1// SPDX-License-Identifier: GPL-2.0
2/*
3 * FPGA Bridge Framework Driver
4 *
5 *  Copyright (C) 2013-2016 Altera Corporation, All Rights Reserved.
6 *  Copyright (C) 2017 Intel Corporation
7 */
8#include <linux/fpga/fpga-bridge.h>
9#include <linux/idr.h>
10#include <linux/kernel.h>
11#include <linux/module.h>
12#include <linux/of_platform.h>
13#include <linux/slab.h>
14#include <linux/spinlock.h>
15
16static DEFINE_IDA(fpga_bridge_ida);
17static const struct class fpga_bridge_class;
18
19/* Lock for adding/removing bridges to linked lists*/
20static DEFINE_SPINLOCK(bridge_list_lock);
21
22/**
23 * fpga_bridge_enable - Enable transactions on the bridge
24 *
25 * @bridge: FPGA bridge
26 *
27 * Return: 0 for success, error code otherwise.
28 */
29int fpga_bridge_enable(struct fpga_bridge *bridge)
30{
31	dev_dbg(&bridge->dev, "enable\n");
32
33	if (bridge->br_ops->enable_set)
34		return bridge->br_ops->enable_set(bridge, 1);
35
36	return 0;
37}
38EXPORT_SYMBOL_GPL(fpga_bridge_enable);
39
40/**
41 * fpga_bridge_disable - Disable transactions on the bridge
42 *
43 * @bridge: FPGA bridge
44 *
45 * Return: 0 for success, error code otherwise.
46 */
47int fpga_bridge_disable(struct fpga_bridge *bridge)
48{
49	dev_dbg(&bridge->dev, "disable\n");
50
51	if (bridge->br_ops->enable_set)
52		return bridge->br_ops->enable_set(bridge, 0);
53
54	return 0;
55}
56EXPORT_SYMBOL_GPL(fpga_bridge_disable);
57
58static struct fpga_bridge *__fpga_bridge_get(struct device *dev,
59					     struct fpga_image_info *info)
60{
61	struct fpga_bridge *bridge;
62	int ret = -ENODEV;
63
64	bridge = to_fpga_bridge(dev);
65
66	bridge->info = info;
67
68	if (!mutex_trylock(&bridge->mutex)) {
69		ret = -EBUSY;
70		goto err_dev;
71	}
72
73	if (!try_module_get(dev->parent->driver->owner))
74		goto err_ll_mod;
75
76	dev_dbg(&bridge->dev, "get\n");
77
78	return bridge;
79
80err_ll_mod:
81	mutex_unlock(&bridge->mutex);
82err_dev:
83	put_device(dev);
84	return ERR_PTR(ret);
85}
86
87/**
88 * of_fpga_bridge_get - get an exclusive reference to an fpga bridge
89 *
90 * @np: node pointer of an FPGA bridge.
91 * @info: fpga image specific information.
92 *
93 * Return:
94 * * fpga_bridge struct pointer if successful.
95 * * -EBUSY if someone already has a reference to the bridge.
96 * * -ENODEV if @np is not an FPGA Bridge or can't take parent driver refcount.
97 */
98struct fpga_bridge *of_fpga_bridge_get(struct device_node *np,
99				       struct fpga_image_info *info)
100{
101	struct device *dev;
102
103	dev = class_find_device_by_of_node(&fpga_bridge_class, np);
104	if (!dev)
105		return ERR_PTR(-ENODEV);
106
107	return __fpga_bridge_get(dev, info);
108}
109EXPORT_SYMBOL_GPL(of_fpga_bridge_get);
110
111static int fpga_bridge_dev_match(struct device *dev, const void *data)
112{
113	return dev->parent == data;
114}
115
116/**
117 * fpga_bridge_get - get an exclusive reference to an fpga bridge
118 * @dev:	parent device that fpga bridge was registered with
119 * @info:	fpga image specific information
120 *
121 * Given a device, get an exclusive reference to an fpga bridge.
122 *
123 * Return: fpga bridge struct or IS_ERR() condition containing error code.
124 */
125struct fpga_bridge *fpga_bridge_get(struct device *dev,
126				    struct fpga_image_info *info)
127{
128	struct device *bridge_dev;
129
130	bridge_dev = class_find_device(&fpga_bridge_class, NULL, dev,
131				       fpga_bridge_dev_match);
132	if (!bridge_dev)
133		return ERR_PTR(-ENODEV);
134
135	return __fpga_bridge_get(bridge_dev, info);
136}
137EXPORT_SYMBOL_GPL(fpga_bridge_get);
138
139/**
140 * fpga_bridge_put - release a reference to a bridge
141 *
142 * @bridge: FPGA bridge
143 */
144void fpga_bridge_put(struct fpga_bridge *bridge)
145{
146	dev_dbg(&bridge->dev, "put\n");
147
148	bridge->info = NULL;
149	module_put(bridge->dev.parent->driver->owner);
150	mutex_unlock(&bridge->mutex);
151	put_device(&bridge->dev);
152}
153EXPORT_SYMBOL_GPL(fpga_bridge_put);
154
155/**
156 * fpga_bridges_enable - enable bridges in a list
157 * @bridge_list: list of FPGA bridges
158 *
159 * Enable each bridge in the list. If list is empty, do nothing.
160 *
161 * Return: 0 for success or empty bridge list or an error code otherwise.
162 */
163int fpga_bridges_enable(struct list_head *bridge_list)
164{
165	struct fpga_bridge *bridge;
166	int ret;
167
168	list_for_each_entry(bridge, bridge_list, node) {
169		ret = fpga_bridge_enable(bridge);
170		if (ret)
171			return ret;
172	}
173
174	return 0;
175}
176EXPORT_SYMBOL_GPL(fpga_bridges_enable);
177
178/**
179 * fpga_bridges_disable - disable bridges in a list
180 *
181 * @bridge_list: list of FPGA bridges
182 *
183 * Disable each bridge in the list. If list is empty, do nothing.
184 *
185 * Return: 0 for success or empty bridge list or an error code otherwise.
186 */
187int fpga_bridges_disable(struct list_head *bridge_list)
188{
189	struct fpga_bridge *bridge;
190	int ret;
191
192	list_for_each_entry(bridge, bridge_list, node) {
193		ret = fpga_bridge_disable(bridge);
194		if (ret)
195			return ret;
196	}
197
198	return 0;
199}
200EXPORT_SYMBOL_GPL(fpga_bridges_disable);
201
202/**
203 * fpga_bridges_put - put bridges
204 *
205 * @bridge_list: list of FPGA bridges
206 *
207 * For each bridge in the list, put the bridge and remove it from the list.
208 * If list is empty, do nothing.
209 */
210void fpga_bridges_put(struct list_head *bridge_list)
211{
212	struct fpga_bridge *bridge, *next;
213	unsigned long flags;
214
215	list_for_each_entry_safe(bridge, next, bridge_list, node) {
216		fpga_bridge_put(bridge);
217
218		spin_lock_irqsave(&bridge_list_lock, flags);
219		list_del(&bridge->node);
220		spin_unlock_irqrestore(&bridge_list_lock, flags);
221	}
222}
223EXPORT_SYMBOL_GPL(fpga_bridges_put);
224
225/**
226 * of_fpga_bridge_get_to_list - get a bridge, add it to a list
227 *
228 * @np: node pointer of an FPGA bridge
229 * @info: fpga image specific information
230 * @bridge_list: list of FPGA bridges
231 *
232 * Get an exclusive reference to the bridge and it to the list.
233 *
234 * Return: 0 for success, error code from of_fpga_bridge_get() otherwise.
235 */
236int of_fpga_bridge_get_to_list(struct device_node *np,
237			       struct fpga_image_info *info,
238			       struct list_head *bridge_list)
239{
240	struct fpga_bridge *bridge;
241	unsigned long flags;
242
243	bridge = of_fpga_bridge_get(np, info);
244	if (IS_ERR(bridge))
245		return PTR_ERR(bridge);
246
247	spin_lock_irqsave(&bridge_list_lock, flags);
248	list_add(&bridge->node, bridge_list);
249	spin_unlock_irqrestore(&bridge_list_lock, flags);
250
251	return 0;
252}
253EXPORT_SYMBOL_GPL(of_fpga_bridge_get_to_list);
254
255/**
256 * fpga_bridge_get_to_list - given device, get a bridge, add it to a list
257 *
258 * @dev: FPGA bridge device
259 * @info: fpga image specific information
260 * @bridge_list: list of FPGA bridges
261 *
262 * Get an exclusive reference to the bridge and it to the list.
263 *
264 * Return: 0 for success, error code from fpga_bridge_get() otherwise.
265 */
266int fpga_bridge_get_to_list(struct device *dev,
267			    struct fpga_image_info *info,
268			    struct list_head *bridge_list)
269{
270	struct fpga_bridge *bridge;
271	unsigned long flags;
272
273	bridge = fpga_bridge_get(dev, info);
274	if (IS_ERR(bridge))
275		return PTR_ERR(bridge);
276
277	spin_lock_irqsave(&bridge_list_lock, flags);
278	list_add(&bridge->node, bridge_list);
279	spin_unlock_irqrestore(&bridge_list_lock, flags);
280
281	return 0;
282}
283EXPORT_SYMBOL_GPL(fpga_bridge_get_to_list);
284
285static ssize_t name_show(struct device *dev,
286			 struct device_attribute *attr, char *buf)
287{
288	struct fpga_bridge *bridge = to_fpga_bridge(dev);
289
290	return sprintf(buf, "%s\n", bridge->name);
291}
292
293static ssize_t state_show(struct device *dev,
294			  struct device_attribute *attr, char *buf)
295{
296	struct fpga_bridge *bridge = to_fpga_bridge(dev);
297	int state = 1;
298
299	if (bridge->br_ops->enable_show) {
300		state = bridge->br_ops->enable_show(bridge);
301		if (state < 0)
302			return state;
303	}
304
305	return sysfs_emit(buf, "%s\n", state ? "enabled" : "disabled");
306}
307
308static DEVICE_ATTR_RO(name);
309static DEVICE_ATTR_RO(state);
310
311static struct attribute *fpga_bridge_attrs[] = {
312	&dev_attr_name.attr,
313	&dev_attr_state.attr,
314	NULL,
315};
316ATTRIBUTE_GROUPS(fpga_bridge);
317
318/**
319 * fpga_bridge_register - create and register an FPGA Bridge device
320 * @parent:	FPGA bridge device from pdev
321 * @name:	FPGA bridge name
322 * @br_ops:	pointer to structure of fpga bridge ops
323 * @priv:	FPGA bridge private data
324 *
325 * Return: struct fpga_bridge pointer or ERR_PTR()
326 */
327struct fpga_bridge *
328fpga_bridge_register(struct device *parent, const char *name,
329		     const struct fpga_bridge_ops *br_ops,
330		     void *priv)
331{
332	struct fpga_bridge *bridge;
333	int id, ret;
334
335	if (!br_ops) {
336		dev_err(parent, "Attempt to register without fpga_bridge_ops\n");
337		return ERR_PTR(-EINVAL);
338	}
339
340	if (!name || !strlen(name)) {
341		dev_err(parent, "Attempt to register with no name!\n");
342		return ERR_PTR(-EINVAL);
343	}
344
345	bridge = kzalloc(sizeof(*bridge), GFP_KERNEL);
346	if (!bridge)
347		return ERR_PTR(-ENOMEM);
348
349	id = ida_alloc(&fpga_bridge_ida, GFP_KERNEL);
350	if (id < 0) {
351		ret = id;
352		goto error_kfree;
353	}
354
355	mutex_init(&bridge->mutex);
356	INIT_LIST_HEAD(&bridge->node);
357
358	bridge->name = name;
359	bridge->br_ops = br_ops;
360	bridge->priv = priv;
361
362	bridge->dev.groups = br_ops->groups;
363	bridge->dev.class = &fpga_bridge_class;
364	bridge->dev.parent = parent;
365	bridge->dev.of_node = parent->of_node;
366	bridge->dev.id = id;
367
368	ret = dev_set_name(&bridge->dev, "br%d", id);
369	if (ret)
370		goto error_device;
371
372	ret = device_register(&bridge->dev);
373	if (ret) {
374		put_device(&bridge->dev);
375		return ERR_PTR(ret);
376	}
377
378	of_platform_populate(bridge->dev.of_node, NULL, NULL, &bridge->dev);
379
380	return bridge;
381
382error_device:
383	ida_free(&fpga_bridge_ida, id);
384error_kfree:
385	kfree(bridge);
386
387	return ERR_PTR(ret);
388}
389EXPORT_SYMBOL_GPL(fpga_bridge_register);
390
391/**
392 * fpga_bridge_unregister - unregister an FPGA bridge
393 *
394 * @bridge: FPGA bridge struct
395 *
396 * This function is intended for use in an FPGA bridge driver's remove function.
397 */
398void fpga_bridge_unregister(struct fpga_bridge *bridge)
399{
400	/*
401	 * If the low level driver provides a method for putting bridge into
402	 * a desired state upon unregister, do it.
403	 */
404	if (bridge->br_ops->fpga_bridge_remove)
405		bridge->br_ops->fpga_bridge_remove(bridge);
406
407	device_unregister(&bridge->dev);
408}
409EXPORT_SYMBOL_GPL(fpga_bridge_unregister);
410
411static void fpga_bridge_dev_release(struct device *dev)
412{
413	struct fpga_bridge *bridge = to_fpga_bridge(dev);
414
415	ida_free(&fpga_bridge_ida, bridge->dev.id);
416	kfree(bridge);
417}
418
419static const struct class fpga_bridge_class = {
420	.name = "fpga_bridge",
421	.dev_groups = fpga_bridge_groups,
422	.dev_release = fpga_bridge_dev_release,
423};
424
425static int __init fpga_bridge_dev_init(void)
426{
427	return class_register(&fpga_bridge_class);
428}
429
430static void __exit fpga_bridge_dev_exit(void)
431{
432	class_unregister(&fpga_bridge_class);
433	ida_destroy(&fpga_bridge_ida);
434}
435
436MODULE_DESCRIPTION("FPGA Bridge Driver");
437MODULE_AUTHOR("Alan Tull <atull@kernel.org>");
438MODULE_LICENSE("GPL v2");
439
440subsys_initcall(fpga_bridge_dev_init);
441module_exit(fpga_bridge_dev_exit);
442