xref: /freebsd/sys/dev/ntb/ntb_transport.c (revision 2c8d04d0228871c24017509cf039e7c5d97d97be)
1 /*-
2  * Copyright (c) 2016 Alexander Motin <mav@FreeBSD.org>
3  * Copyright (C) 2013 Intel Corporation
4  * Copyright (C) 2015 EMC Corporation
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  *
16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26  * SUCH DAMAGE.
27  */
28 
29 /*
30  * The Non-Transparent Bridge (NTB) is a device that allows you to connect
31  * two or more systems using a PCI-e links, providing remote memory access.
32  *
33  * This module contains a transport for sending and receiving messages by
34  * writing to remote memory window(s) provided by underlying NTB device.
35  *
36  * NOTE: Much of the code in this module is shared with Linux. Any patches may
37  * be picked up and redistributed in Linux with a dual GPL/BSD license.
38  */
39 
40 #include <sys/cdefs.h>
41 __FBSDID("$FreeBSD$");
42 
43 #include <sys/param.h>
44 #include <sys/kernel.h>
45 #include <sys/systm.h>
46 #include <sys/bitset.h>
47 #include <sys/bus.h>
48 #include <sys/ktr.h>
49 #include <sys/limits.h>
50 #include <sys/lock.h>
51 #include <sys/malloc.h>
52 #include <sys/mbuf.h>
53 #include <sys/module.h>
54 #include <sys/mutex.h>
55 #include <sys/queue.h>
56 #include <sys/sysctl.h>
57 #include <sys/taskqueue.h>
58 
59 #include <vm/vm.h>
60 #include <vm/pmap.h>
61 
62 #include <machine/bus.h>
63 
64 #include "ntb.h"
65 #include "ntb_transport.h"
66 
67 #define QP_SETSIZE	64
68 BITSET_DEFINE(_qpset, QP_SETSIZE);
69 #define test_bit(pos, addr)	BIT_ISSET(QP_SETSIZE, (pos), (addr))
70 #define set_bit(pos, addr)	BIT_SET(QP_SETSIZE, (pos), (addr))
71 #define clear_bit(pos, addr)	BIT_CLR(QP_SETSIZE, (pos), (addr))
72 #define ffs_bit(addr)		BIT_FFS(QP_SETSIZE, (addr))
73 
74 #define KTR_NTB KTR_SPARE3
75 
76 #define NTB_TRANSPORT_VERSION	4
77 
78 static SYSCTL_NODE(_hw, OID_AUTO, ntb_transport, CTLFLAG_RW, 0, "ntb_transport");
79 
80 static unsigned g_ntb_transport_debug_level;
81 SYSCTL_UINT(_hw_ntb_transport, OID_AUTO, debug_level, CTLFLAG_RWTUN,
82     &g_ntb_transport_debug_level, 0,
83     "ntb_transport log level -- higher is more verbose");
84 #define ntb_printf(lvl, ...) do {			\
85 	if ((lvl) <= g_ntb_transport_debug_level) {	\
86 		printf(__VA_ARGS__);			\
87 	}						\
88 } while (0)
89 
90 static unsigned transport_mtu = 0x10000;
91 
92 static uint64_t max_mw_size;
93 SYSCTL_UQUAD(_hw_ntb_transport, OID_AUTO, max_mw_size, CTLFLAG_RDTUN, &max_mw_size, 0,
94     "If enabled (non-zero), limit the size of large memory windows. "
95     "Both sides of the NTB MUST set the same value here.");
96 
97 static unsigned max_num_clients;
98 SYSCTL_UINT(_hw_ntb_transport, OID_AUTO, max_num_clients, CTLFLAG_RDTUN,
99     &max_num_clients, 0, "Maximum number of NTB transport clients.  "
100     "0 (default) - use all available NTB memory windows; "
101     "positive integer N - Limit to N memory windows.");
102 
103 static unsigned enable_xeon_watchdog;
104 SYSCTL_UINT(_hw_ntb_transport, OID_AUTO, enable_xeon_watchdog, CTLFLAG_RDTUN,
105     &enable_xeon_watchdog, 0, "If non-zero, write a register every second to "
106     "keep a watchdog from tearing down the NTB link");
107 
108 STAILQ_HEAD(ntb_queue_list, ntb_queue_entry);
109 
110 typedef uint32_t ntb_q_idx_t;
111 
112 struct ntb_queue_entry {
113 	/* ntb_queue list reference */
114 	STAILQ_ENTRY(ntb_queue_entry) entry;
115 
116 	/* info on data to be transferred */
117 	void		*cb_data;
118 	void		*buf;
119 	uint32_t	len;
120 	uint32_t	flags;
121 
122 	struct ntb_transport_qp		*qp;
123 	struct ntb_payload_header	*x_hdr;
124 	ntb_q_idx_t	index;
125 };
126 
127 struct ntb_rx_info {
128 	ntb_q_idx_t	entry;
129 };
130 
131 struct ntb_transport_qp {
132 	struct ntb_transport_ctx	*transport;
133 	device_t		 ntb;
134 
135 	void			*cb_data;
136 
137 	bool			client_ready;
138 	volatile bool		link_is_up;
139 	uint8_t			qp_num;	/* Only 64 QPs are allowed.  0-63 */
140 
141 	struct ntb_rx_info	*rx_info;
142 	struct ntb_rx_info	*remote_rx_info;
143 
144 	void (*tx_handler)(struct ntb_transport_qp *qp, void *qp_data,
145 	    void *data, int len);
146 	struct ntb_queue_list	tx_free_q;
147 	struct mtx		ntb_tx_free_q_lock;
148 	caddr_t			tx_mw;
149 	bus_addr_t		tx_mw_phys;
150 	ntb_q_idx_t		tx_index;
151 	ntb_q_idx_t		tx_max_entry;
152 	uint64_t		tx_max_frame;
153 
154 	void (*rx_handler)(struct ntb_transport_qp *qp, void *qp_data,
155 	    void *data, int len);
156 	struct ntb_queue_list	rx_post_q;
157 	struct ntb_queue_list	rx_pend_q;
158 	/* ntb_rx_q_lock: synchronize access to rx_XXXX_q */
159 	struct mtx		ntb_rx_q_lock;
160 	struct task		rxc_db_work;
161 	struct taskqueue	*rxc_tq;
162 	caddr_t			rx_buff;
163 	ntb_q_idx_t		rx_index;
164 	ntb_q_idx_t		rx_max_entry;
165 	uint64_t		rx_max_frame;
166 
167 	void (*event_handler)(void *data, enum ntb_link_event status);
168 	struct callout		link_work;
169 	struct callout		rx_full;
170 
171 	uint64_t		last_rx_no_buf;
172 
173 	/* Stats */
174 	uint64_t		rx_bytes;
175 	uint64_t		rx_pkts;
176 	uint64_t		rx_ring_empty;
177 	uint64_t		rx_err_no_buf;
178 	uint64_t		rx_err_oflow;
179 	uint64_t		rx_err_ver;
180 	uint64_t		tx_bytes;
181 	uint64_t		tx_pkts;
182 	uint64_t		tx_ring_full;
183 	uint64_t		tx_err_no_buf;
184 
185 	struct mtx		tx_lock;
186 };
187 
188 struct ntb_transport_mw {
189 	vm_paddr_t	phys_addr;
190 	size_t		phys_size;
191 	size_t		xlat_align;
192 	size_t		xlat_align_size;
193 	bus_addr_t	addr_limit;
194 	/* Tx buff is off vbase / phys_addr */
195 	caddr_t		vbase;
196 	size_t		xlat_size;
197 	size_t		buff_size;
198 	/* Rx buff is off virt_addr / dma_addr */
199 	caddr_t		virt_addr;
200 	bus_addr_t	dma_addr;
201 };
202 
203 struct ntb_transport_ctx {
204 	device_t		 dev;
205 	device_t		 ntb;
206 	struct ntb_transport_mw	*mw_vec;
207 	struct ntb_transport_qp	*qp_vec;
208 	struct _qpset		qp_bitmap;
209 	struct _qpset		qp_bitmap_free;
210 	unsigned		mw_count;
211 	unsigned		qp_count;
212 	volatile bool		link_is_up;
213 	struct callout		link_work;
214 	struct callout		link_watchdog;
215 	struct task		link_cleanup;
216 };
217 
218 enum {
219 	NTBT_DESC_DONE_FLAG = 1 << 0,
220 	NTBT_LINK_DOWN_FLAG = 1 << 1,
221 };
222 
223 struct ntb_payload_header {
224 	ntb_q_idx_t ver;
225 	uint32_t len;
226 	uint32_t flags;
227 };
228 
229 enum {
230 	/*
231 	 * The order of this enum is part of the remote protocol.  Do not
232 	 * reorder without bumping protocol version (and it's probably best
233 	 * to keep the protocol in lock-step with the Linux NTB driver.
234 	 */
235 	NTBT_VERSION = 0,
236 	NTBT_QP_LINKS,
237 	NTBT_NUM_QPS,
238 	NTBT_NUM_MWS,
239 	/*
240 	 * N.B.: transport_link_work assumes MW1 enums = MW0 + 2.
241 	 */
242 	NTBT_MW0_SZ_HIGH,
243 	NTBT_MW0_SZ_LOW,
244 	NTBT_MW1_SZ_HIGH,
245 	NTBT_MW1_SZ_LOW,
246 	NTBT_MAX_SPAD,
247 
248 	/*
249 	 * Some NTB-using hardware have a watchdog to work around NTB hangs; if
250 	 * a register or doorbell isn't written every few seconds, the link is
251 	 * torn down.  Write an otherwise unused register every few seconds to
252 	 * work around this watchdog.
253 	 */
254 	NTBT_WATCHDOG_SPAD = 15
255 };
256 
257 #define QP_TO_MW(nt, qp)	((qp) % nt->mw_count)
258 #define NTB_QP_DEF_NUM_ENTRIES	100
259 #define NTB_LINK_DOWN_TIMEOUT	10
260 
261 static int ntb_transport_probe(device_t dev);
262 static int ntb_transport_attach(device_t dev);
263 static int ntb_transport_detach(device_t dev);
264 static void ntb_transport_init_queue(struct ntb_transport_ctx *nt,
265     unsigned int qp_num);
266 static int ntb_process_tx(struct ntb_transport_qp *qp,
267     struct ntb_queue_entry *entry);
268 static void ntb_transport_rxc_db(void *arg, int pending);
269 static int ntb_process_rxc(struct ntb_transport_qp *qp);
270 static void ntb_memcpy_rx(struct ntb_transport_qp *qp,
271     struct ntb_queue_entry *entry, void *offset);
272 static inline void ntb_rx_copy_callback(struct ntb_transport_qp *qp,
273     void *data);
274 static void ntb_complete_rxc(struct ntb_transport_qp *qp);
275 static void ntb_transport_doorbell_callback(void *data, uint32_t vector);
276 static void ntb_transport_event_callback(void *data);
277 static void ntb_transport_link_work(void *arg);
278 static int ntb_set_mw(struct ntb_transport_ctx *, int num_mw, size_t size);
279 static void ntb_free_mw(struct ntb_transport_ctx *nt, int num_mw);
280 static int ntb_transport_setup_qp_mw(struct ntb_transport_ctx *nt,
281     unsigned int qp_num);
282 static void ntb_qp_link_work(void *arg);
283 static void ntb_transport_link_cleanup(struct ntb_transport_ctx *nt);
284 static void ntb_transport_link_cleanup_work(void *, int);
285 static void ntb_qp_link_down(struct ntb_transport_qp *qp);
286 static void ntb_qp_link_down_reset(struct ntb_transport_qp *qp);
287 static void ntb_qp_link_cleanup(struct ntb_transport_qp *qp);
288 static void ntb_send_link_down(struct ntb_transport_qp *qp);
289 static void ntb_list_add(struct mtx *lock, struct ntb_queue_entry *entry,
290     struct ntb_queue_list *list);
291 static struct ntb_queue_entry *ntb_list_rm(struct mtx *lock,
292     struct ntb_queue_list *list);
293 static struct ntb_queue_entry *ntb_list_mv(struct mtx *lock,
294     struct ntb_queue_list *from, struct ntb_queue_list *to);
295 static void xeon_link_watchdog_hb(void *);
296 
297 static const struct ntb_ctx_ops ntb_transport_ops = {
298 	.link_event = ntb_transport_event_callback,
299 	.db_event = ntb_transport_doorbell_callback,
300 };
301 
302 MALLOC_DEFINE(M_NTB_T, "ntb_transport", "ntb transport driver");
303 
304 static inline void
305 iowrite32(uint32_t val, void *addr)
306 {
307 
308 	bus_space_write_4(X86_BUS_SPACE_MEM, 0/* HACK */, (uintptr_t)addr,
309 	    val);
310 }
311 
312 /* Transport Init and teardown */
313 
314 static void
315 xeon_link_watchdog_hb(void *arg)
316 {
317 	struct ntb_transport_ctx *nt;
318 
319 	nt = arg;
320 	NTB_SPAD_WRITE(nt->ntb, NTBT_WATCHDOG_SPAD, 0);
321 	callout_reset(&nt->link_watchdog, 1 * hz, xeon_link_watchdog_hb, nt);
322 }
323 
324 static int
325 ntb_transport_probe(device_t dev)
326 {
327 
328 	device_set_desc(dev, "NTB Transport");
329 	return (0);
330 }
331 
332 static int
333 ntb_transport_attach(device_t dev)
334 {
335 	struct ntb_transport_ctx *nt = device_get_softc(dev);
336 	device_t ntb = device_get_parent(dev);
337 	struct ntb_transport_mw *mw;
338 	uint64_t qp_bitmap;
339 	int rc;
340 	unsigned i;
341 
342 	nt->dev = dev;
343 	nt->ntb = ntb;
344 	nt->mw_count = NTB_MW_COUNT(ntb);
345 	nt->mw_vec = malloc(nt->mw_count * sizeof(*nt->mw_vec), M_NTB_T,
346 	    M_WAITOK | M_ZERO);
347 	for (i = 0; i < nt->mw_count; i++) {
348 		mw = &nt->mw_vec[i];
349 
350 		rc = NTB_MW_GET_RANGE(ntb, i, &mw->phys_addr, &mw->vbase,
351 		    &mw->phys_size, &mw->xlat_align, &mw->xlat_align_size,
352 		    &mw->addr_limit);
353 		if (rc != 0)
354 			goto err;
355 
356 		mw->buff_size = 0;
357 		mw->xlat_size = 0;
358 		mw->virt_addr = NULL;
359 		mw->dma_addr = 0;
360 
361 		rc = NTB_MW_SET_WC(nt->ntb, i, VM_MEMATTR_WRITE_COMBINING);
362 		if (rc)
363 			ntb_printf(0, "Unable to set mw%d caching\n", i);
364 	}
365 
366 	qp_bitmap = NTB_DB_VALID_MASK(ntb);
367 	nt->qp_count = flsll(qp_bitmap);
368 	KASSERT(nt->qp_count != 0, ("bogus db bitmap"));
369 	nt->qp_count -= 1;
370 
371 	if (max_num_clients != 0 && max_num_clients < nt->qp_count)
372 		nt->qp_count = max_num_clients;
373 	else if (nt->mw_count < nt->qp_count)
374 		nt->qp_count = nt->mw_count;
375 	KASSERT(nt->qp_count <= QP_SETSIZE, ("invalid qp_count"));
376 
377 	nt->qp_vec = malloc(nt->qp_count * sizeof(*nt->qp_vec), M_NTB_T,
378 	    M_WAITOK | M_ZERO);
379 
380 	for (i = 0; i < nt->qp_count; i++) {
381 		set_bit(i, &nt->qp_bitmap);
382 		set_bit(i, &nt->qp_bitmap_free);
383 		ntb_transport_init_queue(nt, i);
384 	}
385 
386 	callout_init(&nt->link_work, 0);
387 	callout_init(&nt->link_watchdog, 0);
388 	TASK_INIT(&nt->link_cleanup, 0, ntb_transport_link_cleanup_work, nt);
389 
390 	rc = NTB_SET_CTX(ntb, nt, &ntb_transport_ops);
391 	if (rc != 0)
392 		goto err;
393 
394 	nt->link_is_up = false;
395 	NTB_LINK_ENABLE(ntb, NTB_SPEED_AUTO, NTB_WIDTH_AUTO);
396 
397 	if (enable_xeon_watchdog != 0)
398 		callout_reset(&nt->link_watchdog, 0, xeon_link_watchdog_hb, nt);
399 
400 	/* Attach children to this transport */
401 	device_add_child(dev, NULL, -1);
402 	bus_generic_attach(dev);
403 
404 	return (0);
405 
406 err:
407 	free(nt->qp_vec, M_NTB_T);
408 	free(nt->mw_vec, M_NTB_T);
409 	return (rc);
410 }
411 
412 static int
413 ntb_transport_detach(device_t dev)
414 {
415 	struct ntb_transport_ctx *nt = device_get_softc(dev);
416 	device_t ntb = nt->ntb;
417 	struct _qpset qp_bitmap_alloc;
418 	uint8_t i;
419 
420 	/* Detach & delete all children */
421 	device_delete_children(dev);
422 
423 	ntb_transport_link_cleanup(nt);
424 	taskqueue_drain(taskqueue_swi, &nt->link_cleanup);
425 	callout_drain(&nt->link_work);
426 	callout_drain(&nt->link_watchdog);
427 
428 	BIT_COPY(QP_SETSIZE, &nt->qp_bitmap, &qp_bitmap_alloc);
429 	BIT_NAND(QP_SETSIZE, &qp_bitmap_alloc, &nt->qp_bitmap_free);
430 
431 	/* Verify that all the QPs are freed */
432 	for (i = 0; i < nt->qp_count; i++)
433 		if (test_bit(i, &qp_bitmap_alloc))
434 			ntb_transport_free_queue(&nt->qp_vec[i]);
435 
436 	NTB_LINK_DISABLE(ntb);
437 	NTB_CLEAR_CTX(ntb);
438 
439 	for (i = 0; i < nt->mw_count; i++)
440 		ntb_free_mw(nt, i);
441 
442 	free(nt->qp_vec, M_NTB_T);
443 	free(nt->mw_vec, M_NTB_T);
444 	return (0);
445 }
446 
447 static void
448 ntb_transport_init_queue(struct ntb_transport_ctx *nt, unsigned int qp_num)
449 {
450 	struct ntb_transport_mw *mw;
451 	struct ntb_transport_qp *qp;
452 	vm_paddr_t mw_base;
453 	uint64_t mw_size, qp_offset;
454 	size_t tx_size;
455 	unsigned num_qps_mw, mw_num, mw_count;
456 
457 	mw_count = nt->mw_count;
458 	mw_num = QP_TO_MW(nt, qp_num);
459 	mw = &nt->mw_vec[mw_num];
460 
461 	qp = &nt->qp_vec[qp_num];
462 	qp->qp_num = qp_num;
463 	qp->transport = nt;
464 	qp->ntb = nt->ntb;
465 	qp->client_ready = false;
466 	qp->event_handler = NULL;
467 	ntb_qp_link_down_reset(qp);
468 
469 	if (mw_num < nt->qp_count % mw_count)
470 		num_qps_mw = nt->qp_count / mw_count + 1;
471 	else
472 		num_qps_mw = nt->qp_count / mw_count;
473 
474 	mw_base = mw->phys_addr;
475 	mw_size = mw->phys_size;
476 
477 	tx_size = mw_size / num_qps_mw;
478 	qp_offset = tx_size * (qp_num / mw_count);
479 
480 	qp->tx_mw = mw->vbase + qp_offset;
481 	KASSERT(qp->tx_mw != NULL, ("uh oh?"));
482 
483 	/* XXX Assumes that a vm_paddr_t is equivalent to bus_addr_t */
484 	qp->tx_mw_phys = mw_base + qp_offset;
485 	KASSERT(qp->tx_mw_phys != 0, ("uh oh?"));
486 
487 	tx_size -= sizeof(struct ntb_rx_info);
488 	qp->rx_info = (void *)(qp->tx_mw + tx_size);
489 
490 	/* Due to house-keeping, there must be at least 2 buffs */
491 	qp->tx_max_frame = qmin(transport_mtu, tx_size / 2);
492 	qp->tx_max_entry = tx_size / qp->tx_max_frame;
493 
494 	callout_init(&qp->link_work, 0);
495 	callout_init(&qp->rx_full, 1);
496 
497 	mtx_init(&qp->ntb_rx_q_lock, "ntb rx q", NULL, MTX_SPIN);
498 	mtx_init(&qp->ntb_tx_free_q_lock, "ntb tx free q", NULL, MTX_SPIN);
499 	mtx_init(&qp->tx_lock, "ntb transport tx", NULL, MTX_DEF);
500 	TASK_INIT(&qp->rxc_db_work, 0, ntb_transport_rxc_db, qp);
501 	qp->rxc_tq = taskqueue_create("ntbt_rx", M_WAITOK,
502 	    taskqueue_thread_enqueue, &qp->rxc_tq);
503 	taskqueue_start_threads(&qp->rxc_tq, 1, PI_NET, "%s rx%d",
504 	    device_get_nameunit(nt->dev), qp_num);
505 
506 	STAILQ_INIT(&qp->rx_post_q);
507 	STAILQ_INIT(&qp->rx_pend_q);
508 	STAILQ_INIT(&qp->tx_free_q);
509 }
510 
511 void
512 ntb_transport_free_queue(struct ntb_transport_qp *qp)
513 {
514 	struct ntb_queue_entry *entry;
515 
516 	if (qp == NULL)
517 		return;
518 
519 	callout_drain(&qp->link_work);
520 
521 	NTB_DB_SET_MASK(qp->ntb, 1ull << qp->qp_num);
522 	taskqueue_drain_all(qp->rxc_tq);
523 	taskqueue_free(qp->rxc_tq);
524 
525 	qp->cb_data = NULL;
526 	qp->rx_handler = NULL;
527 	qp->tx_handler = NULL;
528 	qp->event_handler = NULL;
529 
530 	while ((entry = ntb_list_rm(&qp->ntb_rx_q_lock, &qp->rx_pend_q)))
531 		free(entry, M_NTB_T);
532 
533 	while ((entry = ntb_list_rm(&qp->ntb_rx_q_lock, &qp->rx_post_q)))
534 		free(entry, M_NTB_T);
535 
536 	while ((entry = ntb_list_rm(&qp->ntb_tx_free_q_lock, &qp->tx_free_q)))
537 		free(entry, M_NTB_T);
538 
539 	set_bit(qp->qp_num, &qp->transport->qp_bitmap_free);
540 }
541 
542 /**
543  * ntb_transport_create_queue - Create a new NTB transport layer queue
544  * @rx_handler: receive callback function
545  * @tx_handler: transmit callback function
546  * @event_handler: event callback function
547  *
548  * Create a new NTB transport layer queue and provide the queue with a callback
549  * routine for both transmit and receive.  The receive callback routine will be
550  * used to pass up data when the transport has received it on the queue.   The
551  * transmit callback routine will be called when the transport has completed the
552  * transmission of the data on the queue and the data is ready to be freed.
553  *
554  * RETURNS: pointer to newly created ntb_queue, NULL on error.
555  */
556 struct ntb_transport_qp *
557 ntb_transport_create_queue(void *data, device_t dev,
558     const struct ntb_queue_handlers *handlers)
559 {
560 	struct ntb_transport_ctx *nt = device_get_softc(dev);
561 	device_t ntb = device_get_parent(dev);
562 	struct ntb_queue_entry *entry;
563 	struct ntb_transport_qp *qp;
564 	unsigned int free_queue;
565 	int i;
566 
567 	free_queue = ffs_bit(&nt->qp_bitmap_free);
568 	if (free_queue == 0)
569 		return (NULL);
570 
571 	/* decrement free_queue to make it zero based */
572 	free_queue--;
573 
574 	qp = &nt->qp_vec[free_queue];
575 	clear_bit(qp->qp_num, &nt->qp_bitmap_free);
576 	qp->cb_data = data;
577 	qp->rx_handler = handlers->rx_handler;
578 	qp->tx_handler = handlers->tx_handler;
579 	qp->event_handler = handlers->event_handler;
580 
581 	for (i = 0; i < NTB_QP_DEF_NUM_ENTRIES; i++) {
582 		entry = malloc(sizeof(*entry), M_NTB_T, M_WAITOK | M_ZERO);
583 		entry->cb_data = data;
584 		entry->buf = NULL;
585 		entry->len = transport_mtu;
586 		entry->qp = qp;
587 		ntb_list_add(&qp->ntb_rx_q_lock, entry, &qp->rx_pend_q);
588 	}
589 
590 	for (i = 0; i < NTB_QP_DEF_NUM_ENTRIES; i++) {
591 		entry = malloc(sizeof(*entry), M_NTB_T, M_WAITOK | M_ZERO);
592 		entry->qp = qp;
593 		ntb_list_add(&qp->ntb_tx_free_q_lock, entry, &qp->tx_free_q);
594 	}
595 
596 	NTB_DB_CLEAR(ntb, 1ull << qp->qp_num);
597 	return (qp);
598 }
599 
600 /**
601  * ntb_transport_link_up - Notify NTB transport of client readiness to use queue
602  * @qp: NTB transport layer queue to be enabled
603  *
604  * Notify NTB transport layer of client readiness to use queue
605  */
606 void
607 ntb_transport_link_up(struct ntb_transport_qp *qp)
608 {
609 	struct ntb_transport_ctx *nt = qp->transport;
610 
611 	qp->client_ready = true;
612 
613 	ntb_printf(2, "qp %d client ready\n", qp->qp_num);
614 
615 	if (nt->link_is_up)
616 		callout_reset(&qp->link_work, 0, ntb_qp_link_work, qp);
617 }
618 
619 
620 
621 /* Transport Tx */
622 
623 /**
624  * ntb_transport_tx_enqueue - Enqueue a new NTB queue entry
625  * @qp: NTB transport layer queue the entry is to be enqueued on
626  * @cb: per buffer pointer for callback function to use
627  * @data: pointer to data buffer that will be sent
628  * @len: length of the data buffer
629  *
630  * Enqueue a new transmit buffer onto the transport queue from which a NTB
631  * payload will be transmitted.  This assumes that a lock is being held to
632  * serialize access to the qp.
633  *
634  * RETURNS: An appropriate ERRNO error value on error, or zero for success.
635  */
636 int
637 ntb_transport_tx_enqueue(struct ntb_transport_qp *qp, void *cb, void *data,
638     unsigned int len)
639 {
640 	struct ntb_queue_entry *entry;
641 	int rc;
642 
643 	if (qp == NULL || !qp->link_is_up || len == 0) {
644 		CTR0(KTR_NTB, "TX: link not up");
645 		return (EINVAL);
646 	}
647 
648 	entry = ntb_list_rm(&qp->ntb_tx_free_q_lock, &qp->tx_free_q);
649 	if (entry == NULL) {
650 		CTR0(KTR_NTB, "TX: could not get entry from tx_free_q");
651 		qp->tx_err_no_buf++;
652 		return (EBUSY);
653 	}
654 	CTR1(KTR_NTB, "TX: got entry %p from tx_free_q", entry);
655 
656 	entry->cb_data = cb;
657 	entry->buf = data;
658 	entry->len = len;
659 	entry->flags = 0;
660 
661 	mtx_lock(&qp->tx_lock);
662 	rc = ntb_process_tx(qp, entry);
663 	mtx_unlock(&qp->tx_lock);
664 	if (rc != 0) {
665 		ntb_list_add(&qp->ntb_tx_free_q_lock, entry, &qp->tx_free_q);
666 		CTR1(KTR_NTB,
667 		    "TX: process_tx failed. Returning entry %p to tx_free_q",
668 		    entry);
669 	}
670 	return (rc);
671 }
672 
673 static void
674 ntb_tx_copy_callback(void *data)
675 {
676 	struct ntb_queue_entry *entry = data;
677 	struct ntb_transport_qp *qp = entry->qp;
678 	struct ntb_payload_header *hdr = entry->x_hdr;
679 
680 	iowrite32(entry->flags | NTBT_DESC_DONE_FLAG, &hdr->flags);
681 	CTR1(KTR_NTB, "TX: hdr %p set DESC_DONE", hdr);
682 
683 	NTB_PEER_DB_SET(qp->ntb, 1ull << qp->qp_num);
684 
685 	/*
686 	 * The entry length can only be zero if the packet is intended to be a
687 	 * "link down" or similar.  Since no payload is being sent in these
688 	 * cases, there is nothing to add to the completion queue.
689 	 */
690 	if (entry->len > 0) {
691 		qp->tx_bytes += entry->len;
692 
693 		if (qp->tx_handler)
694 			qp->tx_handler(qp, qp->cb_data, entry->buf,
695 			    entry->len);
696 		else
697 			m_freem(entry->buf);
698 		entry->buf = NULL;
699 	}
700 
701 	CTR3(KTR_NTB,
702 	    "TX: entry %p sent. hdr->ver = %u, hdr->flags = 0x%x, Returning "
703 	    "to tx_free_q", entry, hdr->ver, hdr->flags);
704 	ntb_list_add(&qp->ntb_tx_free_q_lock, entry, &qp->tx_free_q);
705 }
706 
707 static void
708 ntb_memcpy_tx(struct ntb_queue_entry *entry, void *offset)
709 {
710 
711 	CTR2(KTR_NTB, "TX: copying %d bytes to offset %p", entry->len, offset);
712 	if (entry->buf != NULL) {
713 		m_copydata((struct mbuf *)entry->buf, 0, entry->len, offset);
714 
715 		/*
716 		 * Ensure that the data is fully copied before setting the
717 		 * flags
718 		 */
719 		wmb();
720 	}
721 
722 	ntb_tx_copy_callback(entry);
723 }
724 
725 static void
726 ntb_async_tx(struct ntb_transport_qp *qp, struct ntb_queue_entry *entry)
727 {
728 	struct ntb_payload_header *hdr;
729 	void *offset;
730 
731 	offset = qp->tx_mw + qp->tx_max_frame * qp->tx_index;
732 	hdr = (struct ntb_payload_header *)((char *)offset + qp->tx_max_frame -
733 	    sizeof(struct ntb_payload_header));
734 	entry->x_hdr = hdr;
735 
736 	iowrite32(entry->len, &hdr->len);
737 	iowrite32(qp->tx_pkts, &hdr->ver);
738 
739 	ntb_memcpy_tx(entry, offset);
740 }
741 
742 static int
743 ntb_process_tx(struct ntb_transport_qp *qp, struct ntb_queue_entry *entry)
744 {
745 
746 	CTR3(KTR_NTB,
747 	    "TX: process_tx: tx_pkts=%lu, tx_index=%u, remote entry=%u",
748 	    qp->tx_pkts, qp->tx_index, qp->remote_rx_info->entry);
749 	if (qp->tx_index == qp->remote_rx_info->entry) {
750 		CTR0(KTR_NTB, "TX: ring full");
751 		qp->tx_ring_full++;
752 		return (EAGAIN);
753 	}
754 
755 	if (entry->len > qp->tx_max_frame - sizeof(struct ntb_payload_header)) {
756 		if (qp->tx_handler != NULL)
757 			qp->tx_handler(qp, qp->cb_data, entry->buf,
758 			    EIO);
759 		else
760 			m_freem(entry->buf);
761 
762 		entry->buf = NULL;
763 		ntb_list_add(&qp->ntb_tx_free_q_lock, entry, &qp->tx_free_q);
764 		CTR1(KTR_NTB,
765 		    "TX: frame too big. returning entry %p to tx_free_q",
766 		    entry);
767 		return (0);
768 	}
769 	CTR2(KTR_NTB, "TX: copying entry %p to index %u", entry, qp->tx_index);
770 	ntb_async_tx(qp, entry);
771 
772 	qp->tx_index++;
773 	qp->tx_index %= qp->tx_max_entry;
774 
775 	qp->tx_pkts++;
776 
777 	return (0);
778 }
779 
780 /* Transport Rx */
781 static void
782 ntb_transport_rxc_db(void *arg, int pending __unused)
783 {
784 	struct ntb_transport_qp *qp = arg;
785 	int rc;
786 
787 	CTR0(KTR_NTB, "RX: transport_rx");
788 again:
789 	while ((rc = ntb_process_rxc(qp)) == 0)
790 		;
791 	CTR1(KTR_NTB, "RX: process_rxc returned %d", rc);
792 
793 	if ((NTB_DB_READ(qp->ntb) & (1ull << qp->qp_num)) != 0) {
794 		/* If db is set, clear it and check queue once more. */
795 		NTB_DB_CLEAR(qp->ntb, 1ull << qp->qp_num);
796 		goto again;
797 	}
798 }
799 
800 static int
801 ntb_process_rxc(struct ntb_transport_qp *qp)
802 {
803 	struct ntb_payload_header *hdr;
804 	struct ntb_queue_entry *entry;
805 	caddr_t offset;
806 
807 	offset = qp->rx_buff + qp->rx_max_frame * qp->rx_index;
808 	hdr = (void *)(offset + qp->rx_max_frame -
809 	    sizeof(struct ntb_payload_header));
810 
811 	CTR1(KTR_NTB, "RX: process_rxc rx_index = %u", qp->rx_index);
812 	if ((hdr->flags & NTBT_DESC_DONE_FLAG) == 0) {
813 		CTR0(KTR_NTB, "RX: hdr not done");
814 		qp->rx_ring_empty++;
815 		return (EAGAIN);
816 	}
817 
818 	if ((hdr->flags & NTBT_LINK_DOWN_FLAG) != 0) {
819 		CTR0(KTR_NTB, "RX: link down");
820 		ntb_qp_link_down(qp);
821 		hdr->flags = 0;
822 		return (EAGAIN);
823 	}
824 
825 	if (hdr->ver != (uint32_t)qp->rx_pkts) {
826 		CTR2(KTR_NTB,"RX: ver != rx_pkts (%x != %lx). "
827 		    "Returning entry to rx_pend_q", hdr->ver, qp->rx_pkts);
828 		qp->rx_err_ver++;
829 		return (EIO);
830 	}
831 
832 	entry = ntb_list_mv(&qp->ntb_rx_q_lock, &qp->rx_pend_q, &qp->rx_post_q);
833 	if (entry == NULL) {
834 		qp->rx_err_no_buf++;
835 		CTR0(KTR_NTB, "RX: No entries in rx_pend_q");
836 		return (EAGAIN);
837 	}
838 	callout_stop(&qp->rx_full);
839 	CTR1(KTR_NTB, "RX: rx entry %p from rx_pend_q", entry);
840 
841 	entry->x_hdr = hdr;
842 	entry->index = qp->rx_index;
843 
844 	if (hdr->len > entry->len) {
845 		CTR2(KTR_NTB, "RX: len too long. Wanted %ju got %ju",
846 		    (uintmax_t)hdr->len, (uintmax_t)entry->len);
847 		qp->rx_err_oflow++;
848 
849 		entry->len = -EIO;
850 		entry->flags |= NTBT_DESC_DONE_FLAG;
851 
852 		ntb_complete_rxc(qp);
853 	} else {
854 		qp->rx_bytes += hdr->len;
855 		qp->rx_pkts++;
856 
857 		CTR1(KTR_NTB, "RX: received %ld rx_pkts", qp->rx_pkts);
858 
859 		entry->len = hdr->len;
860 
861 		ntb_memcpy_rx(qp, entry, offset);
862 	}
863 
864 	qp->rx_index++;
865 	qp->rx_index %= qp->rx_max_entry;
866 	return (0);
867 }
868 
869 static void
870 ntb_memcpy_rx(struct ntb_transport_qp *qp, struct ntb_queue_entry *entry,
871     void *offset)
872 {
873 	struct ifnet *ifp = entry->cb_data;
874 	unsigned int len = entry->len;
875 
876 	CTR2(KTR_NTB, "RX: copying %d bytes from offset %p", len, offset);
877 
878 	entry->buf = (void *)m_devget(offset, len, 0, ifp, NULL);
879 	if (entry->buf == NULL)
880 		entry->len = -ENOMEM;
881 
882 	/* Ensure that the data is globally visible before clearing the flag */
883 	wmb();
884 
885 	CTR2(KTR_NTB, "RX: copied entry %p to mbuf %p.", entry, entry->buf);
886 	ntb_rx_copy_callback(qp, entry);
887 }
888 
889 static inline void
890 ntb_rx_copy_callback(struct ntb_transport_qp *qp, void *data)
891 {
892 	struct ntb_queue_entry *entry;
893 
894 	entry = data;
895 	entry->flags |= NTBT_DESC_DONE_FLAG;
896 	ntb_complete_rxc(qp);
897 }
898 
899 static void
900 ntb_complete_rxc(struct ntb_transport_qp *qp)
901 {
902 	struct ntb_queue_entry *entry;
903 	struct mbuf *m;
904 	unsigned len;
905 
906 	CTR0(KTR_NTB, "RX: rx_completion_task");
907 
908 	mtx_lock_spin(&qp->ntb_rx_q_lock);
909 
910 	while (!STAILQ_EMPTY(&qp->rx_post_q)) {
911 		entry = STAILQ_FIRST(&qp->rx_post_q);
912 		if ((entry->flags & NTBT_DESC_DONE_FLAG) == 0)
913 			break;
914 
915 		entry->x_hdr->flags = 0;
916 		iowrite32(entry->index, &qp->rx_info->entry);
917 
918 		STAILQ_REMOVE_HEAD(&qp->rx_post_q, entry);
919 
920 		len = entry->len;
921 		m = entry->buf;
922 
923 		/*
924 		 * Re-initialize queue_entry for reuse; rx_handler takes
925 		 * ownership of the mbuf.
926 		 */
927 		entry->buf = NULL;
928 		entry->len = transport_mtu;
929 		entry->cb_data = qp->cb_data;
930 
931 		STAILQ_INSERT_TAIL(&qp->rx_pend_q, entry, entry);
932 
933 		mtx_unlock_spin(&qp->ntb_rx_q_lock);
934 
935 		CTR2(KTR_NTB, "RX: completing entry %p, mbuf %p", entry, m);
936 		if (qp->rx_handler != NULL && qp->client_ready)
937 			qp->rx_handler(qp, qp->cb_data, m, len);
938 		else
939 			m_freem(m);
940 
941 		mtx_lock_spin(&qp->ntb_rx_q_lock);
942 	}
943 
944 	mtx_unlock_spin(&qp->ntb_rx_q_lock);
945 }
946 
947 static void
948 ntb_transport_doorbell_callback(void *data, uint32_t vector)
949 {
950 	struct ntb_transport_ctx *nt = data;
951 	struct ntb_transport_qp *qp;
952 	struct _qpset db_bits;
953 	uint64_t vec_mask;
954 	unsigned qp_num;
955 
956 	BIT_COPY(QP_SETSIZE, &nt->qp_bitmap, &db_bits);
957 	BIT_NAND(QP_SETSIZE, &db_bits, &nt->qp_bitmap_free);
958 
959 	vec_mask = NTB_DB_VECTOR_MASK(nt->ntb, vector);
960 	if ((vec_mask & (vec_mask - 1)) != 0)
961 		vec_mask &= NTB_DB_READ(nt->ntb);
962 	while (vec_mask != 0) {
963 		qp_num = ffsll(vec_mask) - 1;
964 
965 		if (test_bit(qp_num, &db_bits)) {
966 			qp = &nt->qp_vec[qp_num];
967 			if (qp->link_is_up)
968 				taskqueue_enqueue(qp->rxc_tq, &qp->rxc_db_work);
969 		}
970 
971 		vec_mask &= ~(1ull << qp_num);
972 	}
973 }
974 
975 /* Link Event handler */
976 static void
977 ntb_transport_event_callback(void *data)
978 {
979 	struct ntb_transport_ctx *nt = data;
980 
981 	if (NTB_LINK_IS_UP(nt->ntb, NULL, NULL)) {
982 		ntb_printf(1, "HW link up\n");
983 		callout_reset(&nt->link_work, 0, ntb_transport_link_work, nt);
984 	} else {
985 		ntb_printf(1, "HW link down\n");
986 		taskqueue_enqueue(taskqueue_swi, &nt->link_cleanup);
987 	}
988 }
989 
990 /* Link bring up */
991 static void
992 ntb_transport_link_work(void *arg)
993 {
994 	struct ntb_transport_ctx *nt = arg;
995 	device_t ntb = nt->ntb;
996 	struct ntb_transport_qp *qp;
997 	uint64_t val64, size;
998 	uint32_t val;
999 	unsigned i;
1000 	int rc;
1001 
1002 	/* send the local info, in the opposite order of the way we read it */
1003 	for (i = 0; i < nt->mw_count; i++) {
1004 		size = nt->mw_vec[i].phys_size;
1005 
1006 		if (max_mw_size != 0 && size > max_mw_size)
1007 			size = max_mw_size;
1008 
1009 		NTB_PEER_SPAD_WRITE(ntb, NTBT_MW0_SZ_HIGH + (i * 2),
1010 		    size >> 32);
1011 		NTB_PEER_SPAD_WRITE(ntb, NTBT_MW0_SZ_LOW + (i * 2), size);
1012 	}
1013 
1014 	NTB_PEER_SPAD_WRITE(ntb, NTBT_NUM_MWS, nt->mw_count);
1015 
1016 	NTB_PEER_SPAD_WRITE(ntb, NTBT_NUM_QPS, nt->qp_count);
1017 
1018 	NTB_PEER_SPAD_WRITE(ntb, NTBT_VERSION, NTB_TRANSPORT_VERSION);
1019 
1020 	/* Query the remote side for its info */
1021 	val = 0;
1022 	NTB_SPAD_READ(ntb, NTBT_VERSION, &val);
1023 	if (val != NTB_TRANSPORT_VERSION)
1024 		goto out;
1025 
1026 	NTB_SPAD_READ(ntb, NTBT_NUM_QPS, &val);
1027 	if (val != nt->qp_count)
1028 		goto out;
1029 
1030 	NTB_SPAD_READ(ntb, NTBT_NUM_MWS, &val);
1031 	if (val != nt->mw_count)
1032 		goto out;
1033 
1034 	for (i = 0; i < nt->mw_count; i++) {
1035 		NTB_SPAD_READ(ntb, NTBT_MW0_SZ_HIGH + (i * 2), &val);
1036 		val64 = (uint64_t)val << 32;
1037 
1038 		NTB_SPAD_READ(ntb, NTBT_MW0_SZ_LOW + (i * 2), &val);
1039 		val64 |= val;
1040 
1041 		rc = ntb_set_mw(nt, i, val64);
1042 		if (rc != 0)
1043 			goto free_mws;
1044 	}
1045 
1046 	nt->link_is_up = true;
1047 	ntb_printf(1, "transport link up\n");
1048 
1049 	for (i = 0; i < nt->qp_count; i++) {
1050 		qp = &nt->qp_vec[i];
1051 
1052 		ntb_transport_setup_qp_mw(nt, i);
1053 
1054 		if (qp->client_ready)
1055 			callout_reset(&qp->link_work, 0, ntb_qp_link_work, qp);
1056 	}
1057 
1058 	return;
1059 
1060 free_mws:
1061 	for (i = 0; i < nt->mw_count; i++)
1062 		ntb_free_mw(nt, i);
1063 out:
1064 	if (NTB_LINK_IS_UP(ntb, NULL, NULL))
1065 		callout_reset(&nt->link_work,
1066 		    NTB_LINK_DOWN_TIMEOUT * hz / 1000, ntb_transport_link_work, nt);
1067 }
1068 
1069 static int
1070 ntb_set_mw(struct ntb_transport_ctx *nt, int num_mw, size_t size)
1071 {
1072 	struct ntb_transport_mw *mw = &nt->mw_vec[num_mw];
1073 	size_t xlat_size, buff_size;
1074 	int rc;
1075 
1076 	if (size == 0)
1077 		return (EINVAL);
1078 
1079 	xlat_size = roundup(size, mw->xlat_align_size);
1080 	buff_size = xlat_size;
1081 
1082 	/* No need to re-setup */
1083 	if (mw->xlat_size == xlat_size)
1084 		return (0);
1085 
1086 	if (mw->buff_size != 0)
1087 		ntb_free_mw(nt, num_mw);
1088 
1089 	/* Alloc memory for receiving data.  Must be aligned */
1090 	mw->xlat_size = xlat_size;
1091 	mw->buff_size = buff_size;
1092 
1093 	mw->virt_addr = contigmalloc(mw->buff_size, M_NTB_T, M_ZERO, 0,
1094 	    mw->addr_limit, mw->xlat_align, 0);
1095 	if (mw->virt_addr == NULL) {
1096 		ntb_printf(0, "Unable to allocate MW buffer of size %zu/%zu\n",
1097 		    mw->buff_size, mw->xlat_size);
1098 		mw->xlat_size = 0;
1099 		mw->buff_size = 0;
1100 		return (ENOMEM);
1101 	}
1102 	/* TODO: replace with bus_space_* functions */
1103 	mw->dma_addr = vtophys(mw->virt_addr);
1104 
1105 	/*
1106 	 * Ensure that the allocation from contigmalloc is aligned as
1107 	 * requested.  XXX: This may not be needed -- brought in for parity
1108 	 * with the Linux driver.
1109 	 */
1110 	if (mw->dma_addr % mw->xlat_align != 0) {
1111 		ntb_printf(0,
1112 		    "DMA memory 0x%jx not aligned to BAR size 0x%zx\n",
1113 		    (uintmax_t)mw->dma_addr, size);
1114 		ntb_free_mw(nt, num_mw);
1115 		return (ENOMEM);
1116 	}
1117 
1118 	/* Notify HW the memory location of the receive buffer */
1119 	rc = NTB_MW_SET_TRANS(nt->ntb, num_mw, mw->dma_addr, mw->xlat_size);
1120 	if (rc) {
1121 		ntb_printf(0, "Unable to set mw%d translation\n", num_mw);
1122 		ntb_free_mw(nt, num_mw);
1123 		return (rc);
1124 	}
1125 
1126 	return (0);
1127 }
1128 
1129 static void
1130 ntb_free_mw(struct ntb_transport_ctx *nt, int num_mw)
1131 {
1132 	struct ntb_transport_mw *mw = &nt->mw_vec[num_mw];
1133 
1134 	if (mw->virt_addr == NULL)
1135 		return;
1136 
1137 	NTB_MW_CLEAR_TRANS(nt->ntb, num_mw);
1138 	contigfree(mw->virt_addr, mw->xlat_size, M_NTB_T);
1139 	mw->xlat_size = 0;
1140 	mw->buff_size = 0;
1141 	mw->virt_addr = NULL;
1142 }
1143 
1144 static int
1145 ntb_transport_setup_qp_mw(struct ntb_transport_ctx *nt, unsigned int qp_num)
1146 {
1147 	struct ntb_transport_qp *qp = &nt->qp_vec[qp_num];
1148 	struct ntb_transport_mw *mw;
1149 	void *offset;
1150 	ntb_q_idx_t i;
1151 	size_t rx_size;
1152 	unsigned num_qps_mw, mw_num, mw_count;
1153 
1154 	mw_count = nt->mw_count;
1155 	mw_num = QP_TO_MW(nt, qp_num);
1156 	mw = &nt->mw_vec[mw_num];
1157 
1158 	if (mw->virt_addr == NULL)
1159 		return (ENOMEM);
1160 
1161 	if (mw_num < nt->qp_count % mw_count)
1162 		num_qps_mw = nt->qp_count / mw_count + 1;
1163 	else
1164 		num_qps_mw = nt->qp_count / mw_count;
1165 
1166 	rx_size = mw->xlat_size / num_qps_mw;
1167 	qp->rx_buff = mw->virt_addr + rx_size * (qp_num / mw_count);
1168 	rx_size -= sizeof(struct ntb_rx_info);
1169 
1170 	qp->remote_rx_info = (void*)(qp->rx_buff + rx_size);
1171 
1172 	/* Due to house-keeping, there must be at least 2 buffs */
1173 	qp->rx_max_frame = qmin(transport_mtu, rx_size / 2);
1174 	qp->rx_max_entry = rx_size / qp->rx_max_frame;
1175 	qp->rx_index = 0;
1176 
1177 	qp->remote_rx_info->entry = qp->rx_max_entry - 1;
1178 
1179 	/* Set up the hdr offsets with 0s */
1180 	for (i = 0; i < qp->rx_max_entry; i++) {
1181 		offset = (void *)(qp->rx_buff + qp->rx_max_frame * (i + 1) -
1182 		    sizeof(struct ntb_payload_header));
1183 		memset(offset, 0, sizeof(struct ntb_payload_header));
1184 	}
1185 
1186 	qp->rx_pkts = 0;
1187 	qp->tx_pkts = 0;
1188 	qp->tx_index = 0;
1189 
1190 	return (0);
1191 }
1192 
1193 static void
1194 ntb_qp_link_work(void *arg)
1195 {
1196 	struct ntb_transport_qp *qp = arg;
1197 	device_t ntb = qp->ntb;
1198 	struct ntb_transport_ctx *nt = qp->transport;
1199 	uint32_t val, dummy;
1200 
1201 	NTB_SPAD_READ(ntb, NTBT_QP_LINKS, &val);
1202 
1203 	NTB_PEER_SPAD_WRITE(ntb, NTBT_QP_LINKS, val | (1ull << qp->qp_num));
1204 
1205 	/* query remote spad for qp ready bits */
1206 	NTB_PEER_SPAD_READ(ntb, NTBT_QP_LINKS, &dummy);
1207 
1208 	/* See if the remote side is up */
1209 	if ((val & (1ull << qp->qp_num)) != 0) {
1210 		ntb_printf(2, "qp %d link up\n", qp->qp_num);
1211 		qp->link_is_up = true;
1212 
1213 		if (qp->event_handler != NULL)
1214 			qp->event_handler(qp->cb_data, NTB_LINK_UP);
1215 
1216 		NTB_DB_CLEAR_MASK(ntb, 1ull << qp->qp_num);
1217 	} else if (nt->link_is_up)
1218 		callout_reset(&qp->link_work,
1219 		    NTB_LINK_DOWN_TIMEOUT * hz / 1000, ntb_qp_link_work, qp);
1220 }
1221 
1222 /* Link down event*/
1223 static void
1224 ntb_transport_link_cleanup(struct ntb_transport_ctx *nt)
1225 {
1226 	struct ntb_transport_qp *qp;
1227 	struct _qpset qp_bitmap_alloc;
1228 	unsigned i;
1229 
1230 	BIT_COPY(QP_SETSIZE, &nt->qp_bitmap, &qp_bitmap_alloc);
1231 	BIT_NAND(QP_SETSIZE, &qp_bitmap_alloc, &nt->qp_bitmap_free);
1232 
1233 	/* Pass along the info to any clients */
1234 	for (i = 0; i < nt->qp_count; i++)
1235 		if (test_bit(i, &qp_bitmap_alloc)) {
1236 			qp = &nt->qp_vec[i];
1237 			ntb_qp_link_cleanup(qp);
1238 			callout_drain(&qp->link_work);
1239 		}
1240 
1241 	if (!nt->link_is_up)
1242 		callout_drain(&nt->link_work);
1243 
1244 	/*
1245 	 * The scratchpad registers keep the values if the remote side
1246 	 * goes down, blast them now to give them a sane value the next
1247 	 * time they are accessed
1248 	 */
1249 	for (i = 0; i < NTBT_MAX_SPAD; i++)
1250 		NTB_SPAD_WRITE(nt->ntb, i, 0);
1251 }
1252 
1253 static void
1254 ntb_transport_link_cleanup_work(void *arg, int pending __unused)
1255 {
1256 
1257 	ntb_transport_link_cleanup(arg);
1258 }
1259 
1260 static void
1261 ntb_qp_link_down(struct ntb_transport_qp *qp)
1262 {
1263 
1264 	ntb_qp_link_cleanup(qp);
1265 }
1266 
1267 static void
1268 ntb_qp_link_down_reset(struct ntb_transport_qp *qp)
1269 {
1270 
1271 	qp->link_is_up = false;
1272 	NTB_DB_SET_MASK(qp->ntb, 1ull << qp->qp_num);
1273 
1274 	qp->tx_index = qp->rx_index = 0;
1275 	qp->tx_bytes = qp->rx_bytes = 0;
1276 	qp->tx_pkts = qp->rx_pkts = 0;
1277 
1278 	qp->rx_ring_empty = 0;
1279 	qp->tx_ring_full = 0;
1280 
1281 	qp->rx_err_no_buf = qp->tx_err_no_buf = 0;
1282 	qp->rx_err_oflow = qp->rx_err_ver = 0;
1283 }
1284 
1285 static void
1286 ntb_qp_link_cleanup(struct ntb_transport_qp *qp)
1287 {
1288 
1289 	callout_drain(&qp->link_work);
1290 	ntb_qp_link_down_reset(qp);
1291 
1292 	if (qp->event_handler != NULL)
1293 		qp->event_handler(qp->cb_data, NTB_LINK_DOWN);
1294 }
1295 
1296 /* Link commanded down */
1297 /**
1298  * ntb_transport_link_down - Notify NTB transport to no longer enqueue data
1299  * @qp: NTB transport layer queue to be disabled
1300  *
1301  * Notify NTB transport layer of client's desire to no longer receive data on
1302  * transport queue specified.  It is the client's responsibility to ensure all
1303  * entries on queue are purged or otherwise handled appropriately.
1304  */
1305 void
1306 ntb_transport_link_down(struct ntb_transport_qp *qp)
1307 {
1308 	uint32_t val;
1309 
1310 	if (qp == NULL)
1311 		return;
1312 
1313 	qp->client_ready = false;
1314 
1315 	NTB_SPAD_READ(qp->ntb, NTBT_QP_LINKS, &val);
1316 
1317 	NTB_PEER_SPAD_WRITE(qp->ntb, NTBT_QP_LINKS,
1318 	   val & ~(1 << qp->qp_num));
1319 
1320 	if (qp->link_is_up)
1321 		ntb_send_link_down(qp);
1322 	else
1323 		callout_drain(&qp->link_work);
1324 }
1325 
1326 /**
1327  * ntb_transport_link_query - Query transport link state
1328  * @qp: NTB transport layer queue to be queried
1329  *
1330  * Query connectivity to the remote system of the NTB transport queue
1331  *
1332  * RETURNS: true for link up or false for link down
1333  */
1334 bool
1335 ntb_transport_link_query(struct ntb_transport_qp *qp)
1336 {
1337 	if (qp == NULL)
1338 		return (false);
1339 
1340 	return (qp->link_is_up);
1341 }
1342 
1343 static void
1344 ntb_send_link_down(struct ntb_transport_qp *qp)
1345 {
1346 	struct ntb_queue_entry *entry;
1347 	int i, rc;
1348 
1349 	if (!qp->link_is_up)
1350 		return;
1351 
1352 	for (i = 0; i < NTB_LINK_DOWN_TIMEOUT; i++) {
1353 		entry = ntb_list_rm(&qp->ntb_tx_free_q_lock, &qp->tx_free_q);
1354 		if (entry != NULL)
1355 			break;
1356 		pause("NTB Wait for link down", hz / 10);
1357 	}
1358 
1359 	if (entry == NULL)
1360 		return;
1361 
1362 	entry->cb_data = NULL;
1363 	entry->buf = NULL;
1364 	entry->len = 0;
1365 	entry->flags = NTBT_LINK_DOWN_FLAG;
1366 
1367 	mtx_lock(&qp->tx_lock);
1368 	rc = ntb_process_tx(qp, entry);
1369 	mtx_unlock(&qp->tx_lock);
1370 	if (rc != 0)
1371 		printf("ntb: Failed to send link down\n");
1372 
1373 	ntb_qp_link_down_reset(qp);
1374 }
1375 
1376 
1377 /* List Management */
1378 
1379 static void
1380 ntb_list_add(struct mtx *lock, struct ntb_queue_entry *entry,
1381     struct ntb_queue_list *list)
1382 {
1383 
1384 	mtx_lock_spin(lock);
1385 	STAILQ_INSERT_TAIL(list, entry, entry);
1386 	mtx_unlock_spin(lock);
1387 }
1388 
1389 static struct ntb_queue_entry *
1390 ntb_list_rm(struct mtx *lock, struct ntb_queue_list *list)
1391 {
1392 	struct ntb_queue_entry *entry;
1393 
1394 	mtx_lock_spin(lock);
1395 	if (STAILQ_EMPTY(list)) {
1396 		entry = NULL;
1397 		goto out;
1398 	}
1399 	entry = STAILQ_FIRST(list);
1400 	STAILQ_REMOVE_HEAD(list, entry);
1401 out:
1402 	mtx_unlock_spin(lock);
1403 
1404 	return (entry);
1405 }
1406 
1407 static struct ntb_queue_entry *
1408 ntb_list_mv(struct mtx *lock, struct ntb_queue_list *from,
1409     struct ntb_queue_list *to)
1410 {
1411 	struct ntb_queue_entry *entry;
1412 
1413 	mtx_lock_spin(lock);
1414 	if (STAILQ_EMPTY(from)) {
1415 		entry = NULL;
1416 		goto out;
1417 	}
1418 	entry = STAILQ_FIRST(from);
1419 	STAILQ_REMOVE_HEAD(from, entry);
1420 	STAILQ_INSERT_TAIL(to, entry, entry);
1421 
1422 out:
1423 	mtx_unlock_spin(lock);
1424 	return (entry);
1425 }
1426 
1427 /**
1428  * ntb_transport_qp_num - Query the qp number
1429  * @qp: NTB transport layer queue to be queried
1430  *
1431  * Query qp number of the NTB transport queue
1432  *
1433  * RETURNS: a zero based number specifying the qp number
1434  */
1435 unsigned char ntb_transport_qp_num(struct ntb_transport_qp *qp)
1436 {
1437 	if (qp == NULL)
1438 		return 0;
1439 
1440 	return (qp->qp_num);
1441 }
1442 
1443 /**
1444  * ntb_transport_max_size - Query the max payload size of a qp
1445  * @qp: NTB transport layer queue to be queried
1446  *
1447  * Query the maximum payload size permissible on the given qp
1448  *
1449  * RETURNS: the max payload size of a qp
1450  */
1451 unsigned int
1452 ntb_transport_max_size(struct ntb_transport_qp *qp)
1453 {
1454 
1455 	if (qp == NULL)
1456 		return (0);
1457 
1458 	return (qp->tx_max_frame - sizeof(struct ntb_payload_header));
1459 }
1460 
1461 unsigned int
1462 ntb_transport_tx_free_entry(struct ntb_transport_qp *qp)
1463 {
1464 	unsigned int head = qp->tx_index;
1465 	unsigned int tail = qp->remote_rx_info->entry;
1466 
1467 	return (tail >= head ? tail - head : qp->tx_max_entry + tail - head);
1468 }
1469 
1470 static device_method_t ntb_transport_methods[] = {
1471 	/* Device interface */
1472 	DEVMETHOD(device_probe,     ntb_transport_probe),
1473 	DEVMETHOD(device_attach,    ntb_transport_attach),
1474 	DEVMETHOD(device_detach,    ntb_transport_detach),
1475 	DEVMETHOD_END
1476 };
1477 
1478 devclass_t ntb_transport_devclass;
1479 static DEFINE_CLASS_0(ntb_transport, ntb_transport_driver,
1480     ntb_transport_methods, sizeof(struct ntb_transport_ctx));
1481 DRIVER_MODULE(ntb_transport, ntb_hw, ntb_transport_driver,
1482     ntb_transport_devclass, NULL, NULL);
1483 MODULE_DEPEND(ntb_transport, ntb, 1, 1, 1);
1484 MODULE_VERSION(ntb_transport, 1);
1485