/****************************************************************************
 *
 *  Filename: cpia2_usb.c
 *
 *  Copyright 2001, STMicrolectronics, Inc.
 *      Contact:  steve.miller@st.com
 *
 *  Description:
 *     This is a USB driver for CPia2 based video cameras.
 *     The infrastructure of this driver is based on the cpia usb driver by
 *     Jochen Scharrlach and Johannes Erdfeldt.
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that 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, write to the Free Software
 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 *  Stripped of 2.4 stuff ready for main kernel submit by
 *              Alan Cox <alan@lxorguk.ukuu.org.uk>
 ****************************************************************************/

#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/usb.h>
#include <linux/module.h>

#include "cpia2.h"

static int frame_sizes[] = {
        0,      // USBIF_CMDONLY
        0,      // USBIF_BULK
        128,    // USBIF_ISO_1
        384,    // USBIF_ISO_2
        640,    // USBIF_ISO_3
        768,    // USBIF_ISO_4
        896,    // USBIF_ISO_5
        1023,   // USBIF_ISO_6
};

#define FRAMES_PER_DESC    10
#define FRAME_SIZE_PER_DESC   frame_sizes[cam->cur_alt]

static void process_frame(struct camera_data *cam);
static void cpia2_usb_complete(struct urb *urb);
static int cpia2_usb_probe(struct usb_interface *intf,
                           const struct usb_device_id *id);
static void cpia2_usb_disconnect(struct usb_interface *intf);
static int cpia2_usb_suspend(struct usb_interface *intf, pm_message_t message);
static int cpia2_usb_resume(struct usb_interface *intf);

static void free_sbufs(struct camera_data *cam);
static void add_APPn(struct camera_data *cam);
static void add_COM(struct camera_data *cam);
static int submit_urbs(struct camera_data *cam);
static int set_alternate(struct camera_data *cam, unsigned int alt);
static int configure_transfer_mode(struct camera_data *cam, unsigned int alt);

static struct usb_device_id cpia2_id_table[] = {
        {USB_DEVICE(0x0553, 0x0100)},
        {USB_DEVICE(0x0553, 0x0140)},
        {USB_DEVICE(0x0553, 0x0151)},  /* STV0676 */
        {}                      /* Terminating entry */
};
MODULE_DEVICE_TABLE(usb, cpia2_id_table);

static struct usb_driver cpia2_driver = {
        .name           = "cpia2",
        .probe          = cpia2_usb_probe,
        .disconnect     = cpia2_usb_disconnect,
        .suspend        = cpia2_usb_suspend,
        .resume         = cpia2_usb_resume,
        .reset_resume   = cpia2_usb_resume,
        .id_table       = cpia2_id_table
};


/******************************************************************************
 *
 *  process_frame
 *
 *****************************************************************************/
static void process_frame(struct camera_data *cam)
{
        static int frame_count;

        unsigned char *inbuff = cam->workbuff->data;

        DBG("Processing frame #%d, current:%d\n",
            cam->workbuff->num, cam->curbuff->num);

        if(cam->workbuff->length > cam->workbuff->max_length)
                cam->workbuff->max_length = cam->workbuff->length;

        if ((inbuff[0] == 0xFF) && (inbuff[1] == 0xD8)) {
                frame_count++;
        } else {
                cam->workbuff->status = FRAME_ERROR;
                DBG("Start of frame not found\n");
                return;
        }

        /***
         * Now the output buffer should have a JPEG image in it.
         ***/
        if(!cam->first_image_seen) {
                /* Always skip the first image after streaming
                 * starts. It is almost certainly corrupt. */
                cam->first_image_seen = 1;
                cam->workbuff->status = FRAME_EMPTY;
                return;
        }
        if (cam->workbuff->length > 3) {
                if(cam->mmapped &&
                   cam->workbuff->length < cam->workbuff->max_length) {
                        /* No junk in the buffers */
                        memset(cam->workbuff->data+cam->workbuff->length,
                               0, cam->workbuff->max_length-
                                  cam->workbuff->length);
                }
                cam->workbuff->max_length = cam->workbuff->length;
                cam->workbuff->status = FRAME_READY;

                if(!cam->mmapped && cam->num_frames > 2) {
                        /* During normal reading, the most recent
                         * frame will be read.  If the current frame
                         * hasn't started reading yet, it will never
                         * be read, so mark it empty.  If the buffer is
                         * mmapped, or we have few buffers, we need to
                         * wait for the user to free the buffer.
                         *
                         * NOTE: This is not entirely foolproof with 3
                         * buffers, but it would take an EXTREMELY
                         * overloaded system to cause problems (possible
                         * image data corruption).  Basically, it would
                         * need to take more time to execute cpia2_read
                         * than it would for the camera to send
                         * cam->num_frames-2 frames before problems
                         * could occur.
                         */
                        cam->curbuff->status = FRAME_EMPTY;
                }
                cam->curbuff = cam->workbuff;
                cam->workbuff = cam->workbuff->next;
                DBG("Changed buffers, work:%d, current:%d\n",
                    cam->workbuff->num, cam->curbuff->num);
                return;
        } else {
                DBG("Not enough data for an image.\n");
        }

        cam->workbuff->status = FRAME_ERROR;
        return;
}

/******************************************************************************
 *
 *  add_APPn
 *
 *  Adds a user specified APPn record
 *****************************************************************************/
static void add_APPn(struct camera_data *cam)
{
        if(cam->APP_len > 0) {
                cam->workbuff->data[cam->workbuff->length++] = 0xFF;
                cam->workbuff->data[cam->workbuff->length++] = 0xE0+cam->APPn;
                cam->workbuff->data[cam->workbuff->length++] = 0;
                cam->workbuff->data[cam->workbuff->length++] = cam->APP_len+2;
                memcpy(cam->workbuff->data+cam->workbuff->length,
                       cam->APP_data, cam->APP_len);
                cam->workbuff->length += cam->APP_len;
        }
}

/******************************************************************************
 *
 *  add_COM
 *
 *  Adds a user specified COM record
 *****************************************************************************/
static void add_COM(struct camera_data *cam)
{
        if(cam->COM_len > 0) {
                cam->workbuff->data[cam->workbuff->length++] = 0xFF;
                cam->workbuff->data[cam->workbuff->length++] = 0xFE;
                cam->workbuff->data[cam->workbuff->length++] = 0;
                cam->workbuff->data[cam->workbuff->length++] = cam->COM_len+2;
                memcpy(cam->workbuff->data+cam->workbuff->length,
                       cam->COM_data, cam->COM_len);
                cam->workbuff->length += cam->COM_len;
        }
}

/******************************************************************************
 *
 *  cpia2_usb_complete
 *
 *  callback when incoming packet is received
 *****************************************************************************/
static void cpia2_usb_complete(struct urb *urb)
{
        int i;
        unsigned char *cdata;
        static bool frame_ready = false;
        struct camera_data *cam = (struct camera_data *) urb->context;

        if (urb->status!=0) {
                if (!(urb->status == -ENOENT ||
                      urb->status == -ECONNRESET ||
                      urb->status == -ESHUTDOWN))
                {
                        DBG("urb->status = %d!\n", urb->status);
                }
                DBG("Stopping streaming\n");
                return;
        }

        if (!cam->streaming || !video_is_registered(&cam->vdev)) {
                LOG("Will now stop the streaming: streaming = %d, present=%d\n",
                    cam->streaming, video_is_registered(&cam->vdev));
                return;
        }

        /***
         * Packet collater
         ***/
        //DBG("Collating %d packets\n", urb->number_of_packets);
        for (i = 0; i < urb->number_of_packets; i++) {
                u16 checksum, iso_checksum;
                int j;
                int n = urb->iso_frame_desc[i].actual_length;
                int st = urb->iso_frame_desc[i].status;

                if(cam->workbuff->status == FRAME_READY) {
                        struct framebuf *ptr;
                        /* Try to find an available buffer */
                        DBG("workbuff full, searching\n");
                        for (ptr = cam->workbuff->next;
                             ptr != cam->workbuff;
                             ptr = ptr->next)
                        {
                                if (ptr->status == FRAME_EMPTY) {
                                        ptr->status = FRAME_READING;
                                        ptr->length = 0;
                                        break;
                                }
                        }
                        if (ptr == cam->workbuff)
                                break; /* No READING or EMPTY buffers left */

                        cam->workbuff = ptr;
                }

                if (cam->workbuff->status == FRAME_EMPTY ||
                    cam->workbuff->status == FRAME_ERROR) {
                        cam->workbuff->status = FRAME_READING;
                        cam->workbuff->length = 0;
                }

                //DBG("   Packet %d length = %d, status = %d\n", i, n, st);
                cdata = urb->transfer_buffer + urb->iso_frame_desc[i].offset;

                if (st) {
                        LOG("cpia2 data error: [%d] len=%d, status = %d\n",
                            i, n, st);
                        if(!ALLOW_CORRUPT)
                                cam->workbuff->status = FRAME_ERROR;
                        continue;
                }

                if(n<=2)
                        continue;

                checksum = 0;
                for(j=0; j<n-2; ++j)
                        checksum += cdata[j];
                iso_checksum = cdata[j] + cdata[j+1]*256;
                if(checksum != iso_checksum) {
                        LOG("checksum mismatch: [%d] len=%d, calculated = %x, checksum = %x\n",
                            i, n, (int)checksum, (int)iso_checksum);
                        if(!ALLOW_CORRUPT) {
                                cam->workbuff->status = FRAME_ERROR;
                                continue;
                        }
                }
                n -= 2;

                if(cam->workbuff->status != FRAME_READING) {
                        if((0xFF == cdata[0] && 0xD8 == cdata[1]) ||
                           (0xD8 == cdata[0] && 0xFF == cdata[1] &&
                            0 != cdata[2])) {
                                /* frame is skipped, but increment total
                                 * frame count anyway */
                                cam->frame_count++;
                        }
                        DBG("workbuff not reading, status=%d\n",
                            cam->workbuff->status);
                        continue;
                }

                if (cam->frame_size < cam->workbuff->length + n) {
                        ERR("buffer overflow! length: %d, n: %d\n",
                            cam->workbuff->length, n);
                        cam->workbuff->status = FRAME_ERROR;
                        if(cam->workbuff->length > cam->workbuff->max_length)
                                cam->workbuff->max_length =
                                        cam->workbuff->length;
                        continue;
                }

                if (cam->workbuff->length == 0) {
                        int data_offset;
                        if ((0xD8 == cdata[0]) && (0xFF == cdata[1])) {
                                data_offset = 1;
                        } else if((0xFF == cdata[0]) && (0xD8 == cdata[1])
                                  && (0xFF == cdata[2])) {
                                data_offset = 2;
                        } else {
                                DBG("Ignoring packet, not beginning!\n");
                                continue;
                        }
                        DBG("Start of frame pattern found\n");
                        v4l2_get_timestamp(&cam->workbuff->timestamp);
                        cam->workbuff->seq = cam->frame_count++;
                        cam->workbuff->data[0] = 0xFF;
                        cam->workbuff->data[1] = 0xD8;
                        cam->workbuff->length = 2;
                        add_APPn(cam);
                        add_COM(cam);
                        memcpy(cam->workbuff->data+cam->workbuff->length,
                               cdata+data_offset, n-data_offset);
                        cam->workbuff->length += n-data_offset;
                } else if (cam->workbuff->length > 0) {
                        memcpy(cam->workbuff->data + cam->workbuff->length,
                               cdata, n);
                        cam->workbuff->length += n;
                }

                if ((cam->workbuff->length >= 3) &&
                    (cam->workbuff->data[cam->workbuff->length - 3] == 0xFF) &&
                    (cam->workbuff->data[cam->workbuff->length - 2] == 0xD9) &&
                    (cam->workbuff->data[cam->workbuff->length - 1] == 0xFF)) {
                        frame_ready = true;
                        cam->workbuff->data[cam->workbuff->length - 1] = 0;
                        cam->workbuff->length -= 1;
                } else if ((cam->workbuff->length >= 2) &&
                   (cam->workbuff->data[cam->workbuff->length - 2] == 0xFF) &&
                   (cam->workbuff->data[cam->workbuff->length - 1] == 0xD9)) {
                        frame_ready = true;
                }

                if (frame_ready) {
                        DBG("Workbuff image size = %d\n",cam->workbuff->length);
                        process_frame(cam);

                        frame_ready = false;

                        if (waitqueue_active(&cam->wq_stream))
                                wake_up_interruptible(&cam->wq_stream);
                }
        }

        if(cam->streaming) {
                /* resubmit */
                urb->dev = cam->dev;
                if ((i = usb_submit_urb(urb, GFP_ATOMIC)) != 0)
                        ERR("%s: usb_submit_urb ret %d!\n", __func__, i);
        }
}

/******************************************************************************
 *
 * configure_transfer_mode
 *
 *****************************************************************************/
static int configure_transfer_mode(struct camera_data *cam, unsigned int alt)
{
        static unsigned char iso_regs[8][4] = {
                {0x00, 0x00, 0x00, 0x00},
                {0x00, 0x00, 0x00, 0x00},
                {0xB9, 0x00, 0x00, 0x7E},
                {0xB9, 0x00, 0x01, 0x7E},
                {0xB9, 0x00, 0x02, 0x7E},
                {0xB9, 0x00, 0x02, 0xFE},
                {0xB9, 0x00, 0x03, 0x7E},
                {0xB9, 0x00, 0x03, 0xFD}
        };
        struct cpia2_command cmd;
        unsigned char reg;

        if (!video_is_registered(&cam->vdev))
                return -ENODEV;

        /***
         * Write the isoc registers according to the alternate selected
         ***/
        cmd.direction = TRANSFER_WRITE;
        cmd.buffer.block_data[0] = iso_regs[alt][0];
        cmd.buffer.block_data[1] = iso_regs[alt][1];
        cmd.buffer.block_data[2] = iso_regs[alt][2];
        cmd.buffer.block_data[3] = iso_regs[alt][3];
        cmd.req_mode = CAMERAACCESS_TYPE_BLOCK | CAMERAACCESS_VC;
        cmd.start = CPIA2_VC_USB_ISOLIM;
        cmd.reg_count = 4;
        cpia2_send_command(cam, &cmd);

        /***
         * Enable relevant streams before starting polling.
         * First read USB Stream Config Register.
         ***/
        cmd.direction = TRANSFER_READ;
        cmd.req_mode = CAMERAACCESS_TYPE_BLOCK | CAMERAACCESS_VC;
        cmd.start = CPIA2_VC_USB_STRM;
        cmd.reg_count = 1;
        cpia2_send_command(cam, &cmd);
        reg = cmd.buffer.block_data[0];

        /* Clear iso, bulk, and int */
        reg &= ~(CPIA2_VC_USB_STRM_BLK_ENABLE |
                 CPIA2_VC_USB_STRM_ISO_ENABLE |
                 CPIA2_VC_USB_STRM_INT_ENABLE);

        if (alt == USBIF_BULK) {
                DBG("Enabling bulk xfer\n");
                reg |= CPIA2_VC_USB_STRM_BLK_ENABLE;    /* Enable Bulk */
                cam->xfer_mode = XFER_BULK;
        } else if (alt >= USBIF_ISO_1) {
                DBG("Enabling ISOC xfer\n");
                reg |= CPIA2_VC_USB_STRM_ISO_ENABLE;
                cam->xfer_mode = XFER_ISOC;
        }

        cmd.buffer.block_data[0] = reg;
        cmd.direction = TRANSFER_WRITE;
        cmd.start = CPIA2_VC_USB_STRM;
        cmd.reg_count = 1;
        cmd.req_mode = CAMERAACCESS_TYPE_BLOCK | CAMERAACCESS_VC;
        cpia2_send_command(cam, &cmd);

        return 0;
}

/******************************************************************************
 *
 * cpia2_usb_change_streaming_alternate
 *
 *****************************************************************************/
int cpia2_usb_change_streaming_alternate(struct camera_data *cam,
                                         unsigned int alt)
{
        int ret = 0;

        if(alt < USBIF_ISO_1 || alt > USBIF_ISO_6)
                return -EINVAL;

        if(alt == cam->params.camera_state.stream_mode)
                return 0;

        cpia2_usb_stream_pause(cam);

        configure_transfer_mode(cam, alt);

        cam->params.camera_state.stream_mode = alt;

        /* Reset the camera to prevent image quality degradation */
        cpia2_reset_camera(cam);

        cpia2_usb_stream_resume(cam);

        return ret;
}

/******************************************************************************
 *
 * set_alternate
 *
 *****************************************************************************/
static int set_alternate(struct camera_data *cam, unsigned int alt)
{
        int ret = 0;

        if(alt == cam->cur_alt)
                return 0;

        if (cam->cur_alt != USBIF_CMDONLY) {
                DBG("Changing from alt %d to %d\n", cam->cur_alt, USBIF_CMDONLY);
                ret = usb_set_interface(cam->dev, cam->iface, USBIF_CMDONLY);
                if (ret != 0)
                        return ret;
        }
        if (alt != USBIF_CMDONLY) {
                DBG("Changing from alt %d to %d\n", USBIF_CMDONLY, alt);
                ret = usb_set_interface(cam->dev, cam->iface, alt);
                if (ret != 0)
                        return ret;
        }

        cam->old_alt = cam->cur_alt;
        cam->cur_alt = alt;

        return ret;
}

/******************************************************************************
 *
 * free_sbufs
 *
 * Free all cam->sbuf[]. All non-NULL .data and .urb members that are non-NULL
 * are assumed to be allocated. Non-NULL .urb members are also assumed to be
 * submitted (and must therefore be killed before they are freed).
 *****************************************************************************/
static void free_sbufs(struct camera_data *cam)
{
        int i;

        for (i = 0; i < NUM_SBUF; i++) {
                if(cam->sbuf[i].urb) {
                        usb_kill_urb(cam->sbuf[i].urb);
                        usb_free_urb(cam->sbuf[i].urb);
                        cam->sbuf[i].urb = NULL;
                }
                if(cam->sbuf[i].data) {
                        kfree(cam->sbuf[i].data);
                        cam->sbuf[i].data = NULL;
                }
        }
}

/*******
* Convenience functions
*******/
/****************************************************************************
 *
 *  write_packet
 *
 ***************************************************************************/
static int write_packet(struct usb_device *udev,
                        u8 request, u8 * registers, u16 start, size_t size)
{
        unsigned char *buf;
        int ret;

        if (!registers || size <= 0)
                return -EINVAL;

        buf = kmalloc(size, GFP_KERNEL);
        if (!buf)
                return -ENOMEM;

        memcpy(buf, registers, size);

        ret = usb_control_msg(udev,
                               usb_sndctrlpipe(udev, 0),
                               request,
                               USB_TYPE_VENDOR | USB_RECIP_DEVICE,
                               start,   /* value */
                               0,       /* index */
                               buf,     /* buffer */
                               size,
                               HZ);

        kfree(buf);
        return ret;
}

/****************************************************************************
 *
 *  read_packet
 *
 ***************************************************************************/
static int read_packet(struct usb_device *udev,
                       u8 request, u8 * registers, u16 start, size_t size)
{
        unsigned char *buf;
        int ret;

        if (!registers || size <= 0)
                return -EINVAL;

        buf = kmalloc(size, GFP_KERNEL);
        if (!buf)
                return -ENOMEM;

        ret = usb_control_msg(udev,
                               usb_rcvctrlpipe(udev, 0),
                               request,
                               USB_DIR_IN|USB_TYPE_VENDOR|USB_RECIP_DEVICE,
                               start,   /* value */
                               0,       /* index */
                               buf,     /* buffer */
                               size,
                               HZ);

        if (ret >= 0)
                memcpy(registers, buf, size);

        kfree(buf);

        return ret;
}

/******************************************************************************
 *
 *  cpia2_usb_transfer_cmd
 *
 *****************************************************************************/
int cpia2_usb_transfer_cmd(struct camera_data *cam,
                           void *registers,
                           u8 request, u8 start, u8 count, u8 direction)
{
        int err = 0;
        struct usb_device *udev = cam->dev;

        if (!udev) {
                ERR("%s: Internal driver error: udev is NULL\n", __func__);
                return -EINVAL;
        }

        if (!registers) {
                ERR("%s: Internal driver error: register array is NULL\n", __func__);
                return -EINVAL;
        }

        if (direction == TRANSFER_READ) {
                err = read_packet(udev, request, (u8 *)registers, start, count);
                if (err > 0)
                        err = 0;
        } else if (direction == TRANSFER_WRITE) {
                err =write_packet(udev, request, (u8 *)registers, start, count);
                if (err < 0) {
                        LOG("Control message failed, err val = %d\n", err);
                        LOG("Message: request = 0x%0X, start = 0x%0X\n",
                            request, start);
                        LOG("Message: count = %d, register[0] = 0x%0X\n",
                            count, ((unsigned char *) registers)[0]);
                } else
                        err=0;
        } else {
                LOG("Unexpected first byte of direction: %d\n",
                       direction);
                return -EINVAL;
        }

        if(err != 0)
                LOG("Unexpected error: %d\n", err);
        return err;
}


/******************************************************************************
 *
 *  submit_urbs
 *
 *****************************************************************************/
static int submit_urbs(struct camera_data *cam)
{
        struct urb *urb;
        int fx, err, i, j;

        for(i=0; i<NUM_SBUF; ++i) {
                if (cam->sbuf[i].data)
                        continue;
                cam->sbuf[i].data =
                    kmalloc(FRAMES_PER_DESC * FRAME_SIZE_PER_DESC, GFP_KERNEL);
                if (!cam->sbuf[i].data) {
                        while (--i >= 0) {
                                kfree(cam->sbuf[i].data);
                                cam->sbuf[i].data = NULL;
                        }
                        return -ENOMEM;
                }
        }

        /* We double buffer the Isoc lists, and also know the polling
         * interval is every frame (1 == (1 << (bInterval -1))).
         */
        for(i=0; i<NUM_SBUF; ++i) {
                if(cam->sbuf[i].urb) {
                        continue;
                }
                urb = usb_alloc_urb(FRAMES_PER_DESC, GFP_KERNEL);
                if (!urb) {
                        for (j = 0; j < i; j++)
                                usb_free_urb(cam->sbuf[j].urb);
                        return -ENOMEM;
                }

                cam->sbuf[i].urb = urb;
                urb->dev = cam->dev;
                urb->context = cam;
                urb->pipe = usb_rcvisocpipe(cam->dev, 1 /*ISOC endpoint*/);
                urb->transfer_flags = URB_ISO_ASAP;
                urb->transfer_buffer = cam->sbuf[i].data;
                urb->complete = cpia2_usb_complete;
                urb->number_of_packets = FRAMES_PER_DESC;
                urb->interval = 1;
                urb->transfer_buffer_length =
                        FRAME_SIZE_PER_DESC * FRAMES_PER_DESC;

                for (fx = 0; fx < FRAMES_PER_DESC; fx++) {
                        urb->iso_frame_desc[fx].offset =
                                FRAME_SIZE_PER_DESC * fx;
                        urb->iso_frame_desc[fx].length = FRAME_SIZE_PER_DESC;
                }
        }


        /* Queue the ISO urbs, and resubmit in the completion handler */
        for(i=0; i<NUM_SBUF; ++i) {
                err = usb_submit_urb(cam->sbuf[i].urb, GFP_KERNEL);
                if (err) {
                        ERR("usb_submit_urb[%d]() = %d\n", i, err);
                        return err;
                }
        }

        return 0;
}

/******************************************************************************
 *
 *  cpia2_usb_stream_start
 *
 *****************************************************************************/
int cpia2_usb_stream_start(struct camera_data *cam, unsigned int alternate)
{
        int ret;
        int old_alt;

        if(cam->streaming)
                return 0;

        if (cam->flush) {
                int i;
                DBG("Flushing buffers\n");
                for(i=0; i<cam->num_frames; ++i) {
                        cam->buffers[i].status = FRAME_EMPTY;
                        cam->buffers[i].length = 0;
                }
                cam->curbuff = &cam->buffers[0];
                cam->workbuff = cam->curbuff->next;
                cam->flush = false;
        }

        old_alt = cam->params.camera_state.stream_mode;
        cam->params.camera_state.stream_mode = 0;
        ret = cpia2_usb_change_streaming_alternate(cam, alternate);
        if (ret < 0) {
                int ret2;
                ERR("cpia2_usb_change_streaming_alternate() = %d!\n", ret);
                cam->params.camera_state.stream_mode = old_alt;
                ret2 = set_alternate(cam, USBIF_CMDONLY);
                if (ret2 < 0) {
                        ERR("cpia2_usb_change_streaming_alternate(%d) =%d has already "
                            "failed. Then tried to call "
                            "set_alternate(USBIF_CMDONLY) = %d.\n",
                            alternate, ret, ret2);
                }
        } else {
                cam->frame_count = 0;
                cam->streaming = 1;
                ret = cpia2_usb_stream_resume(cam);
        }
        return ret;
}

/******************************************************************************
 *
 *  cpia2_usb_stream_pause
 *
 *****************************************************************************/
int cpia2_usb_stream_pause(struct camera_data *cam)
{
        int ret = 0;
        if(cam->streaming) {
                free_sbufs(cam);
                ret = set_alternate(cam, USBIF_CMDONLY);
        }
        return ret;
}

/******************************************************************************
 *
 *  cpia2_usb_stream_resume
 *
 *****************************************************************************/
int cpia2_usb_stream_resume(struct camera_data *cam)
{
        int ret = 0;
        if(cam->streaming) {
                cam->first_image_seen = 0;
                ret = set_alternate(cam, cam->params.camera_state.stream_mode);
                if(ret == 0) {
                        /* for some reason the user effects need to be set
                           again when starting streaming. */
                        cpia2_do_command(cam, CPIA2_CMD_SET_USER_EFFECTS, TRANSFER_WRITE,
                                        cam->params.vp_params.user_effects);
                        ret = submit_urbs(cam);
                }
        }
        return ret;
}

/******************************************************************************
 *
 *  cpia2_usb_stream_stop
 *
 *****************************************************************************/
int cpia2_usb_stream_stop(struct camera_data *cam)
{
        int ret;

        ret = cpia2_usb_stream_pause(cam);
        cam->streaming = 0;
        configure_transfer_mode(cam, 0);
        return ret;
}

/******************************************************************************
 *
 *  cpia2_usb_probe
 *
 *  Probe and initialize.
 *****************************************************************************/
static int cpia2_usb_probe(struct usb_interface *intf,
                           const struct usb_device_id *id)
{
        struct usb_device *udev = interface_to_usbdev(intf);
        struct usb_interface_descriptor *interface;
        struct camera_data *cam;
        int ret;

        /* A multi-config CPiA2 camera? */
        if (udev->descriptor.bNumConfigurations != 1)
                return -ENODEV;
        interface = &intf->cur_altsetting->desc;

        /* If we get to this point, we found a CPiA2 camera */
        LOG("CPiA2 USB camera found\n");

        cam = cpia2_init_camera_struct(intf);
        if (cam == NULL)
                return -ENOMEM;

        cam->dev = udev;
        cam->iface = interface->bInterfaceNumber;

        ret = set_alternate(cam, USBIF_CMDONLY);
        if (ret < 0) {
                ERR("%s: usb_set_interface error (ret = %d)\n", __func__, ret);
                kfree(cam);
                return ret;
        }


        if((ret = cpia2_init_camera(cam)) < 0) {
                ERR("%s: failed to initialize cpia2 camera (ret = %d)\n", __func__, ret);
                kfree(cam);
                return ret;
        }
        LOG("  CPiA Version: %d.%02d (%d.%d)\n",
               cam->params.version.firmware_revision_hi,
               cam->params.version.firmware_revision_lo,
               cam->params.version.asic_id,
               cam->params.version.asic_rev);
        LOG("  CPiA PnP-ID: %04x:%04x:%04x\n",
               cam->params.pnp_id.vendor,
               cam->params.pnp_id.product,
               cam->params.pnp_id.device_revision);
        LOG("  SensorID: %d.(version %d)\n",
               cam->params.version.sensor_flags,
               cam->params.version.sensor_rev);

        usb_set_intfdata(intf, cam);

        ret = cpia2_register_camera(cam);
        if (ret < 0) {
                ERR("%s: Failed to register cpia2 camera (ret = %d)\n", __func__, ret);
                kfree(cam);
                return ret;
        }

        return 0;
}

/******************************************************************************
 *
 *  cpia2_disconnect
 *
 *****************************************************************************/
static void cpia2_usb_disconnect(struct usb_interface *intf)
{
        struct camera_data *cam = usb_get_intfdata(intf);
        usb_set_intfdata(intf, NULL);

        DBG("Stopping stream\n");
        cpia2_usb_stream_stop(cam);

        mutex_lock(&cam->v4l2_lock);
        DBG("Unregistering camera\n");
        cpia2_unregister_camera(cam);
        v4l2_device_disconnect(&cam->v4l2_dev);
        mutex_unlock(&cam->v4l2_lock);
        v4l2_device_put(&cam->v4l2_dev);

        if(cam->buffers) {
                DBG("Wakeup waiting processes\n");
                cam->curbuff->status = FRAME_READY;
                cam->curbuff->length = 0;
                wake_up_interruptible(&cam->wq_stream);
        }

        DBG("Releasing interface\n");
        usb_driver_release_interface(&cpia2_driver, intf);

        LOG("CPiA2 camera disconnected.\n");
}

static int cpia2_usb_suspend(struct usb_interface *intf, pm_message_t message)
{
        struct camera_data *cam = usb_get_intfdata(intf);

        mutex_lock(&cam->v4l2_lock);
        if (cam->streaming) {
                cpia2_usb_stream_stop(cam);
                cam->streaming = 1;
        }
        mutex_unlock(&cam->v4l2_lock);

        dev_info(&intf->dev, "going into suspend..\n");
        return 0;
}

/* Resume device - start device. */
static int cpia2_usb_resume(struct usb_interface *intf)
{
        struct camera_data *cam = usb_get_intfdata(intf);

        mutex_lock(&cam->v4l2_lock);
        v4l2_ctrl_handler_setup(&cam->hdl);
        if (cam->streaming) {
                cam->streaming = 0;
                cpia2_usb_stream_start(cam,
                                cam->params.camera_state.stream_mode);
        }
        mutex_unlock(&cam->v4l2_lock);

        dev_info(&intf->dev, "coming out of suspend..\n");
        return 0;
}

/******************************************************************************
 *
 *  usb_cpia2_init
 *
 *****************************************************************************/
int cpia2_usb_init(void)
{
        return usb_register(&cpia2_driver);
}

/******************************************************************************
 *
 *  usb_cpia_cleanup
 *
 *****************************************************************************/
void cpia2_usb_cleanup(void)
{
        schedule_timeout(2 * HZ);
        usb_deregister(&cpia2_driver);
}