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dvb_ca_en50221.c

/*
 * dvb_ca.c: generic DVB functions for EN50221 CAM interfaces
 *
 * Copyright (C) 2004 Andrew de Quincey
 *
 * Parts of this file were based on sources as follows:
 *
 * Copyright (C) 2003 Ralph Metzler <rjkm@metzlerbros.de>
 *
 * based on code:
 *
 * Copyright (C) 1999-2002 Ralph  Metzler
 *                       & Marcus Metzler for convergence integrated media GmbH
 *
 * 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 * Or, point your browser to http://www.gnu.org/copyleft/gpl.html
 */

#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/vmalloc.h>
#include <linux/delay.h>
#include <linux/spinlock.h>
#include <linux/sched.h>
#include <linux/kthread.h>

#include "dvb_ca_en50221.h"
#include "dvb_ringbuffer.h"

static int dvb_ca_en50221_debug;

module_param_named(cam_debug, dvb_ca_en50221_debug, int, 0644);
MODULE_PARM_DESC(cam_debug, "enable verbose debug messages");

#define dprintk if (dvb_ca_en50221_debug) printk

#define INIT_TIMEOUT_SECS 10

#define HOST_LINK_BUF_SIZE 0x200

#define RX_BUFFER_SIZE 65535

#define MAX_RX_PACKETS_PER_ITERATION 10

#define CTRLIF_DATA      0
#define CTRLIF_COMMAND   1
#define CTRLIF_STATUS    1
#define CTRLIF_SIZE_LOW  2
#define CTRLIF_SIZE_HIGH 3

#define CMDREG_HC        1    /* Host control */
#define CMDREG_SW        2    /* Size write */
#define CMDREG_SR        4    /* Size read */
#define CMDREG_RS        8    /* Reset interface */
#define CMDREG_FRIE   0x40    /* Enable FR interrupt */
#define CMDREG_DAIE   0x80    /* Enable DA interrupt */
#define IRQEN (CMDREG_DAIE)

#define STATUSREG_RE     1    /* read error */
#define STATUSREG_WE     2    /* write error */
#define STATUSREG_FR  0x40    /* module free */
#define STATUSREG_DA  0x80    /* data available */
#define STATUSREG_TXERR (STATUSREG_RE|STATUSREG_WE)   /* general transfer error */


#define DVB_CA_SLOTSTATE_NONE           0
#define DVB_CA_SLOTSTATE_UNINITIALISED  1
#define DVB_CA_SLOTSTATE_RUNNING        2
#define DVB_CA_SLOTSTATE_INVALID        3
#define DVB_CA_SLOTSTATE_WAITREADY      4
#define DVB_CA_SLOTSTATE_VALIDATE       5
#define DVB_CA_SLOTSTATE_WAITFR         6
#define DVB_CA_SLOTSTATE_LINKINIT       7


/* Information on a CA slot */
struct dvb_ca_slot {

      /* current state of the CAM */
      int slot_state;

      /* Number of CAMCHANGES that have occurred since last processing */
      atomic_t camchange_count;

      /* Type of last CAMCHANGE */
      int camchange_type;

      /* base address of CAM config */
      u32 config_base;

      /* value to write into Config Control register */
      u8 config_option;

      /* if 1, the CAM supports DA IRQs */
      u8 da_irq_supported:1;

      /* size of the buffer to use when talking to the CAM */
      int link_buf_size;

      /* buffer for incoming packets */
      struct dvb_ringbuffer rx_buffer;

      /* timer used during various states of the slot */
      unsigned long timeout;
};

/* Private CA-interface information */
struct dvb_ca_private {

      /* pointer back to the public data structure */
      struct dvb_ca_en50221 *pub;

      /* the DVB device */
      struct dvb_device *dvbdev;

      /* Flags describing the interface (DVB_CA_FLAG_*) */
      u32 flags;

      /* number of slots supported by this CA interface */
      unsigned int slot_count;

      /* information on each slot */
      struct dvb_ca_slot *slot_info;

      /* wait queues for read() and write() operations */
      wait_queue_head_t wait_queue;

      /* PID of the monitoring thread */
      struct task_struct *thread;

      /* Flag indicating if the CA device is open */
      unsigned int open:1;

      /* Flag indicating the thread should wake up now */
      unsigned int wakeup:1;

      /* Delay the main thread should use */
      unsigned long delay;

      /* Slot to start looking for data to read from in the next user-space read operation */
      int next_read_slot;
};

static void dvb_ca_en50221_thread_wakeup(struct dvb_ca_private *ca);
static int dvb_ca_en50221_read_data(struct dvb_ca_private *ca, int slot, u8 * ebuf, int ecount);
static int dvb_ca_en50221_write_data(struct dvb_ca_private *ca, int slot, u8 * ebuf, int ecount);


/**
 * Safely find needle in haystack.
 *
 * @param haystack Buffer to look in.
 * @param hlen Number of bytes in haystack.
 * @param needle Buffer to find.
 * @param nlen Number of bytes in needle.
 * @return Pointer into haystack needle was found at, or NULL if not found.
 */
static char *findstr(char * haystack, int hlen, char * needle, int nlen)
{
      int i;

      if (hlen < nlen)
            return NULL;

      for (i = 0; i <= hlen - nlen; i++) {
            if (!strncmp(haystack + i, needle, nlen))
                  return haystack + i;
      }

      return NULL;
}



/* ******************************************************************************** */
/* EN50221 physical interface functions */


/**
 * Check CAM status.
 */
static int dvb_ca_en50221_check_camstatus(struct dvb_ca_private *ca, int slot)
{
      int slot_status;
      int cam_present_now;
      int cam_changed;

      /* IRQ mode */
      if (ca->flags & DVB_CA_EN50221_FLAG_IRQ_CAMCHANGE) {
            return (atomic_read(&ca->slot_info[slot].camchange_count) != 0);
      }

      /* poll mode */
      slot_status = ca->pub->poll_slot_status(ca->pub, slot, ca->open);

      cam_present_now = (slot_status & DVB_CA_EN50221_POLL_CAM_PRESENT) ? 1 : 0;
      cam_changed = (slot_status & DVB_CA_EN50221_POLL_CAM_CHANGED) ? 1 : 0;
      if (!cam_changed) {
            int cam_present_old = (ca->slot_info[slot].slot_state != DVB_CA_SLOTSTATE_NONE);
            cam_changed = (cam_present_now != cam_present_old);
      }

      if (cam_changed) {
            if (!cam_present_now) {
                  ca->slot_info[slot].camchange_type = DVB_CA_EN50221_CAMCHANGE_REMOVED;
            } else {
                  ca->slot_info[slot].camchange_type = DVB_CA_EN50221_CAMCHANGE_INSERTED;
            }
            atomic_set(&ca->slot_info[slot].camchange_count, 1);
      } else {
            if ((ca->slot_info[slot].slot_state == DVB_CA_SLOTSTATE_WAITREADY) &&
                (slot_status & DVB_CA_EN50221_POLL_CAM_READY)) {
                  // move to validate state if reset is completed
                  ca->slot_info[slot].slot_state = DVB_CA_SLOTSTATE_VALIDATE;
            }
      }

      return cam_changed;
}


/**
 * Wait for flags to become set on the STATUS register on a CAM interface,
 * checking for errors and timeout.
 *
 * @param ca CA instance.
 * @param slot Slot on interface.
 * @param waitfor Flags to wait for.
 * @param timeout_ms Timeout in milliseconds.
 *
 * @return 0 on success, nonzero on error.
 */
static int dvb_ca_en50221_wait_if_status(struct dvb_ca_private *ca, int slot,
                               u8 waitfor, int timeout_hz)
{
      unsigned long timeout;
      unsigned long start;

      dprintk("%s\n", __FUNCTION__);

      /* loop until timeout elapsed */
      start = jiffies;
      timeout = jiffies + timeout_hz;
      while (1) {
            /* read the status and check for error */
            int res = ca->pub->read_cam_control(ca->pub, slot, CTRLIF_STATUS);
            if (res < 0)
                  return -EIO;

            /* if we got the flags, it was successful! */
            if (res & waitfor) {
                  dprintk("%s succeeded timeout:%lu\n", __FUNCTION__, jiffies - start);
                  return 0;
            }

            /* check for timeout */
            if (time_after(jiffies, timeout)) {
                  break;
            }

            /* wait for a bit */
            msleep(1);
      }

      dprintk("%s failed timeout:%lu\n", __FUNCTION__, jiffies - start);

      /* if we get here, we've timed out */
      return -ETIMEDOUT;
}


/**
 * Initialise the link layer connection to a CAM.
 *
 * @param ca CA instance.
 * @param slot Slot id.
 *
 * @return 0 on success, nonzero on failure.
 */
static int dvb_ca_en50221_link_init(struct dvb_ca_private *ca, int slot)
{
      int ret;
      int buf_size;
      u8 buf[2];

      dprintk("%s\n", __FUNCTION__);

      /* we'll be determining these during this function */
      ca->slot_info[slot].da_irq_supported = 0;

      /* set the host link buffer size temporarily. it will be overwritten with the
       * real negotiated size later. */
      ca->slot_info[slot].link_buf_size = 2;

      /* read the buffer size from the CAM */
      if ((ret = ca->pub->write_cam_control(ca->pub, slot, CTRLIF_COMMAND, IRQEN | CMDREG_SR)) != 0)
            return ret;
      if ((ret = dvb_ca_en50221_wait_if_status(ca, slot, STATUSREG_DA, HZ / 10)) != 0)
            return ret;
      if ((ret = dvb_ca_en50221_read_data(ca, slot, buf, 2)) != 2)
            return -EIO;
      if ((ret = ca->pub->write_cam_control(ca->pub, slot, CTRLIF_COMMAND, IRQEN)) != 0)
            return ret;

      /* store it, and choose the minimum of our buffer and the CAM's buffer size */
      buf_size = (buf[0] << 8) | buf[1];
      if (buf_size > HOST_LINK_BUF_SIZE)
            buf_size = HOST_LINK_BUF_SIZE;
      ca->slot_info[slot].link_buf_size = buf_size;
      buf[0] = buf_size >> 8;
      buf[1] = buf_size & 0xff;
      dprintk("Chosen link buffer size of %i\n", buf_size);

      /* write the buffer size to the CAM */
      if ((ret = ca->pub->write_cam_control(ca->pub, slot, CTRLIF_COMMAND, IRQEN | CMDREG_SW)) != 0)
            return ret;
      if ((ret = dvb_ca_en50221_wait_if_status(ca, slot, STATUSREG_FR, HZ / 10)) != 0)
            return ret;
      if ((ret = dvb_ca_en50221_write_data(ca, slot, buf, 2)) != 2)
            return -EIO;
      if ((ret = ca->pub->write_cam_control(ca->pub, slot, CTRLIF_COMMAND, IRQEN)) != 0)
            return ret;

      /* success */
      return 0;
}

/**
 * Read a tuple from attribute memory.
 *
 * @param ca CA instance.
 * @param slot Slot id.
 * @param address Address to read from. Updated.
 * @param tupleType Tuple id byte. Updated.
 * @param tupleLength Tuple length. Updated.
 * @param tuple Dest buffer for tuple (must be 256 bytes). Updated.
 *
 * @return 0 on success, nonzero on error.
 */
static int dvb_ca_en50221_read_tuple(struct dvb_ca_private *ca, int slot,
                             int *address, int *tupleType, int *tupleLength, u8 * tuple)
{
      int i;
      int _tupleType;
      int _tupleLength;
      int _address = *address;

      /* grab the next tuple length and type */
      if ((_tupleType = ca->pub->read_attribute_mem(ca->pub, slot, _address)) < 0)
            return _tupleType;
      if (_tupleType == 0xff) {
            dprintk("END OF CHAIN TUPLE type:0x%x\n", _tupleType);
            *address += 2;
            *tupleType = _tupleType;
            *tupleLength = 0;
            return 0;
      }
      if ((_tupleLength = ca->pub->read_attribute_mem(ca->pub, slot, _address + 2)) < 0)
            return _tupleLength;
      _address += 4;

      dprintk("TUPLE type:0x%x length:%i\n", _tupleType, _tupleLength);

      /* read in the whole tuple */
      for (i = 0; i < _tupleLength; i++) {
            tuple[i] = ca->pub->read_attribute_mem(ca->pub, slot, _address + (i * 2));
            dprintk("  0x%02x: 0x%02x %c\n",
                  i, tuple[i] & 0xff,
                  ((tuple[i] > 31) && (tuple[i] < 127)) ? tuple[i] : '.');
      }
      _address += (_tupleLength * 2);

      // success
      *tupleType = _tupleType;
      *tupleLength = _tupleLength;
      *address = _address;
      return 0;
}


/**
 * Parse attribute memory of a CAM module, extracting Config register, and checking
 * it is a DVB CAM module.
 *
 * @param ca CA instance.
 * @param slot Slot id.
 *
 * @return 0 on success, <0 on failure.
 */
static int dvb_ca_en50221_parse_attributes(struct dvb_ca_private *ca, int slot)
{
      int address = 0;
      int tupleLength;
      int tupleType;
      u8 tuple[257];
      char *dvb_str;
      int rasz;
      int status;
      int got_cftableentry = 0;
      int end_chain = 0;
      int i;
      u16 manfid = 0;
      u16 devid = 0;


      // CISTPL_DEVICE_0A
      if ((status =
           dvb_ca_en50221_read_tuple(ca, slot, &address, &tupleType, &tupleLength, tuple)) < 0)
            return status;
      if (tupleType != 0x1D)
            return -EINVAL;



      // CISTPL_DEVICE_0C
      if ((status =
           dvb_ca_en50221_read_tuple(ca, slot, &address, &tupleType, &tupleLength, tuple)) < 0)
            return status;
      if (tupleType != 0x1C)
            return -EINVAL;



      // CISTPL_VERS_1
      if ((status =
           dvb_ca_en50221_read_tuple(ca, slot, &address, &tupleType, &tupleLength, tuple)) < 0)
            return status;
      if (tupleType != 0x15)
            return -EINVAL;



      // CISTPL_MANFID
      if ((status = dvb_ca_en50221_read_tuple(ca, slot, &address, &tupleType,
                                    &tupleLength, tuple)) < 0)
            return status;
      if (tupleType != 0x20)
            return -EINVAL;
      if (tupleLength != 4)
            return -EINVAL;
      manfid = (tuple[1] << 8) | tuple[0];
      devid = (tuple[3] << 8) | tuple[2];



      // CISTPL_CONFIG
      if ((status = dvb_ca_en50221_read_tuple(ca, slot, &address, &tupleType,
                                    &tupleLength, tuple)) < 0)
            return status;
      if (tupleType != 0x1A)
            return -EINVAL;
      if (tupleLength < 3)
            return -EINVAL;

      /* extract the configbase */
      rasz = tuple[0] & 3;
      if (tupleLength < (3 + rasz + 14))
            return -EINVAL;
      ca->slot_info[slot].config_base = 0;
      for (i = 0; i < rasz + 1; i++) {
            ca->slot_info[slot].config_base |= (tuple[2 + i] << (8 * i));
      }

      /* check it contains the correct DVB string */
      dvb_str = findstr((char *)tuple, tupleLength, "DVB_CI_V", 8);
      if (dvb_str == NULL)
            return -EINVAL;
      if (tupleLength < ((dvb_str - (char *) tuple) + 12))
            return -EINVAL;

      /* is it a version we support? */
      if (strncmp(dvb_str + 8, "1.00", 4)) {
            printk("dvb_ca adapter %d: Unsupported DVB CAM module version %c%c%c%c\n",
                   ca->dvbdev->adapter->num, dvb_str[8], dvb_str[9], dvb_str[10], dvb_str[11]);
            return -EINVAL;
      }

      /* process the CFTABLE_ENTRY tuples, and any after those */
      while ((!end_chain) && (address < 0x1000)) {
            if ((status = dvb_ca_en50221_read_tuple(ca, slot, &address, &tupleType,
                                          &tupleLength, tuple)) < 0)
                  return status;
            switch (tupleType) {
            case 0x1B:  // CISTPL_CFTABLE_ENTRY
                  if (tupleLength < (2 + 11 + 17))
                        break;

                  /* if we've already parsed one, just use it */
                  if (got_cftableentry)
                        break;

                  /* get the config option */
                  ca->slot_info[slot].config_option = tuple[0] & 0x3f;

                  /* OK, check it contains the correct strings */
                  if ((findstr((char *)tuple, tupleLength, "DVB_HOST", 8) == NULL) ||
                      (findstr((char *)tuple, tupleLength, "DVB_CI_MODULE", 13) == NULL))
                        break;

                  got_cftableentry = 1;
                  break;

            case 0x14:  // CISTPL_NO_LINK
                  break;

            case 0xFF:  // CISTPL_END
                  end_chain = 1;
                  break;

            default:    /* Unknown tuple type - just skip this tuple and move to the next one */
                  dprintk("dvb_ca: Skipping unknown tuple type:0x%x length:0x%x\n", tupleType,
                        tupleLength);
                  break;
            }
      }

      if ((address > 0x1000) || (!got_cftableentry))
            return -EINVAL;

      dprintk("Valid DVB CAM detected MANID:%x DEVID:%x CONFIGBASE:0x%x CONFIGOPTION:0x%x\n",
            manfid, devid, ca->slot_info[slot].config_base, ca->slot_info[slot].config_option);

      // success!
      return 0;
}


/**
 * Set CAM's configoption correctly.
 *
 * @param ca CA instance.
 * @param slot Slot containing the CAM.
 */
static int dvb_ca_en50221_set_configoption(struct dvb_ca_private *ca, int slot)
{
      int configoption;

      dprintk("%s\n", __FUNCTION__);

      /* set the config option */
      ca->pub->write_attribute_mem(ca->pub, slot,
                             ca->slot_info[slot].config_base,
                             ca->slot_info[slot].config_option);

      /* check it */
      configoption = ca->pub->read_attribute_mem(ca->pub, slot, ca->slot_info[slot].config_base);
      dprintk("Set configoption 0x%x, read configoption 0x%x\n",
            ca->slot_info[slot].config_option, configoption & 0x3f);

      /* fine! */
      return 0;

}


/**
 * This function talks to an EN50221 CAM control interface. It reads a buffer of
 * data from the CAM. The data can either be stored in a supplied buffer, or
 * automatically be added to the slot's rx_buffer.
 *
 * @param ca CA instance.
 * @param slot Slot to read from.
 * @param ebuf If non-NULL, the data will be written to this buffer. If NULL,
 * the data will be added into the buffering system as a normal fragment.
 * @param ecount Size of ebuf. Ignored if ebuf is NULL.
 *
 * @return Number of bytes read, or < 0 on error
 */
static int dvb_ca_en50221_read_data(struct dvb_ca_private *ca, int slot, u8 * ebuf, int ecount)
{
      int bytes_read;
      int status;
      u8 buf[HOST_LINK_BUF_SIZE];
      int i;

      dprintk("%s\n", __FUNCTION__);

      /* check if we have space for a link buf in the rx_buffer */
      if (ebuf == NULL) {
            int buf_free;

            if (ca->slot_info[slot].rx_buffer.data == NULL) {
                  status = -EIO;
                  goto exit;
            }
            buf_free = dvb_ringbuffer_free(&ca->slot_info[slot].rx_buffer);

            if (buf_free < (ca->slot_info[slot].link_buf_size + DVB_RINGBUFFER_PKTHDRSIZE)) {
                  status = -EAGAIN;
                  goto exit;
            }
      }

      /* check if there is data available */
      if ((status = ca->pub->read_cam_control(ca->pub, slot, CTRLIF_STATUS)) < 0)
            goto exit;
      if (!(status & STATUSREG_DA)) {
            /* no data */
            status = 0;
            goto exit;
      }

      /* read the amount of data */
      if ((status = ca->pub->read_cam_control(ca->pub, slot, CTRLIF_SIZE_HIGH)) < 0)
            goto exit;
      bytes_read = status << 8;
      if ((status = ca->pub->read_cam_control(ca->pub, slot, CTRLIF_SIZE_LOW)) < 0)
            goto exit;
      bytes_read |= status;

      /* check it will fit */
      if (ebuf == NULL) {
            if (bytes_read > ca->slot_info[slot].link_buf_size) {
                  printk("dvb_ca adapter %d: CAM tried to send a buffer larger than the link buffer size (%i > %i)!\n",
                         ca->dvbdev->adapter->num, bytes_read, ca->slot_info[slot].link_buf_size);
                  ca->slot_info[slot].slot_state = DVB_CA_SLOTSTATE_LINKINIT;
                  status = -EIO;
                  goto exit;
            }
            if (bytes_read < 2) {
                  printk("dvb_ca adapter %d: CAM sent a buffer that was less than 2 bytes!\n",
                         ca->dvbdev->adapter->num);
                  ca->slot_info[slot].slot_state = DVB_CA_SLOTSTATE_LINKINIT;
                  status = -EIO;
                  goto exit;
            }
      } else {
            if (bytes_read > ecount) {
                  printk("dvb_ca adapter %d: CAM tried to send a buffer larger than the ecount size!\n",
                         ca->dvbdev->adapter->num);
                  status = -EIO;
                  goto exit;
            }
      }

      /* fill the buffer */
      for (i = 0; i < bytes_read; i++) {
            /* read byte and check */
            if ((status = ca->pub->read_cam_control(ca->pub, slot, CTRLIF_DATA)) < 0)
                  goto exit;

            /* OK, store it in the buffer */
            buf[i] = status;
      }

      /* check for read error (RE should now be 0) */
      if ((status = ca->pub->read_cam_control(ca->pub, slot, CTRLIF_STATUS)) < 0)
            goto exit;
      if (status & STATUSREG_RE) {
            ca->slot_info[slot].slot_state = DVB_CA_SLOTSTATE_LINKINIT;
            status = -EIO;
            goto exit;
      }

      /* OK, add it to the receive buffer, or copy into external buffer if supplied */
      if (ebuf == NULL) {
            if (ca->slot_info[slot].rx_buffer.data == NULL) {
                  status = -EIO;
                  goto exit;
            }
            dvb_ringbuffer_pkt_write(&ca->slot_info[slot].rx_buffer, buf, bytes_read);
      } else {
            memcpy(ebuf, buf, bytes_read);
      }

      dprintk("Received CA packet for slot %i connection id 0x%x last_frag:%i size:0x%x\n", slot,
            buf[0], (buf[1] & 0x80) == 0, bytes_read);

      /* wake up readers when a last_fragment is received */
      if ((buf[1] & 0x80) == 0x00) {
            wake_up_interruptible(&ca->wait_queue);
      }
      status = bytes_read;

exit:
      return status;
}


/**
 * This function talks to an EN50221 CAM control interface. It writes a buffer of data
 * to a CAM.
 *
 * @param ca CA instance.
 * @param slot Slot to write to.
 * @param ebuf The data in this buffer is treated as a complete link-level packet to
 * be written.
 * @param count Size of ebuf.
 *
 * @return Number of bytes written, or < 0 on error.
 */
static int dvb_ca_en50221_write_data(struct dvb_ca_private *ca, int slot, u8 * buf, int bytes_write)
{
      int status;
      int i;

      dprintk("%s\n", __FUNCTION__);


      // sanity check
      if (bytes_write > ca->slot_info[slot].link_buf_size)
            return -EINVAL;

      /* check if interface is actually waiting for us to read from it, or if a read is in progress */
      if ((status = ca->pub->read_cam_control(ca->pub, slot, CTRLIF_STATUS)) < 0)
            goto exitnowrite;
      if (status & (STATUSREG_DA | STATUSREG_RE)) {
            status = -EAGAIN;
            goto exitnowrite;
      }

      /* OK, set HC bit */
      if ((status = ca->pub->write_cam_control(ca->pub, slot, CTRLIF_COMMAND,
                                     IRQEN | CMDREG_HC)) != 0)
            goto exit;

      /* check if interface is still free */
      if ((status = ca->pub->read_cam_control(ca->pub, slot, CTRLIF_STATUS)) < 0)
            goto exit;
      if (!(status & STATUSREG_FR)) {
            /* it wasn't free => try again later */
            status = -EAGAIN;
            goto exit;
      }

      /* send the amount of data */
      if ((status = ca->pub->write_cam_control(ca->pub, slot, CTRLIF_SIZE_HIGH, bytes_write >> 8)) != 0)
            goto exit;
      if ((status = ca->pub->write_cam_control(ca->pub, slot, CTRLIF_SIZE_LOW,
                                     bytes_write & 0xff)) != 0)
            goto exit;

      /* send the buffer */
      for (i = 0; i < bytes_write; i++) {
            if ((status = ca->pub->write_cam_control(ca->pub, slot, CTRLIF_DATA, buf[i])) != 0)
                  goto exit;
      }

      /* check for write error (WE should now be 0) */
      if ((status = ca->pub->read_cam_control(ca->pub, slot, CTRLIF_STATUS)) < 0)
            goto exit;
      if (status & STATUSREG_WE) {
            ca->slot_info[slot].slot_state = DVB_CA_SLOTSTATE_LINKINIT;
            status = -EIO;
            goto exit;
      }
      status = bytes_write;

      dprintk("Wrote CA packet for slot %i, connection id 0x%x last_frag:%i size:0x%x\n", slot,
            buf[0], (buf[1] & 0x80) == 0, bytes_write);

exit:
      ca->pub->write_cam_control(ca->pub, slot, CTRLIF_COMMAND, IRQEN);

exitnowrite:
      return status;
}
EXPORT_SYMBOL(dvb_ca_en50221_camchange_irq);



/* ******************************************************************************** */
/* EN50221 higher level functions */


/**
 * A CAM has been removed => shut it down.
 *
 * @param ca CA instance.
 * @param slot Slot to shut down.
 */
static int dvb_ca_en50221_slot_shutdown(struct dvb_ca_private *ca, int slot)
{
      dprintk("%s\n", __FUNCTION__);

      ca->pub->slot_shutdown(ca->pub, slot);
      ca->slot_info[slot].slot_state = DVB_CA_SLOTSTATE_NONE;

      /* need to wake up all processes to check if they're now
         trying to write to a defunct CAM */
      wake_up_interruptible(&ca->wait_queue);

      dprintk("Slot %i shutdown\n", slot);

      /* success */
      return 0;
}
EXPORT_SYMBOL(dvb_ca_en50221_camready_irq);


/**
 * A CAMCHANGE IRQ has occurred.
 *
 * @param ca CA instance.
 * @param slot Slot concerned.
 * @param change_type One of the DVB_CA_CAMCHANGE_* values.
 */
void dvb_ca_en50221_camchange_irq(struct dvb_ca_en50221 *pubca, int slot, int change_type)
{
      struct dvb_ca_private *ca = pubca->private;

      dprintk("CAMCHANGE IRQ slot:%i change_type:%i\n", slot, change_type);

      switch (change_type) {
      case DVB_CA_EN50221_CAMCHANGE_REMOVED:
      case DVB_CA_EN50221_CAMCHANGE_INSERTED:
            break;

      default:
            return;
      }

      ca->slot_info[slot].camchange_type = change_type;
      atomic_inc(&ca->slot_info[slot].camchange_count);
      dvb_ca_en50221_thread_wakeup(ca);
}
EXPORT_SYMBOL(dvb_ca_en50221_frda_irq);


/**
 * A CAMREADY IRQ has occurred.
 *
 * @param ca CA instance.
 * @param slot Slot concerned.
 */
void dvb_ca_en50221_camready_irq(struct dvb_ca_en50221 *pubca, int slot)
{
      struct dvb_ca_private *ca = pubca->private;

      dprintk("CAMREADY IRQ slot:%i\n", slot);

      if (ca->slot_info[slot].slot_state == DVB_CA_SLOTSTATE_WAITREADY) {
            ca->slot_info[slot].slot_state = DVB_CA_SLOTSTATE_VALIDATE;
            dvb_ca_en50221_thread_wakeup(ca);
      }
}


/**
 * An FR or DA IRQ has occurred.
 *
 * @param ca CA instance.
 * @param slot Slot concerned.
 */
void dvb_ca_en50221_frda_irq(struct dvb_ca_en50221 *pubca, int slot)
{
      struct dvb_ca_private *ca = pubca->private;
      int flags;

      dprintk("FR/DA IRQ slot:%i\n", slot);

      switch (ca->slot_info[slot].slot_state) {
      case DVB_CA_SLOTSTATE_LINKINIT:
            flags = ca->pub->read_cam_control(pubca, slot, CTRLIF_STATUS);
            if (flags & STATUSREG_DA) {
                  dprintk("CAM supports DA IRQ\n");
                  ca->slot_info[slot].da_irq_supported = 1;
            }
            break;

      case DVB_CA_SLOTSTATE_RUNNING:
            if (ca->open)
                  dvb_ca_en50221_thread_wakeup(ca);
            break;
      }
}



/* ******************************************************************************** */
/* EN50221 thread functions */

/**
 * Wake up the DVB CA thread
 *
 * @param ca CA instance.
 */
static void dvb_ca_en50221_thread_wakeup(struct dvb_ca_private *ca)
{

      dprintk("%s\n", __FUNCTION__);

      ca->wakeup = 1;
      mb();
      wake_up_process(ca->thread);
}

/**
 * Update the delay used by the thread.
 *
 * @param ca CA instance.
 */
static void dvb_ca_en50221_thread_update_delay(struct dvb_ca_private *ca)
{
      int delay;
      int curdelay = 100000000;
      int slot;

      for (slot = 0; slot < ca->slot_count; slot++) {
            switch (ca->slot_info[slot].slot_state) {
            default:
            case DVB_CA_SLOTSTATE_NONE:
            case DVB_CA_SLOTSTATE_INVALID:
                  delay = HZ * 60;
                  if (!(ca->flags & DVB_CA_EN50221_FLAG_IRQ_CAMCHANGE)) {
                        delay = HZ / 10;
                  }
                  break;

            case DVB_CA_SLOTSTATE_UNINITIALISED:
            case DVB_CA_SLOTSTATE_WAITREADY:
            case DVB_CA_SLOTSTATE_VALIDATE:
            case DVB_CA_SLOTSTATE_WAITFR:
            case DVB_CA_SLOTSTATE_LINKINIT:
                  delay = HZ / 10;
                  break;

            case DVB_CA_SLOTSTATE_RUNNING:
                  delay = HZ * 60;
                  if (!(ca->flags & DVB_CA_EN50221_FLAG_IRQ_CAMCHANGE)) {
                        delay = HZ / 10;
                  }
                  if (ca->open) {
                        if ((!ca->slot_info[slot].da_irq_supported) ||
                            (!(ca->flags & DVB_CA_EN50221_FLAG_IRQ_DA))) {
                              delay = HZ / 10;
                        }
                  }
                  break;
            }

            if (delay < curdelay)
                  curdelay = delay;
      }

      ca->delay = curdelay;
}



/**
 * Kernel thread which monitors CA slots for CAM changes, and performs data transfers.
 */
static int dvb_ca_en50221_thread(void *data)
{
      struct dvb_ca_private *ca = data;
      int slot;
      int flags;
      int status;
      int pktcount;
      void *rxbuf;

      dprintk("%s\n", __FUNCTION__);

      /* choose the correct initial delay */
      dvb_ca_en50221_thread_update_delay(ca);

      /* main loop */
      while (!kthread_should_stop()) {
            /* sleep for a bit */
            if (!ca->wakeup) {
                  set_current_state(TASK_INTERRUPTIBLE);
                  schedule_timeout(ca->delay);
                  if (kthread_should_stop())
                        return 0;
            }
            ca->wakeup = 0;

            /* go through all the slots processing them */
            for (slot = 0; slot < ca->slot_count; slot++) {

                  // check the cam status + deal with CAMCHANGEs
                  while (dvb_ca_en50221_check_camstatus(ca, slot)) {
                        /* clear down an old CI slot if necessary */
                        if (ca->slot_info[slot].slot_state != DVB_CA_SLOTSTATE_NONE)
                              dvb_ca_en50221_slot_shutdown(ca, slot);

                        /* if a CAM is NOW present, initialise it */
                        if (ca->slot_info[slot].camchange_type == DVB_CA_EN50221_CAMCHANGE_INSERTED) {
                              ca->slot_info[slot].slot_state = DVB_CA_SLOTSTATE_UNINITIALISED;
                        }

                        /* we've handled one CAMCHANGE */
                        dvb_ca_en50221_thread_update_delay(ca);
                        atomic_dec(&ca->slot_info[slot].camchange_count);
                  }

                  // CAM state machine
                  switch (ca->slot_info[slot].slot_state) {
                  case DVB_CA_SLOTSTATE_NONE:
                  case DVB_CA_SLOTSTATE_INVALID:
                        // no action needed
                        break;

                  case DVB_CA_SLOTSTATE_UNINITIALISED:
                        ca->slot_info[slot].slot_state = DVB_CA_SLOTSTATE_WAITREADY;
                        ca->pub->slot_reset(ca->pub, slot);
                        ca->slot_info[slot].timeout = jiffies + (INIT_TIMEOUT_SECS * HZ);
                        break;

                  case DVB_CA_SLOTSTATE_WAITREADY:
                        if (time_after(jiffies, ca->slot_info[slot].timeout)) {
                              printk("dvb_ca adaptor %d: PC card did not respond :(\n",
                                     ca->dvbdev->adapter->num);
                              ca->slot_info[slot].slot_state = DVB_CA_SLOTSTATE_INVALID;
                              dvb_ca_en50221_thread_update_delay(ca);
                              break;
                        }
                        // no other action needed; will automatically change state when ready
                        break;

                  case DVB_CA_SLOTSTATE_VALIDATE:
                        if (dvb_ca_en50221_parse_attributes(ca, slot) != 0) {
                              /* we need this extra check for annoying interfaces like the budget-av */
                              if ((!(ca->flags & DVB_CA_EN50221_FLAG_IRQ_CAMCHANGE)) &&
                                  (ca->pub->poll_slot_status)) {
                                    int status = ca->pub->poll_slot_status(ca->pub, slot, 0);
                                    if (!(status & DVB_CA_EN50221_POLL_CAM_PRESENT)) {
                                          ca->slot_info[slot].slot_state = DVB_CA_SLOTSTATE_NONE;
                                          dvb_ca_en50221_thread_update_delay(ca);
                                          break;
                                    }
                              }

                              printk("dvb_ca adapter %d: Invalid PC card inserted :(\n",
                                     ca->dvbdev->adapter->num);
                              ca->slot_info[slot].slot_state = DVB_CA_SLOTSTATE_INVALID;
                              dvb_ca_en50221_thread_update_delay(ca);
                              break;
                        }
                        if (dvb_ca_en50221_set_configoption(ca, slot) != 0) {
                              printk("dvb_ca adapter %d: Unable to initialise CAM :(\n",
                                     ca->dvbdev->adapter->num);
                              ca->slot_info[slot].slot_state = DVB_CA_SLOTSTATE_INVALID;
                              dvb_ca_en50221_thread_update_delay(ca);
                              break;
                        }
                        if (ca->pub->write_cam_control(ca->pub, slot,
                                                 CTRLIF_COMMAND, CMDREG_RS) != 0) {
                              printk("dvb_ca adapter %d: Unable to reset CAM IF\n",
                                     ca->dvbdev->adapter->num);
                              ca->slot_info[slot].slot_state = DVB_CA_SLOTSTATE_INVALID;
                              dvb_ca_en50221_thread_update_delay(ca);
                              break;
                        }
                        dprintk("DVB CAM validated successfully\n");

                        ca->slot_info[slot].timeout = jiffies + (INIT_TIMEOUT_SECS * HZ);
                        ca->slot_info[slot].slot_state = DVB_CA_SLOTSTATE_WAITFR;
                        ca->wakeup = 1;
                        break;

                  case DVB_CA_SLOTSTATE_WAITFR:
                        if (time_after(jiffies, ca->slot_info[slot].timeout)) {
                              printk("dvb_ca adapter %d: DVB CAM did not respond :(\n",
                                     ca->dvbdev->adapter->num);
                              ca->slot_info[slot].slot_state = DVB_CA_SLOTSTATE_INVALID;
                              dvb_ca_en50221_thread_update_delay(ca);
                              break;
                        }

                        flags = ca->pub->read_cam_control(ca->pub, slot, CTRLIF_STATUS);
                        if (flags & STATUSREG_FR) {
                              ca->slot_info[slot].slot_state = DVB_CA_SLOTSTATE_LINKINIT;
                              ca->wakeup = 1;
                        }
                        break;

                  case DVB_CA_SLOTSTATE_LINKINIT:
                        if (dvb_ca_en50221_link_init(ca, slot) != 0) {
                              /* we need this extra check for annoying interfaces like the budget-av */
                              if ((!(ca->flags & DVB_CA_EN50221_FLAG_IRQ_CAMCHANGE)) &&
                                  (ca->pub->poll_slot_status)) {
                                    int status = ca->pub->poll_slot_status(ca->pub, slot, 0);
                                    if (!(status & DVB_CA_EN50221_POLL_CAM_PRESENT)) {
                                          ca->slot_info[slot].slot_state = DVB_CA_SLOTSTATE_NONE;
                                          dvb_ca_en50221_thread_update_delay(ca);
                                          break;
                                    }
                              }

                              printk("dvb_ca adapter %d: DVB CAM link initialisation failed :(\n", ca->dvbdev->adapter->num);
                              ca->slot_info[slot].slot_state = DVB_CA_SLOTSTATE_INVALID;
                              dvb_ca_en50221_thread_update_delay(ca);
                              break;
                        }

                        if (ca->slot_info[slot].rx_buffer.data == NULL) {
                              rxbuf = vmalloc(RX_BUFFER_SIZE);
                              if (rxbuf == NULL) {
                                    printk("dvb_ca adapter %d: Unable to allocate CAM rx buffer :(\n", ca->dvbdev->adapter->num);
                                    ca->slot_info[slot].slot_state = DVB_CA_SLOTSTATE_INVALID;
                                    dvb_ca_en50221_thread_update_delay(ca);
                                    break;
                              }
                              dvb_ringbuffer_init(&ca->slot_info[slot].rx_buffer, rxbuf, RX_BUFFER_SIZE);
                        }

                        ca->pub->slot_ts_enable(ca->pub, slot);
                        ca->slot_info[slot].slot_state = DVB_CA_SLOTSTATE_RUNNING;
                        dvb_ca_en50221_thread_update_delay(ca);
                        printk("dvb_ca adapter %d: DVB CAM detected and initialised successfully\n", ca->dvbdev->adapter->num);
                        break;

                  case DVB_CA_SLOTSTATE_RUNNING:
                        if (!ca->open)
                              continue;

                        // poll slots for data
                        pktcount = 0;
                        while ((status = dvb_ca_en50221_read_data(ca, slot, NULL, 0)) > 0) {
                              if (!ca->open)
                                    break;

                              /* if a CAMCHANGE occurred at some point, do not do any more processing of this slot */
                              if (dvb_ca_en50221_check_camstatus(ca, slot)) {
                                    // we dont want to sleep on the next iteration so we can handle the cam change
                                    ca->wakeup = 1;
                                    break;
                              }

                              /* check if we've hit our limit this time */
                              if (++pktcount >= MAX_RX_PACKETS_PER_ITERATION) {
                                    // dont sleep; there is likely to be more data to read
                                    ca->wakeup = 1;
                                    break;
                              }
                        }
                        break;
                  }
            }
      }

      return 0;
}



/* ******************************************************************************** */
/* EN50221 IO interface functions */

/**
 * Real ioctl implementation.
 * NOTE: CA_SEND_MSG/CA_GET_MSG ioctls have userspace buffers passed to them.
 *
 * @param inode Inode concerned.
 * @param file File concerned.
 * @param cmd IOCTL command.
 * @param arg Associated argument.
 *
 * @return 0 on success, <0 on error.
 */
static int dvb_ca_en50221_io_do_ioctl(struct inode *inode, struct file *file,
                              unsigned int cmd, void *parg)
{
      struct dvb_device *dvbdev = file->private_data;
      struct dvb_ca_private *ca = dvbdev->priv;
      int err = 0;
      int slot;

      dprintk("%s\n", __FUNCTION__);

      switch (cmd) {
      case CA_RESET:
            for (slot = 0; slot < ca->slot_count; slot++) {
                  if (ca->slot_info[slot].slot_state != DVB_CA_SLOTSTATE_NONE) {
                        dvb_ca_en50221_slot_shutdown(ca, slot);
                        if (ca->flags & DVB_CA_EN50221_FLAG_IRQ_CAMCHANGE)
                              dvb_ca_en50221_camchange_irq(ca->pub,
                                                     slot,
                                                     DVB_CA_EN50221_CAMCHANGE_INSERTED);
                  }
            }
            ca->next_read_slot = 0;
            dvb_ca_en50221_thread_wakeup(ca);
            break;

      case CA_GET_CAP: {
            struct ca_caps *caps = parg;

            caps->slot_num = ca->slot_count;
            caps->slot_type = CA_CI_LINK;
            caps->descr_num = 0;
            caps->descr_type = 0;
            break;
      }

      case CA_GET_SLOT_INFO: {
            struct ca_slot_info *info = parg;

            if ((info->num > ca->slot_count) || (info->num < 0))
                  return -EINVAL;

            info->type = CA_CI_LINK;
            info->flags = 0;
            if ((ca->slot_info[info->num].slot_state != DVB_CA_SLOTSTATE_NONE)
                  && (ca->slot_info[info->num].slot_state != DVB_CA_SLOTSTATE_INVALID)) {
                  info->flags = CA_CI_MODULE_PRESENT;
            }
            if (ca->slot_info[info->num].slot_state == DVB_CA_SLOTSTATE_RUNNING) {
                  info->flags |= CA_CI_MODULE_READY;
            }
            break;
      }

      default:
            err = -EINVAL;
            break;
      }

      return err;
}


/**
 * Wrapper for ioctl implementation.
 *
 * @param inode Inode concerned.
 * @param file File concerned.
 * @param cmd IOCTL command.
 * @param arg Associated argument.
 *
 * @return 0 on success, <0 on error.
 */
static int dvb_ca_en50221_io_ioctl(struct inode *inode, struct file *file,
                           unsigned int cmd, unsigned long arg)
{
      return dvb_usercopy(inode, file, cmd, arg, dvb_ca_en50221_io_do_ioctl);
}


/**
 * Implementation of write() syscall.
 *
 * @param file File structure.
 * @param buf Source buffer.
 * @param count Size of source buffer.
 * @param ppos Position in file (ignored).
 *
 * @return Number of bytes read, or <0 on error.
 */
static ssize_t dvb_ca_en50221_io_write(struct file *file,
                               const char __user * buf, size_t count, loff_t * ppos)
{
      struct dvb_device *dvbdev = file->private_data;
      struct dvb_ca_private *ca = dvbdev->priv;
      u8 slot, connection_id;
      int status;
      u8 fragbuf[HOST_LINK_BUF_SIZE];
      int fragpos = 0;
      int fraglen;
      unsigned long timeout;
      int written;

      dprintk("%s\n", __FUNCTION__);

      /* Incoming packet has a 2 byte header. hdr[0] = slot_id, hdr[1] = connection_id */
      if (count < 2)
            return -EINVAL;

      /* extract slot & connection id */
      if (copy_from_user(&slot, buf, 1))
            return -EFAULT;
      if (copy_from_user(&connection_id, buf + 1, 1))
            return -EFAULT;
      buf += 2;
      count -= 2;

      /* check if the slot is actually running */
      if (ca->slot_info[slot].slot_state != DVB_CA_SLOTSTATE_RUNNING)
            return -EINVAL;

      /* fragment the packets & store in the buffer */
      while (fragpos < count) {
            fraglen = ca->slot_info[slot].link_buf_size - 2;
            if ((count - fragpos) < fraglen)
                  fraglen = count - fragpos;

            fragbuf[0] = connection_id;
            fragbuf[1] = ((fragpos + fraglen) < count) ? 0x80 : 0x00;
            if ((status = copy_from_user(fragbuf + 2, buf + fragpos, fraglen)) != 0)
                  goto exit;

            timeout = jiffies + HZ / 2;
            written = 0;
            while (!time_after(jiffies, timeout)) {
                  /* check the CAM hasn't been removed/reset in the meantime */
                  if (ca->slot_info[slot].slot_state != DVB_CA_SLOTSTATE_RUNNING) {
                        status = -EIO;
                        goto exit;
                  }

                  status = dvb_ca_en50221_write_data(ca, slot, fragbuf, fraglen + 2);
                  if (status == (fraglen + 2)) {
                        written = 1;
                        break;
                  }
                  if (status != -EAGAIN)
                        goto exit;

                  msleep(1);
            }
            if (!written) {
                  status = -EIO;
                  goto exit;
            }

            fragpos += fraglen;
      }
      status = count + 2;

exit:
      return status;
}


/**
 * Condition for waking up in dvb_ca_en50221_io_read_condition
 */
static int dvb_ca_en50221_io_read_condition(struct dvb_ca_private *ca,
                                  int *result, int *_slot)
{
      int slot;
      int slot_count = 0;
      int idx;
      size_t fraglen;
      int connection_id = -1;
      int found = 0;
      u8 hdr[2];

      slot = ca->next_read_slot;
      while ((slot_count < ca->slot_count) && (!found)) {
            if (ca->slot_info[slot].slot_state != DVB_CA_SLOTSTATE_RUNNING)
                  goto nextslot;

            if (ca->slot_info[slot].rx_buffer.data == NULL) {
                  return 0;
            }

            idx = dvb_ringbuffer_pkt_next(&ca->slot_info[slot].rx_buffer, -1, &fraglen);
            while (idx != -1) {
                  dvb_ringbuffer_pkt_read(&ca->slot_info[slot].rx_buffer, idx, 0, hdr, 2, 0);
                  if (connection_id == -1)
                        connection_id = hdr[0];
                  if ((hdr[0] == connection_id) && ((hdr[1] & 0x80) == 0)) {
                        *_slot = slot;
                        found = 1;
                        break;
                  }

                  idx = dvb_ringbuffer_pkt_next(&ca->slot_info[slot].rx_buffer, idx, &fraglen);
            }

nextslot:
            slot = (slot + 1) % ca->slot_count;
            slot_count++;
      }

      ca->next_read_slot = slot;
      return found;
}


/**
 * Implementation of read() syscall.
 *
 * @param file File structure.
 * @param buf Destination buffer.
 * @param count Size of destination buffer.
 * @param ppos Position in file (ignored).
 *
 * @return Number of bytes read, or <0 on error.
 */
static ssize_t dvb_ca_en50221_io_read(struct file *file, char __user * buf,
                              size_t count, loff_t * ppos)
{
      struct dvb_device *dvbdev = file->private_data;
      struct dvb_ca_private *ca = dvbdev->priv;
      int status;
      int result = 0;
      u8 hdr[2];
      int slot;
      int connection_id = -1;
      size_t idx, idx2;
      int last_fragment = 0;
      size_t fraglen;
      int pktlen;
      int dispose = 0;

      dprintk("%s\n", __FUNCTION__);

      /* Outgoing packet has a 2 byte header. hdr[0] = slot_id, hdr[1] = connection_id */
      if (count < 2)
            return -EINVAL;

      /* wait for some data */
      if ((status = dvb_ca_en50221_io_read_condition(ca, &result, &slot)) == 0) {

            /* if we're in nonblocking mode, exit immediately */
            if (file->f_flags & O_NONBLOCK)
                  return -EWOULDBLOCK;

            /* wait for some data */
            status = wait_event_interruptible(ca->wait_queue,
                                      dvb_ca_en50221_io_read_condition
                                      (ca, &result, &slot));
      }
      if ((status < 0) || (result < 0)) {
            if (result)
                  return result;
            return status;
      }

      idx = dvb_ringbuffer_pkt_next(&ca->slot_info[slot].rx_buffer, -1, &fraglen);
      pktlen = 2;
      do {
            if (idx == -1) {
                  printk("dvb_ca adapter %d: BUG: read packet ended before last_fragment encountered\n", ca->dvbdev->adapter->num);
                  status = -EIO;
                  goto exit;
            }

            dvb_ringbuffer_pkt_read(&ca->slot_info[slot].rx_buffer, idx, 0, hdr, 2, 0);
            if (connection_id == -1)
                  connection_id = hdr[0];
            if (hdr[0] == connection_id) {
                  if (pktlen < count) {
                        if ((pktlen + fraglen - 2) > count) {
                              fraglen = count - pktlen;
                        } else {
                              fraglen -= 2;
                        }

                        if ((status = dvb_ringbuffer_pkt_read(&ca->slot_info[slot].rx_buffer, idx, 2,
                                                      (u8 *)buf + pktlen, fraglen, 1)) < 0) {
                              goto exit;
                        }
                        pktlen += fraglen;
                  }

                  if ((hdr[1] & 0x80) == 0)
                        last_fragment = 1;
                  dispose = 1;
            }

            idx2 = dvb_ringbuffer_pkt_next(&ca->slot_info[slot].rx_buffer, idx, &fraglen);
            if (dispose)
                  dvb_ringbuffer_pkt_dispose(&ca->slot_info[slot].rx_buffer, idx);
            idx = idx2;
            dispose = 0;
      } while (!last_fragment);

      hdr[0] = slot;
      hdr[1] = connection_id;
      if ((status = copy_to_user(buf, hdr, 2)) != 0)
            goto exit;
      status = pktlen;

exit:
      return status;
}


/**
 * Implementation of file open syscall.
 *
 * @param inode Inode concerned.
 * @param file File concerned.
 *
 * @return 0 on success, <0 on failure.
 */
static int dvb_ca_en50221_io_open(struct inode *inode, struct file *file)
{
      struct dvb_device *dvbdev = file->private_data;
      struct dvb_ca_private *ca = dvbdev->priv;
      int err;
      int i;

      dprintk("%s\n", __FUNCTION__);

      if (!try_module_get(ca->pub->owner))
            return -EIO;

      err = dvb_generic_open(inode, file);
      if (err < 0) {
            module_put(ca->pub->owner);
            return err;
      }

      for (i = 0; i < ca->slot_count; i++) {

            if (ca->slot_info[i].slot_state == DVB_CA_SLOTSTATE_RUNNING) {
                  if (ca->slot_info[i].rx_buffer.data != NULL) {
                        /* it is safe to call this here without locks because
                         * ca->open == 0. Data is not read in this case */
                        dvb_ringbuffer_flush(&ca->slot_info[i].rx_buffer);
                  }
            }
      }

      ca->open = 1;
      dvb_ca_en50221_thread_update_delay(ca);
      dvb_ca_en50221_thread_wakeup(ca);

      return 0;
}


/**
 * Implementation of file close syscall.
 *
 * @param inode Inode concerned.
 * @param file File concerned.
 *
 * @return 0 on success, <0 on failure.
 */
static int dvb_ca_en50221_io_release(struct inode *inode, struct file *file)
{
      struct dvb_device *dvbdev = file->private_data;
      struct dvb_ca_private *ca = dvbdev->priv;
      int err;

      dprintk("%s\n", __FUNCTION__);

      /* mark the CA device as closed */
      ca->open = 0;
      dvb_ca_en50221_thread_update_delay(ca);

      err = dvb_generic_release(inode, file);

      module_put(ca->pub->owner);

      return err;
}


/**
 * Implementation of poll() syscall.
 *
 * @param file File concerned.
 * @param wait poll wait table.
 *
 * @return Standard poll mask.
 */
static unsigned int dvb_ca_en50221_io_poll(struct file *file, poll_table * wait)
{
      struct dvb_device *dvbdev = file->private_data;
      struct dvb_ca_private *ca = dvbdev->priv;
      unsigned int mask = 0;
      int slot;
      int result = 0;

      dprintk("%s\n", __FUNCTION__);

      if (dvb_ca_en50221_io_read_condition(ca, &result, &slot) == 1) {
            mask |= POLLIN;
      }

      /* if there is something, return now */
      if (mask)
            return mask;

      /* wait for something to happen */
      poll_wait(file, &ca->wait_queue, wait);

      if (dvb_ca_en50221_io_read_condition(ca, &result, &slot) == 1) {
            mask |= POLLIN;
      }

      return mask;
}
EXPORT_SYMBOL(dvb_ca_en50221_init);


static struct file_operations dvb_ca_fops = {
      .owner = THIS_MODULE,
      .read = dvb_ca_en50221_io_read,
      .write = dvb_ca_en50221_io_write,
      .ioctl = dvb_ca_en50221_io_ioctl,
      .open = dvb_ca_en50221_io_open,
      .release = dvb_ca_en50221_io_release,
      .poll = dvb_ca_en50221_io_poll,
};

static struct dvb_device dvbdev_ca = {
      .priv = NULL,
      .users = 1,
      .readers = 1,
      .writers = 1,
      .fops = &dvb_ca_fops,
};


/* ******************************************************************************** */
/* Initialisation/shutdown functions */


/**
 * Initialise a new DVB CA EN50221 interface device.
 *
 * @param dvb_adapter DVB adapter to attach the new CA device to.
 * @param ca The dvb_ca instance.
 * @param flags Flags describing the CA device (DVB_CA_FLAG_*).
 * @param slot_count Number of slots supported.
 *
 * @return 0 on success, nonzero on failure
 */
int dvb_ca_en50221_init(struct dvb_adapter *dvb_adapter,
                  struct dvb_ca_en50221 *pubca, int flags, int slot_count)
{
      int ret;
      struct dvb_ca_private *ca = NULL;
      int i;

      dprintk("%s\n", __FUNCTION__);

      if (slot_count < 1)
            return -EINVAL;

      /* initialise the system data */
      if ((ca = kzalloc(sizeof(struct dvb_ca_private), GFP_KERNEL)) == NULL) {
            ret = -ENOMEM;
            goto error;
      }
      ca->pub = pubca;
      ca->flags = flags;
      ca->slot_count = slot_count;
      if ((ca->slot_info = kcalloc(slot_count, sizeof(struct dvb_ca_slot), GFP_KERNEL)) == NULL) {
            ret = -ENOMEM;
            goto error;
      }
      init_waitqueue_head(&ca->wait_queue);
      ca->open = 0;
      ca->wakeup = 0;
      ca->next_read_slot = 0;
      pubca->private = ca;

      /* register the DVB device */
      ret = dvb_register_device(dvb_adapter, &ca->dvbdev, &dvbdev_ca, ca, DVB_DEVICE_CA);
      if (ret)
            goto error;

      /* now initialise each slot */
      for (i = 0; i < slot_count; i++) {
            memset(&ca->slot_info[i], 0, sizeof(struct dvb_ca_slot));
            ca->slot_info[i].slot_state = DVB_CA_SLOTSTATE_NONE;
            atomic_set(&ca->slot_info[i].camchange_count, 0);
            ca->slot_info[i].camchange_type = DVB_CA_EN50221_CAMCHANGE_REMOVED;
      }

      if (signal_pending(current)) {
            ret = -EINTR;
            goto error;
      }
      mb();

      /* create a kthread for monitoring this CA device */
      ca->thread = kthread_run(dvb_ca_en50221_thread, ca, "kdvb-ca-%i:%i",
                         ca->dvbdev->adapter->num, ca->dvbdev->id);
      if (IS_ERR(ca->thread)) {
            ret = PTR_ERR(ca->thread);
            printk("dvb_ca_init: failed to start kernel_thread (%d)\n",
                  ret);
            goto error;
      }
      return 0;

error:
      if (ca != NULL) {
            if (ca->dvbdev != NULL)
                  dvb_unregister_device(ca->dvbdev);
            kfree(ca->slot_info);
            kfree(ca);
      }
      pubca->private = NULL;
      return ret;
}
EXPORT_SYMBOL(dvb_ca_en50221_release);



/**
 * Release a DVB CA EN50221 interface device.
 *
 * @param ca_dev The dvb_device_t instance for the CA device.
 * @param ca The associated dvb_ca instance.
 */
void dvb_ca_en50221_release(struct dvb_ca_en50221 *pubca)
{
      struct dvb_ca_private *ca = pubca->private;
      int i;

      dprintk("%s\n", __FUNCTION__);

      /* shutdown the thread if there was one */
      kthread_stop(ca->thread);

      for (i = 0; i < ca->slot_count; i++) {
            dvb_ca_en50221_slot_shutdown(ca, i);
            vfree(ca->slot_info[i].rx_buffer.data);
      }
      kfree(ca->slot_info);
      dvb_unregister_device(ca->dvbdev);
      kfree(ca);
      pubca->private = NULL;
}

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