// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2006 Matthew Wilcox <matthew@wil.cx>
 * Copyright (C) 2006-2009 Hewlett-Packard Development Company, L.P.
 *      Alex Chiang <achiang@hp.com>
 */

#include <linux/kobject.h>
#include <linux/slab.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 const 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 sysfs_emit(buf, "%04x:%02x\n",
                                  pci_domain_nr(slot->bus),
                                  slot->bus->number);

        return sysfs_emit(buf, "%04x:%02x:%02x\n",
                          pci_domain_nr(slot->bus),
                          slot->bus->number,
                          slot->number);
}

static ssize_t bus_speed_read(enum pci_bus_speed speed, char *buf)
{
        return sysfs_emit(buf, "%s\n", pci_speed_string(speed));
}

static ssize_t max_speed_read_file(struct pci_slot *slot, char *buf)
{
        return bus_speed_read(slot->bus->max_bus_speed, buf);
}

static ssize_t cur_speed_read_file(struct pci_slot *slot, char *buf)
{
        return bus_speed_read(slot->bus->cur_bus_speed, buf);
}

static void pci_slot_release(struct kobject *kobj)
{
        struct pci_dev *dev;
        struct pci_slot *slot = to_pci_slot(kobj);

        dev_dbg(&slot->bus->dev, "dev %02x, released physical slot %s\n",
                slot->number, pci_slot_name(slot));

        down_read(&pci_bus_sem);
        list_for_each_entry(dev, &slot->bus->devices, bus_list)
                if (PCI_SLOT(dev->devfn) == slot->number)
                        dev->slot = NULL;
        up_read(&pci_bus_sem);

        list_del(&slot->list);
        pci_bus_put(slot->bus);

        kfree(slot);
}

static struct pci_slot_attribute pci_slot_attr_address =
        __ATTR(address, S_IRUGO, address_read_file, NULL);
static struct pci_slot_attribute pci_slot_attr_max_speed =
        __ATTR(max_bus_speed, S_IRUGO, max_speed_read_file, NULL);
static struct pci_slot_attribute pci_slot_attr_cur_speed =
        __ATTR(cur_bus_speed, S_IRUGO, cur_speed_read_file, NULL);

static struct attribute *pci_slot_default_attrs[] = {
        &pci_slot_attr_address.attr,
        &pci_slot_attr_max_speed.attr,
        &pci_slot_attr_cur_speed.attr,
        NULL,
};
ATTRIBUTE_GROUPS(pci_slot_default);

static const struct kobj_type pci_slot_ktype = {
        .sysfs_ops = &pci_slot_sysfs_ops,
        .release = &pci_slot_release,
        .default_groups = pci_slot_default_groups,
};

static char *make_slot_name(const char *name)
{
        char *new_name;
        int len, max, dup;

        new_name = kstrdup(name, GFP_KERNEL);
        if (!new_name)
                return NULL;

        /*
         * Make sure we hit the realloc case the first time through the
         * loop.  'len' will be strlen(name) + 3 at that point which is
         * enough space for "name-X" and the trailing NUL.
         */
        len = strlen(name) + 2;
        max = 1;
        dup = 1;

        for (;;) {
                struct kobject *dup_slot;
                dup_slot = kset_find_obj(pci_slots_kset, new_name);
                if (!dup_slot)
                        break;
                kobject_put(dup_slot);
                if (dup == max) {
                        len++;
                        max *= 10;
                        kfree(new_name);
                        new_name = kmalloc(len, GFP_KERNEL);
                        if (!new_name)
                                break;
                }
                sprintf(new_name, "%s-%d", name, dup++);
        }

        return new_name;
}

static int rename_slot(struct pci_slot *slot, const char *name)
{
        int result = 0;
        char *slot_name;

        if (strcmp(pci_slot_name(slot), name) == 0)
                return result;

        slot_name = make_slot_name(name);
        if (!slot_name)
                return -ENOMEM;

        result = kobject_rename(&slot->kobj, slot_name);
        kfree(slot_name);

        return result;
}

void pci_dev_assign_slot(struct pci_dev *dev)
{
        struct pci_slot *slot;

        mutex_lock(&pci_slot_mutex);
        list_for_each_entry(slot, &dev->bus->slots, list)
                if (PCI_SLOT(dev->devfn) == slot->number)
                        dev->slot = slot;
        mutex_unlock(&pci_slot_mutex);
}

static struct pci_slot *get_slot(struct pci_bus *parent, int slot_nr)
{
        struct pci_slot *slot;

        /* We already hold pci_slot_mutex */
        list_for_each_entry(slot, &parent->slots, list)
                if (slot->number == slot_nr) {
                        kobject_get(&slot->kobj);
                        return slot;
                }

        return NULL;
}

/**
 * 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>
 * @hotplug: set if caller is hotplug driver, NULL otherwise
 *
 * 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 tuple.
 *
 * There are known platforms with broken firmware that assign the same
 * name to multiple slots. Workaround these broken platforms by renaming
 * the slots on behalf of the caller. If firmware assigns name N to
 * multiple slots:
 *
 * The first slot is assigned N
 * The second slot is assigned N-1
 * The third slot is assigned N-2
 * etc.
 *
 * 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, we no longer check for an existing %struct pci_slot, as there
 * may be many slots with @slot_nr of -1.  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 hotplug_slot *hotplug)
{
        struct pci_dev *dev;
        struct pci_slot *slot;
        int err = 0;
        char *slot_name = NULL;

        mutex_lock(&pci_slot_mutex);

        if (slot_nr == -1)
                goto placeholder;

        /*
         * Hotplug drivers are allowed to rename an existing slot,
         * but only if not already claimed.
         */
        slot = get_slot(parent, slot_nr);
        if (slot) {
                if (hotplug) {
                        if (slot->hotplug) {
                                err = -EBUSY;
                                goto put_slot;
                        }
                        err = rename_slot(slot, name);
                        if (err)
                                goto put_slot;
                }
                goto out;
        }

placeholder:
        slot = kzalloc_obj(*slot);
        if (!slot) {
                err = -ENOMEM;
                goto err;
        }

        slot->bus = pci_bus_get(parent);
        slot->number = slot_nr;

        slot->kobj.kset = pci_slots_kset;

        slot_name = make_slot_name(name);
        if (!slot_name) {
                err = -ENOMEM;
                pci_bus_put(slot->bus);
                kfree(slot);
                goto err;
        }

        INIT_LIST_HEAD(&slot->list);
        list_add(&slot->list, &parent->slots);

        err = kobject_init_and_add(&slot->kobj, &pci_slot_ktype, NULL,
                                   "%s", slot_name);
        if (err)
                goto put_slot;

        down_read(&pci_bus_sem);
        list_for_each_entry(dev, &parent->devices, bus_list)
                if (PCI_SLOT(dev->devfn) == slot_nr)
                        dev->slot = slot;
        up_read(&pci_bus_sem);

        dev_dbg(&parent->dev, "dev %02x, created physical slot %s\n",
                slot_nr, pci_slot_name(slot));

out:
        kfree(slot_name);
        mutex_unlock(&pci_slot_mutex);
        return slot;

put_slot:
        kobject_put(&slot->kobj);
err:
        slot = ERR_PTR(err);
        goto out;
}
EXPORT_SYMBOL_GPL(pci_create_slot);

/**
 * 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)
{
        dev_dbg(&slot->bus->dev, "dev %02x, dec refcount to %d\n",
                slot->number, kref_read(&slot->kobj.kref) - 1);

        mutex_lock(&pci_slot_mutex);
        kobject_put(&slot->kobj);
        mutex_unlock(&pci_slot_mutex);
}
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) {
                pr_err("PCI: Slot initialization failure\n");
                return -ENOMEM;
        }
        return 0;
}

subsys_initcall(pci_slot_init);