drivers/pci/slot.c

   1 /*
   2  * drivers/pci/slot.c
   3  * Copyright (C) 2006 Matthew Wilcox <matthew@wil.cx>
   4  * Copyright (C) 2006-2008 Hewlett-Packard Development Company, L.P.
   5  *      Alex Chiang <achiang@hp.com>
   6  */
   7
   8 #include <linux/kobject.h>
   9 #include <linux/pci.h>
  10 #include <linux/err.h>
  11 #include "pci.h"
  12
  13 struct kset *pci_slots_kset;
  14 EXPORT_SYMBOL_GPL(pci_slots_kset);
  15
  16 static ssize_t pci_slot_attr_show(struct kobject *kobj,
  17                                         struct attribute *attr, char *buf)
  18 {
  19         struct pci_slot *slot = to_pci_slot(kobj);
  20         struct pci_slot_attribute *attribute = to_pci_slot_attr(attr);
  21         return attribute->show ? attribute->show(slot, buf) : -EIO;
  22 }
  23
  24 static ssize_t pci_slot_attr_store(struct kobject *kobj,
  25                         struct attribute *attr, const char *buf, size_t len)
  26 {
  27         struct pci_slot *slot = to_pci_slot(kobj);
  28         struct pci_slot_attribute *attribute = to_pci_slot_attr(attr);
  29         return attribute->store ? attribute->store(slot, buf, len) : -EIO;
  30 }
  31
  32 static struct sysfs_ops pci_slot_sysfs_ops = {
  33         .show = pci_slot_attr_show,
  34         .store = pci_slot_attr_store,
  35 };
  36
  37 static ssize_t address_read_file(struct pci_slot *slot, char *buf)
  38 {
  39         if (slot->number == 0xff)
  40                 return sprintf(buf, "%04x:%02x\n",
  41                                 pci_domain_nr(slot->bus),
  42                                 slot->bus->number);
  43         else
  44                 return sprintf(buf, "%04x:%02x:%02x\n",
  45                                 pci_domain_nr(slot->bus),
  46                                 slot->bus->number,
  47                                 slot->number);
  48 }
  49
  50 static void pci_slot_release(struct kobject *kobj)
  51 {
  52         struct pci_dev *dev;
  53         struct pci_slot *slot = to_pci_slot(kobj);
  54
  55         pr_debug("%s: releasing pci_slot on %x:%d\n", __func__,
  56                  slot->bus->number, slot->number);
  57
  58         list_for_each_entry(dev, &slot->bus->devices, bus_list)
  59                 if (PCI_SLOT(dev->devfn) == slot->number)
  60                         dev->slot = NULL;
  61
  62         list_del(&slot->list);
  63
  64         kfree(slot);
  65 }
  66
  67 static struct pci_slot_attribute pci_slot_attr_address =
  68         __ATTR(address, (S_IFREG | S_IRUGO), address_read_file, NULL);
  69
  70 static struct attribute *pci_slot_default_attrs[] = {
  71         &pci_slot_attr_address.attr,
  72         NULL,
  73 };
  74
  75 static struct kobj_type pci_slot_ktype = {
  76         .sysfs_ops = &pci_slot_sysfs_ops,
  77         .release = &pci_slot_release,
  78         .default_attrs = pci_slot_default_attrs,
  79 };
  80
  81 static char *make_slot_name(const char *name)
  82 {
  83         char *new_name;
  84         int len, max, dup;
  85
  86         new_name = kstrdup(name, GFP_KERNEL);
  87         if (!new_name)
  88                 return NULL;
  89
  90         /*
  91          * Make sure we hit the realloc case the first time through the
  92          * loop.  'len' will be strlen(name) + 3 at that point which is
  93          * enough space for "name-X" and the trailing NUL.
  94          */
  95         len = strlen(name) + 2;
  96         max = 1;
  97         dup = 1;
  98
  99         for (;;) {
 100                 struct kobject *dup_slot;
 101                 dup_slot = kset_find_obj(pci_slots_kset, new_name);
 102                 if (!dup_slot)
 103                         break;
 104                 kobject_put(dup_slot);
 105                 if (dup == max) {
 106                         len++;
 107                         max *= 10;
 108                         kfree(new_name);
 109                         new_name = kmalloc(len, GFP_KERNEL);
 110                         if (!new_name)
 111                                 break;
 112                 }
 113                 sprintf(new_name, "%s-%d", name, dup++);
 114         }
 115
 116         return new_name;
 117 }
 118
 119 static int rename_slot(struct pci_slot *slot, const char *name)
 120 {
 121         int result = 0;
 122         char *slot_name;
 123
 124         if (strcmp(pci_slot_name(slot), name) == 0)
 125                 return result;
 126
 127         slot_name = make_slot_name(name);
 128         if (!slot_name)
 129                 return -ENOMEM;
 130
 131         result = kobject_rename(&slot->kobj, slot_name);
 132         kfree(slot_name);
 133
 134         return result;
 135 }
 136
 137 static struct pci_slot *get_slot(struct pci_bus *parent, int slot_nr)
 138 {
 139         struct pci_slot *slot;
 140         /*
 141          * We already hold pci_bus_sem so don't worry
 142          */
 143         list_for_each_entry(slot, &parent->slots, list)
 144                 if (slot->number == slot_nr) {
 145                         kobject_get(&slot->kobj);
 146                         return slot;
 147                 }
 148
 149         return NULL;
 150 }
 151
 152 /**
 153  * pci_create_slot - create or increment refcount for physical PCI slot
 154  * @parent: struct pci_bus of parent bridge
 155  * @slot_nr: PCI_SLOT(pci_dev->devfn) or -1 for placeholder
 156  * @name: user visible string presented in /sys/bus/pci/slots/<name>
 157  * @hotplug: set if caller is hotplug driver, NULL otherwise
 158  *
 159  * PCI slots have first class attributes such as address, speed, width,
 160  * and a &struct pci_slot is used to manage them. This interface will
 161  * either return a new &struct pci_slot to the caller, or if the pci_slot
 162  * already exists, its refcount will be incremented.
 163  *
 164  * Slots are uniquely identified by a @pci_bus, @slot_nr tuple.
 165  *
 166  * There are known platforms with broken firmware that assign the same
 167  * name to multiple slots. Workaround these broken platforms by renaming
 168  * the slots on behalf of the caller. If firmware assigns name N to
 169  * multiple slots:
 170  *
 171  * The first slot is assigned N
 172  * The second slot is assigned N-1
 173  * The third slot is assigned N-2
 174  * etc.
 175  *
 176  * Placeholder slots:
 177  * In most cases, @pci_bus, @slot_nr will be sufficient to uniquely identify
 178  * a slot. There is one notable exception - pSeries (rpaphp), where the
 179  * @slot_nr cannot be determined until a device is actually inserted into
 180  * the slot. In this scenario, the caller may pass -1 for @slot_nr.
 181  *
 182  * The following semantics are imposed when the caller passes @slot_nr ==
 183  * -1. First, we no longer check for an existing %struct pci_slot, as there
 184  * may be many slots with @slot_nr of -1.  The other change in semantics is
 185  * user-visible, which is the 'address' parameter presented in sysfs will
 186  * consist solely of a dddd:bb tuple, where dddd is the PCI domain of the
 187  * %struct pci_bus and bb is the bus number. In other words, the devfn of
 188  * the 'placeholder' slot will not be displayed.
 189  */
 190 struct pci_slot *pci_create_slot(struct pci_bus *parent, int slot_nr,
 191                                  const char *name,
 192                                  struct hotplug_slot *hotplug)
 193 {
 194         struct pci_dev *dev;
 195         struct pci_slot *slot;
 196         int err = 0;
 197         char *slot_name = NULL;
 198
 199         down_write(&pci_bus_sem);
 200
 201         if (slot_nr == -1)
 202                 goto placeholder;
 203
 204         /*
 205          * Hotplug drivers are allowed to rename an existing slot,
 206          * but only if not already claimed.
 207          */
 208         slot = get_slot(parent, slot_nr);
 209         if (slot) {
 210                 if (hotplug) {
 211                         if ((err = slot->hotplug ? -EBUSY : 0)
 212                              || (err = rename_slot(slot, name))) {
 213                                 kobject_put(&slot->kobj);
 214                                 slot = NULL;
 215                                 goto err;
 216                         }
 217                 }
 218                 goto out;
 219         }
 220
 221 placeholder:
 222         slot = kzalloc(sizeof(*slot), GFP_KERNEL);
 223         if (!slot) {
 224                 err = -ENOMEM;
 225                 goto err;
 226         }
 227
 228         slot->bus = parent;
 229         slot->number = slot_nr;
 230
 231         slot->kobj.kset = pci_slots_kset;
 232
 233         slot_name = make_slot_name(name);
 234         if (!slot_name) {
 235                 err = -ENOMEM;
 236                 goto err;
 237         }
 238
 239         err = kobject_init_and_add(&slot->kobj, &pci_slot_ktype, NULL,
 240                                    "%s", slot_name);
 241         if (err)
 242                 goto err;
 243
 244         INIT_LIST_HEAD(&slot->list);
 245         list_add(&slot->list, &parent->slots);
 246
 247         list_for_each_entry(dev, &parent->devices, bus_list)
 248                 if (PCI_SLOT(dev->devfn) == slot_nr)
 249                         dev->slot = slot;
 250
 251         /* Don't care if debug printk has a -1 for slot_nr */
 252         pr_debug("%s: created pci_slot on %04x:%02x:%02x\n",
 253                  __func__, pci_domain_nr(parent), parent->number, slot_nr);
 254
 255 out:
 256         kfree(slot_name);
 257         up_write(&pci_bus_sem);
 258         return slot;
 259 err:
 260         kfree(slot);
 261         slot = ERR_PTR(err);
 262         goto out;
 263 }
 264 EXPORT_SYMBOL_GPL(pci_create_slot);
 265
 266 /**
 267  * pci_renumber_slot - update %struct pci_slot -> number
 268  * @slot - %struct pci_slot to update
 269  * @slot_nr - new number for slot
 270  *
 271  * The primary purpose of this interface is to allow callers who earlier
 272  * created a placeholder slot in pci_create_slot() by passing a -1 as
 273  * slot_nr, to update their %struct pci_slot with the correct @slot_nr.
 274  */
 275 void pci_renumber_slot(struct pci_slot *slot, int slot_nr)
 276 {
 277         struct pci_slot *tmp;
 278
 279         down_write(&pci_bus_sem);
 280
 281         list_for_each_entry(tmp, &slot->bus->slots, list) {
 282                 WARN_ON(tmp->number == slot_nr);
 283                 goto out;
 284         }
 285
 286         slot->number = slot_nr;
 287 out:
 288         up_write(&pci_bus_sem);
 289 }
 290 EXPORT_SYMBOL_GPL(pci_renumber_slot);
 291
 292 /**
 293  * pci_destroy_slot - decrement refcount for physical PCI slot
 294  * @slot: struct pci_slot to decrement
 295  *
 296  * %struct pci_slot is refcounted, so destroying them is really easy; we
 297  * just call kobject_put on its kobj and let our release methods do the
 298  * rest.
 299  */
 300 void pci_destroy_slot(struct pci_slot *slot)
 301 {
 302         pr_debug("%s: dec refcount to %d on %04x:%02x:%02x\n", __func__,
 303                  atomic_read(&slot->kobj.kref.refcount) - 1,
 304                  pci_domain_nr(slot->bus), slot->bus->number, slot->number);
 305
 306         down_write(&pci_bus_sem);
 307         kobject_put(&slot->kobj);
 308         up_write(&pci_bus_sem);
 309 }
 310 EXPORT_SYMBOL_GPL(pci_destroy_slot);
 311
 312 static int pci_slot_init(void)
 313 {
 314         struct kset *pci_bus_kset;
 315
 316         pci_bus_kset = bus_get_kset(&pci_bus_type);
 317         pci_slots_kset = kset_create_and_add("slots", NULL,
 318                                                 &pci_bus_kset->kobj);
 319         if (!pci_slots_kset) {
 320                 printk(KERN_ERR "PCI: Slot initialization failure\n");
 321                 return -ENOMEM;
 322         }
 323         return 0;
 324 }
 325
 326 subsys_initcall(pci_slot_init);