drivers/s390/cio/ccwgroup.c

   1 /*
   2  *  drivers/s390/cio/ccwgroup.c
   3  *  bus driver for ccwgroup
   4  *
   5  *    Copyright (C) 2002 IBM Deutschland Entwicklung GmbH,
   6  *                       IBM Corporation
   7  *    Author(s): Arnd Bergmann (arndb@de.ibm.com)
   8  *               Cornelia Huck (cornelia.huck@de.ibm.com)
   9  */
  10 #include <linux/module.h>
  11 #include <linux/errno.h>
  12 #include <linux/slab.h>
  13 #include <linux/list.h>
  14 #include <linux/device.h>
  15 #include <linux/init.h>
  16 #include <linux/ctype.h>
  17 #include <linux/dcache.h>
  18
  19 #include <asm/semaphore.h>
  20 #include <asm/ccwdev.h>
  21 #include <asm/ccwgroup.h>
  22
  23 /* In Linux 2.4, we had a channel device layer called "chandev"
  24  * that did all sorts of obscure stuff for networking devices.
  25  * This is another driver that serves as a replacement for just
  26  * one of its functions, namely the translation of single subchannels
  27  * to devices that use multiple subchannels.
  28  */
  29
  30 /* a device matches a driver if all its slave devices match the same
  31  * entry of the driver */
  32 static int
  33 ccwgroup_bus_match (struct device * dev, struct device_driver * drv)
  34 {
  35         struct ccwgroup_device *gdev;
  36         struct ccwgroup_driver *gdrv;
  37
  38         gdev = container_of(dev, struct ccwgroup_device, dev);
  39         gdrv = container_of(drv, struct ccwgroup_driver, driver);
  40
  41         if (gdev->creator_id == gdrv->driver_id)
  42                 return 1;
  43
  44         return 0;
  45 }
  46 static int
  47 ccwgroup_uevent (struct device *dev, struct kobj_uevent_env *env)
  48 {
  49         /* TODO */
  50         return 0;
  51 }
  52
  53 static struct bus_type ccwgroup_bus_type;
  54
  55 static void
  56 __ccwgroup_remove_symlinks(struct ccwgroup_device *gdev)
  57 {
  58         int i;
  59         char str[8];
  60
  61         for (i = 0; i < gdev->count; i++) {
  62                 sprintf(str, "cdev%d", i);
  63                 sysfs_remove_link(&gdev->dev.kobj, str);
  64                 sysfs_remove_link(&gdev->cdev[i]->dev.kobj, "group_device");
  65         }
  66
  67 }
  68
  69 /*
  70  * Provide an 'ungroup' attribute so the user can remove group devices no
  71  * longer needed or accidentially created. Saves memory :)
  72  */
  73 static void ccwgroup_ungroup_callback(struct device *dev)
  74 {
  75         struct ccwgroup_device *gdev = to_ccwgroupdev(dev);
  76
  77         mutex_lock(&gdev->reg_mutex);
  78         __ccwgroup_remove_symlinks(gdev);
  79         device_unregister(dev);
  80         mutex_unlock(&gdev->reg_mutex);
  81 }
  82
  83 static ssize_t
  84 ccwgroup_ungroup_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
  85 {
  86         struct ccwgroup_device *gdev;
  87         int rc;
  88
  89         gdev = to_ccwgroupdev(dev);
  90
  91         if (gdev->state != CCWGROUP_OFFLINE)
  92                 return -EINVAL;
  93
  94         /* Note that we cannot unregister the device from one of its
  95          * attribute methods, so we have to use this roundabout approach.
  96          */
  97         rc = device_schedule_callback(dev, ccwgroup_ungroup_callback);
  98         if (rc)
  99                 count = rc;
 100         return count;
 101 }
 102
 103 static DEVICE_ATTR(ungroup, 0200, NULL, ccwgroup_ungroup_store);
 104
 105 static void
 106 ccwgroup_release (struct device *dev)
 107 {
 108         struct ccwgroup_device *gdev;
 109         int i;
 110
 111         gdev = to_ccwgroupdev(dev);
 112
 113         for (i = 0; i < gdev->count; i++) {
 114                 gdev->cdev[i]->dev.driver_data = NULL;
 115                 put_device(&gdev->cdev[i]->dev);
 116         }
 117         kfree(gdev);
 118 }
 119
 120 static int
 121 __ccwgroup_create_symlinks(struct ccwgroup_device *gdev)
 122 {
 123         char str[8];
 124         int i, rc;
 125
 126         for (i = 0; i < gdev->count; i++) {
 127                 rc = sysfs_create_link(&gdev->cdev[i]->dev.kobj, &gdev->dev.kobj,
 128                                        "group_device");
 129                 if (rc) {
 130                         for (--i; i >= 0; i--)
 131                                 sysfs_remove_link(&gdev->cdev[i]->dev.kobj,
 132                                                   "group_device");
 133                         return rc;
 134                 }
 135         }
 136         for (i = 0; i < gdev->count; i++) {
 137                 sprintf(str, "cdev%d", i);
 138                 rc = sysfs_create_link(&gdev->dev.kobj, &gdev->cdev[i]->dev.kobj,
 139                                        str);
 140                 if (rc) {
 141                         for (--i; i >= 0; i--) {
 142                                 sprintf(str, "cdev%d", i);
 143                                 sysfs_remove_link(&gdev->dev.kobj, str);
 144                         }
 145                         for (i = 0; i < gdev->count; i++)
 146                                 sysfs_remove_link(&gdev->cdev[i]->dev.kobj,
 147                                                   "group_device");
 148                         return rc;
 149                 }
 150         }
 151         return 0;
 152 }
 153
 154 /**
 155  * ccwgroup_create() - create and register a ccw group device
 156  * @root: parent device for the new device
 157  * @creator_id: identifier of creating driver
 158  * @cdrv: ccw driver of slave devices
 159  * @argc: number of slave devices
 160  * @argv: bus ids of slave devices
 161  *
 162  * Create and register a new ccw group device as a child of @root. Slave
 163  * devices are obtained from the list of bus ids given in @argv[] and must all
 164  * belong to @cdrv.
 165  * Returns:
 166  *  %0 on success and an error code on failure.
 167  * Context:
 168  *  non-atomic
 169  */
 170 int ccwgroup_create(struct device *root, unsigned int creator_id,
 171                     struct ccw_driver *cdrv, int argc, char *argv[])
 172 {
 173         struct ccwgroup_device *gdev;
 174         int i;
 175         int rc;
 176
 177         if (argc > 256) /* disallow dumb users */
 178                 return -EINVAL;
 179
 180         gdev = kzalloc(sizeof(*gdev) + argc*sizeof(gdev->cdev[0]), GFP_KERNEL);
 181         if (!gdev)
 182                 return -ENOMEM;
 183
 184         atomic_set(&gdev->onoff, 0);
 185         mutex_init(&gdev->reg_mutex);
 186         mutex_lock(&gdev->reg_mutex);
 187         for (i = 0; i < argc; i++) {
 188                 gdev->cdev[i] = get_ccwdev_by_busid(cdrv, argv[i]);
 189
 190                 /* all devices have to be of the same type in
 191                  * order to be grouped */
 192                 if (!gdev->cdev[i]
 193                     || gdev->cdev[i]->id.driver_info !=
 194                     gdev->cdev[0]->id.driver_info) {
 195                         rc = -EINVAL;
 196                         goto error;
 197                 }
 198                 /* Don't allow a device to belong to more than one group. */
 199                 if (gdev->cdev[i]->dev.driver_data) {
 200                         rc = -EINVAL;
 201                         goto error;
 202                 }
 203                 gdev->cdev[i]->dev.driver_data = gdev;
 204         }
 205
 206         gdev->creator_id = creator_id;
 207         gdev->count = argc;
 208         gdev->dev.bus = &ccwgroup_bus_type;
 209         gdev->dev.parent = root;
 210         gdev->dev.release = ccwgroup_release;
 211
 212         snprintf (gdev->dev.bus_id, BUS_ID_SIZE, "%s",
 213                         gdev->cdev[0]->dev.bus_id);
 214
 215         rc = device_register(&gdev->dev);
 216         if (rc)
 217                 goto error;
 218         get_device(&gdev->dev);
 219         rc = device_create_file(&gdev->dev, &dev_attr_ungroup);
 220
 221         if (rc) {
 222                 device_unregister(&gdev->dev);
 223                 goto error;
 224         }
 225
 226         rc = __ccwgroup_create_symlinks(gdev);
 227         if (!rc) {
 228                 mutex_unlock(&gdev->reg_mutex);
 229                 put_device(&gdev->dev);
 230                 return 0;
 231         }
 232         device_remove_file(&gdev->dev, &dev_attr_ungroup);
 233         device_unregister(&gdev->dev);
 234 error:
 235         for (i = 0; i < argc; i++)
 236                 if (gdev->cdev[i]) {
 237                         if (gdev->cdev[i]->dev.driver_data == gdev)
 238                                 gdev->cdev[i]->dev.driver_data = NULL;
 239                         put_device(&gdev->cdev[i]->dev);
 240                 }
 241         mutex_unlock(&gdev->reg_mutex);
 242         put_device(&gdev->dev);
 243         return rc;
 244 }
 245
 246 static int __init
 247 init_ccwgroup (void)
 248 {
 249         return bus_register (&ccwgroup_bus_type);
 250 }
 251
 252 static void __exit
 253 cleanup_ccwgroup (void)
 254 {
 255         bus_unregister (&ccwgroup_bus_type);
 256 }
 257
 258 module_init(init_ccwgroup);
 259 module_exit(cleanup_ccwgroup);
 260
 261 /************************** driver stuff ******************************/
 262
 263 static int
 264 ccwgroup_set_online(struct ccwgroup_device *gdev)
 265 {
 266         struct ccwgroup_driver *gdrv;
 267         int ret;
 268
 269         if (atomic_cmpxchg(&gdev->onoff, 0, 1) != 0)
 270                 return -EAGAIN;
 271         if (gdev->state == CCWGROUP_ONLINE) {
 272                 ret = 0;
 273                 goto out;
 274         }
 275         if (!gdev->dev.driver) {
 276                 ret = -EINVAL;
 277                 goto out;
 278         }
 279         gdrv = to_ccwgroupdrv (gdev->dev.driver);
 280         if ((ret = gdrv->set_online ? gdrv->set_online(gdev) : 0))
 281                 goto out;
 282
 283         gdev->state = CCWGROUP_ONLINE;
 284  out:
 285         atomic_set(&gdev->onoff, 0);
 286         return ret;
 287 }
 288
 289 static int
 290 ccwgroup_set_offline(struct ccwgroup_device *gdev)
 291 {
 292         struct ccwgroup_driver *gdrv;
 293         int ret;
 294
 295         if (atomic_cmpxchg(&gdev->onoff, 0, 1) != 0)
 296                 return -EAGAIN;
 297         if (gdev->state == CCWGROUP_OFFLINE) {
 298                 ret = 0;
 299                 goto out;
 300         }
 301         if (!gdev->dev.driver) {
 302                 ret = -EINVAL;
 303                 goto out;
 304         }
 305         gdrv = to_ccwgroupdrv (gdev->dev.driver);
 306         if ((ret = gdrv->set_offline ? gdrv->set_offline(gdev) : 0))
 307                 goto out;
 308
 309         gdev->state = CCWGROUP_OFFLINE;
 310  out:
 311         atomic_set(&gdev->onoff, 0);
 312         return ret;
 313 }
 314
 315 static ssize_t
 316 ccwgroup_online_store (struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
 317 {
 318         struct ccwgroup_device *gdev;
 319         struct ccwgroup_driver *gdrv;
 320         unsigned int value;
 321         int ret;
 322
 323         gdev = to_ccwgroupdev(dev);
 324         if (!dev->driver)
 325                 return count;
 326
 327         gdrv = to_ccwgroupdrv (gdev->dev.driver);
 328         if (!try_module_get(gdrv->owner))
 329                 return -EINVAL;
 330
 331         value = simple_strtoul(buf, NULL, 0);
 332         ret = count;
 333         if (value == 1)
 334                 ccwgroup_set_online(gdev);
 335         else if (value == 0)
 336                 ccwgroup_set_offline(gdev);
 337         else
 338                 ret = -EINVAL;
 339         module_put(gdrv->owner);
 340         return ret;
 341 }
 342
 343 static ssize_t
 344 ccwgroup_online_show (struct device *dev, struct device_attribute *attr, char *buf)
 345 {
 346         int online;
 347
 348         online = (to_ccwgroupdev(dev)->state == CCWGROUP_ONLINE);
 349
 350         return sprintf(buf, online ? "1\n" : "0\n");
 351 }
 352
 353 static DEVICE_ATTR(online, 0644, ccwgroup_online_show, ccwgroup_online_store);
 354
 355 static int
 356 ccwgroup_probe (struct device *dev)
 357 {
 358         struct ccwgroup_device *gdev;
 359         struct ccwgroup_driver *gdrv;
 360
 361         int ret;
 362
 363         gdev = to_ccwgroupdev(dev);
 364         gdrv = to_ccwgroupdrv(dev->driver);
 365
 366         if ((ret = device_create_file(dev, &dev_attr_online)))
 367                 return ret;
 368
 369         ret = gdrv->probe ? gdrv->probe(gdev) : -ENODEV;
 370         if (ret)
 371                 device_remove_file(dev, &dev_attr_online);
 372
 373         return ret;
 374 }
 375
 376 static int
 377 ccwgroup_remove (struct device *dev)
 378 {
 379         struct ccwgroup_device *gdev;
 380         struct ccwgroup_driver *gdrv;
 381
 382         gdev = to_ccwgroupdev(dev);
 383         gdrv = to_ccwgroupdrv(dev->driver);
 384
 385         device_remove_file(dev, &dev_attr_online);
 386
 387         if (gdrv && gdrv->remove)
 388                 gdrv->remove(gdev);
 389         return 0;
 390 }
 391
 392 static struct bus_type ccwgroup_bus_type = {
 393         .name   = "ccwgroup",
 394         .match  = ccwgroup_bus_match,
 395         .uevent = ccwgroup_uevent,
 396         .probe  = ccwgroup_probe,
 397         .remove = ccwgroup_remove,
 398 };
 399
 400 /**
 401  * ccwgroup_driver_register() - register a ccw group driver
 402  * @cdriver: driver to be registered
 403  *
 404  * This function is mainly a wrapper around driver_register().
 405  */
 406 int ccwgroup_driver_register(struct ccwgroup_driver *cdriver)
 407 {
 408         /* register our new driver with the core */
 409         cdriver->driver.bus = &ccwgroup_bus_type;
 410         cdriver->driver.name = cdriver->name;
 411
 412         return driver_register(&cdriver->driver);
 413 }
 414
 415 static int
 416 __ccwgroup_match_all(struct device *dev, void *data)
 417 {
 418         return 1;
 419 }
 420
 421 /**
 422  * ccwgroup_driver_unregister() - deregister a ccw group driver
 423  * @cdriver: driver to be deregistered
 424  *
 425  * This function is mainly a wrapper around driver_unregister().
 426  */
 427 void ccwgroup_driver_unregister(struct ccwgroup_driver *cdriver)
 428 {
 429         struct device *dev;
 430
 431         /* We don't want ccwgroup devices to live longer than their driver. */
 432         get_driver(&cdriver->driver);
 433         while ((dev = driver_find_device(&cdriver->driver, NULL, NULL,
 434                                          __ccwgroup_match_all))) {
 435                 struct ccwgroup_device *gdev = to_ccwgroupdev(dev);
 436
 437                 mutex_lock(&gdev->reg_mutex);
 438                 __ccwgroup_remove_symlinks(gdev);
 439                 device_unregister(dev);
 440                 mutex_unlock(&gdev->reg_mutex);
 441                 put_device(dev);
 442         }
 443         put_driver(&cdriver->driver);
 444         driver_unregister(&cdriver->driver);
 445 }
 446
 447 /**
 448  * ccwgroup_probe_ccwdev() - probe function for slave devices
 449  * @cdev: ccw device to be probed
 450  *
 451  * This is a dummy probe function for ccw devices that are slave devices in
 452  * a ccw group device.
 453  * Returns:
 454  *  always %0
 455  */
 456 int ccwgroup_probe_ccwdev(struct ccw_device *cdev)
 457 {
 458         return 0;
 459 }
 460
 461 static struct ccwgroup_device *
 462 __ccwgroup_get_gdev_by_cdev(struct ccw_device *cdev)
 463 {
 464         struct ccwgroup_device *gdev;
 465
 466         if (cdev->dev.driver_data) {
 467                 gdev = (struct ccwgroup_device *)cdev->dev.driver_data;
 468                 if (get_device(&gdev->dev)) {
 469                         mutex_lock(&gdev->reg_mutex);
 470                         if (device_is_registered(&gdev->dev))
 471                                 return gdev;
 472                         mutex_unlock(&gdev->reg_mutex);
 473                         put_device(&gdev->dev);
 474                 }
 475                 return NULL;
 476         }
 477         return NULL;
 478 }
 479
 480 /**
 481  * ccwgroup_remove_ccwdev() - remove function for slave devices
 482  * @cdev: ccw device to be removed
 483  *
 484  * This is a remove function for ccw devices that are slave devices in a ccw
 485  * group device. It sets the ccw device offline and also deregisters the
 486  * embedding ccw group device.
 487  */
 488 void ccwgroup_remove_ccwdev(struct ccw_device *cdev)
 489 {
 490         struct ccwgroup_device *gdev;
 491
 492         /* Ignore offlining errors, device is gone anyway. */
 493         ccw_device_set_offline(cdev);
 494         /* If one of its devices is gone, the whole group is done for. */
 495         gdev = __ccwgroup_get_gdev_by_cdev(cdev);
 496         if (gdev) {
 497                 __ccwgroup_remove_symlinks(gdev);
 498                 device_unregister(&gdev->dev);
 499                 mutex_unlock(&gdev->reg_mutex);
 500                 put_device(&gdev->dev);
 501         }
 502 }
 503
 504 MODULE_LICENSE("GPL");
 505 EXPORT_SYMBOL(ccwgroup_driver_register);
 506 EXPORT_SYMBOL(ccwgroup_driver_unregister);
 507 EXPORT_SYMBOL(ccwgroup_create);
 508 EXPORT_SYMBOL(ccwgroup_probe_ccwdev);
 509 EXPORT_SYMBOL(ccwgroup_remove_ccwdev);