// SPDX-License-Identifier: GPL-2.0
/*
 * imx274.c - IMX274 CMOS Image Sensor driver
 *
 * Copyright (C) 2017, Leopard Imaging, Inc.
 *
 * Leon Luo <leonl@leopardimaging.com>
 * Edwin Zou <edwinz@leopardimaging.com>
 * Luca Ceresoli <luca@lucaceresoli.net>
 */

#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/gpio.h>
#include <linux/gpio/consumer.h>
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of_gpio.h>
#include <linux/regmap.h>
#include <linux/slab.h>
#include <linux/v4l2-mediabus.h>
#include <linux/videodev2.h>

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

/*
 * See "SHR, SVR Setting" in datasheet
 */
#define IMX274_DEFAULT_FRAME_LENGTH             (4550)
#define IMX274_MAX_FRAME_LENGTH                 (0x000fffff)

/*
 * See "Frame Rate Adjustment" in datasheet
 */
#define IMX274_PIXCLK_CONST1                    (72000000)
#define IMX274_PIXCLK_CONST2                    (1000000)

/*
 * The input gain is shifted by IMX274_GAIN_SHIFT to get
 * decimal number. The real gain is
 * (float)input_gain_value / (1 << IMX274_GAIN_SHIFT)
 */
#define IMX274_GAIN_SHIFT                       (8)
#define IMX274_GAIN_SHIFT_MASK                  ((1 << IMX274_GAIN_SHIFT) - 1)

/*
 * See "Analog Gain" and "Digital Gain" in datasheet
 * min gain is 1X
 * max gain is calculated based on IMX274_GAIN_REG_MAX
 */
#define IMX274_GAIN_REG_MAX                     (1957)
#define IMX274_MIN_GAIN                         (0x01 << IMX274_GAIN_SHIFT)
#define IMX274_MAX_ANALOG_GAIN                  ((2048 << IMX274_GAIN_SHIFT)\
                                        / (2048 - IMX274_GAIN_REG_MAX))
#define IMX274_MAX_DIGITAL_GAIN                 (8)
#define IMX274_DEF_GAIN                         (20 << IMX274_GAIN_SHIFT)
#define IMX274_GAIN_CONST                       (2048) /* for gain formula */

/*
 * 1 line time in us = (HMAX / 72), minimal is 4 lines
 */
#define IMX274_MIN_EXPOSURE_TIME                (4 * 260 / 72)

#define IMX274_DEFAULT_BINNING                  IMX274_BINNING_OFF
#define IMX274_MAX_WIDTH                        (3840)
#define IMX274_MAX_HEIGHT                       (2160)
#define IMX274_MAX_FRAME_RATE                   (120)
#define IMX274_MIN_FRAME_RATE                   (5)
#define IMX274_DEF_FRAME_RATE                   (60)

/*
 * register SHR is limited to (SVR value + 1) x VMAX value - 4
 */
#define IMX274_SHR_LIMIT_CONST                  (4)

/*
 * Min and max sensor reset delay (microseconds)
 */
#define IMX274_RESET_DELAY1                     (2000)
#define IMX274_RESET_DELAY2                     (2200)

/*
 * shift and mask constants
 */
#define IMX274_SHIFT_8_BITS                     (8)
#define IMX274_SHIFT_16_BITS                    (16)
#define IMX274_MASK_LSB_2_BITS                  (0x03)
#define IMX274_MASK_LSB_3_BITS                  (0x07)
#define IMX274_MASK_LSB_4_BITS                  (0x0f)
#define IMX274_MASK_LSB_8_BITS                  (0x00ff)

#define DRIVER_NAME "IMX274"

/*
 * IMX274 register definitions
 */
#define IMX274_SHR_REG_MSB                      0x300D /* SHR */
#define IMX274_SHR_REG_LSB                      0x300C /* SHR */
#define IMX274_SVR_REG_MSB                      0x300F /* SVR */
#define IMX274_SVR_REG_LSB                      0x300E /* SVR */
#define IMX274_HTRIM_EN_REG                     0x3037
#define IMX274_HTRIM_START_REG_LSB              0x3038
#define IMX274_HTRIM_START_REG_MSB              0x3039
#define IMX274_HTRIM_END_REG_LSB                0x303A
#define IMX274_HTRIM_END_REG_MSB                0x303B
#define IMX274_VWIDCUTEN_REG                    0x30DD
#define IMX274_VWIDCUT_REG_LSB                  0x30DE
#define IMX274_VWIDCUT_REG_MSB                  0x30DF
#define IMX274_VWINPOS_REG_LSB                  0x30E0
#define IMX274_VWINPOS_REG_MSB                  0x30E1
#define IMX274_WRITE_VSIZE_REG_LSB              0x3130
#define IMX274_WRITE_VSIZE_REG_MSB              0x3131
#define IMX274_Y_OUT_SIZE_REG_LSB               0x3132
#define IMX274_Y_OUT_SIZE_REG_MSB               0x3133
#define IMX274_VMAX_REG_1                       0x30FA /* VMAX, MSB */
#define IMX274_VMAX_REG_2                       0x30F9 /* VMAX */
#define IMX274_VMAX_REG_3                       0x30F8 /* VMAX, LSB */
#define IMX274_HMAX_REG_MSB                     0x30F7 /* HMAX */
#define IMX274_HMAX_REG_LSB                     0x30F6 /* HMAX */
#define IMX274_ANALOG_GAIN_ADDR_LSB             0x300A /* ANALOG GAIN LSB */
#define IMX274_ANALOG_GAIN_ADDR_MSB             0x300B /* ANALOG GAIN MSB */
#define IMX274_DIGITAL_GAIN_REG                 0x3012 /* Digital Gain */
#define IMX274_VFLIP_REG                        0x301A /* VERTICAL FLIP */
#define IMX274_TEST_PATTERN_REG                 0x303D /* TEST PATTERN */
#define IMX274_STANDBY_REG                      0x3000 /* STANDBY */

#define IMX274_TABLE_WAIT_MS                    0
#define IMX274_TABLE_END                        1

/*
 * imx274 I2C operation related structure
 */
struct reg_8 {
        u16 addr;
        u8 val;
};

static const struct regmap_config imx274_regmap_config = {
        .reg_bits = 16,
        .val_bits = 8,
        .cache_type = REGCACHE_RBTREE,
};

enum imx274_binning {
        IMX274_BINNING_OFF,
        IMX274_BINNING_2_1,
        IMX274_BINNING_3_1,
};

/*
 * Parameters for each imx274 readout mode.
 *
 * These are the values to configure the sensor in one of the
 * implemented modes.
 *
 * @init_regs: registers to initialize the mode
 * @bin_ratio: downscale factor (e.g. 3 for 3:1 binning)
 * @min_frame_len: Minimum frame length for each mode (see "Frame Rate
 *                 Adjustment (CSI-2)" in the datasheet)
 * @min_SHR: Minimum SHR register value (see "Shutter Setting (CSI-2)" in the
 *           datasheet)
 * @max_fps: Maximum frames per second
 * @nocpiop: Number of clocks per internal offset period (see "Integration Time
 *           in Each Readout Drive Mode (CSI-2)" in the datasheet)
 */
struct imx274_mode {
        const struct reg_8 *init_regs;
        unsigned int bin_ratio;
        int min_frame_len;
        int min_SHR;
        int max_fps;
        int nocpiop;
};

/*
 * imx274 test pattern related structure
 */
enum {
        TEST_PATTERN_DISABLED = 0,
        TEST_PATTERN_ALL_000H,
        TEST_PATTERN_ALL_FFFH,
        TEST_PATTERN_ALL_555H,
        TEST_PATTERN_ALL_AAAH,
        TEST_PATTERN_VSP_5AH, /* VERTICAL STRIPE PATTERN 555H/AAAH */
        TEST_PATTERN_VSP_A5H, /* VERTICAL STRIPE PATTERN AAAH/555H */
        TEST_PATTERN_VSP_05H, /* VERTICAL STRIPE PATTERN 000H/555H */
        TEST_PATTERN_VSP_50H, /* VERTICAL STRIPE PATTERN 555H/000H */
        TEST_PATTERN_VSP_0FH, /* VERTICAL STRIPE PATTERN 000H/FFFH */
        TEST_PATTERN_VSP_F0H, /* VERTICAL STRIPE PATTERN FFFH/000H */
        TEST_PATTERN_H_COLOR_BARS,
        TEST_PATTERN_V_COLOR_BARS,
};

static const char * const tp_qmenu[] = {
        "Disabled",
        "All 000h Pattern",
        "All FFFh Pattern",
        "All 555h Pattern",
        "All AAAh Pattern",
        "Vertical Stripe (555h / AAAh)",
        "Vertical Stripe (AAAh / 555h)",
        "Vertical Stripe (000h / 555h)",
        "Vertical Stripe (555h / 000h)",
        "Vertical Stripe (000h / FFFh)",
        "Vertical Stripe (FFFh / 000h)",
        "Vertical Color Bars",
        "Horizontal Color Bars",
};

/*
 * All-pixel scan mode (10-bit)
 * imx274 mode1(refer to datasheet) register configuration with
 * 3840x2160 resolution, raw10 data and mipi four lane output
 */
static const struct reg_8 imx274_mode1_3840x2160_raw10[] = {
        {0x3004, 0x01},
        {0x3005, 0x01},
        {0x3006, 0x00},
        {0x3007, 0xa2},

        {0x3018, 0xA2}, /* output XVS, HVS */

        {0x306B, 0x05},
        {0x30E2, 0x01},

        {0x30EE, 0x01},
        {0x3342, 0x0A},
        {0x3343, 0x00},
        {0x3344, 0x16},
        {0x3345, 0x00},
        {0x33A6, 0x01},
        {0x3528, 0x0E},
        {0x3554, 0x1F},
        {0x3555, 0x01},
        {0x3556, 0x01},
        {0x3557, 0x01},
        {0x3558, 0x01},
        {0x3559, 0x00},
        {0x355A, 0x00},
        {0x35BA, 0x0E},
        {0x366A, 0x1B},
        {0x366B, 0x1A},
        {0x366C, 0x19},
        {0x366D, 0x17},
        {0x3A41, 0x08},

        {IMX274_TABLE_END, 0x00}
};

/*
 * Horizontal/vertical 2/2-line binning
 * (Horizontal and vertical weightedbinning, 10-bit)
 * imx274 mode3(refer to datasheet) register configuration with
 * 1920x1080 resolution, raw10 data and mipi four lane output
 */
static const struct reg_8 imx274_mode3_1920x1080_raw10[] = {
        {0x3004, 0x02},
        {0x3005, 0x21},
        {0x3006, 0x00},
        {0x3007, 0xb1},

        {0x3018, 0xA2}, /* output XVS, HVS */

        {0x306B, 0x05},
        {0x30E2, 0x02},

        {0x30EE, 0x01},
        {0x3342, 0x0A},
        {0x3343, 0x00},
        {0x3344, 0x1A},
        {0x3345, 0x00},
        {0x33A6, 0x01},
        {0x3528, 0x0E},
        {0x3554, 0x00},
        {0x3555, 0x01},
        {0x3556, 0x01},
        {0x3557, 0x01},
        {0x3558, 0x01},
        {0x3559, 0x00},
        {0x355A, 0x00},
        {0x35BA, 0x0E},
        {0x366A, 0x1B},
        {0x366B, 0x1A},
        {0x366C, 0x19},
        {0x366D, 0x17},
        {0x3A41, 0x08},

        {IMX274_TABLE_END, 0x00}
};

/*
 * Vertical 2/3 subsampling binning horizontal 3 binning
 * imx274 mode5(refer to datasheet) register configuration with
 * 1280x720 resolution, raw10 data and mipi four lane output
 */
static const struct reg_8 imx274_mode5_1280x720_raw10[] = {
        {0x3004, 0x03},
        {0x3005, 0x31},
        {0x3006, 0x00},
        {0x3007, 0xa9},

        {0x3018, 0xA2}, /* output XVS, HVS */

        {0x306B, 0x05},
        {0x30E2, 0x03},

        {0x30EE, 0x01},
        {0x3342, 0x0A},
        {0x3343, 0x00},
        {0x3344, 0x1B},
        {0x3345, 0x00},
        {0x33A6, 0x01},
        {0x3528, 0x0E},
        {0x3554, 0x00},
        {0x3555, 0x01},
        {0x3556, 0x01},
        {0x3557, 0x01},
        {0x3558, 0x01},
        {0x3559, 0x00},
        {0x355A, 0x00},
        {0x35BA, 0x0E},
        {0x366A, 0x1B},
        {0x366B, 0x19},
        {0x366C, 0x17},
        {0x366D, 0x17},
        {0x3A41, 0x04},

        {IMX274_TABLE_END, 0x00}
};

/*
 * imx274 first step register configuration for
 * starting stream
 */
static const struct reg_8 imx274_start_1[] = {
        {IMX274_STANDBY_REG, 0x12},

        /* PLRD: clock settings */
        {0x3120, 0xF0},
        {0x3121, 0x00},
        {0x3122, 0x02},
        {0x3129, 0x9C},
        {0x312A, 0x02},
        {0x312D, 0x02},

        {0x310B, 0x00},

        /* PLSTMG */
        {0x304C, 0x00}, /* PLSTMG01 */
        {0x304D, 0x03},
        {0x331C, 0x1A},
        {0x331D, 0x00},
        {0x3502, 0x02},
        {0x3529, 0x0E},
        {0x352A, 0x0E},
        {0x352B, 0x0E},
        {0x3538, 0x0E},
        {0x3539, 0x0E},
        {0x3553, 0x00},
        {0x357D, 0x05},
        {0x357F, 0x05},
        {0x3581, 0x04},
        {0x3583, 0x76},
        {0x3587, 0x01},
        {0x35BB, 0x0E},
        {0x35BC, 0x0E},
        {0x35BD, 0x0E},
        {0x35BE, 0x0E},
        {0x35BF, 0x0E},
        {0x366E, 0x00},
        {0x366F, 0x00},
        {0x3670, 0x00},
        {0x3671, 0x00},

        /* PSMIPI */
        {0x3304, 0x32}, /* PSMIPI1 */
        {0x3305, 0x00},
        {0x3306, 0x32},
        {0x3307, 0x00},
        {0x3590, 0x32},
        {0x3591, 0x00},
        {0x3686, 0x32},
        {0x3687, 0x00},

        {IMX274_TABLE_END, 0x00}
};

/*
 * imx274 second step register configuration for
 * starting stream
 */
static const struct reg_8 imx274_start_2[] = {
        {IMX274_STANDBY_REG, 0x00},
        {0x303E, 0x02}, /* SYS_MODE = 2 */
        {IMX274_TABLE_END, 0x00}
};

/*
 * imx274 third step register configuration for
 * starting stream
 */
static const struct reg_8 imx274_start_3[] = {
        {0x30F4, 0x00},
        {0x3018, 0xA2}, /* XHS VHS OUTPUT */
        {IMX274_TABLE_END, 0x00}
};

/*
 * imx274 register configuration for stopping stream
 */
static const struct reg_8 imx274_stop[] = {
        {IMX274_STANDBY_REG, 0x01},
        {IMX274_TABLE_END, 0x00}
};

/*
 * imx274 disable test pattern register configuration
 */
static const struct reg_8 imx274_tp_disabled[] = {
        {0x303C, 0x00},
        {0x377F, 0x00},
        {0x3781, 0x00},
        {0x370B, 0x00},
        {IMX274_TABLE_END, 0x00}
};

/*
 * imx274 test pattern register configuration
 * reg 0x303D defines the test pattern modes
 */
static const struct reg_8 imx274_tp_regs[] = {
        {0x303C, 0x11},
        {0x370E, 0x01},
        {0x377F, 0x01},
        {0x3781, 0x01},
        {0x370B, 0x11},
        {IMX274_TABLE_END, 0x00}
};

/* nocpiop happens to be the same number for the implemented modes */
static const struct imx274_mode imx274_modes[] = {
        {
                /* mode 1, 4K */
                .bin_ratio = 1,
                .init_regs = imx274_mode1_3840x2160_raw10,
                .min_frame_len = 4550,
                .min_SHR = 12,
                .max_fps = 60,
                .nocpiop = 112,
        },
        {
                /* mode 3, 1080p */
                .bin_ratio = 2,
                .init_regs = imx274_mode3_1920x1080_raw10,
                .min_frame_len = 2310,
                .min_SHR = 8,
                .max_fps = 120,
                .nocpiop = 112,
        },
        {
                /* mode 5, 720p */
                .bin_ratio = 3,
                .init_regs = imx274_mode5_1280x720_raw10,
                .min_frame_len = 2310,
                .min_SHR = 8,
                .max_fps = 120,
                .nocpiop = 112,
        },
};

/*
 * struct imx274_ctrls - imx274 ctrl structure
 * @handler: V4L2 ctrl handler structure
 * @exposure: Pointer to expsure ctrl structure
 * @gain: Pointer to gain ctrl structure
 * @vflip: Pointer to vflip ctrl structure
 * @test_pattern: Pointer to test pattern ctrl structure
 */
struct imx274_ctrls {
        struct v4l2_ctrl_handler handler;
        struct v4l2_ctrl *exposure;
        struct v4l2_ctrl *gain;
        struct v4l2_ctrl *vflip;
        struct v4l2_ctrl *test_pattern;
};

/*
 * struct stim274 - imx274 device structure
 * @sd: V4L2 subdevice structure
 * @pad: Media pad structure
 * @client: Pointer to I2C client
 * @ctrls: imx274 control structure
 * @crop: rect to be captured
 * @compose: compose rect, i.e. output resolution
 * @format: V4L2 media bus frame format structure
 *          (width and height are in sync with the compose rect)
 * @frame_rate: V4L2 frame rate structure
 * @regmap: Pointer to regmap structure
 * @reset_gpio: Pointer to reset gpio
 * @lock: Mutex structure
 * @mode: Parameters for the selected readout mode
 */
struct stimx274 {
        struct v4l2_subdev sd;
        struct media_pad pad;
        struct i2c_client *client;
        struct imx274_ctrls ctrls;
        struct v4l2_rect crop;
        struct v4l2_mbus_framefmt format;
        struct v4l2_fract frame_interval;
        struct regmap *regmap;
        struct gpio_desc *reset_gpio;
        struct mutex lock; /* mutex lock for operations */
        const struct imx274_mode *mode;
};

#define IMX274_ROUND(dim, step, flags)                  \
        ((flags) & V4L2_SEL_FLAG_GE                     \
         ? roundup((dim), (step))                       \
         : ((flags) & V4L2_SEL_FLAG_LE                  \
            ? rounddown((dim), (step))                  \
            : rounddown((dim) + (step) / 2, (step))))

/*
 * Function declaration
 */
static int imx274_set_gain(struct stimx274 *priv, struct v4l2_ctrl *ctrl);
static int imx274_set_exposure(struct stimx274 *priv, int val);
static int imx274_set_vflip(struct stimx274 *priv, int val);
static int imx274_set_test_pattern(struct stimx274 *priv, int val);
static int imx274_set_frame_interval(struct stimx274 *priv,
                                     struct v4l2_fract frame_interval);

static inline void msleep_range(unsigned int delay_base)
{
        usleep_range(delay_base * 1000, delay_base * 1000 + 500);
}

/*
 * v4l2_ctrl and v4l2_subdev related operations
 */
static inline struct v4l2_subdev *ctrl_to_sd(struct v4l2_ctrl *ctrl)
{
        return &container_of(ctrl->handler,
                             struct stimx274, ctrls.handler)->sd;
}

static inline struct stimx274 *to_imx274(struct v4l2_subdev *sd)
{
        return container_of(sd, struct stimx274, sd);
}

/*
 * Writing a register table
 *
 * @priv: Pointer to device
 * @table: Table containing register values (with optional delays)
 *
 * This is used to write register table into sensor's reg map.
 *
 * Return: 0 on success, errors otherwise
 */
static int imx274_write_table(struct stimx274 *priv, const struct reg_8 table[])
{
        struct regmap *regmap = priv->regmap;
        int err = 0;
        const struct reg_8 *next;
        u8 val;

        int range_start = -1;
        int range_count = 0;
        u8 range_vals[16];
        int max_range_vals = ARRAY_SIZE(range_vals);

        for (next = table;; next++) {
                if ((next->addr != range_start + range_count) ||
                    (next->addr == IMX274_TABLE_END) ||
                    (next->addr == IMX274_TABLE_WAIT_MS) ||
                    (range_count == max_range_vals)) {
                        if (range_count == 1)
                                err = regmap_write(regmap,
                                                   range_start, range_vals[0]);
                        else if (range_count > 1)
                                err = regmap_bulk_write(regmap, range_start,
                                                        &range_vals[0],
                                                        range_count);
                        else
                                err = 0;

                        if (err)
                                return err;

                        range_start = -1;
                        range_count = 0;

                        /* Handle special address values */
                        if (next->addr == IMX274_TABLE_END)
                                break;

                        if (next->addr == IMX274_TABLE_WAIT_MS) {
                                msleep_range(next->val);
                                continue;
                        }
                }

                val = next->val;

                if (range_start == -1)
                        range_start = next->addr;

                range_vals[range_count++] = val;
        }
        return 0;
}

static inline int imx274_write_reg(struct stimx274 *priv, u16 addr, u8 val)
{
        int err;

        err = regmap_write(priv->regmap, addr, val);
        if (err)
                dev_err(&priv->client->dev,
                        "%s : i2c write failed, %x = %x\n", __func__,
                        addr, val);
        else
                dev_dbg(&priv->client->dev,
                        "%s : addr 0x%x, val=0x%x\n", __func__,
                        addr, val);
        return err;
}

/**
 * Read a multibyte register.
 *
 * Uses a bulk read where possible.
 *
 * @priv: Pointer to device structure
 * @addr: Address of the LSB register.  Other registers must be
 *        consecutive, least-to-most significant.
 * @val: Pointer to store the register value (cpu endianness)
 * @nbytes: Number of bytes to read (range: [1..3]).
 *          Other bytes are zet to 0.
 *
 * Return: 0 on success, errors otherwise
 */
static int imx274_read_mbreg(struct stimx274 *priv, u16 addr, u32 *val,
                             size_t nbytes)
{
        __le32 val_le = 0;
        int err;

        err = regmap_bulk_read(priv->regmap, addr, &val_le, nbytes);
        if (err) {
                dev_err(&priv->client->dev,
                        "%s : i2c bulk read failed, %x (%zu bytes)\n",
                        __func__, addr, nbytes);
        } else {
                *val = le32_to_cpu(val_le);
                dev_dbg(&priv->client->dev,
                        "%s : addr 0x%x, val=0x%x (%zu bytes)\n",
                        __func__, addr, *val, nbytes);
        }

        return err;
}

/**
 * Write a multibyte register.
 *
 * Uses a bulk write where possible.
 *
 * @priv: Pointer to device structure
 * @addr: Address of the LSB register.  Other registers must be
 *        consecutive, least-to-most significant.
 * @val: Value to be written to the register (cpu endianness)
 * @nbytes: Number of bytes to write (range: [1..3])
 */
static int imx274_write_mbreg(struct stimx274 *priv, u16 addr, u32 val,
                              size_t nbytes)
{
        __le32 val_le = cpu_to_le32(val);
        int err;

        err = regmap_bulk_write(priv->regmap, addr, &val_le, nbytes);
        if (err)
                dev_err(&priv->client->dev,
                        "%s : i2c bulk write failed, %x = %x (%zu bytes)\n",
                        __func__, addr, val, nbytes);
        else
                dev_dbg(&priv->client->dev,
                        "%s : addr 0x%x, val=0x%x (%zu bytes)\n",
                        __func__, addr, val, nbytes);
        return err;
}

/*
 * Set mode registers to start stream.
 * @priv: Pointer to device structure
 *
 * Return: 0 on success, errors otherwise
 */
static int imx274_mode_regs(struct stimx274 *priv)
{
        int err = 0;

        err = imx274_write_table(priv, imx274_start_1);
        if (err)
                return err;

        err = imx274_write_table(priv, priv->mode->init_regs);

        return err;
}

/*
 * imx274_start_stream - Function for starting stream per mode index
 * @priv: Pointer to device structure
 *
 * Return: 0 on success, errors otherwise
 */
static int imx274_start_stream(struct stimx274 *priv)
{
        int err = 0;

        /*
         * Refer to "Standby Cancel Sequence when using CSI-2" in
         * imx274 datasheet, it should wait 10ms or more here.
         * give it 1 extra ms for margin
         */
        msleep_range(11);
        err = imx274_write_table(priv, imx274_start_2);
        if (err)
                return err;

        /*
         * Refer to "Standby Cancel Sequence when using CSI-2" in
         * imx274 datasheet, it should wait 7ms or more here.
         * give it 1 extra ms for margin
         */
        msleep_range(8);
        err = imx274_write_table(priv, imx274_start_3);
        if (err)
                return err;

        return 0;
}

/*
 * imx274_reset - Function called to reset the sensor
 * @priv: Pointer to device structure
 * @rst: Input value for determining the sensor's end state after reset
 *
 * Set the senor in reset and then
 * if rst = 0, keep it in reset;
 * if rst = 1, bring it out of reset.
 *
 */
static void imx274_reset(struct stimx274 *priv, int rst)
{
        gpiod_set_value_cansleep(priv->reset_gpio, 0);
        usleep_range(IMX274_RESET_DELAY1, IMX274_RESET_DELAY2);
        gpiod_set_value_cansleep(priv->reset_gpio, !!rst);
        usleep_range(IMX274_RESET_DELAY1, IMX274_RESET_DELAY2);
}

/**
 * imx274_s_ctrl - This is used to set the imx274 V4L2 controls
 * @ctrl: V4L2 control to be set
 *
 * This function is used to set the V4L2 controls for the imx274 sensor.
 *
 * Return: 0 on success, errors otherwise
 */
static int imx274_s_ctrl(struct v4l2_ctrl *ctrl)
{
        struct v4l2_subdev *sd = ctrl_to_sd(ctrl);
        struct stimx274 *imx274 = to_imx274(sd);
        int ret = -EINVAL;

        dev_dbg(&imx274->client->dev,
                "%s : s_ctrl: %s, value: %d\n", __func__,
                ctrl->name, ctrl->val);

        switch (ctrl->id) {
        case V4L2_CID_EXPOSURE:
                dev_dbg(&imx274->client->dev,
                        "%s : set V4L2_CID_EXPOSURE\n", __func__);
                ret = imx274_set_exposure(imx274, ctrl->val);
                break;

        case V4L2_CID_GAIN:
                dev_dbg(&imx274->client->dev,
                        "%s : set V4L2_CID_GAIN\n", __func__);
                ret = imx274_set_gain(imx274, ctrl);
                break;

        case V4L2_CID_VFLIP:
                dev_dbg(&imx274->client->dev,
                        "%s : set V4L2_CID_VFLIP\n", __func__);
                ret = imx274_set_vflip(imx274, ctrl->val);
                break;

        case V4L2_CID_TEST_PATTERN:
                dev_dbg(&imx274->client->dev,
                        "%s : set V4L2_CID_TEST_PATTERN\n", __func__);
                ret = imx274_set_test_pattern(imx274, ctrl->val);
                break;
        }

        return ret;
}

static int imx274_binning_goodness(struct stimx274 *imx274,
                                   int w, int ask_w,
                                   int h, int ask_h, u32 flags)
{
        struct device *dev = &imx274->client->dev;
        const int goodness = 100000;
        int val = 0;

        if (flags & V4L2_SEL_FLAG_GE) {
                if (w < ask_w)
                        val -= goodness;
                if (h < ask_h)
                        val -= goodness;
        }

        if (flags & V4L2_SEL_FLAG_LE) {
                if (w > ask_w)
                        val -= goodness;
                if (h > ask_h)
                        val -= goodness;
        }

        val -= abs(w - ask_w);
        val -= abs(h - ask_h);

        dev_dbg(dev, "%s: ask %dx%d, size %dx%d, goodness %d\n",
                __func__, ask_w, ask_h, w, h, val);

        return val;
}

/**
 * Helper function to change binning and set both compose and format.
 *
 * We have two entry points to change binning: set_fmt and
 * set_selection(COMPOSE). Both have to compute the new output size
 * and set it in both the compose rect and the frame format size. We
 * also need to do the same things after setting cropping to restore
 * 1:1 binning.
 *
 * This function contains the common code for these three cases, it
 * has many arguments in order to accommodate the needs of all of
 * them.
 *
 * Must be called with imx274->lock locked.
 *
 * @imx274: The device object
 * @cfg:    The pad config we are editing for TRY requests
 * @which:  V4L2_SUBDEV_FORMAT_ACTIVE or V4L2_SUBDEV_FORMAT_TRY from the caller
 * @width:  Input-output parameter: set to the desired width before
 *          the call, contains the chosen value after returning successfully
 * @height: Input-output parameter for height (see @width)
 * @flags:  Selection flags from struct v4l2_subdev_selection, or 0 if not
 *          available (when called from set_fmt)
 */
static int __imx274_change_compose(struct stimx274 *imx274,
                                   struct v4l2_subdev_pad_config *cfg,
                                   u32 which,
                                   u32 *width,
                                   u32 *height,
                                   u32 flags)
{
        struct device *dev = &imx274->client->dev;
        const struct v4l2_rect *cur_crop;
        struct v4l2_mbus_framefmt *tgt_fmt;
        unsigned int i;
        const struct imx274_mode *best_mode = &imx274_modes[0];
        int best_goodness = INT_MIN;

        if (which == V4L2_SUBDEV_FORMAT_TRY) {
                cur_crop = &cfg->try_crop;
                tgt_fmt = &cfg->try_fmt;
        } else {
                cur_crop = &imx274->crop;
                tgt_fmt = &imx274->format;
        }

        for (i = 0; i < ARRAY_SIZE(imx274_modes); i++) {
                unsigned int ratio = imx274_modes[i].bin_ratio;

                int goodness = imx274_binning_goodness(
                        imx274,
                        cur_crop->width / ratio, *width,
                        cur_crop->height / ratio, *height,
                        flags);

                if (goodness >= best_goodness) {
                        best_goodness = goodness;
                        best_mode = &imx274_modes[i];
                }
        }

        *width = cur_crop->width / best_mode->bin_ratio;
        *height = cur_crop->height / best_mode->bin_ratio;

        if (which == V4L2_SUBDEV_FORMAT_ACTIVE)
                imx274->mode = best_mode;

        dev_dbg(dev, "%s: selected %u:1 binning\n",
                __func__, best_mode->bin_ratio);

        tgt_fmt->width = *width;
        tgt_fmt->height = *height;
        tgt_fmt->field = V4L2_FIELD_NONE;

        return 0;
}

/**
 * imx274_get_fmt - Get the pad format
 * @sd: Pointer to V4L2 Sub device structure
 * @cfg: Pointer to sub device pad information structure
 * @fmt: Pointer to pad level media bus format
 *
 * This function is used to get the pad format information.
 *
 * Return: 0 on success
 */
static int imx274_get_fmt(struct v4l2_subdev *sd,
                          struct v4l2_subdev_pad_config *cfg,
                          struct v4l2_subdev_format *fmt)
{
        struct stimx274 *imx274 = to_imx274(sd);

        mutex_lock(&imx274->lock);
        fmt->format = imx274->format;
        mutex_unlock(&imx274->lock);
        return 0;
}

/**
 * imx274_set_fmt - This is used to set the pad format
 * @sd: Pointer to V4L2 Sub device structure
 * @cfg: Pointer to sub device pad information structure
 * @format: Pointer to pad level media bus format
 *
 * This function is used to set the pad format.
 *
 * Return: 0 on success
 */
static int imx274_set_fmt(struct v4l2_subdev *sd,
                          struct v4l2_subdev_pad_config *cfg,
                          struct v4l2_subdev_format *format)
{
        struct v4l2_mbus_framefmt *fmt = &format->format;
        struct stimx274 *imx274 = to_imx274(sd);
        int err = 0;

        mutex_lock(&imx274->lock);

        err = __imx274_change_compose(imx274, cfg, format->which,
                                      &fmt->width, &fmt->height, 0);

        if (err)
                goto out;

        /*
         * __imx274_change_compose already set width and height in the
         * applicable format, but we need to keep all other format
         * values, so do a full copy here
         */
        fmt->field = V4L2_FIELD_NONE;
        if (format->which == V4L2_SUBDEV_FORMAT_TRY)
                cfg->try_fmt = *fmt;
        else
                imx274->format = *fmt;

out:
        mutex_unlock(&imx274->lock);

        return err;
}

static int imx274_get_selection(struct v4l2_subdev *sd,
                                struct v4l2_subdev_pad_config *cfg,
                                struct v4l2_subdev_selection *sel)
{
        struct stimx274 *imx274 = to_imx274(sd);
        const struct v4l2_rect *src_crop;
        const struct v4l2_mbus_framefmt *src_fmt;
        int ret = 0;

        if (sel->pad != 0)
                return -EINVAL;

        if (sel->target == V4L2_SEL_TGT_CROP_BOUNDS) {
                sel->r.left = 0;
                sel->r.top = 0;
                sel->r.width = IMX274_MAX_WIDTH;
                sel->r.height = IMX274_MAX_HEIGHT;
                return 0;
        }

        if (sel->which == V4L2_SUBDEV_FORMAT_TRY) {
                src_crop = &cfg->try_crop;
                src_fmt = &cfg->try_fmt;
        } else {
                src_crop = &imx274->crop;
                src_fmt = &imx274->format;
        }

        mutex_lock(&imx274->lock);

        switch (sel->target) {
        case V4L2_SEL_TGT_CROP:
                sel->r = *src_crop;
                break;
        case V4L2_SEL_TGT_COMPOSE_BOUNDS:
                sel->r.top = 0;
                sel->r.left = 0;
                sel->r.width = src_crop->width;
                sel->r.height = src_crop->height;
                break;
        case V4L2_SEL_TGT_COMPOSE:
                sel->r.top = 0;
                sel->r.left = 0;
                sel->r.width = src_fmt->width;
                sel->r.height = src_fmt->height;
                break;
        default:
                ret = -EINVAL;
        }

        mutex_unlock(&imx274->lock);

        return ret;
}

static int imx274_set_selection_crop(struct stimx274 *imx274,
                                     struct v4l2_subdev_pad_config *cfg,
                                     struct v4l2_subdev_selection *sel)
{
        struct v4l2_rect *tgt_crop;
        struct v4l2_rect new_crop;
        bool size_changed;

        /*
         * h_step could be 12 or 24 depending on the binning. But we
         * won't know the binning until we choose the mode later in
         * __imx274_change_compose(). Thus let's be safe and use the
         * most conservative value in all cases.
         */
        const u32 h_step = 24;

        new_crop.width = min_t(u32,
                               IMX274_ROUND(sel->r.width, h_step, sel->flags),
                               IMX274_MAX_WIDTH);

        /* Constraint: HTRIMMING_END - HTRIMMING_START >= 144 */
        if (new_crop.width < 144)
                new_crop.width = 144;

        new_crop.left = min_t(u32,
                              IMX274_ROUND(sel->r.left, h_step, 0),
                              IMX274_MAX_WIDTH - new_crop.width);

        new_crop.height = min_t(u32,
                                IMX274_ROUND(sel->r.height, 2, sel->flags),
                                IMX274_MAX_HEIGHT);

        new_crop.top = min_t(u32, IMX274_ROUND(sel->r.top, 2, 0),
                             IMX274_MAX_HEIGHT - new_crop.height);

        sel->r = new_crop;

        if (sel->which == V4L2_SUBDEV_FORMAT_TRY)
                tgt_crop = &cfg->try_crop;
        else
                tgt_crop = &imx274->crop;

        mutex_lock(&imx274->lock);

        size_changed = (new_crop.width != tgt_crop->width ||
                        new_crop.height != tgt_crop->height);

        /* __imx274_change_compose needs the new size in *tgt_crop */
        *tgt_crop = new_crop;

        /* if crop size changed then reset the output image size */
        if (size_changed)
                __imx274_change_compose(imx274, cfg, sel->which,
                                        &new_crop.width, &new_crop.height,
                                        sel->flags);

        mutex_unlock(&imx274->lock);

        return 0;
}

static int imx274_set_selection(struct v4l2_subdev *sd,
                                struct v4l2_subdev_pad_config *cfg,
                                struct v4l2_subdev_selection *sel)
{
        struct stimx274 *imx274 = to_imx274(sd);

        if (sel->pad != 0)
                return -EINVAL;

        if (sel->target == V4L2_SEL_TGT_CROP)
                return imx274_set_selection_crop(imx274, cfg, sel);

        if (sel->target == V4L2_SEL_TGT_COMPOSE) {
                int err;

                mutex_lock(&imx274->lock);
                err =  __imx274_change_compose(imx274, cfg, sel->which,
                                               &sel->r.width, &sel->r.height,
                                               sel->flags);
                mutex_unlock(&imx274->lock);

                /*
                 * __imx274_change_compose already set width and
                 * height in set->r, we still need to set top-left
                 */
                if (!err) {
                        sel->r.top = 0;
                        sel->r.left = 0;
                }

                return err;
        }

        return -EINVAL;
}

static int imx274_apply_trimming(struct stimx274 *imx274)
{
        u32 h_start;
        u32 h_end;
        u32 hmax;
        u32 v_cut;
        s32 v_pos;
        u32 write_v_size;
        u32 y_out_size;
        int err;

        h_start = imx274->crop.left + 12;
        h_end = h_start + imx274->crop.width;

        /* Use the minimum allowed value of HMAX */
        /* Note: except in mode 1, (width / 16 + 23) is always < hmax_min */
        /* Note: 260 is the minimum HMAX in all implemented modes */
        hmax = max_t(u32, 260, (imx274->crop.width) / 16 + 23);

        /* invert v_pos if VFLIP */
        v_pos = imx274->ctrls.vflip->cur.val ?
                (-imx274->crop.top / 2) : (imx274->crop.top / 2);
        v_cut = (IMX274_MAX_HEIGHT - imx274->crop.height) / 2;
        write_v_size = imx274->crop.height + 22;
        y_out_size   = imx274->crop.height + 14;

        err = imx274_write_mbreg(imx274, IMX274_HMAX_REG_LSB, hmax, 2);
        if (!err)
                err = imx274_write_mbreg(imx274, IMX274_HTRIM_EN_REG, 1, 1);
        if (!err)
                err = imx274_write_mbreg(imx274, IMX274_HTRIM_START_REG_LSB,
                                         h_start, 2);
        if (!err)
                err = imx274_write_mbreg(imx274, IMX274_HTRIM_END_REG_LSB,
                                         h_end, 2);
        if (!err)
                err = imx274_write_mbreg(imx274, IMX274_VWIDCUTEN_REG, 1, 1);
        if (!err)
                err = imx274_write_mbreg(imx274, IMX274_VWIDCUT_REG_LSB,
                                         v_cut, 2);
        if (!err)
                err = imx274_write_mbreg(imx274, IMX274_VWINPOS_REG_LSB,
                                         v_pos, 2);
        if (!err)
                err = imx274_write_mbreg(imx274, IMX274_WRITE_VSIZE_REG_LSB,
                                         write_v_size, 2);
        if (!err)
                err = imx274_write_mbreg(imx274, IMX274_Y_OUT_SIZE_REG_LSB,
                                         y_out_size, 2);

        return err;
}

/**
 * imx274_g_frame_interval - Get the frame interval
 * @sd: Pointer to V4L2 Sub device structure
 * @fi: Pointer to V4l2 Sub device frame interval structure
 *
 * This function is used to get the frame interval.
 *
 * Return: 0 on success
 */
static int imx274_g_frame_interval(struct v4l2_subdev *sd,
                                   struct v4l2_subdev_frame_interval *fi)
{
        struct stimx274 *imx274 = to_imx274(sd);

        fi->interval = imx274->frame_interval;
        dev_dbg(&imx274->client->dev, "%s frame rate = %d / %d\n",
                __func__, imx274->frame_interval.numerator,
                imx274->frame_interval.denominator);

        return 0;
}

/**
 * imx274_s_frame_interval - Set the frame interval
 * @sd: Pointer to V4L2 Sub device structure
 * @fi: Pointer to V4l2 Sub device frame interval structure
 *
 * This function is used to set the frame intervavl.
 *
 * Return: 0 on success
 */
static int imx274_s_frame_interval(struct v4l2_subdev *sd,
                                   struct v4l2_subdev_frame_interval *fi)
{
        struct stimx274 *imx274 = to_imx274(sd);
        struct v4l2_ctrl *ctrl = imx274->ctrls.exposure;
        int min, max, def;
        int ret;

        mutex_lock(&imx274->lock);
        ret = imx274_set_frame_interval(imx274, fi->interval);

        if (!ret) {
                fi->interval = imx274->frame_interval;

                /*
                 * exposure time range is decided by frame interval
                 * need to update it after frame interval changes
                 */
                min = IMX274_MIN_EXPOSURE_TIME;
                max = fi->interval.numerator * 1000000
                        / fi->interval.denominator;
                def = max;
                if (__v4l2_ctrl_modify_range(ctrl, min, max, 1, def)) {
                        dev_err(&imx274->client->dev,
                                "Exposure ctrl range update failed\n");
                        goto unlock;
                }

                /* update exposure time accordingly */
                imx274_set_exposure(imx274, ctrl->val);

                dev_dbg(&imx274->client->dev, "set frame interval to %uus\n",
                        fi->interval.numerator * 1000000
                        / fi->interval.denominator);
        }

unlock:
        mutex_unlock(&imx274->lock);

        return ret;
}

/**
 * imx274_load_default - load default control values
 * @priv: Pointer to device structure
 *
 * Return: 0 on success, errors otherwise
 */
static int imx274_load_default(struct stimx274 *priv)
{
        int ret;

        /* load default control values */
        priv->frame_interval.numerator = 1;
        priv->frame_interval.denominator = IMX274_DEF_FRAME_RATE;
        priv->ctrls.exposure->val = 1000000 / IMX274_DEF_FRAME_RATE;
        priv->ctrls.gain->val = IMX274_DEF_GAIN;
        priv->ctrls.vflip->val = 0;
        priv->ctrls.test_pattern->val = TEST_PATTERN_DISABLED;

        /* update frame rate */
        ret = imx274_set_frame_interval(priv,
                                        priv->frame_interval);
        if (ret)
                return ret;

        /* update exposure time */
        ret = v4l2_ctrl_s_ctrl(priv->ctrls.exposure, priv->ctrls.exposure->val);
        if (ret)
                return ret;

        /* update gain */
        ret = v4l2_ctrl_s_ctrl(priv->ctrls.gain, priv->ctrls.gain->val);
        if (ret)
                return ret;

        /* update vflip */
        ret = v4l2_ctrl_s_ctrl(priv->ctrls.vflip, priv->ctrls.vflip->val);
        if (ret)
                return ret;

        return 0;
}

/**
 * imx274_s_stream - It is used to start/stop the streaming.
 * @sd: V4L2 Sub device
 * @on: Flag (True / False)
 *
 * This function controls the start or stop of streaming for the
 * imx274 sensor.
 *
 * Return: 0 on success, errors otherwise
 */
static int imx274_s_stream(struct v4l2_subdev *sd, int on)
{
        struct stimx274 *imx274 = to_imx274(sd);
        int ret = 0;

        dev_dbg(&imx274->client->dev, "%s : %s, mode index = %td\n", __func__,
                on ? "Stream Start" : "Stream Stop",
                imx274->mode - &imx274_modes[0]);

        mutex_lock(&imx274->lock);

        if (on) {
                /* load mode registers */
                ret = imx274_mode_regs(imx274);
                if (ret)
                        goto fail;

                ret = imx274_apply_trimming(imx274);
                if (ret)
                        goto fail;

                /*
                 * update frame rate & expsoure. if the last mode is different,
                 * HMAX could be changed. As the result, frame rate & exposure
                 * are changed.
                 * gain is not affected.
                 */
                ret = imx274_set_frame_interval(imx274,
                                                imx274->frame_interval);
                if (ret)
                        goto fail;

                /* update exposure time */
                ret = __v4l2_ctrl_s_ctrl(imx274->ctrls.exposure,
                                         imx274->ctrls.exposure->val);
                if (ret)
                        goto fail;

                /* start stream */
                ret = imx274_start_stream(imx274);
                if (ret)
                        goto fail;
        } else {
                /* stop stream */
                ret = imx274_write_table(imx274, imx274_stop);
                if (ret)
                        goto fail;
        }

        mutex_unlock(&imx274->lock);
        dev_dbg(&imx274->client->dev, "%s : Done\n", __func__);
        return 0;

fail:
        mutex_unlock(&imx274->lock);
        dev_err(&imx274->client->dev, "s_stream failed\n");
        return ret;
}

/*
 * imx274_get_frame_length - Function for obtaining current frame length
 * @priv: Pointer to device structure
 * @val: Pointer to obainted value
 *
 * frame_length = vmax x (svr + 1), in unit of hmax.
 *
 * Return: 0 on success
 */
static int imx274_get_frame_length(struct stimx274 *priv, u32 *val)
{
        int err;
        u32 svr;
        u32 vmax;

        err = imx274_read_mbreg(priv, IMX274_SVR_REG_LSB, &svr, 2);
        if (err)
                goto fail;

        err = imx274_read_mbreg(priv, IMX274_VMAX_REG_3, &vmax, 3);
        if (err)
                goto fail;

        *val = vmax * (svr + 1);

        return 0;

fail:
        dev_err(&priv->client->dev, "%s error = %d\n", __func__, err);
        return err;
}

static int imx274_clamp_coarse_time(struct stimx274 *priv, u32 *val,
                                    u32 *frame_length)
{
        int err;

        err = imx274_get_frame_length(priv, frame_length);
        if (err)
                return err;

        if (*frame_length < priv->mode->min_frame_len)
                *frame_length =  priv->mode->min_frame_len;

        *val = *frame_length - *val; /* convert to raw shr */
        if (*val > *frame_length - IMX274_SHR_LIMIT_CONST)
                *val = *frame_length - IMX274_SHR_LIMIT_CONST;
        else if (*val < priv->mode->min_SHR)
                *val = priv->mode->min_SHR;

        return 0;
}

/*
 * imx274_set_digital gain - Function called when setting digital gain
 * @priv: Pointer to device structure
 * @dgain: Value of digital gain.
 *
 * Digital gain has only 4 steps: 1x, 2x, 4x, and 8x
 *
 * Return: 0 on success
 */
static int imx274_set_digital_gain(struct stimx274 *priv, u32 dgain)
{
        u8 reg_val;

        reg_val = ffs(dgain);

        if (reg_val)
                reg_val--;

        reg_val = clamp(reg_val, (u8)0, (u8)3);

        return imx274_write_reg(priv, IMX274_DIGITAL_GAIN_REG,
                                reg_val & IMX274_MASK_LSB_4_BITS);
}

/*
 * imx274_set_gain - Function called when setting gain
 * @priv: Pointer to device structure
 * @val: Value of gain. the real value = val << IMX274_GAIN_SHIFT;
 * @ctrl: v4l2 control pointer
 *
 * Set the gain based on input value.
 * The caller should hold the mutex lock imx274->lock if necessary
 *
 * Return: 0 on success
 */
static int imx274_set_gain(struct stimx274 *priv, struct v4l2_ctrl *ctrl)
{
        int err;
        u32 gain, analog_gain, digital_gain, gain_reg;

        gain = (u32)(ctrl->val);

        dev_dbg(&priv->client->dev,
                "%s : input gain = %d.%d\n", __func__,
                gain >> IMX274_GAIN_SHIFT,
                ((gain & IMX274_GAIN_SHIFT_MASK) * 100) >> IMX274_GAIN_SHIFT);

        if (gain > IMX274_MAX_DIGITAL_GAIN * IMX274_MAX_ANALOG_GAIN)
                gain = IMX274_MAX_DIGITAL_GAIN * IMX274_MAX_ANALOG_GAIN;
        else if (gain < IMX274_MIN_GAIN)
                gain = IMX274_MIN_GAIN;

        if (gain <= IMX274_MAX_ANALOG_GAIN)
                digital_gain = 1;
        else if (gain <= IMX274_MAX_ANALOG_GAIN * 2)
                digital_gain = 2;
        else if (gain <= IMX274_MAX_ANALOG_GAIN * 4)
                digital_gain = 4;
        else
                digital_gain = IMX274_MAX_DIGITAL_GAIN;

        analog_gain = gain / digital_gain;

        dev_dbg(&priv->client->dev,
                "%s : digital gain = %d, analog gain = %d.%d\n",
                __func__, digital_gain, analog_gain >> IMX274_GAIN_SHIFT,
                ((analog_gain & IMX274_GAIN_SHIFT_MASK) * 100)
                >> IMX274_GAIN_SHIFT);

        err = imx274_set_digital_gain(priv, digital_gain);
        if (err)
                goto fail;

        /* convert to register value, refer to imx274 datasheet */
        gain_reg = (u32)IMX274_GAIN_CONST -
                (IMX274_GAIN_CONST << IMX274_GAIN_SHIFT) / analog_gain;
        if (gain_reg > IMX274_GAIN_REG_MAX)
                gain_reg = IMX274_GAIN_REG_MAX;

        err = imx274_write_mbreg(priv, IMX274_ANALOG_GAIN_ADDR_LSB, gain_reg,
                                 2);
        if (err)
                goto fail;

        if (IMX274_GAIN_CONST - gain_reg == 0) {
                err = -EINVAL;
                goto fail;
        }

        /* convert register value back to gain value */
        ctrl->val = (IMX274_GAIN_CONST << IMX274_GAIN_SHIFT)
                        / (IMX274_GAIN_CONST - gain_reg) * digital_gain;

        dev_dbg(&priv->client->dev,
                "%s : GAIN control success, gain_reg = %d, new gain = %d\n",
                __func__, gain_reg, ctrl->val);

        return 0;

fail:
        dev_err(&priv->client->dev, "%s error = %d\n", __func__, err);
        return err;
}

/*
 * imx274_set_coarse_time - Function called when setting SHR value
 * @priv: Pointer to device structure
 * @val: Value for exposure time in number of line_length, or [HMAX]
 *
 * Set SHR value based on input value.
 *
 * Return: 0 on success
 */
static int imx274_set_coarse_time(struct stimx274 *priv, u32 *val)
{
        int err;
        u32 coarse_time, frame_length;

        coarse_time = *val;

        /* convert exposure_time to appropriate SHR value */
        err = imx274_clamp_coarse_time(priv, &coarse_time, &frame_length);
        if (err)
                goto fail;

        err = imx274_write_mbreg(priv, IMX274_SHR_REG_LSB, coarse_time, 2);
        if (err)
                goto fail;

        *val = frame_length - coarse_time;
        return 0;

fail:
        dev_err(&priv->client->dev, "%s error = %d\n", __func__, err);
        return err;
}

/*
 * imx274_set_exposure - Function called when setting exposure time
 * @priv: Pointer to device structure
 * @val: Variable for exposure time, in the unit of micro-second
 *
 * Set exposure time based on input value.
 * The caller should hold the mutex lock imx274->lock if necessary
 *
 * Return: 0 on success
 */
static int imx274_set_exposure(struct stimx274 *priv, int val)
{
        int err;
        u32 hmax;
        u32 coarse_time; /* exposure time in unit of line (HMAX)*/

        dev_dbg(&priv->client->dev,
                "%s : EXPOSURE control input = %d\n", __func__, val);

        /* step 1: convert input exposure_time (val) into number of 1[HMAX] */

        err = imx274_read_mbreg(priv, IMX274_HMAX_REG_LSB, &hmax, 2);
        if (err)
                goto fail;

        if (hmax == 0) {
                err = -EINVAL;
                goto fail;
        }

        coarse_time = (IMX274_PIXCLK_CONST1 / IMX274_PIXCLK_CONST2 * val
                        - priv->mode->nocpiop) / hmax;

        /* step 2: convert exposure_time into SHR value */

        /* set SHR */
        err = imx274_set_coarse_time(priv, &coarse_time);
        if (err)
                goto fail;

        priv->ctrls.exposure->val =
                        (coarse_time * hmax + priv->mode->nocpiop)
                        / (IMX274_PIXCLK_CONST1 / IMX274_PIXCLK_CONST2);

        dev_dbg(&priv->client->dev,
                "%s : EXPOSURE control success\n", __func__);
        return 0;

fail:
        dev_err(&priv->client->dev, "%s error = %d\n", __func__, err);

        return err;
}

/*
 * imx274_set_vflip - Function called when setting vertical flip
 * @priv: Pointer to device structure
 * @val: Value for vflip setting
 *
 * Set vertical flip based on input value.
 * val = 0: normal, no vertical flip
 * val = 1: vertical flip enabled
 * The caller should hold the mutex lock imx274->lock if necessary
 *
 * Return: 0 on success
 */
static int imx274_set_vflip(struct stimx274 *priv, int val)
{
        int err;

        err = imx274_write_reg(priv, IMX274_VFLIP_REG, val);
        if (err) {
                dev_err(&priv->client->dev, "VFLIP control error\n");
                return err;
        }

        dev_dbg(&priv->client->dev,
                "%s : VFLIP control success\n", __func__);

        return 0;
}

/*
 * imx274_set_test_pattern - Function called when setting test pattern
 * @priv: Pointer to device structure
 * @val: Variable for test pattern
 *
 * Set to different test patterns based on input value.
 *
 * Return: 0 on success
 */
static int imx274_set_test_pattern(struct stimx274 *priv, int val)
{
        int err = 0;

        if (val == TEST_PATTERN_DISABLED) {
                err = imx274_write_table(priv, imx274_tp_disabled);
        } else if (val <= TEST_PATTERN_V_COLOR_BARS) {
                err = imx274_write_reg(priv, IMX274_TEST_PATTERN_REG, val - 1);
                if (!err)
                        err = imx274_write_table(priv, imx274_tp_regs);
        } else {
                err = -EINVAL;
        }

        if (!err)
                dev_dbg(&priv->client->dev,
                        "%s : TEST PATTERN control success\n", __func__);
        else
                dev_err(&priv->client->dev, "%s error = %d\n", __func__, err);

        return err;
}

/*
 * imx274_set_frame_length - Function called when setting frame length
 * @priv: Pointer to device structure
 * @val: Variable for frame length (= VMAX, i.e. vertical drive period length)
 *
 * Set frame length based on input value.
 *
 * Return: 0 on success
 */
static int imx274_set_frame_length(struct stimx274 *priv, u32 val)
{
        int err;
        u32 frame_length;

        dev_dbg(&priv->client->dev, "%s : input length = %d\n",
                __func__, val);

        frame_length = (u32)val;

        err = imx274_write_mbreg(priv, IMX274_VMAX_REG_3, frame_length, 3);
        if (err)
                goto fail;

        return 0;

fail:
        dev_err(&priv->client->dev, "%s error = %d\n", __func__, err);
        return err;
}

/*
 * imx274_set_frame_interval - Function called when setting frame interval
 * @priv: Pointer to device structure
 * @frame_interval: Variable for frame interval
 *
 * Change frame interval by updating VMAX value
 * The caller should hold the mutex lock imx274->lock if necessary
 *
 * Return: 0 on success
 */
static int imx274_set_frame_interval(struct stimx274 *priv,
                                     struct v4l2_fract frame_interval)
{
        int err;
        u32 frame_length, req_frame_rate;
        u32 svr;
        u32 hmax;

        dev_dbg(&priv->client->dev, "%s: input frame interval = %d / %d",
                __func__, frame_interval.numerator,
                frame_interval.denominator);

        if (frame_interval.numerator == 0 || frame_interval.denominator == 0) {
                frame_interval.denominator = IMX274_DEF_FRAME_RATE;
                frame_interval.numerator = 1;
        }

        req_frame_rate = (u32)(frame_interval.denominator
                                / frame_interval.numerator);

        /* boundary check */
        if (req_frame_rate > priv->mode->max_fps) {
                frame_interval.numerator = 1;
                frame_interval.denominator = priv->mode->max_fps;
        } else if (req_frame_rate < IMX274_MIN_FRAME_RATE) {
                frame_interval.numerator = 1;
                frame_interval.denominator = IMX274_MIN_FRAME_RATE;
        }

        /*
         * VMAX = 1/frame_rate x 72M / (SVR+1) / HMAX
         * frame_length (i.e. VMAX) = (frame_interval) x 72M /(SVR+1) / HMAX
         */

        err = imx274_read_mbreg(priv, IMX274_SVR_REG_LSB, &svr, 2);
        if (err)
                goto fail;

        dev_dbg(&priv->client->dev,
                "%s : register SVR = %d\n", __func__, svr);

        err = imx274_read_mbreg(priv, IMX274_HMAX_REG_LSB, &hmax, 2);
        if (err)
                goto fail;

        dev_dbg(&priv->client->dev,
                "%s : register HMAX = %d\n", __func__, hmax);

        if (hmax == 0 || frame_interval.denominator == 0) {
                err = -EINVAL;
                goto fail;
        }

        frame_length = IMX274_PIXCLK_CONST1 / (svr + 1) / hmax
                                        * frame_interval.numerator
                                        / frame_interval.denominator;

        err = imx274_set_frame_length(priv, frame_length);
        if (err)
                goto fail;

        priv->frame_interval = frame_interval;
        return 0;

fail:
        dev_err(&priv->client->dev, "%s error = %d\n", __func__, err);
        return err;
}

static const struct v4l2_subdev_pad_ops imx274_pad_ops = {
        .get_fmt = imx274_get_fmt,
        .set_fmt = imx274_set_fmt,
        .get_selection = imx274_get_selection,
        .set_selection = imx274_set_selection,
};

static const struct v4l2_subdev_video_ops imx274_video_ops = {
        .g_frame_interval = imx274_g_frame_interval,
        .s_frame_interval = imx274_s_frame_interval,
        .s_stream = imx274_s_stream,
};

static const struct v4l2_subdev_ops imx274_subdev_ops = {
        .pad = &imx274_pad_ops,
        .video = &imx274_video_ops,
};

static const struct v4l2_ctrl_ops imx274_ctrl_ops = {
        .s_ctrl = imx274_s_ctrl,
};

static const struct of_device_id imx274_of_id_table[] = {
        { .compatible = "sony,imx274" },
        { }
};
MODULE_DEVICE_TABLE(of, imx274_of_id_table);

static const struct i2c_device_id imx274_id[] = {
        { "IMX274", 0 },
        { }
};
MODULE_DEVICE_TABLE(i2c, imx274_id);

static int imx274_probe(struct i2c_client *client)
{
        struct v4l2_subdev *sd;
        struct stimx274 *imx274;
        int ret;

        /* initialize imx274 */
        imx274 = devm_kzalloc(&client->dev, sizeof(*imx274), GFP_KERNEL);
        if (!imx274)
                return -ENOMEM;

        mutex_init(&imx274->lock);

        /* initialize format */
        imx274->mode = &imx274_modes[IMX274_DEFAULT_BINNING];
        imx274->crop.width = IMX274_MAX_WIDTH;
        imx274->crop.height = IMX274_MAX_HEIGHT;
        imx274->format.width = imx274->crop.width / imx274->mode->bin_ratio;
        imx274->format.height = imx274->crop.height / imx274->mode->bin_ratio;
        imx274->format.field = V4L2_FIELD_NONE;
        imx274->format.code = MEDIA_BUS_FMT_SRGGB10_1X10;
        imx274->format.colorspace = V4L2_COLORSPACE_SRGB;
        imx274->frame_interval.numerator = 1;
        imx274->frame_interval.denominator = IMX274_DEF_FRAME_RATE;

        /* initialize regmap */
        imx274->regmap = devm_regmap_init_i2c(client, &imx274_regmap_config);
        if (IS_ERR(imx274->regmap)) {
                dev_err(&client->dev,
                        "regmap init failed: %ld\n", PTR_ERR(imx274->regmap));
                ret = -ENODEV;
                goto err_regmap;
        }

        /* initialize subdevice */
        imx274->client = client;
        sd = &imx274->sd;
        v4l2_i2c_subdev_init(sd, client, &imx274_subdev_ops);
        sd->flags |= V4L2_SUBDEV_FL_HAS_DEVNODE | V4L2_SUBDEV_FL_HAS_EVENTS;

        /* initialize subdev media pad */
        imx274->pad.flags = MEDIA_PAD_FL_SOURCE;
        sd->entity.function = MEDIA_ENT_F_CAM_SENSOR;
        ret = media_entity_pads_init(&sd->entity, 1, &imx274->pad);
        if (ret < 0) {
                dev_err(&client->dev,
                        "%s : media entity init Failed %d\n", __func__, ret);
                goto err_regmap;
        }

        /* initialize sensor reset gpio */
        imx274->reset_gpio = devm_gpiod_get_optional(&client->dev, "reset",
                                                     GPIOD_OUT_HIGH);
        if (IS_ERR(imx274->reset_gpio)) {
                if (PTR_ERR(imx274->reset_gpio) != -EPROBE_DEFER)
                        dev_err(&client->dev, "Reset GPIO not setup in DT");
                ret = PTR_ERR(imx274->reset_gpio);
                goto err_me;
        }

        /* pull sensor out of reset */
        imx274_reset(imx274, 1);

        /* initialize controls */
        ret = v4l2_ctrl_handler_init(&imx274->ctrls.handler, 4);
        if (ret < 0) {
                dev_err(&client->dev,
                        "%s : ctrl handler init Failed\n", __func__);
                goto err_me;
        }

        imx274->ctrls.handler.lock = &imx274->lock;

        /* add new controls */
        imx274->ctrls.test_pattern = v4l2_ctrl_new_std_menu_items(
                &imx274->ctrls.handler, &imx274_ctrl_ops,
                V4L2_CID_TEST_PATTERN,
                ARRAY_SIZE(tp_qmenu) - 1, 0, 0, tp_qmenu);

        imx274->ctrls.gain = v4l2_ctrl_new_std(
                &imx274->ctrls.handler,
                &imx274_ctrl_ops,
                V4L2_CID_GAIN, IMX274_MIN_GAIN,
                IMX274_MAX_DIGITAL_GAIN * IMX274_MAX_ANALOG_GAIN, 1,
                IMX274_DEF_GAIN);

        imx274->ctrls.exposure = v4l2_ctrl_new_std(
                &imx274->ctrls.handler,
                &imx274_ctrl_ops,
                V4L2_CID_EXPOSURE, IMX274_MIN_EXPOSURE_TIME,
                1000000 / IMX274_DEF_FRAME_RATE, 1,
                IMX274_MIN_EXPOSURE_TIME);

        imx274->ctrls.vflip = v4l2_ctrl_new_std(
                &imx274->ctrls.handler,
                &imx274_ctrl_ops,
                V4L2_CID_VFLIP, 0, 1, 1, 0);

        imx274->sd.ctrl_handler = &imx274->ctrls.handler;
        if (imx274->ctrls.handler.error) {
                ret = imx274->ctrls.handler.error;
                goto err_ctrls;
        }

        /* setup default controls */
        ret = v4l2_ctrl_handler_setup(&imx274->ctrls.handler);
        if (ret) {
                dev_err(&client->dev,
                        "Error %d setup default controls\n", ret);
                goto err_ctrls;
        }

        /* load default control values */
        ret = imx274_load_default(imx274);
        if (ret) {
                dev_err(&client->dev,
                        "%s : imx274_load_default failed %d\n",
                        __func__, ret);
                goto err_ctrls;
        }

        /* register subdevice */
        ret = v4l2_async_register_subdev(sd);
        if (ret < 0) {
                dev_err(&client->dev,
                        "%s : v4l2_async_register_subdev failed %d\n",
                        __func__, ret);
                goto err_ctrls;
        }

        dev_info(&client->dev, "imx274 : imx274 probe success !\n");
        return 0;

err_ctrls:
        v4l2_ctrl_handler_free(&imx274->ctrls.handler);
err_me:
        media_entity_cleanup(&sd->entity);
err_regmap:
        mutex_destroy(&imx274->lock);
        return ret;
}

static int imx274_remove(struct i2c_client *client)
{
        struct v4l2_subdev *sd = i2c_get_clientdata(client);
        struct stimx274 *imx274 = to_imx274(sd);

        /* stop stream */
        imx274_write_table(imx274, imx274_stop);

        v4l2_async_unregister_subdev(sd);
        v4l2_ctrl_handler_free(&imx274->ctrls.handler);
        media_entity_cleanup(&sd->entity);
        mutex_destroy(&imx274->lock);
        return 0;
}

static struct i2c_driver imx274_i2c_driver = {
        .driver = {
                .name   = DRIVER_NAME,
                .of_match_table = imx274_of_id_table,
        },
        .probe_new      = imx274_probe,
        .remove         = imx274_remove,
        .id_table       = imx274_id,
};

module_i2c_driver(imx274_i2c_driver);

MODULE_AUTHOR("Leon Luo <leonl@leopardimaging.com>");
MODULE_DESCRIPTION("IMX274 CMOS Image Sensor driver");
MODULE_LICENSE("GPL v2");