slot.c

  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/pci.h>
 11#include <linux/err.h>
 12#include "pci.h"
 13
 14struct kset *pci_slots_kset;
 15EXPORT_SYMBOL_GPL(pci_slots_kset);
 16
 17static ssize_t pci_slot_attr_show(struct kobject *kobj,
 18					struct attribute *attr, char *buf)
 19{
 20	struct pci_slot *slot = to_pci_slot(kobj);
 21	struct pci_slot_attribute *attribute = to_pci_slot_attr(attr);
 22	return attribute->show ? attribute->show(slot, buf) : -EIO;
 23}
 24
 25static ssize_t pci_slot_attr_store(struct kobject *kobj,
 26			struct attribute *attr, const char *buf, size_t len)
 27{
 28	struct pci_slot *slot = to_pci_slot(kobj);
 29	struct pci_slot_attribute *attribute = to_pci_slot_attr(attr);
 30	return attribute->store ? attribute->store(slot, buf, len) : -EIO;
 31}
 32
 33static const struct sysfs_ops pci_slot_sysfs_ops = {
 34	.show = pci_slot_attr_show,
 35	.store = pci_slot_attr_store,
 36};
 37
 38static ssize_t address_read_file(struct pci_slot *slot, char *buf)
 39{
 40	if (slot->number == 0xff)
 41		return sysfs_emit(buf, "%04x:%02x\n",
 42				  pci_domain_nr(slot->bus),
 43				  slot->bus->number);
 44
 45	return sysfs_emit(buf, "%04x:%02x:%02x\n",
 46			  pci_domain_nr(slot->bus),
 47			  slot->bus->number,
 48			  slot->number);
 49}
 50
 51static ssize_t bus_speed_read(enum pci_bus_speed speed, char *buf)
 52{
 53	return sysfs_emit(buf, "%s\n", pci_speed_string(speed));
 54}
 55
 56static ssize_t max_speed_read_file(struct pci_slot *slot, char *buf)
 57{
 58	return bus_speed_read(slot->bus->max_bus_speed, buf);
 59}
 60
 61static ssize_t cur_speed_read_file(struct pci_slot *slot, char *buf)
 62{
 63	return bus_speed_read(slot->bus->cur_bus_speed, buf);
 64}
 65
 66static void pci_slot_release(struct kobject *kobj)
 67{
 68	struct pci_dev *dev;
 69	struct pci_slot *slot = to_pci_slot(kobj);
 70
 71	dev_dbg(&slot->bus->dev, "dev %02x, released physical slot %s\n",
 72		slot->number, pci_slot_name(slot));
 73
 74	down_read(&pci_bus_sem);
 75	list_for_each_entry(dev, &slot->bus->devices, bus_list)
 76		if (PCI_SLOT(dev->devfn) == slot->number)
 77			dev->slot = NULL;
 78	up_read(&pci_bus_sem);
 79
 80	list_del(&slot->list);
 81	pci_bus_put(slot->bus);
 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};
 99ATTRIBUTE_GROUPS(pci_slot_default);
100
101static const struct kobj_type pci_slot_ktype = {
102	.sysfs_ops = &pci_slot_sysfs_ops,
103	.release = &pci_slot_release,
104	.default_groups = pci_slot_default_groups,
105};
106
107static char *make_slot_name(const char *name)
108{
109	char *new_name;
110	int len, max, dup;
111
112	new_name = kstrdup(name, GFP_KERNEL);
113	if (!new_name)
114		return NULL;
115
116	/*
117	 * Make sure we hit the realloc case the first time through the
118	 * loop.  'len' will be strlen(name) + 3 at that point which is
119	 * enough space for "name-X" and the trailing NUL.
120	 */
121	len = strlen(name) + 2;
122	max = 1;
123	dup = 1;
124
125	for (;;) {
126		struct kobject *dup_slot;
127		dup_slot = kset_find_obj(pci_slots_kset, new_name);
128		if (!dup_slot)
129			break;
130		kobject_put(dup_slot);
131		if (dup == max) {
132			len++;
133			max *= 10;
134			kfree(new_name);
135			new_name = kmalloc(len, GFP_KERNEL);
136			if (!new_name)
137				break;
138		}
139		sprintf(new_name, "%s-%d", name, dup++);
140	}
141
142	return new_name;
143}
144
145static int rename_slot(struct pci_slot *slot, const char *name)
146{
147	int result = 0;
148	char *slot_name;
149
150	if (strcmp(pci_slot_name(slot), name) == 0)
151		return result;
152
153	slot_name = make_slot_name(name);
154	if (!slot_name)
155		return -ENOMEM;
156
157	result = kobject_rename(&slot->kobj, slot_name);
158	kfree(slot_name);
159
160	return result;
161}
162
163void pci_dev_assign_slot(struct pci_dev *dev)
164{
165	struct pci_slot *slot;
166
167	mutex_lock(&pci_slot_mutex);
168	list_for_each_entry(slot, &dev->bus->slots, list)
169		if (PCI_SLOT(dev->devfn) == slot->number)
170			dev->slot = slot;
171	mutex_unlock(&pci_slot_mutex);
172}
173
174static struct pci_slot *get_slot(struct pci_bus *parent, int slot_nr)
175{
176	struct pci_slot *slot;
177
178	/* We already hold pci_slot_mutex */
179	list_for_each_entry(slot, &parent->slots, list)
180		if (slot->number == slot_nr) {
181			kobject_get(&slot->kobj);
182			return slot;
183		}
184
185	return NULL;
186}
187
188/**
189 * pci_create_slot - create or increment refcount for physical PCI slot
190 * @parent: struct pci_bus of parent bridge
191 * @slot_nr: PCI_SLOT(pci_dev->devfn) or -1 for placeholder
192 * @name: user visible string presented in /sys/bus/pci/slots/<name>
193 * @hotplug: set if caller is hotplug driver, NULL otherwise
194 *
195 * PCI slots have first class attributes such as address, speed, width,
196 * and a &struct pci_slot is used to manage them. This interface will
197 * either return a new &struct pci_slot to the caller, or if the pci_slot
198 * already exists, its refcount will be incremented.
199 *
200 * Slots are uniquely identified by a @pci_bus, @slot_nr tuple.
201 *
202 * There are known platforms with broken firmware that assign the same
203 * name to multiple slots. Workaround these broken platforms by renaming
204 * the slots on behalf of the caller. If firmware assigns name N to
205 * multiple slots:
206 *
207 * The first slot is assigned N
208 * The second slot is assigned N-1
209 * The third slot is assigned N-2
210 * etc.
211 *
212 * Placeholder slots:
213 * In most cases, @pci_bus, @slot_nr will be sufficient to uniquely identify
214 * a slot. There is one notable exception - pSeries (rpaphp), where the
215 * @slot_nr cannot be determined until a device is actually inserted into
216 * the slot. In this scenario, the caller may pass -1 for @slot_nr.
217 *
218 * The following semantics are imposed when the caller passes @slot_nr ==
219 * -1. First, we no longer check for an existing %struct pci_slot, as there
220 * may be many slots with @slot_nr of -1.  The other change in semantics is
221 * user-visible, which is the 'address' parameter presented in sysfs will
222 * consist solely of a dddd:bb tuple, where dddd is the PCI domain of the
223 * %struct pci_bus and bb is the bus number. In other words, the devfn of
224 * the 'placeholder' slot will not be displayed.
225 */
226struct pci_slot *pci_create_slot(struct pci_bus *parent, int slot_nr,
227				 const char *name,
228				 struct hotplug_slot *hotplug)
229{
230	struct pci_dev *dev;
231	struct pci_slot *slot;
232	int err = 0;
233	char *slot_name = NULL;
234
235	mutex_lock(&pci_slot_mutex);
236
237	if (slot_nr == -1)
238		goto placeholder;
239
240	/*
241	 * Hotplug drivers are allowed to rename an existing slot,
242	 * but only if not already claimed.
243	 */
244	slot = get_slot(parent, slot_nr);
245	if (slot) {
246		if (hotplug) {
247			if (slot->hotplug) {
248				err = -EBUSY;
249				goto put_slot;
250			}
251			err = rename_slot(slot, name);
252			if (err)
253				goto put_slot;
254		}
255		goto out;
256	}
257
258placeholder:
259	slot = kzalloc(sizeof(*slot), GFP_KERNEL);
260	if (!slot) {
261		err = -ENOMEM;
262		goto err;
263	}
264
265	slot->bus = pci_bus_get(parent);
266	slot->number = slot_nr;
267
268	slot->kobj.kset = pci_slots_kset;
269
270	slot_name = make_slot_name(name);
271	if (!slot_name) {
272		err = -ENOMEM;
273		pci_bus_put(slot->bus);
274		kfree(slot);
275		goto err;
276	}
277
278	INIT_LIST_HEAD(&slot->list);
279	list_add(&slot->list, &parent->slots);
280
281	err = kobject_init_and_add(&slot->kobj, &pci_slot_ktype, NULL,
282				   "%s", slot_name);
283	if (err)
284		goto put_slot;
285
286	down_read(&pci_bus_sem);
287	list_for_each_entry(dev, &parent->devices, bus_list)
288		if (PCI_SLOT(dev->devfn) == slot_nr)
289			dev->slot = slot;
290	up_read(&pci_bus_sem);
291
292	dev_dbg(&parent->dev, "dev %02x, created physical slot %s\n",
293		slot_nr, pci_slot_name(slot));
294
295out:
296	kfree(slot_name);
297	mutex_unlock(&pci_slot_mutex);
298	return slot;
299
300put_slot:
301	kobject_put(&slot->kobj);
302err:
303	slot = ERR_PTR(err);
304	goto out;
305}
306EXPORT_SYMBOL_GPL(pci_create_slot);
307
308/**
309 * pci_destroy_slot - decrement refcount for physical PCI slot
310 * @slot: struct pci_slot to decrement
311 *
312 * %struct pci_slot is refcounted, so destroying them is really easy; we
313 * just call kobject_put on its kobj and let our release methods do the
314 * rest.
315 */
316void pci_destroy_slot(struct pci_slot *slot)
317{
318	dev_dbg(&slot->bus->dev, "dev %02x, dec refcount to %d\n",
319		slot->number, kref_read(&slot->kobj.kref) - 1);
320
321	mutex_lock(&pci_slot_mutex);
322	kobject_put(&slot->kobj);
323	mutex_unlock(&pci_slot_mutex);
324}
325EXPORT_SYMBOL_GPL(pci_destroy_slot);
326
327static int pci_slot_init(void)
328{
329	struct kset *pci_bus_kset;
330
331	pci_bus_kset = bus_get_kset(&pci_bus_type);
332	pci_slots_kset = kset_create_and_add("slots", NULL,
333						&pci_bus_kset->kobj);
334	if (!pci_slots_kset) {
335		pr_err("PCI: Slot initialization failure\n");
336		return -ENOMEM;
337	}
338	return 0;
339}
340
341subsys_initcall(pci_slot_init);