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[/] [or1k/] [trunk/] [linux/] [linux-2.4/] [fs/] [devices.c] - Rev 1774
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/* * linux/fs/devices.c * * (C) 1993 Matthias Urlichs -- collected common code and tables. * * Copyright (C) 1991, 1992 Linus Torvalds * * Added kerneld support: Jacques Gelinas and Bjorn Ekwall * (changed to kmod) */ #include <linux/config.h> #include <linux/fs.h> #include <linux/major.h> #include <linux/string.h> #include <linux/sched.h> #include <linux/stat.h> #include <linux/fcntl.h> #include <linux/errno.h> #include <linux/module.h> #include <linux/smp_lock.h> #ifdef CONFIG_KMOD #include <linux/kmod.h> #include <linux/tty.h> /* serial module kmod load support */ struct tty_driver *get_tty_driver(kdev_t device); #define isa_tty_dev(ma) (ma == TTY_MAJOR || ma == TTYAUX_MAJOR) #define need_serial(ma,mi) (get_tty_driver(MKDEV(ma,mi)) == NULL) #endif struct device_struct { const char * name; struct file_operations * fops; }; static rwlock_t chrdevs_lock = RW_LOCK_UNLOCKED; static struct device_struct chrdevs[MAX_CHRDEV]; extern int get_blkdev_list(char *); int get_device_list(char * page) { int i; int len; len = sprintf(page, "Character devices:\n"); read_lock(&chrdevs_lock); for (i = 0; i < MAX_CHRDEV ; i++) { if (chrdevs[i].fops) { len += sprintf(page+len, "%3d %s\n", i, chrdevs[i].name); } } read_unlock(&chrdevs_lock); len += get_blkdev_list(page+len); return len; } /* Return the function table of a device. Load the driver if needed. Increment the reference count of module in question. */ static struct file_operations * get_chrfops(unsigned int major, unsigned int minor) { struct file_operations *ret = NULL; if (!major || major >= MAX_CHRDEV) return NULL; read_lock(&chrdevs_lock); ret = fops_get(chrdevs[major].fops); read_unlock(&chrdevs_lock); #ifdef CONFIG_KMOD if (ret && isa_tty_dev(major)) { lock_kernel(); if (need_serial(major,minor)) { /* Force request_module anyway, but what for? */ fops_put(ret); ret = NULL; } unlock_kernel(); } if (!ret) { char name[20]; sprintf(name, "char-major-%d", major); request_module(name); read_lock(&chrdevs_lock); ret = fops_get(chrdevs[major].fops); read_unlock(&chrdevs_lock); } #endif return ret; } int register_chrdev(unsigned int major, const char * name, struct file_operations *fops) { if (major == 0) { write_lock(&chrdevs_lock); for (major = MAX_CHRDEV-1; major > 0; major--) { if (chrdevs[major].fops == NULL) { chrdevs[major].name = name; chrdevs[major].fops = fops; write_unlock(&chrdevs_lock); return major; } } write_unlock(&chrdevs_lock); return -EBUSY; } if (major >= MAX_CHRDEV) return -EINVAL; write_lock(&chrdevs_lock); if (chrdevs[major].fops && chrdevs[major].fops != fops) { write_unlock(&chrdevs_lock); return -EBUSY; } chrdevs[major].name = name; chrdevs[major].fops = fops; write_unlock(&chrdevs_lock); return 0; } int unregister_chrdev(unsigned int major, const char * name) { if (major >= MAX_CHRDEV) return -EINVAL; write_lock(&chrdevs_lock); if (!chrdevs[major].fops || strcmp(chrdevs[major].name, name)) { write_unlock(&chrdevs_lock); return -EINVAL; } chrdevs[major].name = NULL; chrdevs[major].fops = NULL; write_unlock(&chrdevs_lock); return 0; } /* * Called every time a character special file is opened */ int chrdev_open(struct inode * inode, struct file * filp) { int ret = -ENODEV; filp->f_op = get_chrfops(MAJOR(inode->i_rdev), MINOR(inode->i_rdev)); if (filp->f_op) { ret = 0; if (filp->f_op->open != NULL) { lock_kernel(); ret = filp->f_op->open(inode,filp); unlock_kernel(); } } return ret; } /* * 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... */ static struct file_operations def_chr_fops = { open: chrdev_open, }; /* * Print device name (in decimal, hexadecimal or symbolic) * Note: returns pointer to static data! */ const char * kdevname(kdev_t dev) { static char buffer[32]; sprintf(buffer, "%02x:%02x", MAJOR(dev), MINOR(dev)); return buffer; } const char * cdevname(kdev_t dev) { static char buffer[32]; const char * name = chrdevs[MAJOR(dev)].name; if (!name) name = "unknown-char"; sprintf(buffer, "%s(%d,%d)", name, MAJOR(dev), MINOR(dev)); return buffer; } static int sock_no_open(struct inode *irrelevant, struct file *dontcare) { return -ENXIO; } static struct file_operations bad_sock_fops = { open: sock_no_open }; void init_special_inode(struct inode *inode, umode_t mode, int rdev) { inode->i_mode = mode; if (S_ISCHR(mode)) { inode->i_fop = &def_chr_fops; inode->i_rdev = to_kdev_t(rdev); inode->i_cdev = cdget(rdev); } else if (S_ISBLK(mode)) { inode->i_fop = &def_blk_fops; inode->i_rdev = to_kdev_t(rdev); } else if (S_ISFIFO(mode)) inode->i_fop = &def_fifo_fops; else if (S_ISSOCK(mode)) inode->i_fop = &bad_sock_fops; else printk(KERN_DEBUG "init_special_inode: bogus imode (%o)\n", mode); }
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