/* * linux/fs/devices.c * * (C) 1993 Matthias Urlichs -- collected common code and tables. * * Copyright (C) 1991, 1992 Linus Torvalds */ #include #include #include #include #include #include #include #include struct device_struct { const char * name; struct file_operations * fops; }; static struct device_struct chrdevs[MAX_CHRDEV] = { { NULL, NULL }, }; static struct device_struct blkdevs[MAX_BLKDEV] = { { NULL, NULL }, }; struct file_operations * get_blkfops(unsigned int major) { if (major >= MAX_BLKDEV) return NULL; return blkdevs[major].fops; } struct file_operations * get_chrfops(unsigned int major) { if (major >= MAX_CHRDEV) return NULL; return chrdevs[major].fops; } int register_chrdev(unsigned int major, const char * name, struct file_operations *fops) { if (major >= MAX_CHRDEV) return -EINVAL; if (chrdevs[major].fops) return -EBUSY; chrdevs[major].name = name; chrdevs[major].fops = fops; return 0; } int register_blkdev(unsigned int major, const char * name, struct file_operations *fops) { if (major >= MAX_BLKDEV) return -EINVAL; if (blkdevs[major].fops) return -EBUSY; blkdevs[major].name = name; blkdevs[major].fops = fops; return 0; } int unregister_chrdev(unsigned int major, const char * name) { if (major >= MAX_CHRDEV) return -EINVAL; if (!chrdevs[major].fops) return -EINVAL; if (strcmp(chrdevs[major].name, name)) return -EINVAL; chrdevs[major].name = NULL; chrdevs[major].fops = NULL; return 0; } int unregister_blkdev(unsigned int major, const char * name) { if (major >= MAX_BLKDEV) return -EINVAL; if (!blkdevs[major].fops) return -EINVAL; if (strcmp(blkdevs[major].name, name)) return -EINVAL; blkdevs[major].name = NULL; blkdevs[major].fops = NULL; return 0; } /* * Called every time a block special file is opened */ int blkdev_open(struct inode * inode, struct file * filp) { int i; i = MAJOR(inode->i_rdev); if (i >= MAX_BLKDEV || !blkdevs[i].fops) return -ENODEV; filp->f_op = blkdevs[i].fops; if (filp->f_op->open) return filp->f_op->open(inode,filp); return 0; } /* * Dummy default file-operations: the only thing this does * is contain the open that then fills in the correct operations * depending on the special file... */ struct file_operations def_blk_fops = { NULL, /* lseek */ NULL, /* read */ NULL, /* write */ NULL, /* readdir */ NULL, /* select */ NULL, /* ioctl */ NULL, /* mmap */ blkdev_open, /* open */ NULL, /* release */ }; struct inode_operations blkdev_inode_operations = { &def_blk_fops, /* default file operations */ NULL, /* create */ NULL, /* lookup */ NULL, /* link */ NULL, /* unlink */ NULL, /* symlink */ NULL, /* mkdir */ NULL, /* rmdir */ NULL, /* mknod */ NULL, /* rename */ NULL, /* readlink */ NULL, /* follow_link */ NULL, /* bmap */ NULL, /* truncate */ NULL /* permission */ }; /* * Called every time a character special file is opened */ int chrdev_open(struct inode * inode, struct file * filp) { int i; i = MAJOR(inode->i_rdev); if (i >= MAX_CHRDEV || !chrdevs[i].fops) return -ENODEV; filp->f_op = chrdevs[i].fops; if (filp->f_op->open) return filp->f_op->open(inode,filp); return 0; } /* * Dummy default file-operations: the only thing this does * is contain the open that then fills in the correct operations * depending on the special file... */ struct file_operations def_chr_fops = { NULL, /* lseek */ NULL, /* read */ NULL, /* write */ NULL, /* readdir */ NULL, /* select */ NULL, /* ioctl */ NULL, /* mmap */ chrdev_open, /* open */ NULL, /* release */ }; struct inode_operations chrdev_inode_operations = { &def_chr_fops, /* default file operations */ NULL, /* create */ NULL, /* lookup */ NULL, /* link */ NULL, /* unlink */ NULL, /* symlink */ NULL, /* mkdir */ NULL, /* rmdir */ NULL, /* mknod */ NULL, /* rename */ NULL, /* readlink */ NULL, /* follow_link */ NULL, /* bmap */ NULL, /* truncate */ NULL /* permission */ };