbers so
+ * that their indexes can be used interchangeably.
+ */
+#define MAX9286_NUM_GMSL               4
+#define MAX9286_N_SINKS                        4
+#define MAX9286_N_PADS                 5
+#define MAX9286_SRC_PAD                        4
+
+struct max9286_source {
+       struct v4l2_async_subdev asd;
+       struct v4l2_subdev *sd;
+       struct fwnode_handle *fwnode;
+};
+
+#define asd_to_max9286_source(_asd) \
+       container_of(_asd, struct max9286_source, asd)
+
+struct max9286_priv {
+       struct i2c_client *client;
+       struct gpio_desc *gpiod_pwdn;
+       struct v4l2_subdev sd;
+       struct media_pad pads[MAX9286_N_PADS];
+       struct regulator *regulator;
+
+       struct gpio_chip gpio;
+       u8 gpio_state;
+
+       struct i2c_mux_core *mux;
+       unsigned int mux_channel;
+       bool mux_open;
+
+       struct v4l2_ctrl_handler ctrls;
+       struct v4l2_ctrl *pixelrate;
+
+       struct v4l2_mbus_framefmt fmt[MAX9286_N_SINKS];
+
+       /* Protects controls and fmt structures */
+       struct mutex mutex;
+
+       unsigned int nsources;
+       unsigned int source_mask;
+       unsigned int route_mask;
+       unsigned int bound_sources;
+       unsigned int csi2_data_lanes;
+       struct max9286_source sources[MAX9286_NUM_GMSL];
+       struct v4l2_async_notifier notifier;
+};
+
+static struct max9286_source *next_source(struct max9286_priv *priv,
+                                         struct max9286_source *source)
+{
+       if (!source)
+               source = &priv->sources[0];
+       else
+               source++;
+
+       for (; source < &priv->sources[MAX9286_NUM_GMSL]; source++) {
+               if (source->fwnode)
+                       return source;
+       }
+
+       return NULL;
+}
+
+#define for_each_source(priv, source) \
+       for ((source) = NULL; ((source) = next_source((priv), (source))); )
+
+#define to_index(priv, source) ((source) - &(priv)->sources[0])
+
+static inline struct max9286_priv *sd_to_max9286(struct v4l2_subdev *sd)
+{
+       return container_of(sd, struct max9286_priv, sd);
+}
+
+/* 
-----------------------------------------------------------------------------
+ * I2C IO
+ */
+
+static int max9286_read(struct max9286_priv *priv, u8 reg)
+{
+       int ret;
+
+       ret = i2c_smbus_read_byte_data(priv->client, reg);
+       if (ret < 0)
+               dev_err(&priv->client->dev,
+                       "%s: register 0x%02x read failed (%d)\n",
+                       __func__, reg, ret);
+
+       return ret;
+}
+
+static int max9286_write(struct max9286_priv *priv, u8 reg, u8 val)
+{
+       int ret;
+
+       ret = i2c_smbus_write_byte_data(priv->client, reg, val);
+       if (ret < 0)
+               dev_err(&priv->client->dev,
+                       "%s: register 0x%02x write failed (%d)\n",
+                       __func__, reg, ret);
+
+       return ret;
+}
+
+/* 
-----------------------------------------------------------------------------
+ * I2C Multiplexer
+ */
+
+static void max9286_i2c_mux_configure(struct max9286_priv *priv, u8 conf)
+{
+       max9286_write(priv, 0x0a, conf);
+
+       /*
+        * We must sleep after any change to the forward or reverse channel
+        * configuration.
+        */
+       usleep_range(3000, 5000);
+}
+
+static void max9286_i2c_mux_open(struct max9286_priv *priv)
+{
+       /* Open all channels on the MAX9286 */
+       max9286_i2c_mux_configure(priv, 0xff);
+
+       priv->mux_open = true;
+}
+
+static void max9286_i2c_mux_close(struct max9286_priv *priv)
+{
+       /*
+        * Ensure that both the forward and reverse channel are disabled on the
+        * mux, and that the channel ID is invalidated to ensure we reconfigure
+        * on the next max9286_i2c_mux_select() call.
+        */
+       max9286_i2c_mux_configure(priv, 0x00);
+
+       priv->mux_open = false;
+       priv->mux_channel = -1;
+}
+
+static int max9286_i2c_mux_select(struct i2c_mux_core *muxc, u32 chan)
+{
+       struct max9286_priv *priv = i2c_mux_priv(muxc);
+
+       /* Channel select is disabled when configured in the opened state. */
+       if (priv->mux_open)
+               return 0;
+
+       if (priv->mux_channel == chan)
+               return 0;
+
+       priv->mux_channel = chan;
+
+       max9286_i2c_mux_configure(priv,
+                                 MAX9286_FWDCCEN(chan) |
+                                 MAX9286_REVCCEN(chan));
+
+       return 0;
+}
+
+static int max9286_i2c_mux_init(struct max9286_priv *priv)
+{
+       struct max9286_source *source;
+       int ret;
+
+       if (!i2c_check_functionality(priv->client->adapter,
+                                    I2C_FUNC_SMBUS_WRITE_BYTE_DATA))
+               return -ENODEV;
+
+       priv->mux = i2c_mux_alloc(priv->client->adapter, &priv->client->dev,
+                                 priv->nsources, 0, I2C_MUX_LOCKED,
+                                 max9286_i2c_mux_select, NULL);
+       if (!priv->mux)
+               return -ENOMEM;
+
+       priv->mux->priv = priv;
+
+       for_each_source(priv, source) {
+               unsigned int index = to_index(priv, source);
+
+               ret = i2c_mux_add_adapter(priv->mux, 0, index, 0);
+               if (ret < 0)
+                       goto error;
+       }
+
+       return 0;
+
+error:
+       i2c_mux_del_adapters(priv->mux);
+       return ret;
+}
+
+static void max9286_configure_i2c(struct max9286_priv *priv, bool localack)
+{
+       u8 config = MAX9286_I2CSLVSH_469NS_234NS | MAX9286_I2CSLVTO_1024US |
+                   MAX9286_I2CMSTBT_105KBPS;
+
+       if (localack)
+               config |= MAX9286_I2CLOCACK;
+
+       max9286_write(priv, 0x34, config);
+       usleep_range(3000, 5000);
+}
+
+/*
+ * max9286_check_video_links() - Make sure video links are detected and locked
+ *
+ * Performs safety checks on video link status. Make sure they are detected
+ * and all enabled links are locked.
+ *
+ * Returns 0 for success, -EIO for errors.
+ */
+static int max9286_check_video_links(struct max9286_priv *priv)
+{
+       unsigned int i;
+       int ret;
+
+       /*
+        * Make sure valid video links are detected.
+        * The delay is not characterized in de-serializer manual, wait up
+        * to 5 ms.
+        */
+       for (i = 0; i < 10; i++) {
+               ret = max9286_read(priv, 0x49);
+               if (ret < 0)
+                       return -EIO;
+
+               if ((ret & MAX9286_VIDEO_DETECT_MASK) == priv->source_mask)
+                       break;
+
+               usleep_range(350, 500);
+       }
+
+       if (i == 10) {
+               dev_err(&priv->client->dev,
+                       "Unable to detect video links: 0x%02x\n", ret);
+               return -EIO;
+       }
+
+       /* Make sure all enabled links are locked (4ms max). */
+       for (i = 0; i < 10; i++) {
+               ret = max9286_read(priv, 0x27);
+               if (ret < 0)
+                       return -EIO;
+
+               if (ret & MAX9286_LOCKED)
+                       break;
+
+               usleep_range(350, 450);
+       }
+
+       if (i == 10) {
+               dev_err(&priv->client->dev, "Not all enabled links locked\n");
+               return -EIO;
+       }
+
+       return 0;
+}
+
+/*
+ * max9286_check_config_link() - Detect and wait for configuration links
+ *
+ * Determine if the configuration channel is up and settled for a link.
+ *
+ * Returns 0 for success, -EIO for errors.
+ */
+static int max9286_check_config_link(struct max9286_priv *priv,
+                                    unsigned int source_mask)
+{
+       unsigned int conflink_mask = (source_mask & 0x0f) << 4;
+       unsigned int i;
+       int ret;
+
+       /*
+        * Make sure requested configuration links are detected.
+        * The delay is not characterized in the chip manual: wait up
+        * to 5 milliseconds.
+        */
+       for (i = 0; i < 10; i++) {
+               ret = max9286_read(priv, 0x49) & 0xf0;
+               if (ret < 0)
+                       return -EIO;
+
+               if (ret == conflink_mask)
+                       break;
+
+               usleep_range(350, 500);
+       }
+
+       if (ret != conflink_mask) {
+               dev_err(&priv->client->dev,
+                       "Unable to detect configuration links: 0x%02x expected 
0x%02x\n",
+                       ret, conflink_mask);
+               return -EIO;
+       }
+
+       dev_info(&priv->client->dev,
+                "Successfully detected configuration links after %u loops: 
0x%02x\n",
+                i, conflink_mask);
+
+       return 0;
+}
+
+/* 
-----------------------------------------------------------------------------
+ * V4L2 Subdev
+ */
+
+static int max9286_set_pixelrate(struct max9286_priv *priv)
+{
+       struct max9286_source *source = NULL;
+       u64 pixelrate = 0;
+
+       for_each_source(priv, source) {
+               struct v4l2_ctrl *ctrl;
+               u64 source_rate = 0;
+
+               /* Pixel rate is mandatory to be reported by sources. */
+               ctrl = v4l2_ctrl_find(source->sd->ctrl_handler,
+                                     V4L2_CID_PIXEL_RATE);
+               if (!ctrl) {
+                       pixelrate = 0;
+                       break;
+               }
+
+               /* All source must report the same pixel rate. */
+               source_rate = v4l2_ctrl_g_ctrl_int64(ctrl);
+               if (!pixelrate) {
+                       pixelrate = source_rate;
+               } else if (pixelrate != source_rate) {
+                       dev_err(&priv->client->dev,
+                               "Unable to calculate pixel rate\n");
+                       return -EINVAL;
+               }
+       }
+
+       if (!pixelrate) {
+               dev_err(&priv->client->dev,
+                       "No pixel rate control available in sources\n");
+               return -EINVAL;
+       }
+
+       /*
+        * The CSI-2 transmitter pixel rate is the single source rate multiplied
+        * by the number of available sources.
+        */
+       return v4l2_ctrl_s_ctrl_int64(priv->pixelrate,
+                                     pixelrate * priv->nsources);
+}
+
+static int max9286_notify_bound(struct v4l2_async_notifier *notifier,
+                               struct v4l2_subdev *subdev,
+                               struct v4l2_async_subdev *asd)
+{
+       struct max9286_priv *priv = sd_to_max9286(notifier->sd);
+       struct max9286_source *source = asd_to_max9286_source(asd);
+       unsigned int index = to_index(priv, source);
+       unsigned int src_pad;
+       int ret;
+
+       ret = media_entity_get_fwnode_pad(&subdev->entity,
+                                         source->fwnode,
+                                         MEDIA_PAD_FL_SOURCE);
+       if (ret < 0) {
+               dev_err(&priv->client->dev,
+                       "Failed to find pad for %s\n", subdev->name);
+               return ret;
+       }
+
+       priv->bound_sources |= BIT(index);
+       source->sd = subdev;
+       src_pad = ret;
+
+       ret = media_create_pad_link(&source->sd->entity, src_pad,
+                                   &priv->sd.entity, index,
+                                   MEDIA_LNK_FL_ENABLED |
+                                   MEDIA_LNK_FL_IMMUTABLE);
+       if (ret) {
+               dev_err(&priv->client->dev,
+                       "Unable to link %s:%u -> %s:%u\n",
+                       source->sd->name, src_pad, priv->sd.name, index);
+               return ret;
+       }
+
+       dev_dbg(&priv->client->dev, "Bound %s pad: %u on index %u\n",
+               subdev->name, src_pad, index);
+
+       /*
+        * We can only register v4l2_async_notifiers, which do not provide a
+        * means to register a complete callback. bound_sources allows us to
+        * identify when all remote serializers have completed their probe.
+        */
+       if (priv->bound_sources != priv->source_mask)
+               return 0;
+
+       /*
+        * All enabled sources have probed and enabled their reverse control
+        * channels:
+        *
+        * - Verify all configuration links are properly detected
+        * - Disable auto-ack as communication on the control channel are now
+        *   stable.
+        */
+       max9286_check_config_link(priv, priv->source_mask);
+
+       /*
+        * Re-configure I2C with local acknowledge disabled after cameras have
+        * probed.
+        */
+       max9286_configure_i2c(priv, false);
+
+       return max9286_set_pixelrate(priv);
+}
+
+static void max9286_notify_unbind(struct v4l2_async_notifier *notifier,
+                                 struct v4l2_subdev *subdev,
+                                 struct v4l2_async_subdev *asd)
+{
+       struct max9286_priv *priv = sd_to_max9286(notifier->sd);
+       struct max9286_source *source = asd_to_max9286_source(asd);
+       unsigned int index = to_index(priv, source);
+
+       source->sd = NULL;
+       priv->bound_sources &= ~BIT(index);
+}
+
+static const struct v4l2_async_notifier_operations max9286_notify_ops = {
+       .bound = max9286_notify_bound,
+       .unbind = max9286_notify_unbind,
+};
+
+static int max9286_v4l2_notifier_register(struct max9286_priv *priv)
+{
+       struct device *dev = &priv->client->dev;
+       struct max9286_source *source = NULL;
+       int ret;
+
+       if (!priv->nsources)
+               return 0;
+
+       v4l2_async_notifier_init(&priv->notifier);
+
+       for_each_source(priv, source) {
+               unsigned int i = to_index(priv, source);
+
+               source->asd.match_type = V4L2_ASYNC_MATCH_FWNODE;
+               source->asd.match.fwnode = source->fwnode;
+
+               ret = v4l2_async_notifier_add_subdev(&priv->notifier,
+                                                    &source->asd);
+               if (ret) {
+                       dev_err(dev, "Failed to add subdev for source %d", i);
+                       v4l2_async_notifier_cleanup(&priv->notifier);
+                       return ret;
+               }
+
+               /*
+                * Balance the reference counting handled through
+                * v4l2_async_notifier_cleanup()
+                */
+               fwnode_handle_get(source->fwnode);
+       }
+
+       priv->notifier.ops = &max9286_notify_ops;
+
+       ret = v4l2_async_subdev_notifier_register(&priv->sd, &priv->notifier);
+       if (ret) {
+               dev_err(dev, "Failed to register subdev_notifier");
+               v4l2_async_notifier_cleanup(&priv->notifier);
+               return ret;
+       }
+
+       return 0;
+}
+
+static void max9286_v4l2_notifier_unregister(struct max9286_priv *priv)
+{
+       if (!priv->nsources)
+               return;
+
+       v4l2_async_notifier_unregister(&priv->notifier);
+       v4l2_async_notifier_cleanup(&priv->notifier);
+}
+
+static int max9286_s_stream(struct v4l2_subdev *sd, int enable)
+{
+       struct max9286_priv *priv = sd_to_max9286(sd);
+       struct max9286_source *source;
+       unsigned int i;
+       bool sync = false;
+       int ret;
+
+       if (enable) {
+               /*
+                * The frame sync between cameras is transmitted across the
+                * reverse channel as GPIO. We must open all channels while
+                * streaming to allow this synchronisation signal to be shared.
+                */
+               max9286_i2c_mux_open(priv);
+
+               /* Start all cameras. */
+               for_each_source(priv, source) {
+                       ret = v4l2_subdev_call(source->sd, video, s_stream, 1);
+                       if (ret)
+                               return ret;
+               }
+
+               ret = max9286_check_video_links(priv);
+               if (ret)
+                       return ret;
+
+               /*
+                * Wait until frame synchronization is locked.
+                *
+                * Manual says frame sync locking should take ~6 VTS.
+                * From practical experience at least 8 are required. Give
+                * 12 complete frames time (~400ms at 30 fps) to achieve frame
+                * locking before returning error.
+                */
+               for (i = 0; i < 40; i++) {
+                       if (max9286_read(priv, 0x31) & MAX9286_FSYNC_LOCKED) {
+                               sync = true;
+                               break;
+                       }
+                       usleep_range(9000, 11000);
+               }
+
+               if (!sync) {
+                       dev_err(&priv->client->dev,
+                               "Failed to get frame synchronization\n");
+                       return -EXDEV; /* Invalid cross-device link */
+               }
+
+               /*
+                * Enable CSI output, VC set according to link number.
+                * Bit 7 must be set (chip manual says it's 0 and reserved).
+                */
+               max9286_write(priv, 0x15, 0x80 | MAX9286_VCTYPE |
+                             MAX9286_CSIOUTEN | MAX9286_0X15_RESV);
+       } else {
+               max9286_write(priv, 0x15, MAX9286_VCTYPE | MAX9286_0X15_RESV);
+
+               /* Stop all cameras. */
+               for_each_source(priv, source)
+                       v4l2_subdev_call(source->sd, video, s_stream, 0);
+
+               max9286_i2c_mux_close(priv);
+       }
+
+       return 0;
+}
+
+static int max9286_enum_mbus_code(struct v4l2_subdev *sd,
+                                 struct v4l2_subdev_pad_config *cfg,
+                                 struct v4l2_subdev_mbus_code_enum *code)
+{
+       if (code->pad || code->index > 0)
+               return -EINVAL;
+
+       code->code = MEDIA_BUS_FMT_UYVY8_1X16;
+
+       return 0;
+}
+
+static struct v4l2_mbus_framefmt *
+max9286_get_pad_format(struct max9286_priv *priv,
+                      struct v4l2_subdev_pad_config *cfg,
+                      unsigned int pad, u32 which)
+{
+       switch (which) {
+       case V4L2_SUBDEV_FORMAT_TRY:
+               return v4l2_subdev_get_try_format(&priv->sd, cfg, pad);
+       case V4L2_SUBDEV_FORMAT_ACTIVE:
+               return &priv->fmt[pad];
+       default:
+               return NULL;
+       }
+}
+
+static int max9286_set_fmt(struct v4l2_subdev *sd,
+                          struct v4l2_subdev_pad_config *cfg,
+                          struct v4l2_subdev_format *format)
+{
+       struct max9286_priv *priv = sd_to_max9286(sd);
+       struct v4l2_mbus_framefmt *cfg_fmt;
+
+       if (format->pad == MAX9286_SRC_PAD)
+               return -EINVAL;
+
+       /* Refuse non YUV422 formats as we hardcode DT to 8 bit YUV422 */
+       switch (format->format.code) {
+       case MEDIA_BUS_FMT_UYVY8_1X16:
+       case MEDIA_BUS_FMT_VYUY8_1X16:
+       case MEDIA_BUS_FMT_YUYV8_1X16:
+       case MEDIA_BUS_FMT_YVYU8_1X16:
+               break;
+       default:
+               format->format.code = MEDIA_BUS_FMT_UYVY8_1X16;
+               break;
+       }
+
+       cfg_fmt = max9286_get_pad_format(priv, cfg, format->pad, format->which);
+       if (!cfg_fmt)
+               return -EINVAL;
+
+       mutex_lock(&priv->mutex);
+       *cfg_fmt = format->format;
+       mutex_unlock(&priv->mutex);
+
+       return 0;
+}
+
+static int max9286_get_fmt(struct v4l2_subdev *sd,
+                          struct v4l2_subdev_pad_config *cfg,
+                          struct v4l2_subdev_format *format)
+{
+       struct max9286_priv *priv = sd_to_max9286(sd);
+       struct v4l2_mbus_framefmt *cfg_fmt;
+       unsigned int pad = format->pad;
+
+       /*
+        * Multiplexed Stream Support: Support link validation by returning the
+        * format of the first bound link. All links must have the same format,
+        * as we do not support mixing and matching of cameras connected to the
+        * max9286.
+        */
+       if (pad == MAX9286_SRC_PAD)
+               pad = __ffs(priv->bound_sources);
+
+       cfg_fmt = max9286_get_pad_format(priv, cfg, pad, format->which);
+       if (!cfg_fmt)
+               return -EINVAL;
+
+       mutex_lock(&priv->mutex);
+       format->format = *cfg_fmt;
+       mutex_unlock(&priv->mutex);
+
+       return 0;
+}
+
+static const struct v4l2_subdev_video_ops max9286_video_ops = {
+       .s_stream       = max9286_s_stream,
+};
+
+static const struct v4l2_subdev_pad_ops max9286_pad_ops = {
+       .enum_mbus_code = max9286_enum_mbus_code,
+       .get_fmt        = max9286_get_fmt,
+       .set_fmt        = max9286_set_fmt,
+};
+
+static const struct v4l2_subdev_ops max9286_subdev_ops = {
+       .video          = &max9286_video_ops,
+       .pad            = &max9286_pad_ops,
+};
+
+static void max9286_init_format(struct v4l2_mbus_framefmt *fmt)
+{
+       fmt->width              = 1280;
+       fmt->height             = 800;
+       fmt->code               = MEDIA_BUS_FMT_UYVY8_1X16;
+       fmt->colorspace         = V4L2_COLORSPACE_SRGB;
+       fmt->field              = V4L2_FIELD_NONE;
+       fmt->ycbcr_enc          = V4L2_YCBCR_ENC_DEFAULT;
+       fmt->quantization       = V4L2_QUANTIZATION_DEFAULT;
+       fmt->xfer_func          = V4L2_XFER_FUNC_DEFAULT;
+}
+
+static int max9286_open(struct v4l2_subdev *subdev, struct v4l2_subdev_fh *fh)
+{
+       struct v4l2_mbus_framefmt *format;
+       unsigned int i;
+
+       for (i = 0; i < MAX9286_N_SINKS; i++) {
+               format = v4l2_subdev_get_try_format(subdev, fh->pad, i);
+               max9286_init_format(format);
+       }
+
+       return 0;
+}
+
+static const struct v4l2_subdev_internal_ops max9286_subdev_internal_ops = {
+       .open = max9286_open,
+};
+
+static int max9286_s_ctrl(struct v4l2_ctrl *ctrl)
+{
+       switch (ctrl->id) {
+       case V4L2_CID_PIXEL_RATE:
+               return 0;
+       default:
+               return -EINVAL;
+       }
+}
+
+static const struct v4l2_ctrl_ops max9286_ctrl_ops = {
+       .s_ctrl = max9286_s_ctrl,
+};
+
+static int max9286_v4l2_register(struct max9286_priv *priv)
+{
+       struct device *dev = &priv->client->dev;
+       struct fwnode_handle *ep;
+       int ret;
+       int i;
+
+       /* Register v4l2 async notifiers for connected Camera subdevices */
+       ret = max9286_v4l2_notifier_register(priv);
+       if (ret) {
+               dev_err(dev, "Unable to register V4L2 async notifiers\n");
+               return ret;
+       }
+
+       /* Configure V4L2 for the MAX9286 itself */
+
+       for (i = 0; i < MAX9286_N_SINKS; i++)
+               max9286_init_format(&priv->fmt[i]);
+
+       v4l2_i2c_subdev_init(&priv->sd, priv->client, &max9286_subdev_ops);
+       priv->sd.internal_ops = &max9286_subdev_internal_ops;
+       priv->sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
+
+       v4l2_ctrl_handler_init(&priv->ctrls, 1);
+       priv->pixelrate = v4l2_ctrl_new_std(&priv->ctrls,
+                                           &max9286_ctrl_ops,
+                                           V4L2_CID_PIXEL_RATE,
+                                           1, INT_MAX, 1, 50000000);
+
+       priv->sd.ctrl_handler = &priv->ctrls;
+       ret = priv->ctrls.error;
+       if (ret)
+               goto err_async;
+
+       priv->sd.entity.function = MEDIA_ENT_F_VID_IF_BRIDGE;
+
+       priv->pads[MAX9286_SRC_PAD].flags = MEDIA_PAD_FL_SOURCE;
+       for (i = 0; i < MAX9286_SRC_PAD; i++)
+               priv->pads[i].flags = MEDIA_PAD_FL_SINK;
+       ret = media_entity_pads_init(&priv->sd.entity, MAX9286_N_PADS,
+                                    priv->pads);
+       if (ret)
+               goto err_async;
+
+       ep = fwnode_graph_get_endpoint_by_id(dev_fwnode(dev), MAX9286_SRC_PAD,
+                                            0, 0);
+       if (!ep) {
+               dev_err(dev, "Unable to retrieve endpoint on \"port@4\"\n");
+               ret = -ENOENT;
+               goto err_async;
+       }
+       priv->sd.fwnode = ep;
+
+       ret = v4l2_async_register_subdev(&priv->sd);
+       if (ret < 0) {
+               dev_err(dev, "Unable to register subdevice\n");
+               goto err_put_node;
+       }
+
+       return 0;
+
+err_put_node:
+       fwnode_handle_put(ep);
+err_async:
+       max9286_v4l2_notifier_unregister(priv);
+
+       return ret;
+}
+
+static void max9286_v4l2_unregister(struct max9286_priv *priv)
+{
+       fwnode_handle_put(priv->sd.fwnode);
+       v4l2_async_unregister_subdev(&priv->sd);
+       max9286_v4l2_notifier_unregister(priv);
+}
+
+/* 
-----------------------------------------------------------------------------
+ * Probe/Remove
+ */
+
+static int max9286_setup(struct max9286_priv *priv)
+{
+       /*
+        * Link ordering values for all enabled links combinations. Orders must
+        * be assigned sequentially from 0 to the number of enabled links
+        * without leaving any hole for disabled links. We thus assign orders to
+        * enabled links first, and use the remaining order values for disabled
+        * links are all links must have a different order value;
+        */
+       static const u8 link_order[] = {
+               (3 << 6) | (2 << 4) | (1 << 2) | (0 << 0), /* xxxx */
+               (3 << 6) | (2 << 4) | (1 << 2) | (0 << 0), /* xxx0 */
+               (3 << 6) | (2 << 4) | (0 << 2) | (1 << 0), /* xx0x */
+               (3 << 6) | (2 << 4) | (1 << 2) | (0 << 0), /* xx10 */
+               (3 << 6) | (0 << 4) | (2 << 2) | (1 << 0), /* x0xx */
+               (3 << 6) | (1 << 4) | (2 << 2) | (0 << 0), /* x1x0 */
+               (3 << 6) | (1 << 4) | (0 << 2) | (2 << 0), /* x10x */
+               (3 << 6) | (1 << 4) | (1 << 2) | (0 << 0), /* x210 */
+               (0 << 6) | (3 << 4) | (2 << 2) | (1 << 0), /* 0xxx */
+               (1 << 6) | (3 << 4) | (2 << 2) | (0 << 0), /* 1xx0 */
+               (1 << 6) | (3 << 4) | (0 << 2) | (2 << 0), /* 1x0x */
+               (2 << 6) | (3 << 4) | (1 << 2) | (0 << 0), /* 2x10 */
+               (1 << 6) | (0 << 4) | (3 << 2) | (2 << 0), /* 10xx */
+               (2 << 6) | (1 << 4) | (3 << 2) | (0 << 0), /* 21x0 */
+               (2 << 6) | (1 << 4) | (0 << 2) | (3 << 0), /* 210x */
+               (3 << 6) | (2 << 4) | (1 << 2) | (0 << 0), /* 3210 */
+       };
+
+       /*
+        * Set the I2C bus speed.
+        *
+        * Enable I2C Local Acknowledge during the probe sequences of the camera
+        * only. This should be disabled after the mux is initialised.
+        */
+       max9286_configure_i2c(priv, true);
+
+       /*
+        * Reverse channel setup.
+        *
+        * - Enable custom reverse channel configuration (through register 0x3f)
+        *   and set the first pulse length to 35 clock cycles.
+        * - Increase the reverse channel amplitude to 170mV to accommodate the
+        *   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);
+       usleep_range(2000, 2500);
+
+       /*
+        * Enable GMSL links, mask unused ones and autodetect link
+        * used as CSI clock source.
+        */
+       max9286_write(priv, 0x00, MAX9286_MSTLINKSEL_AUTO | priv->route_mask);
+       max9286_write(priv, 0x0b, link_order[priv->route_mask]);
+       max9286_write(priv, 0x69, (0xf & ~priv->route_mask));
+
+       /*
+        * Video format setup:
+        * Disable CSI output, VC is set according to Link number.
+        */
+       max9286_write(priv, 0x15, MAX9286_VCTYPE | MAX9286_0X15_RESV);
+
+       /* Enable CSI-2 Lane D0-D3 only, DBL mode, YUV422 8-bit. */
+       max9286_write(priv, 0x12, MAX9286_CSIDBL | MAX9286_DBL |
+                     MAX9286_CSILANECNT(priv->csi2_data_lanes) |
+                     MAX9286_DATATYPE_YUV422_8BIT);
+
+       /* Automatic: FRAMESYNC taken from the slowest Link. */
+       max9286_write(priv, 0x01, MAX9286_FSYNCMODE_INT_HIZ |
+                     MAX9286_FSYNCMETH_AUTO);
+
+       /* Enable HS/VS encoding, use D14/15 for HS/VS, invert VS. */
+       max9286_write(priv, 0x0c, MAX9286_HVEN | MAX9286_INVVS |
+                     MAX9286_HVSRC_D14);
+
+       /*
+        * The overlap window seems to provide additional validation by tracking
+        * the delay between vsync and frame sync, generating an error if the
+        * delay is bigger than the programmed window, though it's not yet clear
+        * what value should be set.
+        *
+        * As it's an optional value and can be disabled, we do so by setting
+        * a 0 overlap value.
+        */
+       max9286_write(priv, 0x63, 0);
+       max9286_write(priv, 0x64, 0);
+
+       /*
+        * Wait for 2ms to allow the link to resynchronize after the
+        * configuration change.
+        */
+       usleep_range(2000, 5000);
+
+       return 0;
+}
+
+static void max9286_gpio_set(struct gpio_chip *chip,
+                            unsigned int offset, int value)
+{
+       struct max9286_priv *priv = gpiochip_get_data(chip);
+
+       if (value)
+               priv->gpio_state |= BIT(offset);
+       else
+               priv->gpio_state &= ~BIT(offset);
+
+       max9286_write(priv, 0x0f, MAX9286_0X0F_RESERVED | priv->gpio_state);
+}
+
+static int max9286_gpio_get(struct gpio_chip *chip, unsigned int offset)
+{
+       struct max9286_priv *priv = gpiochip_get_data(chip);
+
+       return priv->gpio_state & BIT(offset);
+}
+
+static int max9286_register_gpio(struct max9286_priv *priv)
+{
+       struct device *dev = &priv->client->dev;
+       struct gpio_chip *gpio = &priv->gpio;
+       int ret;
+
+       /* Configure the GPIO */
+       gpio->label = dev_name(dev);
+       gpio->parent = dev;
+       gpio->owner = THIS_MODULE;
+       gpio->of_node = dev->of_node;
+       gpio->ngpio = 2;
+       gpio->base = -1;
+       gpio->set = max9286_gpio_set;
+       gpio->get = max9286_gpio_get;
+       gpio->can_sleep = true;
+
+       /* GPIO values default to high */
+       priv->gpio_state = BIT(0) | BIT(1);
+
+       ret = devm_gpiochip_add_data(dev, gpio, priv);
+       if (ret)
+               dev_err(dev, "Unable to create gpio_chip\n");
+
+       return ret;
+}
+
+static int max9286_init(struct device *dev)
+{
+       struct max9286_priv *priv;
+       struct i2c_client *client;
+       int ret;
+
+       client = to_i2c_client(dev);
+       priv = i2c_get_clientdata(client);
+
+       /* Enable the bus power. */
+       ret = regulator_enable(priv->regulator);
+       if (ret < 0) {
+               dev_err(&client->dev, "Unable to turn PoC on\n");
+               return ret;
+       }
+
+       ret = max9286_setup(priv);
+       if (ret) {
+               dev_err(dev, "Unable to setup max9286\n");
+               goto err_regulator;
+       }
+
+       /*
+        * Register all V4L2 interactions for the MAX9286 and notifiers for
+        * any subdevices connected.
+        */
+       ret = max9286_v4l2_register(priv);
+       if (ret) {
+               dev_err(dev, "Failed to register with V4L2\n");
+               goto err_regulator;
+       }
+
+       ret = max9286_i2c_mux_init(priv);
+       if (ret) {
+               dev_err(dev, "Unable to initialize I2C multiplexer\n");
+               goto err_v4l2_register;
+       }
+
+       /* Leave the mux channels disabled until they are selected. */
+       max9286_i2c_mux_close(priv);
+
+       return 0;
+
+err_v4l2_register:
+       max9286_v4l2_unregister(priv);
+err_regulator:
+       regulator_disable(priv->regulator);
+
+       return ret;
+}
+
+static void max9286_cleanup_dt(struct max9286_priv *priv)
+{
+       struct max9286_source *source;
+
+       for_each_source(priv, source) {
+               fwnode_handle_put(source->fwnode);
+               source->fwnode = NULL;
+       }
+}
+
+static int max9286_parse_dt(struct max9286_priv *priv)
+{
+       struct device *dev = &priv->client->dev;
+       struct device_node *i2c_mux;
+       struct device_node *node = NULL;
+       unsigned int i2c_mux_mask = 0;
+
+       /* Balance the of_node_put() performed by of_find_node_by_name(). */
+       of_node_get(dev->of_node);
+       i2c_mux = of_find_node_by_name(dev->of_node, "i2c-mux");
+       if (!i2c_mux) {
+               dev_err(dev, "Failed to find i2c-mux node\n");
+               return -EINVAL;
+       }
+
+       /* Identify which i2c-mux channels are enabled */
+       for_each_child_of_node(i2c_mux, node) {
+               u32 id = 0;
+
+               of_property_read_u32(node, "reg", &id);
+               if (id >= MAX9286_NUM_GMSL)
+                       continue;
+
+               if (!of_device_is_available(node)) {
+                       dev_dbg(dev, "Skipping disabled I2C bus port %u\n", id);
+                       continue;
+               }
+
+               i2c_mux_mask |= BIT(id);
+       }
+       of_node_put(node);
+       of_node_put(i2c_mux);
+
+       /* Parse the endpoints */
+       for_each_endpoint_of_node(dev->of_node, node) {
+               struct max9286_source *source;
+               struct of_endpoint ep;
+
+               of_graph_parse_endpoint(node, &ep);
+               dev_dbg(dev, "Endpoint %pOF on port %d",
+                       ep.local_node, ep.port);
+
+               if (ep.port > MAX9286_NUM_GMSL) {
+                       dev_err(dev, "Invalid endpoint %s on port %d",
+                               of_node_full_name(ep.local_node), ep.port);
+                       continue;
+               }
+
+               /* For the source endpoint just parse the bus configuration. */
+               if (ep.port == MAX9286_SRC_PAD) {
+                       struct v4l2_fwnode_endpoint vep = {
+                               .bus_type = V4L2_MBUS_CSI2_DPHY
+                       };
+                       int ret;
+
+                       ret = v4l2_fwnode_endpoint_parse(
+                                       of_fwnode_handle(node), &vep);
+                       if (ret) {
+                               of_node_put(node);
+                               return ret;
+                       }
+
+                       priv->csi2_data_lanes =
+                               vep.bus.mipi_csi2.num_data_lanes;
+
+                       continue;
+               }
+
+               /* Skip if the corresponding GMSL link is unavailable. */
+               if (!(i2c_mux_mask & BIT(ep.port)))
+                       continue;
+
+               if (priv->sources[ep.port].fwnode) {
+                       dev_err(dev,
+                               "Multiple port endpoints are not supported: %d",
+                               ep.port);
+
+                       continue;
+               }
+
+               source = &priv->sources[ep.port];
+               source->fwnode = fwnode_graph_get_remote_endpoint(
+                                               of_fwnode_handle(node));
+               if (!source->fwnode) {
+                       dev_err(dev,
+                               "Endpoint %pOF has no remote endpoint 
connection\n",
+                               ep.local_node);
+
+                       continue;
+               }
+
+               priv->source_mask |= BIT(ep.port);
+               priv->nsources++;
+       }
+       of_node_put(node);
+
+       priv->route_mask = priv->source_mask;
+
+       return 0;
+}
+
+static int max9286_probe(struct i2c_client *client)
+{
+       struct max9286_priv *priv;
+       int ret;
+
+       priv = devm_kzalloc(&client->dev, sizeof(*priv), GFP_KERNEL);
+       if (!priv)
+               return -ENOMEM;
+
+       mutex_init(&priv->mutex);
+
+       priv->client = client;
+       i2c_set_clientdata(client, priv);
+
+       priv->gpiod_pwdn = devm_gpiod_get_optional(&client->dev, "enable",
+                                                  GPIOD_OUT_HIGH);
+       if (IS_ERR(priv->gpiod_pwdn))
+               return PTR_ERR(priv->gpiod_pwdn);
+
+       gpiod_set_consumer_name(priv->gpiod_pwdn, "max9286-pwdn");
+       gpiod_set_value_cansleep(priv->gpiod_pwdn, 1);
+
+       /* Wait at least 4ms before the I2C lines latch to the address */
+       if (priv->gpiod_pwdn)
+               usleep_range(4000, 5000);
+
+       /*
+        * The MAX9286 starts by default with all ports enabled, we disable all
+        * ports early to ensure that all channels are disabled if we error out
+        * and keep the bus consistent.
+        */
+       max9286_i2c_mux_close(priv);
+
+       /*
+        * The MAX9286 initialises with auto-acknowledge enabled by default.
+        * This can be invasive to other transactions on the same bus, so
+        * disable it early. It will be enabled only as and when needed.
+        */
+       max9286_configure_i2c(priv, false);
+
+       ret = max9286_register_gpio(priv);
+       if (ret)
+               goto err_powerdown;
+
+       priv->regulator = devm_regulator_get(&client->dev, "poc");
+       if (IS_ERR(priv->regulator)) {
+               if (PTR_ERR(priv->regulator) != -EPROBE_DEFER)
+                       dev_err(&client->dev,
+                               "Unable to get PoC regulator (%ld)\n",
+                               PTR_ERR(priv->regulator));
+               ret = PTR_ERR(priv->regulator);
+               goto err_powerdown;
+       }
+
+       ret = max9286_parse_dt(priv);
+       if (ret)
+               goto err_powerdown;
+
+       ret = max9286_init(&client->dev);
+       if (ret < 0)
+               goto err_cleanup_dt;
+
+       return 0;
+
+err_cleanup_dt:
+       max9286_cleanup_dt(priv);
+err_powerdown:
+       gpiod_set_value_cansleep(priv->gpiod_pwdn, 0);
+
+       return ret;
+}
+
+static int max9286_remove(struct i2c_client *client)
+{
+       struct max9286_priv *priv = i2c_get_clientdata(client);
+
+       i2c_mux_del_adapters(priv->mux);
+
+       max9286_v4l2_unregister(priv);
+
+       regulator_disable(priv->regulator);
+
+       gpiod_set_value_cansleep(priv->gpiod_pwdn, 0);
+
+       max9286_cleanup_dt(priv);
+
+       return 0;
+}
+
+static const struct of_device_id max9286_dt_ids[] = {
+       { .compatible = "maxim,max9286" },
+       {},
+};
+MODULE_DEVICE_TABLE(of, max9286_dt_ids);
+
+static struct i2c_driver max9286_i2c_driver = {
+       .driver = {
+               .name           = "max9286",
+               .of_match_table = of_match_ptr(max9286_dt_ids),
+       },
+       .probe_new      = max9286_probe,
+       .remove         = max9286_remove,
+};
+
+module_i2c_driver(max9286_i2c_driver);
+
+MODULE_DESCRIPTION("Maxim MAX9286 GMSL Deserializer Driver");
+MODULE_AUTHOR("Jacopo Mondi, Kieran Bingham, Laurent Pinchart, Niklas 
Söderlund, Vladimir Barinov");
+MODULE_LICENSE("GPL");
-- 
2.25.1

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