drivers/s390/cio/ccwgroup.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  bus driver for ccwgroup
   4  *
   5  *  Copyright IBM Corp. 2002, 2012
   6  *
   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/cio.h>
  20 #include <asm/ccwdev.h>
  21 #include <asm/ccwgroup.h>
  22
  23 #include "device.h"
  24
  25 #define CCW_BUS_ID_SIZE         10
  26
  27 /* In Linux 2.4, we had a channel device layer called "chandev"
  28  * that did all sorts of obscure stuff for networking devices.
  29  * This is another driver that serves as a replacement for just
  30  * one of its functions, namely the translation of single subchannels
  31  * to devices that use multiple subchannels.
  32  */
  33
  34 static struct bus_type ccwgroup_bus_type;
  35
  36 static void __ccwgroup_remove_symlinks(struct ccwgroup_device *gdev)
  37 {
  38         int i;
  39         char str[16];
  40
  41         for (i = 0; i < gdev->count; i++) {
  42                 sprintf(str, "cdev%d", i);
  43                 sysfs_remove_link(&gdev->dev.kobj, str);
  44                 sysfs_remove_link(&gdev->cdev[i]->dev.kobj, "group_device");
  45         }
  46 }
  47
  48 /*
  49  * Remove references from ccw devices to ccw group device and from
  50  * ccw group device to ccw devices.
  51  */
  52 static void __ccwgroup_remove_cdev_refs(struct ccwgroup_device *gdev)
  53 {
  54         struct ccw_device *cdev;
  55         int i;
  56
  57         for (i = 0; i < gdev->count; i++) {
  58                 cdev = gdev->cdev[i];
  59                 if (!cdev)
  60                         continue;
  61                 spin_lock_irq(cdev->ccwlock);
  62                 dev_set_drvdata(&cdev->dev, NULL);
  63                 spin_unlock_irq(cdev->ccwlock);
  64                 gdev->cdev[i] = NULL;
  65                 put_device(&cdev->dev);
  66         }
  67 }
  68
  69 /**
  70  * ccwgroup_set_online() - enable a ccwgroup device
  71  * @gdev: target ccwgroup device
  72  *
  73  * This function attempts to put the ccwgroup device into the online state.
  74  * Returns:
  75  *  %0 on success and a negative error value on failure.
  76  */
  77 int ccwgroup_set_online(struct ccwgroup_device *gdev)
  78 {
  79         struct ccwgroup_driver *gdrv = to_ccwgroupdrv(gdev->dev.driver);
  80         int ret = -EINVAL;
  81
  82         if (atomic_cmpxchg(&gdev->onoff, 0, 1) != 0)
  83                 return -EAGAIN;
  84         if (gdev->state == CCWGROUP_ONLINE)
  85                 goto out;
  86         if (gdrv->set_online)
  87                 ret = gdrv->set_online(gdev);
  88         if (ret)
  89                 goto out;
  90
  91         gdev->state = CCWGROUP_ONLINE;
  92 out:
  93         atomic_set(&gdev->onoff, 0);
  94         return ret;
  95 }
  96 EXPORT_SYMBOL(ccwgroup_set_online);
  97
  98 /**
  99  * ccwgroup_set_offline() - disable a ccwgroup device
 100  * @gdev: target ccwgroup device
 101  *
 102  * This function attempts to put the ccwgroup device into the offline state.
 103  * Returns:
 104  *  %0 on success and a negative error value on failure.
 105  */
 106 int ccwgroup_set_offline(struct ccwgroup_device *gdev)
 107 {
 108         struct ccwgroup_driver *gdrv = to_ccwgroupdrv(gdev->dev.driver);
 109         int ret = -EINVAL;
 110
 111         if (atomic_cmpxchg(&gdev->onoff, 0, 1) != 0)
 112                 return -EAGAIN;
 113         if (gdev->state == CCWGROUP_OFFLINE)
 114                 goto out;
 115         if (gdrv->set_offline)
 116                 ret = gdrv->set_offline(gdev);
 117         if (ret)
 118                 goto out;
 119
 120         gdev->state = CCWGROUP_OFFLINE;
 121 out:
 122         atomic_set(&gdev->onoff, 0);
 123         return ret;
 124 }
 125 EXPORT_SYMBOL(ccwgroup_set_offline);
 126
 127 static ssize_t ccwgroup_online_store(struct device *dev,
 128                                      struct device_attribute *attr,
 129                                      const char *buf, size_t count)
 130 {
 131         struct ccwgroup_device *gdev = to_ccwgroupdev(dev);
 132         unsigned long value;
 133         int ret;
 134
 135         device_lock(dev);
 136         if (!dev->driver) {
 137                 ret = -EINVAL;
 138                 goto out;
 139         }
 140
 141         ret = kstrtoul(buf, 0, &value);
 142         if (ret)
 143                 goto out;
 144
 145         if (value == 1)
 146                 ret = ccwgroup_set_online(gdev);
 147         else if (value == 0)
 148                 ret = ccwgroup_set_offline(gdev);
 149         else
 150                 ret = -EINVAL;
 151 out:
 152         device_unlock(dev);
 153         return (ret == 0) ? count : ret;
 154 }
 155
 156 static ssize_t ccwgroup_online_show(struct device *dev,
 157                                     struct device_attribute *attr,
 158                                     char *buf)
 159 {
 160         struct ccwgroup_device *gdev = to_ccwgroupdev(dev);
 161         int online;
 162
 163         online = (gdev->state == CCWGROUP_ONLINE) ? 1 : 0;
 164
 165         return scnprintf(buf, PAGE_SIZE, "%d\n", online);
 166 }
 167
 168 /*
 169  * Provide an 'ungroup' attribute so the user can remove group devices no
 170  * longer needed or accidentially created. Saves memory :)
 171  */
 172 static void ccwgroup_ungroup(struct ccwgroup_device *gdev)
 173 {
 174         mutex_lock(&gdev->reg_mutex);
 175         if (device_is_registered(&gdev->dev)) {
 176                 __ccwgroup_remove_symlinks(gdev);
 177                 device_unregister(&gdev->dev);
 178                 __ccwgroup_remove_cdev_refs(gdev);
 179         }
 180         mutex_unlock(&gdev->reg_mutex);
 181 }
 182
 183 static ssize_t ccwgroup_ungroup_store(struct device *dev,
 184                                       struct device_attribute *attr,
 185                                       const char *buf, size_t count)
 186 {
 187         struct ccwgroup_device *gdev = to_ccwgroupdev(dev);
 188         int rc = 0;
 189
 190         /* Prevent concurrent online/offline processing and ungrouping. */
 191         if (atomic_cmpxchg(&gdev->onoff, 0, 1) != 0)
 192                 return -EAGAIN;
 193         if (gdev->state != CCWGROUP_OFFLINE) {
 194                 rc = -EINVAL;
 195                 goto out;
 196         }
 197
 198         if (device_remove_file_self(dev, attr))
 199                 ccwgroup_ungroup(gdev);
 200         else
 201                 rc = -ENODEV;
 202 out:
 203         if (rc) {
 204                 /* Release onoff "lock" when ungrouping failed. */
 205                 atomic_set(&gdev->onoff, 0);
 206                 return rc;
 207         }
 208         return count;
 209 }
 210 static DEVICE_ATTR(ungroup, 0200, NULL, ccwgroup_ungroup_store);
 211 static DEVICE_ATTR(online, 0644, ccwgroup_online_show, ccwgroup_online_store);
 212
 213 static struct attribute *ccwgroup_dev_attrs[] = {
 214         &dev_attr_online.attr,
 215         &dev_attr_ungroup.attr,
 216         NULL,
 217 };
 218 ATTRIBUTE_GROUPS(ccwgroup_dev);
 219
 220 static void ccwgroup_ungroup_workfn(struct work_struct *work)
 221 {
 222         struct ccwgroup_device *gdev =
 223                 container_of(work, struct ccwgroup_device, ungroup_work);
 224
 225         ccwgroup_ungroup(gdev);
 226         put_device(&gdev->dev);
 227 }
 228
 229 static void ccwgroup_release(struct device *dev)
 230 {
 231         kfree(to_ccwgroupdev(dev));
 232 }
 233
 234 static int __ccwgroup_create_symlinks(struct ccwgroup_device *gdev)
 235 {
 236         char str[16];
 237         int i, rc;
 238
 239         for (i = 0; i < gdev->count; i++) {
 240                 rc = sysfs_create_link(&gdev->cdev[i]->dev.kobj,
 241                                        &gdev->dev.kobj, "group_device");
 242                 if (rc) {
 243                         for (--i; i >= 0; i--)
 244                                 sysfs_remove_link(&gdev->cdev[i]->dev.kobj,
 245                                                   "group_device");
 246                         return rc;
 247                 }
 248         }
 249         for (i = 0; i < gdev->count; i++) {
 250                 sprintf(str, "cdev%d", i);
 251                 rc = sysfs_create_link(&gdev->dev.kobj,
 252                                        &gdev->cdev[i]->dev.kobj, str);
 253                 if (rc) {
 254                         for (--i; i >= 0; i--) {
 255                                 sprintf(str, "cdev%d", i);
 256                                 sysfs_remove_link(&gdev->dev.kobj, str);
 257                         }
 258                         for (i = 0; i < gdev->count; i++)
 259                                 sysfs_remove_link(&gdev->cdev[i]->dev.kobj,
 260                                                   "group_device");
 261                         return rc;
 262                 }
 263         }
 264         return 0;
 265 }
 266
 267 static int __get_next_id(const char **buf, struct ccw_dev_id *id)
 268 {
 269         unsigned int cssid, ssid, devno;
 270         int ret = 0, len;
 271         char *start, *end;
 272
 273         start = (char *)*buf;
 274         end = strchr(start, ',');
 275         if (!end) {
 276                 /* Last entry. Strip trailing newline, if applicable. */
 277                 end = strchr(start, '\n');
 278                 if (end)
 279                         *end = '\0';
 280                 len = strlen(start) + 1;
 281         } else {
 282                 len = end - start + 1;
 283                 end++;
 284         }
 285         if (len <= CCW_BUS_ID_SIZE) {
 286                 if (sscanf(start, "%2x.%1x.%04x", &cssid, &ssid, &devno) != 3)
 287                         ret = -EINVAL;
 288         } else
 289                 ret = -EINVAL;
 290
 291         if (!ret) {
 292                 id->ssid = ssid;
 293                 id->devno = devno;
 294         }
 295         *buf = end;
 296         return ret;
 297 }
 298
 299 /**
 300  * ccwgroup_create_dev() - create and register a ccw group device
 301  * @parent: parent device for the new device
 302  * @gdrv: driver for the new group device
 303  * @num_devices: number of slave devices
 304  * @buf: buffer containing comma separated bus ids of slave devices
 305  *
 306  * Create and register a new ccw group device as a child of @parent. Slave
 307  * devices are obtained from the list of bus ids given in @buf.
 308  * Returns:
 309  *  %0 on success and an error code on failure.
 310  * Context:
 311  *  non-atomic
 312  */
 313 int ccwgroup_create_dev(struct device *parent, struct ccwgroup_driver *gdrv,
 314                         int num_devices, const char *buf)
 315 {
 316         struct ccwgroup_device *gdev;
 317         struct ccw_dev_id dev_id;
 318         int rc, i;
 319
 320         if (num_devices < 1)
 321                 return -EINVAL;
 322
 323         gdev = kzalloc(struct_size(gdev, cdev, num_devices), GFP_KERNEL);
 324         if (!gdev)
 325                 return -ENOMEM;
 326
 327         atomic_set(&gdev->onoff, 0);
 328         mutex_init(&gdev->reg_mutex);
 329         mutex_lock(&gdev->reg_mutex);
 330         INIT_WORK(&gdev->ungroup_work, ccwgroup_ungroup_workfn);
 331         gdev->count = num_devices;
 332         gdev->dev.bus = &ccwgroup_bus_type;
 333         gdev->dev.parent = parent;
 334         gdev->dev.release = ccwgroup_release;
 335         device_initialize(&gdev->dev);
 336
 337         for (i = 0; i < num_devices && buf; i++) {
 338                 rc = __get_next_id(&buf, &dev_id);
 339                 if (rc != 0)
 340                         goto error;
 341                 gdev->cdev[i] = get_ccwdev_by_dev_id(&dev_id);
 342                 /*
 343                  * All devices have to be of the same type in
 344                  * order to be grouped.
 345                  */
 346                 if (!gdev->cdev[i] || !gdev->cdev[i]->drv ||
 347                     gdev->cdev[i]->drv != gdev->cdev[0]->drv ||
 348                     gdev->cdev[i]->id.driver_info !=
 349                     gdev->cdev[0]->id.driver_info) {
 350                         rc = -EINVAL;
 351                         goto error;
 352                 }
 353                 /* Don't allow a device to belong to more than one group. */
 354                 spin_lock_irq(gdev->cdev[i]->ccwlock);
 355                 if (dev_get_drvdata(&gdev->cdev[i]->dev)) {
 356                         spin_unlock_irq(gdev->cdev[i]->ccwlock);
 357                         rc = -EINVAL;
 358                         goto error;
 359                 }
 360                 dev_set_drvdata(&gdev->cdev[i]->dev, gdev);
 361                 spin_unlock_irq(gdev->cdev[i]->ccwlock);
 362         }
 363         /* Check for sufficient number of bus ids. */
 364         if (i < num_devices) {
 365                 rc = -EINVAL;
 366                 goto error;
 367         }
 368         /* Check for trailing stuff. */
 369         if (i == num_devices && buf && strlen(buf) > 0) {
 370                 rc = -EINVAL;
 371                 goto error;
 372         }
 373         /* Check if the devices are bound to the required ccw driver. */
 374         if (gdrv && gdrv->ccw_driver &&
 375             gdev->cdev[0]->drv != gdrv->ccw_driver) {
 376                 rc = -EINVAL;
 377                 goto error;
 378         }
 379
 380         dev_set_name(&gdev->dev, "%s", dev_name(&gdev->cdev[0]->dev));
 381
 382         if (gdrv) {
 383                 gdev->dev.driver = &gdrv->driver;
 384                 rc = gdrv->setup ? gdrv->setup(gdev) : 0;
 385                 if (rc)
 386                         goto error;
 387         }
 388         rc = device_add(&gdev->dev);
 389         if (rc)
 390                 goto error;
 391         rc = __ccwgroup_create_symlinks(gdev);
 392         if (rc) {
 393                 device_del(&gdev->dev);
 394                 goto error;
 395         }
 396         mutex_unlock(&gdev->reg_mutex);
 397         return 0;
 398 error:
 399         for (i = 0; i < num_devices; i++)
 400                 if (gdev->cdev[i]) {
 401                         spin_lock_irq(gdev->cdev[i]->ccwlock);
 402                         if (dev_get_drvdata(&gdev->cdev[i]->dev) == gdev)
 403                                 dev_set_drvdata(&gdev->cdev[i]->dev, NULL);
 404                         spin_unlock_irq(gdev->cdev[i]->ccwlock);
 405                         put_device(&gdev->cdev[i]->dev);
 406                         gdev->cdev[i] = NULL;
 407                 }
 408         mutex_unlock(&gdev->reg_mutex);
 409         put_device(&gdev->dev);
 410         return rc;
 411 }
 412 EXPORT_SYMBOL(ccwgroup_create_dev);
 413
 414 static int ccwgroup_notifier(struct notifier_block *nb, unsigned long action,
 415                              void *data)
 416 {
 417         struct ccwgroup_device *gdev = to_ccwgroupdev(data);
 418
 419         if (action == BUS_NOTIFY_UNBIND_DRIVER) {
 420                 get_device(&gdev->dev);
 421                 schedule_work(&gdev->ungroup_work);
 422         }
 423
 424         return NOTIFY_OK;
 425 }
 426
 427 static struct notifier_block ccwgroup_nb = {
 428         .notifier_call = ccwgroup_notifier
 429 };
 430
 431 static int __init init_ccwgroup(void)
 432 {
 433         int ret;
 434
 435         ret = bus_register(&ccwgroup_bus_type);
 436         if (ret)
 437                 return ret;
 438
 439         ret = bus_register_notifier(&ccwgroup_bus_type, &ccwgroup_nb);
 440         if (ret)
 441                 bus_unregister(&ccwgroup_bus_type);
 442
 443         return ret;
 444 }
 445
 446 static void __exit cleanup_ccwgroup(void)
 447 {
 448         bus_unregister_notifier(&ccwgroup_bus_type, &ccwgroup_nb);
 449         bus_unregister(&ccwgroup_bus_type);
 450 }
 451
 452 module_init(init_ccwgroup);
 453 module_exit(cleanup_ccwgroup);
 454
 455 /************************** driver stuff ******************************/
 456
 457 static int ccwgroup_remove(struct device *dev)
 458 {
 459         struct ccwgroup_device *gdev = to_ccwgroupdev(dev);
 460         struct ccwgroup_driver *gdrv = to_ccwgroupdrv(dev->driver);
 461
 462         if (!dev->driver)
 463                 return 0;
 464         if (gdrv->remove)
 465                 gdrv->remove(gdev);
 466
 467         return 0;
 468 }
 469
 470 static void ccwgroup_shutdown(struct device *dev)
 471 {
 472         struct ccwgroup_device *gdev = to_ccwgroupdev(dev);
 473         struct ccwgroup_driver *gdrv = to_ccwgroupdrv(dev->driver);
 474
 475         if (!dev->driver)
 476                 return;
 477         if (gdrv->shutdown)
 478                 gdrv->shutdown(gdev);
 479 }
 480
 481 static struct bus_type ccwgroup_bus_type = {
 482         .name   = "ccwgroup",
 483         .dev_groups = ccwgroup_dev_groups,
 484         .remove = ccwgroup_remove,
 485         .shutdown = ccwgroup_shutdown,
 486 };
 487
 488 bool dev_is_ccwgroup(struct device *dev)
 489 {
 490         return dev->bus == &ccwgroup_bus_type;
 491 }
 492 EXPORT_SYMBOL(dev_is_ccwgroup);
 493
 494 /**
 495  * ccwgroup_driver_register() - register a ccw group driver
 496  * @cdriver: driver to be registered
 497  *
 498  * This function is mainly a wrapper around driver_register().
 499  */
 500 int ccwgroup_driver_register(struct ccwgroup_driver *cdriver)
 501 {
 502         /* register our new driver with the core */
 503         cdriver->driver.bus = &ccwgroup_bus_type;
 504
 505         return driver_register(&cdriver->driver);
 506 }
 507 EXPORT_SYMBOL(ccwgroup_driver_register);
 508
 509 /**
 510  * ccwgroup_driver_unregister() - deregister a ccw group driver
 511  * @cdriver: driver to be deregistered
 512  *
 513  * This function is mainly a wrapper around driver_unregister().
 514  */
 515 void ccwgroup_driver_unregister(struct ccwgroup_driver *cdriver)
 516 {
 517         struct device *dev;
 518
 519         /* We don't want ccwgroup devices to live longer than their driver. */
 520         while ((dev = driver_find_next_device(&cdriver->driver, NULL))) {
 521                 struct ccwgroup_device *gdev = to_ccwgroupdev(dev);
 522
 523                 ccwgroup_ungroup(gdev);
 524                 put_device(dev);
 525         }
 526         driver_unregister(&cdriver->driver);
 527 }
 528 EXPORT_SYMBOL(ccwgroup_driver_unregister);
 529
 530 /**
 531  * get_ccwgroupdev_by_busid() - obtain device from a bus id
 532  * @gdrv: driver the device is owned by
 533  * @bus_id: bus id of the device to be searched
 534  *
 535  * This function searches all devices owned by @gdrv for a device with a bus
 536  * id matching @bus_id.
 537  * Returns:
 538  *  If a match is found, its reference count of the found device is increased
 539  *  and it is returned; else %NULL is returned.
 540  */
 541 struct ccwgroup_device *get_ccwgroupdev_by_busid(struct ccwgroup_driver *gdrv,
 542                                                  char *bus_id)
 543 {
 544         struct device *dev;
 545
 546         dev = driver_find_device_by_name(&gdrv->driver, bus_id);
 547
 548         return dev ? to_ccwgroupdev(dev) : NULL;
 549 }
 550 EXPORT_SYMBOL_GPL(get_ccwgroupdev_by_busid);
 551
 552 /**
 553  * ccwgroup_probe_ccwdev() - probe function for slave devices
 554  * @cdev: ccw device to be probed
 555  *
 556  * This is a dummy probe function for ccw devices that are slave devices in
 557  * a ccw group device.
 558  * Returns:
 559  *  always %0
 560  */
 561 int ccwgroup_probe_ccwdev(struct ccw_device *cdev)
 562 {
 563         return 0;
 564 }
 565 EXPORT_SYMBOL(ccwgroup_probe_ccwdev);
 566
 567 /**
 568  * ccwgroup_remove_ccwdev() - remove function for slave devices
 569  * @cdev: ccw device to be removed
 570  *
 571  * This is a remove function for ccw devices that are slave devices in a ccw
 572  * group device. It sets the ccw device offline and also deregisters the
 573  * embedding ccw group device.
 574  */
 575 void ccwgroup_remove_ccwdev(struct ccw_device *cdev)
 576 {
 577         struct ccwgroup_device *gdev;
 578
 579         /* Ignore offlining errors, device is gone anyway. */
 580         ccw_device_set_offline(cdev);
 581         /* If one of its devices is gone, the whole group is done for. */
 582         spin_lock_irq(cdev->ccwlock);
 583         gdev = dev_get_drvdata(&cdev->dev);
 584         if (!gdev) {
 585                 spin_unlock_irq(cdev->ccwlock);
 586                 return;
 587         }
 588         /* Get ccwgroup device reference for local processing. */
 589         get_device(&gdev->dev);
 590         spin_unlock_irq(cdev->ccwlock);
 591         /* Unregister group device. */
 592         ccwgroup_ungroup(gdev);
 593         /* Release ccwgroup device reference for local processing. */
 594         put_device(&gdev->dev);
 595 }
 596 EXPORT_SYMBOL(ccwgroup_remove_ccwdev);
 597 MODULE_LICENSE("GPL");