drivers/pci/slot.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * drivers/pci/slot.c
   4  * Copyright (C) 2006 Matthew Wilcox <matthew@wil.cx>
   5  * Copyright (C) 2006-2009 Hewlett-Packard Development Company, L.P.
   6  *      Alex Chiang <achiang@hp.com>
   7  */
   8
   9 #include <linux/kobject.h>
  10 #include <linux/slab.h>
  11 #include <linux/module.h>
  12 #include <linux/pci.h>
  13 #include <linux/err.h>
  14 #include "pci.h"
  15
  16 struct kset *pci_slots_kset;
  17 EXPORT_SYMBOL_GPL(pci_slots_kset);
  18 static DEFINE_MUTEX(pci_slot_mutex);
  19
  20 static ssize_t pci_slot_attr_show(struct kobject *kobj,
  21                                         struct attribute *attr, char *buf)
  22 {
  23         struct pci_slot *slot = to_pci_slot(kobj);
  24         struct pci_slot_attribute *attribute = to_pci_slot_attr(attr);
  25         return attribute->show ? attribute->show(slot, buf) : -EIO;
  26 }
  27
  28 static ssize_t pci_slot_attr_store(struct kobject *kobj,
  29                         struct attribute *attr, const char *buf, size_t len)
  30 {
  31         struct pci_slot *slot = to_pci_slot(kobj);
  32         struct pci_slot_attribute *attribute = to_pci_slot_attr(attr);
  33         return attribute->store ? attribute->store(slot, buf, len) : -EIO;
  34 }
  35
  36 static const struct sysfs_ops pci_slot_sysfs_ops = {
  37         .show = pci_slot_attr_show,
  38         .store = pci_slot_attr_store,
  39 };
  40
  41 static ssize_t address_read_file(struct pci_slot *slot, char *buf)
  42 {
  43         if (slot->number == 0xff)
  44                 return sprintf(buf, "%04x:%02x\n",
  45                                 pci_domain_nr(slot->bus),
  46                                 slot->bus->number);
  47         else
  48                 return sprintf(buf, "%04x:%02x:%02x\n",
  49                                 pci_domain_nr(slot->bus),
  50                                 slot->bus->number,
  51                                 slot->number);
  52 }
  53
  54 /* these strings match up with the values in pci_bus_speed */
  55 static const char *pci_bus_speed_strings[] = {
  56         "33 MHz PCI",           /* 0x00 */
  57         "66 MHz PCI",           /* 0x01 */
  58         "66 MHz PCI-X",         /* 0x02 */
  59         "100 MHz PCI-X",        /* 0x03 */
  60         "133 MHz PCI-X",        /* 0x04 */
  61         NULL,                   /* 0x05 */
  62         NULL,                   /* 0x06 */
  63         NULL,                   /* 0x07 */
  64         NULL,                   /* 0x08 */
  65         "66 MHz PCI-X 266",     /* 0x09 */
  66         "100 MHz PCI-X 266",    /* 0x0a */
  67         "133 MHz PCI-X 266",    /* 0x0b */
  68         "Unknown AGP",          /* 0x0c */
  69         "1x AGP",               /* 0x0d */
  70         "2x AGP",               /* 0x0e */
  71         "4x AGP",               /* 0x0f */
  72         "8x AGP",               /* 0x10 */
  73         "66 MHz PCI-X 533",     /* 0x11 */
  74         "100 MHz PCI-X 533",    /* 0x12 */
  75         "133 MHz PCI-X 533",    /* 0x13 */
  76         "2.5 GT/s PCIe",        /* 0x14 */
  77         "5.0 GT/s PCIe",        /* 0x15 */
  78         "8.0 GT/s PCIe",        /* 0x16 */
  79 };
  80
  81 static ssize_t bus_speed_read(enum pci_bus_speed speed, char *buf)
  82 {
  83         const char *speed_string;
  84
  85         if (speed < ARRAY_SIZE(pci_bus_speed_strings))
  86                 speed_string = pci_bus_speed_strings[speed];
  87         else
  88                 speed_string = "Unknown";
  89
  90         return sprintf(buf, "%s\n", speed_string);
  91 }
  92
  93 static ssize_t max_speed_read_file(struct pci_slot *slot, char *buf)
  94 {
  95         return bus_speed_read(slot->bus->max_bus_speed, buf);
  96 }
  97
  98 static ssize_t cur_speed_read_file(struct pci_slot *slot, char *buf)
  99 {
 100         return bus_speed_read(slot->bus->cur_bus_speed, buf);
 101 }
 102
 103 static void pci_slot_release(struct kobject *kobj)
 104 {
 105         struct pci_dev *dev;
 106         struct pci_slot *slot = to_pci_slot(kobj);
 107
 108         dev_dbg(&slot->bus->dev, "dev %02x, released physical slot %s\n",
 109                 slot->number, pci_slot_name(slot));
 110
 111         down_read(&pci_bus_sem);
 112         list_for_each_entry(dev, &slot->bus->devices, bus_list)
 113                 if (PCI_SLOT(dev->devfn) == slot->number)
 114                         dev->slot = NULL;
 115         up_read(&pci_bus_sem);
 116
 117         list_del(&slot->list);
 118
 119         kfree(slot);
 120 }
 121
 122 static struct pci_slot_attribute pci_slot_attr_address =
 123         __ATTR(address, S_IRUGO, address_read_file, NULL);
 124 static struct pci_slot_attribute pci_slot_attr_max_speed =
 125         __ATTR(max_bus_speed, S_IRUGO, max_speed_read_file, NULL);
 126 static struct pci_slot_attribute pci_slot_attr_cur_speed =
 127         __ATTR(cur_bus_speed, S_IRUGO, cur_speed_read_file, NULL);
 128
 129 static struct attribute *pci_slot_default_attrs[] = {
 130         &pci_slot_attr_address.attr,
 131         &pci_slot_attr_max_speed.attr,
 132         &pci_slot_attr_cur_speed.attr,
 133         NULL,
 134 };
 135
 136 static struct kobj_type pci_slot_ktype = {
 137         .sysfs_ops = &pci_slot_sysfs_ops,
 138         .release = &pci_slot_release,
 139         .default_attrs = pci_slot_default_attrs,
 140 };
 141
 142 static char *make_slot_name(const char *name)
 143 {
 144         char *new_name;
 145         int len, max, dup;
 146
 147         new_name = kstrdup(name, GFP_KERNEL);
 148         if (!new_name)
 149                 return NULL;
 150
 151         /*
 152          * Make sure we hit the realloc case the first time through the
 153          * loop.  'len' will be strlen(name) + 3 at that point which is
 154          * enough space for "name-X" and the trailing NUL.
 155          */
 156         len = strlen(name) + 2;
 157         max = 1;
 158         dup = 1;
 159
 160         for (;;) {
 161                 struct kobject *dup_slot;
 162                 dup_slot = kset_find_obj(pci_slots_kset, new_name);
 163                 if (!dup_slot)
 164                         break;
 165                 kobject_put(dup_slot);
 166                 if (dup == max) {
 167                         len++;
 168                         max *= 10;
 169                         kfree(new_name);
 170                         new_name = kmalloc(len, GFP_KERNEL);
 171                         if (!new_name)
 172                                 break;
 173                 }
 174                 sprintf(new_name, "%s-%d", name, dup++);
 175         }
 176
 177         return new_name;
 178 }
 179
 180 static int rename_slot(struct pci_slot *slot, const char *name)
 181 {
 182         int result = 0;
 183         char *slot_name;
 184
 185         if (strcmp(pci_slot_name(slot), name) == 0)
 186                 return result;
 187
 188         slot_name = make_slot_name(name);
 189         if (!slot_name)
 190                 return -ENOMEM;
 191
 192         result = kobject_rename(&slot->kobj, slot_name);
 193         kfree(slot_name);
 194
 195         return result;
 196 }
 197
 198 void pci_dev_assign_slot(struct pci_dev *dev)
 199 {
 200         struct pci_slot *slot;
 201
 202         mutex_lock(&pci_slot_mutex);
 203         list_for_each_entry(slot, &dev->bus->slots, list)
 204                 if (PCI_SLOT(dev->devfn) == slot->number)
 205                         dev->slot = slot;
 206         mutex_unlock(&pci_slot_mutex);
 207 }
 208
 209 static struct pci_slot *get_slot(struct pci_bus *parent, int slot_nr)
 210 {
 211         struct pci_slot *slot;
 212
 213         /* We already hold pci_slot_mutex */
 214         list_for_each_entry(slot, &parent->slots, list)
 215                 if (slot->number == slot_nr) {
 216                         kobject_get(&slot->kobj);
 217                         return slot;
 218                 }
 219
 220         return NULL;
 221 }
 222
 223 /**
 224  * pci_create_slot - create or increment refcount for physical PCI slot
 225  * @parent: struct pci_bus of parent bridge
 226  * @slot_nr: PCI_SLOT(pci_dev->devfn) or -1 for placeholder
 227  * @name: user visible string presented in /sys/bus/pci/slots/<name>
 228  * @hotplug: set if caller is hotplug driver, NULL otherwise
 229  *
 230  * PCI slots have first class attributes such as address, speed, width,
 231  * and a &struct pci_slot is used to manage them. This interface will
 232  * either return a new &struct pci_slot to the caller, or if the pci_slot
 233  * already exists, its refcount will be incremented.
 234  *
 235  * Slots are uniquely identified by a @pci_bus, @slot_nr tuple.
 236  *
 237  * There are known platforms with broken firmware that assign the same
 238  * name to multiple slots. Workaround these broken platforms by renaming
 239  * the slots on behalf of the caller. If firmware assigns name N to
 240  * multiple slots:
 241  *
 242  * The first slot is assigned N
 243  * The second slot is assigned N-1
 244  * The third slot is assigned N-2
 245  * etc.
 246  *
 247  * Placeholder slots:
 248  * In most cases, @pci_bus, @slot_nr will be sufficient to uniquely identify
 249  * a slot. There is one notable exception - pSeries (rpaphp), where the
 250  * @slot_nr cannot be determined until a device is actually inserted into
 251  * the slot. In this scenario, the caller may pass -1 for @slot_nr.
 252  *
 253  * The following semantics are imposed when the caller passes @slot_nr ==
 254  * -1. First, we no longer check for an existing %struct pci_slot, as there
 255  * may be many slots with @slot_nr of -1.  The other change in semantics is
 256  * user-visible, which is the 'address' parameter presented in sysfs will
 257  * consist solely of a dddd:bb tuple, where dddd is the PCI domain of the
 258  * %struct pci_bus and bb is the bus number. In other words, the devfn of
 259  * the 'placeholder' slot will not be displayed.
 260  */
 261 struct pci_slot *pci_create_slot(struct pci_bus *parent, int slot_nr,
 262                                  const char *name,
 263                                  struct hotplug_slot *hotplug)
 264 {
 265         struct pci_dev *dev;
 266         struct pci_slot *slot;
 267         int err = 0;
 268         char *slot_name = NULL;
 269
 270         mutex_lock(&pci_slot_mutex);
 271
 272         if (slot_nr == -1)
 273                 goto placeholder;
 274
 275         /*
 276          * Hotplug drivers are allowed to rename an existing slot,
 277          * but only if not already claimed.
 278          */
 279         slot = get_slot(parent, slot_nr);
 280         if (slot) {
 281                 if (hotplug) {
 282                         if ((err = slot->hotplug ? -EBUSY : 0)
 283                              || (err = rename_slot(slot, name))) {
 284                                 kobject_put(&slot->kobj);
 285                                 slot = NULL;
 286                                 goto err;
 287                         }
 288                 }
 289                 goto out;
 290         }
 291
 292 placeholder:
 293         slot = kzalloc(sizeof(*slot), GFP_KERNEL);
 294         if (!slot) {
 295                 err = -ENOMEM;
 296                 goto err;
 297         }
 298
 299         slot->bus = parent;
 300         slot->number = slot_nr;
 301
 302         slot->kobj.kset = pci_slots_kset;
 303
 304         slot_name = make_slot_name(name);
 305         if (!slot_name) {
 306                 err = -ENOMEM;
 307                 goto err;
 308         }
 309
 310         err = kobject_init_and_add(&slot->kobj, &pci_slot_ktype, NULL,
 311                                    "%s", slot_name);
 312         if (err)
 313                 goto err;
 314
 315         INIT_LIST_HEAD(&slot->list);
 316         list_add(&slot->list, &parent->slots);
 317
 318         down_read(&pci_bus_sem);
 319         list_for_each_entry(dev, &parent->devices, bus_list)
 320                 if (PCI_SLOT(dev->devfn) == slot_nr)
 321                         dev->slot = slot;
 322         up_read(&pci_bus_sem);
 323
 324         dev_dbg(&parent->dev, "dev %02x, created physical slot %s\n",
 325                 slot_nr, pci_slot_name(slot));
 326
 327 out:
 328         kfree(slot_name);
 329         mutex_unlock(&pci_slot_mutex);
 330         return slot;
 331 err:
 332         kfree(slot);
 333         slot = ERR_PTR(err);
 334         goto out;
 335 }
 336 EXPORT_SYMBOL_GPL(pci_create_slot);
 337
 338 /**
 339  * pci_destroy_slot - decrement refcount for physical PCI slot
 340  * @slot: struct pci_slot to decrement
 341  *
 342  * %struct pci_slot is refcounted, so destroying them is really easy; we
 343  * just call kobject_put on its kobj and let our release methods do the
 344  * rest.
 345  */
 346 void pci_destroy_slot(struct pci_slot *slot)
 347 {
 348         dev_dbg(&slot->bus->dev, "dev %02x, dec refcount to %d\n",
 349                 slot->number, kref_read(&slot->kobj.kref) - 1);
 350
 351         mutex_lock(&pci_slot_mutex);
 352         kobject_put(&slot->kobj);
 353         mutex_unlock(&pci_slot_mutex);
 354 }
 355 EXPORT_SYMBOL_GPL(pci_destroy_slot);
 356
 357 #if defined(CONFIG_HOTPLUG_PCI) || defined(CONFIG_HOTPLUG_PCI_MODULE)
 358 #include <linux/pci_hotplug.h>
 359 /**
 360  * pci_hp_create_link - create symbolic link to the hotplug driver module.
 361  * @pci_slot: struct pci_slot
 362  *
 363  * Helper function for pci_hotplug_core.c to create symbolic link to
 364  * the hotplug driver module.
 365  */
 366 void pci_hp_create_module_link(struct pci_slot *pci_slot)
 367 {
 368         struct hotplug_slot *slot = pci_slot->hotplug;
 369         struct kobject *kobj = NULL;
 370         int ret;
 371
 372         if (!slot || !slot->ops)
 373                 return;
 374         kobj = kset_find_obj(module_kset, slot->ops->mod_name);
 375         if (!kobj)
 376                 return;
 377         ret = sysfs_create_link(&pci_slot->kobj, kobj, "module");
 378         if (ret)
 379                 dev_err(&pci_slot->bus->dev, "Error creating sysfs link (%d)\n",
 380                         ret);
 381         kobject_put(kobj);
 382 }
 383 EXPORT_SYMBOL_GPL(pci_hp_create_module_link);
 384
 385 /**
 386  * pci_hp_remove_link - remove symbolic link to the hotplug driver module.
 387  * @pci_slot: struct pci_slot
 388  *
 389  * Helper function for pci_hotplug_core.c to remove symbolic link to
 390  * the hotplug driver module.
 391  */
 392 void pci_hp_remove_module_link(struct pci_slot *pci_slot)
 393 {
 394         sysfs_remove_link(&pci_slot->kobj, "module");
 395 }
 396 EXPORT_SYMBOL_GPL(pci_hp_remove_module_link);
 397 #endif
 398
 399 static int pci_slot_init(void)
 400 {
 401         struct kset *pci_bus_kset;
 402
 403         pci_bus_kset = bus_get_kset(&pci_bus_type);
 404         pci_slots_kset = kset_create_and_add("slots", NULL,
 405                                                 &pci_bus_kset->kobj);
 406         if (!pci_slots_kset) {
 407                 printk(KERN_ERR "PCI: Slot initialization failure\n");
 408                 return -ENOMEM;
 409         }
 410         return 0;
 411 }
 412
 413 subsys_initcall(pci_slot_init);