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 
14 struct kset *pci_slots_kset;
15 EXPORT_SYMBOL_GPL(pci_slots_kset);
16 
pci_slot_attr_show(struct kobject * kobj,struct attribute * attr,char * buf)17 static 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 
pci_slot_attr_store(struct kobject * kobj,struct attribute * attr,const char * buf,size_t len)25 static 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 
33 static const struct sysfs_ops pci_slot_sysfs_ops = {
34 	.show = pci_slot_attr_show,
35 	.store = pci_slot_attr_store,
36 };
37 
address_read_file(struct pci_slot * slot,char * buf)38 static 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 
bus_speed_read(enum pci_bus_speed speed,char * buf)51 static 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 
max_speed_read_file(struct pci_slot * slot,char * buf)56 static 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 
cur_speed_read_file(struct pci_slot * slot,char * buf)61 static 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 
pci_slot_release(struct kobject * kobj)66 static 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 
86 static struct pci_slot_attribute pci_slot_attr_address =
87 	__ATTR(address, S_IRUGO, address_read_file, NULL);
88 static struct pci_slot_attribute pci_slot_attr_max_speed =
89 	__ATTR(max_bus_speed, S_IRUGO, max_speed_read_file, NULL);
90 static struct pci_slot_attribute pci_slot_attr_cur_speed =
91 	__ATTR(cur_bus_speed, S_IRUGO, cur_speed_read_file, NULL);
92 
93 static 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 };
99 ATTRIBUTE_GROUPS(pci_slot_default);
100 
101 static 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 
make_slot_name(const char * name)107 static 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 
rename_slot(struct pci_slot * slot,const char * name)145 static 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 
pci_dev_assign_slot(struct pci_dev * dev)163 void 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 
get_slot(struct pci_bus * parent,int slot_nr)174 static 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  */
pci_create_slot(struct pci_bus * parent,int slot_nr,const char * name,struct hotplug_slot * hotplug)226 struct 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 
258 placeholder:
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 
295 out:
296 	kfree(slot_name);
297 	mutex_unlock(&pci_slot_mutex);
298 	return slot;
299 
300 put_slot:
301 	kobject_put(&slot->kobj);
302 err:
303 	slot = ERR_PTR(err);
304 	goto out;
305 }
306 EXPORT_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  */
pci_destroy_slot(struct pci_slot * slot)316 void 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 }
325 EXPORT_SYMBOL_GPL(pci_destroy_slot);
326 
pci_slot_init(void)327 static 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 
341 subsys_initcall(pci_slot_init);
342