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
86MODULE_LICENSE("Dual BSD/GPL");
87MODULE_VERSION(DRIVER_VERSION);
88MODULE_AUTHOR("Allen Hubbe <Allen.Hubbe@emc.com>");
89MODULE_DESCRIPTION("PCIe NTB Simple Pingpong Client");
90
91static unsigned int unsafe;
92module_param(unsafe, uint, 0644);
93MODULE_PARM_DESC(unsafe, "Run even though ntb operations may be unsafe");
94
95static unsigned int delay_ms = 1000;
96module_param(delay_ms, uint, 0644);
97MODULE_PARM_DESC(delay_ms, "Milliseconds to delay the response to peer");
98
99struct 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
114static struct dentry *pp_dbgfs_topdir;
115
116static 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
141static 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
161static 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
170static 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
188static void pp_pong(struct pp_ctx *pp)
189{
190	u32 msg_data = -1, spad_data = -1;
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
214static 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
223static void pp_link_event(void *ctx)
224{
225	struct pp_ctx *pp = ctx;
226
227	pp_setup(pp);
228}
229
230static void pp_db_event(void *ctx, int vec)
231{
232	struct pp_ctx *pp = ctx;
233
234	pp_pong(pp);
235}
236
237static const struct ntb_ctx_ops pp_ops = {
238	.link_event = pp_link_event,
239	.db_event = pp_db_event
240};
241
242static 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
276static 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_init(&pp->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
288	pp->timer.function = pp_timer_func;
289
290	return pp;
291}
292
293static void pp_init_flds(struct pp_ctx *pp)
294{
295	int pidx, lport, pcnt;
296
297	/* Find global port index */
298	lport = ntb_port_number(pp->ntb);
299	pcnt = ntb_peer_port_count(pp->ntb);
300	for (pidx = 0; pidx < pcnt; pidx++) {
301		if (lport < ntb_peer_port_number(pp->ntb, pidx))
302			break;
303	}
304
305	pp->in_db = BIT_ULL(lport);
306	pp->pmask = GENMASK_ULL(pidx, 0) >> 1;
307	pp->nmask = GENMASK_ULL(pcnt - 1, pidx);
308
309	dev_dbg(&pp->ntb->dev, "Inbound db %#llx, prev %#llx, next %#llx\n",
310		pp->in_db, pp->pmask, pp->nmask);
311}
312
313static int pp_mask_events(struct pp_ctx *pp)
314{
315	u64 db_mask, msg_mask;
316	int ret;
317
318	db_mask = ntb_db_valid_mask(pp->ntb);
319	ret = ntb_db_set_mask(pp->ntb, db_mask);
320	if (ret)
321		return ret;
322
323	/* Skip message events masking if unsupported */
324	if (ntb_msg_count(pp->ntb) < 1)
325		return 0;
326
327	msg_mask = ntb_msg_outbits(pp->ntb) | ntb_msg_inbits(pp->ntb);
328	return ntb_msg_set_mask(pp->ntb, msg_mask);
329}
330
331static int pp_setup_ctx(struct pp_ctx *pp)
332{
333	int ret;
334
335	ret = ntb_set_ctx(pp->ntb, pp, &pp_ops);
336	if (ret)
337		return ret;
338
339	ntb_link_enable(pp->ntb, NTB_SPEED_AUTO, NTB_WIDTH_AUTO);
340	/* Might be not necessary */
341	ntb_link_event(pp->ntb);
342
343	return 0;
344}
345
346static void pp_clear_ctx(struct pp_ctx *pp)
347{
348	ntb_link_disable(pp->ntb);
349
350	ntb_clear_ctx(pp->ntb);
351}
352
353static void pp_setup_dbgfs(struct pp_ctx *pp)
354{
355	struct pci_dev *pdev = pp->ntb->pdev;
356
357	pp->dbgfs_dir = debugfs_create_dir(pci_name(pdev), pp_dbgfs_topdir);
358
359	debugfs_create_atomic_t("count", 0600, pp->dbgfs_dir, &pp->count);
360}
361
362static void pp_clear_dbgfs(struct pp_ctx *pp)
363{
364	debugfs_remove_recursive(pp->dbgfs_dir);
365}
366
367static int pp_probe(struct ntb_client *client, struct ntb_dev *ntb)
368{
369	struct pp_ctx *pp;
370	int ret;
371
372	ret = pp_check_ntb(ntb);
373	if (ret)
374		return ret;
375
376	pp = pp_create_data(ntb);
377	if (IS_ERR(pp))
378		return PTR_ERR(pp);
379
380	pp_init_flds(pp);
381
382	ret = pp_mask_events(pp);
383	if (ret)
384		return ret;
385
386	ret = pp_setup_ctx(pp);
387	if (ret)
388		return ret;
389
390	pp_setup_dbgfs(pp);
391
392	return 0;
393}
394
395static void pp_remove(struct ntb_client *client, struct ntb_dev *ntb)
396{
397	struct pp_ctx *pp = ntb->ctx;
398
399	pp_clear_dbgfs(pp);
400
401	pp_clear_ctx(pp);
402
403	pp_clear(pp);
404}
405
406static struct ntb_client pp_client = {
407	.ops = {
408		.probe = pp_probe,
409		.remove = pp_remove
410	}
411};
412
413static int __init pp_init(void)
414{
415	int ret;
416
417	if (debugfs_initialized())
418		pp_dbgfs_topdir = debugfs_create_dir(KBUILD_MODNAME, NULL);
419
420	ret = ntb_register_client(&pp_client);
421	if (ret)
422		debugfs_remove_recursive(pp_dbgfs_topdir);
423
424	return ret;
425}
426module_init(pp_init);
427
428static void __exit pp_exit(void)
429{
430	ntb_unregister_client(&pp_client);
431	debugfs_remove_recursive(pp_dbgfs_topdir);
432}
433module_exit(pp_exit);
434