// SPDX-License-Identifier: GPL-2.0-only
/*
 * et8ek8_driver.c
 *
 * Copyright (C) 2008 Nokia Corporation
 *
 * Contact: Sakari Ailus <sakari.ailus@iki.fi>
 *          Tuukka Toivonen <tuukkat76@gmail.com>
 *          Pavel Machek <pavel@ucw.cz>
 *
 * Based on code from Toni Leinonen <toni.leinonen@offcode.fi>.
 *
 * This driver is based on the Micron MT9T012 camera imager driver
 * (C) Texas Instruments.
 */

#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/gpio/consumer.h>
#include <linux/i2c.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/regulator/consumer.h>
#include <linux/slab.h>
#include <linux/sort.h>
#include <linux/v4l2-mediabus.h>

#include <media/media-entity.h>
#include <media/v4l2-ctrls.h>
#include <media/v4l2-device.h>
#include <media/v4l2-subdev.h>

#include "et8ek8_reg.h"

#define ET8EK8_NAME             "et8ek8"
#define ET8EK8_PRIV_MEM_SIZE    128
#define ET8EK8_MAX_MSG          8

struct et8ek8_sensor {
        struct v4l2_subdev subdev;
        struct media_pad pad;
        struct v4l2_mbus_framefmt format;
        struct gpio_desc *reset;
        struct regulator *vana;
        struct clk *ext_clk;
        u32 xclk_freq;

        u16 version;

        struct v4l2_ctrl_handler ctrl_handler;
        struct v4l2_ctrl *exposure;
        struct v4l2_ctrl *pixel_rate;
        struct et8ek8_reglist *current_reglist;

        u8 priv_mem[ET8EK8_PRIV_MEM_SIZE];

        struct mutex power_lock;
        int power_count;
};

#define to_et8ek8_sensor(sd)    container_of(sd, struct et8ek8_sensor, subdev)

enum et8ek8_versions {
        ET8EK8_REV_1 = 0x0001,
        ET8EK8_REV_2,
};

/*
 * This table describes what should be written to the sensor register
 * for each gain value. The gain(index in the table) is in terms of
 * 0.1EV, i.e. 10 indexes in the table give 2 time more gain [0] in
 * the *analog gain, [1] in the digital gain
 *
 * Analog gain [dB] = 20*log10(regvalue/32); 0x20..0x100
 */
static struct et8ek8_gain {
        u16 analog;
        u16 digital;
} const et8ek8_gain_table[] = {
        { 32,    0},  /* x1 */
        { 34,    0},
        { 37,    0},
        { 39,    0},
        { 42,    0},
        { 45,    0},
        { 49,    0},
        { 52,    0},
        { 56,    0},
        { 60,    0},
        { 64,    0},  /* x2 */
        { 69,    0},
        { 74,    0},
        { 79,    0},
        { 84,    0},
        { 91,    0},
        { 97,    0},
        {104,    0},
        {111,    0},
        {119,    0},
        {128,    0},  /* x4 */
        {137,    0},
        {147,    0},
        {158,    0},
        {169,    0},
        {181,    0},
        {194,    0},
        {208,    0},
        {223,    0},
        {239,    0},
        {256,    0},  /* x8 */
        {256,   73},
        {256,  152},
        {256,  236},
        {256,  327},
        {256,  424},
        {256,  528},
        {256,  639},
        {256,  758},
        {256,  886},
        {256, 1023},  /* x16 */
};

/* Register definitions */
#define REG_REVISION_NUMBER_L   0x1200
#define REG_REVISION_NUMBER_H   0x1201

#define PRIV_MEM_START_REG      0x0008
#define PRIV_MEM_WIN_SIZE       8

#define ET8EK8_I2C_DELAY        3       /* msec delay b/w accesses */

#define USE_CRC                 1

/*
 * Register access helpers
 *
 * Read a 8/16/32-bit i2c register.  The value is returned in 'val'.
 * Returns zero if successful, or non-zero otherwise.
 */
static int et8ek8_i2c_read_reg(struct i2c_client *client, u16 data_length,
                               u16 reg, u32 *val)
{
        int r;
        struct i2c_msg msg;
        unsigned char data[4];

        if (!client->adapter)
                return -ENODEV;
        if (data_length != ET8EK8_REG_8BIT && data_length != ET8EK8_REG_16BIT)
                return -EINVAL;

        msg.addr = client->addr;
        msg.flags = 0;
        msg.len = 2;
        msg.buf = data;

        /* high byte goes out first */
        data[0] = (u8) (reg >> 8);
        data[1] = (u8) (reg & 0xff);
        r = i2c_transfer(client->adapter, &msg, 1);
        if (r < 0)
                goto err;

        msg.len = data_length;
        msg.flags = I2C_M_RD;
        r = i2c_transfer(client->adapter, &msg, 1);
        if (r < 0)
                goto err;

        *val = 0;
        /* high byte comes first */
        if (data_length == ET8EK8_REG_8BIT)
                *val = data[0];
        else
                *val = (data[1] << 8) + data[0];

        return 0;

err:
        dev_err(&client->dev, "read from offset 0x%x error %d\n", reg, r);

        return r;
}

static void et8ek8_i2c_create_msg(struct i2c_client *client, u16 len, u16 reg,
                                  u32 val, struct i2c_msg *msg,
                                  unsigned char *buf)
{
        msg->addr = client->addr;
        msg->flags = 0; /* Write */
        msg->len = 2 + len;
        msg->buf = buf;

        /* high byte goes out first */
        buf[0] = (u8) (reg >> 8);
        buf[1] = (u8) (reg & 0xff);

        switch (len) {
        case ET8EK8_REG_8BIT:
                buf[2] = (u8) (val) & 0xff;
                break;
        case ET8EK8_REG_16BIT:
                buf[2] = (u8) (val) & 0xff;
                buf[3] = (u8) (val >> 8) & 0xff;
                break;
        default:
                WARN_ONCE(1, ET8EK8_NAME ": %s: invalid message length.\n",
                          __func__);
        }
}

/*
 * A buffered write method that puts the wanted register write
 * commands in smaller number of message lists and passes the lists to
 * the i2c framework
 */
static int et8ek8_i2c_buffered_write_regs(struct i2c_client *client,
                                          const struct et8ek8_reg *wnext,
                                          int cnt)
{
        struct i2c_msg msg[ET8EK8_MAX_MSG];
        unsigned char data[ET8EK8_MAX_MSG][6];
        int wcnt = 0;
        u16 reg, data_length;
        u32 val;
        int rval;

        /* Create new write messages for all writes */
        while (wcnt < cnt) {
                data_length = wnext->type;
                reg = wnext->reg;
                val = wnext->val;
                wnext++;

                et8ek8_i2c_create_msg(client, data_length, reg,
                                    val, &msg[wcnt], &data[wcnt][0]);

                /* Update write count */
                wcnt++;

                if (wcnt < ET8EK8_MAX_MSG)
                        continue;

                rval = i2c_transfer(client->adapter, msg, wcnt);
                if (rval < 0)
                        return rval;

                cnt -= wcnt;
                wcnt = 0;
        }

        rval = i2c_transfer(client->adapter, msg, wcnt);

        return rval < 0 ? rval : 0;
}

/*
 * Write a list of registers to i2c device.
 *
 * The list of registers is terminated by ET8EK8_REG_TERM.
 * Returns zero if successful, or non-zero otherwise.
 */
static int et8ek8_i2c_write_regs(struct i2c_client *client,
                                 const struct et8ek8_reg *regs)
{
        int r, cnt = 0;
        const struct et8ek8_reg *next;

        if (!client->adapter)
                return -ENODEV;

        if (!regs)
                return -EINVAL;

        /* Initialize list pointers to the start of the list */
        next = regs;

        do {
                /*
                 * We have to go through the list to figure out how
                 * many regular writes we have in a row
                 */
                while (next->type != ET8EK8_REG_TERM &&
                       next->type != ET8EK8_REG_DELAY) {
                        /*
                         * Here we check that the actual length fields
                         * are valid
                         */
                        if (WARN(next->type != ET8EK8_REG_8BIT &&
                                 next->type != ET8EK8_REG_16BIT,
                                 "Invalid type = %d", next->type)) {
                                return -EINVAL;
                        }
                        /*
                         * Increment count of successive writes and
                         * read pointer
                         */
                        cnt++;
                        next++;
                }

                /* Now we start writing ... */
                r = et8ek8_i2c_buffered_write_regs(client, regs, cnt);

                /* ... and then check that everything was OK */
                if (r < 0) {
                        dev_err(&client->dev, "i2c transfer error!\n");
                        return r;
                }

                /*
                 * If we ran into a sleep statement when going through
                 * the list, this is where we snooze for the required time
                 */
                if (next->type == ET8EK8_REG_DELAY) {
                        msleep(next->val);
                        /*
                         * ZZZ ...
                         * Update list pointers and cnt and start over ...
                         */
                        next++;
                        regs = next;
                        cnt = 0;
                }
        } while (next->type != ET8EK8_REG_TERM);

        return 0;
}

/*
 * Write to a 8/16-bit register.
 * Returns zero if successful, or non-zero otherwise.
 */
static int et8ek8_i2c_write_reg(struct i2c_client *client, u16 data_length,
                                u16 reg, u32 val)
{
        int r;
        struct i2c_msg msg;
        unsigned char data[6];

        if (!client->adapter)
                return -ENODEV;
        if (data_length != ET8EK8_REG_8BIT && data_length != ET8EK8_REG_16BIT)
                return -EINVAL;

        et8ek8_i2c_create_msg(client, data_length, reg, val, &msg, data);

        r = i2c_transfer(client->adapter, &msg, 1);
        if (r < 0) {
                dev_err(&client->dev,
                        "wrote 0x%x to offset 0x%x error %d\n", val, reg, r);
                return r;
        }

        return 0;
}

static struct et8ek8_reglist *et8ek8_reglist_find_type(
                struct et8ek8_meta_reglist *meta,
                u16 type)
{
        struct et8ek8_reglist **next = &meta->reglist[0].ptr;

        while (*next) {
                if ((*next)->type == type)
                        return *next;

                next++;
        }

        return NULL;
}

static int et8ek8_i2c_reglist_find_write(struct i2c_client *client,
                                         struct et8ek8_meta_reglist *meta,
                                         u16 type)
{
        struct et8ek8_reglist *reglist;

        reglist = et8ek8_reglist_find_type(meta, type);
        if (!reglist)
                return -EINVAL;

        return et8ek8_i2c_write_regs(client, reglist->regs);
}

static struct et8ek8_reglist **et8ek8_reglist_first(
                struct et8ek8_meta_reglist *meta)
{
        return &meta->reglist[0].ptr;
}

static void et8ek8_reglist_to_mbus(const struct et8ek8_reglist *reglist,
                                   struct v4l2_mbus_framefmt *fmt)
{
        fmt->width = reglist->mode.window_width;
        fmt->height = reglist->mode.window_height;
        fmt->code = reglist->mode.bus_format;
}

static struct et8ek8_reglist *et8ek8_reglist_find_mode_fmt(
                struct et8ek8_meta_reglist *meta,
                struct v4l2_mbus_framefmt *fmt)
{
        struct et8ek8_reglist **list = et8ek8_reglist_first(meta);
        struct et8ek8_reglist *best_match = NULL;
        struct et8ek8_reglist *best_other = NULL;
        struct v4l2_mbus_framefmt format;
        unsigned int max_dist_match = (unsigned int)-1;
        unsigned int max_dist_other = (unsigned int)-1;

        /*
         * Find the mode with the closest image size. The distance between
         * image sizes is the size in pixels of the non-overlapping regions
         * between the requested size and the frame-specified size.
         *
         * Store both the closest mode that matches the requested format, and
         * the closest mode for all other formats. The best match is returned
         * if found, otherwise the best mode with a non-matching format is
         * returned.
         */
        for (; *list; list++) {
                unsigned int dist;

                if ((*list)->type != ET8EK8_REGLIST_MODE)
                        continue;

                et8ek8_reglist_to_mbus(*list, &format);

                dist = min(fmt->width, format.width)
                     * min(fmt->height, format.height);
                dist = format.width * format.height
                     + fmt->width * fmt->height - 2 * dist;


                if (fmt->code == format.code) {
                        if (dist < max_dist_match || !best_match) {
                                best_match = *list;
                                max_dist_match = dist;
                        }
                } else {
                        if (dist < max_dist_other || !best_other) {
                                best_other = *list;
                                max_dist_other = dist;
                        }
                }
        }

        return best_match ? best_match : best_other;
}

#define TIMEPERFRAME_AVG_FPS(t)                                         \
        (((t).denominator + ((t).numerator >> 1)) / (t).numerator)

static struct et8ek8_reglist *et8ek8_reglist_find_mode_ival(
                struct et8ek8_meta_reglist *meta,
                struct et8ek8_reglist *current_reglist,
                struct v4l2_fract *timeperframe)
{
        int fps = TIMEPERFRAME_AVG_FPS(*timeperframe);
        struct et8ek8_reglist **list = et8ek8_reglist_first(meta);
        struct et8ek8_mode *current_mode = &current_reglist->mode;

        for (; *list; list++) {
                struct et8ek8_mode *mode = &(*list)->mode;

                if ((*list)->type != ET8EK8_REGLIST_MODE)
                        continue;

                if (mode->window_width != current_mode->window_width ||
                    mode->window_height != current_mode->window_height)
                        continue;

                if (TIMEPERFRAME_AVG_FPS(mode->timeperframe) == fps)
                        return *list;
        }

        return NULL;
}

static int et8ek8_reglist_cmp(const void *a, const void *b)
{
        const struct et8ek8_reglist **list1 = (const struct et8ek8_reglist **)a,
                **list2 = (const struct et8ek8_reglist **)b;

        /* Put real modes in the beginning. */
        if ((*list1)->type == ET8EK8_REGLIST_MODE &&
            (*list2)->type != ET8EK8_REGLIST_MODE)
                return -1;
        if ((*list1)->type != ET8EK8_REGLIST_MODE &&
            (*list2)->type == ET8EK8_REGLIST_MODE)
                return 1;

        /* Descending width. */
        if ((*list1)->mode.window_width > (*list2)->mode.window_width)
                return -1;
        if ((*list1)->mode.window_width < (*list2)->mode.window_width)
                return 1;

        if ((*list1)->mode.window_height > (*list2)->mode.window_height)
                return -1;
        if ((*list1)->mode.window_height < (*list2)->mode.window_height)
                return 1;

        return 0;
}

static int et8ek8_reglist_import(struct i2c_client *client,
                                 struct et8ek8_meta_reglist *meta)
{
        int nlists = 0, i;

        dev_info(&client->dev, "meta_reglist version %s\n", meta->version);

        while (meta->reglist[nlists].ptr)
                nlists++;

        if (!nlists)
                return -EINVAL;

        sort(&meta->reglist[0].ptr, nlists, sizeof(meta->reglist[0].ptr),
             et8ek8_reglist_cmp, NULL);

        i = nlists;
        nlists = 0;

        while (i--) {
                struct et8ek8_reglist *list;

                list = meta->reglist[nlists].ptr;

                dev_dbg(&client->dev,
                       "%s: type %d\tw %d\th %d\tfmt %x\tival %d/%d\tptr %p\n",
                       __func__,
                       list->type,
                       list->mode.window_width, list->mode.window_height,
                       list->mode.bus_format,
                       list->mode.timeperframe.numerator,
                       list->mode.timeperframe.denominator,
                       (void *)meta->reglist[nlists].ptr);

                nlists++;
        }

        return 0;
}

/* Called to change the V4L2 gain control value. This function
 * rounds and clamps the given value and updates the V4L2 control value.
 * If power is on, also updates the sensor analog and digital gains.
 * gain is in 0.1 EV (exposure value) units.
 */
static int et8ek8_set_gain(struct et8ek8_sensor *sensor, s32 gain)
{
        struct i2c_client *client = v4l2_get_subdevdata(&sensor->subdev);
        struct et8ek8_gain new;
        int r;

        new = et8ek8_gain_table[gain];

        /* FIXME: optimise I2C writes! */
        r = et8ek8_i2c_write_reg(client, ET8EK8_REG_8BIT,
                                0x124a, new.analog >> 8);
        if (r)
                return r;
        r = et8ek8_i2c_write_reg(client, ET8EK8_REG_8BIT,
                                0x1249, new.analog & 0xff);
        if (r)
                return r;

        r = et8ek8_i2c_write_reg(client, ET8EK8_REG_8BIT,
                                0x124d, new.digital >> 8);
        if (r)
                return r;
        r = et8ek8_i2c_write_reg(client, ET8EK8_REG_8BIT,
                                0x124c, new.digital & 0xff);

        return r;
}

static int et8ek8_set_test_pattern(struct et8ek8_sensor *sensor, s32 mode)
{
        struct i2c_client *client = v4l2_get_subdevdata(&sensor->subdev);
        int cbh_mode, cbv_mode, tp_mode, din_sw, r1420, rval;

        /* Values for normal mode */
        cbh_mode = 0;
        cbv_mode = 0;
        tp_mode  = 0;
        din_sw   = 0x00;
        r1420    = 0xF0;

        if (mode) {
                /* Test pattern mode */
                if (mode < 5) {
                        cbh_mode = 1;
                        cbv_mode = 1;
                        tp_mode  = mode + 3;
                } else {
                        cbh_mode = 0;
                        cbv_mode = 0;
                        tp_mode  = mode - 4 + 3;
                }

                din_sw   = 0x01;
                r1420    = 0xE0;
        }

        rval = et8ek8_i2c_write_reg(client, ET8EK8_REG_8BIT, 0x111B,
                                    tp_mode << 4);
        if (rval)
                return rval;

        rval = et8ek8_i2c_write_reg(client, ET8EK8_REG_8BIT, 0x1121,
                                    cbh_mode << 7);
        if (rval)
                return rval;

        rval = et8ek8_i2c_write_reg(client, ET8EK8_REG_8BIT, 0x1124,
                                    cbv_mode << 7);
        if (rval)
                return rval;

        rval = et8ek8_i2c_write_reg(client, ET8EK8_REG_8BIT, 0x112C, din_sw);
        if (rval)
                return rval;

        return et8ek8_i2c_write_reg(client, ET8EK8_REG_8BIT, 0x1420, r1420);
}

/* -----------------------------------------------------------------------------
 * V4L2 controls
 */

static int et8ek8_set_ctrl(struct v4l2_ctrl *ctrl)
{
        struct et8ek8_sensor *sensor =
                container_of(ctrl->handler, struct et8ek8_sensor, ctrl_handler);

        switch (ctrl->id) {
        case V4L2_CID_GAIN:
                return et8ek8_set_gain(sensor, ctrl->val);

        case V4L2_CID_EXPOSURE:
        {
                struct i2c_client *client =
                        v4l2_get_subdevdata(&sensor->subdev);

                return et8ek8_i2c_write_reg(client, ET8EK8_REG_16BIT, 0x1243,
                                            ctrl->val);
        }

        case V4L2_CID_TEST_PATTERN:
                return et8ek8_set_test_pattern(sensor, ctrl->val);

        case V4L2_CID_PIXEL_RATE:
                return 0;

        default:
                return -EINVAL;
        }
}

static const struct v4l2_ctrl_ops et8ek8_ctrl_ops = {
        .s_ctrl = et8ek8_set_ctrl,
};

static const char * const et8ek8_test_pattern_menu[] = {
        "Normal",
        "Vertical colorbar",
        "Horizontal colorbar",
        "Scale",
        "Ramp",
        "Small vertical colorbar",
        "Small horizontal colorbar",
        "Small scale",
        "Small ramp",
};

static int et8ek8_init_controls(struct et8ek8_sensor *sensor)
{
        s32 max_rows;

        v4l2_ctrl_handler_init(&sensor->ctrl_handler, 4);

        /* V4L2_CID_GAIN */
        v4l2_ctrl_new_std(&sensor->ctrl_handler, &et8ek8_ctrl_ops,
                          V4L2_CID_GAIN, 0, ARRAY_SIZE(et8ek8_gain_table) - 1,
                          1, 0);

        max_rows = sensor->current_reglist->mode.max_exp;
        {
                u32 min = 1, max = max_rows;

                sensor->exposure =
                        v4l2_ctrl_new_std(&sensor->ctrl_handler,
                                          &et8ek8_ctrl_ops, V4L2_CID_EXPOSURE,
                                          min, max, min, max);
        }

        /* V4L2_CID_PIXEL_RATE */
        sensor->pixel_rate =
                v4l2_ctrl_new_std(&sensor->ctrl_handler, &et8ek8_ctrl_ops,
                V4L2_CID_PIXEL_RATE, 1, INT_MAX, 1, 1);

        /* V4L2_CID_TEST_PATTERN */
        v4l2_ctrl_new_std_menu_items(&sensor->ctrl_handler,
                                     &et8ek8_ctrl_ops, V4L2_CID_TEST_PATTERN,
                                     ARRAY_SIZE(et8ek8_test_pattern_menu) - 1,
                                     0, 0, et8ek8_test_pattern_menu);

        if (sensor->ctrl_handler.error)
                return sensor->ctrl_handler.error;

        sensor->subdev.ctrl_handler = &sensor->ctrl_handler;

        return 0;
}

static void et8ek8_update_controls(struct et8ek8_sensor *sensor)
{
        struct v4l2_ctrl *ctrl;
        struct et8ek8_mode *mode = &sensor->current_reglist->mode;

        u32 min, max, pixel_rate;
        static const int S = 8;

        ctrl = sensor->exposure;

        min = 1;
        max = mode->max_exp;

        /*
         * Calculate average pixel clock per line. Assume buffers can spread
         * the data over horizontal blanking time. Rounding upwards.
         * Formula taken from stock Nokia N900 kernel.
         */
        pixel_rate = ((mode->pixel_clock + (1 << S) - 1) >> S) + mode->width;
        pixel_rate = mode->window_width * (pixel_rate - 1) / mode->width;

        __v4l2_ctrl_modify_range(ctrl, min, max, min, max);
        __v4l2_ctrl_s_ctrl_int64(sensor->pixel_rate, pixel_rate << S);
}

static int et8ek8_configure(struct et8ek8_sensor *sensor)
{
        struct v4l2_subdev *subdev = &sensor->subdev;
        struct i2c_client *client = v4l2_get_subdevdata(subdev);
        int rval;

        rval = et8ek8_i2c_write_regs(client, sensor->current_reglist->regs);
        if (rval)
                goto fail;

        /* Controls set while the power to the sensor is turned off are saved
         * but not applied to the hardware. Now that we're about to start
         * streaming apply all the current values to the hardware.
         */
        rval = v4l2_ctrl_handler_setup(&sensor->ctrl_handler);
        if (rval)
                goto fail;

        return 0;

fail:
        dev_err(&client->dev, "sensor configuration failed\n");

        return rval;
}

static int et8ek8_stream_on(struct et8ek8_sensor *sensor)
{
        struct i2c_client *client = v4l2_get_subdevdata(&sensor->subdev);

        return et8ek8_i2c_write_reg(client, ET8EK8_REG_8BIT, 0x1252, 0xb0);
}

static int et8ek8_stream_off(struct et8ek8_sensor *sensor)
{
        struct i2c_client *client = v4l2_get_subdevdata(&sensor->subdev);

        return et8ek8_i2c_write_reg(client, ET8EK8_REG_8BIT, 0x1252, 0x30);
}

static int et8ek8_s_stream(struct v4l2_subdev *subdev, int streaming)
{
        struct et8ek8_sensor *sensor = to_et8ek8_sensor(subdev);
        int ret;

        if (!streaming)
                return et8ek8_stream_off(sensor);

        ret = et8ek8_configure(sensor);
        if (ret < 0)
                return ret;

        return et8ek8_stream_on(sensor);
}

/* --------------------------------------------------------------------------
 * V4L2 subdev operations
 */

static int et8ek8_power_off(struct et8ek8_sensor *sensor)
{
        gpiod_set_value(sensor->reset, 0);
        udelay(1);

        clk_disable_unprepare(sensor->ext_clk);

        return regulator_disable(sensor->vana);
}

static int et8ek8_power_on(struct et8ek8_sensor *sensor)
{
        struct v4l2_subdev *subdev = &sensor->subdev;
        struct i2c_client *client = v4l2_get_subdevdata(subdev);
        int val, rval;

        rval = regulator_enable(sensor->vana);
        if (rval) {
                dev_err(&client->dev, "failed to enable vana regulator\n");
                return rval;
        }

        rval = clk_prepare_enable(sensor->ext_clk);
        if (rval < 0) {
                dev_err(&client->dev, "failed to enable extclk\n");
                goto out;
        }

        if (rval)
                goto out;

        udelay(10); /* I wish this is a good value */

        /*
         * Note: Misinterpretation of reset assertion - do not re-use this code.
         * The reset pin is using incorrect (for a reset signal) logical level.
         */
        gpiod_set_value(sensor->reset, 1);

        msleep(5000 * 1000 / sensor->xclk_freq + 1); /* Wait 5000 cycles */

        rval = et8ek8_i2c_reglist_find_write(client, &meta_reglist,
                                             ET8EK8_REGLIST_POWERON);
        if (rval)
                goto out;

#ifdef USE_CRC
        rval = et8ek8_i2c_read_reg(client, ET8EK8_REG_8BIT, 0x1263, &val);
        if (rval)
                goto out;
#if USE_CRC /* TODO get crc setting from DT */
        val |= BIT(4);
#else
        val &= ~BIT(4);
#endif
        rval = et8ek8_i2c_write_reg(client, ET8EK8_REG_8BIT, 0x1263, val);
        if (rval)
                goto out;
#endif

out:
        if (rval)
                et8ek8_power_off(sensor);

        return rval;
}

/* --------------------------------------------------------------------------
 * V4L2 subdev video operations
 */
#define MAX_FMTS 4
static int et8ek8_enum_mbus_code(struct v4l2_subdev *subdev,
                                 struct v4l2_subdev_state *sd_state,
                                 struct v4l2_subdev_mbus_code_enum *code)
{
        struct et8ek8_reglist **list =
                        et8ek8_reglist_first(&meta_reglist);
        u32 pixelformat[MAX_FMTS];
        int npixelformat = 0;

        if (code->index >= MAX_FMTS)
                return -EINVAL;

        for (; *list; list++) {
                struct et8ek8_mode *mode = &(*list)->mode;
                int i;

                if ((*list)->type != ET8EK8_REGLIST_MODE)
                        continue;

                for (i = 0; i < npixelformat; i++) {
                        if (pixelformat[i] == mode->bus_format)
                                break;
                }
                if (i != npixelformat)
                        continue;

                if (code->index == npixelformat) {
                        code->code = mode->bus_format;
                        return 0;
                }

                pixelformat[npixelformat] = mode->bus_format;
                npixelformat++;
        }

        return -EINVAL;
}

static int et8ek8_enum_frame_size(struct v4l2_subdev *subdev,
                                  struct v4l2_subdev_state *sd_state,
                                  struct v4l2_subdev_frame_size_enum *fse)
{
        struct et8ek8_reglist **list =
                        et8ek8_reglist_first(&meta_reglist);
        struct v4l2_mbus_framefmt format;
        int cmp_width = INT_MAX;
        int cmp_height = INT_MAX;
        int index = fse->index;

        for (; *list; list++) {
                if ((*list)->type != ET8EK8_REGLIST_MODE)
                        continue;

                et8ek8_reglist_to_mbus(*list, &format);
                if (fse->code != format.code)
                        continue;

                /* Assume that the modes are grouped by frame size. */
                if (format.width == cmp_width && format.height == cmp_height)
                        continue;

                cmp_width = format.width;
                cmp_height = format.height;

                if (index-- == 0) {
                        fse->min_width = format.width;
                        fse->min_height = format.height;
                        fse->max_width = format.width;
                        fse->max_height = format.height;
                        return 0;
                }
        }

        return -EINVAL;
}

static int et8ek8_enum_frame_ival(struct v4l2_subdev *subdev,
                                  struct v4l2_subdev_state *sd_state,
                                  struct v4l2_subdev_frame_interval_enum *fie)
{
        struct et8ek8_reglist **list =
                        et8ek8_reglist_first(&meta_reglist);
        struct v4l2_mbus_framefmt format;
        int index = fie->index;

        for (; *list; list++) {
                struct et8ek8_mode *mode = &(*list)->mode;

                if ((*list)->type != ET8EK8_REGLIST_MODE)
                        continue;

                et8ek8_reglist_to_mbus(*list, &format);
                if (fie->code != format.code)
                        continue;

                if (fie->width != format.width || fie->height != format.height)
                        continue;

                if (index-- == 0) {
                        fie->interval = mode->timeperframe;
                        return 0;
                }
        }

        return -EINVAL;
}

static struct v4l2_mbus_framefmt *
__et8ek8_get_pad_format(struct et8ek8_sensor *sensor,
                        struct v4l2_subdev_state *sd_state,
                        unsigned int pad, enum v4l2_subdev_format_whence which)
{
        switch (which) {
        case V4L2_SUBDEV_FORMAT_TRY:
                return v4l2_subdev_state_get_format(sd_state, pad);
        case V4L2_SUBDEV_FORMAT_ACTIVE:
                return &sensor->format;
        default:
                return NULL;
        }
}

static int et8ek8_get_pad_format(struct v4l2_subdev *subdev,
                                 struct v4l2_subdev_state *sd_state,
                                 struct v4l2_subdev_format *fmt)
{
        struct et8ek8_sensor *sensor = to_et8ek8_sensor(subdev);
        struct v4l2_mbus_framefmt *format;

        format = __et8ek8_get_pad_format(sensor, sd_state, fmt->pad,
                                         fmt->which);
        if (!format)
                return -EINVAL;

        fmt->format = *format;

        return 0;
}

static int et8ek8_set_pad_format(struct v4l2_subdev *subdev,
                                 struct v4l2_subdev_state *sd_state,
                                 struct v4l2_subdev_format *fmt)
{
        struct et8ek8_sensor *sensor = to_et8ek8_sensor(subdev);
        struct v4l2_mbus_framefmt *format;
        struct et8ek8_reglist *reglist;

        format = __et8ek8_get_pad_format(sensor, sd_state, fmt->pad,
                                         fmt->which);
        if (!format)
                return -EINVAL;

        reglist = et8ek8_reglist_find_mode_fmt(&meta_reglist, &fmt->format);
        et8ek8_reglist_to_mbus(reglist, &fmt->format);
        *format = fmt->format;

        if (fmt->which == V4L2_SUBDEV_FORMAT_ACTIVE) {
                sensor->current_reglist = reglist;
                et8ek8_update_controls(sensor);
        }

        return 0;
}

static int et8ek8_get_frame_interval(struct v4l2_subdev *subdev,
                                     struct v4l2_subdev_state *sd_state,
                                     struct v4l2_subdev_frame_interval *fi)
{
        struct et8ek8_sensor *sensor = to_et8ek8_sensor(subdev);

        /*
         * FIXME: Implement support for V4L2_SUBDEV_FORMAT_TRY, using the V4L2
         * subdev active state API.
         */
        if (fi->which != V4L2_SUBDEV_FORMAT_ACTIVE)
                return -EINVAL;

        memset(fi, 0, sizeof(*fi));
        fi->interval = sensor->current_reglist->mode.timeperframe;

        return 0;
}

static int et8ek8_set_frame_interval(struct v4l2_subdev *subdev,
                                     struct v4l2_subdev_state *sd_state,
                                     struct v4l2_subdev_frame_interval *fi)
{
        struct et8ek8_sensor *sensor = to_et8ek8_sensor(subdev);
        struct et8ek8_reglist *reglist;

        /*
         * FIXME: Implement support for V4L2_SUBDEV_FORMAT_TRY, using the V4L2
         * subdev active state API.
         */
        if (fi->which != V4L2_SUBDEV_FORMAT_ACTIVE)
                return -EINVAL;

        reglist = et8ek8_reglist_find_mode_ival(&meta_reglist,
                                                sensor->current_reglist,
                                                &fi->interval);

        if (!reglist)
                return -EINVAL;

        sensor->current_reglist = reglist;
        et8ek8_update_controls(sensor);

        return 0;
}

static int et8ek8_g_priv_mem(struct v4l2_subdev *subdev)
{
        struct et8ek8_sensor *sensor = to_et8ek8_sensor(subdev);
        struct i2c_client *client = v4l2_get_subdevdata(subdev);
        unsigned int length = ET8EK8_PRIV_MEM_SIZE;
        unsigned int offset = 0;
        u8 *ptr  = sensor->priv_mem;
        int rval = 0;

        /* Read the EEPROM window-by-window, each window 8 bytes */
        do {
                u8 buffer[PRIV_MEM_WIN_SIZE];
                struct i2c_msg msg;
                int bytes, i;
                int ofs;

                /* Set the current window */
                rval = et8ek8_i2c_write_reg(client, ET8EK8_REG_8BIT, 0x0001,
                                            0xe0 | (offset >> 3));
                if (rval < 0)
                        return rval;

                /* Wait for status bit */
                for (i = 0; i < 1000; ++i) {
                        u32 status;

                        rval = et8ek8_i2c_read_reg(client, ET8EK8_REG_8BIT,
                                                   0x0003, &status);
                        if (rval < 0)
                                return rval;
                        if (!(status & 0x08))
                                break;
                        usleep_range(1000, 2000);
                }

                if (i == 1000)
                        return -EIO;

                /* Read window, 8 bytes at once, and copy to user space */
                ofs = offset & 0x07;    /* Offset within this window */
                bytes = length + ofs > 8 ? 8-ofs : length;
                msg.addr = client->addr;
                msg.flags = 0;
                msg.len = 2;
                msg.buf = buffer;
                ofs += PRIV_MEM_START_REG;
                buffer[0] = (u8)(ofs >> 8);
                buffer[1] = (u8)(ofs & 0xFF);

                rval = i2c_transfer(client->adapter, &msg, 1);
                if (rval < 0)
                        return rval;

                mdelay(ET8EK8_I2C_DELAY);
                msg.addr = client->addr;
                msg.len = bytes;
                msg.flags = I2C_M_RD;
                msg.buf = buffer;
                memset(buffer, 0, sizeof(buffer));

                rval = i2c_transfer(client->adapter, &msg, 1);
                if (rval < 0)
                        return rval;

                rval = 0;
                memcpy(ptr, buffer, bytes);

                length -= bytes;
                offset += bytes;
                ptr += bytes;
        } while (length > 0);

        return rval;
}

static int et8ek8_dev_init(struct v4l2_subdev *subdev)
{
        struct et8ek8_sensor *sensor = to_et8ek8_sensor(subdev);
        struct i2c_client *client = v4l2_get_subdevdata(subdev);
        int rval, rev_l, rev_h;

        rval = et8ek8_power_on(sensor);
        if (rval) {
                dev_err(&client->dev, "could not power on\n");
                return rval;
        }

        rval = et8ek8_i2c_read_reg(client, ET8EK8_REG_8BIT,
                                   REG_REVISION_NUMBER_L, &rev_l);
        if (!rval)
                rval = et8ek8_i2c_read_reg(client, ET8EK8_REG_8BIT,
                                           REG_REVISION_NUMBER_H, &rev_h);
        if (rval) {
                dev_err(&client->dev, "no et8ek8 sensor detected\n");
                goto out_poweroff;
        }

        sensor->version = (rev_h << 8) + rev_l;
        if (sensor->version != ET8EK8_REV_1 && sensor->version != ET8EK8_REV_2)
                dev_info(&client->dev,
                         "unknown version 0x%x detected, continuing anyway\n",
                         sensor->version);

        rval = et8ek8_reglist_import(client, &meta_reglist);
        if (rval) {
                dev_err(&client->dev,
                        "invalid register list %s, import failed\n",
                        ET8EK8_NAME);
                goto out_poweroff;
        }

        sensor->current_reglist = et8ek8_reglist_find_type(&meta_reglist,
                                                           ET8EK8_REGLIST_MODE);
        if (!sensor->current_reglist) {
                dev_err(&client->dev,
                        "invalid register list %s, no mode found\n",
                        ET8EK8_NAME);
                rval = -ENODEV;
                goto out_poweroff;
        }

        et8ek8_reglist_to_mbus(sensor->current_reglist, &sensor->format);

        rval = et8ek8_i2c_reglist_find_write(client, &meta_reglist,
                                             ET8EK8_REGLIST_POWERON);
        if (rval) {
                dev_err(&client->dev,
                        "invalid register list %s, no POWERON mode found\n",
                        ET8EK8_NAME);
                goto out_poweroff;
        }
        rval = et8ek8_stream_on(sensor); /* Needed to be able to read EEPROM */
        if (rval)
                goto out_poweroff;
        rval = et8ek8_g_priv_mem(subdev);
        if (rval)
                dev_warn(&client->dev,
                        "can not read OTP (EEPROM) memory from sensor\n");
        rval = et8ek8_stream_off(sensor);
        if (rval)
                goto out_poweroff;

        rval = et8ek8_power_off(sensor);
        if (rval)
                goto out_poweroff;

        return 0;

out_poweroff:
        et8ek8_power_off(sensor);

        return rval;
}

/* --------------------------------------------------------------------------
 * sysfs attributes
 */
static ssize_t
priv_mem_show(struct device *dev, struct device_attribute *attr, char *buf)
{
        struct v4l2_subdev *subdev = dev_get_drvdata(dev);
        struct et8ek8_sensor *sensor = to_et8ek8_sensor(subdev);

#if PAGE_SIZE < ET8EK8_PRIV_MEM_SIZE
#error PAGE_SIZE too small!
#endif

        memcpy(buf, sensor->priv_mem, ET8EK8_PRIV_MEM_SIZE);

        return ET8EK8_PRIV_MEM_SIZE;
}
static DEVICE_ATTR_RO(priv_mem);

/* --------------------------------------------------------------------------
 * V4L2 subdev core operations
 */

static int
et8ek8_registered(struct v4l2_subdev *subdev)
{
        struct et8ek8_sensor *sensor = to_et8ek8_sensor(subdev);
        struct i2c_client *client = v4l2_get_subdevdata(subdev);
        int rval;

        dev_dbg(&client->dev, "registered!");

        rval = device_create_file(&client->dev, &dev_attr_priv_mem);
        if (rval) {
                dev_err(&client->dev, "could not register sysfs entry\n");
                return rval;
        }

        rval = et8ek8_dev_init(subdev);
        if (rval)
                goto err_file;

        rval = et8ek8_init_controls(sensor);
        if (rval) {
                dev_err(&client->dev, "controls initialization failed\n");
                goto err_file;
        }

        __et8ek8_get_pad_format(sensor, NULL, 0, V4L2_SUBDEV_FORMAT_ACTIVE);

        return 0;

err_file:
        device_remove_file(&client->dev, &dev_attr_priv_mem);

        return rval;
}

static int __et8ek8_set_power(struct et8ek8_sensor *sensor, bool on)
{
        return on ? et8ek8_power_on(sensor) : et8ek8_power_off(sensor);
}

static int et8ek8_set_power(struct v4l2_subdev *subdev, int on)
{
        struct et8ek8_sensor *sensor = to_et8ek8_sensor(subdev);
        int ret = 0;

        mutex_lock(&sensor->power_lock);

        /* If the power count is modified from 0 to != 0 or from != 0 to 0,
         * update the power state.
         */
        if (sensor->power_count == !on) {
                ret = __et8ek8_set_power(sensor, !!on);
                if (ret < 0)
                        goto done;
        }

        /* Update the power count. */
        sensor->power_count += on ? 1 : -1;
        WARN_ON(sensor->power_count < 0);

done:
        mutex_unlock(&sensor->power_lock);

        return ret;
}

static int et8ek8_open(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh)
{
        struct et8ek8_sensor *sensor = to_et8ek8_sensor(sd);
        struct v4l2_mbus_framefmt *format;
        struct et8ek8_reglist *reglist;

        reglist = et8ek8_reglist_find_type(&meta_reglist, ET8EK8_REGLIST_MODE);
        format = __et8ek8_get_pad_format(sensor, fh->state, 0,
                                         V4L2_SUBDEV_FORMAT_TRY);
        et8ek8_reglist_to_mbus(reglist, format);

        return et8ek8_set_power(sd, true);
}

static int et8ek8_close(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh)
{
        return et8ek8_set_power(sd, false);
}

static const struct v4l2_subdev_video_ops et8ek8_video_ops = {
        .s_stream = et8ek8_s_stream,
};

static const struct v4l2_subdev_core_ops et8ek8_core_ops = {
        .s_power = et8ek8_set_power,
};

static const struct v4l2_subdev_pad_ops et8ek8_pad_ops = {
        .enum_mbus_code = et8ek8_enum_mbus_code,
        .enum_frame_size = et8ek8_enum_frame_size,
        .enum_frame_interval = et8ek8_enum_frame_ival,
        .get_fmt = et8ek8_get_pad_format,
        .set_fmt = et8ek8_set_pad_format,
        .get_frame_interval = et8ek8_get_frame_interval,
        .set_frame_interval = et8ek8_set_frame_interval,
};

static const struct v4l2_subdev_ops et8ek8_ops = {
        .core = &et8ek8_core_ops,
        .video = &et8ek8_video_ops,
        .pad = &et8ek8_pad_ops,
};

static const struct v4l2_subdev_internal_ops et8ek8_internal_ops = {
        .registered = et8ek8_registered,
        .open = et8ek8_open,
        .close = et8ek8_close,
};

/* --------------------------------------------------------------------------
 * I2C driver
 */
static int __maybe_unused et8ek8_suspend(struct device *dev)
{
        struct v4l2_subdev *subdev = dev_get_drvdata(dev);
        struct et8ek8_sensor *sensor = to_et8ek8_sensor(subdev);

        if (!sensor->power_count)
                return 0;

        return __et8ek8_set_power(sensor, false);
}

static int __maybe_unused et8ek8_resume(struct device *dev)
{
        struct v4l2_subdev *subdev = dev_get_drvdata(dev);
        struct et8ek8_sensor *sensor = to_et8ek8_sensor(subdev);

        if (!sensor->power_count)
                return 0;

        return __et8ek8_set_power(sensor, true);
}

static int et8ek8_probe(struct i2c_client *client)
{
        struct et8ek8_sensor *sensor;
        struct device *dev = &client->dev;
        int ret;

        sensor = devm_kzalloc(&client->dev, sizeof(*sensor), GFP_KERNEL);
        if (!sensor)
                return -ENOMEM;

        sensor->reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
        if (IS_ERR(sensor->reset)) {
                dev_dbg(&client->dev, "could not request reset gpio\n");
                return PTR_ERR(sensor->reset);
        }

        sensor->vana = devm_regulator_get(dev, "vana");
        if (IS_ERR(sensor->vana)) {
                dev_err(&client->dev, "could not get regulator for vana\n");
                return PTR_ERR(sensor->vana);
        }

        sensor->ext_clk = devm_v4l2_sensor_clk_get_legacy(dev, NULL, true,
                                                          9600000);
        if (IS_ERR(sensor->ext_clk))
                return dev_err_probe(&client->dev, PTR_ERR(sensor->ext_clk),
                                     "could not get clock\n");

        sensor->xclk_freq = clk_get_rate(sensor->ext_clk);

        mutex_init(&sensor->power_lock);

        v4l2_i2c_subdev_init(&sensor->subdev, client, &et8ek8_ops);
        sensor->subdev.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
        sensor->subdev.internal_ops = &et8ek8_internal_ops;

        sensor->subdev.entity.function = MEDIA_ENT_F_CAM_SENSOR;
        sensor->pad.flags = MEDIA_PAD_FL_SOURCE;
        ret = media_entity_pads_init(&sensor->subdev.entity, 1, &sensor->pad);
        if (ret < 0) {
                dev_err(&client->dev, "media entity init failed!\n");
                goto err_mutex;
        }

        ret = v4l2_async_register_subdev_sensor(&sensor->subdev);
        if (ret < 0)
                goto err_entity;

        dev_dbg(dev, "initialized!\n");

        return 0;

err_entity:
        media_entity_cleanup(&sensor->subdev.entity);
err_mutex:
        mutex_destroy(&sensor->power_lock);
        return ret;
}

static void et8ek8_remove(struct i2c_client *client)
{
        struct v4l2_subdev *subdev = i2c_get_clientdata(client);
        struct et8ek8_sensor *sensor = to_et8ek8_sensor(subdev);

        if (sensor->power_count) {
                WARN_ON(1);
                et8ek8_power_off(sensor);
                sensor->power_count = 0;
        }

        v4l2_device_unregister_subdev(&sensor->subdev);
        device_remove_file(&client->dev, &dev_attr_priv_mem);
        v4l2_ctrl_handler_free(&sensor->ctrl_handler);
        v4l2_async_unregister_subdev(&sensor->subdev);
        media_entity_cleanup(&sensor->subdev.entity);
        mutex_destroy(&sensor->power_lock);
}

static const struct of_device_id et8ek8_of_table[] = {
        { .compatible = "toshiba,et8ek8" },
        { },
};
MODULE_DEVICE_TABLE(of, et8ek8_of_table);

static const struct i2c_device_id et8ek8_id_table[] = {
        { ET8EK8_NAME },
        { }
};
MODULE_DEVICE_TABLE(i2c, et8ek8_id_table);

static const struct dev_pm_ops et8ek8_pm_ops = {
        SET_SYSTEM_SLEEP_PM_OPS(et8ek8_suspend, et8ek8_resume)
};

static struct i2c_driver et8ek8_i2c_driver = {
        .driver         = {
                .name   = ET8EK8_NAME,
                .pm     = &et8ek8_pm_ops,
                .of_match_table = et8ek8_of_table,
        },
        .probe          = et8ek8_probe,
        .remove         = et8ek8_remove,
        .id_table       = et8ek8_id_table,
};

module_i2c_driver(et8ek8_i2c_driver);

MODULE_AUTHOR("Sakari Ailus <sakari.ailus@iki.fi>, Pavel Machek <pavel@ucw.cz");
MODULE_DESCRIPTION("Toshiba ET8EK8 camera sensor driver");
MODULE_LICENSE("GPL");