xref: /openbmc/linux/drivers/pci/slot.c (revision 10473777)
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 
15 struct kset *pci_slots_kset;
16 EXPORT_SYMBOL_GPL(pci_slots_kset);
17 
pci_slot_attr_show(struct kobject * kobj,struct attribute * attr,char * buf)18 static 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 
pci_slot_attr_store(struct kobject * kobj,struct attribute * attr,const char * buf,size_t len)26 static 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 
34 static const struct sysfs_ops pci_slot_sysfs_ops = {
35 	.show = pci_slot_attr_show,
36 	.store = pci_slot_attr_store,
37 };
38 
address_read_file(struct pci_slot * slot,char * buf)39 static 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 
bus_speed_read(enum pci_bus_speed speed,char * buf)52 static 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 
max_speed_read_file(struct pci_slot * slot,char * buf)57 static 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 
cur_speed_read_file(struct pci_slot * slot,char * buf)62 static 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 
pci_slot_release(struct kobject * kobj)67 static 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 
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 ((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 
257 placeholder:
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 
295 out:
296 	kfree(slot_name);
297 	mutex_unlock(&pci_slot_mutex);
298 	return slot;
299 err:
300 	slot = ERR_PTR(err);
301 	goto out;
302 }
303 EXPORT_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  */
pci_destroy_slot(struct pci_slot * slot)313 void 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 }
322 EXPORT_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  */
pci_hp_create_module_link(struct pci_slot * pci_slot)333 void 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 }
350 EXPORT_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  */
pci_hp_remove_module_link(struct pci_slot * pci_slot)360 void pci_hp_remove_module_link(struct pci_slot *pci_slot)
361 {
362 	sysfs_remove_link(&pci_slot->kobj, "module");
363 }
364 EXPORT_SYMBOL_GPL(pci_hp_remove_module_link);
365 #endif
366 
pci_slot_init(void)367 static 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 
381 subsys_initcall(pci_slot_init);
382