text: // 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/pm_runtime.h>
  #include <linux/regmap.h>
  #include <linux/regulator/consumer.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_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
  
  /* regulator supplies */
  static const char * const imx274_supply_names[] = {
  	"vddl",  /* IF (1.2V) supply */
  	"vdig",  /* Digital Core (1.8V) supply */
  	"vana",  /* Analog (2.8V) supply */
  };
  
  #define IMX274_NUM_SUPPLIES ARRAY_SIZE(imx274_supply_names)
  
  /*
   * 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,
  };
  
  /*
   * 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
   * @wbin_ratio: width downscale factor (e.g. 3 for 1280; 3 = 3840/1280)
   * @hbin_ratio: height downscale factor (e.g. 3 for 720; 3 = 2160/720)
   * @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;
  	u8 wbin_ratio;
  	u8 hbin_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}
  };
  
  /*
   * Vertical 2/8 subsampling horizontal 3 binning
   * imx274 mode6(refer to datasheet) register configuration with
   * 1280x540 resolution, raw10 data and mipi four lane output
   */
  static const struct reg_8 imx274_mode6_1280x540_raw10[] = {
  	{0x3004, 0x04}, /* mode setting */
  	{0x3005, 0x31},
  	{0x3006, 0x00},
  	{0x3007, 0x02}, /* mode setting */
  
  	{0x3018, 0xA2}, /* output XVS, HVS */
  
  	{0x306B, 0x05},
  	{0x30E2, 0x04}, /* mode setting */
  
  	{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, 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 */
  		.wbin_ratio = 1, /* 3840 */
  		.hbin_ratio = 1, /* 2160 */
  		.init_regs = imx274_mode1_3840x2160_raw10,
  		.min_frame_len = 4550,
  		.min_SHR = 12,
  		.max_fps = 60,
  		.nocpiop = 112,
  	},
  	{
  		/* mode 3, 1080p */
  		.wbin_ratio = 2, /* 1920 */
  		.hbin_ratio = 2, /* 1080 */
  		.init_regs = imx274_mode3_1920x1080_raw10,
  		.min_frame_len = 2310,
  		.min_SHR = 8,
  		.max_fps = 120,
  		.nocpiop = 112,
  	},
  	{
  		/* mode 5, 720p */
  		.wbin_ratio = 3, /* 1280 */
  		.hbin_ratio = 3, /* 720 */
  		.init_regs = imx274_mode5_1280x720_raw10,
  		.min_frame_len = 2310,
  		.min_SHR = 8,
  		.max_fps = 120,
  		.nocpiop = 112,
  	},
  	{
  		/* mode 6, 540p */
  		.wbin_ratio = 3, /* 1280 */
  		.hbin_ratio = 4, /* 540 */
  		.init_regs = imx274_mode6_1280x540_raw10,
  		.min_frame_len = 2310,
  		.min_SHR = 4,
  		.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
   * @supplies: List of analog and digital supply regulators
   * @inck: Pointer to sensor input clock
   * @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 regulator_bulk_data supplies[IMX274_NUM_SUPPLIES];
  	struct clk *inck;
  	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;
  }
  
  /**
   * imx274_read_mbreg - 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;
  }
  
  /**
   * imx274_write_mbreg - 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;
  
  	err = __v4l2_ctrl_handler_setup(&priv->ctrls.handler);
  	if (err) {
  		dev_err(&priv->client->dev, "Error %d setup controls\n", err);
  		return err;
  	}
  
  	/*
  	 * 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);
  }
  
  static int imx274_power_on(struct device *dev)
  {
  	struct i2c_client *client = to_i2c_client(dev);
  	struct v4l2_subdev *sd = i2c_get_clientdata(client);
  	struct stimx274 *imx274 = to_imx274(sd);
  	int ret;
  
  	/* keep sensor in reset before power on */
  	imx274_reset(imx274, 0);
  
  	ret = clk_prepare_enable(imx274->inck);
  	if (ret) {
  		dev_err(&imx274->client->dev,
  			"Failed to enable input clock: %d\n", ret);
  		return ret;
  	}
  
  	ret = regulator_bulk_enable(IMX274_NUM_SUPPLIES, imx274->supplies);
  	if (ret) {
  		dev_err(&imx274->client->dev,
  			"Failed to enable regulators: %d\n", ret);
  		goto fail_reg;
  	}
  
  	udelay(2);
  	imx274_reset(imx274, 1);
  
  	return 0;
  
  fail_reg:
  	clk_disable_unprepare(imx274->inck);
  	return ret;
  }
  
  static int imx274_power_off(struct device *dev)
  {
  	struct i2c_client *client = to_i2c_client(dev);
  	struct v4l2_subdev *sd = i2c_get_clientdata(client);
  	struct stimx274 *imx274 = to_imx274(sd);
  
  	imx274_reset(imx274, 0);
  
  	regulator_bulk_disable(IMX274_NUM_SUPPLIES, imx274->supplies);
  
  	clk_disable_unprepare(imx274->inck);
  
  	return 0;
  }
  
  static int imx274_regulators_get(struct device *dev, struct stimx274 *imx274)
  {
  	unsigned int i;
  
  	for (i = 0; i < IMX274_NUM_SUPPLIES; i++)
  		imx274->supplies[i].supply = imx274_supply_names[i];
  
  	return devm_regulator_bulk_get(dev, IMX274_NUM_SUPPLIES,
  					imx274->supplies);
  }
  
  /**
   * 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;
  
  	if (!pm_runtime_get_if_in_use(&imx274->client->dev))
  		return 0;
  
  	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;
  	}
  
  	pm_runtime_put(&imx274->client->dev);
  
  	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;
  }
  
  /**
   * __imx274_change_compose - 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++) {
  		u8 wratio = imx274_modes[i].wbin_ratio;
  		u8 hratio = imx274_modes[i].hbin_ratio;
  
  		int goodness = imx274_binning_goodness(
  			imx274,
  			cur_crop->width / wratio, *width,
  			cur_crop->height / hratio, *height,
  			flags);
  
  		if (goodness >= best_goodness) {
  			best_goodness = goodness;
  			best_mode = &imx274_modes[i];
  		}
  	}
  
  	*width = cur_crop->width / best_mode->wbin_ratio;
  	*height = cur_crop->height / best_mode->hbin_ratio;
  
  	if (which == V4L2_SUBDEV_FORMAT_ACTIVE)
  		imx274->mode = best_mode;
  
  	dev_dbg(dev, "%s: selected %ux%u binning\n",
  		__func__, best_mode->wbin_ratio, best_mode->hbin_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;
  
  	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;
  		ret = __v4l2_ctrl_modify_range(ctrl, min, max, 1, def);
  		if (ret) {
  			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 void imx274_load_default(struct stimx274 *priv)
  {
  	/* 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;
  }
  
  /**
   * 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) {
  		ret = pm_runtime_get_sync(&imx274->client->dev);
  		if (ret < 0) {
  			pm_runtime_put_noidle(&imx274->client->dev);
  			mutex_unlock(&imx274->lock);
  			return ret;
  		}
  
  		/* 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;
  
  		/* 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;
  
  		pm_runtime_put(&imx274->client->dev);
  	}
  
  	mutex_unlock(&imx274->lock);
  	dev_dbg(&imx274->client->dev, "%s : Done\n", __func__);
  	return 0;
  
  fail:
  	pm_runtime_put(&imx274->client->dev);
  	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);
  
  	imx274->inck = devm_clk_get_optional(&client->dev, "inck");
  	if (IS_ERR(imx274->inck))
  		return PTR_ERR(imx274->inck);
  
  	ret = imx274_regulators_get(&client->dev, imx274);
  	if (ret) {
  		dev_err(&client->dev,
  			"Failed to get power regulators, err: %d\n", ret);
  		return ret;
  	}
  
  	/* initialize format */
  	imx274->mode = &imx274_modes[0];
  	imx274->crop.width = IMX274_MAX_WIDTH;
  	imx274->crop.height = IMX274_MAX_HEIGHT;
  	imx274->format.width = imx274->crop.width / imx274->mode->wbin_ratio;
  	imx274->format.height = imx274->crop.height / imx274->mode->hbin_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;
  	}
  
  	/* power on the sensor */
  	ret = imx274_power_on(&client->dev);
  	if (ret < 0) {
  		dev_err(&client->dev,
  			"%s : imx274 power on failed\n", __func__);
  		goto err_me;
  	}
  
  	/* 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_power_off;
  	}
  
  	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;
  	}
  
  	/* load default control values */
  	imx274_load_default(imx274);
  
  	/* 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;
  	}
  
  	pm_runtime_set_active(&client->dev);
  	pm_runtime_enable(&client->dev);
  	pm_runtime_idle(&client->dev);
  
  	dev_info(&client->dev, "imx274 : imx274 probe success !\n");
  	return 0;
  
  err_ctrls:
  	v4l2_ctrl_handler_free(&imx274->ctrls.handler);
  err_power_off:
  	imx274_power_off(&client->dev);
  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);
  
  	pm_runtime_disable(&client->dev);
  	if (!pm_runtime_status_suspended(&client->dev))
  		imx274_power_off(&client->dev);
  	pm_runtime_set_suspended(&client->dev);
  
  	v4l2_async_unregister_subdev(sd);
  	v4l2_ctrl_handler_free(&imx274->ctrls.handler);
  
  	media_entity_cleanup(&sd->entity);
  	mutex_destroy(&imx274->lock);
  	return 0;
  }
  
  static const struct dev_pm_ops imx274_pm_ops = {
  	SET_RUNTIME_PM_OPS(imx274_power_off, imx274_power_on, NULL)
  };
  
  static struct i2c_driver imx274_i2c_driver = {
  	.driver = {
  		.name	= DRIVER_NAME,
  		.pm = &imx274_pm_ops,
  		.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");
  