/*
 * Driver for the VIA Chrome integrated camera controller.
 *
 * Copyright 2009,2010 Jonathan Corbet <corbet@lwn.net>
 * Distributable under the terms of the GNU General Public License, version 2
 *
 * This work was supported by the One Laptop Per Child project
 */
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/list.h>
#include <linux/pci.h>
#include <linux/gpio.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>
#include <linux/videodev2.h>
#include <media/v4l2-device.h>
#include <media/v4l2-ioctl.h>
#include <media/v4l2-chip-ident.h>
#include <media/videobuf-dma-sg.h>
#include <linux/delay.h>
#include <linux/dma-mapping.h>
#include <linux/pm_qos_params.h>
#include <linux/via-core.h>
#include <linux/via-gpio.h>
#include <linux/via_i2c.h>
#include <asm/olpc.h>

#include "via-camera.h"

MODULE_AUTHOR("Jonathan Corbet <corbet@lwn.net>");
MODULE_DESCRIPTION("VIA framebuffer-based camera controller driver");
MODULE_LICENSE("GPL");

static int flip_image;
module_param(flip_image, bool, 0444);
MODULE_PARM_DESC(flip_image,
                "If set, the sensor will be instructed to flip the image "
                "vertically.");

static int override_serial;
module_param(override_serial, bool, 0444);
MODULE_PARM_DESC(override_serial,
                "The camera driver will normally refuse to load if "
                "the XO 1.5 serial port is enabled.  Set this option "
                "to force-enable the camera.");

/*
 * Basic window sizes.
 */
#define VGA_WIDTH       640
#define VGA_HEIGHT      480
#define QCIF_WIDTH      176
#define QCIF_HEIGHT     144

/*
 * The structure describing our camera.
 */
enum viacam_opstate { S_IDLE = 0, S_RUNNING = 1 };

struct via_camera {
        struct v4l2_device v4l2_dev;
        struct video_device vdev;
        struct v4l2_subdev *sensor;
        struct platform_device *platdev;
        struct viafb_dev *viadev;
        struct mutex lock;
        enum viacam_opstate opstate;
        unsigned long flags;
        struct pm_qos_request_list qos_request;
        /*
         * GPIO info for power/reset management
         */
        int power_gpio;
        int reset_gpio;
        /*
         * I/O memory stuff.
         */
        void __iomem *mmio;     /* Where the registers live */
        void __iomem *fbmem;    /* Frame buffer memory */
        u32 fb_offset;          /* Reserved memory offset (FB) */
        /*
         * Capture buffers and related.  The controller supports
         * up to three, so that's what we have here.  These buffers
         * live in frame buffer memory, so we don't call them "DMA".
         */
        unsigned int cb_offsets[3];     /* offsets into fb mem */
        u8 *cb_addrs[3];                /* Kernel-space addresses */
        int n_cap_bufs;                 /* How many are we using? */
        int next_buf;
        struct videobuf_queue vb_queue;
        struct list_head buffer_queue;  /* prot. by reg_lock */
        /*
         * User tracking.
         */
        int users;
        struct file *owner;
        /*
         * Video format information.  sensor_format is kept in a form
         * that we can use to pass to the sensor.  We always run the
         * sensor in VGA resolution, though, and let the controller
         * downscale things if need be.  So we keep the "real*
         * dimensions separately.
         */
        struct v4l2_pix_format sensor_format;
        struct v4l2_pix_format user_format;
        enum v4l2_mbus_pixelcode mbus_code;
};

/*
 * Yes, this is a hack, but there's only going to be one of these
 * on any system we know of.
 */
static struct via_camera *via_cam_info;

/*
 * Flag values, manipulated with bitops
 */
#define CF_DMA_ACTIVE    0      /* A frame is incoming */
#define CF_CONFIG_NEEDED 1      /* Must configure hardware */


/*
 * Nasty ugly v4l2 boilerplate.
 */
#define sensor_call(cam, optype, func, args...) \
        v4l2_subdev_call(cam->sensor, optype, func, ##args)

/*
 * Debugging and related.
 */
#define cam_err(cam, fmt, arg...) \
        dev_err(&(cam)->platdev->dev, fmt, ##arg);
#define cam_warn(cam, fmt, arg...) \
        dev_warn(&(cam)->platdev->dev, fmt, ##arg);
#define cam_dbg(cam, fmt, arg...) \
        dev_dbg(&(cam)->platdev->dev, fmt, ##arg);

/*
 * Format handling.  This is ripped almost directly from Hans's changes
 * to cafe_ccic.c.  It's a little unfortunate; until this change, we
 * didn't need to know anything about the format except its byte depth;
 * now this information must be managed at this level too.
 */
static struct via_format {
        __u8 *desc;
        __u32 pixelformat;
        int bpp;   /* Bytes per pixel */
        enum v4l2_mbus_pixelcode mbus_code;
} via_formats[] = {
        {
                .desc           = "YUYV 4:2:2",
                .pixelformat    = V4L2_PIX_FMT_YUYV,
                .mbus_code      = V4L2_MBUS_FMT_YUYV8_2X8,
                .bpp            = 2,
        },
        {
                .desc           = "RGB 565",
                .pixelformat    = V4L2_PIX_FMT_RGB565,
                .mbus_code      = V4L2_MBUS_FMT_RGB565_2X8_LE,
                .bpp            = 2,
        },
        /* RGB444 and Bayer should be doable, but have never been
           tested with this driver. */
};
#define N_VIA_FMTS ARRAY_SIZE(via_formats)

static struct via_format *via_find_format(u32 pixelformat)
{
        unsigned i;

        for (i = 0; i < N_VIA_FMTS; i++)
                if (via_formats[i].pixelformat == pixelformat)
                        return via_formats + i;
        /* Not found? Then return the first format. */
        return via_formats;
}


/*--------------------------------------------------------------------------*/
/*
 * Sensor power/reset management.  This piece is OLPC-specific for
 * sure; other configurations will have things connected differently.
 */
static int via_sensor_power_setup(struct via_camera *cam)
{
        int ret;

        cam->power_gpio = viafb_gpio_lookup("VGPIO3");
        cam->reset_gpio = viafb_gpio_lookup("VGPIO2");
        if (cam->power_gpio < 0 || cam->reset_gpio < 0) {
                dev_err(&cam->platdev->dev, "Unable to find GPIO lines\n");
                return -EINVAL;
        }
        ret = gpio_request(cam->power_gpio, "viafb-camera");
        if (ret) {
                dev_err(&cam->platdev->dev, "Unable to request power GPIO\n");
                return ret;
        }
        ret = gpio_request(cam->reset_gpio, "viafb-camera");
        if (ret) {
                dev_err(&cam->platdev->dev, "Unable to request reset GPIO\n");
                gpio_free(cam->power_gpio);
                return ret;
        }
        gpio_direction_output(cam->power_gpio, 0);
        gpio_direction_output(cam->reset_gpio, 0);
        return 0;
}

/*
 * Power up the sensor and perform the reset dance.
 */
static void via_sensor_power_up(struct via_camera *cam)
{
        gpio_set_value(cam->power_gpio, 1);
        gpio_set_value(cam->reset_gpio, 0);
        msleep(20);  /* Probably excessive */
        gpio_set_value(cam->reset_gpio, 1);
        msleep(20);
}

static void via_sensor_power_down(struct via_camera *cam)
{
        gpio_set_value(cam->power_gpio, 0);
        gpio_set_value(cam->reset_gpio, 0);
}


static void via_sensor_power_release(struct via_camera *cam)
{
        via_sensor_power_down(cam);
        gpio_free(cam->power_gpio);
        gpio_free(cam->reset_gpio);
}

/* --------------------------------------------------------------------------*/
/* Sensor ops */

/*
 * Manage the ov7670 "flip" bit, which needs special help.
 */
static int viacam_set_flip(struct via_camera *cam)
{
        struct v4l2_control ctrl;

        memset(&ctrl, 0, sizeof(ctrl));
        ctrl.id = V4L2_CID_VFLIP;
        ctrl.value = flip_image;
        return sensor_call(cam, core, s_ctrl, &ctrl);
}

/*
 * Configure the sensor.  It's up to the caller to ensure
 * that the camera is in the correct operating state.
 */
static int viacam_configure_sensor(struct via_camera *cam)
{
        struct v4l2_mbus_framefmt mbus_fmt;
        int ret;

        v4l2_fill_mbus_format(&mbus_fmt, &cam->sensor_format, cam->mbus_code);
        ret = sensor_call(cam, core, init, 0);
        if (ret == 0)
                ret = sensor_call(cam, video, s_mbus_fmt, &mbus_fmt);
        /*
         * OV7670 does weird things if flip is set *before* format...
         */
        if (ret == 0)
                ret = viacam_set_flip(cam);
        return ret;
}



/* --------------------------------------------------------------------------*/
/*
 * Some simple register accessors; they assume that the lock is held.
 *
 * Should we want to support the second capture engine, we could
 * hide the register difference by adding 0x1000 to registers in the
 * 0x300-350 range.
 */
static inline void viacam_write_reg(struct via_camera *cam,
                int reg, int value)
{
        iowrite32(value, cam->mmio + reg);
}

static inline int viacam_read_reg(struct via_camera *cam, int reg)
{
        return ioread32(cam->mmio + reg);
}

static inline void viacam_write_reg_mask(struct via_camera *cam,
                int reg, int value, int mask)
{
        int tmp = viacam_read_reg(cam, reg);

        tmp = (tmp & ~mask) | (value & mask);
        viacam_write_reg(cam, reg, tmp);
}


/* --------------------------------------------------------------------------*/
/* Interrupt management and handling */

static irqreturn_t viacam_quick_irq(int irq, void *data)
{
        struct via_camera *cam = data;
        irqreturn_t ret = IRQ_NONE;
        int icv;

        /*
         * All we do here is to clear the interrupts and tell
         * the handler thread to wake up.
         */
        spin_lock(&cam->viadev->reg_lock);
        icv = viacam_read_reg(cam, VCR_INTCTRL);
        if (icv & VCR_IC_EAV) {
                icv |= VCR_IC_EAV|VCR_IC_EVBI|VCR_IC_FFULL;
                viacam_write_reg(cam, VCR_INTCTRL, icv);
                ret = IRQ_WAKE_THREAD;
        }
        spin_unlock(&cam->viadev->reg_lock);
        return ret;
}

/*
 * Find the next videobuf buffer which has somebody waiting on it.
 */
static struct videobuf_buffer *viacam_next_buffer(struct via_camera *cam)
{
        unsigned long flags;
        struct videobuf_buffer *buf = NULL;

        spin_lock_irqsave(&cam->viadev->reg_lock, flags);
        if (cam->opstate != S_RUNNING)
                goto out;
        if (list_empty(&cam->buffer_queue))
                goto out;
        buf = list_entry(cam->buffer_queue.next, struct videobuf_buffer, queue);
        if (!waitqueue_active(&buf->done)) {/* Nobody waiting */
                buf = NULL;
                goto out;
        }
        list_del(&buf->queue);
        buf->state = VIDEOBUF_ACTIVE;
out:
        spin_unlock_irqrestore(&cam->viadev->reg_lock, flags);
        return buf;
}

/*
 * The threaded IRQ handler.
 */
static irqreturn_t viacam_irq(int irq, void *data)
{
        int bufn;
        struct videobuf_buffer *vb;
        struct via_camera *cam = data;
        struct videobuf_dmabuf *vdma;

        /*
         * If there is no place to put the data frame, don't bother
         * with anything else.
         */
        vb = viacam_next_buffer(cam);
        if (vb == NULL)
                goto done;
        /*
         * Figure out which buffer we just completed.
         */
        bufn = (viacam_read_reg(cam, VCR_INTCTRL) & VCR_IC_ACTBUF) >> 3;
        bufn -= 1;
        if (bufn < 0)
                bufn = cam->n_cap_bufs - 1;
        /*
         * Copy over the data and let any waiters know.
         */
        vdma = videobuf_to_dma(vb);
        viafb_dma_copy_out_sg(cam->cb_offsets[bufn], vdma->sglist, vdma->sglen);
        vb->state = VIDEOBUF_DONE;
        vb->size = cam->user_format.sizeimage;
        wake_up(&vb->done);
done:
        return IRQ_HANDLED;
}


/*
 * These functions must mess around with the general interrupt
 * control register, which is relevant to much more than just the
 * camera.  Nothing else uses interrupts, though, as of this writing.
 * Should that situation change, we'll have to improve support at
 * the via-core level.
 */
static void viacam_int_enable(struct via_camera *cam)
{
        viacam_write_reg(cam, VCR_INTCTRL,
                        VCR_IC_INTEN|VCR_IC_EAV|VCR_IC_EVBI|VCR_IC_FFULL);
        viafb_irq_enable(VDE_I_C0AVEN);
}

static void viacam_int_disable(struct via_camera *cam)
{
        viafb_irq_disable(VDE_I_C0AVEN);
        viacam_write_reg(cam, VCR_INTCTRL, 0);
}



/* --------------------------------------------------------------------------*/
/* Controller operations */

/*
 * Set up our capture buffers in framebuffer memory.
 */
static int viacam_ctlr_cbufs(struct via_camera *cam)
{
        int nbuf = cam->viadev->camera_fbmem_size/cam->sensor_format.sizeimage;
        int i;
        unsigned int offset;

        /*
         * See how many buffers we can work with.
         */
        if (nbuf >= 3) {
                cam->n_cap_bufs = 3;
                viacam_write_reg_mask(cam, VCR_CAPINTC, VCR_CI_3BUFS,
                                VCR_CI_3BUFS);
        } else if (nbuf == 2) {
                cam->n_cap_bufs = 2;
                viacam_write_reg_mask(cam, VCR_CAPINTC, 0, VCR_CI_3BUFS);
        } else {
                cam_warn(cam, "Insufficient frame buffer memory\n");
                return -ENOMEM;
        }
        /*
         * Set them up.
         */
        offset = cam->fb_offset;
        for (i = 0; i < cam->n_cap_bufs; i++) {
                cam->cb_offsets[i] = offset;
                cam->cb_addrs[i] = cam->fbmem + offset;
                viacam_write_reg(cam, VCR_VBUF1 + i*4, offset & VCR_VBUF_MASK);
                offset += cam->sensor_format.sizeimage;
        }
        return 0;
}

/*
 * Set the scaling register for downscaling the image.
 *
 * This register works like this...  Vertical scaling is enabled
 * by bit 26; if that bit is set, downscaling is controlled by the
 * value in bits 16:25.  Those bits are divided by 1024 to get
 * the scaling factor; setting just bit 25 thus cuts the height
 * in half.
 *
 * Horizontal scaling works about the same, but it's enabled by
 * bit 11, with bits 0:10 giving the numerator of a fraction
 * (over 2048) for the scaling value.
 *
 * This function is naive in that, if the user departs from
 * the 3x4 VGA scaling factor, the image will distort.  We
 * could work around that if it really seemed important.
 */
static void viacam_set_scale(struct via_camera *cam)
{
        unsigned int avscale;
        int sf;

        if (cam->user_format.width == VGA_WIDTH)
                avscale = 0;
        else {
                sf = (cam->user_format.width*2048)/VGA_WIDTH;
                avscale = VCR_AVS_HEN | sf;
        }
        if (cam->user_format.height < VGA_HEIGHT) {
                sf = (1024*cam->user_format.height)/VGA_HEIGHT;
                avscale |= VCR_AVS_VEN | (sf << 16);
        }
        viacam_write_reg(cam, VCR_AVSCALE, avscale);
}


/*
 * Configure image-related information into the capture engine.
 */
static void viacam_ctlr_image(struct via_camera *cam)
{
        int cicreg;

        /*
         * Disable clock before messing with stuff - from the via
         * sample driver.
         */
        viacam_write_reg(cam, VCR_CAPINTC, ~(VCR_CI_ENABLE|VCR_CI_CLKEN));
        /*
         * Set up the controller for VGA resolution, modulo magic
         * offsets from the via sample driver.
         */
        viacam_write_reg(cam, VCR_HORRANGE, 0x06200120);
        viacam_write_reg(cam, VCR_VERTRANGE, 0x01de0000);
        viacam_set_scale(cam);
        /*
         * Image size info.
         */
        viacam_write_reg(cam, VCR_MAXDATA,
                        (cam->sensor_format.height << 16) |
                        (cam->sensor_format.bytesperline >> 3));
        viacam_write_reg(cam, VCR_MAXVBI, 0);
        viacam_write_reg(cam, VCR_VSTRIDE,
                        cam->user_format.bytesperline & VCR_VS_STRIDE);
        /*
         * Set up the capture interface control register,
         * everything but the "go" bit.
         *
         * The FIFO threshold is a bit of a magic number; 8 is what
         * VIA's sample code uses.
         */
        cicreg = VCR_CI_CLKEN |
                0x08000000 |            /* FIFO threshold */
                VCR_CI_FLDINV |         /* OLPC-specific? */
                VCR_CI_VREFINV |        /* OLPC-specific? */
                VCR_CI_DIBOTH |         /* Capture both fields */
                VCR_CI_CCIR601_8;
        if (cam->n_cap_bufs == 3)
                cicreg |= VCR_CI_3BUFS;
        /*
         * YUV formats need different byte swapping than RGB.
         */
        if (cam->user_format.pixelformat == V4L2_PIX_FMT_YUYV)
                cicreg |= VCR_CI_YUYV;
        else
                cicreg |= VCR_CI_UYVY;
        viacam_write_reg(cam, VCR_CAPINTC, cicreg);
}


static int viacam_config_controller(struct via_camera *cam)
{
        int ret;
        unsigned long flags;

        spin_lock_irqsave(&cam->viadev->reg_lock, flags);
        ret = viacam_ctlr_cbufs(cam);
        if (!ret)
                viacam_ctlr_image(cam);
        spin_unlock_irqrestore(&cam->viadev->reg_lock, flags);
        clear_bit(CF_CONFIG_NEEDED, &cam->flags);
        return ret;
}

/*
 * Make it start grabbing data.
 */
static void viacam_start_engine(struct via_camera *cam)
{
        spin_lock_irq(&cam->viadev->reg_lock);
        cam->next_buf = 0;
        viacam_write_reg_mask(cam, VCR_CAPINTC, VCR_CI_ENABLE, VCR_CI_ENABLE);
        viacam_int_enable(cam);
        (void) viacam_read_reg(cam, VCR_CAPINTC); /* Force post */
        cam->opstate = S_RUNNING;
        spin_unlock_irq(&cam->viadev->reg_lock);
}


static void viacam_stop_engine(struct via_camera *cam)
{
        spin_lock_irq(&cam->viadev->reg_lock);
        viacam_int_disable(cam);
        viacam_write_reg_mask(cam, VCR_CAPINTC, 0, VCR_CI_ENABLE);
        (void) viacam_read_reg(cam, VCR_CAPINTC); /* Force post */
        cam->opstate = S_IDLE;
        spin_unlock_irq(&cam->viadev->reg_lock);
}


/* --------------------------------------------------------------------------*/
/* Videobuf callback ops */

/*
 * buffer_setup.  The purpose of this one would appear to be to tell
 * videobuf how big a single image is.  It's also evidently up to us
 * to put some sort of limit on the maximum number of buffers allowed.
 */
static int viacam_vb_buf_setup(struct videobuf_queue *q,
                unsigned int *count, unsigned int *size)
{
        struct via_camera *cam = q->priv_data;

        *size = cam->user_format.sizeimage;
        if (*count == 0 || *count > 6)  /* Arbitrary number */
                *count = 6;
        return 0;
}

/*
 * Prepare a buffer.
 */
static int viacam_vb_buf_prepare(struct videobuf_queue *q,
                struct videobuf_buffer *vb, enum v4l2_field field)
{
        struct via_camera *cam = q->priv_data;

        vb->size = cam->user_format.sizeimage;
        vb->width = cam->user_format.width; /* bytesperline???? */
        vb->height = cam->user_format.height;
        vb->field = field;
        if (vb->state == VIDEOBUF_NEEDS_INIT) {
                int ret = videobuf_iolock(q, vb, NULL);
                if (ret)
                        return ret;
        }
        vb->state = VIDEOBUF_PREPARED;
        return 0;
}

/*
 * We've got a buffer to put data into.
 *
 * FIXME: check for a running engine and valid buffers?
 */
static void viacam_vb_buf_queue(struct videobuf_queue *q,
                struct videobuf_buffer *vb)
{
        struct via_camera *cam = q->priv_data;

        /*
         * Note that videobuf holds the lock when it calls
         * us, so we need not (indeed, cannot) take it here.
         */
        vb->state = VIDEOBUF_QUEUED;
        list_add_tail(&vb->queue, &cam->buffer_queue);
}

/*
 * Free a buffer.
 */
static void viacam_vb_buf_release(struct videobuf_queue *q,
                struct videobuf_buffer *vb)
{
        struct via_camera *cam = q->priv_data;

        videobuf_dma_unmap(&cam->platdev->dev, videobuf_to_dma(vb));
        videobuf_dma_free(videobuf_to_dma(vb));
        vb->state = VIDEOBUF_NEEDS_INIT;
}

static const struct videobuf_queue_ops viacam_vb_ops = {
        .buf_setup      = viacam_vb_buf_setup,
        .buf_prepare    = viacam_vb_buf_prepare,
        .buf_queue      = viacam_vb_buf_queue,
        .buf_release    = viacam_vb_buf_release,
};

/* --------------------------------------------------------------------------*/
/* File operations */

static int viacam_open(struct file *filp)
{
        struct via_camera *cam = video_drvdata(filp);

        filp->private_data = cam;
        /*
         * Note the new user.  If this is the first one, we'll also
         * need to power up the sensor.
         */
        mutex_lock(&cam->lock);
        if (cam->users == 0) {
                int ret = viafb_request_dma();

                if (ret) {
                        mutex_unlock(&cam->lock);
                        return ret;
                }
                via_sensor_power_up(cam);
                set_bit(CF_CONFIG_NEEDED, &cam->flags);
                /*
                 * Hook into videobuf.  Evidently this cannot fail.
                 */
                videobuf_queue_sg_init(&cam->vb_queue, &viacam_vb_ops,
                                &cam->platdev->dev, &cam->viadev->reg_lock,
                                V4L2_BUF_TYPE_VIDEO_CAPTURE, V4L2_FIELD_NONE,
                                sizeof(struct videobuf_buffer), cam, NULL);
        }
        (cam->users)++;
        mutex_unlock(&cam->lock);
        return 0;
}

static int viacam_release(struct file *filp)
{
        struct via_camera *cam = video_drvdata(filp);

        mutex_lock(&cam->lock);
        (cam->users)--;
        /*
         * If the "owner" is closing, shut down any ongoing
         * operations.
         */
        if (filp == cam->owner) {
                videobuf_stop(&cam->vb_queue);
                /*
                 * We don't hold the spinlock here, but, if release()
                 * is being called by the owner, nobody else will
                 * be changing the state.  And an extra stop would
                 * not hurt anyway.
                 */
                if (cam->opstate != S_IDLE)
                        viacam_stop_engine(cam);
                cam->owner = NULL;
        }
        /*
         * Last one out needs to turn out the lights.
         */
        if (cam->users == 0) {
                videobuf_mmap_free(&cam->vb_queue);
                via_sensor_power_down(cam);
                viafb_release_dma();
        }
        mutex_unlock(&cam->lock);
        return 0;
}

/*
 * Read a frame from the device.
 */
static ssize_t viacam_read(struct file *filp, char __user *buffer,
                size_t len, loff_t *pos)
{
        struct via_camera *cam = video_drvdata(filp);
        int ret;

        mutex_lock(&cam->lock);
        /*
         * Enforce the V4l2 "only one owner gets to read data" rule.
         */
        if (cam->owner && cam->owner != filp) {
                ret = -EBUSY;
                goto out_unlock;
        }
        cam->owner = filp;
        /*
         * Do we need to configure the hardware?
         */
        if (test_bit(CF_CONFIG_NEEDED, &cam->flags)) {
                ret = viacam_configure_sensor(cam);
                if (!ret)
                        ret = viacam_config_controller(cam);
                if (ret)
                        goto out_unlock;
        }
        /*
         * Fire up the capture engine, then have videobuf do
         * the heavy lifting.  Someday it would be good to avoid
         * stopping and restarting the engine each time.
         */
        INIT_LIST_HEAD(&cam->buffer_queue);
        viacam_start_engine(cam);
        ret = videobuf_read_stream(&cam->vb_queue, buffer, len, pos, 0,
                        filp->f_flags & O_NONBLOCK);
        viacam_stop_engine(cam);
        /* videobuf_stop() ?? */

out_unlock:
        mutex_unlock(&cam->lock);
        return ret;
}


static unsigned int viacam_poll(struct file *filp, struct poll_table_struct *pt)
{
        struct via_camera *cam = video_drvdata(filp);

        return videobuf_poll_stream(filp, &cam->vb_queue, pt);
}


static int viacam_mmap(struct file *filp, struct vm_area_struct *vma)
{
        struct via_camera *cam = video_drvdata(filp);

        return videobuf_mmap_mapper(&cam->vb_queue, vma);
}



static const struct v4l2_file_operations viacam_fops = {
        .owner          = THIS_MODULE,
        .open           = viacam_open,
        .release        = viacam_release,
        .read           = viacam_read,
        .poll           = viacam_poll,
        .mmap           = viacam_mmap,
        .unlocked_ioctl = video_ioctl2,
};

/*----------------------------------------------------------------------------*/
/*
 * The long list of v4l2 ioctl ops
 */

static int viacam_g_chip_ident(struct file *file, void *priv,
                struct v4l2_dbg_chip_ident *ident)
{
        struct via_camera *cam = priv;

        ident->ident = V4L2_IDENT_NONE;
        ident->revision = 0;
        if (v4l2_chip_match_host(&ident->match)) {
                ident->ident = V4L2_IDENT_VIA_VX855;
                return 0;
        }
        return sensor_call(cam, core, g_chip_ident, ident);
}

/*
 * Control ops are passed through to the sensor.
 */
static int viacam_queryctrl(struct file *filp, void *priv,
                struct v4l2_queryctrl *qc)
{
        struct via_camera *cam = priv;
        int ret;

        mutex_lock(&cam->lock);
        ret = sensor_call(cam, core, queryctrl, qc);
        mutex_unlock(&cam->lock);
        return ret;
}


static int viacam_g_ctrl(struct file *filp, void *priv,
                struct v4l2_control *ctrl)
{
        struct via_camera *cam = priv;
        int ret;

        mutex_lock(&cam->lock);
        ret = sensor_call(cam, core, g_ctrl, ctrl);
        mutex_unlock(&cam->lock);
        return ret;
}


static int viacam_s_ctrl(struct file *filp, void *priv,
                struct v4l2_control *ctrl)
{
        struct via_camera *cam = priv;
        int ret;

        mutex_lock(&cam->lock);
        ret = sensor_call(cam, core, s_ctrl, ctrl);
        mutex_unlock(&cam->lock);
        return ret;
}

/*
 * Only one input.
 */
static int viacam_enum_input(struct file *filp, void *priv,
                struct v4l2_input *input)
{
        if (input->index != 0)
                return -EINVAL;

        input->type = V4L2_INPUT_TYPE_CAMERA;
        input->std = V4L2_STD_ALL; /* Not sure what should go here */
        strcpy(input->name, "Camera");
        return 0;
}

static int viacam_g_input(struct file *filp, void *priv, unsigned int *i)
{
        *i = 0;
        return 0;
}

static int viacam_s_input(struct file *filp, void *priv, unsigned int i)
{
        if (i != 0)
                return -EINVAL;
        return 0;
}

static int viacam_s_std(struct file *filp, void *priv, v4l2_std_id *std)
{
        return 0;
}

/*
 * Video format stuff.  Here is our default format until
 * user space messes with things.
 */
static const struct v4l2_pix_format viacam_def_pix_format = {
        .width          = VGA_WIDTH,
        .height         = VGA_HEIGHT,
        .pixelformat    = V4L2_PIX_FMT_YUYV,
        .field          = V4L2_FIELD_NONE,
        .bytesperline   = VGA_WIDTH * 2,
        .sizeimage      = VGA_WIDTH * VGA_HEIGHT * 2,
};

static const enum v4l2_mbus_pixelcode via_def_mbus_code = V4L2_MBUS_FMT_YUYV8_2X8;

static int viacam_enum_fmt_vid_cap(struct file *filp, void *priv,
                struct v4l2_fmtdesc *fmt)
{
        if (fmt->index >= N_VIA_FMTS)
                return -EINVAL;
        strlcpy(fmt->description, via_formats[fmt->index].desc,
                        sizeof(fmt->description));
        fmt->pixelformat = via_formats[fmt->index].pixelformat;
        return 0;
}

/*
 * Figure out proper image dimensions, but always force the
 * sensor to VGA.
 */
static void viacam_fmt_pre(struct v4l2_pix_format *userfmt,
                struct v4l2_pix_format *sensorfmt)
{
        *sensorfmt = *userfmt;
        if (userfmt->width < QCIF_WIDTH || userfmt->height < QCIF_HEIGHT) {
                userfmt->width = QCIF_WIDTH;
                userfmt->height = QCIF_HEIGHT;
        }
        if (userfmt->width > VGA_WIDTH || userfmt->height > VGA_HEIGHT) {
                userfmt->width = VGA_WIDTH;
                userfmt->height = VGA_HEIGHT;
        }
        sensorfmt->width = VGA_WIDTH;
        sensorfmt->height = VGA_HEIGHT;
}

static void viacam_fmt_post(struct v4l2_pix_format *userfmt,
                struct v4l2_pix_format *sensorfmt)
{
        struct via_format *f = via_find_format(userfmt->pixelformat);

        sensorfmt->bytesperline = sensorfmt->width * f->bpp;
        sensorfmt->sizeimage = sensorfmt->height * sensorfmt->bytesperline;
        userfmt->pixelformat = sensorfmt->pixelformat;
        userfmt->field = sensorfmt->field;
        userfmt->bytesperline = 2 * userfmt->width;
        userfmt->sizeimage = userfmt->bytesperline * userfmt->height;
}


/*
 * The real work of figuring out a workable format.
 */
static int viacam_do_try_fmt(struct via_camera *cam,
                struct v4l2_pix_format *upix, struct v4l2_pix_format *spix)
{
        int ret;
        struct v4l2_mbus_framefmt mbus_fmt;
        struct via_format *f = via_find_format(upix->pixelformat);

        upix->pixelformat = f->pixelformat;
        viacam_fmt_pre(upix, spix);
        v4l2_fill_mbus_format(&mbus_fmt, upix, f->mbus_code);
        ret = sensor_call(cam, video, try_mbus_fmt, &mbus_fmt);
        v4l2_fill_pix_format(spix, &mbus_fmt);
        viacam_fmt_post(upix, spix);
        return ret;
}



static int viacam_try_fmt_vid_cap(struct file *filp, void *priv,
                struct v4l2_format *fmt)
{
        struct via_camera *cam = priv;
        struct v4l2_format sfmt;
        int ret;

        mutex_lock(&cam->lock);
        ret = viacam_do_try_fmt(cam, &fmt->fmt.pix, &sfmt.fmt.pix);
        mutex_unlock(&cam->lock);
        return ret;
}


static int viacam_g_fmt_vid_cap(struct file *filp, void *priv,
                struct v4l2_format *fmt)
{
        struct via_camera *cam = priv;

        mutex_lock(&cam->lock);
        fmt->fmt.pix = cam->user_format;
        mutex_unlock(&cam->lock);
        return 0;
}

static int viacam_s_fmt_vid_cap(struct file *filp, void *priv,
                struct v4l2_format *fmt)
{
        struct via_camera *cam = priv;
        int ret;
        struct v4l2_format sfmt;
        struct via_format *f = via_find_format(fmt->fmt.pix.pixelformat);

        /*
         * Camera must be idle or we can't mess with the
         * video setup.
         */
        mutex_lock(&cam->lock);
        if (cam->opstate != S_IDLE) {
                ret = -EBUSY;
                goto out;
        }
        /*
         * Let the sensor code look over and tweak the
         * requested formatting.
         */
        ret = viacam_do_try_fmt(cam, &fmt->fmt.pix, &sfmt.fmt.pix);
        if (ret)
                goto out;
        /*
         * OK, let's commit to the new format.
         */
        cam->user_format = fmt->fmt.pix;
        cam->sensor_format = sfmt.fmt.pix;
        cam->mbus_code = f->mbus_code;
        ret = viacam_configure_sensor(cam);
        if (!ret)
                ret = viacam_config_controller(cam);
out:
        mutex_unlock(&cam->lock);
        return ret;
}

static int viacam_querycap(struct file *filp, void *priv,
                struct v4l2_capability *cap)
{
        strcpy(cap->driver, "via-camera");
        strcpy(cap->card, "via-camera");
        cap->version = 1;
        cap->capabilities = V4L2_CAP_VIDEO_CAPTURE |
                V4L2_CAP_READWRITE | V4L2_CAP_STREAMING;
        return 0;
}

/*
 * Streaming operations - pure videobuf stuff.
 */
static int viacam_reqbufs(struct file *filp, void *priv,
                struct v4l2_requestbuffers *rb)
{
        struct via_camera *cam = priv;

        return videobuf_reqbufs(&cam->vb_queue, rb);
}

static int viacam_querybuf(struct file *filp, void *priv,
                struct v4l2_buffer *buf)
{
        struct via_camera *cam = priv;

        return videobuf_querybuf(&cam->vb_queue, buf);
}

static int viacam_qbuf(struct file *filp, void *priv, struct v4l2_buffer *buf)
{
        struct via_camera *cam = priv;

        return videobuf_qbuf(&cam->vb_queue, buf);
}

static int viacam_dqbuf(struct file *filp, void *priv, struct v4l2_buffer *buf)
{
        struct via_camera *cam = priv;

        return videobuf_dqbuf(&cam->vb_queue, buf, filp->f_flags & O_NONBLOCK);
}

static int viacam_streamon(struct file *filp, void *priv, enum v4l2_buf_type t)
{
        struct via_camera *cam = priv;
        int ret = 0;

        if (t != V4L2_BUF_TYPE_VIDEO_CAPTURE)
                return -EINVAL;

        mutex_lock(&cam->lock);
        if (cam->opstate != S_IDLE) {
                ret = -EBUSY;
                goto out;
        }
        /*
         * Enforce the V4l2 "only one owner gets to read data" rule.
         */
        if (cam->owner && cam->owner != filp) {
                ret = -EBUSY;
                goto out;
        }
        cam->owner = filp;
        /*
         * Configure things if need be.
         */
        if (test_bit(CF_CONFIG_NEEDED, &cam->flags)) {
                ret = viacam_configure_sensor(cam);
                if (ret)
                        goto out;
                ret = viacam_config_controller(cam);
                if (ret)
                        goto out;
        }
        /*
         * If the CPU goes into C3, the DMA transfer gets corrupted and
         * users start filing unsightly bug reports.  Put in a "latency"
         * requirement which will keep the CPU out of the deeper sleep
         * states.
         */
        pm_qos_add_request(&cam->qos_request, PM_QOS_CPU_DMA_LATENCY, 50);
        /*
         * Fire things up.
         */
        INIT_LIST_HEAD(&cam->buffer_queue);
        ret = videobuf_streamon(&cam->vb_queue);
        if (!ret)
                viacam_start_engine(cam);
out:
        mutex_unlock(&cam->lock);
        return ret;
}

static int viacam_streamoff(struct file *filp, void *priv, enum v4l2_buf_type t)
{
        struct via_camera *cam = priv;
        int ret;

        if (t != V4L2_BUF_TYPE_VIDEO_CAPTURE)
                return -EINVAL;
        mutex_lock(&cam->lock);
        if (cam->opstate != S_RUNNING) {
                ret = -EINVAL;
                goto out;
        }
        pm_qos_remove_request(&cam->qos_request);
        viacam_stop_engine(cam);
        /*
         * Videobuf will recycle all of the outstanding buffers, but
         * we should be sure we don't retain any references to
         * any of them.
         */
        ret = videobuf_streamoff(&cam->vb_queue);
        INIT_LIST_HEAD(&cam->buffer_queue);
out:
        mutex_unlock(&cam->lock);
        return ret;
}

/* G/S_PARM */

static int viacam_g_parm(struct file *filp, void *priv,
                struct v4l2_streamparm *parm)
{
        struct via_camera *cam = priv;
        int ret;

        mutex_lock(&cam->lock);
        ret = sensor_call(cam, video, g_parm, parm);
        mutex_unlock(&cam->lock);
        parm->parm.capture.readbuffers = cam->n_cap_bufs;
        return ret;
}

static int viacam_s_parm(struct file *filp, void *priv,
                struct v4l2_streamparm *parm)
{
        struct via_camera *cam = priv;
        int ret;

        mutex_lock(&cam->lock);
        ret = sensor_call(cam, video, s_parm, parm);
        mutex_unlock(&cam->lock);
        parm->parm.capture.readbuffers = cam->n_cap_bufs;
        return ret;
}

static int viacam_enum_framesizes(struct file *filp, void *priv,
                struct v4l2_frmsizeenum *sizes)
{
        if (sizes->index != 0)
                return -EINVAL;
        sizes->type = V4L2_FRMSIZE_TYPE_CONTINUOUS;
        sizes->stepwise.min_width = QCIF_WIDTH;
        sizes->stepwise.min_height = QCIF_HEIGHT;
        sizes->stepwise.max_width = VGA_WIDTH;
        sizes->stepwise.max_height = VGA_HEIGHT;
        sizes->stepwise.step_width = sizes->stepwise.step_height = 1;
        return 0;
}

static int viacam_enum_frameintervals(struct file *filp, void *priv,
                struct v4l2_frmivalenum *interval)
{
        struct via_camera *cam = priv;
        int ret;

        mutex_lock(&cam->lock);
        ret = sensor_call(cam, video, enum_frameintervals, interval);
        mutex_unlock(&cam->lock);
        return ret;
}



static const struct v4l2_ioctl_ops viacam_ioctl_ops = {
        .vidioc_g_chip_ident    = viacam_g_chip_ident,
        .vidioc_queryctrl       = viacam_queryctrl,
        .vidioc_g_ctrl          = viacam_g_ctrl,
        .vidioc_s_ctrl          = viacam_s_ctrl,
        .vidioc_enum_input      = viacam_enum_input,
        .vidioc_g_input         = viacam_g_input,
        .vidioc_s_input         = viacam_s_input,
        .vidioc_s_std           = viacam_s_std,
        .vidioc_enum_fmt_vid_cap = viacam_enum_fmt_vid_cap,
        .vidioc_try_fmt_vid_cap = viacam_try_fmt_vid_cap,
        .vidioc_g_fmt_vid_cap   = viacam_g_fmt_vid_cap,
        .vidioc_s_fmt_vid_cap   = viacam_s_fmt_vid_cap,
        .vidioc_querycap        = viacam_querycap,
        .vidioc_reqbufs         = viacam_reqbufs,
        .vidioc_querybuf        = viacam_querybuf,
        .vidioc_qbuf            = viacam_qbuf,
        .vidioc_dqbuf           = viacam_dqbuf,
        .vidioc_streamon        = viacam_streamon,
        .vidioc_streamoff       = viacam_streamoff,
        .vidioc_g_parm          = viacam_g_parm,
        .vidioc_s_parm          = viacam_s_parm,
        .vidioc_enum_framesizes = viacam_enum_framesizes,
        .vidioc_enum_frameintervals = viacam_enum_frameintervals,
};

/*----------------------------------------------------------------------------*/

/*
 * Power management.
 */
#ifdef CONFIG_PM

static int viacam_suspend(void *priv)
{
        struct via_camera *cam = priv;
        enum viacam_opstate state = cam->opstate;

        if (cam->opstate != S_IDLE) {
                viacam_stop_engine(cam);
                cam->opstate = state; /* So resume restarts */
        }

        return 0;
}

static int viacam_resume(void *priv)
{
        struct via_camera *cam = priv;
        int ret = 0;

        /*
         * Get back to a reasonable operating state.
         */
        via_write_reg_mask(VIASR, 0x78, 0, 0x80);
        via_write_reg_mask(VIASR, 0x1e, 0xc0, 0xc0);
        viacam_int_disable(cam);
        set_bit(CF_CONFIG_NEEDED, &cam->flags);
        /*
         * Make sure the sensor's power state is correct
         */
        if (cam->users > 0)
                via_sensor_power_up(cam);
        else
                via_sensor_power_down(cam);
        /*
         * If it was operating, try to restart it.
         */
        if (cam->opstate != S_IDLE) {
                mutex_lock(&cam->lock);
                ret = viacam_configure_sensor(cam);
                if (!ret)
                        ret = viacam_config_controller(cam);
                mutex_unlock(&cam->lock);
                if (!ret)
                        viacam_start_engine(cam);
        }

        return ret;
}

static struct viafb_pm_hooks viacam_pm_hooks = {
        .suspend = viacam_suspend,
        .resume = viacam_resume
};

#endif /* CONFIG_PM */

/*
 * Setup stuff.
 */

static struct video_device viacam_v4l_template = {
        .name           = "via-camera",
        .minor          = -1,
        .tvnorms        = V4L2_STD_NTSC_M,
        .current_norm   = V4L2_STD_NTSC_M,
        .fops           = &viacam_fops,
        .ioctl_ops      = &viacam_ioctl_ops,
        .release        = video_device_release_empty, /* Check this */
};

/*
 * The OLPC folks put the serial port on the same pin as
 * the camera.  They also get grumpy if we break the
 * serial port and keep them from using it.  So we have
 * to check the serial enable bit and not step on it.
 */
#define VIACAM_SERIAL_DEVFN 0x88
#define VIACAM_SERIAL_CREG 0x46
#define VIACAM_SERIAL_BIT 0x40

static __devinit bool viacam_serial_is_enabled(void)
{
        struct pci_bus *pbus = pci_find_bus(0, 0);
        u8 cbyte;

        pci_bus_read_config_byte(pbus, VIACAM_SERIAL_DEVFN,
                        VIACAM_SERIAL_CREG, &cbyte);
        if ((cbyte & VIACAM_SERIAL_BIT) == 0)
                return false; /* Not enabled */
        if (override_serial == 0) {
                printk(KERN_NOTICE "Via camera: serial port is enabled, " \
                                "refusing to load.\n");
                printk(KERN_NOTICE "Specify override_serial=1 to force " \
                                "module loading.\n");
                return true;
        }
        printk(KERN_NOTICE "Via camera: overriding serial port\n");
        pci_bus_write_config_byte(pbus, VIACAM_SERIAL_DEVFN,
                        VIACAM_SERIAL_CREG, cbyte & ~VIACAM_SERIAL_BIT);
        return false;
}

static __devinit int viacam_probe(struct platform_device *pdev)
{
        int ret;
        struct i2c_adapter *sensor_adapter;
        struct viafb_dev *viadev = pdev->dev.platform_data;

        /*
         * Note that there are actually two capture channels on
         * the device.  We only deal with one for now.  That
         * is encoded here; nothing else assumes it's dealing with
         * a unique capture device.
         */
        struct via_camera *cam;

        /*
         * Ensure that frame buffer memory has been set aside for
         * this purpose.  As an arbitrary limit, refuse to work
         * with less than two frames of VGA 16-bit data.
         *
         * If we ever support the second port, we'll need to set
         * aside more memory.
         */
        if (viadev->camera_fbmem_size < (VGA_HEIGHT*VGA_WIDTH*4)) {
                printk(KERN_ERR "viacam: insufficient FB memory reserved\n");
                return -ENOMEM;
        }
        if (viadev->engine_mmio == NULL) {
                printk(KERN_ERR "viacam: No I/O memory, so no pictures\n");
                return -ENOMEM;
        }

        if (machine_is_olpc() && viacam_serial_is_enabled())
                return -EBUSY;

        /*
         * Basic structure initialization.
         */
        cam = kzalloc (sizeof(struct via_camera), GFP_KERNEL);
        if (cam == NULL)
                return -ENOMEM;
        via_cam_info = cam;
        cam->platdev = pdev;
        cam->viadev = viadev;
        cam->users = 0;
        cam->owner = NULL;
        cam->opstate = S_IDLE;
        cam->user_format = cam->sensor_format = viacam_def_pix_format;
        mutex_init(&cam->lock);
        INIT_LIST_HEAD(&cam->buffer_queue);
        cam->mmio = viadev->engine_mmio;
        cam->fbmem = viadev->fbmem;
        cam->fb_offset = viadev->camera_fbmem_offset;
        cam->flags = 1 << CF_CONFIG_NEEDED;
        cam->mbus_code = via_def_mbus_code;
        /*
         * Tell V4L that we exist.
         */
        ret = v4l2_device_register(&pdev->dev, &cam->v4l2_dev);
        if (ret) {
                dev_err(&pdev->dev, "Unable to register v4l2 device\n");
                return ret;
        }
        /*
         * Convince the system that we can do DMA.
         */
        pdev->dev.dma_mask = &viadev->pdev->dma_mask;
        dma_set_mask(&pdev->dev, 0xffffffff);
        /*
         * Fire up the capture port.  The write to 0x78 looks purely
         * OLPCish; any system will need to tweak 0x1e.
         */
        via_write_reg_mask(VIASR, 0x78, 0, 0x80);
        via_write_reg_mask(VIASR, 0x1e, 0xc0, 0xc0);
        /*
         * Get the sensor powered up.
         */
        ret = via_sensor_power_setup(cam);
        if (ret)
                goto out_unregister;
        via_sensor_power_up(cam);

        /*
         * See if we can't find it on the bus.  The VIA_PORT_31 assumption
         * is OLPC-specific.  0x42 assumption is ov7670-specific.
         */
        sensor_adapter = viafb_find_i2c_adapter(VIA_PORT_31);
        cam->sensor = v4l2_i2c_new_subdev(&cam->v4l2_dev, sensor_adapter,
                        "ov7670", 0x42 >> 1, NULL);
        if (cam->sensor == NULL) {
                dev_err(&pdev->dev, "Unable to find the sensor!\n");
                ret = -ENODEV;
                goto out_power_down;
        }
        /*
         * Get the IRQ.
         */
        viacam_int_disable(cam);
        ret = request_threaded_irq(viadev->pdev->irq, viacam_quick_irq,
                        viacam_irq, IRQF_SHARED, "via-camera", cam);
        if (ret)
                goto out_power_down;
        /*
         * Tell V4l2 that we exist.
         */
        cam->vdev = viacam_v4l_template;
        cam->vdev.v4l2_dev = &cam->v4l2_dev;
        ret = video_register_device(&cam->vdev, VFL_TYPE_GRABBER, -1);
        if (ret)
                goto out_irq;
        video_set_drvdata(&cam->vdev, cam);

#ifdef CONFIG_PM
        /*
         * Hook into PM events
         */
        viacam_pm_hooks.private = cam;
        viafb_pm_register(&viacam_pm_hooks);
#endif

        /* Power the sensor down until somebody opens the device */
        via_sensor_power_down(cam);
        return 0;

out_irq:
        free_irq(viadev->pdev->irq, cam);
out_power_down:
        via_sensor_power_release(cam);
out_unregister:
        v4l2_device_unregister(&cam->v4l2_dev);
        return ret;
}

static __devexit int viacam_remove(struct platform_device *pdev)
{
        struct via_camera *cam = via_cam_info;
        struct viafb_dev *viadev = pdev->dev.platform_data;

        video_unregister_device(&cam->vdev);
        v4l2_device_unregister(&cam->v4l2_dev);
        free_irq(viadev->pdev->irq, cam);
        via_sensor_power_release(cam);
        via_cam_info = NULL;
        return 0;
}

static struct platform_driver viacam_driver = {
        .driver = {
                .name = "viafb-camera",
        },
        .probe = viacam_probe,
        .remove = viacam_remove,
};

static int viacam_init(void)
{
        return platform_driver_register(&viacam_driver);
}
module_init(viacam_init);

static void viacam_exit(void)
{
        platform_driver_unregister(&viacam_driver);
}
module_exit(viacam_exit);