1 /* 2 * linux/drivers/char/misc.c 3 * 4 * Generic misc open routine by Johan Myreen 5 * 6 * Based on code from Linus 7 * 8 * Teemu Rantanen's Microsoft Busmouse support and Derrick Cole's 9 * changes incorporated into 0.97pl4 10 * by Peter Cervasio (pete%q106fm.uucp@wupost.wustl.edu) (08SEP92) 11 * See busmouse.c for particulars. 12 * 13 * Made things a lot mode modular - easy to compile in just one or two 14 * of the misc drivers, as they are now completely independent. Linus. 15 * 16 * Support for loadable modules. 8-Sep-95 Philip Blundell <pjb27@cam.ac.uk> 17 * 18 * Fixed a failing symbol register to free the device registration 19 * Alan Cox <alan@lxorguk.ukuu.org.uk> 21-Jan-96 20 * 21 * Dynamic minors and /proc/mice by Alessandro Rubini. 26-Mar-96 22 * 23 * Renamed to misc and miscdevice to be more accurate. Alan Cox 26-Mar-96 24 * 25 * Handling of mouse minor numbers for kerneld: 26 * Idea by Jacques Gelinas <jack@solucorp.qc.ca>, 27 * adapted by Bjorn Ekwall <bj0rn@blox.se> 28 * corrected by Alan Cox <alan@lxorguk.ukuu.org.uk> 29 * 30 * Changes for kmod (from kerneld): 31 * Cyrus Durgin <cider@speakeasy.org> 32 * 33 * Added devfs support. Richard Gooch <rgooch@atnf.csiro.au> 10-Jan-1998 34 */ 35 36 #include <linux/module.h> 37 #include <linux/config.h> 38 39 #include <linux/fs.h> 40 #include <linux/errno.h> 41 #include <linux/miscdevice.h> 42 #include <linux/kernel.h> 43 #include <linux/major.h> 44 #include <linux/slab.h> 45 #include <linux/proc_fs.h> 46 #include <linux/seq_file.h> 47 #include <linux/devfs_fs_kernel.h> 48 #include <linux/stat.h> 49 #include <linux/init.h> 50 #include <linux/device.h> 51 #include <linux/tty.h> 52 #include <linux/kmod.h> 53 54 /* 55 * Head entry for the doubly linked miscdevice list 56 */ 57 static LIST_HEAD(misc_list); 58 static DECLARE_MUTEX(misc_sem); 59 60 /* 61 * Assigned numbers, used for dynamic minors 62 */ 63 #define DYNAMIC_MINORS 64 /* like dynamic majors */ 64 static unsigned char misc_minors[DYNAMIC_MINORS / 8]; 65 66 extern int rtc_DP8570A_init(void); 67 extern int rtc_MK48T08_init(void); 68 extern int pmu_device_init(void); 69 extern int tosh_init(void); 70 extern int i8k_init(void); 71 72 #ifdef CONFIG_PROC_FS 73 static void *misc_seq_start(struct seq_file *seq, loff_t *pos) 74 { 75 struct miscdevice *p; 76 loff_t off = 0; 77 78 down(&misc_sem); 79 list_for_each_entry(p, &misc_list, list) { 80 if (*pos == off++) 81 return p; 82 } 83 return NULL; 84 } 85 86 static void *misc_seq_next(struct seq_file *seq, void *v, loff_t *pos) 87 { 88 struct list_head *n = ((struct miscdevice *)v)->list.next; 89 90 ++*pos; 91 92 return (n != &misc_list) ? list_entry(n, struct miscdevice, list) 93 : NULL; 94 } 95 96 static void misc_seq_stop(struct seq_file *seq, void *v) 97 { 98 up(&misc_sem); 99 } 100 101 static int misc_seq_show(struct seq_file *seq, void *v) 102 { 103 const struct miscdevice *p = v; 104 105 seq_printf(seq, "%3i %s\n", p->minor, p->name ? p->name : ""); 106 return 0; 107 } 108 109 110 static struct seq_operations misc_seq_ops = { 111 .start = misc_seq_start, 112 .next = misc_seq_next, 113 .stop = misc_seq_stop, 114 .show = misc_seq_show, 115 }; 116 117 static int misc_seq_open(struct inode *inode, struct file *file) 118 { 119 return seq_open(file, &misc_seq_ops); 120 } 121 122 static struct file_operations misc_proc_fops = { 123 .owner = THIS_MODULE, 124 .open = misc_seq_open, 125 .read = seq_read, 126 .llseek = seq_lseek, 127 .release = seq_release, 128 }; 129 #endif 130 131 static int misc_open(struct inode * inode, struct file * file) 132 { 133 int minor = iminor(inode); 134 struct miscdevice *c; 135 int err = -ENODEV; 136 struct file_operations *old_fops, *new_fops = NULL; 137 138 down(&misc_sem); 139 140 list_for_each_entry(c, &misc_list, list) { 141 if (c->minor == minor) { 142 new_fops = fops_get(c->fops); 143 break; 144 } 145 } 146 147 if (!new_fops) { 148 up(&misc_sem); 149 request_module("char-major-%d-%d", MISC_MAJOR, minor); 150 down(&misc_sem); 151 152 list_for_each_entry(c, &misc_list, list) { 153 if (c->minor == minor) { 154 new_fops = fops_get(c->fops); 155 break; 156 } 157 } 158 if (!new_fops) 159 goto fail; 160 } 161 162 err = 0; 163 old_fops = file->f_op; 164 file->f_op = new_fops; 165 if (file->f_op->open) { 166 err=file->f_op->open(inode,file); 167 if (err) { 168 fops_put(file->f_op); 169 file->f_op = fops_get(old_fops); 170 } 171 } 172 fops_put(old_fops); 173 fail: 174 up(&misc_sem); 175 return err; 176 } 177 178 /* 179 * TODO for 2.7: 180 * - add a struct class_device to struct miscdevice and make all usages of 181 * them dynamic. 182 */ 183 static struct class_simple *misc_class; 184 185 static struct file_operations misc_fops = { 186 .owner = THIS_MODULE, 187 .open = misc_open, 188 }; 189 190 191 /** 192 * misc_register - register a miscellaneous device 193 * @misc: device structure 194 * 195 * Register a miscellaneous device with the kernel. If the minor 196 * number is set to %MISC_DYNAMIC_MINOR a minor number is assigned 197 * and placed in the minor field of the structure. For other cases 198 * the minor number requested is used. 199 * 200 * The structure passed is linked into the kernel and may not be 201 * destroyed until it has been unregistered. 202 * 203 * A zero is returned on success and a negative errno code for 204 * failure. 205 */ 206 207 int misc_register(struct miscdevice * misc) 208 { 209 struct miscdevice *c; 210 dev_t dev; 211 int err; 212 213 down(&misc_sem); 214 list_for_each_entry(c, &misc_list, list) { 215 if (c->minor == misc->minor) { 216 up(&misc_sem); 217 return -EBUSY; 218 } 219 } 220 221 if (misc->minor == MISC_DYNAMIC_MINOR) { 222 int i = DYNAMIC_MINORS; 223 while (--i >= 0) 224 if ( (misc_minors[i>>3] & (1 << (i&7))) == 0) 225 break; 226 if (i<0) { 227 up(&misc_sem); 228 return -EBUSY; 229 } 230 misc->minor = i; 231 } 232 233 if (misc->minor < DYNAMIC_MINORS) 234 misc_minors[misc->minor >> 3] |= 1 << (misc->minor & 7); 235 if (misc->devfs_name[0] == '\0') { 236 snprintf(misc->devfs_name, sizeof(misc->devfs_name), 237 "misc/%s", misc->name); 238 } 239 dev = MKDEV(MISC_MAJOR, misc->minor); 240 241 misc->class = class_simple_device_add(misc_class, dev, 242 misc->dev, misc->name); 243 if (IS_ERR(misc->class)) { 244 err = PTR_ERR(misc->class); 245 goto out; 246 } 247 248 err = devfs_mk_cdev(dev, S_IFCHR|S_IRUSR|S_IWUSR|S_IRGRP, 249 misc->devfs_name); 250 if (err) { 251 class_simple_device_remove(dev); 252 goto out; 253 } 254 255 /* 256 * Add it to the front, so that later devices can "override" 257 * earlier defaults 258 */ 259 list_add(&misc->list, &misc_list); 260 out: 261 up(&misc_sem); 262 return err; 263 } 264 265 /** 266 * misc_deregister - unregister a miscellaneous device 267 * @misc: device to unregister 268 * 269 * Unregister a miscellaneous device that was previously 270 * successfully registered with misc_register(). Success 271 * is indicated by a zero return, a negative errno code 272 * indicates an error. 273 */ 274 275 int misc_deregister(struct miscdevice * misc) 276 { 277 int i = misc->minor; 278 279 if (list_empty(&misc->list)) 280 return -EINVAL; 281 282 down(&misc_sem); 283 list_del(&misc->list); 284 class_simple_device_remove(MKDEV(MISC_MAJOR, misc->minor)); 285 devfs_remove(misc->devfs_name); 286 if (i < DYNAMIC_MINORS && i>0) { 287 misc_minors[i>>3] &= ~(1 << (misc->minor & 7)); 288 } 289 up(&misc_sem); 290 return 0; 291 } 292 293 EXPORT_SYMBOL(misc_register); 294 EXPORT_SYMBOL(misc_deregister); 295 296 static int __init misc_init(void) 297 { 298 #ifdef CONFIG_PROC_FS 299 struct proc_dir_entry *ent; 300 301 ent = create_proc_entry("misc", 0, NULL); 302 if (ent) 303 ent->proc_fops = &misc_proc_fops; 304 #endif 305 misc_class = class_simple_create(THIS_MODULE, "misc"); 306 if (IS_ERR(misc_class)) 307 return PTR_ERR(misc_class); 308 #ifdef CONFIG_MVME16x 309 rtc_MK48T08_init(); 310 #endif 311 #ifdef CONFIG_BVME6000 312 rtc_DP8570A_init(); 313 #endif 314 #ifdef CONFIG_PMAC_PBOOK 315 pmu_device_init(); 316 #endif 317 #ifdef CONFIG_TOSHIBA 318 tosh_init(); 319 #endif 320 #ifdef CONFIG_I8K 321 i8k_init(); 322 #endif 323 if (register_chrdev(MISC_MAJOR,"misc",&misc_fops)) { 324 printk("unable to get major %d for misc devices\n", 325 MISC_MAJOR); 326 class_simple_destroy(misc_class); 327 return -EIO; 328 } 329 return 0; 330 } 331 subsys_initcall(misc_init); 332