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