PCI: introduce pci_slot

Currently, /sys/bus/pci/slots/ only exposes hotplug attributes when a
hotplug driver is loaded, but PCI slots have attributes such as address,
speed, width, etc.  that are not related to hotplug at all.

Introduce pci_slot as the primary data structure and kobject model.
Hotplug attributes described in hotplug_slot become a secondary
structure associated with the pci_slot.

This patch only creates the infrastructure that allows the separation of
PCI slot attributes and hotplug attributes.  In this patch, the PCI
hotplug core remains the only user of this infrastructure, and thus,
/sys/bus/pci/slots/ will still only become populated when a hotplug
driver is loaded.

A later patch in this series will add a second user of this new
infrastructure and demonstrate splitting the task of exposing pci_slot
attributes from hotplug_slot attributes.

  - Make pci_slot the primary sysfs entity. hotplug_slot becomes a
    subsidiary structure.
    o pci_create_slot() creates and registers a slot with the PCI core
    o pci_slot_add_hotplug() gives it hotplug capability

  - Change the prototype of pci_hp_register() to take the bus and
    slot number (on parent bus) as parameters.

  - Remove all the ->get_address methods since this functionality is
    now handled by pci_slot directly.

[achiang@hp.com: rpaphp-correctly-pci_hp_register-for-empty-pci-slots]
Tested-by: Badari Pulavarty <pbadari@us.ibm.com>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
[akpm@linux-foundation.org: build fix]
[akpm@linux-foundation.org: make headers_check happy]
[akpm@linux-foundation.org: nuther build fix]
[akpm@linux-foundation.org: fix typo in #include]
Signed-off-by: Alex Chiang <achiang@hp.com>
Signed-off-by: Matthew Wilcox <matthew@wil.cx>
Cc: Greg KH <greg@kroah.com>
Cc: Kristen Carlson Accardi <kristen.c.accardi@intel.com>
Cc: Len Brown <lenb@kernel.org>
Acked-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

1 files changed, 233 insertions, 0 deletions

diff --git a/drivers/pci/slot.c b/drivers/pci/slot.c
new file mode 100644
index 000000000000..7e5b85cbd948
--- /dev/null
+++ b/drivers/pci/slot.c
@@ -0,0 +1,233 @@
+/*
+ * drivers/pci/slot.c
+ * Copyright (C) 2006 Matthew Wilcox <matthew@wil.cx>
+ * Copyright (C) 2006-2008 Hewlett-Packard Development Company, L.P.
+ *      Alex Chiang <achiang@hp.com>
+ */
+
+#include <linux/kobject.h>
+#include <linux/pci.h>
+#include <linux/err.h>
+#include "pci.h"
+
+struct kset *pci_slots_kset;
+EXPORT_SYMBOL_GPL(pci_slots_kset);
+
+static ssize_t pci_slot_attr_show(struct kobject *kobj,
+                                        struct attribute *attr, char *buf)
+{
+        struct pci_slot *slot = to_pci_slot(kobj);
+        struct pci_slot_attribute *attribute = to_pci_slot_attr(attr);
+        return attribute->show ? attribute->show(slot, buf) : -EIO;
+}
+
+static ssize_t pci_slot_attr_store(struct kobject *kobj,
+                        struct attribute *attr, const char *buf, size_t len)
+{
+        struct pci_slot *slot = to_pci_slot(kobj);
+        struct pci_slot_attribute *attribute = to_pci_slot_attr(attr);
+        return attribute->store ? attribute->store(slot, buf, len) : -EIO;
+}
+
+static struct sysfs_ops pci_slot_sysfs_ops = {
+        .show = pci_slot_attr_show,
+        .store = pci_slot_attr_store,
+};
+
+static ssize_t address_read_file(struct pci_slot *slot, char *buf)
+{
+        if (slot->number == 0xff)
+                return sprintf(buf, "%04x:%02x\n",
+                                pci_domain_nr(slot->bus),
+                                slot->bus->number);
+        else
+                return sprintf(buf, "%04x:%02x:%02x\n",
+                                pci_domain_nr(slot->bus),
+                                slot->bus->number,
+                                slot->number);
+}
+
+static void pci_slot_release(struct kobject *kobj)
+{
+        struct pci_slot *slot = to_pci_slot(kobj);
+
+        pr_debug("%s: releasing pci_slot on %x:%d\n", __func__,
+                 slot->bus->number, slot->number);
+
+        list_del(&slot->list);
+
+        kfree(slot);
+}
+
+static struct pci_slot_attribute pci_slot_attr_address =
+        __ATTR(address, (S_IFREG | S_IRUGO), address_read_file, NULL);
+
+static struct attribute *pci_slot_default_attrs[] = {
+        &pci_slot_attr_address.attr,
+        NULL,
+};
+
+static struct kobj_type pci_slot_ktype = {
+        .sysfs_ops = &pci_slot_sysfs_ops,
+        .release = &pci_slot_release,
+        .default_attrs = pci_slot_default_attrs,
+};
+
+/**
+ * pci_create_slot - create or increment refcount for physical PCI slot
+ * @parent: struct pci_bus of parent bridge
+ * @slot_nr: PCI_SLOT(pci_dev->devfn) or -1 for placeholder
+ * @name: user visible string presented in /sys/bus/pci/slots/<name>
+ *
+ * PCI slots have first class attributes such as address, speed, width,
+ * and a &struct pci_slot is used to manage them. This interface will
+ * either return a new &struct pci_slot to the caller, or if the pci_slot
+ * already exists, its refcount will be incremented.
+ *
+ * Slots are uniquely identified by a @pci_bus, @slot_nr, @name tuple.
+ *
+ * Placeholder slots:
+ * In most cases, @pci_bus, @slot_nr will be sufficient to uniquely identify
+ * a slot. There is one notable exception - pSeries (rpaphp), where the
+ * @slot_nr cannot be determined until a device is actually inserted into
+ * the slot. In this scenario, the caller may pass -1 for @slot_nr.
+ *
+ * The following semantics are imposed when the caller passes @slot_nr ==
+ * -1. First, the check for existing %struct pci_slot is skipped, as the
+ * caller may know about several unpopulated slots on a given %struct
+ * pci_bus, and each slot would have a @slot_nr of -1.  Uniqueness for
+ * these slots is then determined by the @name parameter. We expect
+ * kobject_init_and_add() to warn us if the caller attempts to create
+ * multiple slots with the same name. The other change in semantics is
+ * user-visible, which is the 'address' parameter presented in sysfs will
+ * consist solely of a dddd:bb tuple, where dddd is the PCI domain of the
+ * %struct pci_bus and bb is the bus number. In other words, the devfn of
+ * the 'placeholder' slot will not be displayed.
+ */
+
+struct pci_slot *pci_create_slot(struct pci_bus *parent, int slot_nr,
+                                 const char *name)
+{
+        struct pci_slot *slot;
+        int err;
+
+        down_write(&pci_bus_sem);
+
+        if (slot_nr == -1)
+                goto placeholder;
+
+        /* If we've already created this slot, bump refcount and return. */
+        list_for_each_entry(slot, &parent->slots, list) {
+                if (slot->number == slot_nr) {
+                        kobject_get(&slot->kobj);
+                        pr_debug("%s: inc refcount to %d on %04x:%02x:%02x\n",
+                                 __func__,
+                                 atomic_read(&slot->kobj.kref.refcount),
+                                 pci_domain_nr(parent), parent->number,
+                                 slot_nr);
+                        goto out;
+                }
+        }
+
+placeholder:
+        slot = kzalloc(sizeof(*slot), GFP_KERNEL);
+        if (!slot) {
+                slot = ERR_PTR(-ENOMEM);
+                goto out;
+        }
+
+        slot->bus = parent;
+        slot->number = slot_nr;
+
+        slot->kobj.kset = pci_slots_kset;
+        err = kobject_init_and_add(&slot->kobj, &pci_slot_ktype, NULL,
+                                   "%s", name);
+        if (err) {
+                printk(KERN_ERR "Unable to register kobject %s\n", name);
+                goto err;
+        }
+
+        INIT_LIST_HEAD(&slot->list);
+        list_add(&slot->list, &parent->slots);
+
+        /* Don't care if debug printk has a -1 for slot_nr */
+        pr_debug("%s: created pci_slot on %04x:%02x:%02x\n",
+                 __func__, pci_domain_nr(parent), parent->number, slot_nr);
+
+ out:
+        up_write(&pci_bus_sem);
+        return slot;
+ err:
+        kfree(slot);
+        slot = ERR_PTR(err);
+        goto out;
+}
+EXPORT_SYMBOL_GPL(pci_create_slot);
+
+/**
+ * pci_update_slot_number - update %struct pci_slot -> number
+ * @slot - %struct pci_slot to update
+ * @slot_nr - new number for slot
+ *
+ * The primary purpose of this interface is to allow callers who earlier
+ * created a placeholder slot in pci_create_slot() by passing a -1 as
+ * slot_nr, to update their %struct pci_slot with the correct @slot_nr.
+ */
+
+void pci_update_slot_number(struct pci_slot *slot, int slot_nr)
+{
+        int name_count = 0;
+        struct pci_slot *tmp;
+
+        down_write(&pci_bus_sem);
+
+        list_for_each_entry(tmp, &slot->bus->slots, list) {
+                WARN_ON(tmp->number == slot_nr);
+                if (!strcmp(kobject_name(&tmp->kobj), kobject_name(&slot->kobj)))
+                        name_count++;
+        }
+
+        if (name_count > 1)
+                printk(KERN_WARNING "pci_update_slot_number found %d slots with the same name: %s\n", name_count, kobject_name(&slot->kobj));
+
+        slot->number = slot_nr;
+        up_write(&pci_bus_sem);
+}
+EXPORT_SYMBOL_GPL(pci_update_slot_number);
+
+/**
+ * pci_destroy_slot - decrement refcount for physical PCI slot
+ * @slot: struct pci_slot to decrement
+ *
+ * %struct pci_slot is refcounted, so destroying them is really easy; we
+ * just call kobject_put on its kobj and let our release methods do the
+ * rest.
+ */
+
+void pci_destroy_slot(struct pci_slot *slot)
+{
+        pr_debug("%s: dec refcount to %d on %04x:%02x:%02x\n", __func__,
+                 atomic_read(&slot->kobj.kref.refcount) - 1,
+                 pci_domain_nr(slot->bus), slot->bus->number, slot->number);
+
+        down_write(&pci_bus_sem);
+        kobject_put(&slot->kobj);
+        up_write(&pci_bus_sem);
+}
+EXPORT_SYMBOL_GPL(pci_destroy_slot);
+
+static int pci_slot_init(void)
+{
+        struct kset *pci_bus_kset;
+
+        pci_bus_kset = bus_get_kset(&pci_bus_type);
+        pci_slots_kset = kset_create_and_add("slots", NULL,
+                                                &pci_bus_kset->kobj);
+        if (!pci_slots_kset) {
+                printk(KERN_ERR "PCI: Slot initialization failure\n");
+                return -ENOMEM;
+        }
+        return 0;
+}
+
+subsys_initcall(pci_slot_init);