drivers/pci/slot.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2006 Matthew Wilcox <matthew@wil.cx>
   4  * Copyright (C) 2006-2009 Hewlett-Packard Development Company, L.P.
   5  *      Alex Chiang <achiang@hp.com>
   6  */
   7
   8 #include <linux/kobject.h>
   9 #include <linux/slab.h>
  10 #include <linux/module.h>
  11 #include <linux/pci.h>
  12 #include <linux/err.h>
  13 #include "pci.h"
  14
  15 struct kset *pci_slots_kset;
  16 EXPORT_SYMBOL_GPL(pci_slots_kset);
  17
  18 static ssize_t pci_slot_attr_show(struct kobject *kobj,
  19                                         struct attribute *attr, char *buf)
  20 {
  21         struct pci_slot *slot = to_pci_slot(kobj);
  22         struct pci_slot_attribute *attribute = to_pci_slot_attr(attr);
  23         return attribute->show ? attribute->show(slot, buf) : -EIO;
  24 }
  25
  26 static ssize_t pci_slot_attr_store(struct kobject *kobj,
  27                         struct attribute *attr, const char *buf, size_t len)
  28 {
  29         struct pci_slot *slot = to_pci_slot(kobj);
  30         struct pci_slot_attribute *attribute = to_pci_slot_attr(attr);
  31         return attribute->store ? attribute->store(slot, buf, len) : -EIO;
  32 }
  33
  34 static const struct sysfs_ops pci_slot_sysfs_ops = {
  35         .show = pci_slot_attr_show,
  36         .store = pci_slot_attr_store,
  37 };
  38
  39 static ssize_t address_read_file(struct pci_slot *slot, char *buf)
  40 {
  41         if (slot->number == 0xff)
  42                 return sysfs_emit(buf, "%04x:%02x\n",
  43                                   pci_domain_nr(slot->bus),
  44                                   slot->bus->number);
  45
  46         return sysfs_emit(buf, "%04x:%02x:%02x\n",
  47                           pci_domain_nr(slot->bus),
  48                           slot->bus->number,
  49                           slot->number);
  50 }
  51
  52 static ssize_t bus_speed_read(enum pci_bus_speed speed, char *buf)
  53 {
  54         return sysfs_emit(buf, "%s\n", pci_speed_string(speed));
  55 }
  56
  57 static ssize_t max_speed_read_file(struct pci_slot *slot, char *buf)
  58 {
  59         return bus_speed_read(slot->bus->max_bus_speed, buf);
  60 }
  61
  62 static ssize_t cur_speed_read_file(struct pci_slot *slot, char *buf)
  63 {
  64         return bus_speed_read(slot->bus->cur_bus_speed, buf);
  65 }
  66
  67 static void pci_slot_release(struct kobject *kobj)
  68 {
  69         struct pci_dev *dev;
  70         struct pci_slot *slot = to_pci_slot(kobj);
  71
  72         dev_dbg(&slot->bus->dev, "dev %02x, released physical slot %s\n",
  73                 slot->number, pci_slot_name(slot));
  74
  75         down_read(&pci_bus_sem);
  76         list_for_each_entry(dev, &slot->bus->devices, bus_list)
  77                 if (PCI_SLOT(dev->devfn) == slot->number)
  78                         dev->slot = NULL;
  79         up_read(&pci_bus_sem);
  80
  81         list_del(&slot->list);
  82
  83         kfree(slot);
  84 }
  85
  86 static struct pci_slot_attribute pci_slot_attr_address =
  87         __ATTR(address, S_IRUGO, address_read_file, NULL);
  88 static struct pci_slot_attribute pci_slot_attr_max_speed =
  89         __ATTR(max_bus_speed, S_IRUGO, max_speed_read_file, NULL);
  90 static struct pci_slot_attribute pci_slot_attr_cur_speed =
  91         __ATTR(cur_bus_speed, S_IRUGO, cur_speed_read_file, NULL);
  92
  93 static struct attribute *pci_slot_default_attrs[] = {
  94         &pci_slot_attr_address.attr,
  95         &pci_slot_attr_max_speed.attr,
  96         &pci_slot_attr_cur_speed.attr,
  97         NULL,
  98 };
  99
 100 static struct kobj_type pci_slot_ktype = {
 101         .sysfs_ops = &pci_slot_sysfs_ops,
 102         .release = &pci_slot_release,
 103         .default_attrs = pci_slot_default_attrs,
 104 };
 105
 106 static char *make_slot_name(const char *name)
 107 {
 108         char *new_name;
 109         int len, max, dup;
 110
 111         new_name = kstrdup(name, GFP_KERNEL);
 112         if (!new_name)
 113                 return NULL;
 114
 115         /*
 116          * Make sure we hit the realloc case the first time through the
 117          * loop.  'len' will be strlen(name) + 3 at that point which is
 118          * enough space for "name-X" and the trailing NUL.
 119          */
 120         len = strlen(name) + 2;
 121         max = 1;
 122         dup = 1;
 123
 124         for (;;) {
 125                 struct kobject *dup_slot;
 126                 dup_slot = kset_find_obj(pci_slots_kset, new_name);
 127                 if (!dup_slot)
 128                         break;
 129                 kobject_put(dup_slot);
 130                 if (dup == max) {
 131                         len++;
 132                         max *= 10;
 133                         kfree(new_name);
 134                         new_name = kmalloc(len, GFP_KERNEL);
 135                         if (!new_name)
 136                                 break;
 137                 }
 138                 sprintf(new_name, "%s-%d", name, dup++);
 139         }
 140
 141         return new_name;
 142 }
 143
 144 static int rename_slot(struct pci_slot *slot, const char *name)
 145 {
 146         int result = 0;
 147         char *slot_name;
 148
 149         if (strcmp(pci_slot_name(slot), name) == 0)
 150                 return result;
 151
 152         slot_name = make_slot_name(name);
 153         if (!slot_name)
 154                 return -ENOMEM;
 155
 156         result = kobject_rename(&slot->kobj, slot_name);
 157         kfree(slot_name);
 158
 159         return result;
 160 }
 161
 162 void pci_dev_assign_slot(struct pci_dev *dev)
 163 {
 164         struct pci_slot *slot;
 165
 166         mutex_lock(&pci_slot_mutex);
 167         list_for_each_entry(slot, &dev->bus->slots, list)
 168                 if (PCI_SLOT(dev->devfn) == slot->number)
 169                         dev->slot = slot;
 170         mutex_unlock(&pci_slot_mutex);
 171 }
 172
 173 static struct pci_slot *get_slot(struct pci_bus *parent, int slot_nr)
 174 {
 175         struct pci_slot *slot;
 176
 177         /* We already hold pci_slot_mutex */
 178         list_for_each_entry(slot, &parent->slots, list)
 179                 if (slot->number == slot_nr) {
 180                         kobject_get(&slot->kobj);
 181                         return slot;
 182                 }
 183
 184         return NULL;
 185 }
 186
 187 /**
 188  * pci_create_slot - create or increment refcount for physical PCI slot
 189  * @parent: struct pci_bus of parent bridge
 190  * @slot_nr: PCI_SLOT(pci_dev->devfn) or -1 for placeholder
 191  * @name: user visible string presented in /sys/bus/pci/slots/<name>
 192  * @hotplug: set if caller is hotplug driver, NULL otherwise
 193  *
 194  * PCI slots have first class attributes such as address, speed, width,
 195  * and a &struct pci_slot is used to manage them. This interface will
 196  * either return a new &struct pci_slot to the caller, or if the pci_slot
 197  * already exists, its refcount will be incremented.
 198  *
 199  * Slots are uniquely identified by a @pci_bus, @slot_nr tuple.
 200  *
 201  * There are known platforms with broken firmware that assign the same
 202  * name to multiple slots. Workaround these broken platforms by renaming
 203  * the slots on behalf of the caller. If firmware assigns name N to
 204  * multiple slots:
 205  *
 206  * The first slot is assigned N
 207  * The second slot is assigned N-1
 208  * The third slot is assigned N-2
 209  * etc.
 210  *
 211  * Placeholder slots:
 212  * In most cases, @pci_bus, @slot_nr will be sufficient to uniquely identify
 213  * a slot. There is one notable exception - pSeries (rpaphp), where the
 214  * @slot_nr cannot be determined until a device is actually inserted into
 215  * the slot. In this scenario, the caller may pass -1 for @slot_nr.
 216  *
 217  * The following semantics are imposed when the caller passes @slot_nr ==
 218  * -1. First, we no longer check for an existing %struct pci_slot, as there
 219  * may be many slots with @slot_nr of -1.  The other change in semantics is
 220  * user-visible, which is the 'address' parameter presented in sysfs will
 221  * consist solely of a dddd:bb tuple, where dddd is the PCI domain of the
 222  * %struct pci_bus and bb is the bus number. In other words, the devfn of
 223  * the 'placeholder' slot will not be displayed.
 224  */
 225 struct pci_slot *pci_create_slot(struct pci_bus *parent, int slot_nr,
 226                                  const char *name,
 227                                  struct hotplug_slot *hotplug)
 228 {
 229         struct pci_dev *dev;
 230         struct pci_slot *slot;
 231         int err = 0;
 232         char *slot_name = NULL;
 233
 234         mutex_lock(&pci_slot_mutex);
 235
 236         if (slot_nr == -1)
 237                 goto placeholder;
 238
 239         /*
 240          * Hotplug drivers are allowed to rename an existing slot,
 241          * but only if not already claimed.
 242          */
 243         slot = get_slot(parent, slot_nr);
 244         if (slot) {
 245                 if (hotplug) {
 246                         if ((err = slot->hotplug ? -EBUSY : 0)
 247                              || (err = rename_slot(slot, name))) {
 248                                 kobject_put(&slot->kobj);
 249                                 slot = NULL;
 250                                 goto err;
 251                         }
 252                 }
 253                 goto out;
 254         }
 255
 256 placeholder:
 257         slot = kzalloc(sizeof(*slot), GFP_KERNEL);
 258         if (!slot) {
 259                 err = -ENOMEM;
 260                 goto err;
 261         }
 262
 263         slot->bus = parent;
 264         slot->number = slot_nr;
 265
 266         slot->kobj.kset = pci_slots_kset;
 267
 268         slot_name = make_slot_name(name);
 269         if (!slot_name) {
 270                 err = -ENOMEM;
 271                 kfree(slot);
 272                 goto err;
 273         }
 274
 275         INIT_LIST_HEAD(&slot->list);
 276         list_add(&slot->list, &parent->slots);
 277
 278         err = kobject_init_and_add(&slot->kobj, &pci_slot_ktype, NULL,
 279                                    "%s", slot_name);
 280         if (err) {
 281                 kobject_put(&slot->kobj);
 282                 goto err;
 283         }
 284
 285         down_read(&pci_bus_sem);
 286         list_for_each_entry(dev, &parent->devices, bus_list)
 287                 if (PCI_SLOT(dev->devfn) == slot_nr)
 288                         dev->slot = slot;
 289         up_read(&pci_bus_sem);
 290
 291         dev_dbg(&parent->dev, "dev %02x, created physical slot %s\n",
 292                 slot_nr, pci_slot_name(slot));
 293
 294 out:
 295         kfree(slot_name);
 296         mutex_unlock(&pci_slot_mutex);
 297         return slot;
 298 err:
 299         slot = ERR_PTR(err);
 300         goto out;
 301 }
 302 EXPORT_SYMBOL_GPL(pci_create_slot);
 303
 304 /**
 305  * pci_destroy_slot - decrement refcount for physical PCI slot
 306  * @slot: struct pci_slot to decrement
 307  *
 308  * %struct pci_slot is refcounted, so destroying them is really easy; we
 309  * just call kobject_put on its kobj and let our release methods do the
 310  * rest.
 311  */
 312 void pci_destroy_slot(struct pci_slot *slot)
 313 {
 314         dev_dbg(&slot->bus->dev, "dev %02x, dec refcount to %d\n",
 315                 slot->number, kref_read(&slot->kobj.kref) - 1);
 316
 317         mutex_lock(&pci_slot_mutex);
 318         kobject_put(&slot->kobj);
 319         mutex_unlock(&pci_slot_mutex);
 320 }
 321 EXPORT_SYMBOL_GPL(pci_destroy_slot);
 322
 323 #if defined(CONFIG_HOTPLUG_PCI) || defined(CONFIG_HOTPLUG_PCI_MODULE)
 324 #include <linux/pci_hotplug.h>
 325 /**
 326  * pci_hp_create_module_link - create symbolic link to hotplug driver module
 327  * @pci_slot: struct pci_slot
 328  *
 329  * Helper function for pci_hotplug_core.c to create symbolic link to
 330  * the hotplug driver module.
 331  */
 332 void pci_hp_create_module_link(struct pci_slot *pci_slot)
 333 {
 334         struct hotplug_slot *slot = pci_slot->hotplug;
 335         struct kobject *kobj = NULL;
 336         int ret;
 337
 338         if (!slot || !slot->ops)
 339                 return;
 340         kobj = kset_find_obj(module_kset, slot->mod_name);
 341         if (!kobj)
 342                 return;
 343         ret = sysfs_create_link(&pci_slot->kobj, kobj, "module");
 344         if (ret)
 345                 dev_err(&pci_slot->bus->dev, "Error creating sysfs link (%d)\n",
 346                         ret);
 347         kobject_put(kobj);
 348 }
 349 EXPORT_SYMBOL_GPL(pci_hp_create_module_link);
 350
 351 /**
 352  * pci_hp_remove_module_link - remove symbolic link to the hotplug driver
 353  *      module.
 354  * @pci_slot: struct pci_slot
 355  *
 356  * Helper function for pci_hotplug_core.c to remove symbolic link to
 357  * the hotplug driver module.
 358  */
 359 void pci_hp_remove_module_link(struct pci_slot *pci_slot)
 360 {
 361         sysfs_remove_link(&pci_slot->kobj, "module");
 362 }
 363 EXPORT_SYMBOL_GPL(pci_hp_remove_module_link);
 364 #endif
 365
 366 static int pci_slot_init(void)
 367 {
 368         struct kset *pci_bus_kset;
 369
 370         pci_bus_kset = bus_get_kset(&pci_bus_type);
 371         pci_slots_kset = kset_create_and_add("slots", NULL,
 372                                                 &pci_bus_kset->kobj);
 373         if (!pci_slots_kset) {
 374                 pr_err("PCI: Slot initialization failure\n");
 375                 return -ENOMEM;
 376         }
 377         return 0;
 378 }
 379
 380 subsys_initcall(pci_slot_init);