/*
 * This code is based very heavily (read pretty
 * much copied verbatim) from the Linux Kernel
 * Module Programming Guide.
 *
 * Parts of the Elan specific bits were gleaned
 * from the sc520 watcdog driver
 */


#include <linux/kernel.h>   
#include <linux/module.h>   
#include <linux/proc_fs.h>
#include <asm/uaccess.h>
#include <asm/io.h>

MODULE_LICENSE( "GPL" );

static __u16 *mmcrbase,*pio_fun,*pio_dir,*pio_dat;


#define BUFSIZE 32


static ssize_t led_output(
       struct file *file,   /* The file read */
       char *buf,           /* The buffer to put
			     * data to (in the
			     * user segment) */
       size_t len,          /* The length of the
			       buffer */
       loff_t *offset)      /* Offset in the file
			       - ignore */
{
  __u16 dat = readw( pio_dat );
  char my_buffer[BUFSIZE];  
  static int finished = 0;
  int i;

  if ( finished ){
    finished = 0;
    return 0;
  }

  if ( dat & 0x200 ){
    len = sprintf( my_buffer, "on\n" );
  }
  else {
    len = sprintf( my_buffer, "off\n" );
  }

  for(i=0; i < len && my_buffer[i]; i++  ){
    put_user( my_buffer[i], buf + i );
  }
 
  finished = 1;
  
  return i;
}

static ssize_t led_input(
     struct file *file,   /* The file itself */
     const char *buf,     /* The buffer with
			     input */
     size_t length,       /* The buffer's
			     length */
     loff_t *offset)      /* offset to file -
			     ignore */
{
  int i;
  char my_buffer[BUFSIZE];
  __u16 dat = readw( pio_dat );

  for(i=0; i<BUFSIZE-1 && i<length; i++)
    get_user(my_buffer[i], buf+i);
  my_buffer[i] = '\0';    

  /*
   * Now decide what to do...
   */

  if ( strncmp( my_buffer, "on", 2 ) == 0 ){
    dat |= 0x200;
  }
  else if ( strncmp( my_buffer,"off",3)==0){
    dat &= ~0x200;
  }
  else if ( strncmp( my_buffer,"toggle",6)==0){
    dat ^= 0x200;
  }
  writew( dat, pio_dat );
  
  return i;
}



static struct proc_dir_entry *pde;


static int led_permission(
    struct inode *inode, 
    int op)
{
  if (op==4 || (op == 2 && current->eui==pde->uid))
    return 0; 

  /* If it's anything else, access is denied */
  return -EACCES;
}


static int led_open(
	       struct inode *inode, 
	       struct file *file)
{
  MOD_INC_USE_COUNT; 
  return 0;
}


static int led_close(
	       struct inode *inode, 
	       struct file *file)
{
  MOD_DEC_USE_COUNT;
  return 0;  /* success */
}


static struct file_operations file_ops =
  {
    NULL,         /* module owner */
    NULL,         /* llseek */
    led_output,   /* "read" from the file */
    led_input,    /* "write" to the file */
    NULL,         /* readdir */
    NULL,         /* poll */
    NULL,         /* ioctl */
    NULL,         /* mmap */
    led_open,     /* Somebody opened the file */
    NULL,         /* flush */
    led_close,    /* release */
    NULL,         /* fsync */
    NULL,         /* fasync */
    NULL,         /* lock */
    NULL,         /* readv */
    NULL,         /* writev */
    NULL,         /* sendpage */
    NULL          /* get_unmapped_area */
  };



static struct inode_operations inode_ops =
  {
    NULL, /* create */
    NULL, /* lookup */
    NULL, /* link */
    NULL, /* unlink */
    NULL, /* symlink */
    NULL, /* mkdir */
    NULL, /* rmdir */
    NULL, /* mknod */
    NULL, /* rename */
    NULL, /* readlink */
    NULL, /* follow_link */
    NULL, /* truncate */
    led_permission, /* check for permissions */
    NULL, /* revalidate */
    NULL, /* setattr */
    NULL  /* getattr */
  };




static int init()
{
  if ( (pde = create_proc_entry( 
               "led", 
	       S_IFREG|S_IRUGO|S_IWUSR, 
	       &proc_root)) ){

    unsigned long cbar = inl_p(0xfffc);
    __u16 fun, dir, dat;


    pde->size = BUFSIZE;
    pde->proc_iops = &inode_ops;
    pde->proc_fops = &file_ops;

    if ( cbar & 0x80000000 ){
      mmcrbase = (__u16 *)(cbar & 0x3FFFFFFF);
    }
    else {
      mmcrbase = (__u16 *)0xFFFEF000;
    }
    
    pio_fun = (__u16 *)((char *)mmcrbase + 0xc20 );
    pio_fun = ioremap( (unsigned long)pio_fun ,2 );
    pio_dir = (__u16 *)((char *)mmcrbase + 0xc2a );
    pio_dir = ioremap( (unsigned long)pio_dir ,2 );
    pio_dat = (__u16 *)((char *)mmcrbase + 0xc30 );
    pio_dat = ioremap( (unsigned long)pio_dat ,2 );

    /*
     * Make sure PIO12 is set as an output
     * (initially off)
     */
    dir = readw( pio_dir );
    fun = readw( pio_fun );
    dat = readw( pio_dat );

    dir |=  0x200;
    fun &= ~0x200;
    dat &= ~0x200;

    writew( fun, pio_fun );
    writew( dir, pio_dir );
    writew( dat, pio_dat );
      
    return 0;
  }
  return -ENOMEM;
}


/* Cleanup - unregister our file from /proc */
static void cleanup()
{

  iounmap( pio_fun );
  iounmap( pio_dat );
  iounmap( pio_dir );

  remove_proc_entry(pde->name, &proc_root );
}  


module_init(init);
module_exit(cleanup);