ntb_pingpong.c

  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, 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
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_setup(&pp->timer, pp_timer_func, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
288
289	return pp;
290}
291
292static 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
312static 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
330static 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
345static void pp_clear_ctx(struct pp_ctx *pp)
346{
347	ntb_link_disable(pp->ntb);
348
349	ntb_clear_ctx(pp->ntb);
350}
351
352static 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
361static void pp_clear_dbgfs(struct pp_ctx *pp)
362{
363	debugfs_remove_recursive(pp->dbgfs_dir);
364}
365
366static 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
394static 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
405static struct ntb_client pp_client = {
406	.ops = {
407		.probe = pp_probe,
408		.remove = pp_remove
409	}
410};
411
412static 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}
425module_init(pp_init);
426
427static void __exit pp_exit(void)
428{
429	ntb_unregister_client(&pp_client);
430	debugfs_remove_recursive(pp_dbgfs_topdir);
431}
432module_exit(pp_exit);