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 const 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  * ccwgroup_set_online() - enable a ccwgroup device
  50  * @gdev: target ccwgroup device
  51  *
  52  * This function attempts to put the ccwgroup device into the online state.
  53  * Returns:
  54  *  %0 on success and a negative error value on failure.
  55  */
  56 int ccwgroup_set_online(struct ccwgroup_device *gdev)
  57 {
  58         struct ccwgroup_driver *gdrv = to_ccwgroupdrv(gdev->dev.driver);
  59         int ret = -EINVAL;
  60
  61         if (atomic_cmpxchg(&gdev->onoff, 0, 1) != 0)
  62                 return -EAGAIN;
  63         if (gdev->state == CCWGROUP_ONLINE)
  64                 goto out;
  65         if (gdrv->set_online)
  66                 ret = gdrv->set_online(gdev);
  67         if (ret)
  68                 goto out;
  69
  70         gdev->state = CCWGROUP_ONLINE;
  71 out:
  72         atomic_set(&gdev->onoff, 0);
  73         return ret;
  74 }
  75 EXPORT_SYMBOL(ccwgroup_set_online);
  76
  77 /**
  78  * ccwgroup_set_offline() - disable a ccwgroup device
  79  * @gdev: target ccwgroup device
  80  * @call_gdrv: Call the registered gdrv set_offline function
  81  *
  82  * This function attempts to put the ccwgroup device into the offline state.
  83  * Returns:
  84  *  %0 on success and a negative error value on failure.
  85  */
  86 int ccwgroup_set_offline(struct ccwgroup_device *gdev, bool call_gdrv)
  87 {
  88         struct ccwgroup_driver *gdrv = to_ccwgroupdrv(gdev->dev.driver);
  89         int ret = -EINVAL;
  90
  91         if (atomic_cmpxchg(&gdev->onoff, 0, 1) != 0)
  92                 return -EAGAIN;
  93         if (gdev->state == CCWGROUP_OFFLINE)
  94                 goto out;
  95         if (!call_gdrv) {
  96                 ret = 0;
  97                 goto offline;
  98         }
  99         if (gdrv->set_offline)
 100                 ret = gdrv->set_offline(gdev);
 101         if (ret)
 102                 goto out;
 103
 104 offline:
 105         gdev->state = CCWGROUP_OFFLINE;
 106 out:
 107         atomic_set(&gdev->onoff, 0);
 108         return ret;
 109 }
 110 EXPORT_SYMBOL(ccwgroup_set_offline);
 111
 112 static ssize_t ccwgroup_online_store(struct device *dev,
 113                                      struct device_attribute *attr,
 114                                      const char *buf, size_t count)
 115 {
 116         struct ccwgroup_device *gdev = to_ccwgroupdev(dev);
 117         unsigned long value;
 118         int ret;
 119
 120         device_lock(dev);
 121         if (!dev->driver) {
 122                 ret = -EINVAL;
 123                 goto out;
 124         }
 125
 126         ret = kstrtoul(buf, 0, &value);
 127         if (ret)
 128                 goto out;
 129
 130         if (value == 1)
 131                 ret = ccwgroup_set_online(gdev);
 132         else if (value == 0)
 133                 ret = ccwgroup_set_offline(gdev, true);
 134         else
 135                 ret = -EINVAL;
 136 out:
 137         device_unlock(dev);
 138         return (ret == 0) ? count : ret;
 139 }
 140
 141 static ssize_t ccwgroup_online_show(struct device *dev,
 142                                     struct device_attribute *attr,
 143                                     char *buf)
 144 {
 145         struct ccwgroup_device *gdev = to_ccwgroupdev(dev);
 146         int online;
 147
 148         online = (gdev->state == CCWGROUP_ONLINE) ? 1 : 0;
 149
 150         return sysfs_emit(buf, "%d\n", online);
 151 }
 152
 153 /*
 154  * Provide an 'ungroup' attribute so the user can remove group devices no
 155  * longer needed or accidentally created. Saves memory :)
 156  */
 157 static void ccwgroup_ungroup(struct ccwgroup_device *gdev)
 158 {
 159         mutex_lock(&gdev->reg_mutex);
 160         if (device_is_registered(&gdev->dev)) {
 161                 __ccwgroup_remove_symlinks(gdev);
 162                 device_unregister(&gdev->dev);
 163         }
 164         mutex_unlock(&gdev->reg_mutex);
 165 }
 166
 167 static ssize_t ccwgroup_ungroup_store(struct device *dev,
 168                                       struct device_attribute *attr,
 169                                       const char *buf, size_t count)
 170 {
 171         struct ccwgroup_device *gdev = to_ccwgroupdev(dev);
 172         int rc = 0;
 173
 174         /* Prevent concurrent online/offline processing and ungrouping. */
 175         if (atomic_cmpxchg(&gdev->onoff, 0, 1) != 0)
 176                 return -EAGAIN;
 177         if (gdev->state != CCWGROUP_OFFLINE) {
 178                 rc = -EINVAL;
 179                 goto out;
 180         }
 181
 182         if (device_remove_file_self(dev, attr))
 183                 ccwgroup_ungroup(gdev);
 184         else
 185                 rc = -ENODEV;
 186 out:
 187         if (rc) {
 188                 /* Release onoff "lock" when ungrouping failed. */
 189                 atomic_set(&gdev->onoff, 0);
 190                 return rc;
 191         }
 192         return count;
 193 }
 194 static DEVICE_ATTR(ungroup, 0200, NULL, ccwgroup_ungroup_store);
 195 static DEVICE_ATTR(online, 0644, ccwgroup_online_show, ccwgroup_online_store);
 196
 197 static struct attribute *ccwgroup_dev_attrs[] = {
 198         &dev_attr_online.attr,
 199         &dev_attr_ungroup.attr,
 200         NULL,
 201 };
 202 ATTRIBUTE_GROUPS(ccwgroup_dev);
 203
 204 static void ccwgroup_ungroup_workfn(struct work_struct *work)
 205 {
 206         struct ccwgroup_device *gdev =
 207                 container_of(work, struct ccwgroup_device, ungroup_work);
 208
 209         ccwgroup_ungroup(gdev);
 210         put_device(&gdev->dev);
 211 }
 212
 213 static void ccwgroup_release(struct device *dev)
 214 {
 215         struct ccwgroup_device *gdev = to_ccwgroupdev(dev);
 216         unsigned int i;
 217
 218         for (i = 0; i < gdev->count; i++) {
 219                 struct ccw_device *cdev = gdev->cdev[i];
 220                 unsigned long flags;
 221
 222                 if (cdev) {
 223                         spin_lock_irqsave(cdev->ccwlock, flags);
 224                         if (dev_get_drvdata(&cdev->dev) == gdev)
 225                                 dev_set_drvdata(&cdev->dev, NULL);
 226                         spin_unlock_irqrestore(cdev->ccwlock, flags);
 227                         put_device(&cdev->dev);
 228                 }
 229         }
 230
 231         kfree(gdev);
 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                         while (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                         while (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         mutex_unlock(&gdev->reg_mutex);
 400         put_device(&gdev->dev);
 401         return rc;
 402 }
 403 EXPORT_SYMBOL(ccwgroup_create_dev);
 404
 405 static int ccwgroup_notifier(struct notifier_block *nb, unsigned long action,
 406                              void *data)
 407 {
 408         struct ccwgroup_device *gdev = to_ccwgroupdev(data);
 409
 410         if (action == BUS_NOTIFY_UNBOUND_DRIVER) {
 411                 get_device(&gdev->dev);
 412                 schedule_work(&gdev->ungroup_work);
 413         }
 414
 415         return NOTIFY_OK;
 416 }
 417
 418 static struct notifier_block ccwgroup_nb = {
 419         .notifier_call = ccwgroup_notifier
 420 };
 421
 422 static int __init init_ccwgroup(void)
 423 {
 424         int ret;
 425
 426         ret = bus_register(&ccwgroup_bus_type);
 427         if (ret)
 428                 return ret;
 429
 430         ret = bus_register_notifier(&ccwgroup_bus_type, &ccwgroup_nb);
 431         if (ret)
 432                 bus_unregister(&ccwgroup_bus_type);
 433
 434         return ret;
 435 }
 436
 437 static void __exit cleanup_ccwgroup(void)
 438 {
 439         bus_unregister_notifier(&ccwgroup_bus_type, &ccwgroup_nb);
 440         bus_unregister(&ccwgroup_bus_type);
 441 }
 442
 443 module_init(init_ccwgroup);
 444 module_exit(cleanup_ccwgroup);
 445
 446 /************************** driver stuff ******************************/
 447
 448 static void ccwgroup_remove(struct device *dev)
 449 {
 450         struct ccwgroup_device *gdev = to_ccwgroupdev(dev);
 451         struct ccwgroup_driver *gdrv = to_ccwgroupdrv(dev->driver);
 452
 453         if (gdrv->remove)
 454                 gdrv->remove(gdev);
 455 }
 456
 457 static void ccwgroup_shutdown(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;
 464         if (gdrv->shutdown)
 465                 gdrv->shutdown(gdev);
 466 }
 467
 468 static const struct bus_type ccwgroup_bus_type = {
 469         .name   = "ccwgroup",
 470         .dev_groups = ccwgroup_dev_groups,
 471         .remove = ccwgroup_remove,
 472         .shutdown = ccwgroup_shutdown,
 473 };
 474
 475 bool dev_is_ccwgroup(struct device *dev)
 476 {
 477         return dev->bus == &ccwgroup_bus_type;
 478 }
 479 EXPORT_SYMBOL(dev_is_ccwgroup);
 480
 481 /**
 482  * ccwgroup_driver_register() - register a ccw group driver
 483  * @cdriver: driver to be registered
 484  *
 485  * This function is mainly a wrapper around driver_register().
 486  */
 487 int ccwgroup_driver_register(struct ccwgroup_driver *cdriver)
 488 {
 489         /* register our new driver with the core */
 490         cdriver->driver.bus = &ccwgroup_bus_type;
 491
 492         return driver_register(&cdriver->driver);
 493 }
 494 EXPORT_SYMBOL(ccwgroup_driver_register);
 495
 496 /**
 497  * ccwgroup_driver_unregister() - deregister a ccw group driver
 498  * @cdriver: driver to be deregistered
 499  *
 500  * This function is mainly a wrapper around driver_unregister().
 501  */
 502 void ccwgroup_driver_unregister(struct ccwgroup_driver *cdriver)
 503 {
 504         driver_unregister(&cdriver->driver);
 505 }
 506 EXPORT_SYMBOL(ccwgroup_driver_unregister);
 507
 508 /**
 509  * ccwgroup_probe_ccwdev() - probe function for slave devices
 510  * @cdev: ccw device to be probed
 511  *
 512  * This is a dummy probe function for ccw devices that are slave devices in
 513  * a ccw group device.
 514  * Returns:
 515  *  always %0
 516  */
 517 int ccwgroup_probe_ccwdev(struct ccw_device *cdev)
 518 {
 519         return 0;
 520 }
 521 EXPORT_SYMBOL(ccwgroup_probe_ccwdev);
 522
 523 /**
 524  * ccwgroup_remove_ccwdev() - remove function for slave devices
 525  * @cdev: ccw device to be removed
 526  *
 527  * This is a remove function for ccw devices that are slave devices in a ccw
 528  * group device. It sets the ccw device offline and also deregisters the
 529  * embedding ccw group device.
 530  */
 531 void ccwgroup_remove_ccwdev(struct ccw_device *cdev)
 532 {
 533         struct ccwgroup_device *gdev;
 534
 535         /* Ignore offlining errors, device is gone anyway. */
 536         ccw_device_set_offline(cdev);
 537         /* If one of its devices is gone, the whole group is done for. */
 538         spin_lock_irq(cdev->ccwlock);
 539         gdev = dev_get_drvdata(&cdev->dev);
 540         if (!gdev) {
 541                 spin_unlock_irq(cdev->ccwlock);
 542                 return;
 543         }
 544         /* Get ccwgroup device reference for local processing. */
 545         get_device(&gdev->dev);
 546         spin_unlock_irq(cdev->ccwlock);
 547         /* Unregister group device. */
 548         ccwgroup_ungroup(gdev);
 549         /* Release ccwgroup device reference for local processing. */
 550         put_device(&gdev->dev);
 551 }
 552 EXPORT_SYMBOL(ccwgroup_remove_ccwdev);
 553 MODULE_DESCRIPTION("ccwgroup bus driver");
 554 MODULE_LICENSE("GPL");