Hi Niklas,

This should be at least v5.

Did you take the last v4 and work from there?
I have made changes since the last posting. Did you get an update from
my branches?

What changes have you made to this posting compared to whichever
patch-base you have taken to start from?

--
Kieran



On 09/08/2019 05:05, Niklas Söderlund wrote:
> 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. The
> driver however limits the number of cameras to one as there are no way
> to express in V4L2 today that multiple video streams are transmitted
> over one CSI-2 bus.
> 
> 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>
> ---
>  MAINTAINERS                 |   10 +
>  drivers/media/i2c/Kconfig   |   11 +
>  drivers/media/i2c/Makefile  |    1 +
>  drivers/media/i2c/max9286.c | 1081 +++++++++++++++++++++++++++++++++++
>  4 files changed, 1103 insertions(+)
>  create mode 100644 drivers/media/i2c/max9286.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 6426db5198f05377..f8f028811feee489 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -9746,6 +9746,16 @@ F:     
> Documentation/devicetree/bindings/hwmon/max6697.txt
>  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-media@vger.kernel.org
> +S:   Maintained
> +F:   Documentation/devicetree/bindings/media/i2c/maxim,max9286.txt
> +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 79ce9ec6fc1be1e6..c20b151a16e64349 100644
> --- a/drivers/media/i2c/Kconfig
> +++ b/drivers/media/i2c/Kconfig
> @@ -439,6 +439,17 @@ 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 VIDEO_V4L2_SUBDEV_API && MEDIA_CONTROLLER
> +     select V4L2_FWNODE
> +     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 fd4ea86dedd5df44..25b3c7e5becfa714 100644
> --- a/drivers/media/i2c/Makefile
> +++ b/drivers/media/i2c/Makefile
> @@ -114,5 +114,6 @@ obj-$(CONFIG_VIDEO_IMX274)        += imx274.o
>  obj-$(CONFIG_VIDEO_IMX319)   += imx319.o
>  obj-$(CONFIG_VIDEO_IMX355)   += imx355.o
>  obj-$(CONFIG_VIDEO_ST_MIPID02) += st-mipid02.o
> +obj-$(CONFIG_VIDEO_MAX9286)  += max9286.o
>  
>  obj-$(CONFIG_SDR_MAX2175) += max2175.o
> diff --git a/drivers/media/i2c/max9286.c b/drivers/media/i2c/max9286.c
> new file mode 100644
> index 0000000000000000..debd11ac269d28ca
> --- /dev/null
> +++ b/drivers/media/i2c/max9286.c
> @@ -0,0 +1,1081 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Maxim MAX9286 GMSL Deserializer Driver
> + *
> + * Copyright (C) 2017-2018 Jacopo Mondi
> + * Copyright (C) 2017-2018 Kieran Bingham
> + * Copyright (C) 2017-2018 Laurent Pinchart
> + * Copyright (C) 2017-2018 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/i2c.h>
> +#include <linux/i2c-mux.h>
> +#include <linux/module.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 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)
> +
> +#define MAX9286_NUM_GMSL             4
> +#define MAX9286_N_SINKS                      4
> +#define MAX9286_N_PADS                       5
> +#define MAX9286_SRC_PAD                      4
> +
> +#define MAXIM_I2C_I2C_SPEED_400KHZ   MAX9286_I2CMSTBT_339KBPS
> +#define MAXIM_I2C_I2C_SPEED_100KHZ   MAX9286_I2CMSTBT_105KBPS
> +#define MAXIM_I2C_SPEED                      MAXIM_I2C_I2C_SPEED_100KHZ
> +
> +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 v4l2_subdev sd;
> +     struct media_pad pads[MAX9286_N_PADS];
> +     struct regulator *regulator;
> +     bool poc_enabled;
> +     int streaming;
> +
> +     struct i2c_mux_core *mux;
> +     unsigned int mux_channel;
> +
> +     struct v4l2_ctrl_handler ctrls;
> +
> +     struct v4l2_mbus_framefmt fmt[MAX9286_N_SINKS];
> +
> +     unsigned int nsources;
> +     unsigned int source_mask;
> +     unsigned int route_mask;
> +     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(max9286, source) \
> +     for (source = NULL; (source = next_source(max9286, source)); )
> +
> +#define to_index(max9286, source) (source - &max9286->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 int max9286_i2c_mux_close(struct max9286_priv *priv)
> +{
> +     /* FIXME: See note in max9286_i2c_mux_select() */
> +     if (priv->streaming)
> +             return 0;
> +     /*
> +      * 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 select call.
> +      */
> +     priv->mux_channel = -1;
> +     max9286_write(priv, 0x0a, 0x00);
> +     usleep_range(3000, 5000);
> +
> +     return 0;
> +}
> +
> +static int max9286_i2c_mux_select(struct i2c_mux_core *muxc, u32 chan)
> +{
> +     struct max9286_priv *priv = i2c_mux_priv(muxc);
> +
> +     /*
> +      * FIXME: This state keeping is a hack and do the job. It should
> +      * be should be reworked. One option to consider is that once all
> +      * cameras are programmed the mux selection logic should be disabled
> +      * and all all reverse and forward channels enable all the time.
> +      *
> +      * In any case this logic with a int that have two states should be
> +      * reworked!
> +      */
> +     if (priv->streaming == 1) {
> +             max9286_write(priv, 0x0a, 0xff);
> +             priv->streaming = 2;
> +             return 0;
> +     } else if (priv->streaming == 2) {
> +             return 0;
> +     }
> +
> +     if (priv->mux_channel == chan)
> +             return 0;
> +
> +     priv->mux_channel = chan;
> +
> +     max9286_write(priv, 0x0a,
> +                   MAX9286_FWDCCEN(chan) | MAX9286_REVCCEN(chan));
> +
> +     /*
> +      * We must sleep after any change to the forward or reverse channel
> +      * configuration.
> +      */
> +     usleep_range(3000, 5000);
> +
> +     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 |
> +                 MAXIM_I2C_SPEED;
> +
> +     if (localack)
> +             config |= MAX9286_I2CLOCACK;
> +
> +     max9286_write(priv, 0x34, config);
> +     usleep_range(3000, 5000);
> +}
> +
> +/* 
> -----------------------------------------------------------------------------
> + * V4L2 Subdev
> + */
> +
> +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;
> +     }
> +
> +     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);
> +
> +     return 0;
> +}
> +
> +static void max9286_notify_unbind(struct v4l2_async_notifier *notifier,
> +                               struct v4l2_subdev *subdev,
> +                               struct v4l2_async_subdev *asd)
> +{
> +     struct max9286_source *source = asd_to_max9286_source(asd);
> +
> +     source->sd = NULL;
> +}
> +
> +static const struct v4l2_async_notifier_operations max9286_notify_ops = {
> +     .bound = max9286_notify_bound,
> +     .unbind = max9286_notify_unbind,
> +};
> +
> +/*
> + * 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;
> +}
> +
> +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) {
> +             /* FIXME: See note in max9286_i2c_mux_select() */
> +             priv->streaming = 1;
> +
> +             /* 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 pratical experience at least 8 are required. Give
> +              * 12 complete frames time (~33ms at 30 fps) to achieve frame
> +              * locking before returning error.
> +              */
> +             for (i = 0; i < 36; 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 -EINVAL;
> +             }
> +
> +             /*
> +              * 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);
> +
> +             /* FIXME: See note in max9286_i2c_mux_select() */
> +             priv->streaming = 0;
> +     }
> +
> +     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_2X8;
> +
> +     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_2X8:
> +     case MEDIA_BUS_FMT_VYUY8_2X8:
> +     case MEDIA_BUS_FMT_YUYV8_2X8:
> +     case MEDIA_BUS_FMT_YVYU8_2X8:
> +             break;
> +     default:
> +             format->format.code = MEDIA_BUS_FMT_YUYV8_2X8;
> +             break;
> +     }
> +
> +     cfg_fmt = max9286_get_pad_format(priv, cfg, format->pad, format->which);
> +     if (!cfg_fmt)
> +             return -EINVAL;
> +
> +     *cfg_fmt = format->format;
> +
> +     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;
> +
> +     if (format->pad >= MAX9286_SRC_PAD)
> +             return -EINVAL;
> +
> +     cfg_fmt = max9286_get_pad_format(priv, cfg, format->pad, format->which);
> +     if (!cfg_fmt)
> +             return -EINVAL;
> +
> +     format->format = *cfg_fmt;
> +
> +     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_2X8;
> +     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,
> +};
> +
> +/* 
> -----------------------------------------------------------------------------
> + * 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);
> +
> +     /*
> +      * 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 accordingly 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);
> +
> +     /*
> +      * Wait for 2ms to allow the link to resynchronize after the
> +      * configuration change.
> +      */
> +     usleep_range(2000, 5000);
> +
> +     return 0;
> +}
> +
> +static const struct of_device_id max9286_dt_ids[] = {
> +     { .compatible = "maxim,max9286" },
> +     {},
> +};
> +MODULE_DEVICE_TABLE(of, max9286_dt_ids);
> +
> +static int max9286_init(struct device *dev)
> +{
> +     struct max9286_priv *priv;
> +     struct i2c_client *client;
> +     struct fwnode_handle *ep;
> +     unsigned int i;
> +     int ret;
> +
> +     /* Skip non-max9286 devices. */
> +     if (!dev->of_node || !of_match_node(max9286_dt_ids, dev->of_node))
> +             return 0;
> +
> +     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;
> +     }
> +
> +     priv->poc_enabled = true;
> +
> +     ret = max9286_setup(priv);
> +     if (ret) {
> +             dev_err(dev, "Unable to setup max9286\n");
> +             goto err_regulator;
> +     }
> +
> +     v4l2_i2c_subdev_init(&priv->sd, 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);
> +     /*
> +      * FIXME: Compute the real pixel rate. The 50 MP/s value comes from the
> +      * hardcoded frequency in the BSP CSI-2 receiver driver.
> +      */
> +     v4l2_ctrl_new_std(&priv->ctrls, NULL, V4L2_CID_PIXEL_RATE,
> +                       50000000, 50000000, 1, 50000000);
> +     priv->sd.ctrl_handler = &priv->ctrls;
> +     ret = priv->ctrls.error;
> +     if (ret)
> +             goto err_regulator;
> +
> +     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_regulator;
> +
> +     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_regulator;
> +     }
> +     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;
> +     }
> +
> +     ret = max9286_i2c_mux_init(priv);
> +     if (ret) {
> +             dev_err(dev, "Unable to initialize I2C multiplexer\n");
> +             goto err_subdev_unregister;
> +     }
> +
> +     /*
> +      * Re-configure I2C with local acknowledge disabled after cameras
> +      * have probed.
> +      */
> +     max9286_configure_i2c(priv, false);
> +
> +     /* Leave the mux channels disabled until they are selected. */
> +     max9286_i2c_mux_close(priv);
> +
> +     return 0;
> +
> +err_subdev_unregister:
> +     v4l2_async_unregister_subdev(&priv->sd);
> +     max9286_i2c_mux_close(priv);
> +err_put_node:
> +     fwnode_handle_put(ep);
> +err_regulator:
> +     regulator_disable(priv->regulator);
> +     priv->poc_enabled = false;
> +
> +     return ret;
> +}
> +
> +static struct device_node *max9286_get_i2c_by_id(struct device_node *parent,
> +                                              u32 id)
> +{
> +     struct device_node *child;
> +
> +     for_each_child_of_node(parent, child) {
> +             u32 i2c_id = 0;
> +
> +             if (of_node_cmp(child->name, "i2c") != 0)
> +                     continue;
> +             of_property_read_u32(child, "reg", &i2c_id);
> +             if (id == i2c_id)
> +                     return child;
> +     }
> +
> +     return NULL;
> +}
> +
> +static int max9286_check_i2c_bus_by_id(struct device *dev, int id)
> +{
> +     struct device_node *i2c_np;
> +
> +     i2c_np = max9286_get_i2c_by_id(dev->of_node, id);
> +     if (!i2c_np) {
> +             dev_err(dev, "Failed to find corresponding i2c@%u\n", id);
> +             return -ENODEV;
> +     }
> +
> +     if (!of_device_is_available(i2c_np)) {
> +             dev_dbg(dev, "Skipping port %u with disabled I2C bus\n", id);
> +             of_node_put(i2c_np);
> +             return -ENODEV;
> +     }
> +
> +     of_node_put(i2c_np);
> +
> +     return 0;
> +}
> +
> +static void max9286_cleanup_dt(struct max9286_priv *priv)
> +{
> +     struct max9286_source *source;
> +
> +     /*
> +      * Not strictly part of the DT, but the notifier is registered during
> +      * max9286_parse_dt(), and the notifier holds references to the fwnodes
> +      * thus the cleanup is here to mirror the registration.
> +      */
> +     v4l2_async_notifier_unregister(&priv->notifier);
> +     v4l2_async_notifier_cleanup(&priv->notifier);
> +
> +     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 *ep_np = NULL;
> +     int ret;
> +
> +     v4l2_async_notifier_init(&priv->notifier);
> +
> +     for_each_endpoint_of_node(dev->of_node, ep_np) {
> +             struct max9286_source *source;
> +             struct of_endpoint ep;
> +
> +             of_graph_parse_endpoint(ep_np, &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 = 0 };
> +                     int ret;
> +
> +                     ret = 
> v4l2_fwnode_endpoint_parse(of_fwnode_handle(ep_np),
> +                                                      &vep);
> +                     if (ret)
> +                             return ret;
> +
> +                     if (vep.bus_type != V4L2_MBUS_CSI2_DPHY) {
> +                             dev_err(dev,
> +                                     "Media bus %u type not supported\n",
> +                                     vep.bus_type);
> +                             v4l2_fwnode_endpoint_free(&vep);
> +                             return -EINVAL;
> +                     }
> +
> +                     priv->csi2_data_lanes =
> +                             vep.bus.mipi_csi2.num_data_lanes;
> +                     v4l2_fwnode_endpoint_free(&vep);
> +
> +                     continue;
> +             }
> +
> +             /* Skip if the corresponding GMSL link is unavailable. */
> +             if (max9286_check_i2c_bus_by_id(dev, 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(ep_np));
> +             if (!source->fwnode) {
> +                     dev_err(dev,
> +                             "Endpoint %pOF has no remote endpoint 
> connection\n",
> +                             ep.local_node);
> +
> +                     continue;
> +             }
> +
> +             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) {
> +                     v4l2_async_notifier_cleanup(&priv->notifier);
> +                     return ret;
> +             }
> +
> +             priv->source_mask |= BIT(ep.port);
> +             priv->nsources++;
> +     }
> +
> +     /* Do not register the subdev notifier if there are no devices. */
> +     if (!priv->nsources)
> +             return 0;
> +
> +     priv->route_mask = priv->source_mask;
> +     priv->notifier.ops = &max9286_notify_ops;
> +
> +     ret = v4l2_async_subdev_notifier_register(&priv->sd, &priv->notifier);
> +     if (ret)
> +             v4l2_async_notifier_cleanup(&priv->notifier);
> +
> +     return 0;
> +}
> +
> +static int max9286_probe(struct i2c_client *client,
> +                      const struct i2c_device_id *did)
> +{
> +     struct max9286_priv *priv;
> +     unsigned int i;
> +     int ret;
> +
> +     priv = kzalloc(sizeof(*priv), GFP_KERNEL);
> +     if (!priv)
> +             return -ENOMEM;
> +
> +     priv->client = client;
> +     i2c_set_clientdata(client, priv);
> +
> +     for (i = 0; i < MAX9286_N_SINKS; i++)
> +             max9286_init_format(&priv->fmt[i]);
> +
> +     ret = max9286_parse_dt(priv);
> +     if (ret)
> +             return ret;
> +
> +     priv->regulator = 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_free;
> +     }
> +
> +     /*
> +      * We can have multiple MAX9286 instances on the same physical I2C
> +      * bus, and I2C children behind ports of separate MAX9286 instances
> +      * having the same I2C address. As the MAX9286 starts by default with
> +      * all ports enabled, we need to disable all ports on all MAX9286
> +      * instances before proceeding to further initialize the devices and
> +      * instantiate children.
> +      *
> +      * Start by just disabling all channels on the current device. Then,
> +      * if all other MAX9286 on the parent bus have been probed, proceed
> +      * to initialize them all, including the current one.
> +      */
> +     max9286_i2c_mux_close(priv);
> +
> +     /*
> +      * The MAX9286 initialises with auto-acknowledge enabled by default.
> +      * This means that if multiple MAX9286 devices are connected to an I2C
> +      * bus, another MAX9286 could ack I2C transfers meant for a device on
> +      * the other side of the GMSL links for this MAX9286 (such as a
> +      * MAX9271). To prevent that disable auto-acknowledge early on; it
> +      * will be enabled later as needed.
> +      */
> +     max9286_configure_i2c(priv, false);
> +
> +     ret = max9286_init(&client->dev);
> +     if (ret < 0)
> +             goto err_regulator;
> +
> +     return 0;
> +
> +err_regulator:
> +     regulator_put(priv->regulator);
> +     max9286_i2c_mux_close(priv);
> +     max9286_configure_i2c(priv, false);
> +err_free:
> +     max9286_cleanup_dt(priv);
> +     kfree(priv);
> +
> +     return ret;
> +}
> +
> +static int max9286_remove(struct i2c_client *client)
> +{
> +     struct max9286_priv *priv = i2c_get_clientdata(client);
> +
> +     i2c_mux_del_adapters(priv->mux);
> +
> +     fwnode_handle_put(priv->sd.fwnode);
> +     v4l2_async_unregister_subdev(&priv->sd);
> +
> +     if (priv->poc_enabled)
> +             regulator_disable(priv->regulator);
> +     regulator_put(priv->regulator);
> +
> +     max9286_cleanup_dt(priv);
> +     kfree(priv);
> +
> +     return 0;
> +}
> +
> +static const struct i2c_device_id max9286_id[] = {
> +     { "max9286", 0 },
> +     { }
> +};
> +MODULE_DEVICE_TABLE(i2c, max9286_id);
> +
> +static struct i2c_driver max9286_i2c_driver = {
> +     .driver = {
> +             .name           = "max9286",
> +             .of_match_table = of_match_ptr(max9286_dt_ids),
> +     },
> +     .probe          = max9286_probe,
> +     .remove         = max9286_remove,
> +     .id_table       = max9286_id,
> +};
> +
> +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");
> 

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