1 /*
2  *   This file is provided under a dual BSD/GPLv2 license.  When using or
3  *   redistributing this file, you may do so under either license.
4  *
5  *   GPL LICENSE SUMMARY
6  *
7  *   Copyright (C) 2015 EMC Corporation. All Rights Reserved.
8  *   Copyright (C) 2017 T-Platforms. All Rights Reserved.
9  *
10  *   This program is free software; you can redistribute it and/or modify
11  *   it under the terms of version 2 of the GNU General Public License as
12  *   published by the Free Software Foundation.
13  *
14  *   This program is distributed in the hope that it will be useful, but
15  *   WITHOUT ANY WARRANTY; without even the implied warranty of
16  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
17  *   General Public License for more details.
18  *
19  *   BSD LICENSE
20  *
21  *   Copyright (C) 2015 EMC Corporation. All Rights Reserved.
22  *   Copyright (C) 2017 T-Platforms. All Rights Reserved.
23  *
24  *   Redistribution and use in source and binary forms, with or without
25  *   modification, are permitted provided that the following conditions
26  *   are met:
27  *
28  *     * Redistributions of source code must retain the above copyright
29  *       notice, this list of conditions and the following disclaimer.
30  *     * Redistributions in binary form must reproduce the above copy
31  *       notice, this list of conditions and the following disclaimer in
32  *       the documentation and/or other materials provided with the
33  *       distribution.
34  *     * Neither the name of Intel Corporation nor the names of its
35  *       contributors may be used to endorse or promote products derived
36  *       from this software without specific prior written permission.
37  *
38  *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
39  *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
40  *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
41  *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
42  *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
43  *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
44  *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
45  *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
46  *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
47  *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
48  *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
49  *
50  * PCIe NTB Pingpong Linux driver
51  */
52 
53 /*
54  * How to use this tool, by example.
55  *
56  * Assuming $DBG_DIR is something like:
57  * '/sys/kernel/debug/ntb_perf/0000:00:03.0'
58  * Suppose aside from local device there is at least one remote device
59  * connected to NTB with index 0.
60  *-----------------------------------------------------------------------------
61  * Eg: install driver with specified delay between doorbell event and response
62  *
63  * root@self# insmod ntb_pingpong.ko delay_ms=1000
64  *-----------------------------------------------------------------------------
65  * Eg: get number of ping-pong cycles performed
66  *
67  * root@self# cat $DBG_DIR/count
68  */
69 
70 #include <linux/init.h>
71 #include <linux/kernel.h>
72 #include <linux/module.h>
73 #include <linux/device.h>
74 #include <linux/bitops.h>
75 
76 #include <linux/pci.h>
77 #include <linux/slab.h>
78 #include <linux/hrtimer.h>
79 #include <linux/debugfs.h>
80 
81 #include <linux/ntb.h>
82 
83 #define DRIVER_NAME		"ntb_pingpong"
84 #define DRIVER_VERSION		"2.0"
85 
86 MODULE_LICENSE("Dual BSD/GPL");
87 MODULE_VERSION(DRIVER_VERSION);
88 MODULE_AUTHOR("Allen Hubbe <Allen.Hubbe@emc.com>");
89 MODULE_DESCRIPTION("PCIe NTB Simple Pingpong Client");
90 
91 static unsigned int unsafe;
92 module_param(unsafe, uint, 0644);
93 MODULE_PARM_DESC(unsafe, "Run even though ntb operations may be unsafe");
94 
95 static unsigned int delay_ms = 1000;
96 module_param(delay_ms, uint, 0644);
97 MODULE_PARM_DESC(delay_ms, "Milliseconds to delay the response to peer");
98 
99 struct pp_ctx {
100 	struct ntb_dev *ntb;
101 	struct hrtimer timer;
102 	u64 in_db;
103 	u64 out_db;
104 	int out_pidx;
105 	u64 nmask;
106 	u64 pmask;
107 	atomic_t count;
108 	spinlock_t lock;
109 	struct dentry *dbgfs_dir;
110 };
111 #define to_pp_timer(__timer) \
112 	container_of(__timer, struct pp_ctx, timer)
113 
114 static struct dentry *pp_dbgfs_topdir;
115 
pp_find_next_peer(struct pp_ctx * pp)116 static int pp_find_next_peer(struct pp_ctx *pp)
117 {
118 	u64 link, out_db;
119 	int pidx;
120 
121 	link = ntb_link_is_up(pp->ntb, NULL, NULL);
122 
123 	/* Find next available peer */
124 	if (link & pp->nmask)
125 		pidx = __ffs64(link & pp->nmask);
126 	else if (link & pp->pmask)
127 		pidx = __ffs64(link & pp->pmask);
128 	else
129 		return -ENODEV;
130 
131 	out_db = BIT_ULL(ntb_peer_port_number(pp->ntb, pidx));
132 
133 	spin_lock(&pp->lock);
134 	pp->out_pidx = pidx;
135 	pp->out_db = out_db;
136 	spin_unlock(&pp->lock);
137 
138 	return 0;
139 }
140 
pp_setup(struct pp_ctx * pp)141 static void pp_setup(struct pp_ctx *pp)
142 {
143 	int ret;
144 
145 	ntb_db_set_mask(pp->ntb, pp->in_db);
146 
147 	hrtimer_cancel(&pp->timer);
148 
149 	ret = pp_find_next_peer(pp);
150 	if (ret == -ENODEV) {
151 		dev_dbg(&pp->ntb->dev, "Got no peers, so cancel\n");
152 		return;
153 	}
154 
155 	dev_dbg(&pp->ntb->dev, "Ping-pong started with port %d, db %#llx\n",
156 		ntb_peer_port_number(pp->ntb, pp->out_pidx), pp->out_db);
157 
158 	hrtimer_start(&pp->timer, ms_to_ktime(delay_ms), HRTIMER_MODE_REL);
159 }
160 
pp_clear(struct pp_ctx * pp)161 static void pp_clear(struct pp_ctx *pp)
162 {
163 	hrtimer_cancel(&pp->timer);
164 
165 	ntb_db_set_mask(pp->ntb, pp->in_db);
166 
167 	dev_dbg(&pp->ntb->dev, "Ping-pong cancelled\n");
168 }
169 
pp_ping(struct pp_ctx * pp)170 static void pp_ping(struct pp_ctx *pp)
171 {
172 	u32 count;
173 
174 	count = atomic_read(&pp->count);
175 
176 	spin_lock(&pp->lock);
177 	ntb_peer_spad_write(pp->ntb, pp->out_pidx, 0, count);
178 	ntb_peer_msg_write(pp->ntb, pp->out_pidx, 0, count);
179 
180 	dev_dbg(&pp->ntb->dev, "Ping port %d spad %#x, msg %#x\n",
181 		ntb_peer_port_number(pp->ntb, pp->out_pidx), count, count);
182 
183 	ntb_peer_db_set(pp->ntb, pp->out_db);
184 	ntb_db_clear_mask(pp->ntb, pp->in_db);
185 	spin_unlock(&pp->lock);
186 }
187 
pp_pong(struct pp_ctx * pp)188 static void pp_pong(struct pp_ctx *pp)
189 {
190 	u32 msg_data, spad_data;
191 	int pidx = 0;
192 
193 	/* Read pong data */
194 	spad_data = ntb_spad_read(pp->ntb, 0);
195 	msg_data = ntb_msg_read(pp->ntb, &pidx, 0);
196 	ntb_msg_clear_sts(pp->ntb, -1);
197 
198 	/*
199 	 * Scratchpad and message data may differ, since message register can't
200 	 * be rewritten unless status is cleared. Additionally either of them
201 	 * might be unsupported
202 	 */
203 	dev_dbg(&pp->ntb->dev, "Pong spad %#x, msg %#x (port %d)\n",
204 		spad_data, msg_data, ntb_peer_port_number(pp->ntb, pidx));
205 
206 	atomic_inc(&pp->count);
207 
208 	ntb_db_set_mask(pp->ntb, pp->in_db);
209 	ntb_db_clear(pp->ntb, pp->in_db);
210 
211 	hrtimer_start(&pp->timer, ms_to_ktime(delay_ms), HRTIMER_MODE_REL);
212 }
213 
pp_timer_func(struct hrtimer * t)214 static enum hrtimer_restart pp_timer_func(struct hrtimer *t)
215 {
216 	struct pp_ctx *pp = to_pp_timer(t);
217 
218 	pp_ping(pp);
219 
220 	return HRTIMER_NORESTART;
221 }
222 
pp_link_event(void * ctx)223 static void pp_link_event(void *ctx)
224 {
225 	struct pp_ctx *pp = ctx;
226 
227 	pp_setup(pp);
228 }
229 
pp_db_event(void * ctx,int vec)230 static void pp_db_event(void *ctx, int vec)
231 {
232 	struct pp_ctx *pp = ctx;
233 
234 	pp_pong(pp);
235 }
236 
237 static const struct ntb_ctx_ops pp_ops = {
238 	.link_event = pp_link_event,
239 	.db_event = pp_db_event
240 };
241 
pp_check_ntb(struct ntb_dev * ntb)242 static int pp_check_ntb(struct ntb_dev *ntb)
243 {
244 	u64 pmask;
245 
246 	if (ntb_db_is_unsafe(ntb)) {
247 		dev_dbg(&ntb->dev, "Doorbell is unsafe\n");
248 		if (!unsafe)
249 			return -EINVAL;
250 	}
251 
252 	if (ntb_spad_is_unsafe(ntb)) {
253 		dev_dbg(&ntb->dev, "Scratchpad is unsafe\n");
254 		if (!unsafe)
255 			return -EINVAL;
256 	}
257 
258 	pmask = GENMASK_ULL(ntb_peer_port_count(ntb), 0);
259 	if ((ntb_db_valid_mask(ntb) & pmask) != pmask) {
260 		dev_err(&ntb->dev, "Unsupported DB configuration\n");
261 		return -EINVAL;
262 	}
263 
264 	if (ntb_spad_count(ntb) < 1 && ntb_msg_count(ntb) < 1) {
265 		dev_err(&ntb->dev, "Scratchpads and messages unsupported\n");
266 		return -EINVAL;
267 	} else if (ntb_spad_count(ntb) < 1) {
268 		dev_dbg(&ntb->dev, "Scratchpads unsupported\n");
269 	} else if (ntb_msg_count(ntb) < 1) {
270 		dev_dbg(&ntb->dev, "Messages unsupported\n");
271 	}
272 
273 	return 0;
274 }
275 
pp_create_data(struct ntb_dev * ntb)276 static struct pp_ctx *pp_create_data(struct ntb_dev *ntb)
277 {
278 	struct pp_ctx *pp;
279 
280 	pp = devm_kzalloc(&ntb->dev, sizeof(*pp), GFP_KERNEL);
281 	if (!pp)
282 		return ERR_PTR(-ENOMEM);
283 
284 	pp->ntb = ntb;
285 	atomic_set(&pp->count, 0);
286 	spin_lock_init(&pp->lock);
287 	hrtimer_setup(&pp->timer, pp_timer_func, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
288 
289 	return pp;
290 }
291 
pp_init_flds(struct pp_ctx * pp)292 static void pp_init_flds(struct pp_ctx *pp)
293 {
294 	int pidx, lport, pcnt;
295 
296 	/* Find global port index */
297 	lport = ntb_port_number(pp->ntb);
298 	pcnt = ntb_peer_port_count(pp->ntb);
299 	for (pidx = 0; pidx < pcnt; pidx++) {
300 		if (lport < ntb_peer_port_number(pp->ntb, pidx))
301 			break;
302 	}
303 
304 	pp->in_db = BIT_ULL(lport);
305 	pp->pmask = GENMASK_ULL(pidx, 0) >> 1;
306 	pp->nmask = GENMASK_ULL(pcnt - 1, pidx);
307 
308 	dev_dbg(&pp->ntb->dev, "Inbound db %#llx, prev %#llx, next %#llx\n",
309 		pp->in_db, pp->pmask, pp->nmask);
310 }
311 
pp_mask_events(struct pp_ctx * pp)312 static int pp_mask_events(struct pp_ctx *pp)
313 {
314 	u64 db_mask, msg_mask;
315 	int ret;
316 
317 	db_mask = ntb_db_valid_mask(pp->ntb);
318 	ret = ntb_db_set_mask(pp->ntb, db_mask);
319 	if (ret)
320 		return ret;
321 
322 	/* Skip message events masking if unsupported */
323 	if (ntb_msg_count(pp->ntb) < 1)
324 		return 0;
325 
326 	msg_mask = ntb_msg_outbits(pp->ntb) | ntb_msg_inbits(pp->ntb);
327 	return ntb_msg_set_mask(pp->ntb, msg_mask);
328 }
329 
pp_setup_ctx(struct pp_ctx * pp)330 static int pp_setup_ctx(struct pp_ctx *pp)
331 {
332 	int ret;
333 
334 	ret = ntb_set_ctx(pp->ntb, pp, &pp_ops);
335 	if (ret)
336 		return ret;
337 
338 	ntb_link_enable(pp->ntb, NTB_SPEED_AUTO, NTB_WIDTH_AUTO);
339 	/* Might be not necessary */
340 	ntb_link_event(pp->ntb);
341 
342 	return 0;
343 }
344 
pp_clear_ctx(struct pp_ctx * pp)345 static void pp_clear_ctx(struct pp_ctx *pp)
346 {
347 	ntb_link_disable(pp->ntb);
348 
349 	ntb_clear_ctx(pp->ntb);
350 }
351 
pp_setup_dbgfs(struct pp_ctx * pp)352 static void pp_setup_dbgfs(struct pp_ctx *pp)
353 {
354 	struct pci_dev *pdev = pp->ntb->pdev;
355 
356 	pp->dbgfs_dir = debugfs_create_dir(pci_name(pdev), pp_dbgfs_topdir);
357 
358 	debugfs_create_atomic_t("count", 0600, pp->dbgfs_dir, &pp->count);
359 }
360 
pp_clear_dbgfs(struct pp_ctx * pp)361 static void pp_clear_dbgfs(struct pp_ctx *pp)
362 {
363 	debugfs_remove_recursive(pp->dbgfs_dir);
364 }
365 
pp_probe(struct ntb_client * client,struct ntb_dev * ntb)366 static int pp_probe(struct ntb_client *client, struct ntb_dev *ntb)
367 {
368 	struct pp_ctx *pp;
369 	int ret;
370 
371 	ret = pp_check_ntb(ntb);
372 	if (ret)
373 		return ret;
374 
375 	pp = pp_create_data(ntb);
376 	if (IS_ERR(pp))
377 		return PTR_ERR(pp);
378 
379 	pp_init_flds(pp);
380 
381 	ret = pp_mask_events(pp);
382 	if (ret)
383 		return ret;
384 
385 	ret = pp_setup_ctx(pp);
386 	if (ret)
387 		return ret;
388 
389 	pp_setup_dbgfs(pp);
390 
391 	return 0;
392 }
393 
pp_remove(struct ntb_client * client,struct ntb_dev * ntb)394 static void pp_remove(struct ntb_client *client, struct ntb_dev *ntb)
395 {
396 	struct pp_ctx *pp = ntb->ctx;
397 
398 	pp_clear_dbgfs(pp);
399 
400 	pp_clear_ctx(pp);
401 
402 	pp_clear(pp);
403 }
404 
405 static struct ntb_client pp_client = {
406 	.ops = {
407 		.probe = pp_probe,
408 		.remove = pp_remove
409 	}
410 };
411 
pp_init(void)412 static int __init pp_init(void)
413 {
414 	int ret;
415 
416 	if (debugfs_initialized())
417 		pp_dbgfs_topdir = debugfs_create_dir(KBUILD_MODNAME, NULL);
418 
419 	ret = ntb_register_client(&pp_client);
420 	if (ret)
421 		debugfs_remove_recursive(pp_dbgfs_topdir);
422 
423 	return ret;
424 }
425 module_init(pp_init);
426 
pp_exit(void)427 static void __exit pp_exit(void)
428 {
429 	ntb_unregister_client(&pp_client);
430 	debugfs_remove_recursive(pp_dbgfs_topdir);
431 }
432 module_exit(pp_exit);
433