xref: /freebsd/sys/dev/ntb/if_ntb/if_ntb.c (revision 595e514d0df2bac5b813d35f83e32875dbf16a83)
1 /*-
2  * Copyright (C) 2013 Intel Corporation
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  *
14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24  * SUCH DAMAGE.
25  */
26 
27 #include <sys/cdefs.h>
28 __FBSDID("$FreeBSD$");
29 
30 #include <sys/param.h>
31 #include <sys/kernel.h>
32 #include <sys/systm.h>
33 #include <sys/bus.h>
34 #include <sys/ktr.h>
35 #include <sys/lock.h>
36 #include <sys/malloc.h>
37 #include <sys/module.h>
38 #include <sys/mutex.h>
39 #include <sys/queue.h>
40 #include <sys/socket.h>
41 #include <sys/sockio.h>
42 #include <sys/taskqueue.h>
43 #include <net/if.h>
44 #include <net/if_media.h>
45 #include <net/if_types.h>
46 #include <net/if_var.h>
47 #include <net/bpf.h>
48 #include <net/ethernet.h>
49 #include <vm/vm.h>
50 #include <vm/pmap.h>
51 #include <machine/bus.h>
52 #include <machine/cpufunc.h>
53 #include <machine/pmap.h>
54 
55 #include "../ntb_hw/ntb_hw.h"
56 
57 /*
58  * The Non-Transparent Bridge (NTB) is a device on some Intel processors that
59  * allows you to connect two systems using a PCI-e link.
60  *
61  * This module contains a protocol for sending and receiving messages, and
62  * exposes that protocol through a simulated ethernet device called ntb.
63  *
64  * NOTE: Much of the code in this module is shared with Linux. Any patches may
65  * be picked up and redistributed in Linux with a dual GPL/BSD license.
66  */
67 
68 /* TODO: These functions should really be part of the kernel */
69 #define test_bit(pos, bitmap_addr)  (*(bitmap_addr) & 1UL << (pos))
70 #define set_bit(pos, bitmap_addr)   *(bitmap_addr) |= 1UL << (pos)
71 #define clear_bit(pos, bitmap_addr) *(bitmap_addr) &= ~(1UL << (pos))
72 
73 #define KTR_NTB KTR_SPARE3
74 
75 #define NTB_TRANSPORT_VERSION	3
76 #define NTB_RX_MAX_PKTS		64
77 #define	NTB_RXQ_SIZE		300
78 
79 static unsigned int transport_mtu = 0x4000 + ETHER_HDR_LEN + ETHER_CRC_LEN;
80 static unsigned int max_num_clients = 1;
81 
82 STAILQ_HEAD(ntb_queue_list, ntb_queue_entry);
83 
84 struct ntb_queue_entry {
85 	/* ntb_queue list reference */
86 	STAILQ_ENTRY(ntb_queue_entry) entry;
87 
88 	/* info on data to be transfered */
89 	void		*cb_data;
90 	void		*buf;
91 	uint64_t	len;
92 	uint64_t	flags;
93 };
94 
95 struct ntb_rx_info {
96 	unsigned int entry;
97 };
98 
99 struct ntb_transport_qp {
100 	struct ntb_netdev	*transport;
101 	struct ntb_softc	*ntb;
102 
103 	void			*cb_data;
104 
105 	bool			client_ready;
106 	bool			qp_link;
107 	uint8_t			qp_num;	/* Only 64 QP's are allowed.  0-63 */
108 
109 	struct ntb_rx_info	*rx_info;
110 	struct ntb_rx_info	*remote_rx_info;
111 
112 	void (*tx_handler) (struct ntb_transport_qp *qp, void *qp_data,
113 	    void *data, int len);
114 	struct ntb_queue_list	tx_free_q;
115 	struct mtx		ntb_tx_free_q_lock;
116 	void			*tx_mw;
117 	uint64_t		tx_index;
118 	uint64_t		tx_max_entry;
119 	uint64_t		tx_max_frame;
120 
121 	void (*rx_handler) (struct ntb_transport_qp *qp, void *qp_data,
122 	    void *data, int len);
123 	struct ntb_queue_list	rx_pend_q;
124 	struct ntb_queue_list	rx_free_q;
125 	struct mtx		ntb_rx_pend_q_lock;
126 	struct mtx		ntb_rx_free_q_lock;
127 	struct task		rx_completion_task;
128 	void			*rx_buff;
129 	uint64_t		rx_index;
130 	uint64_t		rx_max_entry;
131 	uint64_t		rx_max_frame;
132 
133 	void (*event_handler) (void *data, int status);
134 	struct callout		link_work;
135 	struct callout		queue_full;
136 	struct callout		rx_full;
137 
138 	uint64_t		last_rx_no_buf;
139 
140 	/* Stats */
141 	uint64_t		rx_bytes;
142 	uint64_t		rx_pkts;
143 	uint64_t		rx_ring_empty;
144 	uint64_t		rx_err_no_buf;
145 	uint64_t		rx_err_oflow;
146 	uint64_t		rx_err_ver;
147 	uint64_t		tx_bytes;
148 	uint64_t		tx_pkts;
149 	uint64_t		tx_ring_full;
150 };
151 
152 struct ntb_queue_handlers {
153 	void (*rx_handler) (struct ntb_transport_qp *qp, void *qp_data,
154 	    void *data, int len);
155 	void (*tx_handler) (struct ntb_transport_qp *qp, void *qp_data,
156 	    void *data, int len);
157 	void (*event_handler) (void *data, int status);
158 };
159 
160 
161 struct ntb_transport_mw {
162 	size_t		size;
163 	void		*virt_addr;
164 	vm_paddr_t	dma_addr;
165 };
166 
167 struct ntb_netdev {
168 	struct ntb_softc	*ntb;
169 	struct ifnet		*ifp;
170 	struct ntb_transport_mw	mw[NTB_NUM_MW];
171 	struct ntb_transport_qp	*qps;
172 	uint64_t		max_qps;
173 	uint64_t		qp_bitmap;
174 	bool			transport_link;
175 	struct callout		link_work;
176 	struct ntb_transport_qp *qp;
177 	uint64_t		bufsize;
178 	u_char			eaddr[ETHER_ADDR_LEN];
179 	struct mtx		tx_lock;
180 	struct mtx		rx_lock;
181 };
182 
183 static struct ntb_netdev net_softc;
184 
185 enum {
186 	IF_NTB_DESC_DONE_FLAG = 1 << 0,
187 	IF_NTB_LINK_DOWN_FLAG = 1 << 1,
188 };
189 
190 struct ntb_payload_header {
191 	uint64_t ver;
192 	uint64_t len;
193 	uint64_t flags;
194 };
195 
196 enum {
197 	IF_NTB_VERSION = 0,
198 	IF_NTB_MW0_SZ,
199 	IF_NTB_MW1_SZ,
200 	IF_NTB_NUM_QPS,
201 	IF_NTB_QP_LINKS,
202 	IF_NTB_MAX_SPAD,
203 };
204 
205 #define QP_TO_MW(qp)		((qp) % NTB_NUM_MW)
206 #define NTB_QP_DEF_NUM_ENTRIES	100
207 #define NTB_LINK_DOWN_TIMEOUT	10
208 
209 static int ntb_handle_module_events(struct module *m, int what, void *arg);
210 static int ntb_setup_interface(void);
211 static int ntb_teardown_interface(void);
212 static void ntb_net_init(void *arg);
213 static int ntb_ioctl(struct ifnet *ifp, u_long command, caddr_t data);
214 static void ntb_start(struct ifnet *ifp);
215 static void ntb_net_tx_handler(struct ntb_transport_qp *qp, void *qp_data,
216     void *data, int len);
217 static void ntb_net_rx_handler(struct ntb_transport_qp *qp, void *qp_data,
218     void *data, int len);
219 static void ntb_net_event_handler(void *data, int status);
220 static int ntb_transport_init(struct ntb_softc *ntb);
221 static void ntb_transport_free(void *transport);
222 static void ntb_transport_init_queue(struct ntb_netdev *nt,
223     unsigned int qp_num);
224 static void ntb_transport_free_queue(struct ntb_transport_qp *qp);
225 static struct ntb_transport_qp * ntb_transport_create_queue(void *data,
226     struct ntb_softc *pdev, const struct ntb_queue_handlers *handlers);
227 static void ntb_transport_link_up(struct ntb_transport_qp *qp);
228 static int ntb_transport_tx_enqueue(struct ntb_transport_qp *qp, void *cb,
229     void *data, unsigned int len);
230 static int ntb_process_tx(struct ntb_transport_qp *qp,
231     struct ntb_queue_entry *entry);
232 static void ntb_tx_copy_task(struct ntb_transport_qp *qp,
233     struct ntb_queue_entry *entry, void *offset);
234 static void ntb_qp_full(void *arg);
235 static void ntb_transport_rxc_db(void *data, int db_num);
236 static void ntb_rx_pendq_full(void *arg);
237 static void ntb_transport_rx(struct ntb_transport_qp *qp);
238 static int ntb_process_rxc(struct ntb_transport_qp *qp);
239 static void ntb_rx_copy_task(struct ntb_transport_qp *qp,
240     struct ntb_queue_entry *entry, void *offset);
241 static void ntb_rx_completion_task(void *arg, int pending);
242 static void ntb_transport_event_callback(void *data, enum ntb_hw_event event);
243 static void ntb_transport_link_work(void *arg);
244 static int ntb_set_mw(struct ntb_netdev *nt, int num_mw, unsigned int size);
245 static void ntb_transport_setup_qp_mw(struct ntb_netdev *nt,
246     unsigned int qp_num);
247 static void ntb_qp_link_work(void *arg);
248 static void ntb_transport_link_cleanup(struct ntb_netdev *nt);
249 static void ntb_qp_link_down(struct ntb_transport_qp *qp);
250 static void ntb_qp_link_cleanup(struct ntb_transport_qp *qp);
251 static void ntb_transport_link_down(struct ntb_transport_qp *qp);
252 static void ntb_send_link_down(struct ntb_transport_qp *qp);
253 static void ntb_list_add(struct mtx *lock, struct ntb_queue_entry *entry,
254     struct ntb_queue_list *list);
255 static struct ntb_queue_entry *ntb_list_rm(struct mtx *lock,
256     struct ntb_queue_list *list);
257 static void create_random_local_eui48(u_char *eaddr);
258 static unsigned int ntb_transport_max_size(struct ntb_transport_qp *qp);
259 
260 MALLOC_DEFINE(M_NTB_IF, "if_ntb", "ntb network driver");
261 
262 /* Module setup and teardown */
263 static int
264 ntb_handle_module_events(struct module *m, int what, void *arg)
265 {
266 	int err = 0;
267 
268 	switch (what) {
269 	case MOD_LOAD:
270 		err = ntb_setup_interface();
271 		break;
272 	case MOD_UNLOAD:
273 		err = ntb_teardown_interface();
274 		break;
275 	default:
276 		err = EOPNOTSUPP;
277 		break;
278 	}
279 	return (err);
280 }
281 
282 static moduledata_t ntb_transport_mod = {
283 	"ntb_transport",
284 	ntb_handle_module_events,
285 	NULL
286 };
287 
288 DECLARE_MODULE(ntb_transport, ntb_transport_mod, SI_SUB_KLD, SI_ORDER_ANY);
289 MODULE_DEPEND(ntb_transport, ntb_hw, 1, 1, 1);
290 
291 static int
292 ntb_setup_interface()
293 {
294 	struct ifnet *ifp;
295 	struct ntb_queue_handlers handlers = { ntb_net_rx_handler,
296 	    ntb_net_tx_handler, ntb_net_event_handler };
297 
298 	net_softc.ntb = devclass_get_softc(devclass_find("ntb_hw"), 0);
299 	if (net_softc.ntb == NULL) {
300 		printf("ntb: Can't find devclass\n");
301 		return (ENXIO);
302 	}
303 
304 	ntb_transport_init(net_softc.ntb);
305 
306 	ifp = net_softc.ifp = if_alloc(IFT_ETHER);
307 	if (ifp == NULL) {
308 		printf("ntb: cannot allocate ifnet structure\n");
309 		return (ENOMEM);
310 	}
311 
312 	net_softc.qp = ntb_transport_create_queue(ifp, net_softc.ntb,
313 	    &handlers);
314 	if_initname(ifp, "ntb", 0);
315 	ifp->if_init = ntb_net_init;
316 	ifp->if_softc = &net_softc;
317 	ifp->if_flags = IFF_BROADCAST | IFF_SIMPLEX;
318 	ifp->if_ioctl = ntb_ioctl;
319 	ifp->if_start = ntb_start;
320 	IFQ_SET_MAXLEN(&ifp->if_snd, IFQ_MAXLEN);
321 	ifp->if_snd.ifq_drv_maxlen = IFQ_MAXLEN;
322 	IFQ_SET_READY(&ifp->if_snd);
323 	create_random_local_eui48(net_softc.eaddr);
324 	ether_ifattach(ifp, net_softc.eaddr);
325 	ifp->if_capabilities = IFCAP_HWCSUM | IFCAP_JUMBO_MTU;
326 	ifp->if_capenable = ifp->if_capabilities;
327 
328 	ntb_transport_link_up(net_softc.qp);
329 	net_softc.bufsize = ntb_transport_max_size(net_softc.qp) +
330 	    sizeof(struct ether_header);
331 	return (0);
332 }
333 
334 static int
335 ntb_teardown_interface()
336 {
337 	struct ifnet *ifp = net_softc.ifp;
338 
339 	ntb_transport_link_down(net_softc.qp);
340 
341 	ether_ifdetach(ifp);
342 	if_free(ifp);
343 	ntb_transport_free_queue(net_softc.qp);
344 	ntb_transport_free(&net_softc);
345 
346 	return (0);
347 }
348 
349 /* Network device interface */
350 
351 static void
352 ntb_net_init(void *arg)
353 {
354 	struct ntb_netdev *ntb_softc = arg;
355 	struct ifnet *ifp = ntb_softc->ifp;
356 
357 	ifp->if_drv_flags |= IFF_DRV_RUNNING;
358 	ifp->if_drv_flags &= ~IFF_DRV_OACTIVE;
359 	ifp->if_flags |= IFF_UP;
360 	if_link_state_change(ifp, LINK_STATE_UP);
361 }
362 
363 static int
364 ntb_ioctl(struct ifnet *ifp, u_long command, caddr_t data)
365 {
366 	struct ntb_netdev *nt = ifp->if_softc;
367 	struct ifreq *ifr = (struct ifreq *)data;
368 	int error = 0;
369 
370 	switch (command) {
371 	case SIOCSIFMTU:
372 	    {
373 		if (ifr->ifr_mtu > ntb_transport_max_size(nt->qp) -
374 		    ETHER_HDR_LEN - ETHER_CRC_LEN) {
375 			error = EINVAL;
376 			break;
377 		}
378 
379 		ifp->if_mtu = ifr->ifr_mtu;
380 		break;
381 	    }
382 	default:
383 		error = ether_ioctl(ifp, command, data);
384 		break;
385 	}
386 
387 	return (error);
388 }
389 
390 
391 static void
392 ntb_start(struct ifnet *ifp)
393 {
394 	struct mbuf *m_head;
395 	struct ntb_netdev *nt = ifp->if_softc;
396 	int rc;
397 
398 	mtx_lock(&nt->tx_lock);
399 	ifp->if_drv_flags &= ~IFF_DRV_OACTIVE;
400 	CTR0(KTR_NTB, "TX: ntb_start");
401 	while (!IFQ_DRV_IS_EMPTY(&ifp->if_snd)) {
402 		IFQ_DRV_DEQUEUE(&ifp->if_snd, m_head);
403 		CTR1(KTR_NTB, "TX: start mbuf %p", m_head);
404 		rc = ntb_transport_tx_enqueue(nt->qp, m_head, m_head,
405 			     m_length(m_head, NULL));
406 		if (rc != 0) {
407 			CTR1(KTR_NTB,
408 			    "TX: couldn't tx mbuf %p. Returning to snd q",
409 			    m_head);
410 			if (rc == EAGAIN) {
411 				ifp->if_drv_flags |= IFF_DRV_OACTIVE;
412 				IFQ_DRV_PREPEND(&ifp->if_snd, m_head);
413 				callout_reset(&nt->qp->queue_full, hz / 1000,
414 				    ntb_qp_full, ifp);
415 			}
416 			break;
417 		}
418 
419 	}
420 	mtx_unlock(&nt->tx_lock);
421 }
422 
423 /* Network Device Callbacks */
424 static void
425 ntb_net_tx_handler(struct ntb_transport_qp *qp, void *qp_data, void *data,
426     int len)
427 {
428 
429 	m_freem(data);
430 	CTR1(KTR_NTB, "TX: tx_handler freeing mbuf %p", data);
431 }
432 
433 static void
434 ntb_net_rx_handler(struct ntb_transport_qp *qp, void *qp_data, void *data,
435     int len)
436 {
437 	struct mbuf *m = data;
438 	struct ifnet *ifp = qp_data;
439 
440 	CTR0(KTR_NTB, "RX: rx handler");
441 	(*ifp->if_input)(ifp, m);
442 }
443 
444 static void
445 ntb_net_event_handler(void *data, int status)
446 {
447 
448 }
449 
450 /* Transport Init and teardown */
451 
452 static int
453 ntb_transport_init(struct ntb_softc *ntb)
454 {
455 	struct ntb_netdev *nt = &net_softc;
456 	int rc, i;
457 
458 	nt->max_qps = max_num_clients;
459 	ntb_register_transport(ntb, nt);
460 	mtx_init(&nt->tx_lock, "ntb transport tx", NULL, MTX_DEF);
461 	mtx_init(&nt->rx_lock, "ntb transport rx", NULL, MTX_DEF);
462 
463 	nt->qps = malloc(nt->max_qps * sizeof(struct ntb_transport_qp),
464 			  M_NTB_IF, M_WAITOK|M_ZERO);
465 
466 	nt->qp_bitmap = ((uint64_t) 1 << nt->max_qps) - 1;
467 
468 	for (i = 0; i < nt->max_qps; i++)
469 		ntb_transport_init_queue(nt, i);
470 
471 	callout_init(&nt->link_work, 0);
472 
473 	rc = ntb_register_event_callback(ntb,
474 					 ntb_transport_event_callback);
475 	if (rc != 0)
476 		goto err;
477 
478 	if (ntb_query_link_status(ntb))
479 		callout_reset(&nt->link_work, 0, ntb_transport_link_work, nt);
480 
481 	return (0);
482 
483 err:
484 	free(nt->qps, M_NTB_IF);
485 	ntb_unregister_transport(ntb);
486 	return (rc);
487 }
488 
489 static void
490 ntb_transport_free(void *transport)
491 {
492 	struct ntb_netdev *nt = transport;
493 	struct ntb_softc *ntb = nt->ntb;
494 	int i;
495 
496 	nt->transport_link = NTB_LINK_DOWN;
497 
498 	callout_drain(&nt->link_work);
499 
500 	/* verify that all the qp's are freed */
501 	for (i = 0; i < nt->max_qps; i++)
502 		if (!test_bit(i, &nt->qp_bitmap))
503 			ntb_transport_free_queue(&nt->qps[i]);
504 
505 
506 	ntb_unregister_event_callback(ntb);
507 
508 	for (i = 0; i < NTB_NUM_MW; i++)
509 		if (nt->mw[i].virt_addr != NULL)
510 			contigfree(nt->mw[i].virt_addr, nt->mw[i].size,
511 					  M_NTB_IF);
512 
513 	free(nt->qps, M_NTB_IF);
514 	ntb_unregister_transport(ntb);
515 }
516 
517 static void
518 ntb_transport_init_queue(struct ntb_netdev *nt, unsigned int qp_num)
519 {
520 	struct ntb_transport_qp *qp;
521 	unsigned int num_qps_mw, tx_size;
522 	uint8_t mw_num = QP_TO_MW(qp_num);
523 
524 	qp = &nt->qps[qp_num];
525 	qp->qp_num = qp_num;
526 	qp->transport = nt;
527 	qp->ntb = nt->ntb;
528 	qp->qp_link = NTB_LINK_DOWN;
529 	qp->client_ready = NTB_LINK_DOWN;
530 	qp->event_handler = NULL;
531 
532 	if (nt->max_qps % NTB_NUM_MW && mw_num < nt->max_qps % NTB_NUM_MW)
533 		num_qps_mw = nt->max_qps / NTB_NUM_MW + 1;
534 	else
535 		num_qps_mw = nt->max_qps / NTB_NUM_MW;
536 
537 	tx_size = (unsigned int) ntb_get_mw_size(qp->ntb, mw_num) / num_qps_mw;
538 	qp->rx_info = (struct ntb_rx_info *)
539 	    ((char *)ntb_get_mw_vbase(qp->ntb, mw_num) +
540 	    (qp_num / NTB_NUM_MW * tx_size));
541 	tx_size -= sizeof(struct ntb_rx_info);
542 
543 	qp->tx_mw = qp->rx_info + sizeof(struct ntb_rx_info);
544 	qp->tx_max_frame = min(transport_mtu + sizeof(struct ntb_payload_header),
545 	    tx_size);
546 	qp->tx_max_entry = tx_size / qp->tx_max_frame;
547 	qp->tx_index = 0;
548 
549 	callout_init(&qp->link_work, 0);
550 	callout_init(&qp->queue_full, CALLOUT_MPSAFE);
551 	callout_init(&qp->rx_full, CALLOUT_MPSAFE);
552 
553 	mtx_init(&qp->ntb_rx_pend_q_lock, "ntb rx pend q", NULL, MTX_SPIN);
554 	mtx_init(&qp->ntb_rx_free_q_lock, "ntb rx free q", NULL, MTX_SPIN);
555 	mtx_init(&qp->ntb_tx_free_q_lock, "ntb tx free q", NULL, MTX_SPIN);
556 	TASK_INIT(&qp->rx_completion_task, 0, ntb_rx_completion_task, qp);
557 
558 	STAILQ_INIT(&qp->rx_pend_q);
559 	STAILQ_INIT(&qp->rx_free_q);
560 	STAILQ_INIT(&qp->tx_free_q);
561 }
562 
563 static void
564 ntb_transport_free_queue(struct ntb_transport_qp *qp)
565 {
566 	struct ntb_queue_entry *entry;
567 
568 	if (qp == NULL)
569 		return;
570 
571 	callout_drain(&qp->link_work);
572 
573 	ntb_unregister_db_callback(qp->ntb, qp->qp_num);
574 
575 	while ((entry = ntb_list_rm(&qp->ntb_rx_free_q_lock, &qp->rx_free_q)))
576 		free(entry, M_NTB_IF);
577 
578 	while ((entry = ntb_list_rm(&qp->ntb_rx_pend_q_lock, &qp->rx_pend_q)))
579 		free(entry, M_NTB_IF);
580 
581 	while ((entry = ntb_list_rm(&qp->ntb_tx_free_q_lock, &qp->tx_free_q)))
582 		free(entry, M_NTB_IF);
583 
584 	set_bit(qp->qp_num, &qp->transport->qp_bitmap);
585 }
586 
587 /**
588  * ntb_transport_create_queue - Create a new NTB transport layer queue
589  * @rx_handler: receive callback function
590  * @tx_handler: transmit callback function
591  * @event_handler: event callback function
592  *
593  * Create a new NTB transport layer queue and provide the queue with a callback
594  * routine for both transmit and receive.  The receive callback routine will be
595  * used to pass up data when the transport has received it on the queue.   The
596  * transmit callback routine will be called when the transport has completed the
597  * transmission of the data on the queue and the data is ready to be freed.
598  *
599  * RETURNS: pointer to newly created ntb_queue, NULL on error.
600  */
601 static struct ntb_transport_qp *
602 ntb_transport_create_queue(void *data, struct ntb_softc *pdev,
603     const struct ntb_queue_handlers *handlers)
604 {
605 	struct ntb_queue_entry *entry;
606 	struct ntb_transport_qp *qp;
607 	struct ntb_netdev *nt;
608 	unsigned int free_queue;
609 	int rc, i;
610 
611 	nt = ntb_find_transport(pdev);
612 	if (nt == NULL)
613 		goto err;
614 
615 	free_queue = ffs(nt->qp_bitmap);
616 	if (free_queue == 0)
617 		goto err;
618 
619 	/* decrement free_queue to make it zero based */
620 	free_queue--;
621 
622 	clear_bit(free_queue, &nt->qp_bitmap);
623 
624 	qp = &nt->qps[free_queue];
625 	qp->cb_data = data;
626 	qp->rx_handler = handlers->rx_handler;
627 	qp->tx_handler = handlers->tx_handler;
628 	qp->event_handler = handlers->event_handler;
629 
630 	for (i = 0; i < NTB_QP_DEF_NUM_ENTRIES; i++) {
631 		entry = malloc(sizeof(struct ntb_queue_entry), M_NTB_IF,
632 		    M_WAITOK|M_ZERO);
633 		entry->cb_data = nt->ifp;
634 		entry->buf = NULL;
635 		entry->len = transport_mtu;
636 		ntb_list_add(&qp->ntb_rx_pend_q_lock, entry, &qp->rx_pend_q);
637 	}
638 
639 	for (i = 0; i < NTB_QP_DEF_NUM_ENTRIES; i++) {
640 		entry = malloc(sizeof(struct ntb_queue_entry), M_NTB_IF,
641 		    M_WAITOK|M_ZERO);
642 		ntb_list_add(&qp->ntb_tx_free_q_lock, entry, &qp->tx_free_q);
643 	}
644 
645 	rc = ntb_register_db_callback(qp->ntb, free_queue, qp,
646 				      ntb_transport_rxc_db);
647 	if (rc != 0)
648 		goto err1;
649 
650 	return (qp);
651 
652 err1:
653 	while ((entry = ntb_list_rm(&qp->ntb_tx_free_q_lock, &qp->tx_free_q)))
654 		free(entry, M_NTB_IF);
655 	while ((entry = ntb_list_rm(&qp->ntb_rx_free_q_lock, &qp->rx_free_q)))
656 		free(entry, M_NTB_IF);
657 	set_bit(free_queue, &nt->qp_bitmap);
658 err:
659 	return (NULL);
660 }
661 
662 /**
663  * ntb_transport_link_up - Notify NTB transport of client readiness to use queue
664  * @qp: NTB transport layer queue to be enabled
665  *
666  * Notify NTB transport layer of client readiness to use queue
667  */
668 static void
669 ntb_transport_link_up(struct ntb_transport_qp *qp)
670 {
671 
672 	if (qp == NULL)
673 		return;
674 
675 	qp->client_ready = NTB_LINK_UP;
676 
677 	if (qp->transport->transport_link == NTB_LINK_UP)
678 		callout_reset(&qp->link_work, 0, ntb_qp_link_work, qp);
679 }
680 
681 
682 
683 /* Transport Tx */
684 
685 /**
686  * ntb_transport_tx_enqueue - Enqueue a new NTB queue entry
687  * @qp: NTB transport layer queue the entry is to be enqueued on
688  * @cb: per buffer pointer for callback function to use
689  * @data: pointer to data buffer that will be sent
690  * @len: length of the data buffer
691  *
692  * Enqueue a new transmit buffer onto the transport queue from which a NTB
693  * payload will be transmitted.  This assumes that a lock is behing held to
694  * serialize access to the qp.
695  *
696  * RETURNS: An appropriate ERRNO error value on error, or zero for success.
697  */
698 static int
699 ntb_transport_tx_enqueue(struct ntb_transport_qp *qp, void *cb, void *data,
700     unsigned int len)
701 {
702 	struct ntb_queue_entry *entry;
703 	int rc;
704 
705 	if (qp == NULL || qp->qp_link != NTB_LINK_UP || len == 0) {
706 		CTR0(KTR_NTB, "TX: link not up");
707 		return (EINVAL);
708 	}
709 
710 	entry = ntb_list_rm(&qp->ntb_tx_free_q_lock, &qp->tx_free_q);
711 	if (entry == NULL) {
712 		CTR0(KTR_NTB, "TX: couldn't get entry from tx_free_q");
713 		return (ENOMEM);
714 	}
715 	CTR1(KTR_NTB, "TX: got entry %p from tx_free_q", entry);
716 
717 	entry->cb_data = cb;
718 	entry->buf = data;
719 	entry->len = len;
720 	entry->flags = 0;
721 
722 	rc = ntb_process_tx(qp, entry);
723 	if (rc != 0) {
724 		ntb_list_add(&qp->ntb_tx_free_q_lock, entry, &qp->tx_free_q);
725 		CTR1(KTR_NTB,
726 		    "TX: process_tx failed. Returning entry %p to tx_free_q",
727 		    entry);
728 	}
729 	return (rc);
730 }
731 
732 static int
733 ntb_process_tx(struct ntb_transport_qp *qp, struct ntb_queue_entry *entry)
734 {
735 	void *offset;
736 
737 	offset = (char *)qp->tx_mw + qp->tx_max_frame * qp->tx_index;
738 	CTR3(KTR_NTB,
739 	    "TX: process_tx: tx_pkts=%u, tx_index=%u, remote entry=%u",
740 	    qp->tx_pkts, qp->tx_index, qp->remote_rx_info->entry);
741 	if (qp->tx_index == qp->remote_rx_info->entry) {
742 		CTR0(KTR_NTB, "TX: ring full");
743 		qp->tx_ring_full++;
744 		return (EAGAIN);
745 	}
746 
747 	if (entry->len > qp->tx_max_frame - sizeof(struct ntb_payload_header)) {
748 		if (qp->tx_handler != NULL)
749 			qp->tx_handler(qp, qp->cb_data, entry->buf,
750 				       EIO);
751 
752 		ntb_list_add(&qp->ntb_tx_free_q_lock, entry, &qp->tx_free_q);
753 		CTR1(KTR_NTB,
754 		    "TX: frame too big. returning entry %p to tx_free_q",
755 		    entry);
756 		return (0);
757 	}
758 	CTR2(KTR_NTB, "TX: copying entry %p to offset %p", entry, offset);
759 	ntb_tx_copy_task(qp, entry, offset);
760 
761 	qp->tx_index++;
762 	qp->tx_index %= qp->tx_max_entry;
763 
764 	qp->tx_pkts++;
765 
766 	return (0);
767 }
768 
769 static void
770 ntb_tx_copy_task(struct ntb_transport_qp *qp, struct ntb_queue_entry *entry,
771     void *offset)
772 {
773 	struct ntb_payload_header *hdr;
774 
775 	CTR2(KTR_NTB, "TX: copying %d bytes to offset %p", entry->len, offset);
776 	if (entry->buf != NULL)
777 		m_copydata((struct mbuf *)entry->buf, 0, entry->len, offset);
778 
779 	hdr = (struct ntb_payload_header *)((char *)offset + qp->tx_max_frame -
780 	    sizeof(struct ntb_payload_header));
781 	hdr->len = entry->len; /* TODO: replace with bus_space_write */
782 	hdr->ver = qp->tx_pkts; /* TODO: replace with bus_space_write */
783 	wmb();
784 	/* TODO: replace with bus_space_write */
785 	hdr->flags = entry->flags | IF_NTB_DESC_DONE_FLAG;
786 
787 	ntb_ring_sdb(qp->ntb, qp->qp_num);
788 
789 	/*
790 	 * The entry length can only be zero if the packet is intended to be a
791 	 * "link down" or similar.  Since no payload is being sent in these
792 	 * cases, there is nothing to add to the completion queue.
793 	 */
794 	if (entry->len > 0) {
795 		qp->tx_bytes += entry->len;
796 
797 		if (qp->tx_handler)
798 			qp->tx_handler(qp, qp->cb_data, entry->cb_data,
799 				       entry->len);
800 	}
801 
802 	CTR2(KTR_NTB,
803 	    "TX: entry %p sent. hdr->ver = %d, Returning to tx_free_q", entry,
804 	    hdr->ver);
805 	ntb_list_add(&qp->ntb_tx_free_q_lock, entry, &qp->tx_free_q);
806 }
807 
808 static void
809 ntb_qp_full(void *arg)
810 {
811 
812 	CTR0(KTR_NTB, "TX: qp_full callout");
813 	ntb_start(arg);
814 }
815 
816 /* Transport Rx */
817 static void
818 ntb_transport_rxc_db(void *data, int db_num)
819 {
820 	struct ntb_transport_qp *qp = data;
821 
822 	ntb_transport_rx(qp);
823 }
824 
825 static void
826 ntb_rx_pendq_full(void *arg)
827 {
828 
829 	CTR0(KTR_NTB, "RX: ntb_rx_pendq_full callout");
830 	ntb_transport_rx(arg);
831 }
832 
833 static void
834 ntb_transport_rx(struct ntb_transport_qp *qp)
835 {
836 	int rc, i;
837 
838 	/*
839 	 * Limit the number of packets processed in a single interrupt to
840 	 * provide fairness to others
841 	 */
842 	mtx_lock(&qp->transport->rx_lock);
843 	CTR0(KTR_NTB, "RX: transport_rx");
844 	for (i = 0; i < NTB_RX_MAX_PKTS; i++) {
845 		rc = ntb_process_rxc(qp);
846 		if (rc != 0) {
847 			CTR0(KTR_NTB, "RX: process_rxc failed");
848 			break;
849 		}
850 	}
851 	mtx_unlock(&qp->transport->rx_lock);
852 }
853 
854 static int
855 ntb_process_rxc(struct ntb_transport_qp *qp)
856 {
857 	struct ntb_payload_header *hdr;
858 	struct ntb_queue_entry *entry;
859 	void *offset;
860 
861 	offset = (void *)
862 	    ((char *)qp->rx_buff + qp->rx_max_frame * qp->rx_index);
863 	hdr = (void *)
864 	    ((char *)offset + qp->rx_max_frame -
865 		sizeof(struct ntb_payload_header));
866 
867 	CTR1(KTR_NTB, "RX: process_rxc rx_index = %u", qp->rx_index);
868 	entry = ntb_list_rm(&qp->ntb_rx_pend_q_lock, &qp->rx_pend_q);
869 	if (entry == NULL) {
870 		qp->rx_err_no_buf++;
871 		CTR0(KTR_NTB, "RX: No entries in rx_pend_q");
872 		return (ENOMEM);
873 	}
874 	callout_stop(&qp->rx_full);
875 	CTR1(KTR_NTB, "RX: rx entry %p from rx_pend_q", entry);
876 
877 	if ((hdr->flags & IF_NTB_DESC_DONE_FLAG) == 0) {
878 		CTR1(KTR_NTB,
879 		    "RX: hdr not done. Returning entry %p to rx_pend_q", entry);
880 		ntb_list_add(&qp->ntb_rx_pend_q_lock, entry, &qp->rx_pend_q);
881 		qp->rx_ring_empty++;
882 		return (EAGAIN);
883 	}
884 
885 	if (hdr->ver != (uint32_t) qp->rx_pkts) {
886 		CTR3(KTR_NTB,"RX: ver != rx_pkts (%x != %lx). "
887 		    "Returning entry %p to rx_pend_q", hdr->ver, qp->rx_pkts,
888 		    entry);
889 		ntb_list_add(&qp->ntb_rx_pend_q_lock, entry, &qp->rx_pend_q);
890 		qp->rx_err_ver++;
891 		return (EIO);
892 	}
893 
894 	if ((hdr->flags & IF_NTB_LINK_DOWN_FLAG) != 0) {
895 		ntb_qp_link_down(qp);
896 		CTR1(KTR_NTB,
897 		    "RX: link down. adding entry %p back to rx_pend_q", entry);
898 		ntb_list_add(&qp->ntb_rx_pend_q_lock, entry, &qp->rx_pend_q);
899 		goto out;
900 	}
901 
902 	if (hdr->len <= entry->len) {
903 		entry->len = hdr->len;
904 		ntb_rx_copy_task(qp, entry, offset);
905 	} else {
906 		CTR1(KTR_NTB,
907 		    "RX: len too long. Returning entry %p to rx_pend_q", entry);
908 		ntb_list_add(&qp->ntb_rx_pend_q_lock, entry, &qp->rx_pend_q);
909 
910 		qp->rx_err_oflow++;
911 	}
912 
913 	qp->rx_bytes += hdr->len;
914 	qp->rx_pkts++;
915 	CTR1(KTR_NTB, "RX: received %ld rx_pkts", qp->rx_pkts);
916 
917 
918 out:
919 	/* Ensure that the data is globally visible before clearing the flag */
920 	wmb();
921 	hdr->flags = 0;
922 	/* TODO: replace with bus_space_write */
923 	qp->rx_info->entry = qp->rx_index;
924 
925 	qp->rx_index++;
926 	qp->rx_index %= qp->rx_max_entry;
927 
928 	return (0);
929 }
930 
931 static void
932 ntb_rx_copy_task(struct ntb_transport_qp *qp, struct ntb_queue_entry *entry,
933     void *offset)
934 {
935 	struct ifnet *ifp = entry->cb_data;
936 	unsigned int len = entry->len;
937 	struct mbuf *m;
938 
939 	CTR2(KTR_NTB, "RX: copying %d bytes from offset %p", len, offset);
940 	m = m_devget(offset, len, 0, ifp, NULL);
941 	m->m_pkthdr.csum_flags = CSUM_IP_CHECKED | CSUM_IP_VALID;
942 
943 	entry->buf = (void *)m;
944 
945 	CTR2(KTR_NTB,
946 	    "RX: copied entry %p to mbuf %p. Adding entry to rx_free_q", entry,
947 	    m);
948 	ntb_list_add(&qp->ntb_rx_free_q_lock, entry, &qp->rx_free_q);
949 
950 	taskqueue_enqueue(taskqueue_swi, &qp->rx_completion_task);
951 }
952 
953 static void
954 ntb_rx_completion_task(void *arg, int pending)
955 {
956 	struct ntb_transport_qp *qp = arg;
957 	struct mbuf *m;
958 	struct ntb_queue_entry *entry;
959 
960 	CTR0(KTR_NTB, "RX: rx_completion_task");
961 
962 	while ((entry = ntb_list_rm(&qp->ntb_rx_free_q_lock, &qp->rx_free_q))) {
963 		m = entry->buf;
964 		CTR2(KTR_NTB, "RX: completing entry %p, mbuf %p", entry, m);
965 		if (qp->rx_handler && qp->client_ready == NTB_LINK_UP)
966 			qp->rx_handler(qp, qp->cb_data, m, entry->len);
967 
968 		entry->buf = NULL;
969 		entry->len = qp->transport->bufsize;
970 
971 		CTR1(KTR_NTB,"RX: entry %p removed from rx_free_q "
972 		    "and added to rx_pend_q", entry);
973 		ntb_list_add(&qp->ntb_rx_pend_q_lock, entry, &qp->rx_pend_q);
974 		if (qp->rx_err_no_buf > qp->last_rx_no_buf) {
975 			qp->last_rx_no_buf = qp->rx_err_no_buf;
976 			CTR0(KTR_NTB, "RX: could spawn rx task");
977 			callout_reset(&qp->rx_full, hz / 1000, ntb_rx_pendq_full,
978 			    qp);
979 		}
980 	}
981 }
982 
983 /* Link Event handler */
984 static void
985 ntb_transport_event_callback(void *data, enum ntb_hw_event event)
986 {
987 	struct ntb_netdev *nt = data;
988 
989 	switch (event) {
990 	case NTB_EVENT_HW_LINK_UP:
991 		callout_reset(&nt->link_work, 0, ntb_transport_link_work, nt);
992 		break;
993 	case NTB_EVENT_HW_LINK_DOWN:
994 		ntb_transport_link_cleanup(nt);
995 		break;
996 	default:
997 		panic("ntb: Unknown NTB event");
998 	}
999 }
1000 
1001 /* Link bring up */
1002 static void
1003 ntb_transport_link_work(void *arg)
1004 {
1005 	struct ntb_netdev *nt = arg;
1006 	struct ntb_softc *ntb = nt->ntb;
1007 	struct ntb_transport_qp *qp;
1008 	uint32_t val;
1009 	int rc, i;
1010 
1011 	/* send the local info */
1012 	rc = ntb_write_remote_spad(ntb, IF_NTB_VERSION, NTB_TRANSPORT_VERSION);
1013 	if (rc != 0)
1014 		goto out;
1015 
1016 	rc = ntb_write_remote_spad(ntb, IF_NTB_MW0_SZ, ntb_get_mw_size(ntb, 0));
1017 	if (rc != 0)
1018 		goto out;
1019 
1020 	rc = ntb_write_remote_spad(ntb, IF_NTB_MW1_SZ, ntb_get_mw_size(ntb, 1));
1021 	if (rc != 0)
1022 		goto out;
1023 
1024 	rc = ntb_write_remote_spad(ntb, IF_NTB_NUM_QPS, nt->max_qps);
1025 	if (rc != 0)
1026 		goto out;
1027 
1028 	rc = ntb_read_remote_spad(ntb, IF_NTB_QP_LINKS, &val);
1029 	if (rc != 0)
1030 		goto out;
1031 
1032 	rc = ntb_write_remote_spad(ntb, IF_NTB_QP_LINKS, val);
1033 	if (rc != 0)
1034 		goto out;
1035 
1036 	/* Query the remote side for its info */
1037 	rc = ntb_read_local_spad(ntb, IF_NTB_VERSION, &val);
1038 	if (rc != 0)
1039 		goto out;
1040 
1041 	if (val != NTB_TRANSPORT_VERSION)
1042 		goto out;
1043 
1044 	rc = ntb_read_local_spad(ntb, IF_NTB_NUM_QPS, &val);
1045 	if (rc != 0)
1046 		goto out;
1047 
1048 	if (val != nt->max_qps)
1049 		goto out;
1050 
1051 	rc = ntb_read_local_spad(ntb, IF_NTB_MW0_SZ, &val);
1052 	if (rc != 0)
1053 		goto out;
1054 
1055 	if (val == 0)
1056 		goto out;
1057 
1058 	rc = ntb_set_mw(nt, 0, val);
1059 	if (rc != 0)
1060 		return;
1061 
1062 	rc = ntb_read_local_spad(ntb, IF_NTB_MW1_SZ, &val);
1063 	if (rc != 0)
1064 		goto out;
1065 
1066 	if (val == 0)
1067 		goto out;
1068 
1069 	rc = ntb_set_mw(nt, 1, val);
1070 	if (rc != 0)
1071 		return;
1072 
1073 	nt->transport_link = NTB_LINK_UP;
1074 
1075 	for (i = 0; i < nt->max_qps; i++) {
1076 		qp = &nt->qps[i];
1077 
1078 		ntb_transport_setup_qp_mw(nt, i);
1079 
1080 		if (qp->client_ready == NTB_LINK_UP)
1081 			callout_reset(&qp->link_work, 0, ntb_qp_link_work, qp);
1082 	}
1083 
1084 	return;
1085 
1086 out:
1087 	if (ntb_query_link_status(ntb))
1088 		callout_reset(&nt->link_work,
1089 				      NTB_LINK_DOWN_TIMEOUT * hz / 1000, ntb_transport_link_work, nt);
1090 }
1091 
1092 static int
1093 ntb_set_mw(struct ntb_netdev *nt, int num_mw, unsigned int size)
1094 {
1095 	struct ntb_transport_mw *mw = &nt->mw[num_mw];
1096 
1097 	/* Alloc memory for receiving data.  Must be 4k aligned */
1098 	mw->size = size;
1099 
1100 	mw->virt_addr = contigmalloc(mw->size, M_NTB_IF, M_ZERO, 0,
1101 	    BUS_SPACE_MAXADDR, mw->size, 0);
1102 	if (mw->virt_addr == NULL) {
1103 		printf("ntb: Unable to allocate MW buffer of size %d\n",
1104 		    (int)mw->size);
1105 		return (ENOMEM);
1106 	}
1107 	/* TODO: replace with bus_space_* functions */
1108 	mw->dma_addr = vtophys(mw->virt_addr);
1109 
1110 	/* Notify HW the memory location of the receive buffer */
1111 	ntb_set_mw_addr(nt->ntb, num_mw, mw->dma_addr);
1112 
1113 	return (0);
1114 }
1115 
1116 static void
1117 ntb_transport_setup_qp_mw(struct ntb_netdev *nt, unsigned int qp_num)
1118 {
1119 	struct ntb_transport_qp *qp = &nt->qps[qp_num];
1120 	void *offset;
1121 	unsigned int rx_size, num_qps_mw;
1122 	uint8_t mw_num = QP_TO_MW(qp_num);
1123 	unsigned int i;
1124 
1125 	if (nt->max_qps % NTB_NUM_MW && mw_num < nt->max_qps % NTB_NUM_MW)
1126 		num_qps_mw = nt->max_qps / NTB_NUM_MW + 1;
1127 	else
1128 		num_qps_mw = nt->max_qps / NTB_NUM_MW;
1129 
1130 	rx_size = (unsigned int) nt->mw[mw_num].size / num_qps_mw;
1131 	qp->remote_rx_info = (void *)((uint8_t *)nt->mw[mw_num].virt_addr +
1132 			     (qp_num / NTB_NUM_MW * rx_size));
1133 	rx_size -= sizeof(struct ntb_rx_info);
1134 
1135 	qp->rx_buff = qp->remote_rx_info + sizeof(struct ntb_rx_info);
1136 	qp->rx_max_frame = min(transport_mtu + sizeof(struct ntb_payload_header),
1137 	    rx_size);
1138 	qp->rx_max_entry = rx_size / qp->rx_max_frame;
1139 	qp->rx_index = 0;
1140 	qp->tx_index = 0;
1141 
1142 	qp->remote_rx_info->entry = qp->rx_max_entry;
1143 
1144 	/* setup the hdr offsets with 0's */
1145 	for (i = 0; i < qp->rx_max_entry; i++) {
1146 		offset = (void *)((uint8_t *)qp->rx_buff +
1147 		    qp->rx_max_frame * (i + 1) -
1148 		    sizeof(struct ntb_payload_header));
1149 		memset(offset, 0, sizeof(struct ntb_payload_header));
1150 	}
1151 
1152 	qp->rx_pkts = 0;
1153 	qp->tx_pkts = 0;
1154 }
1155 
1156 static void
1157 ntb_qp_link_work(void *arg)
1158 {
1159 	struct ntb_transport_qp *qp = arg;
1160 	struct ntb_softc *ntb = qp->ntb;
1161 	struct ntb_netdev *nt = qp->transport;
1162 	int rc, val;
1163 
1164 
1165 	rc = ntb_read_remote_spad(ntb, IF_NTB_QP_LINKS, &val);
1166 	if (rc != 0)
1167 		return;
1168 
1169 	rc = ntb_write_remote_spad(ntb, IF_NTB_QP_LINKS, val | 1 << qp->qp_num);
1170 
1171 	/* query remote spad for qp ready bits */
1172 	rc = ntb_read_local_spad(ntb, IF_NTB_QP_LINKS, &val);
1173 
1174 	/* See if the remote side is up */
1175 	if ((1 << qp->qp_num & val) != 0) {
1176 		qp->qp_link = NTB_LINK_UP;
1177 		if (qp->event_handler != NULL)
1178 			qp->event_handler(qp->cb_data, NTB_LINK_UP);
1179 	} else if (nt->transport_link == NTB_LINK_UP) {
1180 		callout_reset(&qp->link_work,
1181 		    NTB_LINK_DOWN_TIMEOUT * hz / 1000, ntb_qp_link_work, qp);
1182 	}
1183 }
1184 
1185 /* Link down event*/
1186 static void
1187 ntb_transport_link_cleanup(struct ntb_netdev *nt)
1188 {
1189 	int i;
1190 
1191 	if (nt->transport_link == NTB_LINK_DOWN)
1192 		callout_drain(&nt->link_work);
1193 	else
1194 		nt->transport_link = NTB_LINK_DOWN;
1195 
1196 	/* Pass along the info to any clients */
1197 	for (i = 0; i < nt->max_qps; i++)
1198 		if (!test_bit(i, &nt->qp_bitmap))
1199 			ntb_qp_link_down(&nt->qps[i]);
1200 
1201 	/*
1202 	 * The scratchpad registers keep the values if the remote side
1203 	 * goes down, blast them now to give them a sane value the next
1204 	 * time they are accessed
1205 	 */
1206 	for (i = 0; i < IF_NTB_MAX_SPAD; i++)
1207 		ntb_write_local_spad(nt->ntb, i, 0);
1208 }
1209 
1210 
1211 static void
1212 ntb_qp_link_down(struct ntb_transport_qp *qp)
1213 {
1214 
1215 	ntb_qp_link_cleanup(qp);
1216 }
1217 
1218 static void
1219 ntb_qp_link_cleanup(struct ntb_transport_qp *qp)
1220 {
1221 	struct ntb_netdev *nt = qp->transport;
1222 
1223 	if (qp->qp_link == NTB_LINK_DOWN) {
1224 		callout_drain(&qp->link_work);
1225 		return;
1226 	}
1227 
1228 	if (qp->event_handler != NULL)
1229 		qp->event_handler(qp->cb_data, NTB_LINK_DOWN);
1230 
1231 	qp->qp_link = NTB_LINK_DOWN;
1232 
1233 	if (nt->transport_link == NTB_LINK_UP)
1234 		callout_reset(&qp->link_work,
1235 		    NTB_LINK_DOWN_TIMEOUT * hz / 1000, ntb_qp_link_work, qp);
1236 }
1237 
1238 /* Link commanded down */
1239 /**
1240  * ntb_transport_link_down - Notify NTB transport to no longer enqueue data
1241  * @qp: NTB transport layer queue to be disabled
1242  *
1243  * Notify NTB transport layer of client's desire to no longer receive data on
1244  * transport queue specified.  It is the client's responsibility to ensure all
1245  * entries on queue are purged or otherwise handled appropraitely.
1246  */
1247 static void
1248 ntb_transport_link_down(struct ntb_transport_qp *qp)
1249 {
1250 	int rc, val;
1251 
1252 	if (qp == NULL)
1253 		return;
1254 
1255 	qp->client_ready = NTB_LINK_DOWN;
1256 
1257 	rc = ntb_read_remote_spad(qp->ntb, IF_NTB_QP_LINKS, &val);
1258 	if (rc != 0)
1259 		return;
1260 
1261 	rc = ntb_write_remote_spad(qp->ntb, IF_NTB_QP_LINKS,
1262 	   val & ~(1 << qp->qp_num));
1263 
1264 	if (qp->qp_link == NTB_LINK_UP)
1265 		ntb_send_link_down(qp);
1266 	else
1267 		callout_drain(&qp->link_work);
1268 
1269 }
1270 
1271 static void
1272 ntb_send_link_down(struct ntb_transport_qp *qp)
1273 {
1274 	struct ntb_queue_entry *entry;
1275 	int i, rc;
1276 
1277 	if (qp->qp_link == NTB_LINK_DOWN)
1278 		return;
1279 
1280 	qp->qp_link = NTB_LINK_DOWN;
1281 
1282 	for (i = 0; i < NTB_LINK_DOWN_TIMEOUT; i++) {
1283 		entry = ntb_list_rm(&qp->ntb_tx_free_q_lock, &qp->tx_free_q);
1284 		if (entry != NULL)
1285 			break;
1286 		pause("NTB Wait for link down", hz / 10);
1287 	}
1288 
1289 	if (entry == NULL)
1290 		return;
1291 
1292 	entry->cb_data = NULL;
1293 	entry->buf = NULL;
1294 	entry->len = 0;
1295 	entry->flags = IF_NTB_LINK_DOWN_FLAG;
1296 
1297 	mtx_lock(&qp->transport->tx_lock);
1298 	rc = ntb_process_tx(qp, entry);
1299 	if (rc != 0)
1300 		printf("ntb: Failed to send link down\n");
1301 	mtx_unlock(&qp->transport->tx_lock);
1302 }
1303 
1304 
1305 /* List Management */
1306 
1307 static void
1308 ntb_list_add(struct mtx *lock, struct ntb_queue_entry *entry,
1309     struct ntb_queue_list *list)
1310 {
1311 
1312 	mtx_lock_spin(lock);
1313 	STAILQ_INSERT_TAIL(list, entry, entry);
1314 	mtx_unlock_spin(lock);
1315 }
1316 
1317 static struct ntb_queue_entry *
1318 ntb_list_rm(struct mtx *lock, struct ntb_queue_list *list)
1319 {
1320 	struct ntb_queue_entry *entry;
1321 
1322 	mtx_lock_spin(lock);
1323 	if (STAILQ_EMPTY(list)) {
1324 		entry = NULL;
1325 		goto out;
1326 	}
1327 	entry = STAILQ_FIRST(list);
1328 	STAILQ_REMOVE_HEAD(list, entry);
1329 out:
1330 	mtx_unlock_spin(lock);
1331 
1332 	return (entry);
1333 }
1334 
1335 /* Helper functions */
1336 /* TODO: This too should really be part of the kernel */
1337 #define EUI48_MULTICAST			1 << 0
1338 #define EUI48_LOCALLY_ADMINISTERED	1 << 1
1339 static void
1340 create_random_local_eui48(u_char *eaddr)
1341 {
1342 	static uint8_t counter = 0;
1343 	uint32_t seed = ticks;
1344 
1345 	eaddr[0] = EUI48_LOCALLY_ADMINISTERED;
1346 	memcpy(&eaddr[1], &seed, sizeof(uint32_t));
1347 	eaddr[5] = counter++;
1348 }
1349 
1350 /**
1351  * ntb_transport_max_size - Query the max payload size of a qp
1352  * @qp: NTB transport layer queue to be queried
1353  *
1354  * Query the maximum payload size permissible on the given qp
1355  *
1356  * RETURNS: the max payload size of a qp
1357  */
1358 static unsigned int
1359 ntb_transport_max_size(struct ntb_transport_qp *qp)
1360 {
1361 
1362 	if (qp == NULL)
1363 		return (0);
1364 
1365 	return (qp->tx_max_frame - sizeof(struct ntb_payload_header));
1366 }
1367