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 
16 static DEFINE_IDA(fpga_bridge_ida);
17 static const struct class fpga_bridge_class;
18 
19 /* Lock for adding/removing bridges to linked lists*/
20 static 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  */
fpga_bridge_enable(struct fpga_bridge * bridge)29 int fpga_bridge_enable(struct fpga_bridge *bridge)
30 {
31 	dev_dbg(&bridge->dev, "enable\n");
32 
33 	if (bridge->br_ops && bridge->br_ops->enable_set)
34 		return bridge->br_ops->enable_set(bridge, 1);
35 
36 	return 0;
37 }
38 EXPORT_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  */
fpga_bridge_disable(struct fpga_bridge * bridge)47 int fpga_bridge_disable(struct fpga_bridge *bridge)
48 {
49 	dev_dbg(&bridge->dev, "disable\n");
50 
51 	if (bridge->br_ops && bridge->br_ops->enable_set)
52 		return bridge->br_ops->enable_set(bridge, 0);
53 
54 	return 0;
55 }
56 EXPORT_SYMBOL_GPL(fpga_bridge_disable);
57 
__fpga_bridge_get(struct device * dev,struct fpga_image_info * info)58 static 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 
80 err_ll_mod:
81 	mutex_unlock(&bridge->mutex);
82 err_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  */
of_fpga_bridge_get(struct device_node * np,struct fpga_image_info * info)98 struct 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 }
109 EXPORT_SYMBOL_GPL(of_fpga_bridge_get);
110 
fpga_bridge_dev_match(struct device * dev,const void * data)111 static 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  */
fpga_bridge_get(struct device * dev,struct fpga_image_info * info)125 struct 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 }
137 EXPORT_SYMBOL_GPL(fpga_bridge_get);
138 
139 /**
140  * fpga_bridge_put - release a reference to a bridge
141  *
142  * @bridge: FPGA bridge
143  */
fpga_bridge_put(struct fpga_bridge * bridge)144 void 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 }
153 EXPORT_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  */
fpga_bridges_enable(struct list_head * bridge_list)163 int 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 }
176 EXPORT_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  */
fpga_bridges_disable(struct list_head * bridge_list)187 int 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 }
200 EXPORT_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  */
fpga_bridges_put(struct list_head * bridge_list)210 void 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 }
223 EXPORT_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  */
of_fpga_bridge_get_to_list(struct device_node * np,struct fpga_image_info * info,struct list_head * bridge_list)236 int 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 }
253 EXPORT_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  */
fpga_bridge_get_to_list(struct device * dev,struct fpga_image_info * info,struct list_head * bridge_list)266 int 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 }
283 EXPORT_SYMBOL_GPL(fpga_bridge_get_to_list);
284 
name_show(struct device * dev,struct device_attribute * attr,char * buf)285 static 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 
state_show(struct device * dev,struct device_attribute * attr,char * buf)293 static 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 && 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 
308 static DEVICE_ATTR_RO(name);
309 static DEVICE_ATTR_RO(state);
310 
311 static struct attribute *fpga_bridge_attrs[] = {
312 	&dev_attr_name.attr,
313 	&dev_attr_state.attr,
314 	NULL,
315 };
316 ATTRIBUTE_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  */
327 struct fpga_bridge *
fpga_bridge_register(struct device * parent,const char * name,const struct fpga_bridge_ops * br_ops,void * priv)328 fpga_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 
382 error_device:
383 	ida_free(&fpga_bridge_ida, id);
384 error_kfree:
385 	kfree(bridge);
386 
387 	return ERR_PTR(ret);
388 }
389 EXPORT_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  */
fpga_bridge_unregister(struct fpga_bridge * bridge)398 void 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 && bridge->br_ops->fpga_bridge_remove)
405 		bridge->br_ops->fpga_bridge_remove(bridge);
406 
407 	device_unregister(&bridge->dev);
408 }
409 EXPORT_SYMBOL_GPL(fpga_bridge_unregister);
410 
fpga_bridge_dev_release(struct device * dev)411 static 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 
419 static 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 
fpga_bridge_dev_init(void)425 static int __init fpga_bridge_dev_init(void)
426 {
427 	return class_register(&fpga_bridge_class);
428 }
429 
fpga_bridge_dev_exit(void)430 static void __exit fpga_bridge_dev_exit(void)
431 {
432 	class_unregister(&fpga_bridge_class);
433 	ida_destroy(&fpga_bridge_ida);
434 }
435 
436 MODULE_DESCRIPTION("FPGA Bridge Driver");
437 MODULE_AUTHOR("Alan Tull <atull@kernel.org>");
438 MODULE_LICENSE("GPL v2");
439 
440 subsys_initcall(fpga_bridge_dev_init);
441 module_exit(fpga_bridge_dev_exit);
442