// SPDX-License-Identifier: GPL-2.0
/*
 * V4L2 sensor driver for Aptina MT9V111 image sensor
 * Copyright (C) 2018 Jacopo Mondi <jacopo@jmondi.org>
 *
 * Based on mt9v032 driver
 * Copyright (C) 2010, Laurent Pinchart <laurent.pinchart@ideasonboard.com>
 * Copyright (C) 2008, Guennadi Liakhovetski <kernel@pengutronix.de>
 *
 * Based on mt9v011 driver
 * Copyright (c) 2009 Mauro Carvalho Chehab <mchehab@kernel.org>
 */

#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/gpio/consumer.h>
#include <linux/i2c.h>
#include <linux/of.h>
#include <linux/slab.h>
#include <linux/videodev2.h>
#include <linux/v4l2-mediabus.h>
#include <linux/module.h>

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

/*
 * MT9V111 is a 1/4-Inch CMOS digital image sensor with an integrated
 * Image Flow Processing (IFP) engine and a sensor core loosely based on
 * MT9V011.
 *
 * The IFP can produce several output image formats from the sensor core
 * output. This driver currently supports only YUYV format permutations.
 *
 * The driver allows manual frame rate control through set_frame_interval subdev
 * operation or V4L2_CID_V/HBLANK controls, but it is known that the
 * auto-exposure algorithm might modify the programmed frame rate. While the
 * driver initially programs the sensor with auto-exposure and
 * auto-white-balancing enabled, it is possible to disable them and more
 * precisely control the frame rate.
 *
 * While it seems possible to instruct the auto-exposure control algorithm to
 * respect a programmed frame rate when adjusting the pixel integration time,
 * registers controlling this feature are not documented in the public
 * available sensor manual used to develop this driver (09005aef80e90084,
 * MT9V111_1.fm - Rev. G 1/05 EN).
 */

#define MT9V111_CHIP_ID_HIGH                            0x82
#define MT9V111_CHIP_ID_LOW                             0x3a

#define MT9V111_R01_ADDR_SPACE                          0x01
#define MT9V111_R01_IFP                                 0x01
#define MT9V111_R01_CORE                                0x04

#define MT9V111_IFP_R06_OPMODE_CTRL                     0x06
#define         MT9V111_IFP_R06_OPMODE_CTRL_AWB_EN      BIT(1)
#define         MT9V111_IFP_R06_OPMODE_CTRL_AE_EN       BIT(14)
#define MT9V111_IFP_R07_IFP_RESET                       0x07
#define         MT9V111_IFP_R07_IFP_RESET_MASK          BIT(0)
#define MT9V111_IFP_R08_OUTFMT_CTRL                     0x08
#define         MT9V111_IFP_R08_OUTFMT_CTRL_FLICKER     BIT(11)
#define         MT9V111_IFP_R08_OUTFMT_CTRL_PCLK        BIT(5)
#define MT9V111_IFP_R3A_OUTFMT_CTRL2                    0x3a
#define         MT9V111_IFP_R3A_OUTFMT_CTRL2_SWAP_CBCR  BIT(0)
#define         MT9V111_IFP_R3A_OUTFMT_CTRL2_SWAP_YC    BIT(1)
#define         MT9V111_IFP_R3A_OUTFMT_CTRL2_SWAP_MASK  GENMASK(2, 0)
#define MT9V111_IFP_RA5_HPAN                            0xa5
#define MT9V111_IFP_RA6_HZOOM                           0xa6
#define MT9V111_IFP_RA7_HOUT                            0xa7
#define MT9V111_IFP_RA8_VPAN                            0xa8
#define MT9V111_IFP_RA9_VZOOM                           0xa9
#define MT9V111_IFP_RAA_VOUT                            0xaa
#define MT9V111_IFP_DECIMATION_MASK                     GENMASK(9, 0)
#define MT9V111_IFP_DECIMATION_FREEZE                   BIT(15)

#define MT9V111_CORE_R03_WIN_HEIGHT                     0x03
#define         MT9V111_CORE_R03_WIN_V_OFFS             2
#define MT9V111_CORE_R04_WIN_WIDTH                      0x04
#define         MT9V111_CORE_R04_WIN_H_OFFS             114
#define MT9V111_CORE_R05_HBLANK                         0x05
#define         MT9V111_CORE_R05_MIN_HBLANK             0x09
#define         MT9V111_CORE_R05_MAX_HBLANK             GENMASK(9, 0)
#define         MT9V111_CORE_R05_DEF_HBLANK             0x26
#define MT9V111_CORE_R06_VBLANK                         0x06
#define         MT9V111_CORE_R06_MIN_VBLANK             0x03
#define         MT9V111_CORE_R06_MAX_VBLANK             GENMASK(11, 0)
#define         MT9V111_CORE_R06_DEF_VBLANK             0x04
#define MT9V111_CORE_R07_OUT_CTRL                       0x07
#define         MT9V111_CORE_R07_OUT_CTRL_SAMPLE        BIT(4)
#define MT9V111_CORE_R09_PIXEL_INT                      0x09
#define         MT9V111_CORE_R09_PIXEL_INT_MASK         GENMASK(11, 0)
#define MT9V111_CORE_R0D_CORE_RESET                     0x0d
#define         MT9V111_CORE_R0D_CORE_RESET_MASK        BIT(0)
#define MT9V111_CORE_RFF_CHIP_VER                       0xff

#define MT9V111_PIXEL_ARRAY_WIDTH                       640
#define MT9V111_PIXEL_ARRAY_HEIGHT                      480

#define MT9V111_MAX_CLKIN                               27000000

/* The default sensor configuration at startup time. */
static const struct v4l2_mbus_framefmt mt9v111_def_fmt = {
        .width          = 640,
        .height         = 480,
        .code           = MEDIA_BUS_FMT_UYVY8_2X8,
        .field          = V4L2_FIELD_NONE,
        .colorspace     = V4L2_COLORSPACE_SRGB,
        .ycbcr_enc      = V4L2_YCBCR_ENC_601,
        .quantization   = V4L2_QUANTIZATION_LIM_RANGE,
        .xfer_func      = V4L2_XFER_FUNC_SRGB,
};

struct mt9v111_dev {
        struct device *dev;
        struct i2c_client *client;

        u8 addr_space;

        struct v4l2_subdev sd;
        struct media_pad pad;

        struct v4l2_ctrl *auto_awb;
        struct v4l2_ctrl *auto_exp;
        struct v4l2_ctrl *hblank;
        struct v4l2_ctrl *vblank;
        struct v4l2_ctrl_handler ctrls;

        /* Output image format and sizes. */
        struct v4l2_mbus_framefmt fmt;
        unsigned int fps;

        /* Protects power up/down sequences. */
        struct mutex pwr_mutex;
        int pwr_count;

        /* Protects stream on/off sequences. */
        struct mutex stream_mutex;
        bool streaming;

        /* Flags to mark HW settings as not yet applied. */
        bool pending;

        /* Clock provider and system clock frequency. */
        struct clk *clk;
        u32 sysclk;

        struct gpio_desc *oe;
        struct gpio_desc *standby;
        struct gpio_desc *reset;
};

#define sd_to_mt9v111(__sd) container_of((__sd), struct mt9v111_dev, sd)

/*
 * mt9v111_mbus_fmt - List all media bus formats supported by the driver.
 *
 * Only list the media bus code here. The image sizes are freely configurable
 * in the pixel array sizes range.
 *
 * The desired frame interval, in the supported frame interval range, is
 * obtained by configuring blanking as the sensor does not have a PLL but
 * only a fixed clock divider that generates the output pixel clock.
 */
static struct mt9v111_mbus_fmt {
        u32     code;
} mt9v111_formats[] = {
        {
                .code   = MEDIA_BUS_FMT_UYVY8_2X8,
        },
        {
                .code   = MEDIA_BUS_FMT_YUYV8_2X8,
        },
        {
                .code   = MEDIA_BUS_FMT_VYUY8_2X8,
        },
        {
                .code   = MEDIA_BUS_FMT_YVYU8_2X8,
        },
};

static u32 mt9v111_frame_intervals[] = {5, 10, 15, 20, 30};

/*
 * mt9v111_frame_sizes - List sensor's supported resolutions.
 *
 * Resolution generated through decimation in the IFP block from the
 * full VGA pixel array.
 */
static struct v4l2_rect mt9v111_frame_sizes[] = {
        {
                .width  = 640,
                .height = 480,
        },
        {
                .width  = 352,
                .height = 288
        },
        {
                .width  = 320,
                .height = 240,
        },
        {
                .width  = 176,
                .height = 144,
        },
        {
                .width  = 160,
                .height = 120,
        },
};

/* --- Device I/O access --- */

static int __mt9v111_read(struct i2c_client *c, u8 reg, u16 *val)
{
        struct i2c_msg msg[2];
        __be16 buf;
        int ret;

        msg[0].addr = c->addr;
        msg[0].flags = 0;
        msg[0].len = 1;
        msg[0].buf = &reg;

        msg[1].addr = c->addr;
        msg[1].flags = I2C_M_RD;
        msg[1].len = 2;
        msg[1].buf = (char *)&buf;

        ret = i2c_transfer(c->adapter, msg, 2);
        if (ret < 0) {
                dev_err(&c->dev, "i2c read transfer error: %d\n", ret);
                return ret;
        }

        *val = be16_to_cpu(buf);

        dev_dbg(&c->dev, "%s: %x=%x\n", __func__, reg, *val);

        return 0;
}

static int __mt9v111_write(struct i2c_client *c, u8 reg, u16 val)
{
        struct i2c_msg msg;
        u8 buf[3] = { 0 };
        int ret;

        buf[0] = reg;
        buf[1] = val >> 8;
        buf[2] = val & 0xff;

        msg.addr = c->addr;
        msg.flags = 0;
        msg.len = 3;
        msg.buf = (char *)buf;

        dev_dbg(&c->dev, "%s: %x = %x%x\n", __func__, reg, buf[1], buf[2]);

        ret = i2c_transfer(c->adapter, &msg, 1);
        if (ret < 0) {
                dev_err(&c->dev, "i2c write transfer error: %d\n", ret);
                return ret;
        }

        return 0;
}

static int __mt9v111_addr_space_select(struct i2c_client *c, u16 addr_space)
{
        struct v4l2_subdev *sd = i2c_get_clientdata(c);
        struct mt9v111_dev *mt9v111 = sd_to_mt9v111(sd);
        u16 val;
        int ret;

        if (mt9v111->addr_space == addr_space)
                return 0;

        ret = __mt9v111_write(c, MT9V111_R01_ADDR_SPACE, addr_space);
        if (ret)
                return ret;

        /* Verify address space has been updated */
        ret = __mt9v111_read(c, MT9V111_R01_ADDR_SPACE, &val);
        if (ret)
                return ret;

        if (val != addr_space)
                return -EINVAL;

        mt9v111->addr_space = addr_space;

        return 0;
}

static int mt9v111_read(struct i2c_client *c, u8 addr_space, u8 reg, u16 *val)
{
        int ret;

        /* Select register address space first. */
        ret = __mt9v111_addr_space_select(c, addr_space);
        if (ret)
                return ret;

        ret = __mt9v111_read(c, reg, val);
        if (ret)
                return ret;

        return 0;
}

static int mt9v111_write(struct i2c_client *c, u8 addr_space, u8 reg, u16 val)
{
        int ret;

        /* Select register address space first. */
        ret = __mt9v111_addr_space_select(c, addr_space);
        if (ret)
                return ret;

        ret = __mt9v111_write(c, reg, val);
        if (ret)
                return ret;

        return 0;
}

static int mt9v111_update(struct i2c_client *c, u8 addr_space, u8 reg,
                          u16 mask, u16 val)
{
        u16 current_val;
        int ret;

        /* Select register address space first. */
        ret = __mt9v111_addr_space_select(c, addr_space);
        if (ret)
                return ret;

        /* Read the current register value, then update it. */
        ret = __mt9v111_read(c, reg, &current_val);
        if (ret)
                return ret;

        current_val &= ~mask;
        current_val |= (val & mask);
        ret = __mt9v111_write(c, reg, current_val);
        if (ret)
                return ret;

        return 0;
}

/* --- Sensor HW operations --- */

static int __mt9v111_power_on(struct v4l2_subdev *sd)
{
        struct mt9v111_dev *mt9v111 = sd_to_mt9v111(sd);
        int ret;

        ret = clk_prepare_enable(mt9v111->clk);
        if (ret)
                return ret;

        gpiod_set_value(mt9v111->standby, 0);
        usleep_range(500, 1000);

        gpiod_set_value(mt9v111->oe, 1);
        usleep_range(500, 1000);

        return 0;
}

static int __mt9v111_power_off(struct v4l2_subdev *sd)
{
        struct mt9v111_dev *mt9v111 = sd_to_mt9v111(sd);

        gpiod_set_value(mt9v111->oe, 0);
        usleep_range(500, 1000);

        gpiod_set_value(mt9v111->standby, 1);
        usleep_range(500, 1000);

        clk_disable_unprepare(mt9v111->clk);

        return 0;
}

static int __mt9v111_hw_reset(struct mt9v111_dev *mt9v111)
{
        if (!mt9v111->reset)
                return -EINVAL;

        gpiod_set_value(mt9v111->reset, 1);
        usleep_range(500, 1000);

        gpiod_set_value(mt9v111->reset, 0);
        usleep_range(500, 1000);

        return 0;
}

static int __mt9v111_sw_reset(struct mt9v111_dev *mt9v111)
{
        struct i2c_client *c = mt9v111->client;
        int ret;

        /* Software reset core and IFP blocks. */

        ret = mt9v111_update(c, MT9V111_R01_CORE,
                             MT9V111_CORE_R0D_CORE_RESET,
                             MT9V111_CORE_R0D_CORE_RESET_MASK, 1);
        if (ret)
                return ret;
        usleep_range(500, 1000);

        ret = mt9v111_update(c, MT9V111_R01_CORE,
                             MT9V111_CORE_R0D_CORE_RESET,
                             MT9V111_CORE_R0D_CORE_RESET_MASK, 0);
        if (ret)
                return ret;
        usleep_range(500, 1000);

        ret = mt9v111_update(c, MT9V111_R01_IFP,
                             MT9V111_IFP_R07_IFP_RESET,
                             MT9V111_IFP_R07_IFP_RESET_MASK, 1);
        if (ret)
                return ret;
        usleep_range(500, 1000);

        ret = mt9v111_update(c, MT9V111_R01_IFP,
                             MT9V111_IFP_R07_IFP_RESET,
                             MT9V111_IFP_R07_IFP_RESET_MASK, 0);
        if (ret)
                return ret;
        usleep_range(500, 1000);

        return 0;
}

static int mt9v111_calc_frame_rate(struct mt9v111_dev *mt9v111,
                                   struct v4l2_fract *tpf)
{
        unsigned int fps = tpf->numerator ?
                           tpf->denominator / tpf->numerator :
                           tpf->denominator;
        unsigned int best_diff;
        unsigned int frm_cols;
        unsigned int row_pclk;
        unsigned int best_fps;
        unsigned int pclk;
        unsigned int diff;
        unsigned int idx;
        unsigned int hb;
        unsigned int vb;
        unsigned int i;
        int ret;

        /* Approximate to the closest supported frame interval. */
        best_diff = ~0L;
        for (i = 0, idx = 0; i < ARRAY_SIZE(mt9v111_frame_intervals); i++) {
                diff = abs(fps - mt9v111_frame_intervals[i]);
                if (diff < best_diff) {
                        idx = i;
                        best_diff = diff;
                }
        }
        fps = mt9v111_frame_intervals[idx];

        /*
         * The sensor does not provide a PLL circuitry and pixel clock is
         * generated dividing the master clock source by two.
         *
         * Trow = (W + Hblank + 114) * 2 * (1 / SYSCLK)
         * TFrame = Trow * (H + Vblank + 2)
         *
         * FPS = (SYSCLK / 2) / (Trow * (H + Vblank + 2))
         *
         * This boils down to tune H and V blanks to best approximate the
         * above equation.
         *
         * Test all available H/V blank values, until we reach the
         * desired frame rate.
         */
        best_fps = vb = hb = 0;
        pclk = DIV_ROUND_CLOSEST(mt9v111->sysclk, 2);
        row_pclk = MT9V111_PIXEL_ARRAY_WIDTH + 7 + MT9V111_CORE_R04_WIN_H_OFFS;
        frm_cols = MT9V111_PIXEL_ARRAY_HEIGHT + 7 + MT9V111_CORE_R03_WIN_V_OFFS;

        best_diff = ~0L;
        for (vb = MT9V111_CORE_R06_MIN_VBLANK;
             vb < MT9V111_CORE_R06_MAX_VBLANK; vb++) {
                for (hb = MT9V111_CORE_R05_MIN_HBLANK;
                     hb < MT9V111_CORE_R05_MAX_HBLANK; hb += 10) {
                        unsigned int t_frame = (row_pclk + hb) *
                                               (frm_cols + vb);
                        unsigned int t_fps = DIV_ROUND_CLOSEST(pclk, t_frame);

                        diff = abs(fps - t_fps);
                        if (diff < best_diff) {
                                best_diff = diff;
                                best_fps = t_fps;

                                if (diff == 0)
                                        break;
                        }
                }

                if (diff == 0)
                        break;
        }

        ret = v4l2_ctrl_s_ctrl_int64(mt9v111->hblank, hb);
        if (ret)
                return ret;

        ret = v4l2_ctrl_s_ctrl_int64(mt9v111->vblank, vb);
        if (ret)
                return ret;

        tpf->numerator = 1;
        tpf->denominator = best_fps;

        return 0;
}

static int mt9v111_hw_config(struct mt9v111_dev *mt9v111)
{
        struct i2c_client *c = mt9v111->client;
        u16 outfmtctrl2;
        int ret;

        /* Force device reset. */
        ret = __mt9v111_hw_reset(mt9v111);
        if (ret == -EINVAL)
                ret = __mt9v111_sw_reset(mt9v111);
        if (ret)
                return ret;

        /* Configure internal clock sample rate. */
        ret = mt9v111->sysclk < DIV_ROUND_CLOSEST(MT9V111_MAX_CLKIN, 2) ?
                                mt9v111_update(c, MT9V111_R01_CORE,
                                        MT9V111_CORE_R07_OUT_CTRL,
                                        MT9V111_CORE_R07_OUT_CTRL_SAMPLE, 1) :
                                mt9v111_update(c, MT9V111_R01_CORE,
                                        MT9V111_CORE_R07_OUT_CTRL,
                                        MT9V111_CORE_R07_OUT_CTRL_SAMPLE, 0);
        if (ret)
                return ret;

        /*
         * Configure output image format components ordering.
         *
         * TODO: IFP block can also output several RGB permutations, we only
         *       support YUYV permutations at the moment.
         */
        switch (mt9v111->fmt.code) {
        case MEDIA_BUS_FMT_YUYV8_2X8:
                        outfmtctrl2 = MT9V111_IFP_R3A_OUTFMT_CTRL2_SWAP_YC;
                        break;
        case MEDIA_BUS_FMT_VYUY8_2X8:
                        outfmtctrl2 = MT9V111_IFP_R3A_OUTFMT_CTRL2_SWAP_CBCR;
                        break;
        case MEDIA_BUS_FMT_YVYU8_2X8:
                        outfmtctrl2 = MT9V111_IFP_R3A_OUTFMT_CTRL2_SWAP_YC |
                                      MT9V111_IFP_R3A_OUTFMT_CTRL2_SWAP_CBCR;
                        break;
        case MEDIA_BUS_FMT_UYVY8_2X8:
        default:
                        outfmtctrl2 = 0;
                        break;
        }

        ret = mt9v111_update(c, MT9V111_R01_IFP, MT9V111_IFP_R3A_OUTFMT_CTRL2,
                             MT9V111_IFP_R3A_OUTFMT_CTRL2_SWAP_MASK,
                             outfmtctrl2);
        if (ret)
                return ret;

        /*
         * Do not change default sensor's core configuration:
         * output the whole 640x480 pixel array, skip 18 columns and 6 rows.
         *
         * Instead, control the output image size through IFP block.
         *
         * TODO: No zoom&pan support. Currently we control the output image
         *       size only through decimation, with no zoom support.
         */
        ret = mt9v111_write(c, MT9V111_R01_IFP, MT9V111_IFP_RA5_HPAN,
                            MT9V111_IFP_DECIMATION_FREEZE);
        if (ret)
                return ret;

        ret = mt9v111_write(c, MT9V111_R01_IFP, MT9V111_IFP_RA8_VPAN,
                            MT9V111_IFP_DECIMATION_FREEZE);
        if (ret)
                return ret;

        ret = mt9v111_write(c, MT9V111_R01_IFP, MT9V111_IFP_RA6_HZOOM,
                            MT9V111_IFP_DECIMATION_FREEZE |
                            MT9V111_PIXEL_ARRAY_WIDTH);
        if (ret)
                return ret;

        ret = mt9v111_write(c, MT9V111_R01_IFP, MT9V111_IFP_RA9_VZOOM,
                            MT9V111_IFP_DECIMATION_FREEZE |
                            MT9V111_PIXEL_ARRAY_HEIGHT);
        if (ret)
                return ret;

        ret = mt9v111_write(c, MT9V111_R01_IFP, MT9V111_IFP_RA7_HOUT,
                            MT9V111_IFP_DECIMATION_FREEZE |
                            mt9v111->fmt.width);
        if (ret)
                return ret;

        ret = mt9v111_write(c, MT9V111_R01_IFP, MT9V111_IFP_RAA_VOUT,
                            mt9v111->fmt.height);
        if (ret)
                return ret;

        /* Apply controls to set auto exp, auto awb and timings */
        ret = v4l2_ctrl_handler_setup(&mt9v111->ctrls);
        if (ret)
                return ret;

        /*
         * Set pixel integration time to the whole frame time.
         * This value controls the shutter delay when running with AE
         * disabled. If longer than frame time, it affects the output
         * frame rate.
         */
        return mt9v111_write(c, MT9V111_R01_CORE, MT9V111_CORE_R09_PIXEL_INT,
                             MT9V111_PIXEL_ARRAY_HEIGHT);
}

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

static int mt9v111_s_power(struct v4l2_subdev *sd, int on)
{
        struct mt9v111_dev *mt9v111 = sd_to_mt9v111(sd);
        int pwr_count;
        int ret = 0;

        mutex_lock(&mt9v111->pwr_mutex);

        /*
         * Make sure we're transitioning from 0 to 1, or viceversa,
         * before actually changing the power state.
         */
        pwr_count = mt9v111->pwr_count;
        pwr_count += on ? 1 : -1;
        if (pwr_count == !!on) {
                ret = on ? __mt9v111_power_on(sd) :
                           __mt9v111_power_off(sd);
                if (!ret)
                        /* All went well, updated power counter. */
                        mt9v111->pwr_count = pwr_count;

                mutex_unlock(&mt9v111->pwr_mutex);

                return ret;
        }

        /*
         * Update power counter to keep track of how many nested calls we
         * received.
         */
        WARN_ON(pwr_count < 0 || pwr_count > 1);
        mt9v111->pwr_count = pwr_count;

        mutex_unlock(&mt9v111->pwr_mutex);

        return ret;
}

static int mt9v111_s_stream(struct v4l2_subdev *subdev, int enable)
{
        struct mt9v111_dev *mt9v111 = sd_to_mt9v111(subdev);
        int ret;

        mutex_lock(&mt9v111->stream_mutex);

        if (mt9v111->streaming == enable) {
                mutex_unlock(&mt9v111->stream_mutex);
                return 0;
        }

        ret = mt9v111_s_power(subdev, enable);
        if (ret)
                goto error_unlock;

        if (enable && mt9v111->pending) {
                ret = mt9v111_hw_config(mt9v111);
                if (ret)
                        goto error_unlock;

                /*
                 * No need to update control here as far as only H/VBLANK are
                 * supported and immediately programmed to registers in .s_ctrl
                 */

                mt9v111->pending = false;
        }

        mt9v111->streaming = enable ? true : false;
        mutex_unlock(&mt9v111->stream_mutex);

        return 0;

error_unlock:
        mutex_unlock(&mt9v111->stream_mutex);

        return ret;
}

static int mt9v111_set_frame_interval(struct v4l2_subdev *sd,
                                      struct v4l2_subdev_state *sd_state,
                                      struct v4l2_subdev_frame_interval *ival)
{
        struct mt9v111_dev *mt9v111 = sd_to_mt9v111(sd);
        struct v4l2_fract *tpf = &ival->interval;
        unsigned int fps = tpf->numerator ?
                           tpf->denominator / tpf->numerator :
                           tpf->denominator;
        unsigned int max_fps;

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

        if (!tpf->numerator)
                tpf->numerator = 1;

        mutex_lock(&mt9v111->stream_mutex);

        if (mt9v111->streaming) {
                mutex_unlock(&mt9v111->stream_mutex);
                return -EBUSY;
        }

        if (mt9v111->fps == fps) {
                mutex_unlock(&mt9v111->stream_mutex);
                return 0;
        }

        /* Make sure frame rate/image sizes constraints are respected. */
        if (mt9v111->fmt.width < QVGA_WIDTH &&
            mt9v111->fmt.height < QVGA_HEIGHT)
                max_fps = 90;
        else if (mt9v111->fmt.width < CIF_WIDTH &&
                 mt9v111->fmt.height < CIF_HEIGHT)
                max_fps = 60;
        else
                max_fps = mt9v111->sysclk <
                                DIV_ROUND_CLOSEST(MT9V111_MAX_CLKIN, 2) ? 15 :
                                                                          30;

        if (fps > max_fps) {
                mutex_unlock(&mt9v111->stream_mutex);
                return -EINVAL;
        }

        mt9v111_calc_frame_rate(mt9v111, tpf);

        mt9v111->fps = fps;
        mt9v111->pending = true;

        mutex_unlock(&mt9v111->stream_mutex);

        return 0;
}

static int mt9v111_get_frame_interval(struct v4l2_subdev *sd,
                                      struct v4l2_subdev_state *sd_state,
                                      struct v4l2_subdev_frame_interval *ival)
{
        struct mt9v111_dev *mt9v111 = sd_to_mt9v111(sd);
        struct v4l2_fract *tpf = &ival->interval;

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

        mutex_lock(&mt9v111->stream_mutex);

        tpf->numerator = 1;
        tpf->denominator = mt9v111->fps;

        mutex_unlock(&mt9v111->stream_mutex);

        return 0;
}

static struct v4l2_mbus_framefmt *__mt9v111_get_pad_format(
                                        struct mt9v111_dev *mt9v111,
                                        struct v4l2_subdev_state *sd_state,
                                        unsigned int pad,
                                        enum v4l2_subdev_format_whence which)
{
        switch (which) {
        case V4L2_SUBDEV_FORMAT_TRY:
                return v4l2_subdev_state_get_format(sd_state, pad);
        case V4L2_SUBDEV_FORMAT_ACTIVE:
                return &mt9v111->fmt;
        default:
                return NULL;
        }
}

static int mt9v111_enum_mbus_code(struct v4l2_subdev *subdev,
                                  struct v4l2_subdev_state *sd_state,
                                  struct v4l2_subdev_mbus_code_enum *code)
{
        if (code->pad || code->index > ARRAY_SIZE(mt9v111_formats) - 1)
                return -EINVAL;

        code->code = mt9v111_formats[code->index].code;

        return 0;
}

static int mt9v111_enum_frame_interval(struct v4l2_subdev *sd,
                                struct v4l2_subdev_state *sd_state,
                                struct v4l2_subdev_frame_interval_enum *fie)
{
        unsigned int i;

        if (fie->pad || fie->index >= ARRAY_SIZE(mt9v111_frame_intervals))
                return -EINVAL;

        for (i = 0; i < ARRAY_SIZE(mt9v111_frame_sizes); i++)
                if (fie->width == mt9v111_frame_sizes[i].width &&
                    fie->height == mt9v111_frame_sizes[i].height)
                        break;

        if (i == ARRAY_SIZE(mt9v111_frame_sizes))
                return -EINVAL;

        fie->interval.numerator = 1;
        fie->interval.denominator = mt9v111_frame_intervals[fie->index];

        return 0;
}

static int mt9v111_enum_frame_size(struct v4l2_subdev *subdev,
                                   struct v4l2_subdev_state *sd_state,
                                   struct v4l2_subdev_frame_size_enum *fse)
{
        if (fse->pad || fse->index >= ARRAY_SIZE(mt9v111_frame_sizes))
                return -EINVAL;

        fse->min_width = mt9v111_frame_sizes[fse->index].width;
        fse->max_width = mt9v111_frame_sizes[fse->index].width;
        fse->min_height = mt9v111_frame_sizes[fse->index].height;
        fse->max_height = mt9v111_frame_sizes[fse->index].height;

        return 0;
}

static int mt9v111_get_format(struct v4l2_subdev *subdev,
                              struct v4l2_subdev_state *sd_state,
                              struct v4l2_subdev_format *format)
{
        struct mt9v111_dev *mt9v111 = sd_to_mt9v111(subdev);

        if (format->pad)
                return -EINVAL;

        mutex_lock(&mt9v111->stream_mutex);
        format->format = *__mt9v111_get_pad_format(mt9v111, sd_state,
                                                   format->pad,
                                                   format->which);
        mutex_unlock(&mt9v111->stream_mutex);

        return 0;
}

static int mt9v111_set_format(struct v4l2_subdev *subdev,
                              struct v4l2_subdev_state *sd_state,
                              struct v4l2_subdev_format *format)
{
        struct mt9v111_dev *mt9v111 = sd_to_mt9v111(subdev);
        struct v4l2_mbus_framefmt new_fmt;
        struct v4l2_mbus_framefmt *__fmt;
        unsigned int best_fit = ~0L;
        unsigned int idx = 0;
        unsigned int i;

        mutex_lock(&mt9v111->stream_mutex);
        if (mt9v111->streaming) {
                mutex_unlock(&mt9v111->stream_mutex);
                return -EBUSY;
        }

        if (format->pad) {
                mutex_unlock(&mt9v111->stream_mutex);
                return -EINVAL;
        }

        /* Update mbus format code and sizes. */
        for (i = 0; i < ARRAY_SIZE(mt9v111_formats); i++) {
                if (format->format.code == mt9v111_formats[i].code) {
                        new_fmt.code = mt9v111_formats[i].code;
                        break;
                }
        }
        if (i == ARRAY_SIZE(mt9v111_formats))
                new_fmt.code = mt9v111_formats[0].code;

        for (i = 0; i < ARRAY_SIZE(mt9v111_frame_sizes); i++) {
                unsigned int fit = abs(mt9v111_frame_sizes[i].width -
                                       format->format.width) +
                                   abs(mt9v111_frame_sizes[i].height -
                                       format->format.height);
                if (fit < best_fit) {
                        best_fit = fit;
                        idx = i;

                        if (fit == 0)
                                break;
                }
        }
        new_fmt.width = mt9v111_frame_sizes[idx].width;
        new_fmt.height = mt9v111_frame_sizes[idx].height;

        /* Update the device (or pad) format if it has changed. */
        __fmt = __mt9v111_get_pad_format(mt9v111, sd_state, format->pad,
                                         format->which);

        /* Format hasn't changed, stop here. */
        if (__fmt->code == new_fmt.code &&
            __fmt->width == new_fmt.width &&
            __fmt->height == new_fmt.height)
                goto done;

        /* Update the format and sizes, then  mark changes as pending. */
        __fmt->code = new_fmt.code;
        __fmt->width = new_fmt.width;
        __fmt->height = new_fmt.height;

        if (format->which == V4L2_SUBDEV_FORMAT_ACTIVE)
                mt9v111->pending = true;

        dev_dbg(mt9v111->dev, "%s: mbus_code: %x - (%ux%u)\n",
                __func__, __fmt->code, __fmt->width, __fmt->height);

done:
        format->format = *__fmt;

        mutex_unlock(&mt9v111->stream_mutex);

        return 0;
}

static int mt9v111_init_state(struct v4l2_subdev *subdev,
                              struct v4l2_subdev_state *sd_state)
{
        *v4l2_subdev_state_get_format(sd_state, 0) = mt9v111_def_fmt;

        return 0;
}

static const struct v4l2_subdev_core_ops mt9v111_core_ops = {
        .s_power                = mt9v111_s_power,
};

static const struct v4l2_subdev_video_ops mt9v111_video_ops = {
        .s_stream               = mt9v111_s_stream,
};

static const struct v4l2_subdev_pad_ops mt9v111_pad_ops = {
        .enum_mbus_code         = mt9v111_enum_mbus_code,
        .enum_frame_size        = mt9v111_enum_frame_size,
        .enum_frame_interval    = mt9v111_enum_frame_interval,
        .get_fmt                = mt9v111_get_format,
        .set_fmt                = mt9v111_set_format,
        .get_frame_interval     = mt9v111_get_frame_interval,
        .set_frame_interval     = mt9v111_set_frame_interval,
};

static const struct v4l2_subdev_ops mt9v111_ops = {
        .core   = &mt9v111_core_ops,
        .video  = &mt9v111_video_ops,
        .pad    = &mt9v111_pad_ops,
};

static const struct v4l2_subdev_internal_ops mt9v111_internal_ops = {
        .init_state             = mt9v111_init_state,
};

static const struct media_entity_operations mt9v111_subdev_entity_ops = {
        .link_validate = v4l2_subdev_link_validate,
};

/* --- V4L2 ctrl --- */
static int mt9v111_s_ctrl(struct v4l2_ctrl *ctrl)
{
        struct mt9v111_dev *mt9v111 = container_of(ctrl->handler,
                                                   struct mt9v111_dev,
                                                   ctrls);
        int ret;

        mutex_lock(&mt9v111->pwr_mutex);
        /*
         * If sensor is powered down, just cache new control values,
         * no actual register access.
         */
        if (!mt9v111->pwr_count) {
                mt9v111->pending = true;
                mutex_unlock(&mt9v111->pwr_mutex);
                return 0;
        }
        mutex_unlock(&mt9v111->pwr_mutex);

        /*
         * Flickering control gets disabled if both auto exp and auto awb
         * are disabled too. If any of the two is enabled, enable it.
         *
         * Disabling flickering when ae and awb are off allows a more precise
         * control of the programmed frame rate.
         */
        if (mt9v111->auto_exp->is_new || mt9v111->auto_awb->is_new) {
                if (mt9v111->auto_exp->val == V4L2_EXPOSURE_MANUAL &&
                    mt9v111->auto_awb->val == V4L2_WHITE_BALANCE_MANUAL)
                        ret = mt9v111_update(mt9v111->client, MT9V111_R01_IFP,
                                             MT9V111_IFP_R08_OUTFMT_CTRL,
                                             MT9V111_IFP_R08_OUTFMT_CTRL_FLICKER,
                                             0);
                else
                        ret = mt9v111_update(mt9v111->client, MT9V111_R01_IFP,
                                             MT9V111_IFP_R08_OUTFMT_CTRL,
                                             MT9V111_IFP_R08_OUTFMT_CTRL_FLICKER,
                                             1);
                if (ret)
                        return ret;
        }

        ret = -EINVAL;
        switch (ctrl->id) {
        case V4L2_CID_AUTO_WHITE_BALANCE:
                ret = mt9v111_update(mt9v111->client, MT9V111_R01_IFP,
                                     MT9V111_IFP_R06_OPMODE_CTRL,
                                     MT9V111_IFP_R06_OPMODE_CTRL_AWB_EN,
                                     ctrl->val == V4L2_WHITE_BALANCE_AUTO ?
                                     MT9V111_IFP_R06_OPMODE_CTRL_AWB_EN : 0);
                break;
        case V4L2_CID_EXPOSURE_AUTO:
                ret = mt9v111_update(mt9v111->client, MT9V111_R01_IFP,
                                     MT9V111_IFP_R06_OPMODE_CTRL,
                                     MT9V111_IFP_R06_OPMODE_CTRL_AE_EN,
                                     ctrl->val == V4L2_EXPOSURE_AUTO ?
                                     MT9V111_IFP_R06_OPMODE_CTRL_AE_EN : 0);
                break;
        case V4L2_CID_HBLANK:
                ret = mt9v111_update(mt9v111->client, MT9V111_R01_CORE,
                                     MT9V111_CORE_R05_HBLANK,
                                     MT9V111_CORE_R05_MAX_HBLANK,
                                     mt9v111->hblank->val);
                break;
        case V4L2_CID_VBLANK:
                ret = mt9v111_update(mt9v111->client, MT9V111_R01_CORE,
                                     MT9V111_CORE_R06_VBLANK,
                                     MT9V111_CORE_R06_MAX_VBLANK,
                                     mt9v111->vblank->val);
                break;
        }

        return ret;
}

static const struct v4l2_ctrl_ops mt9v111_ctrl_ops = {
        .s_ctrl = mt9v111_s_ctrl,
};

static int mt9v111_chip_probe(struct mt9v111_dev *mt9v111)
{
        int ret;
        u16 val;

        ret = __mt9v111_power_on(&mt9v111->sd);
        if (ret)
                return ret;

        ret = mt9v111_read(mt9v111->client, MT9V111_R01_CORE,
                           MT9V111_CORE_RFF_CHIP_VER, &val);
        if (ret)
                goto power_off;

        if ((val >> 8) != MT9V111_CHIP_ID_HIGH &&
            (val & 0xff) != MT9V111_CHIP_ID_LOW) {
                dev_err(mt9v111->dev,
                        "Unable to identify MT9V111 chip: 0x%2x%2x\n",
                        val >> 8, val & 0xff);
                ret = -EIO;
                goto power_off;
        }

        dev_dbg(mt9v111->dev, "Chip identified: 0x%2x%2x\n",
                val >> 8, val & 0xff);

power_off:
        __mt9v111_power_off(&mt9v111->sd);

        return ret;
}

static int mt9v111_probe(struct i2c_client *client)
{
        struct mt9v111_dev *mt9v111;
        struct v4l2_fract tpf;
        int ret;

        mt9v111 = devm_kzalloc(&client->dev, sizeof(*mt9v111), GFP_KERNEL);
        if (!mt9v111)
                return -ENOMEM;

        mt9v111->dev = &client->dev;
        mt9v111->client = client;

        mt9v111->clk = devm_v4l2_sensor_clk_get(&client->dev, NULL);
        if (IS_ERR(mt9v111->clk))
                return dev_err_probe(&client->dev, PTR_ERR(mt9v111->clk),
                                     "failed to get the clock\n");

        mt9v111->sysclk = clk_get_rate(mt9v111->clk);
        if (mt9v111->sysclk > MT9V111_MAX_CLKIN)
                return -EINVAL;

        mt9v111->oe = devm_gpiod_get_optional(&client->dev, "enable",
                                              GPIOD_OUT_LOW);
        if (IS_ERR(mt9v111->oe)) {
                dev_err(&client->dev, "Unable to get GPIO \"enable\": %pe\n",
                        mt9v111->oe);
                return PTR_ERR(mt9v111->oe);
        }

        mt9v111->standby = devm_gpiod_get_optional(&client->dev, "standby",
                                                   GPIOD_OUT_HIGH);
        if (IS_ERR(mt9v111->standby)) {
                dev_err(&client->dev, "Unable to get GPIO \"standby\": %pe\n",
                        mt9v111->standby);
                return PTR_ERR(mt9v111->standby);
        }

        mt9v111->reset = devm_gpiod_get_optional(&client->dev, "reset",
                                                 GPIOD_OUT_LOW);
        if (IS_ERR(mt9v111->reset)) {
                dev_err(&client->dev, "Unable to get GPIO \"reset\": %pe\n",
                        mt9v111->reset);
                return PTR_ERR(mt9v111->reset);
        }

        mutex_init(&mt9v111->pwr_mutex);
        mutex_init(&mt9v111->stream_mutex);

        v4l2_ctrl_handler_init(&mt9v111->ctrls, 5);

        mt9v111->auto_awb = v4l2_ctrl_new_std(&mt9v111->ctrls,
                                              &mt9v111_ctrl_ops,
                                              V4L2_CID_AUTO_WHITE_BALANCE,
                                              0, 1, 1,
                                              V4L2_WHITE_BALANCE_AUTO);
        mt9v111->auto_exp = v4l2_ctrl_new_std_menu(&mt9v111->ctrls,
                                                   &mt9v111_ctrl_ops,
                                                   V4L2_CID_EXPOSURE_AUTO,
                                                   V4L2_EXPOSURE_MANUAL,
                                                   0, V4L2_EXPOSURE_AUTO);
        mt9v111->hblank = v4l2_ctrl_new_std(&mt9v111->ctrls, &mt9v111_ctrl_ops,
                                            V4L2_CID_HBLANK,
                                            MT9V111_CORE_R05_MIN_HBLANK,
                                            MT9V111_CORE_R05_MAX_HBLANK, 1,
                                            MT9V111_CORE_R05_DEF_HBLANK);
        mt9v111->vblank = v4l2_ctrl_new_std(&mt9v111->ctrls, &mt9v111_ctrl_ops,
                                            V4L2_CID_VBLANK,
                                            MT9V111_CORE_R06_MIN_VBLANK,
                                            MT9V111_CORE_R06_MAX_VBLANK, 1,
                                            MT9V111_CORE_R06_DEF_VBLANK);

        /* PIXEL_RATE is fixed: just expose it to user space. */
        v4l2_ctrl_new_std(&mt9v111->ctrls, &mt9v111_ctrl_ops,
                          V4L2_CID_PIXEL_RATE, 0,
                          DIV_ROUND_CLOSEST(mt9v111->sysclk, 2), 1,
                          DIV_ROUND_CLOSEST(mt9v111->sysclk, 2));

        if (mt9v111->ctrls.error) {
                ret = mt9v111->ctrls.error;
                goto error_free_ctrls;
        }
        mt9v111->sd.ctrl_handler = &mt9v111->ctrls;

        /* Start with default configuration: 640x480 UYVY. */
        mt9v111->fmt    = mt9v111_def_fmt;

        /* Re-calculate blankings for 640x480@15fps. */
        mt9v111->fps            = 15;
        tpf.numerator           = 1;
        tpf.denominator         = mt9v111->fps;
        mt9v111_calc_frame_rate(mt9v111, &tpf);

        mt9v111->pwr_count      = 0;
        mt9v111->addr_space     = MT9V111_R01_IFP;
        mt9v111->pending        = true;

        v4l2_i2c_subdev_init(&mt9v111->sd, client, &mt9v111_ops);
        mt9v111->sd.internal_ops = &mt9v111_internal_ops;

        mt9v111->sd.flags       |= V4L2_SUBDEV_FL_HAS_DEVNODE;
        mt9v111->sd.entity.ops  = &mt9v111_subdev_entity_ops;
        mt9v111->sd.entity.function = MEDIA_ENT_F_CAM_SENSOR;

        mt9v111->pad.flags      = MEDIA_PAD_FL_SOURCE;
        ret = media_entity_pads_init(&mt9v111->sd.entity, 1, &mt9v111->pad);
        if (ret)
                goto error_free_entity;

        ret = mt9v111_chip_probe(mt9v111);
        if (ret)
                goto error_free_entity;

        ret = v4l2_async_register_subdev(&mt9v111->sd);
        if (ret)
                goto error_free_entity;

        return 0;

error_free_entity:
        media_entity_cleanup(&mt9v111->sd.entity);

error_free_ctrls:
        v4l2_ctrl_handler_free(&mt9v111->ctrls);

        mutex_destroy(&mt9v111->pwr_mutex);
        mutex_destroy(&mt9v111->stream_mutex);

        return ret;
}

static void mt9v111_remove(struct i2c_client *client)
{
        struct v4l2_subdev *sd = i2c_get_clientdata(client);
        struct mt9v111_dev *mt9v111 = sd_to_mt9v111(sd);

        v4l2_async_unregister_subdev(sd);

        media_entity_cleanup(&sd->entity);

        v4l2_ctrl_handler_free(&mt9v111->ctrls);

        mutex_destroy(&mt9v111->pwr_mutex);
        mutex_destroy(&mt9v111->stream_mutex);
}

static const struct of_device_id mt9v111_of_match[] = {
        { .compatible = "aptina,mt9v111", },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, mt9v111_of_match);

static struct i2c_driver mt9v111_driver = {
        .driver = {
                .name = "mt9v111",
                .of_match_table = mt9v111_of_match,
        },
        .probe          = mt9v111_probe,
        .remove         = mt9v111_remove,
};

module_i2c_driver(mt9v111_driver);

MODULE_DESCRIPTION("V4L2 sensor driver for Aptina MT9V111");
MODULE_AUTHOR("Jacopo Mondi <jacopo@jmondi.org>");
MODULE_LICENSE("GPL v2");