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/module.h>
11#include <linux/pci.h>
12#include <linux/err.h>
13#include "pci.h"
14
15struct kset *pci_slots_kset;
16EXPORT_SYMBOL_GPL(pci_slots_kset);
17
18static ssize_t pci_slot_attr_show(struct kobject *kobj,
19					struct attribute *attr, char *buf)
20{
21	struct pci_slot *slot = to_pci_slot(kobj);
22	struct pci_slot_attribute *attribute = to_pci_slot_attr(attr);
23	return attribute->show ? attribute->show(slot, buf) : -EIO;
24}
25
26static ssize_t pci_slot_attr_store(struct kobject *kobj,
27			struct attribute *attr, const char *buf, size_t len)
28{
29	struct pci_slot *slot = to_pci_slot(kobj);
30	struct pci_slot_attribute *attribute = to_pci_slot_attr(attr);
31	return attribute->store ? attribute->store(slot, buf, len) : -EIO;
32}
33
34static const struct sysfs_ops pci_slot_sysfs_ops = {
35	.show = pci_slot_attr_show,
36	.store = pci_slot_attr_store,
37};
38
39static ssize_t address_read_file(struct pci_slot *slot, char *buf)
40{
41	if (slot->number == 0xff)
42		return sysfs_emit(buf, "%04x:%02x\n",
43				  pci_domain_nr(slot->bus),
44				  slot->bus->number);
45
46	return sysfs_emit(buf, "%04x:%02x:%02x\n",
47			  pci_domain_nr(slot->bus),
48			  slot->bus->number,
49			  slot->number);
50}
51
52static ssize_t bus_speed_read(enum pci_bus_speed speed, char *buf)
53{
54	return sysfs_emit(buf, "%s\n", pci_speed_string(speed));
55}
56
57static ssize_t max_speed_read_file(struct pci_slot *slot, char *buf)
58{
59	return bus_speed_read(slot->bus->max_bus_speed, buf);
60}
61
62static ssize_t cur_speed_read_file(struct pci_slot *slot, char *buf)
63{
64	return bus_speed_read(slot->bus->cur_bus_speed, buf);
65}
66
67static void pci_slot_release(struct kobject *kobj)
68{
69	struct pci_dev *dev;
70	struct pci_slot *slot = to_pci_slot(kobj);
71
72	dev_dbg(&slot->bus->dev, "dev %02x, released physical slot %s\n",
73		slot->number, pci_slot_name(slot));
74
75	down_read(&pci_bus_sem);
76	list_for_each_entry(dev, &slot->bus->devices, bus_list)
77		if (PCI_SLOT(dev->devfn) == slot->number)
78			dev->slot = NULL;
79	up_read(&pci_bus_sem);
80
81	list_del(&slot->list);
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 ((err = slot->hotplug ? -EBUSY : 0)
248			     || (err = rename_slot(slot, name))) {
249				kobject_put(&slot->kobj);
250				slot = NULL;
251				goto err;
252			}
253		}
254		goto out;
255	}
256
257placeholder:
258	slot = kzalloc(sizeof(*slot), GFP_KERNEL);
259	if (!slot) {
260		err = -ENOMEM;
261		goto err;
262	}
263
264	slot->bus = parent;
265	slot->number = slot_nr;
266
267	slot->kobj.kset = pci_slots_kset;
268
269	slot_name = make_slot_name(name);
270	if (!slot_name) {
271		err = -ENOMEM;
272		kfree(slot);
273		goto err;
274	}
275
276	INIT_LIST_HEAD(&slot->list);
277	list_add(&slot->list, &parent->slots);
278
279	err = kobject_init_and_add(&slot->kobj, &pci_slot_ktype, NULL,
280				   "%s", slot_name);
281	if (err) {
282		kobject_put(&slot->kobj);
283		goto err;
284	}
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;
299err:
300	slot = ERR_PTR(err);
301	goto out;
302}
303EXPORT_SYMBOL_GPL(pci_create_slot);
304
305/**
306 * pci_destroy_slot - decrement refcount for physical PCI slot
307 * @slot: struct pci_slot to decrement
308 *
309 * %struct pci_slot is refcounted, so destroying them is really easy; we
310 * just call kobject_put on its kobj and let our release methods do the
311 * rest.
312 */
313void pci_destroy_slot(struct pci_slot *slot)
314{
315	dev_dbg(&slot->bus->dev, "dev %02x, dec refcount to %d\n",
316		slot->number, kref_read(&slot->kobj.kref) - 1);
317
318	mutex_lock(&pci_slot_mutex);
319	kobject_put(&slot->kobj);
320	mutex_unlock(&pci_slot_mutex);
321}
322EXPORT_SYMBOL_GPL(pci_destroy_slot);
323
324#if defined(CONFIG_HOTPLUG_PCI) || defined(CONFIG_HOTPLUG_PCI_MODULE)
325#include <linux/pci_hotplug.h>
326/**
327 * pci_hp_create_module_link - create symbolic link to hotplug driver module
328 * @pci_slot: struct pci_slot
329 *
330 * Helper function for pci_hotplug_core.c to create symbolic link to
331 * the hotplug driver module.
332 */
333void pci_hp_create_module_link(struct pci_slot *pci_slot)
334{
335	struct hotplug_slot *slot = pci_slot->hotplug;
336	struct kobject *kobj = NULL;
337	int ret;
338
339	if (!slot || !slot->ops)
340		return;
341	kobj = kset_find_obj(module_kset, slot->mod_name);
342	if (!kobj)
343		return;
344	ret = sysfs_create_link(&pci_slot->kobj, kobj, "module");
345	if (ret)
346		dev_err(&pci_slot->bus->dev, "Error creating sysfs link (%d)\n",
347			ret);
348	kobject_put(kobj);
349}
350EXPORT_SYMBOL_GPL(pci_hp_create_module_link);
351
352/**
353 * pci_hp_remove_module_link - remove symbolic link to the hotplug driver
354 * 	module.
355 * @pci_slot: struct pci_slot
356 *
357 * Helper function for pci_hotplug_core.c to remove symbolic link to
358 * the hotplug driver module.
359 */
360void pci_hp_remove_module_link(struct pci_slot *pci_slot)
361{
362	sysfs_remove_link(&pci_slot->kobj, "module");
363}
364EXPORT_SYMBOL_GPL(pci_hp_remove_module_link);
365#endif
366
367static int pci_slot_init(void)
368{
369	struct kset *pci_bus_kset;
370
371	pci_bus_kset = bus_get_kset(&pci_bus_type);
372	pci_slots_kset = kset_create_and_add("slots", NULL,
373						&pci_bus_kset->kobj);
374	if (!pci_slots_kset) {
375		pr_err("PCI: Slot initialization failure\n");
376		return -ENOMEM;
377	}
378	return 0;
379}
380
381subsys_initcall(pci_slot_init);
382