/*
 * Sony CDU-31A CDROM interface device driver.
 *
 * Corey Minyard (minyard@wf-rch.cirr.com)
 *
 * Colossians 3:17
 *
 * The Sony interface device driver handles Sony interface CDROM
 * drives and provides a complete block-level interface as well as an
 * ioctl() interface compatible with the Sun (as specified in
 * include/linux/cdrom.h).  With this interface, CDROMs can be
 * accessed and standard audio CDs can be played back normally.
 *
 * WARNING - 	All autoprobes have been removed from the driver.
 *		You MUST configure the CDU31A via a LILO config
 *		at boot time or in lilo.conf.  I have the
 *		following in my lilo.conf:
 *
 *                append="cdu31a=0x1f88,0,PAS"
 *
 *		The first number is the I/O base address of the
 *		card.  The second is the interrupt (0 means none).
 *		The third should be "PAS" if on a Pro-Audio
 *		spectrum, or nothing if on something else.
 *
 * This interface is (unfortunately) a polled interface.  This is
 * because most Sony interfaces are set up with DMA and interrupts
 * disables.  Some (like mine) do not even have the capability to
 * handle interrupts or DMA.  For this reason you will see a lot of
 * the following:
 *
 *   retry_count = jiffies+ SONY_JIFFIES_TIMEOUT;
 *   while ((retry_count > jiffies) && (! <some condition to wait for))
 *   {
 *      while (handle_sony_cd_attention())
 *         ;
 *
 *      sony_sleep();
 *   }
 *   if (the condition not met)
 *   {
 *      return an error;
 *   }
 *
 * This ugly hack waits for something to happen, sleeping a little
 * between every try.  it also handles attentions, which are
 * asynchronous events from the drive informing the driver that a disk
 * has been inserted, removed, etc.
 *
 * NEWS FLASH - The driver now supports interrupts but they are
 * turned off by default.  Use of interrupts is highly encouraged, it
 * cuts CPU usage down to a reasonable level.  I had DMA in for a while
 * but PC DMA is just too slow.  Better to just insb() it.
 *
 * One thing about these drives: They talk in MSF (Minute Second Frame) format.
 * There are 75 frames a second, 60 seconds a minute, and up to 75 minutes on a
 * disk.  The funny thing is that these are sent to the drive in BCD, but the
 * interface wants to see them in decimal.  A lot of conversion goes on.
 *
 * DRIVER SPECIAL FEATURES
 * -----------------------
 *
 * This section describes features beyond the normal audio and CD-ROM
 * functions of the drive.
 *
 * 2048 byte buffer mode
 *
 * If a disk is mounted with -o block=2048, data is copied straight
 * from the drive data port to the buffer.  Otherwise, the readahead
 * buffer must be involved to hold the other 1K of data when a 1K
 * block operation is done.  Note that with 2048 byte blocks you
 * cannot execute files from the CD.
 *
 * XA compatibility
 *
 * The driver should support XA disks for both the CDU31A and CDU33A.
 * It does this transparently, the using program doesn't need to set it.
 *
 * Multi-Session
 *
 * A multi-session disk looks just like a normal disk to the user.
 * Just mount one normally, and all the data should be there.
 * A special thanks to Koen for help with this!
 * 
 * Raw sector I/O
 *
 * Using the CDROMREADAUDIO it is possible to read raw audio and data
 * tracks.  Both operations return 2352 bytes per sector.  On the data
 * tracks, the first 12 bytes is not returned by the drive and the value
 * of that data is indeterminate.
 *
 *
 *  Copyright (C) 1993  Corey Minyard
 *
 *  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.
 *
 */

/*
 *
 * Setting up the Sony CDU31A/CDU33A drive interface card.  If
 * You have another card, you are on your own.
 * 
 *      +----------+-----------------+----------------------+
 *      |  JP1     |  34 Pin Conn    |                      |
 *      |  JP2     +-----------------+                      |
 *      |  JP3                                              |
 *      |  JP4                                              |
 *      |                                                   +--+
 *      |                                                   |  +-+
 *      |                                                   |  | |  External
 *      |                                                   |  | |  Connector
 *      |                                                   |  | |
 *      |                                                   |  +-+
 *      |                                                   +--+
 *      |                                                   |
 *      |                                          +--------+
 *      |                                          |
 *      +------------------------------------------+
 * 
 *    JP1 sets the Base Address, using the following settings:
 * 
 *      Address         Pin 1           Pin 2
 *      -------         -----           -----
 *      0x320           Short           Short
 *      0x330           Short           Open
 *      0x340           Open            Short
 *      0x360           Open            Open
 * 
 *    JP2 and JP3 configure the DMA channel; they must be set the same.
 * 
 *      DMA             Pin 1           Pin 2           Pin 3
 *      ---             -----           -----           -----
 *      1               On              Off             On
 *      2               Off             On              Off
 *      3               Off             Off             On
 * 
 *    JP4 Configures the IRQ:
 * 
 *      IRQ     Pin 1           Pin 2           Pin 3           Pin 4
 *      ---     -----           -----           -----           -----
 *      3       Off             Off             On              Off
 *      4       Off             Off*            Off             On
 *      5       On              Off             Off             Off
 *      6       Off             On              Off             Off
 * 
 *              * The documentation states to set this for interrupt
 *                4, but I think that is a mistake.
 */

#include <linux/errno.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/timer.h>
#include <linux/fs.h>
#include <linux/kernel.h>
#include <linux/hdreg.h>
#include <linux/genhd.h>
#include <linux/ioport.h>
#include <linux/string.h>
#include <linux/malloc.h>

#include <asm/system.h>
#include <asm/io.h>
#include <asm/segment.h>
#include <asm/dma.h>

#include <linux/cdrom.h>
#include <linux/cdu31a.h>

#define MAJOR_NR CDU31A_CDROM_MAJOR
#include "blk.h"

#define DEBUG 0

#define CDU31A_READAHEAD 64  /* 64 sector, 32kB, 16 reads read-ahead */
#define CDU31A_MAX_CONSECUTIVE_ATTENTIONS 10

/* Define the following if you have data corruption problems. */
#undef SONY_POLL_EACH_BYTE

/*
** Edit the following data to change interrupts, DMA channels, etc.
** Default is polled and no DMA.  DMA is not recommended for double-speed
** drives.
*/
static struct
{
   unsigned short base;         /* I/O Base Address */
   short          int_num;      /* Interrupt Number (-1 means scan for it,
                                   0 means don't use) */
} cdu31a_addresses[] =
{
#if 0	/* No autoconfig any more. See Note at beginning
	   of this file. */
   { 0x340,     0 },    /* Standard configuration Sony Interface */
   { 0x1f88,    0 },    /* Fusion CD-16 */
   { 0x230,     0 },    /* SoundBlaster 16 card */
   { 0x360,     0 },    /* Secondary standard Sony Interface */
   { 0x320,     0 },    /* Secondary standard Sony Interface */
   { 0x330,     0 },    /* Secondary standard Sony Interface */
   { 0x634,     0 },    /* Sound FX SC400 */
   { 0x654,     0 },    /* Sound FX SC400 */
#endif
   { 0 }
};

static int handle_sony_cd_attention(void);
static int read_subcode(void);
static void sony_get_toc(void);
static int scd_open(struct inode *inode, struct file *filp);
static void do_sony_cd_cmd(unsigned char cmd,
                           unsigned char *params,
                           unsigned int num_params,
                           unsigned char *result_buffer,
                           unsigned int *result_size);
static void size_to_buf(unsigned int size,
                        unsigned char *buf);

/* Parameters for the read-ahead. */
static unsigned int sony_next_block;      /* Next 512 byte block offset */
static unsigned int sony_blocks_left = 0; /* Number of 512 byte blocks left
                                             in the current read command. */


/* The base I/O address of the Sony Interface.  This is a variable (not a
   #define) so it can be easily changed via some future ioctl() */
static unsigned short sony_cd_base_io = 0;

/*
 * The following are I/O addresses of the various registers for the drive.  The
 * comment for the base address also applies here.
 */
static volatile unsigned short sony_cd_cmd_reg;
static volatile unsigned short sony_cd_param_reg;
static volatile unsigned short sony_cd_write_reg;
static volatile unsigned short sony_cd_control_reg;
static volatile unsigned short sony_cd_status_reg;
static volatile unsigned short sony_cd_result_reg;
static volatile unsigned short sony_cd_read_reg;
static volatile unsigned short sony_cd_fifost_reg;


static int sony_spun_up = 0;               /* Has the drive been spun up? */

static int sony_xa_mode = 0;               /* Is an XA disk in the drive
					      and the drive a CDU31A? */

static int sony_raw_data_mode = 1;         /* 1 if data tracks, 0 if audio.
                                              For raw data reads. */

static unsigned int sony_usage = 0;        /* How many processes have the
                                              drive open. */

static int sony_pas_init = 0;		   /* Initialize the Pro-Audio
					      Spectrum card? */

static struct s_sony_session_toc *sony_toc; /* Points to the
					       table of
					       contents. */

static int sony_toc_read = 0;		   /* Has the TOC been read for
					      the drive? */

static struct s_sony_subcode * volatile last_sony_subcode; /* Points to the last
                                                    subcode address read */

static volatile int sony_inuse = 0;  /* Is the drive in use?  Only one operation
					at a time allowed */

static struct wait_queue * sony_wait = NULL;	/* Things waiting for the drive */

static struct task_struct *has_cd_task = NULL;  /* The task that is currently
						   using the CDROM drive, or
						   NULL if none. */

static int is_double_speed = 0; /* Is the drive a CDU33A? */

/*
 * The audio status uses the values from read subchannel data as specified
 * in include/linux/cdrom.h.
 */
static volatile int sony_audio_status = CDROM_AUDIO_NO_STATUS;

/*
 * The following are a hack for pausing and resuming audio play.  The drive
 * does not work as I would expect it, if you stop it then start it again,
 * the drive seeks back to the beginning and starts over.  This holds the
 * position during a pause so a resume can restart it.  It uses the
 * audio status variable above to tell if it is paused.
 */
static unsigned volatile char cur_pos_msf[3] = { 0, 0, 0 };
static unsigned volatile char final_pos_msf[3] = { 0, 0, 0 };

/* What IRQ is the drive using?  0 if none. */
static int irq_used = 0;

/* The interrupt handler will wake this queue up when it gets an
   interrupts. */
static struct wait_queue *cdu31a_irq_wait = NULL;

static int curr_control_reg = 0; /* Current value of the control register */

/* A disk changed variable.  When a disk change is detected, it will
   all be set to TRUE.  As the upper layers ask for disk_changed status
   it will be cleared. */
static char disk_changed;

/* Variable for using the readahead buffer.  The readahead buffer
   is used for raw sector reads and for blocksizes that are smaller
   than 2048 bytes. */
static char *readahead_buffer = NULL; /* Used for 1024 byte blocksize. */
static int readahead_dataleft = 0;
static int readahead_bad = 0;


/*
 * This routine returns 1 if the disk has been changed since the last
 * check or 0 if it hasn't.
 */
static int
scd_disk_change(dev_t full_dev)
{
   int retval;

   retval = disk_changed;
   disk_changed = 0;

   return retval;
}

static inline void
enable_interrupts(void)
{
   curr_control_reg |= (  SONY_ATTN_INT_EN_BIT
                        | SONY_RES_RDY_INT_EN_BIT
                        | SONY_DATA_RDY_INT_EN_BIT);
   outb(curr_control_reg, sony_cd_control_reg);
}

static inline void
disable_interrupts(void)
{
   curr_control_reg &= ~(  SONY_ATTN_INT_EN_BIT
                         | SONY_RES_RDY_INT_EN_BIT
                         | SONY_DATA_RDY_INT_EN_BIT);
   outb(curr_control_reg, sony_cd_control_reg);
}

static void
cdu31a_interrupt(int irq, struct pt_regs *regs)
{
   disable_interrupts();
   if (cdu31a_irq_wait != NULL)
   {
      wake_up(&cdu31a_irq_wait);
   }
   else
   {
      printk("CDU31A: Got an interrupt but nothing was waiting\n");
   }
}

/*
 * Wait a little while (used for polling the drive).  If in initialization,
 * setting a timeout doesn't work, so just loop for a while.
 */
static inline void
sony_sleep(void)
{
   if (irq_used <= 0)
   {
      current->state = TASK_INTERRUPTIBLE;
      current->timeout = jiffies;
      schedule();
   }
   else /* Interrupt driven */
   {
      cli();
      enable_interrupts();
      interruptible_sleep_on(&cdu31a_irq_wait);
      sti();
   }
}


/*
 * The following are convenience routine to read various status and set
 * various conditions in the drive.
 */
static inline int
is_attention(void)
{
   return((inb(sony_cd_status_reg) & SONY_ATTN_BIT) != 0);
}

static inline int
is_busy(void)
{
   return((inb(sony_cd_status_reg) & SONY_BUSY_BIT) != 0);
}

static inline int
is_data_ready(void)
{
   return((inb(sony_cd_status_reg) & SONY_DATA_RDY_BIT) != 0);
}

static inline int
is_data_requested(void)
{
   return((inb(sony_cd_status_reg) & SONY_DATA_REQUEST_BIT) != 0);
}

static inline int
is_result_ready(void)
{
   return((inb(sony_cd_status_reg) & SONY_RES_RDY_BIT) != 0);
}

static inline int
is_param_write_rdy(void)
{
   return((inb(sony_cd_fifost_reg) & SONY_PARAM_WRITE_RDY_BIT) != 0);
}

static inline int
is_result_reg_not_empty(void)
{
   return((inb(sony_cd_fifost_reg) & SONY_RES_REG_NOT_EMP_BIT) != 0);
}

static inline void
reset_drive(void)
{
   curr_control_reg = 0;
   outb(SONY_DRIVE_RESET_BIT, sony_cd_control_reg);
}

static inline void
clear_attention(void)
{
   outb(curr_control_reg | SONY_ATTN_CLR_BIT, sony_cd_control_reg);
}

static inline void
clear_result_ready(void)
{
   outb(curr_control_reg | SONY_RES_RDY_CLR_BIT, sony_cd_control_reg);
}

static inline void
clear_data_ready(void)
{
   outb(curr_control_reg | SONY_DATA_RDY_CLR_BIT, sony_cd_control_reg);
}

static inline void
clear_param_reg(void)
{
   outb(curr_control_reg | SONY_PARAM_CLR_BIT, sony_cd_control_reg);
}

static inline unsigned char
read_status_register(void)
{
   return(inb(sony_cd_status_reg));
}

static inline unsigned char
read_result_register(void)
{
   return(inb(sony_cd_result_reg));
}

static inline unsigned char
read_data_register(void)
{
   return(inb(sony_cd_read_reg));
}

static inline void
write_param(unsigned char param)
{
   outb(param, sony_cd_param_reg);
}

static inline void
write_cmd(unsigned char cmd)
{
   outb(curr_control_reg | SONY_RES_RDY_INT_EN_BIT, sony_cd_control_reg);
   outb(cmd, sony_cd_cmd_reg);
}

/*
 * Set the drive parameters so the drive will auto-spin-up when a
 * disk is inserted.
 */
static void
set_drive_params(void)
{
   unsigned char res_reg[12];
   unsigned int res_size;
   unsigned char params[3];


   params[0] = SONY_SD_MECH_CONTROL;
   params[1] = 0x03; /* Set auto spin up and auto eject */
   if (is_double_speed)
   {
      params[1] |= 0x04; /* Set the drive to double speed if possible */
   }
   do_sony_cd_cmd(SONY_SET_DRIVE_PARAM_CMD,
                  params,
                  2,
                  res_reg,
                  &res_size);
   if ((res_size < 2) || ((res_reg[0] & 0xf0) == 0x20))
   {
      printk("  Unable to set mechanical parameters: 0x%2.2x\n", res_reg[1]);
   }
}

/*
 * This code will reset the drive and attempt to restore sane parameters.
 */
static void
restart_on_error(void)
{
   unsigned char res_reg[12];
   unsigned int res_size;
   unsigned int retry_count;


   printk("cdu31a: Resetting drive on error\n");
   reset_drive();
   retry_count = jiffies + SONY_RESET_TIMEOUT;
   while ((retry_count > jiffies) && (!is_attention()))
   {
      sony_sleep();
   }
   set_drive_params();
   do_sony_cd_cmd(SONY_SPIN_UP_CMD, NULL, 0, res_reg, &res_size);
   if ((res_size < 2) || ((res_reg[0] & 0xf0) == 0x20))
   {
      printk("cdu31a: Unable to spin up drive: 0x%2.2x\n", res_reg[1]);
   }

   current->state = TASK_INTERRUPTIBLE;
   current->timeout = jiffies + 200;
   schedule();

   do_sony_cd_cmd(SONY_READ_TOC_CMD, NULL, 0, res_reg, &res_size);
   if ((res_size < 2) || ((res_reg[0] & 0xf0) == 0x20))
   {
      printk("cdu31a: Unable to read TOC: 0x%2.2x\n", res_reg[1]);
   }
}

/*
 * This routine writes data to the parameter register.  Since this should
 * happen fairly fast, it is polled with no OS waits between.
 */
static int
write_params(unsigned char *params,
             int num_params)
{
   unsigned int retry_count;


   retry_count = SONY_READY_RETRIES;
   while ((retry_count > 0) && (!is_param_write_rdy()))
   {
      retry_count--;
   }
   if (!is_param_write_rdy())
   {
      return -EIO;
   }

   while (num_params > 0)
   {
      write_param(*params);
      params++;
      num_params--;
   }

   return 0;
}


/*
 * The following reads data from the command result register.  It is a
 * fairly complex routine, all status info flows back through this
 * interface.  The algorithm is stolen directly from the flowcharts in
 * the drive manual.
 */
static void
get_result(unsigned char *result_buffer,
           unsigned int *result_size)
{
   unsigned char a, b;
   int i;
   unsigned int retry_count;


   while (handle_sony_cd_attention())
      ;
   /* Wait for the result data to be ready */
   retry_count = jiffies + SONY_JIFFIES_TIMEOUT;
   while ((retry_count > jiffies) && (is_busy() || (!(is_result_ready()))))
   {
      sony_sleep();

      while (handle_sony_cd_attention())
         ;
   }
   if (is_busy() || (!(is_result_ready())))
   {
#if DEBUG
      printk("CDU31A timeout out %d\n", __LINE__);
#endif
      result_buffer[0] = 0x20;
      result_buffer[1] = SONY_TIMEOUT_OP_ERR;
      *result_size = 2;
      return;
   }

   /*
    * Get the first two bytes.  This determines what else needs
    * to be done.
    */
   clear_result_ready();
   a = read_result_register();
   *result_buffer = a;
   result_buffer++;

   /* Check for block error status result. */
   if ((a & 0xf0) == 0x50)
   {
      *result_size = 1;
      return;
   }

   b = read_result_register();
   *result_buffer = b;
   result_buffer++;
   *result_size = 2;

   /*
    * 0x20 means an error occurred.  Byte 2 will have the error code.
    * Otherwise, the command succeeded, byte 2 will have the count of
    * how many more status bytes are coming.
    *
    * The result register can be read 10 bytes at a time, a wait for
    * result ready to be asserted must be done between every 10 bytes.
    */
   if ((a & 0xf0) != 0x20)
   {
      if (b > 8)
      {
         for (i=0; i<8; i++)
         {
            *result_buffer = read_result_register();
            result_buffer++;
            (*result_size)++;
         }
         b = b - 8;

         while (b > 10)
         {
            retry_count = SONY_READY_RETRIES;
            while ((retry_count > 0) && (!is_result_ready()))
            {
               retry_count--;
            }
            if (!is_result_ready())
            {
#if DEBUG
               printk("CDU31A timeout out %d\n", __LINE__);
#endif
               result_buffer[0] = 0x20;
               result_buffer[1] = SONY_TIMEOUT_OP_ERR;
               *result_size = 2;
               return;
            }

            clear_result_ready();
                                
            for (i=0; i<10; i++)
            {
               *result_buffer = read_result_register();
               result_buffer++;
               (*result_size)++;
            }
            b = b - 10;
         }

         if (b > 0)
         {
            retry_count = SONY_READY_RETRIES;
            while ((retry_count > 0) && (!is_result_ready()))
            {
               retry_count--;
            }
            if (!is_result_ready())
            {
#if DEBUG
               printk("CDU31A timeout out %d\n", __LINE__);
#endif
               result_buffer[0] = 0x20;
               result_buffer[1] = SONY_TIMEOUT_OP_ERR;
               *result_size = 2;
               return;
            }
         }
      }

      while (b > 0)
      {
         *result_buffer = read_result_register();
         result_buffer++;
         (*result_size)++;
         b--;
      }
   }
}

/*
 * Do a command that does not involve data transfer.  This routine must
 * be re-entrant from the same task to support being called from the
 * data operation code when an error occurs.
 */
static void
do_sony_cd_cmd(unsigned char cmd,
               unsigned char *params,
               unsigned int num_params,
               unsigned char *result_buffer,
               unsigned int *result_size)
{
   unsigned int retry_count;
   int num_retries;
   int recursive_call;


   cli();
   if (current != has_cd_task) /* Allow recursive calls to this routine */
   {
      while (sony_inuse)
      {
         interruptible_sleep_on(&sony_wait);
         if (current->signal & ~current->blocked)
         {
            result_buffer[0] = 0x20;
            result_buffer[1] = SONY_SIGNAL_OP_ERR;
            *result_size = 2;
            return;
         }
      }
      sony_inuse = 1;
      has_cd_task = current;
      recursive_call = 0;
   }
   else
   {
      recursive_call = 1;
   }
   sti();

   num_retries = 0;
retry_cd_operation:

   while (handle_sony_cd_attention())
      ;
   
   retry_count = jiffies + SONY_JIFFIES_TIMEOUT;
   while ((retry_count > jiffies) && (is_busy()))
   {
      sony_sleep();
      
      while (handle_sony_cd_attention())
         ;
   }
   if (is_busy())
   {
#if DEBUG
      printk("CDU31A timeout out %d\n", __LINE__);
#endif
      result_buffer[0] = 0x20;
      result_buffer[1] = SONY_TIMEOUT_OP_ERR;
      *result_size = 2;
   }
   else
   {
      clear_result_ready();
      clear_param_reg();

      write_params(params, num_params);
      write_cmd(cmd);

      get_result(result_buffer, result_size);
   }

   if (   ((result_buffer[0] & 0xf0) == 0x20)
       && (num_retries < MAX_CDU31A_RETRIES))
   {
      num_retries++;
      current->state = TASK_INTERRUPTIBLE;
      current->timeout = jiffies + 10; /* Wait .1 seconds on retries */
      schedule();
      goto retry_cd_operation;
   }

   if (!recursive_call)
   {
      has_cd_task = NULL;
      sony_inuse = 0;
      wake_up_interruptible(&sony_wait);
   }
}


/*
 * Handle an attention from the drive.  This will return 1 if it found one
 * or 0 if not (if one is found, the caller might want to call again).
 *
 * This routine counts the number of consecutive times it is called
 * (since this is always called from a while loop until it returns
 * a 0), and returns a 0 if it happens too many times.  This will help
 * prevent a lockup.
 */
static int
handle_sony_cd_attention(void)
{
   unsigned char atten_code;
   static int num_consecutive_attentions = 0;


   if (is_attention())
   {
      if (num_consecutive_attentions > CDU31A_MAX_CONSECUTIVE_ATTENTIONS)
      {
         printk("cdu31a: Too many consecutive attentions: %d\n",
                num_consecutive_attentions);
         num_consecutive_attentions = 0;
         return(0);
      }

      clear_attention();
      atten_code = read_result_register();

      switch (atten_code)
      {
       /* Someone changed the CD.  Mark it as changed */
      case SONY_MECH_LOADED_ATTN:
         disk_changed = 1;
	 sony_toc_read = 0;
         sony_audio_status = CDROM_AUDIO_NO_STATUS;
         sony_blocks_left = 0;
         break;

      case SONY_SPIN_DOWN_COMPLETE_ATTN:
         /* Mark the disk as spun down. */
         sony_spun_up = 0;
         break;

      case SONY_AUDIO_PLAY_DONE_ATTN:
         sony_audio_status = CDROM_AUDIO_COMPLETED;
         read_subcode();
         break;

      case SONY_EJECT_PUSHED_ATTN:
         sony_audio_status = CDROM_AUDIO_INVALID;
         break;

      case SONY_LEAD_IN_ERR_ATTN:
      case SONY_LEAD_OUT_ERR_ATTN:
      case SONY_DATA_TRACK_ERR_ATTN:
      case SONY_AUDIO_PLAYBACK_ERR_ATTN:
         sony_audio_status = CDROM_AUDIO_ERROR;
         break;
      }

      num_consecutive_attentions++;
      return(1);
   }

   num_consecutive_attentions = 0;
   return(0);
}


/* Convert from an integer 0-99 to BCD */
static inline unsigned int
int_to_bcd(unsigned int val)
{
   int retval;


   retval = (val / 10) << 4;
   retval = retval | val % 10;
   return(retval);
}


/* Convert from BCD to an integer from 0-99 */
static unsigned int
bcd_to_int(unsigned int bcd)
{
   return((((bcd >> 4) & 0x0f) * 10) + (bcd & 0x0f));
}


/*
 * Convert a logical sector value (like the OS would want to use for
 * a block device) to an MSF format.
 */
static void
log_to_msf(unsigned int log, unsigned char *msf)
{
   log = log + LOG_START_OFFSET;
   msf[0] = int_to_bcd(log / 4500);
   log = log % 4500;
   msf[1] = int_to_bcd(log / 75);
   msf[2] = int_to_bcd(log % 75);
}


/*
 * Convert an MSF format to a logical sector.
 */
static unsigned int
msf_to_log(unsigned char *msf)
{
   unsigned int log;


   log = bcd_to_int(msf[2]);
   log += bcd_to_int(msf[1]) * 75;
   log += bcd_to_int(msf[0]) * 4500;
   log = log - LOG_START_OFFSET;

   return log;
}


/*
 * Take in integer size value and put it into a buffer like
 * the drive would want to see a number-of-sector value.
 */
static void
size_to_buf(unsigned int size,
            unsigned char *buf)
{
   buf[0] = size / 65536;
   size = size % 65536;
   buf[1] = size / 256;
   buf[2] = size % 256;
}

/* Starts a read operation. Returns 0 on success and 1 on failure. 
   The read operation used here allows multiple sequential sectors 
   to be read and status returned for each sector.  The driver will
   read the out one at a time as the requests come and abort the
   operation if the requested sector is not the next one from the
   drive. */
static int
start_request(unsigned int sector,
              unsigned int nsect,
              int          read_nsect_only)
{
   unsigned char params[6];
   unsigned int read_size;
   unsigned int retry_count;


   log_to_msf(sector, params);
   /* If requested, read exactly what was asked. */
   if (read_nsect_only)
   {
      read_size = nsect;
   }
   /*
    * If the full read-ahead would go beyond the end of the media, trim
    * it back to read just till the end of the media.
    */
   else if ((sector + nsect) >= sony_toc->lead_out_start_lba)
   {
      read_size = sony_toc->lead_out_start_lba - sector;
   }
   /* Read the full readahead amount. */
   else
   {
      read_size = CDU31A_READAHEAD;
   }
   size_to_buf(read_size, &params[3]);

   /*
    * Clear any outstanding attentions and wait for the drive to
    * complete any pending operations.
    */
   while (handle_sony_cd_attention())
      ;

   retry_count = jiffies + SONY_JIFFIES_TIMEOUT;
   while ((retry_count > jiffies) && (is_busy()))
   {
      sony_sleep();
      
      while (handle_sony_cd_attention())
         ;
   }

   if (is_busy())
   {
      printk("CDU31A: Timeout while waiting to issue command\n");
      return(1);
   }
   else
   {
      /* Issue the command */
      clear_result_ready();
      clear_param_reg();

      write_params(params, 6);
      write_cmd(SONY_READ_BLKERR_STAT_CMD);

      sony_blocks_left = read_size * 4;
      sony_next_block = sector * 4;
      readahead_dataleft = 0;
      readahead_bad = 0;
      return(0);
   }
}

/* Abort a pending read operation.  Clear all the drive status and
   readahead variables. */
static void
abort_read(void)
{
   unsigned char result_reg[2];
   int           result_size;
   volatile int  val;


   do_sony_cd_cmd(SONY_ABORT_CMD, NULL, 0, result_reg, &result_size);
   if ((result_reg[0] & 0xf0) == 0x20)
   {
      printk("CDU31A: Error aborting read, error = 0x%2.2x\n",
             result_reg[1]);
   }

   while (is_result_reg_not_empty())
   {
      val = read_result_register();
   }
   clear_data_ready();
   clear_result_ready();
   /* Clear out the data */
   while (is_data_requested())
   {
      val = read_data_register();
   }

   sony_blocks_left = 0;
   readahead_dataleft = 0;
   readahead_bad = 0;
}

/* Actually get data and status from the drive. */
static void
input_data(char         *buffer,
           unsigned int bytesleft,
           unsigned int nblocks,
           unsigned int offset,
           unsigned int skip)
{
   int i;
   volatile unsigned char val;


   /* If an XA disk on a CDU31A, skip the first 12 bytes of data from
      the disk.  The real data is after that. */
   if (sony_xa_mode)
   {
      for(i=0; i<CD_XA_HEAD; i++)
      {
         val = read_data_register();
      }
   }

   clear_data_ready();

   if (bytesleft == 2048) /* 2048 byte direct buffer transfer */
   {
      insb(sony_cd_read_reg, buffer, 2048);
      readahead_dataleft = 0;
   }
   else
   {
      /* If the input read did not align with the beginning of the block,
	 skip the necessary bytes. */
      if (skip != 0)
      {
         insb(sony_cd_read_reg, readahead_buffer, skip);
      }

      /* Get the data into the buffer. */
      insb(sony_cd_read_reg, &buffer[offset], bytesleft);

      /* Get the rest of the data into the readahead buffer at the
	 proper location. */
      readahead_dataleft = (2048 - skip) - bytesleft;
      insb(sony_cd_read_reg,
           readahead_buffer + bytesleft,
           readahead_dataleft);
   }
   sony_blocks_left -= nblocks;
   sony_next_block += nblocks; 

   /* If an XA disk, we have to clear out the rest of the unused
      error correction data. */
   if (sony_xa_mode)
   {
      for(i=0; i<CD_XA_TAIL; i++)
      {
         val = read_data_register();
      }
   }
}

/* read data from the drive.  Note the nsect must be <= 4. */
static void
read_data_block(char          *buffer,
                unsigned int  block,
                unsigned int  nblocks,
                unsigned char res_reg[],
                int           *res_size)
{
   unsigned int retry_count;
   unsigned int bytesleft;
   unsigned int offset;
   unsigned int skip;


   res_reg[0] = 0;
   res_reg[1] = 0;
   *res_size = 0;
   bytesleft = nblocks * 512;
   offset = 0;

   /* If the data in the read-ahead does not match the block offset,
      then fix things up. */
   if (((block % 4) * 512) != ((2048 - readahead_dataleft) % 2048))
   {
      sony_next_block += block % 4;
      sony_blocks_left -= block % 4;
      skip = (block % 4) * 512;
   }
   else
   {
      skip = 0;
   }

   /* We have readahead data in the buffer, get that first before we
      decide if a read is necessary. */
   if (readahead_dataleft != 0)
   {
      if (bytesleft > readahead_dataleft)
      {
	 /* The readahead will not fill the requested buffer, but
	    get the data out of the readahead into the buffer. */
         memcpy(buffer,
                readahead_buffer + (2048 - readahead_dataleft),
                readahead_dataleft);
         readahead_dataleft = 0;
         bytesleft -= readahead_dataleft;
         offset += readahead_dataleft;
      }
      else
      {
	 /* The readahead will fill the whole buffer, get the data
	    and return. */
         memcpy(buffer,
                readahead_buffer + (2048 - readahead_dataleft),
                bytesleft);
         readahead_dataleft -= bytesleft;
         bytesleft = 0;
         sony_blocks_left -= nblocks;
         sony_next_block += nblocks;

	 /* If the data in the readahead is bad, return an error so the
	    driver will abort the buffer. */
         if (readahead_bad)
         {
            res_reg[0] = 0x20;
            res_reg[1] = SONY_BAD_DATA_ERR;
            *res_size = 2;
         }

         if (readahead_dataleft == 0)
         {
            readahead_bad = 0;
         }

         /* Final transfer is done for read command, get final result. */
         if (sony_blocks_left == 0)
         {
            get_result(res_reg, res_size);
         }
         return;
      }
   }

   /* Wait for the drive to tell us we have something */
   retry_count = jiffies + SONY_JIFFIES_TIMEOUT;
   while ((retry_count > jiffies) && !(is_data_ready()))
   {
      while (handle_sony_cd_attention())
         ;

      sony_sleep();
   }
   if (!(is_data_ready()))
   {
      if (is_result_ready())
      {
         get_result(res_reg, res_size);
         if ((res_reg[0] & 0xf0) != 0x20)
         {
            printk("CDU31A: Got result that should have been error: %d\n",
                   res_reg[0]);
            res_reg[0] = 0x20;
            res_reg[1] = SONY_BAD_DATA_ERR;
            *res_size = 2;
         }
         abort_read();
      }
      else
      {
#if DEBUG
         printk("CDU31A timeout out %d\n", __LINE__);
#endif
         res_reg[0] = 0x20;
         res_reg[1] = SONY_TIMEOUT_OP_ERR;
         *res_size = 2;
         abort_read();
      }
   }
   else
   {
      input_data(buffer, bytesleft, nblocks, offset, skip);

      /* Wait for the status from the drive. */
      retry_count = jiffies + SONY_JIFFIES_TIMEOUT;
      while ((retry_count > jiffies) && !(is_result_ready()))
      {
         while (handle_sony_cd_attention())
            ;

         sony_sleep();
      }

      if (!is_result_ready())
      {
#if DEBUG
         printk("CDU31A timeout out %d\n", __LINE__);
#endif
         res_reg[0] = 0x20;
         res_reg[1] = SONY_TIMEOUT_OP_ERR;
         *res_size = 2;
         abort_read();
      }
      else
      {
         get_result(res_reg, res_size);

	 /* If we got a buffer status, handle that. */
         if ((res_reg[0] & 0xf0) == 0x50)
         {

            if (   (res_reg[0] == SONY_NO_CIRC_ERR_BLK_STAT)
                || (res_reg[0] == SONY_NO_LECC_ERR_BLK_STAT)
                || (res_reg[0] == SONY_RECOV_LECC_ERR_BLK_STAT))
            {
	       /* The data was successful, but if data was read from
		  the readahead  and it was bad, set the whole
		  buffer as bad. */
               if (readahead_bad)
               {
                  readahead_bad = 0;
                  res_reg[0] = 0x20;
                  res_reg[1] = SONY_BAD_DATA_ERR;
                  *res_size = 2;
               }
            }
            else
            {
               printk("CDU31A: Data block error: 0x%x\n", res_reg[0]);
               res_reg[0] = 0x20;
               res_reg[1] = SONY_BAD_DATA_ERR;
               *res_size = 2;

               /* Data is in the readahead buffer but an error was returned.
                  Make sure future requests don't use the data. */
               if (bytesleft != 2048)
               {
                  readahead_bad = 1;
               }
            }

            /* Final transfer is done for read command, get final result. */
            if (sony_blocks_left == 0)
            {
               get_result(res_reg, res_size);
            }
         }
         else if ((res_reg[0] & 0xf0) != 0x20)
         {
            /* The drive gave me bad status, I don't know what to do.
               Reset the driver and return an error. */
            printk("CDU31A: Invalid block status: 0x%x\n", res_reg[0]);
            restart_on_error();
            res_reg[0] = 0x20;
            res_reg[1] = SONY_BAD_DATA_ERR;
            *res_size = 2;
         }
      }
   }
}

/*
 * The OS calls this to perform a read or write operation to the drive.
 * Write obviously fail.  Reads to a read ahead of sony_buffer_size
 * bytes to help speed operations.  This especially helps since the OS
 * uses 1024 byte blocks and the drive uses 2048 byte blocks.  Since most
 * data access on a CD is done sequentially, this saves a lot of operations.
 */
static void
do_cdu31a_request(void)
{
   int block;
   int nblock;
   unsigned char res_reg[12];
   unsigned int res_size;
   int num_retries;


   /* 
    * Make sure no one else is using the driver; wait for them
    * to finish if it is so.
    */
   cli();
   while (sony_inuse)
   {
      interruptible_sleep_on(&sony_wait);
      if (current->signal & ~current->blocked)
      {
         return;
      }
   }
   sony_inuse = 1;
   has_cd_task = current;
   sti();

   /* Get drive status before doing anything. */
   while (handle_sony_cd_attention())
      ;

   while (1)
   {
cdu31a_request_startover:
      /*
       * The beginning here is stolen from the hard disk driver.  I hope
       * its right.
       */
      if (!(CURRENT) || CURRENT->dev < 0)
      {
         goto end_do_cdu31a_request;
      }

      if (!sony_spun_up)
      {
         struct inode in;

         /* This is a kludge to get a valid dev in an inode that
            scd_open can take.  That's the only thing scd_open()
            uses the inode for. */
         in.i_rdev = CURRENT->dev;
         scd_open(&in,NULL);
      }

      /* I don't use INIT_REQUEST because it calls return, which would
         return without unlocking the device.  It shouldn't matter,
         but just to be safe... */
      if (MAJOR(CURRENT->dev) != MAJOR_NR)
      {
	 panic(DEVICE_NAME ": request list destroyed");
      }
      if (CURRENT->bh)
      {
	 if (!CURRENT->bh->b_lock)
         {
	    panic(DEVICE_NAME ": block not locked");
         }
      }

      block = CURRENT->sector;
      nblock = CURRENT->nr_sectors;

      if (!sony_toc_read)
      {
	 printk("CDU31A: TOC not read\n");
	 end_request(0);
	 goto cdu31a_request_startover;
      }

      /* Check for base read of multi-session disk.  This will still work
         for single session disks, so just do it.  Blocks less than 80
         are for the volume info, so offset them by the start track (which
         should be zero for a single-session disk). */
      if (block < 80)
      {
	 /* Offset the request into the session. */
	 block += (sony_toc->start_track_lba * 4);
      }

      switch(CURRENT->cmd)
      {
      case READ:
         /*
          * If the block address is invalid or the request goes beyond the end of
          * the media, return an error.
          */
#if 0
	 if ((block / 4) < sony_toc->start_track_lba)
	 {
            printk("CDU31A: Request before beginning of media\n");
            end_request(0);
            goto cdu31a_request_startover;
	 }
#endif
         if ((block / 4) >= sony_toc->lead_out_start_lba)
         {
            printk("CDU31A: Request past end of media\n");
            end_request(0);
            goto cdu31a_request_startover;
         }
         if (((block + nblock) / 4) >= sony_toc->lead_out_start_lba)
         {
            printk("CDU31A: Request past end of media\n");
            end_request(0);
            goto cdu31a_request_startover;
         }

         num_retries = 0;

try_read_again:
         while (handle_sony_cd_attention())
            ;

         if (!sony_toc_read)
         {
	    printk("CDU31A: TOC not read\n");
	    end_request(0);
	    goto cdu31a_request_startover;
         }

	 /* If no data is left to be read from the drive, start the
	    next request. */
         if (sony_blocks_left == 0)
         {
            if (start_request(block / 4, CDU31A_READAHEAD / 4, 0))
            {
               end_request(0);
               goto cdu31a_request_startover;
            }
         }
	 /* If the requested block is not the next one waiting in
	    the driver, abort the current operation and start a
	    new one. */
         else if (block != sony_next_block)
         {
#if DEBUG
            printk("CDU31A Warning: Read for block %d, expected %d\n",
                   block,
                   sony_next_block);
#endif
            abort_read();
            if (!sony_toc_read)
            {
	       printk("CDU31A: TOC not read\n");
	       end_request(0);
               goto cdu31a_request_startover;
            }
            if (start_request(block / 4, CDU31A_READAHEAD / 4, 0))
            {
               end_request(0);
               goto cdu31a_request_startover;
            }
         }

         read_data_block(CURRENT->buffer, block, nblock, res_reg, &res_size);
         if (res_reg[0] == 0x20)
         {
            if (num_retries > MAX_CDU31A_RETRIES)
            {
               end_request(0);
               goto cdu31a_request_startover;
            }

            num_retries++;
            if (res_reg[1] == SONY_NOT_SPIN_ERR)
            {
               do_sony_cd_cmd(SONY_SPIN_UP_CMD, NULL, 0, res_reg, &res_size);
            }
            else
            {
               printk("CDU31A: Read error: 0x%2.2x\n", res_reg[1]);
            }
            goto try_read_again;
         }
         else
         {
            end_request(1);
         }
         break;
            
      case WRITE:
         end_request(0);
         break;
            
      default:
         panic("CDU31A: Unknown cmd");
      }
   }

end_do_cdu31a_request:
#if 1
   /* After finished, cancel any pending operations. */
   abort_read();
#endif

   has_cd_task = NULL;
   sony_inuse = 0;
   wake_up_interruptible(&sony_wait);
}

/* Copy overlapping buffers. */
static void
mcovlp(char *dst,
       char *src,
       int  size)
{
   src += (size - 1);
   dst += (size - 1);
   while (size > 0)
   {
      *dst = *src;
      size--;
      dst--;
      src--;
   }
}


/*
 * Read the table of contents from the drive and set up TOC if
 * successful.
 */
static void
sony_get_toc(void)
{
   unsigned char res_reg[2];
   unsigned int res_size;
   unsigned char parms[1];
   int session;


#if DEBUG
   printk("Entering sony_get_toc\n");
#endif

   if (!sony_toc_read)
   {
      /* The idea here is we keep asking for sessions until the command
	 fails.  Then we know what the last valid session on the disk is.
	 No need to check session 0, since session 0 is the same as session
         1; the command returns different information if you give it 0. 
         Don't check session 1 because that is the first session, it must
         be there. */
      session = 2;
      while (1)
      {
#if DEBUG
         printk("Trying session %d\n", session);
#endif
	 parms[0] = session;
	 do_sony_cd_cmd(SONY_READ_TOC_SPEC_CMD,
			parms,
			1, 
			res_reg,
			&res_size);

#if DEBUG
         printk("%2.2x %2.2x\n", res_reg[0], res_reg[1]);
#endif

	 if ((res_size < 2) || ((res_reg[0] & 0xf0) == 0x20))
	 {
	    /* An error reading the TOC, this must be past the last session. */
	    break;
         }

         session++;

         /* Let's not get carried away... */
         if (session > 20)
         {
            return;
         }
      }

      session--;

#if DEBUG
      printk("Reading session %d\n", session);
#endif

      parms[0] = session;
      do_sony_cd_cmd(SONY_REQ_TOC_DATA_SPEC_CMD,
		     parms,
		     1, 
		     (unsigned char *) sony_toc, 
		     &res_size);
      if ((res_size < 2) || ((sony_toc->exec_status[0] & 0xf0) == 0x20))
      {
	 /* An error reading the TOC.  Return without sony_toc_read
	    set. */
	 return;
      }
      
      sony_toc_read = 1;

      /* For points that do not exist, move the data over them
	 to the right location. */
      if (sony_toc->pointb0 != 0xb0)
      {
	 mcovlp(((char *) sony_toc) + 27,
		((char *) sony_toc) + 18,
		res_size - 18);
	 res_size += 9;
      }
      if (sony_toc->pointb1 != 0xb1)
      {
	 mcovlp(((char *) sony_toc) + 36,
		((char *) sony_toc) + 27,
		res_size - 27);
	 res_size += 9;
      }
      if (sony_toc->pointb2 != 0xb2)
      {
	 mcovlp(((char *) sony_toc) + 45,
		((char *) sony_toc) + 36,
		res_size - 36);
	 res_size += 9;
      }
      if (sony_toc->pointb3 != 0xb3)
      {
	 mcovlp(((char *) sony_toc) + 54,
		((char *) sony_toc) + 45,
		res_size - 45);
	 res_size += 9;
      }
      if (sony_toc->pointb4 != 0xb4)
      {
	 mcovlp(((char *) sony_toc) + 63,
		((char *) sony_toc) + 54,
		res_size - 54);
	 res_size += 9;
      }
      if (sony_toc->pointc0 != 0xc0)
      {
	 mcovlp(((char *) sony_toc) + 72,
		((char *) sony_toc) + 63,
		res_size - 63);
	 res_size += 9;
      }

      sony_toc->start_track_lba = msf_to_log(sony_toc->tracks[0].track_start_msf);
      sony_toc->lead_out_start_lba = msf_to_log(sony_toc->lead_out_start_msf);

#if DEBUG
   printk("Disk session %d, start track: %d, stop track: %d\n",
	  session,
	  sony_toc->start_track_lba,
	  sony_toc->lead_out_start_lba);
#endif
   }
#if DEBUG
   printk("Leaving sony_get_toc\n");
#endif
}


/*
 * Search for a specific track in the table of contents.
 */
static int
find_track(int track)
{
   int i;
   int num_tracks;


   num_tracks = sony_toc->last_track_num - sony_toc->first_track_num + 1;
   for (i = 0; i < num_tracks; i++)
   {
      if (sony_toc->tracks[i].track == track)
      {
         return i;
      }
   }

   return -1;
}


/*
 * Read the subcode and put it int last_sony_subcode for future use.
 */
static int
read_subcode(void)
{
   unsigned int res_size;


   do_sony_cd_cmd(SONY_REQ_SUBCODE_ADDRESS_CMD,
                  NULL,
                  0, 
                  (unsigned char *) last_sony_subcode, 
                  &res_size);
   if ((res_size < 2) || ((last_sony_subcode->exec_status[0] & 0xf0) == 0x20))
   {
      printk("Sony CDROM error 0x%2.2x (read_subcode)\n",
             last_sony_subcode->exec_status[1]);
      return -EIO;
   }

   return 0;
}


/*
 * Get the subchannel info like the CDROMSUBCHNL command wants to see it.  If
 * the drive is playing, the subchannel needs to be read (since it would be
 * changing).  If the drive is paused or completed, the subcode information has
 * already been stored, just use that.  The ioctl call wants things in decimal
 * (not BCD), so all the conversions are done.
 */
static int
sony_get_subchnl_info(long arg)
{
   struct cdrom_subchnl schi;


   /* Get attention stuff */
   while (handle_sony_cd_attention())
      ;

   sony_get_toc();
   if (!sony_toc_read)
   {
      return -EIO;
   }

   verify_area(VERIFY_READ, (char *) arg, sizeof(schi));
   verify_area(VERIFY_WRITE, (char *) arg, sizeof(schi));

   memcpy_fromfs(&schi, (char *) arg, sizeof(schi));
   
   switch (sony_audio_status)
   {
   case CDROM_AUDIO_PLAY:
      if (read_subcode() < 0)
      {
         return -EIO;
      }
      break;

   case CDROM_AUDIO_PAUSED:
   case CDROM_AUDIO_COMPLETED:
      break;

   case CDROM_AUDIO_NO_STATUS:
      schi.cdsc_audiostatus = sony_audio_status;
      memcpy_tofs((char *) arg, &schi, sizeof(schi));
      return 0;
      break;

   case CDROM_AUDIO_INVALID:
   case CDROM_AUDIO_ERROR:
   default:
      return -EIO;
   }

   schi.cdsc_audiostatus = sony_audio_status;
   schi.cdsc_adr = last_sony_subcode->address;
   schi.cdsc_ctrl = last_sony_subcode->control;
   schi.cdsc_trk = bcd_to_int(last_sony_subcode->track_num);
   schi.cdsc_ind = bcd_to_int(last_sony_subcode->index_num);
   if (schi.cdsc_format == CDROM_MSF)
   {
      schi.cdsc_absaddr.msf.minute = bcd_to_int(last_sony_subcode->abs_msf[0]);
      schi.cdsc_absaddr.msf.second = bcd_to_int(last_sony_subcode->abs_msf[1]);
      schi.cdsc_absaddr.msf.frame = bcd_to_int(last_sony_subcode->abs_msf[2]);

      schi.cdsc_reladdr.msf.minute = bcd_to_int(last_sony_subcode->rel_msf[0]);
      schi.cdsc_reladdr.msf.second = bcd_to_int(last_sony_subcode->rel_msf[1]);
      schi.cdsc_reladdr.msf.frame = bcd_to_int(last_sony_subcode->rel_msf[2]);
   }
   else if (schi.cdsc_format == CDROM_LBA)
   {
      schi.cdsc_absaddr.lba = msf_to_log(last_sony_subcode->abs_msf);
      schi.cdsc_reladdr.lba = msf_to_log(last_sony_subcode->rel_msf);
   }
   
   memcpy_tofs((char *) arg, &schi, sizeof(schi));
   return 0;
}

/* Get audio data from the drive.  This is fairly complex because I
   am looking for status and data at the same time, but if I get status
   then I just look for data.  I need to get the status immediately so
   the switch from audio to data tracks will happen quickly. */
static void
read_audio_data(char          *buffer,
                unsigned char res_reg[],
                int           *res_size)
{
   unsigned int retry_count;
   int result_read;


   res_reg[0] = 0;
   res_reg[1] = 0;
   *res_size = 0;
   result_read = 0;

   /* Wait for the drive to tell us we have something */
   retry_count = jiffies + SONY_JIFFIES_TIMEOUT;
continue_read_audio_wait:
   while (   (retry_count > jiffies)
          && !(is_data_ready())
          && !(is_result_ready() || result_read))
   {
      while (handle_sony_cd_attention())
         ;

      sony_sleep();
   }
   if (!(is_data_ready()))
   {
      if (is_result_ready() && !result_read)
      {
         get_result(res_reg, res_size);

         /* Read block status and continue waiting for data. */
         if ((res_reg[0] & 0xf0) == 0x50)
         {
            result_read = 1;
            goto continue_read_audio_wait;
         }
         /* Invalid data from the drive.  Shut down the operation. */
         else if ((res_reg[0] & 0xf0) != 0x20)
         {
            printk("CDU31A: Got result that should have been error: %d\n",
                   res_reg[0]);
            res_reg[0] = 0x20;
            res_reg[1] = SONY_BAD_DATA_ERR;
            *res_size = 2;
         }
         abort_read();
      }
      else
      {
#if DEBUG
         printk("CDU31A timeout out %d\n", __LINE__);
#endif
         res_reg[0] = 0x20;
         res_reg[1] = SONY_TIMEOUT_OP_ERR;
         *res_size = 2;
         abort_read();
      }
   }
   else
   {
      clear_data_ready();

      /* If data block, then get 2340 bytes offset by 12. */
      if (sony_raw_data_mode)
      {
         insb(sony_cd_read_reg, buffer + CD_XA_HEAD, CD_FRAMESIZE_XA);
      }
      else
      {
         /* Audio gets the whole 2352 bytes. */
         insb(sony_cd_read_reg, buffer, CD_FRAMESIZE_RAW);
      }

      /* If I haven't already gotten the result, get it now. */
      if (!result_read)
      {
         /* Wait for the drive to tell us we have something */
         retry_count = jiffies + SONY_JIFFIES_TIMEOUT;
         while ((retry_count > jiffies) && !(is_result_ready()))
         {
            while (handle_sony_cd_attention())
               ;

            sony_sleep();
         }

         if (!is_result_ready())
         {
#if DEBUG
            printk("CDU31A timeout out %d\n", __LINE__);
#endif
            res_reg[0] = 0x20;
            res_reg[1] = SONY_TIMEOUT_OP_ERR;
            *res_size = 2;
            abort_read();
            return;
         }
         else
         {
            get_result(res_reg, res_size);
         }
      }

      if ((res_reg[0] & 0xf0) == 0x50)
      {
         if (   (res_reg[0] == SONY_NO_CIRC_ERR_BLK_STAT)
             || (res_reg[0] == SONY_NO_LECC_ERR_BLK_STAT)
             || (res_reg[0] == SONY_RECOV_LECC_ERR_BLK_STAT)
             || (res_reg[0] == SONY_NO_ERR_DETECTION_STAT))
         {
            /* Ok, nothing to do. */
         }
         else
         {
            printk("CDU31A: Data block error: 0x%x\n", res_reg[0]);
            res_reg[0] = 0x20;
            res_reg[1] = SONY_BAD_DATA_ERR;
            *res_size = 2;
         }
      }
      else if ((res_reg[0] & 0xf0) != 0x20)
      {
         /* The drive gave me bad status, I don't know what to do.
            Reset the driver and return an error. */
         printk("CDU31A: Invalid block status: 0x%x\n", res_reg[0]);
         restart_on_error();
         res_reg[0] = 0x20;
         res_reg[1] = SONY_BAD_DATA_ERR;
         *res_size = 2;
      }
   }
}

/* Perform a raw data read.  This will automatically detect the
   track type and read the proper data (audio or data). */
static int
read_audio(struct cdrom_read_audio *ra,
           struct inode            *inode)
{
   int retval;
   unsigned char params[2];
   unsigned char res_reg[12];
   unsigned int res_size;
   unsigned int cframe;

   /* 
    * Make sure no one else is using the driver; wait for them
    * to finish if it is so.
    */
   cli();
   while (sony_inuse)
   {
      interruptible_sleep_on(&sony_wait);
      if (current->signal & ~current->blocked)
      {
         return -EAGAIN;
      }
   }
   sony_inuse = 1;
   has_cd_task = current;
   sti();

   if (!sony_spun_up)
   {
      scd_open (inode, NULL);
   }

   /* Set the drive to do raw operations. */
   params[0] = SONY_SD_DECODE_PARAM;
   params[1] = 0x06 | sony_raw_data_mode;
   do_sony_cd_cmd(SONY_SET_DRIVE_PARAM_CMD,
                  params,
                  2,
                  res_reg,
                  &res_size);
   if ((res_size < 2) || ((res_reg[0] & 0xf0) == 0x20))
   {
      printk("CDU31A: Unable to set decode params: 0x%2.2x\n", res_reg[1]);
      return -EIO;
   }

   /* From here down, we have to goto exit_read_audio instead of returning
      because the drive parameters have to be set back to data before
      return. */

   retval = 0;
   /* start_request clears out any readahead data, so it should be safe. */
   if (start_request(ra->addr.lba, ra->nframes, 1))
   {
      retval = -EIO;
      goto exit_read_audio;
   }

   /* For every requested frame. */
   cframe = 0;
   while (cframe < ra->nframes)
   {
      read_audio_data(readahead_buffer, res_reg, &res_size);
      if ((res_reg[0] & 0xf0) == 0x20)
      {
         if (res_reg[1] == SONY_BAD_DATA_ERR)
         {
            printk("CDU31A: Data error on audio sector %d\n",
                   ra->addr.lba + cframe);
         }
         else if (res_reg[1] == SONY_ILL_TRACK_R_ERR)
         {
            /* Illegal track type, change track types and start over. */
            sony_raw_data_mode = (sony_raw_data_mode) ? 0 : 1;

            /* Set the drive mode. */
            params[0] = SONY_SD_DECODE_PARAM;
            params[1] = 0x06 | sony_raw_data_mode;
            do_sony_cd_cmd(SONY_SET_DRIVE_PARAM_CMD,
                           params,
                           2,
                           res_reg,
                           &res_size);
            if ((res_size < 2) || ((res_reg[0] & 0xf0) == 0x20))
            {
               printk("CDU31A: Unable to set decode params: 0x%2.2x\n", res_reg[1]);
               retval = -EIO;
               goto exit_read_audio;
            }

            /* Restart the request on the current frame. */
            if (start_request(ra->addr.lba + cframe, ra->nframes - cframe, 1))
            {
               retval = -EIO;
               goto exit_read_audio;
            }

            /* Don't go back to the top because don't want to get into
               and infinite loop.  A lot of code gets duplicated, but
               that's no big deal, I don't guess. */
            read_audio_data(readahead_buffer, res_reg, &res_size);
            if ((res_reg[0] & 0xf0) == 0x20)
            {
               if (res_reg[1] == SONY_BAD_DATA_ERR)
               {
                  printk("CDU31A: Data error on audio sector %d\n",
                         ra->addr.lba + cframe);
               }
               else
               {
                  printk("CDU31A: Error reading audio data on sector %d: 0x%x\n",
                         ra->addr.lba + cframe,
                         res_reg[1]);
                  retval = -EIO;
                  goto exit_read_audio;
               }
            }
            else
            {
               memcpy_tofs((char *) (ra->buf + (CD_FRAMESIZE_RAW * cframe)),
                           (char *) readahead_buffer,
                           CD_FRAMESIZE_RAW);
            }
         }
         else
         {
            printk("CDU31A: Error reading audio data on sector %d: 0x%x\n",
                   ra->addr.lba + cframe,
                   res_reg[1]);
            retval = -EIO;
            goto exit_read_audio;
         }
      }
      else
      {
         memcpy_tofs((char *) (ra->buf + (CD_FRAMESIZE_RAW * cframe)),
                     (char *) readahead_buffer,
                     CD_FRAMESIZE_RAW);
      }

      cframe++;
   }

   get_result(res_reg, &res_size);
   if ((res_reg[0] & 0xf0) == 0x20)
   {
      printk("CDU31A: Error return from audio read: 0x%x\n",
             res_reg[1]);
      retval = -EIO;
      goto exit_read_audio;
   }

exit_read_audio:

   /* Set the drive mode back to the proper one for the disk. */
   params[0] = SONY_SD_DECODE_PARAM;
   if (!sony_xa_mode)
   {
      params[1] = 0x0f;
   }
   else
   {
      params[1] = 0x07;
   }
   do_sony_cd_cmd(SONY_SET_DRIVE_PARAM_CMD,
                  params,
                  2,
                  res_reg,
                  &res_size);
   if ((res_size < 2) || ((res_reg[0] & 0xf0) == 0x20))
   {
      printk("CDU31A: Unable to reset decode params: 0x%2.2x\n", res_reg[1]);
      return -EIO;
   }

   has_cd_task = NULL;
   sony_inuse = 0;
   wake_up_interruptible(&sony_wait);

   return(retval);
}

/*
 * The big ugly ioctl handler.
 */
static int
scd_ioctl(struct inode *inode,
          struct file  *file,
          unsigned int  cmd,
          unsigned long arg)
{
   unsigned char res_reg[12];
   unsigned int res_size;
   unsigned char params[7];
   int i;


   if (!inode)
   {
      return -EINVAL;
   }

   switch (cmd)
   {
   case CDROMSTART:     /* Spin up the drive */
      do_sony_cd_cmd(SONY_SPIN_UP_CMD, NULL, 0, res_reg, &res_size);
      if ((res_size < 2) || ((res_reg[0] & 0xf0) == 0x20))
      {
         printk("Sony CDROM error 0x%2.2x (CDROMSTART)\n", res_reg[1]);
         return -EIO;
      }
      return 0;
      break;
      
   case CDROMSTOP:      /* Spin down the drive */
      do_sony_cd_cmd(SONY_AUDIO_STOP_CMD, NULL, 0, res_reg, &res_size);

      /*
       * Spin the drive down, ignoring the error if the disk was
       * already not spinning.
       */
      sony_audio_status = CDROM_AUDIO_NO_STATUS;
      do_sony_cd_cmd(SONY_SPIN_DOWN_CMD, NULL, 0, res_reg, &res_size);
      if (   ((res_size < 2) || ((res_reg[0] & 0xf0) == 0x20))
          && (res_reg[1] != SONY_NOT_SPIN_ERR))
      {
         printk("Sony CDROM error 0x%2.2x (CDROMSTOP)\n", res_reg[1]);
         return -EIO;
      }
      
      return 0;
      break;

   case CDROMPAUSE:     /* Pause the drive */
      do_sony_cd_cmd(SONY_AUDIO_STOP_CMD, NULL, 0, res_reg, &res_size);
      if ((res_size < 2) || ((res_reg[0] & 0xf0) == 0x20))
      {
         printk("Sony CDROM error 0x%2.2x (CDROMPAUSE)\n", res_reg[1]);
         return -EIO;
      }

      /* Get the current position and save it for resuming */
      if (read_subcode() < 0)
      {
         return -EIO;
      }
      cur_pos_msf[0] = last_sony_subcode->abs_msf[0];
      cur_pos_msf[1] = last_sony_subcode->abs_msf[1];
      cur_pos_msf[2] = last_sony_subcode->abs_msf[2];
      sony_audio_status = CDROM_AUDIO_PAUSED;
      return 0;
      break;

   case CDROMRESUME:    /* Start the drive after being paused */
      if (sony_audio_status != CDROM_AUDIO_PAUSED)
      {
         return -EINVAL;
      }
      
      do_sony_cd_cmd(SONY_SPIN_UP_CMD, NULL, 0, res_reg, &res_size);
      
      /* Start the drive at the saved position. */
      params[1] = cur_pos_msf[0];
      params[2] = cur_pos_msf[1];
      params[3] = cur_pos_msf[2];
      params[4] = final_pos_msf[0];
      params[5] = final_pos_msf[1];
      params[6] = final_pos_msf[2];
      params[0] = 0x03;
      do_sony_cd_cmd(SONY_AUDIO_PLAYBACK_CMD, params, 7, res_reg, &res_size);
      if ((res_size < 2) || ((res_reg[0] & 0xf0) == 0x20))
      {
         printk("Sony CDROM error 0x%2.2x (CDROMRESUME)\n", res_reg[1]);
         return -EIO;
      }
      sony_audio_status = CDROM_AUDIO_PLAY;
      return 0;
      break;

   case CDROMPLAYMSF:   /* Play starting at the given MSF address. */
      verify_area(VERIFY_READ, (char *) arg, 6);
      do_sony_cd_cmd(SONY_SPIN_UP_CMD, NULL, 0, res_reg, &res_size);
      memcpy_fromfs(&(params[1]), (void *) arg, 6);
      
      /* The parameters are given in int, must be converted */
      for (i=1; i<7; i++)
      {
         params[i] = int_to_bcd(params[i]);
      }
      params[0] = 0x03;
      do_sony_cd_cmd(SONY_AUDIO_PLAYBACK_CMD, params, 7, res_reg, &res_size);
      if ((res_size < 2) || ((res_reg[0] & 0xf0) == 0x20))
      {
         printk("Sony CDROM error 0x%2.2x (CDROMPLAYMSF)\n", res_reg[1]);
         return -EIO;
      }
      
      /* Save the final position for pauses and resumes */
      final_pos_msf[0] = params[4];
      final_pos_msf[1] = params[5];
      final_pos_msf[2] = params[6];
      sony_audio_status = CDROM_AUDIO_PLAY;
      return 0;
      break;

   case CDROMREADTOCHDR:        /* Read the table of contents header */
      {
         struct cdrom_tochdr *hdr;
         struct cdrom_tochdr loc_hdr;
         
         sony_get_toc();
         if (!sony_toc_read)
         {
            return -EIO;
         }
         
         hdr = (struct cdrom_tochdr *) arg;
         verify_area(VERIFY_WRITE, hdr, sizeof(*hdr));
         loc_hdr.cdth_trk0 = bcd_to_int(sony_toc->first_track_num);
         loc_hdr.cdth_trk1 = bcd_to_int(sony_toc->last_track_num);
         memcpy_tofs(hdr, &loc_hdr, sizeof(*hdr));
      }
      return 0;
      break;

   case CDROMREADTOCENTRY:      /* Read a given table of contents entry */
      {
         struct cdrom_tocentry *entry;
         struct cdrom_tocentry loc_entry;
         int track_idx;
         unsigned char *msf_val = NULL;
         
         sony_get_toc();
         if (!sony_toc_read)
         {
            return -EIO;
         }
         
         entry = (struct cdrom_tocentry *) arg;
         verify_area(VERIFY_READ, entry, sizeof(*entry));
         verify_area(VERIFY_WRITE, entry, sizeof(*entry));
         
         memcpy_fromfs(&loc_entry, entry, sizeof(loc_entry));
         
         /* Lead out is handled separately since it is special. */
         if (loc_entry.cdte_track == CDROM_LEADOUT)
         {
            loc_entry.cdte_adr = sony_toc->address2;
            loc_entry.cdte_ctrl = sony_toc->control2;
            msf_val = sony_toc->lead_out_start_msf;
         }
         else
         {
            track_idx = find_track(int_to_bcd(loc_entry.cdte_track));
            if (track_idx < 0)
            {
               return -EINVAL;
            }
            
            loc_entry.cdte_adr = sony_toc->tracks[track_idx].address;
            loc_entry.cdte_ctrl = sony_toc->tracks[track_idx].control;
            msf_val = sony_toc->tracks[track_idx].track_start_msf;
         }
         
         /* Logical buffer address or MSF format requested? */
         if (loc_entry.cdte_format == CDROM_LBA)
         {
            loc_entry.cdte_addr.lba = msf_to_log(msf_val);
         }
         else if (loc_entry.cdte_format == CDROM_MSF)
         {
            loc_entry.cdte_addr.msf.minute = bcd_to_int(*msf_val);
            loc_entry.cdte_addr.msf.second = bcd_to_int(*(msf_val+1));
            loc_entry.cdte_addr.msf.frame = bcd_to_int(*(msf_val+2));
         }
         memcpy_tofs(entry, &loc_entry, sizeof(*entry));
      }
      return 0;
      break;

   case CDROMPLAYTRKIND:     /* Play a track.  This currently ignores index. */
      {
         struct cdrom_ti ti;
         int track_idx;
         
         sony_get_toc();
         if (!sony_toc_read)
         {
            return -EIO;
         }
         
         verify_area(VERIFY_READ, (char *) arg, sizeof(ti));
         
         memcpy_fromfs(&ti, (char *) arg, sizeof(ti));
         if (   (ti.cdti_trk0 < sony_toc->first_track_num)
             || (ti.cdti_trk0 > sony_toc->last_track_num)
             || (ti.cdti_trk1 < ti.cdti_trk0))
         {
            return -EINVAL;
         }
         
         track_idx = find_track(int_to_bcd(ti.cdti_trk0));
         if (track_idx < 0)
         {
            return -EINVAL;
         }
         params[1] = sony_toc->tracks[track_idx].track_start_msf[0];
         params[2] = sony_toc->tracks[track_idx].track_start_msf[1];
         params[3] = sony_toc->tracks[track_idx].track_start_msf[2];
         
         /*
          * If we want to stop after the last track, use the lead-out
          * MSF to do that.
          */
         if (ti.cdti_trk1 >= bcd_to_int(sony_toc->last_track_num))
         {
            log_to_msf(msf_to_log(sony_toc->lead_out_start_msf)-1,
                       &(params[4]));
         }
         else
         {
            track_idx = find_track(int_to_bcd(ti.cdti_trk1+1));
            if (track_idx < 0)
            {
               return -EINVAL;
            }
            log_to_msf(msf_to_log(sony_toc->tracks[track_idx].track_start_msf)-1,
                       &(params[4]));
         }
         params[0] = 0x03;
         
         do_sony_cd_cmd(SONY_SPIN_UP_CMD, NULL, 0, res_reg, &res_size);
         
         do_sony_cd_cmd(SONY_AUDIO_PLAYBACK_CMD, params, 7, res_reg, &res_size);
         if ((res_size < 2) || ((res_reg[0] & 0xf0) == 0x20))
         {
            printk("Params: %x %x %x %x %x %x %x\n", params[0], params[1],
                   params[2], params[3], params[4], params[5], params[6]);
            printk("Sony CDROM error 0x%2.2x (CDROMPLAYTRKIND\n", res_reg[1]);
            return -EIO;
         }
         
         /* Save the final position for pauses and resumes */
         final_pos_msf[0] = params[4];
         final_pos_msf[1] = params[5];
         final_pos_msf[2] = params[6];
         sony_audio_status = CDROM_AUDIO_PLAY;
         return 0;
      }
     
   case CDROMSUBCHNL:   /* Get subchannel info */
      return sony_get_subchnl_info(arg);

   case CDROMVOLCTRL:   /* Volume control.  What volume does this change, anyway? */
      {
         struct cdrom_volctrl volctrl;
         
         verify_area(VERIFY_READ, (char *) arg, sizeof(volctrl));
         
         memcpy_fromfs(&volctrl, (char *) arg, sizeof(volctrl));
         params[0] = SONY_SD_AUDIO_VOLUME;
         params[1] = volctrl.channel0;
         params[2] = volctrl.channel1;
         do_sony_cd_cmd(SONY_SET_DRIVE_PARAM_CMD, params, 3, res_reg, &res_size);
         if ((res_size < 2) || ((res_reg[0] & 0xf0) == 0x20))
         {
            printk("Sony CDROM error 0x%2.2x (CDROMVOLCTRL)\n", res_reg[1]);
            return -EIO;
         }
      }
      return 0;

   case CDROMEJECT:     /* Eject the drive */
      do_sony_cd_cmd(SONY_AUDIO_STOP_CMD, NULL, 0, res_reg, &res_size);
      do_sony_cd_cmd(SONY_SPIN_DOWN_CMD, NULL, 0, res_reg, &res_size);

      sony_audio_status = CDROM_AUDIO_INVALID;
      do_sony_cd_cmd(SONY_EJECT_CMD, NULL, 0, res_reg, &res_size);
      if ((res_size < 2) || ((res_reg[0] & 0xf0) == 0x20))
      {
         printk("Sony CDROM error 0x%2.2x (CDROMEJECT)\n", res_reg[1]);
         return -EIO;
      }
      return 0;
      break;
     
    case CDROMREADAUDIO:      /* Read 2352 byte audio tracks and 2340 byte
				 raw data tracks. */
      {
         struct cdrom_read_audio ra;


         sony_get_toc();
         if (!sony_toc_read)
         {
            return -EIO;
         }
         
         verify_area(VERIFY_READ, (char *) arg, sizeof(ra));
         memcpy_fromfs(&ra, (char *) arg, sizeof(ra));

         verify_area(VERIFY_WRITE, ra.buf, CD_FRAMESIZE_RAW * ra.nframes);

         if (ra.addr_format == CDROM_LBA)
         {
            if (   (ra.addr.lba >= sony_toc->lead_out_start_lba)
                || (ra.addr.lba + ra.nframes >= sony_toc->lead_out_start_lba))
            {
               return -EINVAL;
            }
         }
         else if (ra.addr_format == CDROM_MSF)
         {
            if (   (ra.addr.msf.minute >= 75)
                || (ra.addr.msf.second >= 60)
                || (ra.addr.msf.frame >= 75))
            {
               return -EINVAL;
            }

            ra.addr.lba = (  (ra.addr.msf.minute * 4500)
                           + (ra.addr.msf.second * 75)
                           + ra.addr.msf.frame);
            if (   (ra.addr.lba >= sony_toc->lead_out_start_lba)
                || (ra.addr.lba + ra.nframes >= sony_toc->lead_out_start_lba))
            {
               return -EINVAL;
            }

            /* I know, this can go negative on an unsigned.  However,
               the first thing done to the data is to add this value,
               so this should compensate and allow direct msf access. */
            ra.addr.lba -= LOG_START_OFFSET;
         }
         else
         {
            return -EINVAL;
         }

         return(read_audio(&ra, inode));
      }
      return 0;
      break;

   default:
      return -EINVAL;
   }
}


/*
 * Open the drive for operations.  Spin the drive up and read the table of
 * contents if these have not already been done.
 */
static int
scd_open(struct inode *inode,
         struct file *filp)
{
   unsigned char res_reg[12];
   unsigned int res_size;
   int num_spin_ups;
   unsigned char params[2];


   if ((filp) && filp->f_mode & 2)
      return -EROFS;

   if (!sony_spun_up)
   {
      num_spin_ups = 0;

respinup_on_open:
      do_sony_cd_cmd(SONY_SPIN_UP_CMD, NULL, 0, res_reg, &res_size);

      /* The drive sometimes returns error 0.  I don't know why, but ignore
         it.  It seems to mean the drive has already done the operation. */
      if ((res_size < 2) || ((res_reg[0] != 0) && (res_reg[1] != 0)))
      {
         printk("Sony CDROM error 0x%2.2x (scd_open, spin up)\n", res_reg[1]);
         return -EIO;
      }
      
      do_sony_cd_cmd(SONY_READ_TOC_CMD, NULL, 0, res_reg, &res_size);

      /* The drive sometimes returns error 0.  I don't know why, but ignore
         it.  It seems to mean the drive has already done the operation. */
      if ((res_size < 2) || ((res_reg[0] != 0) && (res_reg[1] != 0)))
      {
         /* If the drive is already playing, its ok.  */
         if ((res_reg[1] == SONY_AUDIO_PLAYING_ERR) || (res_reg[1] == 0))
         {
            goto drive_spinning;
         }

         /* If the drive says it is not spun up (even though we just did it!)
            then retry the operation at least a few times. */
         if (   (res_reg[1] == SONY_NOT_SPIN_ERR)
             && (num_spin_ups < MAX_CDU31A_RETRIES))
         {
            num_spin_ups++;
            goto respinup_on_open;
         }

         printk("Sony CDROM error 0x%2.2x (scd_open, read toc)\n", res_reg[1]);
         do_sony_cd_cmd(SONY_SPIN_DOWN_CMD, NULL, 0, res_reg, &res_size);
         
         return -EIO;
      }

      sony_get_toc();
      if (!sony_toc_read)
      {
         do_sony_cd_cmd(SONY_SPIN_DOWN_CMD, NULL, 0, res_reg, &res_size);
         return -EIO;
      }

      /* For XA on the CDU31A only, we have to do special reads.
         The CDU33A handles XA automagically. */
      if (   (sony_toc->disk_type == SONY_XA_DISK_TYPE)
          && (!is_double_speed))
      {
         params[0] = SONY_SD_DECODE_PARAM;
         params[1] = 0x07;
         do_sony_cd_cmd(SONY_SET_DRIVE_PARAM_CMD,
                        params,
                        2,
                        res_reg,
                        &res_size);
         if ((res_size < 2) || ((res_reg[0] & 0xf0) == 0x20))
         {
            printk("CDU31A: Unable to set XA params: 0x%2.2x\n", res_reg[1]);
         }
         sony_xa_mode = 1;
      }
      /* A non-XA disk.  Set the parms back if necessary. */
      else if (sony_xa_mode)
      {
         params[0] = SONY_SD_DECODE_PARAM;
         params[1] = 0x0f;
         do_sony_cd_cmd(SONY_SET_DRIVE_PARAM_CMD,
                        params,
                        2,
                        res_reg,
                        &res_size);
         if ((res_size < 2) || ((res_reg[0] & 0xf0) == 0x20))
         {
            printk("CDU31A: Unable to reset XA params: 0x%2.2x\n", res_reg[1]);
         }
         sony_xa_mode = 0;
      }

      sony_spun_up = 1;
   }

drive_spinning:

   /* If filp is not NULL (standard open), try a disk change. */
   if (filp)
   {
      check_disk_change(inode->i_rdev);
   }

   sony_usage++;

   return 0;
}


/*
 * Close the drive.  Spin it down if no task is using it.  The spin
 * down will fail if playing audio, so audio play is OK.
 */
static void
scd_release(struct inode *inode,
         struct file *filp)
{
   unsigned char res_reg[12];
   unsigned int  res_size;


   if (sony_usage > 0)
   {
      sony_usage--;
   }
   if (sony_usage == 0)
   {
      sync_dev(inode->i_rdev);
      do_sony_cd_cmd(SONY_SPIN_DOWN_CMD, NULL, 0, res_reg, &res_size);

      sony_spun_up = 0;
   }
}


static struct file_operations scd_fops = {
   NULL,                   /* lseek - default */
   block_read,             /* read - general block-dev read */
   block_write,            /* write - general block-dev write */
   NULL,                   /* readdir - bad */
   NULL,                   /* select */
   scd_ioctl,              /* ioctl */
   NULL,                   /* mmap */
   scd_open,               /* open */
   scd_release,            /* release */
   NULL,                   /* fsync */
   NULL,                   /* fasync */
   scd_disk_change,        /* media_change */
   NULL                    /* revalidate */
};


/* The different types of disc loading mechanisms supported */
static char *load_mech[] = { "caddy", "tray", "pop-up", "unknown" };

static void
get_drive_configuration(unsigned short base_io,
                        unsigned char res_reg[],
                        unsigned int *res_size)
{
   int retry_count;


   /* Set the base address */
   sony_cd_base_io = base_io;

   /* Set up all the register locations */
   sony_cd_cmd_reg = sony_cd_base_io + SONY_CMD_REG_OFFSET;
   sony_cd_param_reg = sony_cd_base_io + SONY_PARAM_REG_OFFSET;
   sony_cd_write_reg = sony_cd_base_io + SONY_WRITE_REG_OFFSET;
   sony_cd_control_reg = sony_cd_base_io + SONY_CONTROL_REG_OFFSET;
   sony_cd_status_reg = sony_cd_base_io + SONY_STATUS_REG_OFFSET;
   sony_cd_result_reg = sony_cd_base_io + SONY_RESULT_REG_OFFSET;
   sony_cd_read_reg = sony_cd_base_io + SONY_READ_REG_OFFSET;
   sony_cd_fifost_reg = sony_cd_base_io + SONY_FIFOST_REG_OFFSET;

   /*
    * Check to see if anything exists at the status register location.
    * I don't know if this is a good way to check, but it seems to work
    * ok for me.
    */
   if (read_status_register() != 0xff)
   {
      /*
       * Reset the drive and wait for attention from it (to say its reset).
       * If you don't wait, the next operation will probably fail.
       */
      reset_drive();
      retry_count = jiffies + SONY_RESET_TIMEOUT;
      while ((retry_count > jiffies) && (!is_attention()))
      {
         sony_sleep();
      }

#if 0
      /* If attention is never seen probably not a CDU31a present */
      if (!is_attention())
      {
         res_reg[0] = 0x20;
         return;
      }
#endif

      /*
       * Get the drive configuration.
       */
      do_sony_cd_cmd(SONY_REQ_DRIVE_CONFIG_CMD,
                     NULL,
                     0,
                     (unsigned char *) res_reg,
                     res_size);
      return;
   }

   /* Return an error */
   res_reg[0] = 0x20;
}

/*
 * Set up base I/O and interrupts, called from main.c.
 */
void
cdu31a_setup(char *strings,
	     int  *ints)
{
   if (ints[0] > 0)
   {
      sony_cd_base_io = ints[1];
   }
   if (ints[0] > 1)
   {
      irq_used = ints[2];
   }
   if ((strings != NULL) && (*strings != '\0'))
   {
      if (strcmp(strings, "PAS") == 0)
      {
	 sony_pas_init = 1;
      }
      else
      {
	 printk("CDU31A: Unknown interface type: %s\n", strings);
      }
   }
}

static int cdu31a_block_size;

/*
 * Initialize the driver.
 */
unsigned long
cdu31a_init(unsigned long mem_start, unsigned long mem_end)
{
   struct s_sony_drive_config drive_config;
   unsigned int res_size;
   int i;
   int drive_found;
   int tmp_irq;


   /*
    * According to Alex Freed (freed@europa.orion.adobe.com), this is
    * required for the Fusion CD-16 package.  If the sound driver is
    * loaded, it should work fine, but just in case...
    *
    * The following turn on the CD-ROM interface for a Fusion CD-16.
    */
   if (sony_pas_init)
   {
      outb(0xbc, 0x9a01);
      outb(0xe2, 0x9a01);
   }

   drive_found = 0;

   /* Setting the base I/O address to 0xffff will disable it. */
   if (sony_cd_base_io == 0xffff)
   {
   }
   else if (sony_cd_base_io != 0)
   {
      tmp_irq = irq_used; /* Need IRQ 0 because we can't sleep here. */
      irq_used = 0;

      get_drive_configuration(sony_cd_base_io,
			      drive_config.exec_status,
			      &res_size);
      if ((res_size > 2) && ((drive_config.exec_status[0] & 0xf0) == 0x00))
      {
	 drive_found = 1;
      }

      irq_used = tmp_irq;
   }
   else
   {
      irq_used = 0;
      i = 0;
      while (   (cdu31a_addresses[i].base != 0)
	     && (!drive_found))
      {
	 if (check_region(cdu31a_addresses[i].base, 4)) {
	    i++;
	    continue;
	 }
	 get_drive_configuration(cdu31a_addresses[i].base,
				 drive_config.exec_status,
				 &res_size);
	 if ((res_size > 2) && ((drive_config.exec_status[0] & 0xf0) == 0x00))
	 {
	    drive_found = 1;
	    irq_used = cdu31a_addresses[i].int_num;
	 }
	 else
	 {
	    i++;
	 }
      }
   }

   if (drive_found)
   {
      request_region(sony_cd_base_io, 4,"cdu31a");
      
      if (register_blkdev(MAJOR_NR,"cdu31a",&scd_fops))
      {
	 printk("Unable to get major %d for CDU-31a\n", MAJOR_NR);
	 return mem_start;
      }

      if (SONY_HWC_DOUBLE_SPEED(drive_config))
      {
	 is_double_speed = 1;
      }

      /* A negative irq_used will attempt an autoirq. */
      if (irq_used < 0)
      {
	 autoirq_setup(0);
	 enable_interrupts();
	 reset_drive();
	 tmp_irq = autoirq_report(10);
	 disable_interrupts();
	 
         irq_used = 0;
	 set_drive_params();
	 irq_used = tmp_irq;
      }
      else
      {
         tmp_irq = irq_used; /* Need IRQ 0 because we can't sleep here. */
         irq_used = 0;

	 set_drive_params();

         irq_used = tmp_irq;
      }
      
      if (irq_used > 0)
      {
	 if (request_irq(irq_used, cdu31a_interrupt, SA_INTERRUPT, "cdu31a"))
	 {
	    printk("Unable to grab IRQ%d for the CDU31A driver\n", irq_used);
	    irq_used = 0;
	 }
      }
      
      printk("Sony I/F CDROM : %8.8s %16.16s %8.8s\n",
	     drive_config.vendor_id,
	     drive_config.product_id,
	     drive_config.product_rev_level);
      printk("  Capabilities: %s",
	     load_mech[SONY_HWC_GET_LOAD_MECH(drive_config)]);
      if (SONY_HWC_AUDIO_PLAYBACK(drive_config))
      {
	 printk(", audio");
      }
      if (SONY_HWC_EJECT(drive_config))
      {
	 printk(", eject");
      }
      if (SONY_HWC_LED_SUPPORT(drive_config))
      {
	 printk(", LED");
      }
      if (SONY_HWC_ELECTRIC_VOLUME(drive_config))
      {
	 printk(", elec. Vol");
      }
      if (SONY_HWC_ELECTRIC_VOLUME_CTL(drive_config))
      {
	 printk(", sep. Vol");
      }
      if (is_double_speed)
      {
	 printk(", double speed");
      }
      if (irq_used > 0)
      {
	 printk(", irq %d", irq_used);
      }
      printk("\n");

      blk_dev[MAJOR_NR].request_fn = DEVICE_REQUEST;
      read_ahead[MAJOR_NR] = CDU31A_READAHEAD;
      cdu31a_block_size = 1024; /* 1kB default block size */
      /* use 'mount -o block=2048' */
      blksize_size[MAJOR_NR] = &cdu31a_block_size;
      
      last_sony_subcode = (struct s_sony_subcode *) mem_start;
      mem_start += sizeof(*last_sony_subcode);
      readahead_buffer = (unsigned char *) mem_start;
      mem_start += CD_FRAMESIZE_RAW;
      sony_toc = (struct s_sony_session_toc *) mem_start;
      mem_start += sizeof(struct s_sony_session_toc);
   }


   disk_changed = 1;
   
   return mem_start;
}
