root/drivers/media/i2c/ds90ub913.c
// SPDX-License-Identifier: GPL-2.0
/*
 * Driver for the Texas Instruments DS90UB913 video serializer
 *
 * Based on a driver from Luca Ceresoli <luca@lucaceresoli.net>
 *
 * Copyright (c) 2019 Luca Ceresoli <luca@lucaceresoli.net>
 * Copyright (c) 2023 Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
 */

#include <linux/bitfield.h>
#include <linux/clk-provider.h>
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/gpio/driver.h>
#include <linux/i2c-atr.h>
#include <linux/i2c.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/property.h>
#include <linux/regmap.h>

#include <media/i2c/ds90ub9xx.h>
#include <media/v4l2-fwnode.h>
#include <media/v4l2-mediabus.h>
#include <media/v4l2-subdev.h>

#define UB913_PAD_SINK                  0
#define UB913_PAD_SOURCE                1

/*
 * UB913 has 4 gpios, but gpios 3 and 4 are reserved for external oscillator
 * mode. Thus we only support 2 gpios for now.
 */
#define UB913_NUM_GPIOS                 2

#define UB913_REG_RESET_CTL                     0x01
#define UB913_REG_RESET_CTL_DIGITAL_RESET_1     BIT(1)
#define UB913_REG_RESET_CTL_DIGITAL_RESET_0     BIT(0)

#define UB913_REG_GENERAL_CFG                   0x03
#define UB913_REG_GENERAL_CFG_CRC_ERR_RESET     BIT(5)
#define UB913_REG_GENERAL_CFG_PCLK_RISING       BIT(0)

#define UB913_REG_MODE_SEL                      0x05
#define UB913_REG_MODE_SEL_MODE_OVERRIDE        BIT(5)
#define UB913_REG_MODE_SEL_MODE_UP_TO_DATE      BIT(4)
#define UB913_REG_MODE_SEL_MODE_MASK            GENMASK(3, 0)

#define UB913_REG_CRC_ERRORS_LSB                0x0a
#define UB913_REG_CRC_ERRORS_MSB                0x0b

#define UB913_REG_GENERAL_STATUS                0x0c

#define UB913_REG_GPIO_CFG(n)                   (0x0d + (n))
#define UB913_REG_GPIO_CFG_ENABLE(n)            BIT(0 + (n) * 4)
#define UB913_REG_GPIO_CFG_DIR_INPUT(n)         BIT(1 + (n) * 4)
#define UB913_REG_GPIO_CFG_REMOTE_EN(n)         BIT(2 + (n) * 4)
#define UB913_REG_GPIO_CFG_OUT_VAL(n)           BIT(3 + (n) * 4)
#define UB913_REG_GPIO_CFG_MASK(n)              (0xf << ((n) * 4))

#define UB913_REG_SCL_HIGH_TIME                 0x11
#define UB913_REG_SCL_LOW_TIME                  0x12

#define UB913_REG_PLL_OVR                       0x35

struct ub913_data {
        struct i2c_client       *client;
        struct regmap           *regmap;
        struct clk              *clkin;

        struct gpio_chip        gpio_chip;

        struct v4l2_subdev      sd;
        struct media_pad        pads[2];

        struct v4l2_async_notifier      notifier;

        struct v4l2_subdev      *source_sd;
        u16                     source_sd_pad;

        u64                     enabled_source_streams;

        struct clk_hw           *clkout_clk_hw;

        struct ds90ub9xx_platform_data *plat_data;

        bool                    pclk_polarity_rising;
};

static inline struct ub913_data *sd_to_ub913(struct v4l2_subdev *sd)
{
        return container_of(sd, struct ub913_data, sd);
}

struct ub913_format_info {
        u32 incode;
        u32 outcode;
};

static const struct ub913_format_info ub913_formats[] = {
        /* Only RAW10 with 8-bit payload is supported at the moment */
        { .incode = MEDIA_BUS_FMT_YUYV8_2X8, .outcode = MEDIA_BUS_FMT_YUYV8_1X16 },
        { .incode = MEDIA_BUS_FMT_UYVY8_2X8, .outcode = MEDIA_BUS_FMT_UYVY8_1X16 },
        { .incode = MEDIA_BUS_FMT_VYUY8_2X8, .outcode = MEDIA_BUS_FMT_VYUY8_1X16 },
        { .incode = MEDIA_BUS_FMT_YVYU8_2X8, .outcode = MEDIA_BUS_FMT_YVYU8_1X16 },
};

static const struct ub913_format_info *ub913_find_format(u32 incode)
{
        unsigned int i;

        for (i = 0; i < ARRAY_SIZE(ub913_formats); i++) {
                if (ub913_formats[i].incode == incode)
                        return &ub913_formats[i];
        }

        return NULL;
}

static int ub913_read(const struct ub913_data *priv, u8 reg, u8 *val,
                      int *err)
{
        unsigned int v;
        int ret;

        if (err && *err)
                return *err;

        ret = regmap_read(priv->regmap, reg, &v);
        if (ret) {
                dev_err(&priv->client->dev,
                        "Cannot read register 0x%02x: %d!\n", reg, ret);
                goto out;
        }

        *val = v;

out:
        if (ret && err)
                *err = ret;

        return ret;
}

static int ub913_write(const struct ub913_data *priv, u8 reg, u8 val,
                       int *err)
{
        int ret;

        if (err && *err)
                return *err;

        ret = regmap_write(priv->regmap, reg, val);
        if (ret < 0)
                dev_err(&priv->client->dev,
                        "Cannot write register 0x%02x: %d!\n", reg, ret);

        if (ret && err)
                *err = ret;

        return ret;
}

static int ub913_update_bits(const struct ub913_data *priv, u8 reg, u8 mask,
                             u8 val, int *err)
{
        int ret;

        if (err && *err)
                return *err;

        ret = regmap_update_bits(priv->regmap, reg, mask, val);
        if (ret < 0)
                dev_err(&priv->client->dev,
                        "Cannot update register 0x%02x %d!\n", reg, ret);

        if (ret && err)
                *err = ret;

        return ret;
}

/*
 * GPIO chip
 */
static int ub913_gpio_get_direction(struct gpio_chip *gc, unsigned int offset)
{
        return GPIO_LINE_DIRECTION_OUT;
}

static int ub913_gpio_direction_out(struct gpio_chip *gc, unsigned int offset,
                                    int value)
{
        struct ub913_data *priv = gpiochip_get_data(gc);
        unsigned int reg_idx = offset / 2;
        unsigned int field_idx = offset % 2;

        return regmap_update_bits(priv->regmap, UB913_REG_GPIO_CFG(reg_idx),
                                  UB913_REG_GPIO_CFG_MASK(field_idx),
                                  UB913_REG_GPIO_CFG_ENABLE(field_idx) |
                                          (value ? UB913_REG_GPIO_CFG_OUT_VAL(field_idx) :
                                                   0));
}

static int ub913_gpio_set(struct gpio_chip *gc, unsigned int offset, int value)
{
        return ub913_gpio_direction_out(gc, offset, value);
}

static int ub913_gpio_of_xlate(struct gpio_chip *gc,
                               const struct of_phandle_args *gpiospec,
                               u32 *flags)
{
        if (flags)
                *flags = gpiospec->args[1];

        return gpiospec->args[0];
}

static int ub913_gpiochip_probe(struct ub913_data *priv)
{
        struct device *dev = &priv->client->dev;
        struct gpio_chip *gc = &priv->gpio_chip;
        int ret;

        /* Initialize GPIOs 0 and 1 to local control, tri-state */
        ub913_write(priv, UB913_REG_GPIO_CFG(0), 0, NULL);

        gc->label = dev_name(dev);
        gc->parent = dev;
        gc->owner = THIS_MODULE;
        gc->base = -1;
        gc->can_sleep = true;
        gc->ngpio = UB913_NUM_GPIOS;
        gc->get_direction = ub913_gpio_get_direction;
        gc->direction_output = ub913_gpio_direction_out;
        gc->set = ub913_gpio_set;
        gc->of_xlate = ub913_gpio_of_xlate;
        gc->of_gpio_n_cells = 2;

        ret = gpiochip_add_data(gc, priv);
        if (ret) {
                dev_err(dev, "Failed to add GPIOs: %d\n", ret);
                return ret;
        }

        return 0;
}

static void ub913_gpiochip_remove(struct ub913_data *priv)
{
        gpiochip_remove(&priv->gpio_chip);
}

static const struct regmap_config ub913_regmap_config = {
        .name = "ds90ub913",
        .reg_bits = 8,
        .val_bits = 8,
        .reg_format_endian = REGMAP_ENDIAN_DEFAULT,
        .val_format_endian = REGMAP_ENDIAN_DEFAULT,
};

/*
 * V4L2
 */

static int ub913_enable_streams(struct v4l2_subdev *sd,
                                struct v4l2_subdev_state *state, u32 pad,
                                u64 streams_mask)
{
        struct ub913_data *priv = sd_to_ub913(sd);
        u64 sink_streams;
        int ret;

        sink_streams = v4l2_subdev_state_xlate_streams(state, UB913_PAD_SOURCE,
                                                       UB913_PAD_SINK,
                                                       &streams_mask);

        ret = v4l2_subdev_enable_streams(priv->source_sd, priv->source_sd_pad,
                                         sink_streams);
        if (ret)
                return ret;

        priv->enabled_source_streams |= streams_mask;

        return 0;
}

static int ub913_disable_streams(struct v4l2_subdev *sd,
                                 struct v4l2_subdev_state *state, u32 pad,
                                 u64 streams_mask)
{
        struct ub913_data *priv = sd_to_ub913(sd);
        u64 sink_streams;
        int ret;

        sink_streams = v4l2_subdev_state_xlate_streams(state, UB913_PAD_SOURCE,
                                                       UB913_PAD_SINK,
                                                       &streams_mask);

        ret = v4l2_subdev_disable_streams(priv->source_sd, priv->source_sd_pad,
                                          sink_streams);
        if (ret)
                return ret;

        priv->enabled_source_streams &= ~streams_mask;

        return 0;
}

static int _ub913_set_routing(struct v4l2_subdev *sd,
                              struct v4l2_subdev_state *state,
                              struct v4l2_subdev_krouting *routing)
{
        static const struct v4l2_mbus_framefmt in_format = {
                .width = 640,
                .height = 480,
                .code = MEDIA_BUS_FMT_UYVY8_2X8,
                .field = V4L2_FIELD_NONE,
                .colorspace = V4L2_COLORSPACE_SRGB,
                .ycbcr_enc = V4L2_YCBCR_ENC_601,
                .quantization = V4L2_QUANTIZATION_LIM_RANGE,
                .xfer_func = V4L2_XFER_FUNC_SRGB,
        };
        static const struct v4l2_mbus_framefmt out_format = {
                .width = 640,
                .height = 480,
                .code = MEDIA_BUS_FMT_UYVY8_1X16,
                .field = V4L2_FIELD_NONE,
                .colorspace = V4L2_COLORSPACE_SRGB,
                .ycbcr_enc = V4L2_YCBCR_ENC_601,
                .quantization = V4L2_QUANTIZATION_LIM_RANGE,
                .xfer_func = V4L2_XFER_FUNC_SRGB,
        };
        struct v4l2_subdev_route *route;
        int ret;

        ret = v4l2_subdev_routing_validate(sd, routing,
                                           V4L2_SUBDEV_ROUTING_ONLY_1_TO_1);
        if (ret)
                return ret;

        ret = v4l2_subdev_set_routing(sd, state, routing);
        if (ret)
                return ret;

        for_each_active_route(&state->routing, route) {
                struct v4l2_mbus_framefmt *fmt;

                fmt = v4l2_subdev_state_get_format(state, route->sink_pad,
                                                   route->sink_stream);
                *fmt = in_format;
                fmt = v4l2_subdev_state_get_format(state, route->source_pad,
                                                   route->source_stream);
                *fmt = out_format;
        }

        return 0;
}

static int ub913_set_routing(struct v4l2_subdev *sd,
                             struct v4l2_subdev_state *state,
                             enum v4l2_subdev_format_whence which,
                             struct v4l2_subdev_krouting *routing)
{
        struct ub913_data *priv = sd_to_ub913(sd);

        if (which == V4L2_SUBDEV_FORMAT_ACTIVE && priv->enabled_source_streams)
                return -EBUSY;

        return _ub913_set_routing(sd, state, routing);
}

static int ub913_get_frame_desc(struct v4l2_subdev *sd, unsigned int pad,
                                struct v4l2_mbus_frame_desc *fd)
{
        struct ub913_data *priv = sd_to_ub913(sd);
        const struct v4l2_subdev_krouting *routing;
        struct v4l2_mbus_frame_desc source_fd;
        struct v4l2_subdev_route *route;
        struct v4l2_subdev_state *state;
        int ret;

        if (pad != UB913_PAD_SOURCE)
                return -EINVAL;

        ret = v4l2_subdev_call(priv->source_sd, pad, get_frame_desc,
                               priv->source_sd_pad, &source_fd);
        if (ret)
                return ret;

        fd->type = V4L2_MBUS_FRAME_DESC_TYPE_PARALLEL;

        state = v4l2_subdev_lock_and_get_active_state(sd);

        routing = &state->routing;

        for_each_active_route(routing, route) {
                unsigned int i;

                if (route->source_pad != pad)
                        continue;

                for (i = 0; i < source_fd.num_entries; i++) {
                        if (source_fd.entry[i].stream == route->sink_stream)
                                break;
                }

                if (i == source_fd.num_entries) {
                        dev_err(&priv->client->dev,
                                "Failed to find stream from source frame desc\n");
                        ret = -EPIPE;
                        goto out_unlock;
                }

                fd->entry[fd->num_entries].stream = route->source_stream;
                fd->entry[fd->num_entries].flags = source_fd.entry[i].flags;
                fd->entry[fd->num_entries].length = source_fd.entry[i].length;
                fd->entry[fd->num_entries].pixelcode =
                        source_fd.entry[i].pixelcode;

                fd->num_entries++;
        }

out_unlock:
        v4l2_subdev_unlock_state(state);

        return ret;
}

static int ub913_set_fmt(struct v4l2_subdev *sd,
                         struct v4l2_subdev_state *state,
                         struct v4l2_subdev_format *format)
{
        struct ub913_data *priv = sd_to_ub913(sd);
        struct v4l2_mbus_framefmt *fmt;
        const struct ub913_format_info *finfo;

        if (format->which == V4L2_SUBDEV_FORMAT_ACTIVE &&
            priv->enabled_source_streams)
                return -EBUSY;

        /* Source format is fully defined by the sink format, so not settable */
        if (format->pad == UB913_PAD_SOURCE)
                return v4l2_subdev_get_fmt(sd, state, format);

        finfo = ub913_find_format(format->format.code);
        if (!finfo) {
                finfo = &ub913_formats[0];
                format->format.code = finfo->incode;
        }

        /* Set sink format */
        fmt = v4l2_subdev_state_get_format(state, format->pad, format->stream);
        if (!fmt)
                return -EINVAL;

        *fmt = format->format;

        /* Propagate to source format, and adjust the mbus code */
        fmt = v4l2_subdev_state_get_opposite_stream_format(state, format->pad,
                                                           format->stream);
        if (!fmt)
                return -EINVAL;

        *fmt = format->format;

        fmt->code = finfo->outcode;

        return 0;
}

static int ub913_init_state(struct v4l2_subdev *sd,
                            struct v4l2_subdev_state *state)
{
        struct v4l2_subdev_route routes[] = {
                {
                        .sink_pad = UB913_PAD_SINK,
                        .sink_stream = 0,
                        .source_pad = UB913_PAD_SOURCE,
                        .source_stream = 0,
                        .flags = V4L2_SUBDEV_ROUTE_FL_ACTIVE,
                },
        };

        struct v4l2_subdev_krouting routing = {
                .num_routes = ARRAY_SIZE(routes),
                .routes = routes,
        };

        return _ub913_set_routing(sd, state, &routing);
}

static int ub913_log_status(struct v4l2_subdev *sd)
{
        struct ub913_data *priv = sd_to_ub913(sd);
        struct device *dev = &priv->client->dev;
        u8 v, v1, v2;
        int ret;

        ret = ub913_read(priv, UB913_REG_MODE_SEL, &v, NULL);
        if (ret)
                return ret;

        dev_info(dev, "MODE_SEL %#02x\n", v);

        ub913_read(priv, UB913_REG_CRC_ERRORS_LSB, &v1, &ret);
        ub913_read(priv, UB913_REG_CRC_ERRORS_MSB, &v2, &ret);
        if (ret)
                return ret;

        dev_info(dev, "CRC errors %u\n", v1 | (v2 << 8));

        /* clear CRC errors */
        ub913_read(priv, UB913_REG_GENERAL_CFG, &v, &ret);
        ub913_write(priv, UB913_REG_GENERAL_CFG,
                    v | UB913_REG_GENERAL_CFG_CRC_ERR_RESET, &ret);
        ub913_write(priv, UB913_REG_GENERAL_CFG, v, &ret);

        if (ret)
                return ret;

        ret = ub913_read(priv, UB913_REG_GENERAL_STATUS, &v, NULL);
        if (ret)
                return ret;

        dev_info(dev, "GENERAL_STATUS %#02x\n", v);

        ret = ub913_read(priv, UB913_REG_PLL_OVR, &v, NULL);
        if (ret)
                return ret;

        dev_info(dev, "PLL_OVR %#02x\n", v);

        return 0;
}

static const struct v4l2_subdev_core_ops ub913_subdev_core_ops = {
        .log_status = ub913_log_status,
};

static const struct v4l2_subdev_pad_ops ub913_pad_ops = {
        .enable_streams = ub913_enable_streams,
        .disable_streams = ub913_disable_streams,
        .set_routing = ub913_set_routing,
        .get_frame_desc = ub913_get_frame_desc,
        .get_fmt = v4l2_subdev_get_fmt,
        .set_fmt = ub913_set_fmt,
};

static const struct v4l2_subdev_ops ub913_subdev_ops = {
        .core = &ub913_subdev_core_ops,
        .pad = &ub913_pad_ops,
};

static const struct v4l2_subdev_internal_ops ub913_internal_ops = {
        .init_state = ub913_init_state,
};

static const struct media_entity_operations ub913_entity_ops = {
        .link_validate = v4l2_subdev_link_validate,
};

static int ub913_notify_bound(struct v4l2_async_notifier *notifier,
                              struct v4l2_subdev *source_subdev,
                              struct v4l2_async_connection *asd)
{
        struct ub913_data *priv = sd_to_ub913(notifier->sd);
        struct device *dev = &priv->client->dev;
        int ret;

        ret = media_entity_get_fwnode_pad(&source_subdev->entity,
                                          source_subdev->fwnode,
                                          MEDIA_PAD_FL_SOURCE);
        if (ret < 0) {
                dev_err(dev, "Failed to find pad for %s\n",
                        source_subdev->name);
                return ret;
        }

        priv->source_sd = source_subdev;
        priv->source_sd_pad = ret;

        ret = media_create_pad_link(&source_subdev->entity, priv->source_sd_pad,
                                    &priv->sd.entity, UB913_PAD_SINK,
                                    MEDIA_LNK_FL_ENABLED |
                                            MEDIA_LNK_FL_IMMUTABLE);
        if (ret) {
                dev_err(dev, "Unable to link %s:%u -> %s:0\n",
                        source_subdev->name, priv->source_sd_pad,
                        priv->sd.name);
                return ret;
        }

        return 0;
}

static const struct v4l2_async_notifier_operations ub913_notify_ops = {
        .bound = ub913_notify_bound,
};

static int ub913_v4l2_notifier_register(struct ub913_data *priv)
{
        struct device *dev = &priv->client->dev;
        struct v4l2_async_connection *asd;
        struct fwnode_handle *ep_fwnode;
        int ret;

        ep_fwnode = fwnode_graph_get_endpoint_by_id(dev_fwnode(dev),
                                                    UB913_PAD_SINK, 0, 0);
        if (!ep_fwnode) {
                dev_err(dev, "No graph endpoint\n");
                return -ENODEV;
        }

        v4l2_async_subdev_nf_init(&priv->notifier, &priv->sd);

        asd = v4l2_async_nf_add_fwnode_remote(&priv->notifier, ep_fwnode,
                                              struct v4l2_async_connection);

        fwnode_handle_put(ep_fwnode);

        if (IS_ERR(asd)) {
                dev_err(dev, "Failed to add subdev: %pe", asd);
                v4l2_async_nf_cleanup(&priv->notifier);
                return PTR_ERR(asd);
        }

        priv->notifier.ops = &ub913_notify_ops;

        ret = v4l2_async_nf_register(&priv->notifier);
        if (ret) {
                dev_err(dev, "Failed to register subdev_notifier");
                v4l2_async_nf_cleanup(&priv->notifier);
                return ret;
        }

        return 0;
}

static void ub913_v4l2_nf_unregister(struct ub913_data *priv)
{
        v4l2_async_nf_unregister(&priv->notifier);
        v4l2_async_nf_cleanup(&priv->notifier);
}

static int ub913_register_clkout(struct ub913_data *priv)
{
        struct device *dev = &priv->client->dev;
        const char *name;
        int ret;

        name = kasprintf(GFP_KERNEL, "ds90ub913.%s.clk_out", dev_name(dev));
        if (!name)
                return -ENOMEM;

        priv->clkout_clk_hw = devm_clk_hw_register_fixed_factor(dev, name,
                __clk_get_name(priv->clkin), 0, 1, 2);

        kfree(name);

        if (IS_ERR(priv->clkout_clk_hw))
                return dev_err_probe(dev, PTR_ERR(priv->clkout_clk_hw),
                                     "Cannot register clkout hw\n");

        ret = devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get,
                                          priv->clkout_clk_hw);
        if (ret)
                return dev_err_probe(dev, ret,
                                     "Cannot add OF clock provider\n");

        return 0;
}

static int ub913_i2c_master_init(struct ub913_data *priv)
{
        /* i2c fast mode */
        u32 scl_high = 600 + 300; /* high period + rise time, ns */
        u32 scl_low = 1300 + 300; /* low period + fall time, ns */
        unsigned long ref;
        int ret;

        ref = clk_get_rate(priv->clkin) / 2;

        scl_high = div64_u64((u64)scl_high * ref, 1000000000);
        scl_low = div64_u64((u64)scl_low * ref, 1000000000);

        ret = ub913_write(priv, UB913_REG_SCL_HIGH_TIME, scl_high, NULL);
        if (ret)
                return ret;

        ret = ub913_write(priv, UB913_REG_SCL_LOW_TIME, scl_low, NULL);
        if (ret)
                return ret;

        return 0;
}

static int ub913_add_i2c_adapter(struct ub913_data *priv)
{
        struct device *dev = &priv->client->dev;
        struct i2c_atr_adap_desc desc = { };
        struct fwnode_handle *i2c_handle;
        int ret;

        i2c_handle = device_get_named_child_node(dev, "i2c");
        if (!i2c_handle)
                return 0;

        desc.chan_id = priv->plat_data->port;
        desc.parent = dev;
        desc.bus_handle = i2c_handle;
        desc.num_aliases = 0;

        ret = i2c_atr_add_adapter(priv->plat_data->atr, &desc);

        fwnode_handle_put(i2c_handle);

        if (ret)
                return ret;

        return 0;
}

static int ub913_parse_dt(struct ub913_data *priv)
{
        struct device *dev = &priv->client->dev;
        struct v4l2_fwnode_endpoint vep = {
                .bus_type = V4L2_MBUS_PARALLEL,
        };
        struct fwnode_handle *ep_fwnode;
        int ret;

        ep_fwnode = fwnode_graph_get_endpoint_by_id(dev_fwnode(dev),
                                                    UB913_PAD_SINK, 0, 0);
        if (!ep_fwnode)
                return dev_err_probe(dev, -ENOENT, "No sink endpoint\n");

        ret = v4l2_fwnode_endpoint_parse(ep_fwnode, &vep);

        fwnode_handle_put(ep_fwnode);

        if (ret)
                return dev_err_probe(dev, ret,
                                     "failed to parse sink endpoint data\n");

        if (vep.bus.parallel.flags & V4L2_MBUS_PCLK_SAMPLE_RISING)
                priv->pclk_polarity_rising = true;
        else if (vep.bus.parallel.flags & V4L2_MBUS_PCLK_SAMPLE_FALLING)
                priv->pclk_polarity_rising = false;
        else
                return dev_err_probe(dev, -EINVAL,
                                     "bad value for 'pclk-sample'\n");

        return 0;
}

static int ub913_hw_init(struct ub913_data *priv)
{
        struct device *dev = &priv->client->dev;
        bool mode_override;
        u8 mode;
        int ret;
        u8 v;

        ret = ub913_read(priv, UB913_REG_MODE_SEL, &v, NULL);
        if (ret)
                return ret;

        if (!(v & UB913_REG_MODE_SEL_MODE_UP_TO_DATE))
                return dev_err_probe(dev, -ENODEV,
                                     "Mode value not stabilized\n");

        mode_override = v & UB913_REG_MODE_SEL_MODE_OVERRIDE;
        mode = v & UB913_REG_MODE_SEL_MODE_MASK;

        dev_dbg(dev, "mode from %s: %#x\n",
                mode_override ? "reg" : "deserializer", mode);

        ret = ub913_i2c_master_init(priv);
        if (ret)
                return dev_err_probe(dev, ret, "i2c master init failed\n");

        ret = ub913_update_bits(priv, UB913_REG_GENERAL_CFG,
                                UB913_REG_GENERAL_CFG_PCLK_RISING,
                                FIELD_PREP(UB913_REG_GENERAL_CFG_PCLK_RISING,
                                           priv->pclk_polarity_rising), NULL);

        if (ret)
                return ret;

        return 0;
}

static int ub913_subdev_init(struct ub913_data *priv)
{
        struct device *dev = &priv->client->dev;
        int ret;

        v4l2_i2c_subdev_init(&priv->sd, priv->client, &ub913_subdev_ops);
        priv->sd.internal_ops = &ub913_internal_ops;
        priv->sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE | V4L2_SUBDEV_FL_STREAMS;
        priv->sd.entity.function = MEDIA_ENT_F_VID_IF_BRIDGE;
        priv->sd.entity.ops = &ub913_entity_ops;

        priv->pads[0].flags = MEDIA_PAD_FL_SINK;
        priv->pads[1].flags = MEDIA_PAD_FL_SOURCE;

        ret = media_entity_pads_init(&priv->sd.entity, 2, priv->pads);
        if (ret)
                return dev_err_probe(dev, ret, "Failed to init pads\n");

        ret = v4l2_subdev_init_finalize(&priv->sd);
        if (ret)
                goto err_entity_cleanup;

        ret = ub913_v4l2_notifier_register(priv);
        if (ret) {
                dev_err_probe(dev, ret,
                              "v4l2 subdev notifier register failed\n");
                goto err_subdev_cleanup;
        }

        ret = v4l2_async_register_subdev(&priv->sd);
        if (ret) {
                dev_err_probe(dev, ret, "v4l2_async_register_subdev error\n");
                goto err_unreg_notif;
        }

        return 0;

err_unreg_notif:
        ub913_v4l2_nf_unregister(priv);
err_subdev_cleanup:
        v4l2_subdev_cleanup(&priv->sd);
err_entity_cleanup:
        media_entity_cleanup(&priv->sd.entity);

        return ret;
}

static void ub913_subdev_uninit(struct ub913_data *priv)
{
        v4l2_async_unregister_subdev(&priv->sd);
        ub913_v4l2_nf_unregister(priv);
        v4l2_subdev_cleanup(&priv->sd);
        media_entity_cleanup(&priv->sd.entity);
}

static int ub913_probe(struct i2c_client *client)
{
        struct device *dev = &client->dev;
        struct ub913_data *priv;
        int ret;

        priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
        if (!priv)
                return -ENOMEM;

        priv->client = client;

        priv->plat_data = dev_get_platdata(&client->dev);
        if (!priv->plat_data)
                return dev_err_probe(dev, -ENODEV, "Platform data missing\n");

        priv->regmap = devm_regmap_init_i2c(client, &ub913_regmap_config);
        if (IS_ERR(priv->regmap))
                return dev_err_probe(dev, PTR_ERR(priv->regmap),
                                     "Failed to init regmap\n");

        /*
         * ub913 can also work without ext clock, but that is not supported by
         * the driver yet.
         */
        priv->clkin = devm_clk_get(dev, "clkin");
        if (IS_ERR(priv->clkin))
                return dev_err_probe(dev, PTR_ERR(priv->clkin),
                                     "Cannot get CLKIN\n");

        ret = ub913_parse_dt(priv);
        if (ret)
                return ret;

        ret = ub913_hw_init(priv);
        if (ret)
                return ret;

        ret = ub913_gpiochip_probe(priv);
        if (ret)
                return dev_err_probe(dev, ret, "Failed to init gpiochip\n");

        ret = ub913_register_clkout(priv);
        if (ret) {
                dev_err_probe(dev, ret, "Failed to register clkout\n");
                goto err_gpiochip_remove;
        }

        ret = ub913_subdev_init(priv);
        if (ret)
                goto err_gpiochip_remove;

        ret = ub913_add_i2c_adapter(priv);
        if (ret) {
                dev_err_probe(dev, ret, "failed to add remote i2c adapter\n");
                goto err_subdev_uninit;
        }

        return 0;

err_subdev_uninit:
        ub913_subdev_uninit(priv);
err_gpiochip_remove:
        ub913_gpiochip_remove(priv);

        return ret;
}

static void ub913_remove(struct i2c_client *client)
{
        struct v4l2_subdev *sd = i2c_get_clientdata(client);
        struct ub913_data *priv = sd_to_ub913(sd);

        i2c_atr_del_adapter(priv->plat_data->atr, priv->plat_data->port);

        ub913_subdev_uninit(priv);

        ub913_gpiochip_remove(priv);
}

static const struct i2c_device_id ub913_id[] = {
        { "ds90ub913a-q1" },
        {}
};
MODULE_DEVICE_TABLE(i2c, ub913_id);

static const struct of_device_id ub913_dt_ids[] = {
        { .compatible = "ti,ds90ub913a-q1" },
        {}
};
MODULE_DEVICE_TABLE(of, ub913_dt_ids);

static struct i2c_driver ds90ub913_driver = {
        .probe          = ub913_probe,
        .remove         = ub913_remove,
        .id_table       = ub913_id,
        .driver = {
                .name   = "ds90ub913a",
                .of_match_table = ub913_dt_ids,
        },
};
module_i2c_driver(ds90ub913_driver);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("Texas Instruments DS90UB913 FPD-Link III Serializer Driver");
MODULE_AUTHOR("Luca Ceresoli <luca@lucaceresoli.net>");
MODULE_AUTHOR("Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>");
MODULE_IMPORT_NS("I2C_ATR");