1// SPDX-License-Identifier: GPL-2.0
  2/* Copyright(c) 2017-2018 Intel Corporation. All rights reserved. */
  3#include <linux/memremap.h>
  4#include <linux/device.h>
  5#include <linux/mutex.h>
  6#include <linux/list.h>
  7#include <linux/slab.h>
  8#include <linux/dax.h>
  9#include "dax-private.h"
 10#include "bus.h"
 11
 12static struct class *dax_class;
 13
 14static DEFINE_MUTEX(dax_bus_lock);
 15
 16#define DAX_NAME_LEN 30
 17struct dax_id {
 18	struct list_head list;
 19	char dev_name[DAX_NAME_LEN];
 20};
 21
 22static int dax_bus_uevent(struct device *dev, struct kobj_uevent_env *env)
 23{
 24	/*
 25	 * We only ever expect to handle device-dax instances, i.e. the
 26	 * @type argument to MODULE_ALIAS_DAX_DEVICE() is always zero
 27	 */
 28	return add_uevent_var(env, "MODALIAS=" DAX_DEVICE_MODALIAS_FMT, 0);
 29}
 30
 31static struct dax_device_driver *to_dax_drv(struct device_driver *drv)
 32{
 33	return container_of(drv, struct dax_device_driver, drv);
 34}
 35
 36static struct dax_id *__dax_match_id(struct dax_device_driver *dax_drv,
 37		const char *dev_name)
 38{
 39	struct dax_id *dax_id;
 40
 41	lockdep_assert_held(&dax_bus_lock);
 42
 43	list_for_each_entry(dax_id, &dax_drv->ids, list)
 44		if (sysfs_streq(dax_id->dev_name, dev_name))
 45			return dax_id;
 46	return NULL;
 47}
 48
 49static int dax_match_id(struct dax_device_driver *dax_drv, struct device *dev)
 50{
 51	int match;
 52
 53	mutex_lock(&dax_bus_lock);
 54	match = !!__dax_match_id(dax_drv, dev_name(dev));
 55	mutex_unlock(&dax_bus_lock);
 56
 57	return match;
 58}
 59
 60enum id_action {
 61	ID_REMOVE,
 62	ID_ADD,
 63};
 64
 65static ssize_t do_id_store(struct device_driver *drv, const char *buf,
 66		size_t count, enum id_action action)
 67{
 68	struct dax_device_driver *dax_drv = to_dax_drv(drv);
 69	unsigned int region_id, id;
 70	char devname[DAX_NAME_LEN];
 71	struct dax_id *dax_id;
 72	ssize_t rc = count;
 73	int fields;
 74
 75	fields = sscanf(buf, "dax%d.%d", &region_id, &id);
 76	if (fields != 2)
 77		return -EINVAL;
 78	sprintf(devname, "dax%d.%d", region_id, id);
 79	if (!sysfs_streq(buf, devname))
 80		return -EINVAL;
 81
 82	mutex_lock(&dax_bus_lock);
 83	dax_id = __dax_match_id(dax_drv, buf);
 84	if (!dax_id) {
 85		if (action == ID_ADD) {
 86			dax_id = kzalloc(sizeof(*dax_id), GFP_KERNEL);
 87			if (dax_id) {
 88				strncpy(dax_id->dev_name, buf, DAX_NAME_LEN);
 89				list_add(&dax_id->list, &dax_drv->ids);
 90			} else
 91				rc = -ENOMEM;
 92		} else
 93			/* nothing to remove */;
 94	} else if (action == ID_REMOVE) {
 95		list_del(&dax_id->list);
 96		kfree(dax_id);
 97	} else
 98		/* dax_id already added */;
 99	mutex_unlock(&dax_bus_lock);
100
101	if (rc < 0)
102		return rc;
103	if (action == ID_ADD)
104		rc = driver_attach(drv);
105	if (rc)
106		return rc;
107	return count;
108}
109
110static ssize_t new_id_store(struct device_driver *drv, const char *buf,
111		size_t count)
112{
113	return do_id_store(drv, buf, count, ID_ADD);
114}
115static DRIVER_ATTR_WO(new_id);
116
117static ssize_t remove_id_store(struct device_driver *drv, const char *buf,
118		size_t count)
119{
120	return do_id_store(drv, buf, count, ID_REMOVE);
121}
122static DRIVER_ATTR_WO(remove_id);
123
124static struct attribute *dax_drv_attrs[] = {
125	&driver_attr_new_id.attr,
126	&driver_attr_remove_id.attr,
127	NULL,
128};
129ATTRIBUTE_GROUPS(dax_drv);
130
131static int dax_bus_match(struct device *dev, struct device_driver *drv);
132
133static struct bus_type dax_bus_type = {
134	.name = "dax",
135	.uevent = dax_bus_uevent,
136	.match = dax_bus_match,
137	.drv_groups = dax_drv_groups,
138};
139
140static int dax_bus_match(struct device *dev, struct device_driver *drv)
141{
142	struct dax_device_driver *dax_drv = to_dax_drv(drv);
143
144	/*
145	 * All but the 'device-dax' driver, which has 'match_always'
146	 * set, requires an exact id match.
147	 */
148	if (dax_drv->match_always)
149		return 1;
150
151	return dax_match_id(dax_drv, dev);
152}
153
154/*
155 * Rely on the fact that drvdata is set before the attributes are
156 * registered, and that the attributes are unregistered before drvdata
157 * is cleared to assume that drvdata is always valid.
158 */
159static ssize_t id_show(struct device *dev,
160		struct device_attribute *attr, char *buf)
161{
162	struct dax_region *dax_region = dev_get_drvdata(dev);
163
164	return sprintf(buf, "%d\n", dax_region->id);
165}
166static DEVICE_ATTR_RO(id);
167
168static ssize_t region_size_show(struct device *dev,
169		struct device_attribute *attr, char *buf)
170{
171	struct dax_region *dax_region = dev_get_drvdata(dev);
172
173	return sprintf(buf, "%llu\n", (unsigned long long)
174			resource_size(&dax_region->res));
175}
176static struct device_attribute dev_attr_region_size = __ATTR(size, 0444,
177		region_size_show, NULL);
178
179static ssize_t align_show(struct device *dev,
180		struct device_attribute *attr, char *buf)
181{
182	struct dax_region *dax_region = dev_get_drvdata(dev);
183
184	return sprintf(buf, "%u\n", dax_region->align);
185}
186static DEVICE_ATTR_RO(align);
187
188static struct attribute *dax_region_attributes[] = {
189	&dev_attr_region_size.attr,
190	&dev_attr_align.attr,
191	&dev_attr_id.attr,
192	NULL,
193};
194
195static const struct attribute_group dax_region_attribute_group = {
196	.name = "dax_region",
197	.attrs = dax_region_attributes,
198};
199
200static const struct attribute_group *dax_region_attribute_groups[] = {
201	&dax_region_attribute_group,
202	NULL,
203};
204
205static void dax_region_free(struct kref *kref)
206{
207	struct dax_region *dax_region;
208
209	dax_region = container_of(kref, struct dax_region, kref);
210	kfree(dax_region);
211}
212
213void dax_region_put(struct dax_region *dax_region)
214{
215	kref_put(&dax_region->kref, dax_region_free);
216}
217EXPORT_SYMBOL_GPL(dax_region_put);
218
219static void dax_region_unregister(void *region)
220{
221	struct dax_region *dax_region = region;
222
223	sysfs_remove_groups(&dax_region->dev->kobj,
224			dax_region_attribute_groups);
225	dax_region_put(dax_region);
226}
227
228struct dax_region *alloc_dax_region(struct device *parent, int region_id,
229		struct resource *res, int target_node, unsigned int align,
230		unsigned long pfn_flags)
231{
232	struct dax_region *dax_region;
233
234	/*
235	 * The DAX core assumes that it can store its private data in
236	 * parent->driver_data. This WARN is a reminder / safeguard for
237	 * developers of device-dax drivers.
238	 */
239	if (dev_get_drvdata(parent)) {
240		dev_WARN(parent, "dax core failed to setup private data\n");
241		return NULL;
242	}
243
244	if (!IS_ALIGNED(res->start, align)
245			|| !IS_ALIGNED(resource_size(res), align))
246		return NULL;
247
248	dax_region = kzalloc(sizeof(*dax_region), GFP_KERNEL);
249	if (!dax_region)
250		return NULL;
251
252	dev_set_drvdata(parent, dax_region);
253	memcpy(&dax_region->res, res, sizeof(*res));
254	dax_region->pfn_flags = pfn_flags;
255	kref_init(&dax_region->kref);
256	dax_region->id = region_id;
257	dax_region->align = align;
258	dax_region->dev = parent;
259	dax_region->target_node = target_node;
260	if (sysfs_create_groups(&parent->kobj, dax_region_attribute_groups)) {
261		kfree(dax_region);
262		return NULL;
263	}
264
265	kref_get(&dax_region->kref);
266	if (devm_add_action_or_reset(parent, dax_region_unregister, dax_region))
267		return NULL;
268	return dax_region;
269}
270EXPORT_SYMBOL_GPL(alloc_dax_region);
271
272static ssize_t size_show(struct device *dev,
273		struct device_attribute *attr, char *buf)
274{
275	struct dev_dax *dev_dax = to_dev_dax(dev);
276	unsigned long long size = resource_size(&dev_dax->region->res);
277
278	return sprintf(buf, "%llu\n", size);
279}
280static DEVICE_ATTR_RO(size);
281
282static int dev_dax_target_node(struct dev_dax *dev_dax)
283{
284	struct dax_region *dax_region = dev_dax->region;
285
286	return dax_region->target_node;
287}
288
289static ssize_t target_node_show(struct device *dev,
290		struct device_attribute *attr, char *buf)
291{
292	struct dev_dax *dev_dax = to_dev_dax(dev);
293
294	return sprintf(buf, "%d\n", dev_dax_target_node(dev_dax));
295}
296static DEVICE_ATTR_RO(target_node);
297
298static unsigned long long dev_dax_resource(struct dev_dax *dev_dax)
299{
300	struct dax_region *dax_region = dev_dax->region;
301
302	return dax_region->res.start;
303}
304
305static ssize_t resource_show(struct device *dev,
306		struct device_attribute *attr, char *buf)
307{
308	struct dev_dax *dev_dax = to_dev_dax(dev);
309
310	return sprintf(buf, "%#llx\n", dev_dax_resource(dev_dax));
311}
312static DEVICE_ATTR_RO(resource);
313
314static ssize_t modalias_show(struct device *dev, struct device_attribute *attr,
315		char *buf)
316{
317	/*
318	 * We only ever expect to handle device-dax instances, i.e. the
319	 * @type argument to MODULE_ALIAS_DAX_DEVICE() is always zero
320	 */
321	return sprintf(buf, DAX_DEVICE_MODALIAS_FMT "\n", 0);
322}
323static DEVICE_ATTR_RO(modalias);
324
325static umode_t dev_dax_visible(struct kobject *kobj, struct attribute *a, int n)
326{
327	struct device *dev = container_of(kobj, struct device, kobj);
328	struct dev_dax *dev_dax = to_dev_dax(dev);
329
330	if (a == &dev_attr_target_node.attr && dev_dax_target_node(dev_dax) < 0)
331		return 0;
332	if (a == &dev_attr_resource.attr)
333		return 0400;
334	return a->mode;
335}
336
337static struct attribute *dev_dax_attributes[] = {
338	&dev_attr_modalias.attr,
339	&dev_attr_size.attr,
340	&dev_attr_target_node.attr,
341	&dev_attr_resource.attr,
342	NULL,
343};
344
345static const struct attribute_group dev_dax_attribute_group = {
346	.attrs = dev_dax_attributes,
347	.is_visible = dev_dax_visible,
348};
349
350static const struct attribute_group *dax_attribute_groups[] = {
351	&dev_dax_attribute_group,
352	NULL,
353};
354
355void kill_dev_dax(struct dev_dax *dev_dax)
356{
357	struct dax_device *dax_dev = dev_dax->dax_dev;
358	struct inode *inode = dax_inode(dax_dev);
359
360	kill_dax(dax_dev);
361	unmap_mapping_range(inode->i_mapping, 0, 0, 1);
362}
363EXPORT_SYMBOL_GPL(kill_dev_dax);
364
365static void dev_dax_release(struct device *dev)
366{
367	struct dev_dax *dev_dax = to_dev_dax(dev);
368	struct dax_region *dax_region = dev_dax->region;
369	struct dax_device *dax_dev = dev_dax->dax_dev;
370
371	dax_region_put(dax_region);
372	put_dax(dax_dev);
373	kfree(dev_dax);
374}
375
376static void unregister_dev_dax(void *dev)
377{
378	struct dev_dax *dev_dax = to_dev_dax(dev);
379
380	dev_dbg(dev, "%s\n", __func__);
381
382	kill_dev_dax(dev_dax);
383	device_del(dev);
384	put_device(dev);
385}
386
387struct dev_dax *__devm_create_dev_dax(struct dax_region *dax_region, int id,
388		struct dev_pagemap *pgmap, enum dev_dax_subsys subsys)
389{
390	struct device *parent = dax_region->dev;
391	struct dax_device *dax_dev;
392	struct dev_dax *dev_dax;
393	struct inode *inode;
394	struct device *dev;
395	int rc = -ENOMEM;
396
397	if (id < 0)
398		return ERR_PTR(-EINVAL);
399
400	dev_dax = kzalloc(sizeof(*dev_dax), GFP_KERNEL);
401	if (!dev_dax)
402		return ERR_PTR(-ENOMEM);
403
404	memcpy(&dev_dax->pgmap, pgmap, sizeof(*pgmap));
405
406	/*
407	 * No 'host' or dax_operations since there is no access to this
408	 * device outside of mmap of the resulting character device.
409	 */
410	dax_dev = alloc_dax(dev_dax, NULL, NULL, DAXDEV_F_SYNC);
411	if (!dax_dev)
412		goto err;
413
414	/* a device_dax instance is dead while the driver is not attached */
415	kill_dax(dax_dev);
416
417	/* from here on we're committed to teardown via dax_dev_release() */
418	dev = &dev_dax->dev;
419	device_initialize(dev);
420
421	dev_dax->dax_dev = dax_dev;
422	dev_dax->region = dax_region;
423	dev_dax->target_node = dax_region->target_node;
424	kref_get(&dax_region->kref);
425
426	inode = dax_inode(dax_dev);
427	dev->devt = inode->i_rdev;
428	if (subsys == DEV_DAX_BUS)
429		dev->bus = &dax_bus_type;
430	else
431		dev->class = dax_class;
432	dev->parent = parent;
433	dev->groups = dax_attribute_groups;
434	dev->release = dev_dax_release;
435	dev_set_name(dev, "dax%d.%d", dax_region->id, id);
436
437	rc = device_add(dev);
438	if (rc) {
439		kill_dev_dax(dev_dax);
440		put_device(dev);
441		return ERR_PTR(rc);
442	}
443
444	rc = devm_add_action_or_reset(dax_region->dev, unregister_dev_dax, dev);
445	if (rc)
446		return ERR_PTR(rc);
447
448	return dev_dax;
449
450 err:
451	kfree(dev_dax);
452
453	return ERR_PTR(rc);
454}
455EXPORT_SYMBOL_GPL(__devm_create_dev_dax);
456
457static int match_always_count;
458
459int __dax_driver_register(struct dax_device_driver *dax_drv,
460		struct module *module, const char *mod_name)
461{
462	struct device_driver *drv = &dax_drv->drv;
463	int rc = 0;
464
465	INIT_LIST_HEAD(&dax_drv->ids);
466	drv->owner = module;
467	drv->name = mod_name;
468	drv->mod_name = mod_name;
469	drv->bus = &dax_bus_type;
470
471	/* there can only be one default driver */
472	mutex_lock(&dax_bus_lock);
473	match_always_count += dax_drv->match_always;
474	if (match_always_count > 1) {
475		match_always_count--;
476		WARN_ON(1);
477		rc = -EINVAL;
478	}
479	mutex_unlock(&dax_bus_lock);
480	if (rc)
481		return rc;
482	return driver_register(drv);
483}
484EXPORT_SYMBOL_GPL(__dax_driver_register);
485
486void dax_driver_unregister(struct dax_device_driver *dax_drv)
487{
488	struct device_driver *drv = &dax_drv->drv;
489	struct dax_id *dax_id, *_id;
490
491	mutex_lock(&dax_bus_lock);
492	match_always_count -= dax_drv->match_always;
493	list_for_each_entry_safe(dax_id, _id, &dax_drv->ids, list) {
494		list_del(&dax_id->list);
495		kfree(dax_id);
496	}
497	mutex_unlock(&dax_bus_lock);
498	driver_unregister(drv);
499}
500EXPORT_SYMBOL_GPL(dax_driver_unregister);
501
502int __init dax_bus_init(void)
503{
504	int rc;
505
506	if (IS_ENABLED(CONFIG_DEV_DAX_PMEM_COMPAT)) {
507		dax_class = class_create(THIS_MODULE, "dax");
508		if (IS_ERR(dax_class))
509			return PTR_ERR(dax_class);
510	}
511
512	rc = bus_register(&dax_bus_type);
513	if (rc)
514		class_destroy(dax_class);
515	return rc;
516}
517
518void __exit dax_bus_exit(void)
519{
520	bus_unregister(&dax_bus_type);
521	class_destroy(dax_class);
522}