text: /*
   * /dev/nvram driver for Power Macintosh.
   */
  
  #define NVRAM_VERSION "1.0"
  
  #include <linux/module.h>
  
  #include <linux/types.h>
  #include <linux/errno.h>
  #include <linux/fs.h>
  #include <linux/miscdevice.h>
  #include <linux/fcntl.h>
  #include <linux/nvram.h>
  #include <linux/init.h>
  #include <asm/uaccess.h>
  #include <asm/nvram.h>
  
  #define NVRAM_SIZE	8192
  
  static long long nvram_llseek(struct file *file, loff_t offset, int origin)
  {
  	switch (origin) {
  	case 1:
  		offset += file->f_pos;
  		break;
  	case 2:
  		offset += NVRAM_SIZE;
  		break;
  	}
  	if (offset < 0)
  		return -EINVAL;
  	file->f_pos = offset;
  	return file->f_pos;
  }
  
  static ssize_t read_nvram(struct file *file, char *buf,
  			  size_t count, loff_t *ppos)
  {
  	unsigned int i;
  	char *p = buf;
  
  	if (verify_area(VERIFY_WRITE, buf, count))
  		return -EFAULT;
  	if (*ppos >= NVRAM_SIZE)
  		return 0;
  	for (i = *ppos; count > 0 && i < NVRAM_SIZE; ++i, ++p, --count)
  		if (__put_user(nvram_read_byte(i), p))
  			return -EFAULT;
  	*ppos = i;
  	return p - buf;
  }
  
  static ssize_t write_nvram(struct file *file, const char *buf,
  			   size_t count, loff_t *ppos)
  {
  	unsigned int i;
  	const char *p = buf;
  	char c;
  
  	if (verify_area(VERIFY_READ, buf, count))
  		return -EFAULT;
  	if (*ppos >= NVRAM_SIZE)
  		return 0;
  	for (i = *ppos; count > 0 && i < NVRAM_SIZE; ++i, ++p, --count) {
  		if (__get_user(c, p))
  			return -EFAULT;
  		nvram_write_byte(c, i);
  	}
  	*ppos = i;
  	return p - buf;
  }
  
  static int nvram_ioctl(struct inode *inode, struct file *file,
  	unsigned int cmd, unsigned long arg)
  {
  	switch(cmd) {
  		case PMAC_NVRAM_GET_OFFSET:
  		{
  			int part, offset;
  			if (copy_from_user(&part,(void*)arg,sizeof(part))!=0)
  				return -EFAULT;
  			if (part < pmac_nvram_OF || part > pmac_nvram_NR)
  				return -EINVAL;
  			offset = pmac_get_partition(part);
  			if (copy_to_user((void*)arg,&offset,sizeof(offset))!=0)
  				return -EFAULT;
  			break;
  		}
  
  		default:
  			return -EINVAL;
  	}
  
  	return 0;
  }
  
  struct file_operations nvram_fops = {
  	owner:		THIS_MODULE,
  	llseek:		nvram_llseek,
  	read:		read_nvram,
  	write:		write_nvram,
  	ioctl:		nvram_ioctl,
  };
  
  static struct miscdevice nvram_dev = {
  	NVRAM_MINOR,
  	"nvram",
  	&nvram_fops
  };
  
  int __init nvram_init(void)
  {
  	printk(KERN_INFO "Macintosh non-volatile memory driver v%s\n",
  		NVRAM_VERSION);
  	misc_register(&nvram_dev);
  	return 0;
  }
  
  void __exit nvram_cleanup(void)
  {
          misc_deregister( &nvram_dev );
  }
  
  module_init(nvram_init);
  module_exit(nvram_cleanup);
  