media: imx274: V4l2 driver for Sony imx274 CMOS sensor

The imx274 is a Sony CMOS image sensor that has 1/2.5 image size.
It supports up to 3840x2160 (4K) 60fps, 1080p 120fps. The interface
is 4-lane MIPI CSI-2 running at 1.44Gbps each.

This driver has been tested on Xilinx ZCU102 platform with a Leopard
LI-IMX274MIPI-FMC camera board.

Support for the following features:
-Resolutions: 3840x2160, 1920x1080, 1280x720
-Frame rate: 3840x2160 : 5 – 60fps
            1920x1080 : 5 – 120fps
            1280x720 : 5 – 120fps
-Exposure time: 16 – (frame interval) micro-seconds
-Gain: 1x - 180x
-VFLIP: enable/disabledrivers/media/i2c/imx274.c
-Test pattern: 12 test patterns

Signed-off-by: Leon Luo <leonl@leopardimaging.com>
Tested-by: Sören Brinkmann <soren.brinkmann@xilinx.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

3 files changed, 1820 insertions, 0 deletions

diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
index 47113774a297..3c6d6428f525 100644
--- a/drivers/media/i2c/Kconfig
+++ b/drivers/media/i2c/Kconfig
@@ -555,6 +555,14 @@ config VIDEO_APTINA_PLL
 config VIDEO_SMIAPP_PLL
 	tristate
 
+config VIDEO_IMX274
+	tristate "Sony IMX274 sensor support"
+	depends on I2C && VIDEO_V4L2 && VIDEO_V4L2_SUBDEV_API
+	depends on MEDIA_CAMERA_SUPPORT
+	---help---
+	  This is a V4L2 sensor-level driver for the Sony IMX274
+	  CMOS image sensor.
+
 config VIDEO_OV2640
 	tristate "OmniVision OV2640 sensor support"
 	depends on VIDEO_V4L2 && I2C
diff --git a/drivers/media/i2c/Makefile b/drivers/media/i2c/Makefile
index c843c181dfb9..f8d57e453936 100644
--- a/drivers/media/i2c/Makefile
+++ b/drivers/media/i2c/Makefile
@@ -92,5 +92,6 @@ obj-$(CONFIG_VIDEO_IR_I2C)  += ir-kbd-i2c.o
 obj-$(CONFIG_VIDEO_ML86V7667)	+= ml86v7667.o
 obj-$(CONFIG_VIDEO_OV2659)	+= ov2659.o
 obj-$(CONFIG_VIDEO_TC358743)	+= tc358743.o
+obj-$(CONFIG_VIDEO_IMX274)	+= imx274.o
 
 obj-$(CONFIG_SDR_MAX2175) += max2175.o
diff --git a/drivers/media/i2c/imx274.c b/drivers/media/i2c/imx274.c
new file mode 100644
index 000000000000..ab6a5f31da74
--- /dev/null
+++ b/drivers/media/i2c/imx274.c
@@ -0,0 +1,1811 @@
+/*
+ * imx274.c - IMX274 CMOS Image Sensor driver
+ *
+ * Copyright (C) 2017, Leopard Imaging, Inc.
+ *
+ * Leon Luo <leonl@leopardimaging.com>
+ * Edwin Zou <edwinz@leopardimaging.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#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/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_MODE			IMX274_MODE_3840X2160
+#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)
+
+/*
+ * Constants for sensor reset delay
+ */
+#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_FRAME_LENGTH_ADDR_1		0x30FA /* VMAX, MSB */
+#define IMX274_FRAME_LENGTH_ADDR_2		0x30F9 /* VMAX */
+#define IMX274_FRAME_LENGTH_ADDR_3		0x30F8 /* VMAX, LSB */
+#define IMX274_SVR_REG_MSB			0x300F /* SVR */
+#define IMX274_SVR_REG_LSB			0x300E /* SVR */
+#define IMX274_HMAX_REG_MSB			0x30F7 /* HMAX */
+#define IMX274_HMAX_REG_LSB			0x30F6 /* HMAX */
+#define IMX274_COARSE_TIME_ADDR_MSB		0x300D /* SHR */
+#define IMX274_COARSE_TIME_ADDR_LSB		0x300C /* SHR */
+#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_mode {
+	IMX274_MODE_3840X2160,
+	IMX274_MODE_1920X1080,
+	IMX274_MODE_1280X720,
+
+	IMX274_MODE_START_STREAM_1,
+	IMX274_MODE_START_STREAM_2,
+	IMX274_MODE_START_STREAM_3,
+	IMX274_MODE_START_STREAM_4,
+	IMX274_MODE_STOP_STREAM
+};
+
+/*
+ * imx274 format related structure
+ */
+struct imx274_frmfmt {
+	u32 mbus_code;
+	enum v4l2_colorspace colorspace;
+	struct v4l2_frmsize_discrete size;
+	enum imx274_mode mode;
+};
+
+/*
+ * 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)",
+	"Horizontal Color Bars",
+	"Vertical 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, 0x02},
+
+	{0x3018, 0xA2}, /* output XVS, HVS */
+
+	{0x306B, 0x05},
+	{0x30E2, 0x01},
+	{0x30F6, 0x07}, /* HMAX, 263 */
+	{0x30F7, 0x01}, /* HMAX */
+
+	{0x30dd, 0x01}, /* crop to 2160 */
+	{0x30de, 0x06},
+	{0x30df, 0x00},
+	{0x30e0, 0x12},
+	{0x30e1, 0x00},
+	{0x3037, 0x01}, /* to crop to 3840 */
+	{0x3038, 0x0c},
+	{0x3039, 0x00},
+	{0x303a, 0x0c},
+	{0x303b, 0x0f},
+
+	{0x30EE, 0x01},
+	{0x3130, 0x86},
+	{0x3131, 0x08},
+	{0x3132, 0x7E},
+	{0x3133, 0x08},
+	{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, 0x11},
+
+	{0x3018, 0xA2}, /* output XVS, HVS */
+
+	{0x306B, 0x05},
+	{0x30E2, 0x02},
+
+	{0x30F6, 0x04}, /* HMAX, 260 */
+	{0x30F7, 0x01}, /* HMAX */
+
+	{0x30dd, 0x01}, /* to crop to 1920x1080 */
+	{0x30de, 0x05},
+	{0x30df, 0x00},
+	{0x30e0, 0x04},
+	{0x30e1, 0x00},
+	{0x3037, 0x01},
+	{0x3038, 0x0c},
+	{0x3039, 0x00},
+	{0x303a, 0x0c},
+	{0x303b, 0x0f},
+
+	{0x30EE, 0x01},
+	{0x3130, 0x4E},
+	{0x3131, 0x04},
+	{0x3132, 0x46},
+	{0x3133, 0x04},
+	{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, 0x09},
+
+	{0x3018, 0xA2}, /* output XVS, HVS */
+
+	{0x306B, 0x05},
+	{0x30E2, 0x03},
+
+	{0x30F6, 0x04}, /* HMAX, 260 */
+	{0x30F7, 0x01}, /* HMAX */
+
+	{0x30DD, 0x01},
+	{0x30DE, 0x07},
+	{0x30DF, 0x00},
+	{0x40E0, 0x04},
+	{0x30E1, 0x00},
+	{0x3030, 0xD4},
+	{0x3031, 0x02},
+	{0x3032, 0xD0},
+	{0x3033, 0x02},
+
+	{0x30EE, 0x01},
+	{0x3130, 0xE2},
+	{0x3131, 0x02},
+	{0x3132, 0xDE},
+	{0x3133, 0x02},
+	{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},
+	{IMX274_TABLE_END, 0x00}
+};
+
+/*
+ * imx274 second step register configuration for
+ * starting stream
+ */
+static const struct reg_8 imx274_start_2[] = {
+	{0x3120, 0xF0}, /* clock settings */
+	{0x3121, 0x00}, /* clock settings */
+	{0x3122, 0x02}, /* clock settings */
+	{0x3129, 0x9C}, /* clock settings */
+	{0x312A, 0x02}, /* clock settings */
+	{0x312D, 0x02}, /* clock settings */
+
+	{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 third step register configuration for
+ * starting stream
+ */
+static const struct reg_8 imx274_start_3[] = {
+	{IMX274_STANDBY_REG, 0x00},
+	{0x303E, 0x02}, /* SYS_MODE = 2 */
+	{IMX274_TABLE_END, 0x00}
+};
+
+/*
+ * imx274 forth step register configuration for
+ * starting stream
+ */
+static const struct reg_8 imx274_start_4[] = {
+	{0x30F4, 0x00},
+	{0x3018, 0xA2}, /* XHS VHS OUTUPT */
+	{IMX274_TABLE_END, 0x00}
+};
+
+/*
+ * imx274 register configuration for stoping 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}
+};
+
+static const struct reg_8 *mode_table[] = {
+	[IMX274_MODE_3840X2160]		= imx274_mode1_3840x2160_raw10,
+	[IMX274_MODE_1920X1080]		= imx274_mode3_1920x1080_raw10,
+	[IMX274_MODE_1280X720]		= imx274_mode5_1280x720_raw10,
+
+	[IMX274_MODE_START_STREAM_1]	= imx274_start_1,
+	[IMX274_MODE_START_STREAM_2]	= imx274_start_2,
+	[IMX274_MODE_START_STREAM_3]	= imx274_start_3,
+	[IMX274_MODE_START_STREAM_4]	= imx274_start_4,
+	[IMX274_MODE_STOP_STREAM]	= imx274_stop,
+};
+
+/*
+ * imx274 format related structure
+ */
+static const struct imx274_frmfmt imx274_formats[] = {
+	{MEDIA_BUS_FMT_SRGGB10_1X10, V4L2_COLORSPACE_SRGB, {3840, 2160},
+		IMX274_MODE_3840X2160},
+	{MEDIA_BUS_FMT_SRGGB10_1X10, V4L2_COLORSPACE_SRGB, {1920, 1080},
+		IMX274_MODE_1920X1080},
+	{MEDIA_BUS_FMT_SRGGB10_1X10, V4L2_COLORSPACE_SRGB, {1280, 720},
+		IMX274_MODE_1280X720},
+};
+
+/*
+ * minimal frame length for each mode
+ * refer to datasheet section "Frame Rate Adjustment (CSI-2)"
+ */
+static const int min_frame_len[] = {
+	4550, /* mode 1, 4K */
+	2310, /* mode 3, 1080p */
+	2310 /* mode 5, 720p */
+};
+
+/*
+ * minimal numbers of SHR register
+ * refer to datasheet table "Shutter Setting (CSI-2)"
+ */
+static const int min_SHR[] = {
+	12, /* mode 1, 4K */
+	8, /* mode 3, 1080p */
+	8 /* mode 5, 720p */
+};
+
+static const int max_frame_rate[] = {
+	60, /* mode 1 , 4K */
+	120, /* mode 3, 1080p */
+	120 /* mode 5, 720p */
+};
+
+/*
+ * Number of clocks per internal offset period
+ * a constant based on mode
+ * refer to section "Integration Time in Each Readout Drive Mode (CSI-2)"
+ * in the datasheet
+ * for the implemented 3 modes, it happens to be the same number
+ */
+static const int nocpiop[] = {
+	112, /* mode 1 , 4K */
+	112, /* mode 3, 1080p */
+	112 /* mode 5, 720p */
+};
+
+/*
+ * 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
+ * @pd: Media pad structure
+ * @client: Pointer to I2C client
+ * @ctrls: imx274 control structure
+ * @format: V4L2 media bus frame format structure
+ * @frame_rate: V4L2 frame rate structure
+ * @regmap: Pointer to regmap structure
+ * @reset_gpio: Pointer to reset gpio
+ * @lock: Mutex structure
+ * @mode_index: Resolution mode index
+ */
+struct stimx274 {
+	struct v4l2_subdev sd;
+	struct media_pad pad;
+	struct i2c_client *client;
+	struct imx274_ctrls ctrls;
+	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 */
+	u32 mode_index;
+};
+
+/*
+ * 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);
+}
+
+/*
+ * imx274_regmap_util_write_table_8 - Function for writing register table
+ * @regmap: Pointer to device reg map structure
+ * @table: Table containing register values
+ * @wait_ms_addr: Flag for performing delay
+ * @end_addr: Flag for incating end of table
+ *
+ * This is used to write register table into sensor's reg map.
+ *
+ * Return: 0 on success, errors otherwise
+ */
+static int imx274_regmap_util_write_table_8(struct regmap *regmap,
+					    const struct reg_8 table[],
+					    u16 wait_ms_addr, u16 end_addr)
+{
+	int err;
+	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 == end_addr) ||
+		    (next->addr == wait_ms_addr) ||
+		    (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);
+
+			if (err)
+				return err;
+
+			range_start = -1;
+			range_count = 0;
+
+			/* Handle special address values */
+			if (next->addr == end_addr)
+				break;
+
+			if (next->addr == wait_ms_addr) {
+				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_read_reg(struct stimx274 *priv, u16 addr, u8 *val)
+{
+	int err;
+
+	err = regmap_read(priv->regmap, addr, (unsigned int *)val);
+	if (err)
+		dev_err(&priv->client->dev,
+			"%s : i2c read failed, addr = %x\n", __func__, addr);
+	else
+		dev_dbg(&priv->client->dev,
+			"%s : addr 0x%x, val=0x%x\n", __func__,
+			addr, *val);
+	return err;
+}
+
+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;
+}
+
+static int imx274_write_table(struct stimx274 *priv, const struct reg_8 table[])
+{
+	return imx274_regmap_util_write_table_8(priv->regmap,
+		table, IMX274_TABLE_WAIT_MS, IMX274_TABLE_END);
+}
+
+/*
+ * imx274_mode_regs - Function for set mode registers per mode index
+ * @priv: Pointer to device structure
+ * @mode: Mode index value
+ *
+ * This is used to start steam per mode index.
+ * mode = 0, start stream for sensor Mode 1: 4K/raw10
+ * mode = 1, start stream for sensor Mode 3: 1080p/raw10
+ * mode = 2, start stream for sensor Mode 5: 720p/raw10
+ *
+ * Return: 0 on success, errors otherwise
+ */
+static int imx274_mode_regs(struct stimx274 *priv, int mode)
+{
+	int err = 0;
+
+	err = imx274_write_table(priv, mode_table[IMX274_MODE_START_STREAM_1]);
+	if (err)
+		return err;
+
+	err = imx274_write_table(priv, mode_table[IMX274_MODE_START_STREAM_2]);
+	if (err)
+		return err;
+
+	err = imx274_write_table(priv, mode_table[mode]);
+
+	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, mode_table[IMX274_MODE_START_STREAM_3]);
+	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, mode_table[IMX274_MODE_START_STREAM_4]);
+	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;
+}
+
+/**
+ * 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);
+	struct i2c_client *client = imx274->client;
+	int index;
+
+	dev_dbg(&client->dev,
+		"%s: width = %d height = %d code = %d mbus_code = %d\n",
+		__func__, fmt->width, fmt->height, fmt->code,
+		imx274_formats[imx274->mode_index].mbus_code);
+
+	mutex_lock(&imx274->lock);
+
+	for (index = 0; index < ARRAY_SIZE(imx274_formats); index++) {
+		if (imx274_formats[index].size.width == fmt->width &&
+		    imx274_formats[index].size.height == fmt->height)
+			break;
+	}
+
+	if (index >= ARRAY_SIZE(imx274_formats)) {
+		/* default to first format */
+		index = 0;
+	}
+
+	imx274->mode_index = index;
+
+	if (fmt->width > IMX274_MAX_WIDTH)
+		fmt->width = IMX274_MAX_WIDTH;
+	if (fmt->height > IMX274_MAX_HEIGHT)
+		fmt->height = IMX274_MAX_HEIGHT;
+	fmt->width = fmt->width & (~IMX274_MASK_LSB_2_BITS);
+	fmt->height = fmt->height & (~IMX274_MASK_LSB_2_BITS);
+	fmt->field = V4L2_FIELD_NONE;
+
+	if (format->which == V4L2_SUBDEV_FORMAT_TRY)
+		cfg->try_fmt = *fmt;
+	else
+		imx274->format = *fmt;
+
+	mutex_unlock(&imx274->lock);
+	return 0;
+}
+
+/**
+ * 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) {
+		/*
+		 * exposure time range is decided by frame interval
+		 * need to update it after frame interal 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, imx274->ctrls.exposure->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 = %d\n", __func__,
+		on ? "Stream Start" : "Stream Stop", imx274->mode_index);
+
+	mutex_lock(&imx274->lock);
+
+	if (on) {
+		/* load mode registers */
+		imx274_mode_regs(imx274, imx274->mode_index);
+		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,
+					 mode_table[IMX274_MODE_STOP_STREAM]);
+		if (ret)
+			goto fail;
+	}
+
+	mutex_unlock(&imx274->lock);
+	dev_dbg(&imx274->client->dev,
+		"%s : Done: mode = %d\n", __func__, imx274->mode_index);
+	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;
+	u16 svr;
+	u32 vmax;
+	u8 reg_val[3];
+
+	/* svr */
+	err = imx274_read_reg(priv, IMX274_SVR_REG_LSB, &reg_val[0]);
+	if (err)
+		goto fail;
+
+	err = imx274_read_reg(priv, IMX274_SVR_REG_MSB, &reg_val[1]);
+	if (err)
+		goto fail;
+
+	svr = (reg_val[1] << IMX274_SHIFT_8_BITS) + reg_val[0];
+
+	/* vmax */
+	err = imx274_read_reg(priv, IMX274_FRAME_LENGTH_ADDR_3, &reg_val[0]);
+	if (err)
+		goto fail;
+
+	err = imx274_read_reg(priv, IMX274_FRAME_LENGTH_ADDR_2, &reg_val[1]);
+	if (err)
+		goto fail;
+
+	err = imx274_read_reg(priv, IMX274_FRAME_LENGTH_ADDR_1, &reg_val[2]);
+	if (err)
+		goto fail;
+
+	vmax = ((reg_val[2] & IMX274_MASK_LSB_3_BITS) << IMX274_SHIFT_16_BITS)
+		+ (reg_val[1] << IMX274_SHIFT_8_BITS) + reg_val[0];
+
+	*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 < min_frame_len[priv->mode_index])
+		*frame_length = min_frame_len[priv->mode_index];
+
+	*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 < min_SHR[priv->mode_index])
+		*val = min_SHR[priv->mode_index];
+
+	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);
+}
+
+static inline void imx274_calculate_gain_regs(struct reg_8 regs[2], u16 gain)
+{
+	regs->addr = IMX274_ANALOG_GAIN_ADDR_MSB;
+	regs->val = (gain >> IMX274_SHIFT_8_BITS) & IMX274_MASK_LSB_3_BITS;
+
+	(regs + 1)->addr = IMX274_ANALOG_GAIN_ADDR_LSB;
+	(regs + 1)->val = (gain) & IMX274_MASK_LSB_8_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)
+{
+	struct reg_8 reg_list[2];
+	int err;
+	u32 gain, analog_gain, digital_gain, gain_reg;
+	int i;
+
+	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;
+
+	imx274_calculate_gain_regs(reg_list, (u16)gain_reg);
+
+	for (i = 0; i < ARRAY_SIZE(reg_list); i++) {
+		err = imx274_write_reg(priv, reg_list[i].addr,
+				       reg_list[i].val);
+		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;
+}
+
+static inline void imx274_calculate_coarse_time_regs(struct reg_8 regs[2],
+						     u32 coarse_time)
+{
+	regs->addr = IMX274_COARSE_TIME_ADDR_MSB;
+	regs->val = (coarse_time >> IMX274_SHIFT_8_BITS)
+			& IMX274_MASK_LSB_8_BITS;
+	(regs + 1)->addr = IMX274_COARSE_TIME_ADDR_LSB;
+	(regs + 1)->val = (coarse_time) & IMX274_MASK_LSB_8_BITS;
+}
+
+/*
+ * 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)
+{
+	struct reg_8 reg_list[2];
+	int err;
+	u32 coarse_time, frame_length;
+	int i;
+
+	coarse_time = *val;
+
+	/* convert exposure_time to appropriate SHR value */
+	err = imx274_clamp_coarse_time(priv, &coarse_time, &frame_length);
+	if (err)
+		goto fail;
+
+	/* prepare SHR registers */
+	imx274_calculate_coarse_time_regs(reg_list, coarse_time);
+
+	/* write to SHR registers */
+	for (i = 0; i < ARRAY_SIZE(reg_list); i++) {
+		err = imx274_write_reg(priv, reg_list[i].addr,
+				       reg_list[i].val);
+		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;
+	u16 hmax;
+	u8 reg_val[2];
+	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] */
+
+	/* obtain HMAX value */
+	err = imx274_read_reg(priv, IMX274_HMAX_REG_LSB, &reg_val[0]);
+	if (err)
+		goto fail;
+	err = imx274_read_reg(priv, IMX274_HMAX_REG_MSB, &reg_val[1]);
+	if (err)
+		goto fail;
+	hmax = (reg_val[1] << IMX274_SHIFT_8_BITS) + reg_val[0];
+	if (hmax == 0) {
+		err = -EINVAL;
+		goto fail;
+	}
+
+	coarse_time = (IMX274_PIXCLK_CONST1 / IMX274_PIXCLK_CONST2 * val
+			- nocpiop[priv->mode_index]) / 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 + nocpiop[priv->mode_index])
+			/ (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, "VFILP 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;
+}
+
+static inline void imx274_calculate_frame_length_regs(struct reg_8 regs[3],
+						      u32 frame_length)
+{
+	regs->addr = IMX274_FRAME_LENGTH_ADDR_1;
+	regs->val = (frame_length >> IMX274_SHIFT_16_BITS)
+			& IMX274_MASK_LSB_4_BITS;
+	(regs + 1)->addr = IMX274_FRAME_LENGTH_ADDR_2;
+	(regs + 1)->val = (frame_length >> IMX274_SHIFT_8_BITS)
+			& IMX274_MASK_LSB_8_BITS;
+	(regs + 2)->addr = IMX274_FRAME_LENGTH_ADDR_3;
+	(regs + 2)->val = (frame_length) & IMX274_MASK_LSB_8_BITS;
+}
+
+/*
+ * 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)
+{
+	struct reg_8 reg_list[3];
+	int err;
+	u32 frame_length;
+	int i;
+
+	dev_dbg(&priv->client->dev, "%s : input length = %d\n",
+		__func__, val);
+
+	frame_length = (u32)val;
+
+	imx274_calculate_frame_length_regs(reg_list, frame_length);
+	for (i = 0; i < ARRAY_SIZE(reg_list); i++) {
+		err = imx274_write_reg(priv, reg_list[i].addr,
+				       reg_list[i].val);
+		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;
+	u16 svr;
+	u16 hmax;
+	u8 reg_val[2];
+
+	dev_dbg(&priv->client->dev, "%s: input frame interval = %d / %d",
+		__func__, frame_interval.numerator,
+		frame_interval.denominator);
+
+	if (frame_interval.numerator == 0) {
+		err = -EINVAL;
+		goto fail;
+	}
+
+	req_frame_rate = (u32)(frame_interval.denominator
+				/ frame_interval.numerator);
+
+	/* boundary check */
+	if (req_frame_rate > max_frame_rate[priv->mode_index]) {
+		frame_interval.numerator = 1;
+		frame_interval.denominator =
+					max_frame_rate[priv->mode_index];
+	} 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
+	 */
+
+	/* SVR */
+	err = imx274_read_reg(priv, IMX274_SVR_REG_LSB, &reg_val[0]);
+	if (err)
+		goto fail;
+	err = imx274_read_reg(priv, IMX274_SVR_REG_MSB, &reg_val[1]);
+	if (err)
+		goto fail;
+	svr = (reg_val[1] << IMX274_SHIFT_8_BITS) + reg_val[0];
+	dev_dbg(&priv->client->dev,
+		"%s : register SVR = %d\n", __func__, svr);
+
+	/* HMAX */
+	err = imx274_read_reg(priv, IMX274_HMAX_REG_LSB, &reg_val[0]);
+	if (err)
+		goto fail;
+	err = imx274_read_reg(priv, IMX274_HMAX_REG_MSB, &reg_val[1]);
+	if (err)
+		goto fail;
+	hmax = (reg_val[1] << IMX274_SHIFT_8_BITS) + reg_val[0];
+	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,
+};
+
+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,
+			const struct i2c_device_id *id)
+{
+	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 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);
+	strlcpy(sd->name, DRIVER_NAME, sizeof(sd->name));
+	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, 2);
+	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;
+	}
+
+	/* initialize format */
+	imx274->mode_index = IMX274_MODE_3840X2160;
+	imx274->format.width = imx274_formats[0].size.width;
+	imx274->format.height = imx274_formats[0].size.height;
+	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;
+
+	/* 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_async_unregister_subdev(sd);
+	v4l2_ctrl_handler_free(sd->ctrl_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, mode_table[IMX274_MODE_STOP_STREAM]);
+
+	v4l2_async_unregister_subdev(sd);
+	v4l2_ctrl_handler_free(sd->ctrl_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		= 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");