linux/drivers/pci/slot.c
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   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
  15struct kset *pci_slots_kset;
  16EXPORT_SYMBOL_GPL(pci_slots_kset);
  17
  18static 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
  26static 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
  34static const struct sysfs_ops pci_slot_sysfs_ops = {
  35        .show = pci_slot_attr_show,
  36        .store = pci_slot_attr_store,
  37};
  38
  39static 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
  52static ssize_t bus_speed_read(enum pci_bus_speed speed, char *buf)
  53{
  54        return sprintf(buf, "%s\n", pci_speed_string(speed));
  55}
  56
  57static 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
  62static 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
  67static 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
  86static struct pci_slot_attribute pci_slot_attr_address =
  87        __ATTR(address, S_IRUGO, address_read_file, NULL);
  88static struct pci_slot_attribute pci_slot_attr_max_speed =
  89        __ATTR(max_bus_speed, S_IRUGO, max_speed_read_file, NULL);
  90static struct pci_slot_attribute pci_slot_attr_cur_speed =
  91        __ATTR(cur_bus_speed, S_IRUGO, cur_speed_read_file, NULL);
  92
  93static 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
 100static 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
 106static 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
 144static 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
 162void 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
 173static 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 */
 225struct 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
 256placeholder:
 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
 294out:
 295        kfree(slot_name);
 296        mutex_unlock(&pci_slot_mutex);
 297        return slot;
 298err:
 299        slot = ERR_PTR(err);
 300        goto out;
 301}
 302EXPORT_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 */
 312void 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}
 321EXPORT_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 */
 332void 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}
 349EXPORT_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 */
 359void pci_hp_remove_module_link(struct pci_slot *pci_slot)
 360{
 361        sysfs_remove_link(&pci_slot->kobj, "module");
 362}
 363EXPORT_SYMBOL_GPL(pci_hp_remove_module_link);
 364#endif
 365
 366static 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
 380subsys_initcall(pci_slot_init);
 381