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 sprintf(buf, "%04x:%02x\n",
  43                                 pci_domain_nr(slot->bus),
  44                                 slot->bus->number);
  45         else
  46                 return sprintf(buf, "%04x:%02x:%02x\n",
  47                                 pci_domain_nr(slot->bus),
  48                                 slot->bus->number,
  49                                 slot->number);
  50 }
  51
  52 /* these strings match up with the values in pci_bus_speed */
  53 static const char *pci_bus_speed_strings[] = {
  54         "33 MHz PCI",           /* 0x00 */
  55         "66 MHz PCI",           /* 0x01 */
  56         "66 MHz PCI-X",         /* 0x02 */
  57         "100 MHz PCI-X",        /* 0x03 */
  58         "133 MHz PCI-X",        /* 0x04 */
  59         NULL,                   /* 0x05 */
  60         NULL,                   /* 0x06 */
  61         NULL,                   /* 0x07 */
  62         NULL,                   /* 0x08 */
  63         "66 MHz PCI-X 266",     /* 0x09 */
  64         "100 MHz PCI-X 266",    /* 0x0a */
  65         "133 MHz PCI-X 266",    /* 0x0b */
  66         "Unknown AGP",          /* 0x0c */
  67         "1x AGP",               /* 0x0d */
  68         "2x AGP",               /* 0x0e */
  69         "4x AGP",               /* 0x0f */
  70         "8x AGP",               /* 0x10 */
  71         "66 MHz PCI-X 533",     /* 0x11 */
  72         "100 MHz PCI-X 533",    /* 0x12 */
  73         "133 MHz PCI-X 533",    /* 0x13 */
  74         "2.5 GT/s PCIe",        /* 0x14 */
  75         "5.0 GT/s PCIe",        /* 0x15 */
  76         "8.0 GT/s PCIe",        /* 0x16 */
  77         "16.0 GT/s PCIe",       /* 0x17 */
  78 };
  79
  80 static ssize_t bus_speed_read(enum pci_bus_speed speed, char *buf)
  81 {
  82         const char *speed_string;
  83
  84         if (speed < ARRAY_SIZE(pci_bus_speed_strings))
  85                 speed_string = pci_bus_speed_strings[speed];
  86         else
  87                 speed_string = "Unknown";
  88
  89         return sprintf(buf, "%s\n", speed_string);
  90 }
  91
  92 static ssize_t max_speed_read_file(struct pci_slot *slot, char *buf)
  93 {
  94         return bus_speed_read(slot->bus->max_bus_speed, buf);
  95 }
  96
  97 static ssize_t cur_speed_read_file(struct pci_slot *slot, char *buf)
  98 {
  99         return bus_speed_read(slot->bus->cur_bus_speed, buf);
 100 }
 101
 102 static void pci_slot_release(struct kobject *kobj)
 103 {
 104         struct pci_dev *dev;
 105         struct pci_slot *slot = to_pci_slot(kobj);
 106
 107         dev_dbg(&slot->bus->dev, "dev %02x, released physical slot %s\n",
 108                 slot->number, pci_slot_name(slot));
 109
 110         down_read(&pci_bus_sem);
 111         list_for_each_entry(dev, &slot->bus->devices, bus_list)
 112                 if (PCI_SLOT(dev->devfn) == slot->number)
 113                         dev->slot = NULL;
 114         up_read(&pci_bus_sem);
 115
 116         list_del(&slot->list);
 117
 118         kfree(slot);
 119 }
 120
 121 static struct pci_slot_attribute pci_slot_attr_address =
 122         __ATTR(address, S_IRUGO, address_read_file, NULL);
 123 static struct pci_slot_attribute pci_slot_attr_max_speed =
 124         __ATTR(max_bus_speed, S_IRUGO, max_speed_read_file, NULL);
 125 static struct pci_slot_attribute pci_slot_attr_cur_speed =
 126         __ATTR(cur_bus_speed, S_IRUGO, cur_speed_read_file, NULL);
 127
 128 static struct attribute *pci_slot_default_attrs[] = {
 129         &pci_slot_attr_address.attr,
 130         &pci_slot_attr_max_speed.attr,
 131         &pci_slot_attr_cur_speed.attr,
 132         NULL,
 133 };
 134
 135 static struct kobj_type pci_slot_ktype = {
 136         .sysfs_ops = &pci_slot_sysfs_ops,
 137         .release = &pci_slot_release,
 138         .default_attrs = pci_slot_default_attrs,
 139 };
 140
 141 static char *make_slot_name(const char *name)
 142 {
 143         char *new_name;
 144         int len, max, dup;
 145
 146         new_name = kstrdup(name, GFP_KERNEL);
 147         if (!new_name)
 148                 return NULL;
 149
 150         /*
 151          * Make sure we hit the realloc case the first time through the
 152          * loop.  'len' will be strlen(name) + 3 at that point which is
 153          * enough space for "name-X" and the trailing NUL.
 154          */
 155         len = strlen(name) + 2;
 156         max = 1;
 157         dup = 1;
 158
 159         for (;;) {
 160                 struct kobject *dup_slot;
 161                 dup_slot = kset_find_obj(pci_slots_kset, new_name);
 162                 if (!dup_slot)
 163                         break;
 164                 kobject_put(dup_slot);
 165                 if (dup == max) {
 166                         len++;
 167                         max *= 10;
 168                         kfree(new_name);
 169                         new_name = kmalloc(len, GFP_KERNEL);
 170                         if (!new_name)
 171                                 break;
 172                 }
 173                 sprintf(new_name, "%s-%d", name, dup++);
 174         }
 175
 176         return new_name;
 177 }
 178
 179 static int rename_slot(struct pci_slot *slot, const char *name)
 180 {
 181         int result = 0;
 182         char *slot_name;
 183
 184         if (strcmp(pci_slot_name(slot), name) == 0)
 185                 return result;
 186
 187         slot_name = make_slot_name(name);
 188         if (!slot_name)
 189                 return -ENOMEM;
 190
 191         result = kobject_rename(&slot->kobj, slot_name);
 192         kfree(slot_name);
 193
 194         return result;
 195 }
 196
 197 void pci_dev_assign_slot(struct pci_dev *dev)
 198 {
 199         struct pci_slot *slot;
 200
 201         mutex_lock(&pci_slot_mutex);
 202         list_for_each_entry(slot, &dev->bus->slots, list)
 203                 if (PCI_SLOT(dev->devfn) == slot->number)
 204                         dev->slot = slot;
 205         mutex_unlock(&pci_slot_mutex);
 206 }
 207
 208 static struct pci_slot *get_slot(struct pci_bus *parent, int slot_nr)
 209 {
 210         struct pci_slot *slot;
 211
 212         /* We already hold pci_slot_mutex */
 213         list_for_each_entry(slot, &parent->slots, list)
 214                 if (slot->number == slot_nr) {
 215                         kobject_get(&slot->kobj);
 216                         return slot;
 217                 }
 218
 219         return NULL;
 220 }
 221
 222 /**
 223  * pci_create_slot - create or increment refcount for physical PCI slot
 224  * @parent: struct pci_bus of parent bridge
 225  * @slot_nr: PCI_SLOT(pci_dev->devfn) or -1 for placeholder
 226  * @name: user visible string presented in /sys/bus/pci/slots/<name>
 227  * @hotplug: set if caller is hotplug driver, NULL otherwise
 228  *
 229  * PCI slots have first class attributes such as address, speed, width,
 230  * and a &struct pci_slot is used to manage them. This interface will
 231  * either return a new &struct pci_slot to the caller, or if the pci_slot
 232  * already exists, its refcount will be incremented.
 233  *
 234  * Slots are uniquely identified by a @pci_bus, @slot_nr tuple.
 235  *
 236  * There are known platforms with broken firmware that assign the same
 237  * name to multiple slots. Workaround these broken platforms by renaming
 238  * the slots on behalf of the caller. If firmware assigns name N to
 239  * multiple slots:
 240  *
 241  * The first slot is assigned N
 242  * The second slot is assigned N-1
 243  * The third slot is assigned N-2
 244  * etc.
 245  *
 246  * Placeholder slots:
 247  * In most cases, @pci_bus, @slot_nr will be sufficient to uniquely identify
 248  * a slot. There is one notable exception - pSeries (rpaphp), where the
 249  * @slot_nr cannot be determined until a device is actually inserted into
 250  * the slot. In this scenario, the caller may pass -1 for @slot_nr.
 251  *
 252  * The following semantics are imposed when the caller passes @slot_nr ==
 253  * -1. First, we no longer check for an existing %struct pci_slot, as there
 254  * may be many slots with @slot_nr of -1.  The other change in semantics is
 255  * user-visible, which is the 'address' parameter presented in sysfs will
 256  * consist solely of a dddd:bb tuple, where dddd is the PCI domain of the
 257  * %struct pci_bus and bb is the bus number. In other words, the devfn of
 258  * the 'placeholder' slot will not be displayed.
 259  */
 260 struct pci_slot *pci_create_slot(struct pci_bus *parent, int slot_nr,
 261                                  const char *name,
 262                                  struct hotplug_slot *hotplug)
 263 {
 264         struct pci_dev *dev;
 265         struct pci_slot *slot;
 266         int err = 0;
 267         char *slot_name = NULL;
 268
 269         mutex_lock(&pci_slot_mutex);
 270
 271         if (slot_nr == -1)
 272                 goto placeholder;
 273
 274         /*
 275          * Hotplug drivers are allowed to rename an existing slot,
 276          * but only if not already claimed.
 277          */
 278         slot = get_slot(parent, slot_nr);
 279         if (slot) {
 280                 if (hotplug) {
 281                         if ((err = slot->hotplug ? -EBUSY : 0)
 282                              || (err = rename_slot(slot, name))) {
 283                                 kobject_put(&slot->kobj);
 284                                 slot = NULL;
 285                                 goto err;
 286                         }
 287                 }
 288                 goto out;
 289         }
 290
 291 placeholder:
 292         slot = kzalloc(sizeof(*slot), GFP_KERNEL);
 293         if (!slot) {
 294                 err = -ENOMEM;
 295                 goto err;
 296         }
 297
 298         slot->bus = parent;
 299         slot->number = slot_nr;
 300
 301         slot->kobj.kset = pci_slots_kset;
 302
 303         slot_name = make_slot_name(name);
 304         if (!slot_name) {
 305                 err = -ENOMEM;
 306                 goto err;
 307         }
 308
 309         err = kobject_init_and_add(&slot->kobj, &pci_slot_ktype, NULL,
 310                                    "%s", slot_name);
 311         if (err)
 312                 goto err;
 313
 314         INIT_LIST_HEAD(&slot->list);
 315         list_add(&slot->list, &parent->slots);
 316
 317         down_read(&pci_bus_sem);
 318         list_for_each_entry(dev, &parent->devices, bus_list)
 319                 if (PCI_SLOT(dev->devfn) == slot_nr)
 320                         dev->slot = slot;
 321         up_read(&pci_bus_sem);
 322
 323         dev_dbg(&parent->dev, "dev %02x, created physical slot %s\n",
 324                 slot_nr, pci_slot_name(slot));
 325
 326 out:
 327         kfree(slot_name);
 328         mutex_unlock(&pci_slot_mutex);
 329         return slot;
 330 err:
 331         kfree(slot);
 332         slot = ERR_PTR(err);
 333         goto out;
 334 }
 335 EXPORT_SYMBOL_GPL(pci_create_slot);
 336
 337 /**
 338  * pci_destroy_slot - decrement refcount for physical PCI slot
 339  * @slot: struct pci_slot to decrement
 340  *
 341  * %struct pci_slot is refcounted, so destroying them is really easy; we
 342  * just call kobject_put on its kobj and let our release methods do the
 343  * rest.
 344  */
 345 void pci_destroy_slot(struct pci_slot *slot)
 346 {
 347         dev_dbg(&slot->bus->dev, "dev %02x, dec refcount to %d\n",
 348                 slot->number, kref_read(&slot->kobj.kref) - 1);
 349
 350         mutex_lock(&pci_slot_mutex);
 351         kobject_put(&slot->kobj);
 352         mutex_unlock(&pci_slot_mutex);
 353 }
 354 EXPORT_SYMBOL_GPL(pci_destroy_slot);
 355
 356 #if defined(CONFIG_HOTPLUG_PCI) || defined(CONFIG_HOTPLUG_PCI_MODULE)
 357 #include <linux/pci_hotplug.h>
 358 /**
 359  * pci_hp_create_link - create symbolic link to the hotplug driver module.
 360  * @pci_slot: struct pci_slot
 361  *
 362  * Helper function for pci_hotplug_core.c to create symbolic link to
 363  * the hotplug driver module.
 364  */
 365 void pci_hp_create_module_link(struct pci_slot *pci_slot)
 366 {
 367         struct hotplug_slot *slot = pci_slot->hotplug;
 368         struct kobject *kobj = NULL;
 369         int ret;
 370
 371         if (!slot || !slot->ops)
 372                 return;
 373         kobj = kset_find_obj(module_kset, slot->ops->mod_name);
 374         if (!kobj)
 375                 return;
 376         ret = sysfs_create_link(&pci_slot->kobj, kobj, "module");
 377         if (ret)
 378                 dev_err(&pci_slot->bus->dev, "Error creating sysfs link (%d)\n",
 379                         ret);
 380         kobject_put(kobj);
 381 }
 382 EXPORT_SYMBOL_GPL(pci_hp_create_module_link);
 383
 384 /**
 385  * pci_hp_remove_link - remove symbolic link to the hotplug driver module.
 386  * @pci_slot: struct pci_slot
 387  *
 388  * Helper function for pci_hotplug_core.c to remove symbolic link to
 389  * the hotplug driver module.
 390  */
 391 void pci_hp_remove_module_link(struct pci_slot *pci_slot)
 392 {
 393         sysfs_remove_link(&pci_slot->kobj, "module");
 394 }
 395 EXPORT_SYMBOL_GPL(pci_hp_remove_module_link);
 396 #endif
 397
 398 static int pci_slot_init(void)
 399 {
 400         struct kset *pci_bus_kset;
 401
 402         pci_bus_kset = bus_get_kset(&pci_bus_type);
 403         pci_slots_kset = kset_create_and_add("slots", NULL,
 404                                                 &pci_bus_kset->kobj);
 405         if (!pci_slots_kset) {
 406                 printk(KERN_ERR "PCI: Slot initialization failure\n");
 407                 return -ENOMEM;
 408         }
 409         return 0;
 410 }
 411
 412 subsys_initcall(pci_slot_init);