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         pci_bus_put(slot->bus);
  83
  84         kfree(slot);
  85 }
  86
  87 static struct pci_slot_attribute pci_slot_attr_address =
  88         __ATTR(address, S_IRUGO, address_read_file, NULL);
  89 static struct pci_slot_attribute pci_slot_attr_max_speed =
  90         __ATTR(max_bus_speed, S_IRUGO, max_speed_read_file, NULL);
  91 static struct pci_slot_attribute pci_slot_attr_cur_speed =
  92         __ATTR(cur_bus_speed, S_IRUGO, cur_speed_read_file, NULL);
  93
  94 static struct attribute *pci_slot_default_attrs[] = {
  95         &pci_slot_attr_address.attr,
  96         &pci_slot_attr_max_speed.attr,
  97         &pci_slot_attr_cur_speed.attr,
  98         NULL,
  99 };
 100 ATTRIBUTE_GROUPS(pci_slot_default);
 101
 102 static const struct kobj_type pci_slot_ktype = {
 103         .sysfs_ops = &pci_slot_sysfs_ops,
 104         .release = &pci_slot_release,
 105         .default_groups = pci_slot_default_groups,
 106 };
 107
 108 static char *make_slot_name(const char *name)
 109 {
 110         char *new_name;
 111         int len, max, dup;
 112
 113         new_name = kstrdup(name, GFP_KERNEL);
 114         if (!new_name)
 115                 return NULL;
 116
 117         /*
 118          * Make sure we hit the realloc case the first time through the
 119          * loop.  'len' will be strlen(name) + 3 at that point which is
 120          * enough space for "name-X" and the trailing NUL.
 121          */
 122         len = strlen(name) + 2;
 123         max = 1;
 124         dup = 1;
 125
 126         for (;;) {
 127                 struct kobject *dup_slot;
 128                 dup_slot = kset_find_obj(pci_slots_kset, new_name);
 129                 if (!dup_slot)
 130                         break;
 131                 kobject_put(dup_slot);
 132                 if (dup == max) {
 133                         len++;
 134                         max *= 10;
 135                         kfree(new_name);
 136                         new_name = kmalloc(len, GFP_KERNEL);
 137                         if (!new_name)
 138                                 break;
 139                 }
 140                 sprintf(new_name, "%s-%d", name, dup++);
 141         }
 142
 143         return new_name;
 144 }
 145
 146 static int rename_slot(struct pci_slot *slot, const char *name)
 147 {
 148         int result = 0;
 149         char *slot_name;
 150
 151         if (strcmp(pci_slot_name(slot), name) == 0)
 152                 return result;
 153
 154         slot_name = make_slot_name(name);
 155         if (!slot_name)
 156                 return -ENOMEM;
 157
 158         result = kobject_rename(&slot->kobj, slot_name);
 159         kfree(slot_name);
 160
 161         return result;
 162 }
 163
 164 void pci_dev_assign_slot(struct pci_dev *dev)
 165 {
 166         struct pci_slot *slot;
 167
 168         mutex_lock(&pci_slot_mutex);
 169         list_for_each_entry(slot, &dev->bus->slots, list)
 170                 if (PCI_SLOT(dev->devfn) == slot->number)
 171                         dev->slot = slot;
 172         mutex_unlock(&pci_slot_mutex);
 173 }
 174
 175 static struct pci_slot *get_slot(struct pci_bus *parent, int slot_nr)
 176 {
 177         struct pci_slot *slot;
 178
 179         /* We already hold pci_slot_mutex */
 180         list_for_each_entry(slot, &parent->slots, list)
 181                 if (slot->number == slot_nr) {
 182                         kobject_get(&slot->kobj);
 183                         return slot;
 184                 }
 185
 186         return NULL;
 187 }
 188
 189 /**
 190  * pci_create_slot - create or increment refcount for physical PCI slot
 191  * @parent: struct pci_bus of parent bridge
 192  * @slot_nr: PCI_SLOT(pci_dev->devfn) or -1 for placeholder
 193  * @name: user visible string presented in /sys/bus/pci/slots/<name>
 194  * @hotplug: set if caller is hotplug driver, NULL otherwise
 195  *
 196  * PCI slots have first class attributes such as address, speed, width,
 197  * and a &struct pci_slot is used to manage them. This interface will
 198  * either return a new &struct pci_slot to the caller, or if the pci_slot
 199  * already exists, its refcount will be incremented.
 200  *
 201  * Slots are uniquely identified by a @pci_bus, @slot_nr tuple.
 202  *
 203  * There are known platforms with broken firmware that assign the same
 204  * name to multiple slots. Workaround these broken platforms by renaming
 205  * the slots on behalf of the caller. If firmware assigns name N to
 206  * multiple slots:
 207  *
 208  * The first slot is assigned N
 209  * The second slot is assigned N-1
 210  * The third slot is assigned N-2
 211  * etc.
 212  *
 213  * Placeholder slots:
 214  * In most cases, @pci_bus, @slot_nr will be sufficient to uniquely identify
 215  * a slot. There is one notable exception - pSeries (rpaphp), where the
 216  * @slot_nr cannot be determined until a device is actually inserted into
 217  * the slot. In this scenario, the caller may pass -1 for @slot_nr.
 218  *
 219  * The following semantics are imposed when the caller passes @slot_nr ==
 220  * -1. First, we no longer check for an existing %struct pci_slot, as there
 221  * may be many slots with @slot_nr of -1.  The other change in semantics is
 222  * user-visible, which is the 'address' parameter presented in sysfs will
 223  * consist solely of a dddd:bb tuple, where dddd is the PCI domain of the
 224  * %struct pci_bus and bb is the bus number. In other words, the devfn of
 225  * the 'placeholder' slot will not be displayed.
 226  */
 227 struct pci_slot *pci_create_slot(struct pci_bus *parent, int slot_nr,
 228                                  const char *name,
 229                                  struct hotplug_slot *hotplug)
 230 {
 231         struct pci_dev *dev;
 232         struct pci_slot *slot;
 233         int err = 0;
 234         char *slot_name = NULL;
 235
 236         mutex_lock(&pci_slot_mutex);
 237
 238         if (slot_nr == -1)
 239                 goto placeholder;
 240
 241         /*
 242          * Hotplug drivers are allowed to rename an existing slot,
 243          * but only if not already claimed.
 244          */
 245         slot = get_slot(parent, slot_nr);
 246         if (slot) {
 247                 if (hotplug) {
 248                         if (slot->hotplug) {
 249                                 err = -EBUSY;
 250                                 goto put_slot;
 251                         }
 252                         err = rename_slot(slot, name);
 253                         if (err)
 254                                 goto put_slot;
 255                 }
 256                 goto out;
 257         }
 258
 259 placeholder:
 260         slot = kzalloc(sizeof(*slot), GFP_KERNEL);
 261         if (!slot) {
 262                 err = -ENOMEM;
 263                 goto err;
 264         }
 265
 266         slot->bus = pci_bus_get(parent);
 267         slot->number = slot_nr;
 268
 269         slot->kobj.kset = pci_slots_kset;
 270
 271         slot_name = make_slot_name(name);
 272         if (!slot_name) {
 273                 err = -ENOMEM;
 274                 pci_bus_put(slot->bus);
 275                 kfree(slot);
 276                 goto err;
 277         }
 278
 279         INIT_LIST_HEAD(&slot->list);
 280         list_add(&slot->list, &parent->slots);
 281
 282         err = kobject_init_and_add(&slot->kobj, &pci_slot_ktype, NULL,
 283                                    "%s", slot_name);
 284         if (err)
 285                 goto put_slot;
 286
 287         down_read(&pci_bus_sem);
 288         list_for_each_entry(dev, &parent->devices, bus_list)
 289                 if (PCI_SLOT(dev->devfn) == slot_nr)
 290                         dev->slot = slot;
 291         up_read(&pci_bus_sem);
 292
 293         dev_dbg(&parent->dev, "dev %02x, created physical slot %s\n",
 294                 slot_nr, pci_slot_name(slot));
 295
 296 out:
 297         kfree(slot_name);
 298         mutex_unlock(&pci_slot_mutex);
 299         return slot;
 300
 301 put_slot:
 302         kobject_put(&slot->kobj);
 303 err:
 304         slot = ERR_PTR(err);
 305         goto out;
 306 }
 307 EXPORT_SYMBOL_GPL(pci_create_slot);
 308
 309 /**
 310  * pci_destroy_slot - decrement refcount for physical PCI slot
 311  * @slot: struct pci_slot to decrement
 312  *
 313  * %struct pci_slot is refcounted, so destroying them is really easy; we
 314  * just call kobject_put on its kobj and let our release methods do the
 315  * rest.
 316  */
 317 void pci_destroy_slot(struct pci_slot *slot)
 318 {
 319         dev_dbg(&slot->bus->dev, "dev %02x, dec refcount to %d\n",
 320                 slot->number, kref_read(&slot->kobj.kref) - 1);
 321
 322         mutex_lock(&pci_slot_mutex);
 323         kobject_put(&slot->kobj);
 324         mutex_unlock(&pci_slot_mutex);
 325 }
 326 EXPORT_SYMBOL_GPL(pci_destroy_slot);
 327
 328 #if defined(CONFIG_HOTPLUG_PCI) || defined(CONFIG_HOTPLUG_PCI_MODULE)
 329 #include <linux/pci_hotplug.h>
 330 /**
 331  * pci_hp_create_module_link - create symbolic link to hotplug driver module
 332  * @pci_slot: struct pci_slot
 333  *
 334  * Helper function for pci_hotplug_core.c to create symbolic link to
 335  * the hotplug driver module.
 336  */
 337 void pci_hp_create_module_link(struct pci_slot *pci_slot)
 338 {
 339         struct hotplug_slot *slot = pci_slot->hotplug;
 340         struct kobject *kobj = NULL;
 341         int ret;
 342
 343         if (!slot || !slot->ops)
 344                 return;
 345         kobj = kset_find_obj(module_kset, slot->mod_name);
 346         if (!kobj)
 347                 return;
 348         ret = sysfs_create_link(&pci_slot->kobj, kobj, "module");
 349         if (ret)
 350                 dev_err(&pci_slot->bus->dev, "Error creating sysfs link (%d)\n",
 351                         ret);
 352         kobject_put(kobj);
 353 }
 354 EXPORT_SYMBOL_GPL(pci_hp_create_module_link);
 355
 356 /**
 357  * pci_hp_remove_module_link - remove symbolic link to the hotplug driver
 358  *      module.
 359  * @pci_slot: struct pci_slot
 360  *
 361  * Helper function for pci_hotplug_core.c to remove symbolic link to
 362  * the hotplug driver module.
 363  */
 364 void pci_hp_remove_module_link(struct pci_slot *pci_slot)
 365 {
 366         sysfs_remove_link(&pci_slot->kobj, "module");
 367 }
 368 EXPORT_SYMBOL_GPL(pci_hp_remove_module_link);
 369 #endif
 370
 371 static int pci_slot_init(void)
 372 {
 373         struct kset *pci_bus_kset;
 374
 375         pci_bus_kset = bus_get_kset(&pci_bus_type);
 376         pci_slots_kset = kset_create_and_add("slots", NULL,
 377                                                 &pci_bus_kset->kobj);
 378         if (!pci_slots_kset) {
 379                 pr_err("PCI: Slot initialization failure\n");
 380                 return -ENOMEM;
 381         }
 382         return 0;
 383 }
 384
 385 subsys_initcall(pci_slot_init);