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_slot *slot = to_pci_slot(kobj);
  53
  54         pr_debug("%s: releasing pci_slot on %x:%d\n", __func__,
  55                  slot->bus->number, slot->number);
  56
  57         list_del(&slot->list);
  58
  59         kfree(slot);
  60 }
  61
  62 static struct pci_slot_attribute pci_slot_attr_address =
  63         __ATTR(address, (S_IFREG | S_IRUGO), address_read_file, NULL);
  64
  65 static struct attribute *pci_slot_default_attrs[] = {
  66         &pci_slot_attr_address.attr,
  67         NULL,
  68 };
  69
  70 static struct kobj_type pci_slot_ktype = {
  71         .sysfs_ops = &pci_slot_sysfs_ops,
  72         .release = &pci_slot_release,
  73         .default_attrs = pci_slot_default_attrs,
  74 };
  75
  76 /**
  77  * pci_create_slot - create or increment refcount for physical PCI slot
  78  * @parent: struct pci_bus of parent bridge
  79  * @slot_nr: PCI_SLOT(pci_dev->devfn) or -1 for placeholder
  80  * @name: user visible string presented in /sys/bus/pci/slots/<name>
  81  *
  82  * PCI slots have first class attributes such as address, speed, width,
  83  * and a &struct pci_slot is used to manage them. This interface will
  84  * either return a new &struct pci_slot to the caller, or if the pci_slot
  85  * already exists, its refcount will be incremented.
  86  *
  87  * Slots are uniquely identified by a @pci_bus, @slot_nr, @name tuple.
  88  *
  89  * Placeholder slots:
  90  * In most cases, @pci_bus, @slot_nr will be sufficient to uniquely identify
  91  * a slot. There is one notable exception - pSeries (rpaphp), where the
  92  * @slot_nr cannot be determined until a device is actually inserted into
  93  * the slot. In this scenario, the caller may pass -1 for @slot_nr.
  94  *
  95  * The following semantics are imposed when the caller passes @slot_nr ==
  96  * -1. First, the check for existing %struct pci_slot is skipped, as the
  97  * caller may know about several unpopulated slots on a given %struct
  98  * pci_bus, and each slot would have a @slot_nr of -1.  Uniqueness for
  99  * these slots is then determined by the @name parameter. We expect
 100  * kobject_init_and_add() to warn us if the caller attempts to create
 101  * multiple slots with the same name. The other change in semantics is
 102  * user-visible, which is the 'address' parameter presented in sysfs will
 103  * consist solely of a dddd:bb tuple, where dddd is the PCI domain of the
 104  * %struct pci_bus and bb is the bus number. In other words, the devfn of
 105  * the 'placeholder' slot will not be displayed.
 106  */
 107
 108 struct pci_slot *pci_create_slot(struct pci_bus *parent, int slot_nr,
 109                                  const char *name)
 110 {
 111         struct pci_slot *slot;
 112         int err;
 113
 114         down_write(&pci_bus_sem);
 115
 116         if (slot_nr == -1)
 117                 goto placeholder;
 118
 119         /* If we've already created this slot, bump refcount and return. */
 120         list_for_each_entry(slot, &parent->slots, list) {
 121                 if (slot->number == slot_nr) {
 122                         kobject_get(&slot->kobj);
 123                         pr_debug("%s: inc refcount to %d on %04x:%02x:%02x\n",
 124                                  __func__,
 125                                  atomic_read(&slot->kobj.kref.refcount),
 126                                  pci_domain_nr(parent), parent->number,
 127                                  slot_nr);
 128                         goto out;
 129                 }
 130         }
 131
 132 placeholder:
 133         slot = kzalloc(sizeof(*slot), GFP_KERNEL);
 134         if (!slot) {
 135                 slot = ERR_PTR(-ENOMEM);
 136                 goto out;
 137         }
 138
 139         slot->bus = parent;
 140         slot->number = slot_nr;
 141
 142         slot->kobj.kset = pci_slots_kset;
 143         err = kobject_init_and_add(&slot->kobj, &pci_slot_ktype, NULL,
 144                                    "%s", name);
 145         if (err) {
 146                 printk(KERN_ERR "Unable to register kobject %s\n", name);
 147                 goto err;
 148         }
 149
 150         INIT_LIST_HEAD(&slot->list);
 151         list_add(&slot->list, &parent->slots);
 152
 153         /* Don't care if debug printk has a -1 for slot_nr */
 154         pr_debug("%s: created pci_slot on %04x:%02x:%02x\n",
 155                  __func__, pci_domain_nr(parent), parent->number, slot_nr);
 156
 157  out:
 158         up_write(&pci_bus_sem);
 159         return slot;
 160  err:
 161         kfree(slot);
 162         slot = ERR_PTR(err);
 163         goto out;
 164 }
 165 EXPORT_SYMBOL_GPL(pci_create_slot);
 166
 167 /**
 168  * pci_update_slot_number - update %struct pci_slot -> number
 169  * @slot - %struct pci_slot to update
 170  * @slot_nr - new number for slot
 171  *
 172  * The primary purpose of this interface is to allow callers who earlier
 173  * created a placeholder slot in pci_create_slot() by passing a -1 as
 174  * slot_nr, to update their %struct pci_slot with the correct @slot_nr.
 175  */
 176
 177 void pci_update_slot_number(struct pci_slot *slot, int slot_nr)
 178 {
 179         int name_count = 0;
 180         struct pci_slot *tmp;
 181
 182         down_write(&pci_bus_sem);
 183
 184         list_for_each_entry(tmp, &slot->bus->slots, list) {
 185                 WARN_ON(tmp->number == slot_nr);
 186                 if (!strcmp(kobject_name(&tmp->kobj), kobject_name(&slot->kobj)))
 187                         name_count++;
 188         }
 189
 190         if (name_count > 1)
 191                 printk(KERN_WARNING "pci_update_slot_number found %d slots with the same name: %s\n", name_count, kobject_name(&slot->kobj));
 192
 193         slot->number = slot_nr;
 194         up_write(&pci_bus_sem);
 195 }
 196 EXPORT_SYMBOL_GPL(pci_update_slot_number);
 197
 198 /**
 199  * pci_destroy_slot - decrement refcount for physical PCI slot
 200  * @slot: struct pci_slot to decrement
 201  *
 202  * %struct pci_slot is refcounted, so destroying them is really easy; we
 203  * just call kobject_put on its kobj and let our release methods do the
 204  * rest.
 205  */
 206
 207 void pci_destroy_slot(struct pci_slot *slot)
 208 {
 209         pr_debug("%s: dec refcount to %d on %04x:%02x:%02x\n", __func__,
 210                  atomic_read(&slot->kobj.kref.refcount) - 1,
 211                  pci_domain_nr(slot->bus), slot->bus->number, slot->number);
 212
 213         down_write(&pci_bus_sem);
 214         kobject_put(&slot->kobj);
 215         up_write(&pci_bus_sem);
 216 }
 217 EXPORT_SYMBOL_GPL(pci_destroy_slot);
 218
 219 static int pci_slot_init(void)
 220 {
 221         struct kset *pci_bus_kset;
 222
 223         pci_bus_kset = bus_get_kset(&pci_bus_type);
 224         pci_slots_kset = kset_create_and_add("slots", NULL,
 225                                                 &pci_bus_kset->kobj);
 226         if (!pci_slots_kset) {
 227                 printk(KERN_ERR "PCI: Slot initialization failure\n");
 228                 return -ENOMEM;
 229         }
 230         return 0;
 231 }
 232
 233 subsys_initcall(pci_slot_init);