xref: /freebsd/sys/dev/ioat/ioat.c (revision 11b249f99e4d4891bd2a21ef796d40073ee15508)
1 /*-
2  * Copyright (C) 2012 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/systm.h>
32 #include <sys/bus.h>
33 #include <sys/conf.h>
34 #include <sys/ioccom.h>
35 #include <sys/kernel.h>
36 #include <sys/lock.h>
37 #include <sys/malloc.h>
38 #include <sys/module.h>
39 #include <sys/mutex.h>
40 #include <sys/rman.h>
41 #include <sys/sbuf.h>
42 #include <sys/sysctl.h>
43 #include <sys/time.h>
44 #include <dev/pci/pcireg.h>
45 #include <dev/pci/pcivar.h>
46 #include <machine/bus.h>
47 #include <machine/resource.h>
48 #include <machine/stdarg.h>
49 
50 #include "ioat.h"
51 #include "ioat_hw.h"
52 #include "ioat_internal.h"
53 
54 #define	IOAT_INTR_TIMO	(hz / 10)
55 #define	IOAT_REFLK	(&ioat->submit_lock)
56 
57 static int ioat_probe(device_t device);
58 static int ioat_attach(device_t device);
59 static int ioat_detach(device_t device);
60 static int ioat_setup_intr(struct ioat_softc *ioat);
61 static int ioat_teardown_intr(struct ioat_softc *ioat);
62 static int ioat3_attach(device_t device);
63 static int ioat_start_channel(struct ioat_softc *ioat);
64 static int ioat_map_pci_bar(struct ioat_softc *ioat);
65 static void ioat_dmamap_cb(void *arg, bus_dma_segment_t *segs, int nseg,
66     int error);
67 static void ioat_interrupt_handler(void *arg);
68 static boolean_t ioat_model_resets_msix(struct ioat_softc *ioat);
69 static int chanerr_to_errno(uint32_t);
70 static void ioat_process_events(struct ioat_softc *ioat);
71 static inline uint32_t ioat_get_active(struct ioat_softc *ioat);
72 static inline uint32_t ioat_get_ring_space(struct ioat_softc *ioat);
73 static void ioat_free_ring(struct ioat_softc *, uint32_t size,
74     struct ioat_descriptor **);
75 static void ioat_free_ring_entry(struct ioat_softc *ioat,
76     struct ioat_descriptor *desc);
77 static struct ioat_descriptor *ioat_alloc_ring_entry(struct ioat_softc *,
78     int mflags);
79 static int ioat_reserve_space(struct ioat_softc *, uint32_t, int mflags);
80 static struct ioat_descriptor *ioat_get_ring_entry(struct ioat_softc *ioat,
81     uint32_t index);
82 static struct ioat_descriptor **ioat_prealloc_ring(struct ioat_softc *,
83     uint32_t size, boolean_t need_dscr, int mflags);
84 static int ring_grow(struct ioat_softc *, uint32_t oldorder,
85     struct ioat_descriptor **);
86 static int ring_shrink(struct ioat_softc *, uint32_t oldorder,
87     struct ioat_descriptor **);
88 static void ioat_halted_debug(struct ioat_softc *, uint32_t);
89 static void ioat_timer_callback(void *arg);
90 static void dump_descriptor(void *hw_desc);
91 static void ioat_submit_single(struct ioat_softc *ioat);
92 static void ioat_comp_update_map(void *arg, bus_dma_segment_t *seg, int nseg,
93     int error);
94 static int ioat_reset_hw(struct ioat_softc *ioat);
95 static void ioat_setup_sysctl(device_t device);
96 static int sysctl_handle_reset(SYSCTL_HANDLER_ARGS);
97 static inline struct ioat_softc *ioat_get(struct ioat_softc *,
98     enum ioat_ref_kind);
99 static inline void ioat_put(struct ioat_softc *, enum ioat_ref_kind);
100 static inline void _ioat_putn(struct ioat_softc *, uint32_t,
101     enum ioat_ref_kind, boolean_t);
102 static inline void ioat_putn(struct ioat_softc *, uint32_t,
103     enum ioat_ref_kind);
104 static inline void ioat_putn_locked(struct ioat_softc *, uint32_t,
105     enum ioat_ref_kind);
106 static void ioat_drain_locked(struct ioat_softc *);
107 
108 #define	ioat_log_message(v, ...) do {					\
109 	if ((v) <= g_ioat_debug_level) {				\
110 		device_printf(ioat->device, __VA_ARGS__);		\
111 	}								\
112 } while (0)
113 
114 MALLOC_DEFINE(M_IOAT, "ioat", "ioat driver memory allocations");
115 SYSCTL_NODE(_hw, OID_AUTO, ioat, CTLFLAG_RD, 0, "ioat node");
116 
117 static int g_force_legacy_interrupts;
118 SYSCTL_INT(_hw_ioat, OID_AUTO, force_legacy_interrupts, CTLFLAG_RDTUN,
119     &g_force_legacy_interrupts, 0, "Set to non-zero to force MSI-X disabled");
120 
121 int g_ioat_debug_level = 0;
122 SYSCTL_INT(_hw_ioat, OID_AUTO, debug_level, CTLFLAG_RWTUN, &g_ioat_debug_level,
123     0, "Set log level (0-3) for ioat(4). Higher is more verbose.");
124 
125 /*
126  * OS <-> Driver interface structures
127  */
128 static device_method_t ioat_pci_methods[] = {
129 	/* Device interface */
130 	DEVMETHOD(device_probe,     ioat_probe),
131 	DEVMETHOD(device_attach,    ioat_attach),
132 	DEVMETHOD(device_detach,    ioat_detach),
133 	{ 0, 0 }
134 };
135 
136 static driver_t ioat_pci_driver = {
137 	"ioat",
138 	ioat_pci_methods,
139 	sizeof(struct ioat_softc),
140 };
141 
142 static devclass_t ioat_devclass;
143 DRIVER_MODULE(ioat, pci, ioat_pci_driver, ioat_devclass, 0, 0);
144 MODULE_VERSION(ioat, 1);
145 
146 /*
147  * Private data structures
148  */
149 static struct ioat_softc *ioat_channel[IOAT_MAX_CHANNELS];
150 static int ioat_channel_index = 0;
151 SYSCTL_INT(_hw_ioat, OID_AUTO, channels, CTLFLAG_RD, &ioat_channel_index, 0,
152     "Number of IOAT channels attached");
153 
154 static struct _pcsid
155 {
156 	u_int32_t   type;
157 	const char  *desc;
158 } pci_ids[] = {
159 	{ 0x34308086, "TBG IOAT Ch0" },
160 	{ 0x34318086, "TBG IOAT Ch1" },
161 	{ 0x34328086, "TBG IOAT Ch2" },
162 	{ 0x34338086, "TBG IOAT Ch3" },
163 	{ 0x34298086, "TBG IOAT Ch4" },
164 	{ 0x342a8086, "TBG IOAT Ch5" },
165 	{ 0x342b8086, "TBG IOAT Ch6" },
166 	{ 0x342c8086, "TBG IOAT Ch7" },
167 
168 	{ 0x37108086, "JSF IOAT Ch0" },
169 	{ 0x37118086, "JSF IOAT Ch1" },
170 	{ 0x37128086, "JSF IOAT Ch2" },
171 	{ 0x37138086, "JSF IOAT Ch3" },
172 	{ 0x37148086, "JSF IOAT Ch4" },
173 	{ 0x37158086, "JSF IOAT Ch5" },
174 	{ 0x37168086, "JSF IOAT Ch6" },
175 	{ 0x37178086, "JSF IOAT Ch7" },
176 	{ 0x37188086, "JSF IOAT Ch0 (RAID)" },
177 	{ 0x37198086, "JSF IOAT Ch1 (RAID)" },
178 
179 	{ 0x3c208086, "SNB IOAT Ch0" },
180 	{ 0x3c218086, "SNB IOAT Ch1" },
181 	{ 0x3c228086, "SNB IOAT Ch2" },
182 	{ 0x3c238086, "SNB IOAT Ch3" },
183 	{ 0x3c248086, "SNB IOAT Ch4" },
184 	{ 0x3c258086, "SNB IOAT Ch5" },
185 	{ 0x3c268086, "SNB IOAT Ch6" },
186 	{ 0x3c278086, "SNB IOAT Ch7" },
187 	{ 0x3c2e8086, "SNB IOAT Ch0 (RAID)" },
188 	{ 0x3c2f8086, "SNB IOAT Ch1 (RAID)" },
189 
190 	{ 0x0e208086, "IVB IOAT Ch0" },
191 	{ 0x0e218086, "IVB IOAT Ch1" },
192 	{ 0x0e228086, "IVB IOAT Ch2" },
193 	{ 0x0e238086, "IVB IOAT Ch3" },
194 	{ 0x0e248086, "IVB IOAT Ch4" },
195 	{ 0x0e258086, "IVB IOAT Ch5" },
196 	{ 0x0e268086, "IVB IOAT Ch6" },
197 	{ 0x0e278086, "IVB IOAT Ch7" },
198 	{ 0x0e2e8086, "IVB IOAT Ch0 (RAID)" },
199 	{ 0x0e2f8086, "IVB IOAT Ch1 (RAID)" },
200 
201 	{ 0x2f208086, "HSW IOAT Ch0" },
202 	{ 0x2f218086, "HSW IOAT Ch1" },
203 	{ 0x2f228086, "HSW IOAT Ch2" },
204 	{ 0x2f238086, "HSW IOAT Ch3" },
205 	{ 0x2f248086, "HSW IOAT Ch4" },
206 	{ 0x2f258086, "HSW IOAT Ch5" },
207 	{ 0x2f268086, "HSW IOAT Ch6" },
208 	{ 0x2f278086, "HSW IOAT Ch7" },
209 	{ 0x2f2e8086, "HSW IOAT Ch0 (RAID)" },
210 	{ 0x2f2f8086, "HSW IOAT Ch1 (RAID)" },
211 
212 	{ 0x0c508086, "BWD IOAT Ch0" },
213 	{ 0x0c518086, "BWD IOAT Ch1" },
214 	{ 0x0c528086, "BWD IOAT Ch2" },
215 	{ 0x0c538086, "BWD IOAT Ch3" },
216 
217 	{ 0x6f508086, "BDXDE IOAT Ch0" },
218 	{ 0x6f518086, "BDXDE IOAT Ch1" },
219 	{ 0x6f528086, "BDXDE IOAT Ch2" },
220 	{ 0x6f538086, "BDXDE IOAT Ch3" },
221 
222 	{ 0x6f208086, "BDX IOAT Ch0" },
223 	{ 0x6f218086, "BDX IOAT Ch1" },
224 	{ 0x6f228086, "BDX IOAT Ch2" },
225 	{ 0x6f238086, "BDX IOAT Ch3" },
226 	{ 0x6f248086, "BDX IOAT Ch4" },
227 	{ 0x6f258086, "BDX IOAT Ch5" },
228 	{ 0x6f268086, "BDX IOAT Ch6" },
229 	{ 0x6f278086, "BDX IOAT Ch7" },
230 	{ 0x6f2e8086, "BDX IOAT Ch0 (RAID)" },
231 	{ 0x6f2f8086, "BDX IOAT Ch1 (RAID)" },
232 
233 	{ 0x00000000, NULL           }
234 };
235 
236 /*
237  * OS <-> Driver linkage functions
238  */
239 static int
240 ioat_probe(device_t device)
241 {
242 	struct _pcsid *ep;
243 	u_int32_t type;
244 
245 	type = pci_get_devid(device);
246 	for (ep = pci_ids; ep->type; ep++) {
247 		if (ep->type == type) {
248 			device_set_desc(device, ep->desc);
249 			return (0);
250 		}
251 	}
252 	return (ENXIO);
253 }
254 
255 static int
256 ioat_attach(device_t device)
257 {
258 	struct ioat_softc *ioat;
259 	int error;
260 
261 	ioat = DEVICE2SOFTC(device);
262 	ioat->device = device;
263 
264 	error = ioat_map_pci_bar(ioat);
265 	if (error != 0)
266 		goto err;
267 
268 	ioat->version = ioat_read_cbver(ioat);
269 	if (ioat->version < IOAT_VER_3_0) {
270 		error = ENODEV;
271 		goto err;
272 	}
273 
274 	error = ioat3_attach(device);
275 	if (error != 0)
276 		goto err;
277 
278 	error = pci_enable_busmaster(device);
279 	if (error != 0)
280 		goto err;
281 
282 	error = ioat_setup_intr(ioat);
283 	if (error != 0)
284 		goto err;
285 
286 	error = ioat_reset_hw(ioat);
287 	if (error != 0)
288 		goto err;
289 
290 	ioat_process_events(ioat);
291 	ioat_setup_sysctl(device);
292 
293 	ioat->chan_idx = ioat_channel_index;
294 	ioat_channel[ioat_channel_index++] = ioat;
295 	ioat_test_attach();
296 
297 err:
298 	if (error != 0)
299 		ioat_detach(device);
300 	return (error);
301 }
302 
303 static int
304 ioat_detach(device_t device)
305 {
306 	struct ioat_softc *ioat;
307 
308 	ioat = DEVICE2SOFTC(device);
309 
310 	ioat_test_detach();
311 
312 	mtx_lock(IOAT_REFLK);
313 	ioat->quiescing = TRUE;
314 	ioat_channel[ioat->chan_idx] = NULL;
315 
316 	ioat_drain_locked(ioat);
317 	mtx_unlock(IOAT_REFLK);
318 
319 	ioat_teardown_intr(ioat);
320 	callout_drain(&ioat->timer);
321 
322 	pci_disable_busmaster(device);
323 
324 	if (ioat->pci_resource != NULL)
325 		bus_release_resource(device, SYS_RES_MEMORY,
326 		    ioat->pci_resource_id, ioat->pci_resource);
327 
328 	if (ioat->ring != NULL)
329 		ioat_free_ring(ioat, 1 << ioat->ring_size_order, ioat->ring);
330 
331 	if (ioat->comp_update != NULL) {
332 		bus_dmamap_unload(ioat->comp_update_tag, ioat->comp_update_map);
333 		bus_dmamem_free(ioat->comp_update_tag, ioat->comp_update,
334 		    ioat->comp_update_map);
335 		bus_dma_tag_destroy(ioat->comp_update_tag);
336 	}
337 
338 	bus_dma_tag_destroy(ioat->hw_desc_tag);
339 
340 	return (0);
341 }
342 
343 static int
344 ioat_teardown_intr(struct ioat_softc *ioat)
345 {
346 
347 	if (ioat->tag != NULL)
348 		bus_teardown_intr(ioat->device, ioat->res, ioat->tag);
349 
350 	if (ioat->res != NULL)
351 		bus_release_resource(ioat->device, SYS_RES_IRQ,
352 		    rman_get_rid(ioat->res), ioat->res);
353 
354 	pci_release_msi(ioat->device);
355 	return (0);
356 }
357 
358 static int
359 ioat_start_channel(struct ioat_softc *ioat)
360 {
361 	uint64_t status;
362 	uint32_t chanerr;
363 	int i;
364 
365 	ioat_acquire(&ioat->dmaengine);
366 	ioat_null(&ioat->dmaengine, NULL, NULL, 0);
367 	ioat_release(&ioat->dmaengine);
368 
369 	for (i = 0; i < 100; i++) {
370 		DELAY(1);
371 		status = ioat_get_chansts(ioat);
372 		if (is_ioat_idle(status))
373 			return (0);
374 	}
375 
376 	chanerr = ioat_read_4(ioat, IOAT_CHANERR_OFFSET);
377 	ioat_log_message(0, "could not start channel: "
378 	    "status = %#jx error = %b\n", (uintmax_t)status, (int)chanerr,
379 	    IOAT_CHANERR_STR);
380 	return (ENXIO);
381 }
382 
383 /*
384  * Initialize Hardware
385  */
386 static int
387 ioat3_attach(device_t device)
388 {
389 	struct ioat_softc *ioat;
390 	struct ioat_descriptor **ring;
391 	struct ioat_descriptor *next;
392 	struct ioat_dma_hw_descriptor *dma_hw_desc;
393 	int i, num_descriptors;
394 	int error;
395 	uint8_t xfercap;
396 
397 	error = 0;
398 	ioat = DEVICE2SOFTC(device);
399 	ioat->capabilities = ioat_read_dmacapability(ioat);
400 
401 	ioat_log_message(1, "Capabilities: %b\n", (int)ioat->capabilities,
402 	    IOAT_DMACAP_STR);
403 
404 	xfercap = ioat_read_xfercap(ioat);
405 	ioat->max_xfer_size = 1 << xfercap;
406 
407 	ioat->intrdelay_supported = (ioat_read_2(ioat, IOAT_INTRDELAY_OFFSET) &
408 	    IOAT_INTRDELAY_SUPPORTED) != 0;
409 	if (ioat->intrdelay_supported)
410 		ioat->intrdelay_max = IOAT_INTRDELAY_US_MASK;
411 
412 	/* TODO: need to check DCA here if we ever do XOR/PQ */
413 
414 	mtx_init(&ioat->submit_lock, "ioat_submit", NULL, MTX_DEF);
415 	mtx_init(&ioat->cleanup_lock, "ioat_cleanup", NULL, MTX_DEF);
416 	callout_init(&ioat->timer, 1);
417 
418 	/* Establish lock order for Witness */
419 	mtx_lock(&ioat->submit_lock);
420 	mtx_lock(&ioat->cleanup_lock);
421 	mtx_unlock(&ioat->cleanup_lock);
422 	mtx_unlock(&ioat->submit_lock);
423 
424 	ioat->is_resize_pending = FALSE;
425 	ioat->is_completion_pending = FALSE;
426 	ioat->is_reset_pending = FALSE;
427 	ioat->is_channel_running = FALSE;
428 
429 	bus_dma_tag_create(bus_get_dma_tag(ioat->device), sizeof(uint64_t), 0x0,
430 	    BUS_SPACE_MAXADDR, BUS_SPACE_MAXADDR, NULL, NULL,
431 	    sizeof(uint64_t), 1, sizeof(uint64_t), 0, NULL, NULL,
432 	    &ioat->comp_update_tag);
433 
434 	error = bus_dmamem_alloc(ioat->comp_update_tag,
435 	    (void **)&ioat->comp_update, BUS_DMA_ZERO, &ioat->comp_update_map);
436 	if (ioat->comp_update == NULL)
437 		return (ENOMEM);
438 
439 	error = bus_dmamap_load(ioat->comp_update_tag, ioat->comp_update_map,
440 	    ioat->comp_update, sizeof(uint64_t), ioat_comp_update_map, ioat,
441 	    0);
442 	if (error != 0)
443 		return (error);
444 
445 	ioat->ring_size_order = IOAT_MIN_ORDER;
446 
447 	num_descriptors = 1 << ioat->ring_size_order;
448 
449 	bus_dma_tag_create(bus_get_dma_tag(ioat->device), 0x40, 0x0,
450 	    BUS_SPACE_MAXADDR, BUS_SPACE_MAXADDR, NULL, NULL,
451 	    sizeof(struct ioat_dma_hw_descriptor), 1,
452 	    sizeof(struct ioat_dma_hw_descriptor), 0, NULL, NULL,
453 	    &ioat->hw_desc_tag);
454 
455 	ioat->ring = malloc(num_descriptors * sizeof(*ring), M_IOAT,
456 	    M_ZERO | M_WAITOK);
457 	if (ioat->ring == NULL)
458 		return (ENOMEM);
459 
460 	ring = ioat->ring;
461 	for (i = 0; i < num_descriptors; i++) {
462 		ring[i] = ioat_alloc_ring_entry(ioat, M_WAITOK);
463 		if (ring[i] == NULL)
464 			return (ENOMEM);
465 
466 		ring[i]->id = i;
467 	}
468 
469 	for (i = 0; i < num_descriptors - 1; i++) {
470 		next = ring[i + 1];
471 		dma_hw_desc = ring[i]->u.dma;
472 
473 		dma_hw_desc->next = next->hw_desc_bus_addr;
474 	}
475 
476 	ring[i]->u.dma->next = ring[0]->hw_desc_bus_addr;
477 
478 	ioat->head = ioat->hw_head = 0;
479 	ioat->tail = 0;
480 	ioat->last_seen = 0;
481 	return (0);
482 }
483 
484 static int
485 ioat_map_pci_bar(struct ioat_softc *ioat)
486 {
487 
488 	ioat->pci_resource_id = PCIR_BAR(0);
489 	ioat->pci_resource = bus_alloc_resource_any(ioat->device,
490 	    SYS_RES_MEMORY, &ioat->pci_resource_id, RF_ACTIVE);
491 
492 	if (ioat->pci_resource == NULL) {
493 		ioat_log_message(0, "unable to allocate pci resource\n");
494 		return (ENODEV);
495 	}
496 
497 	ioat->pci_bus_tag = rman_get_bustag(ioat->pci_resource);
498 	ioat->pci_bus_handle = rman_get_bushandle(ioat->pci_resource);
499 	return (0);
500 }
501 
502 static void
503 ioat_comp_update_map(void *arg, bus_dma_segment_t *seg, int nseg, int error)
504 {
505 	struct ioat_softc *ioat = arg;
506 
507 	KASSERT(error == 0, ("%s: error:%d", __func__, error));
508 	ioat->comp_update_bus_addr = seg[0].ds_addr;
509 }
510 
511 static void
512 ioat_dmamap_cb(void *arg, bus_dma_segment_t *segs, int nseg, int error)
513 {
514 	bus_addr_t *baddr;
515 
516 	KASSERT(error == 0, ("%s: error:%d", __func__, error));
517 	baddr = arg;
518 	*baddr = segs->ds_addr;
519 }
520 
521 /*
522  * Interrupt setup and handlers
523  */
524 static int
525 ioat_setup_intr(struct ioat_softc *ioat)
526 {
527 	uint32_t num_vectors;
528 	int error;
529 	boolean_t use_msix;
530 	boolean_t force_legacy_interrupts;
531 
532 	use_msix = FALSE;
533 	force_legacy_interrupts = FALSE;
534 
535 	if (!g_force_legacy_interrupts && pci_msix_count(ioat->device) >= 1) {
536 		num_vectors = 1;
537 		pci_alloc_msix(ioat->device, &num_vectors);
538 		if (num_vectors == 1)
539 			use_msix = TRUE;
540 	}
541 
542 	if (use_msix) {
543 		ioat->rid = 1;
544 		ioat->res = bus_alloc_resource_any(ioat->device, SYS_RES_IRQ,
545 		    &ioat->rid, RF_ACTIVE);
546 	} else {
547 		ioat->rid = 0;
548 		ioat->res = bus_alloc_resource_any(ioat->device, SYS_RES_IRQ,
549 		    &ioat->rid, RF_SHAREABLE | RF_ACTIVE);
550 	}
551 	if (ioat->res == NULL) {
552 		ioat_log_message(0, "bus_alloc_resource failed\n");
553 		return (ENOMEM);
554 	}
555 
556 	ioat->tag = NULL;
557 	error = bus_setup_intr(ioat->device, ioat->res, INTR_MPSAFE |
558 	    INTR_TYPE_MISC, NULL, ioat_interrupt_handler, ioat, &ioat->tag);
559 	if (error != 0) {
560 		ioat_log_message(0, "bus_setup_intr failed\n");
561 		return (error);
562 	}
563 
564 	ioat_write_intrctrl(ioat, IOAT_INTRCTRL_MASTER_INT_EN);
565 	return (0);
566 }
567 
568 static boolean_t
569 ioat_model_resets_msix(struct ioat_softc *ioat)
570 {
571 	u_int32_t pciid;
572 
573 	pciid = pci_get_devid(ioat->device);
574 	switch (pciid) {
575 		/* BWD: */
576 	case 0x0c508086:
577 	case 0x0c518086:
578 	case 0x0c528086:
579 	case 0x0c538086:
580 		/* BDXDE: */
581 	case 0x6f508086:
582 	case 0x6f518086:
583 	case 0x6f528086:
584 	case 0x6f538086:
585 		return (TRUE);
586 	}
587 
588 	return (FALSE);
589 }
590 
591 static void
592 ioat_interrupt_handler(void *arg)
593 {
594 	struct ioat_softc *ioat = arg;
595 
596 	ioat->stats.interrupts++;
597 	ioat_process_events(ioat);
598 }
599 
600 static int
601 chanerr_to_errno(uint32_t chanerr)
602 {
603 
604 	if (chanerr == 0)
605 		return (0);
606 	if ((chanerr & (IOAT_CHANERR_XSADDERR | IOAT_CHANERR_XDADDERR)) != 0)
607 		return (EFAULT);
608 	if ((chanerr & (IOAT_CHANERR_RDERR | IOAT_CHANERR_WDERR)) != 0)
609 		return (EIO);
610 	/* This one is probably our fault: */
611 	if ((chanerr & IOAT_CHANERR_NDADDERR) != 0)
612 		return (EIO);
613 	return (EIO);
614 }
615 
616 static void
617 ioat_process_events(struct ioat_softc *ioat)
618 {
619 	struct ioat_descriptor *desc;
620 	struct bus_dmadesc *dmadesc;
621 	uint64_t comp_update, status;
622 	uint32_t completed, chanerr;
623 	int error;
624 
625 	mtx_lock(&ioat->cleanup_lock);
626 
627 	completed = 0;
628 	comp_update = *ioat->comp_update;
629 	status = comp_update & IOAT_CHANSTS_COMPLETED_DESCRIPTOR_MASK;
630 
631 	CTR0(KTR_IOAT, __func__);
632 
633 	if (status == ioat->last_seen)
634 		goto out;
635 
636 	while (1) {
637 		desc = ioat_get_ring_entry(ioat, ioat->tail);
638 		dmadesc = &desc->bus_dmadesc;
639 		CTR1(KTR_IOAT, "completing desc %d", ioat->tail);
640 
641 		if (dmadesc->callback_fn != NULL)
642 			dmadesc->callback_fn(dmadesc->callback_arg, 0);
643 
644 		completed++;
645 		ioat->tail++;
646 		if (desc->hw_desc_bus_addr == status)
647 			break;
648 	}
649 
650 	ioat->last_seen = desc->hw_desc_bus_addr;
651 
652 	if (ioat->head == ioat->tail) {
653 		ioat->is_completion_pending = FALSE;
654 		callout_reset(&ioat->timer, IOAT_INTR_TIMO,
655 		    ioat_timer_callback, ioat);
656 	}
657 
658 	ioat->stats.descriptors_processed += completed;
659 
660 out:
661 	ioat_write_chanctrl(ioat, IOAT_CHANCTRL_RUN);
662 	mtx_unlock(&ioat->cleanup_lock);
663 
664 	ioat_putn(ioat, completed, IOAT_ACTIVE_DESCR_REF);
665 	wakeup(&ioat->tail);
666 
667 	if (!is_ioat_halted(comp_update))
668 		return;
669 
670 	ioat->stats.channel_halts++;
671 
672 	/*
673 	 * Fatal programming error on this DMA channel.  Flush any outstanding
674 	 * work with error status and restart the engine.
675 	 */
676 	ioat_log_message(0, "Channel halted due to fatal programming error\n");
677 	mtx_lock(&ioat->submit_lock);
678 	mtx_lock(&ioat->cleanup_lock);
679 	ioat->quiescing = TRUE;
680 
681 	chanerr = ioat_read_4(ioat, IOAT_CHANERR_OFFSET);
682 	ioat_halted_debug(ioat, chanerr);
683 	ioat->stats.last_halt_chanerr = chanerr;
684 
685 	while (ioat_get_active(ioat) > 0) {
686 		desc = ioat_get_ring_entry(ioat, ioat->tail);
687 		dmadesc = &desc->bus_dmadesc;
688 		CTR1(KTR_IOAT, "completing err desc %d", ioat->tail);
689 
690 		if (dmadesc->callback_fn != NULL)
691 			dmadesc->callback_fn(dmadesc->callback_arg,
692 			    chanerr_to_errno(chanerr));
693 
694 		ioat_putn_locked(ioat, 1, IOAT_ACTIVE_DESCR_REF);
695 		ioat->tail++;
696 		ioat->stats.descriptors_processed++;
697 		ioat->stats.descriptors_error++;
698 	}
699 
700 	/* Clear error status */
701 	ioat_write_4(ioat, IOAT_CHANERR_OFFSET, chanerr);
702 
703 	mtx_unlock(&ioat->cleanup_lock);
704 	mtx_unlock(&ioat->submit_lock);
705 
706 	ioat_log_message(0, "Resetting channel to recover from error\n");
707 	error = ioat_reset_hw(ioat);
708 	KASSERT(error == 0, ("%s: reset failed: %d", __func__, error));
709 }
710 
711 /*
712  * User API functions
713  */
714 bus_dmaengine_t
715 ioat_get_dmaengine(uint32_t index)
716 {
717 	struct ioat_softc *sc;
718 
719 	if (index >= ioat_channel_index)
720 		return (NULL);
721 
722 	sc = ioat_channel[index];
723 	if (sc == NULL || sc->quiescing)
724 		return (NULL);
725 
726 	return (&ioat_get(sc, IOAT_DMAENGINE_REF)->dmaengine);
727 }
728 
729 void
730 ioat_put_dmaengine(bus_dmaengine_t dmaengine)
731 {
732 	struct ioat_softc *ioat;
733 
734 	ioat = to_ioat_softc(dmaengine);
735 	ioat_put(ioat, IOAT_DMAENGINE_REF);
736 }
737 
738 int
739 ioat_set_interrupt_coalesce(bus_dmaengine_t dmaengine, uint16_t delay)
740 {
741 	struct ioat_softc *ioat;
742 
743 	ioat = to_ioat_softc(dmaengine);
744 	if (!ioat->intrdelay_supported)
745 		return (ENODEV);
746 	if (delay > ioat->intrdelay_max)
747 		return (ERANGE);
748 
749 	ioat_write_2(ioat, IOAT_INTRDELAY_OFFSET, delay);
750 	ioat->cached_intrdelay =
751 	    ioat_read_2(ioat, IOAT_INTRDELAY_OFFSET) & IOAT_INTRDELAY_US_MASK;
752 	return (0);
753 }
754 
755 uint16_t
756 ioat_get_max_coalesce_period(bus_dmaengine_t dmaengine)
757 {
758 	struct ioat_softc *ioat;
759 
760 	ioat = to_ioat_softc(dmaengine);
761 	return (ioat->intrdelay_max);
762 }
763 
764 void
765 ioat_acquire(bus_dmaengine_t dmaengine)
766 {
767 	struct ioat_softc *ioat;
768 
769 	ioat = to_ioat_softc(dmaengine);
770 	mtx_lock(&ioat->submit_lock);
771 	CTR0(KTR_IOAT, __func__);
772 }
773 
774 void
775 ioat_release(bus_dmaengine_t dmaengine)
776 {
777 	struct ioat_softc *ioat;
778 
779 	ioat = to_ioat_softc(dmaengine);
780 	CTR0(KTR_IOAT, __func__);
781 	ioat_write_2(ioat, IOAT_DMACOUNT_OFFSET, (uint16_t)ioat->hw_head);
782 	mtx_unlock(&ioat->submit_lock);
783 }
784 
785 static struct ioat_descriptor *
786 ioat_op_generic(struct ioat_softc *ioat, uint8_t op,
787     uint32_t size, uint64_t src, uint64_t dst,
788     bus_dmaengine_callback_t callback_fn, void *callback_arg,
789     uint32_t flags)
790 {
791 	struct ioat_generic_hw_descriptor *hw_desc;
792 	struct ioat_descriptor *desc;
793 	int mflags;
794 
795 	mtx_assert(&ioat->submit_lock, MA_OWNED);
796 
797 	KASSERT((flags & ~DMA_ALL_FLAGS) == 0, ("Unrecognized flag(s): %#x",
798 		flags & ~DMA_ALL_FLAGS));
799 	if ((flags & DMA_NO_WAIT) != 0)
800 		mflags = M_NOWAIT;
801 	else
802 		mflags = M_WAITOK;
803 
804 	if (size > ioat->max_xfer_size) {
805 		ioat_log_message(0, "%s: max_xfer_size = %d, requested = %u\n",
806 		    __func__, ioat->max_xfer_size, (unsigned)size);
807 		return (NULL);
808 	}
809 
810 	if (ioat_reserve_space(ioat, 1, mflags) != 0)
811 		return (NULL);
812 
813 	desc = ioat_get_ring_entry(ioat, ioat->head);
814 	hw_desc = desc->u.generic;
815 
816 	hw_desc->u.control_raw = 0;
817 	hw_desc->u.control_generic.op = op;
818 	hw_desc->u.control_generic.completion_update = 1;
819 
820 	if ((flags & DMA_INT_EN) != 0)
821 		hw_desc->u.control_generic.int_enable = 1;
822 
823 	hw_desc->size = size;
824 	hw_desc->src_addr = src;
825 	hw_desc->dest_addr = dst;
826 
827 	desc->bus_dmadesc.callback_fn = callback_fn;
828 	desc->bus_dmadesc.callback_arg = callback_arg;
829 	return (desc);
830 }
831 
832 struct bus_dmadesc *
833 ioat_null(bus_dmaengine_t dmaengine, bus_dmaengine_callback_t callback_fn,
834     void *callback_arg, uint32_t flags)
835 {
836 	struct ioat_dma_hw_descriptor *hw_desc;
837 	struct ioat_descriptor *desc;
838 	struct ioat_softc *ioat;
839 
840 	CTR0(KTR_IOAT, __func__);
841 	ioat = to_ioat_softc(dmaengine);
842 
843 	desc = ioat_op_generic(ioat, IOAT_OP_COPY, 8, 0, 0, callback_fn,
844 	    callback_arg, flags);
845 	if (desc == NULL)
846 		return (NULL);
847 
848 	hw_desc = desc->u.dma;
849 	hw_desc->u.control.null = 1;
850 	ioat_submit_single(ioat);
851 	return (&desc->bus_dmadesc);
852 }
853 
854 struct bus_dmadesc *
855 ioat_copy(bus_dmaengine_t dmaengine, bus_addr_t dst,
856     bus_addr_t src, bus_size_t len, bus_dmaengine_callback_t callback_fn,
857     void *callback_arg, uint32_t flags)
858 {
859 	struct ioat_dma_hw_descriptor *hw_desc;
860 	struct ioat_descriptor *desc;
861 	struct ioat_softc *ioat;
862 
863 	CTR0(KTR_IOAT, __func__);
864 	ioat = to_ioat_softc(dmaengine);
865 
866 	if (((src | dst) & (0xffffull << 48)) != 0) {
867 		ioat_log_message(0, "%s: High 16 bits of src/dst invalid\n",
868 		    __func__);
869 		return (NULL);
870 	}
871 
872 	desc = ioat_op_generic(ioat, IOAT_OP_COPY, len, src, dst, callback_fn,
873 	    callback_arg, flags);
874 	if (desc == NULL)
875 		return (NULL);
876 
877 	hw_desc = desc->u.dma;
878 	if (g_ioat_debug_level >= 3)
879 		dump_descriptor(hw_desc);
880 
881 	ioat_submit_single(ioat);
882 	return (&desc->bus_dmadesc);
883 }
884 
885 struct bus_dmadesc *
886 ioat_copy_8k_aligned(bus_dmaengine_t dmaengine, bus_addr_t dst1,
887     bus_addr_t dst2, bus_addr_t src1, bus_addr_t src2,
888     bus_dmaengine_callback_t callback_fn, void *callback_arg, uint32_t flags)
889 {
890 	struct ioat_dma_hw_descriptor *hw_desc;
891 	struct ioat_descriptor *desc;
892 	struct ioat_softc *ioat;
893 
894 	CTR0(KTR_IOAT, __func__);
895 	ioat = to_ioat_softc(dmaengine);
896 
897 	if (((src1 | src2 | dst1 | dst2) & (0xffffull << 48)) != 0) {
898 		ioat_log_message(0, "%s: High 16 bits of src/dst invalid\n",
899 		    __func__);
900 		return (NULL);
901 	}
902 	if (((src1 | src2 | dst1 | dst2) & PAGE_MASK) != 0) {
903 		ioat_log_message(0, "%s: Addresses must be page-aligned\n",
904 		    __func__);
905 		return (NULL);
906 	}
907 
908 	desc = ioat_op_generic(ioat, IOAT_OP_COPY, 2 * PAGE_SIZE, src1, dst1,
909 	    callback_fn, callback_arg, flags);
910 	if (desc == NULL)
911 		return (NULL);
912 
913 	hw_desc = desc->u.dma;
914 	if (src2 != src1 + PAGE_SIZE) {
915 		hw_desc->u.control.src_page_break = 1;
916 		hw_desc->next_src_addr = src2;
917 	}
918 	if (dst2 != dst1 + PAGE_SIZE) {
919 		hw_desc->u.control.dest_page_break = 1;
920 		hw_desc->next_dest_addr = dst2;
921 	}
922 
923 	if (g_ioat_debug_level >= 3)
924 		dump_descriptor(hw_desc);
925 
926 	ioat_submit_single(ioat);
927 	return (&desc->bus_dmadesc);
928 }
929 
930 struct bus_dmadesc *
931 ioat_blockfill(bus_dmaengine_t dmaengine, bus_addr_t dst, uint64_t fillpattern,
932     bus_size_t len, bus_dmaengine_callback_t callback_fn, void *callback_arg,
933     uint32_t flags)
934 {
935 	struct ioat_fill_hw_descriptor *hw_desc;
936 	struct ioat_descriptor *desc;
937 	struct ioat_softc *ioat;
938 
939 	CTR0(KTR_IOAT, __func__);
940 	ioat = to_ioat_softc(dmaengine);
941 
942 	if ((ioat->capabilities & IOAT_DMACAP_BFILL) == 0) {
943 		ioat_log_message(0, "%s: Device lacks BFILL capability\n",
944 		    __func__);
945 		return (NULL);
946 	}
947 
948 	if ((dst & (0xffffull << 48)) != 0) {
949 		ioat_log_message(0, "%s: High 16 bits of dst invalid\n",
950 		    __func__);
951 		return (NULL);
952 	}
953 
954 	desc = ioat_op_generic(ioat, IOAT_OP_FILL, len, fillpattern, dst,
955 	    callback_fn, callback_arg, flags);
956 	if (desc == NULL)
957 		return (NULL);
958 
959 	hw_desc = desc->u.fill;
960 	if (g_ioat_debug_level >= 3)
961 		dump_descriptor(hw_desc);
962 
963 	ioat_submit_single(ioat);
964 	return (&desc->bus_dmadesc);
965 }
966 
967 /*
968  * Ring Management
969  */
970 static inline uint32_t
971 ioat_get_active(struct ioat_softc *ioat)
972 {
973 
974 	return ((ioat->head - ioat->tail) & ((1 << ioat->ring_size_order) - 1));
975 }
976 
977 static inline uint32_t
978 ioat_get_ring_space(struct ioat_softc *ioat)
979 {
980 
981 	return ((1 << ioat->ring_size_order) - ioat_get_active(ioat) - 1);
982 }
983 
984 static struct ioat_descriptor *
985 ioat_alloc_ring_entry(struct ioat_softc *ioat, int mflags)
986 {
987 	struct ioat_generic_hw_descriptor *hw_desc;
988 	struct ioat_descriptor *desc;
989 	int error, busdmaflag;
990 
991 	error = ENOMEM;
992 	hw_desc = NULL;
993 
994 	if ((mflags & M_WAITOK) != 0)
995 		busdmaflag = BUS_DMA_WAITOK;
996 	else
997 		busdmaflag = BUS_DMA_NOWAIT;
998 
999 	desc = malloc(sizeof(*desc), M_IOAT, mflags);
1000 	if (desc == NULL)
1001 		goto out;
1002 
1003 	bus_dmamem_alloc(ioat->hw_desc_tag, (void **)&hw_desc,
1004 	    BUS_DMA_ZERO | busdmaflag, &ioat->hw_desc_map);
1005 	if (hw_desc == NULL)
1006 		goto out;
1007 
1008 	memset(&desc->bus_dmadesc, 0, sizeof(desc->bus_dmadesc));
1009 	desc->u.generic = hw_desc;
1010 
1011 	error = bus_dmamap_load(ioat->hw_desc_tag, ioat->hw_desc_map, hw_desc,
1012 	    sizeof(*hw_desc), ioat_dmamap_cb, &desc->hw_desc_bus_addr,
1013 	    busdmaflag);
1014 	if (error)
1015 		goto out;
1016 
1017 out:
1018 	if (error) {
1019 		ioat_free_ring_entry(ioat, desc);
1020 		return (NULL);
1021 	}
1022 	return (desc);
1023 }
1024 
1025 static void
1026 ioat_free_ring_entry(struct ioat_softc *ioat, struct ioat_descriptor *desc)
1027 {
1028 
1029 	if (desc == NULL)
1030 		return;
1031 
1032 	if (desc->u.generic)
1033 		bus_dmamem_free(ioat->hw_desc_tag, desc->u.generic,
1034 		    ioat->hw_desc_map);
1035 	free(desc, M_IOAT);
1036 }
1037 
1038 /*
1039  * Reserves space in this IOAT descriptor ring by ensuring enough slots remain
1040  * for 'num_descs'.
1041  *
1042  * If mflags contains M_WAITOK, blocks until enough space is available.
1043  *
1044  * Returns zero on success, or an errno on error.  If num_descs is beyond the
1045  * maximum ring size, returns EINVAl; if allocation would block and mflags
1046  * contains M_NOWAIT, returns EAGAIN.
1047  *
1048  * Must be called with the submit_lock held; returns with the lock held.  The
1049  * lock may be dropped to allocate the ring.
1050  *
1051  * (The submit_lock is needed to add any entries to the ring, so callers are
1052  * assured enough room is available.)
1053  */
1054 static int
1055 ioat_reserve_space(struct ioat_softc *ioat, uint32_t num_descs, int mflags)
1056 {
1057 	struct ioat_descriptor **new_ring;
1058 	uint32_t order;
1059 	int error;
1060 
1061 	mtx_assert(&ioat->submit_lock, MA_OWNED);
1062 	error = 0;
1063 
1064 	if (num_descs < 1 || num_descs > (1 << IOAT_MAX_ORDER)) {
1065 		error = EINVAL;
1066 		goto out;
1067 	}
1068 	if (ioat->quiescing) {
1069 		error = ENXIO;
1070 		goto out;
1071 	}
1072 
1073 	for (;;) {
1074 		if (ioat_get_ring_space(ioat) >= num_descs)
1075 			goto out;
1076 
1077 		order = ioat->ring_size_order;
1078 		if (ioat->is_resize_pending || order == IOAT_MAX_ORDER) {
1079 			if ((mflags & M_WAITOK) != 0) {
1080 				msleep(&ioat->tail, &ioat->submit_lock, 0,
1081 				    "ioat_rsz", 0);
1082 				continue;
1083 			}
1084 
1085 			error = EAGAIN;
1086 			break;
1087 		}
1088 
1089 		ioat->is_resize_pending = TRUE;
1090 		for (;;) {
1091 			mtx_unlock(&ioat->submit_lock);
1092 
1093 			new_ring = ioat_prealloc_ring(ioat, 1 << (order + 1),
1094 			    TRUE, mflags);
1095 
1096 			mtx_lock(&ioat->submit_lock);
1097 			KASSERT(ioat->ring_size_order == order,
1098 			    ("is_resize_pending should protect order"));
1099 
1100 			if (new_ring == NULL) {
1101 				KASSERT((mflags & M_WAITOK) == 0,
1102 				    ("allocation failed"));
1103 				error = EAGAIN;
1104 				break;
1105 			}
1106 
1107 			error = ring_grow(ioat, order, new_ring);
1108 			if (error == 0)
1109 				break;
1110 		}
1111 		ioat->is_resize_pending = FALSE;
1112 		wakeup(&ioat->tail);
1113 		if (error)
1114 			break;
1115 	}
1116 
1117 out:
1118 	mtx_assert(&ioat->submit_lock, MA_OWNED);
1119 	return (error);
1120 }
1121 
1122 static struct ioat_descriptor **
1123 ioat_prealloc_ring(struct ioat_softc *ioat, uint32_t size, boolean_t need_dscr,
1124     int mflags)
1125 {
1126 	struct ioat_descriptor **ring;
1127 	uint32_t i;
1128 	int error;
1129 
1130 	KASSERT(size > 0 && powerof2(size), ("bogus size"));
1131 
1132 	ring = malloc(size * sizeof(*ring), M_IOAT, M_ZERO | mflags);
1133 	if (ring == NULL)
1134 		return (NULL);
1135 
1136 	if (need_dscr) {
1137 		error = ENOMEM;
1138 		for (i = size / 2; i < size; i++) {
1139 			ring[i] = ioat_alloc_ring_entry(ioat, mflags);
1140 			if (ring[i] == NULL)
1141 				goto out;
1142 			ring[i]->id = i;
1143 		}
1144 	}
1145 	error = 0;
1146 
1147 out:
1148 	if (error != 0 && ring != NULL) {
1149 		ioat_free_ring(ioat, size, ring);
1150 		ring = NULL;
1151 	}
1152 	return (ring);
1153 }
1154 
1155 static void
1156 ioat_free_ring(struct ioat_softc *ioat, uint32_t size,
1157     struct ioat_descriptor **ring)
1158 {
1159 	uint32_t i;
1160 
1161 	for (i = 0; i < size; i++) {
1162 		if (ring[i] != NULL)
1163 			ioat_free_ring_entry(ioat, ring[i]);
1164 	}
1165 	free(ring, M_IOAT);
1166 }
1167 
1168 static struct ioat_descriptor *
1169 ioat_get_ring_entry(struct ioat_softc *ioat, uint32_t index)
1170 {
1171 
1172 	return (ioat->ring[index % (1 << ioat->ring_size_order)]);
1173 }
1174 
1175 static int
1176 ring_grow(struct ioat_softc *ioat, uint32_t oldorder,
1177     struct ioat_descriptor **newring)
1178 {
1179 	struct ioat_descriptor *tmp, *next;
1180 	struct ioat_dma_hw_descriptor *hw;
1181 	uint32_t oldsize, newsize, head, tail, i, end;
1182 	int error;
1183 
1184 	CTR0(KTR_IOAT, __func__);
1185 
1186 	mtx_assert(&ioat->submit_lock, MA_OWNED);
1187 
1188 	if (oldorder != ioat->ring_size_order || oldorder >= IOAT_MAX_ORDER) {
1189 		error = EINVAL;
1190 		goto out;
1191 	}
1192 
1193 	oldsize = (1 << oldorder);
1194 	newsize = (1 << (oldorder + 1));
1195 
1196 	mtx_lock(&ioat->cleanup_lock);
1197 
1198 	head = ioat->head & (oldsize - 1);
1199 	tail = ioat->tail & (oldsize - 1);
1200 
1201 	/* Copy old descriptors to new ring */
1202 	for (i = 0; i < oldsize; i++)
1203 		newring[i] = ioat->ring[i];
1204 
1205 	/*
1206 	 * If head has wrapped but tail hasn't, we must swap some descriptors
1207 	 * around so that tail can increment directly to head.
1208 	 */
1209 	if (head < tail) {
1210 		for (i = 0; i <= head; i++) {
1211 			tmp = newring[oldsize + i];
1212 
1213 			newring[oldsize + i] = newring[i];
1214 			newring[oldsize + i]->id = oldsize + i;
1215 
1216 			newring[i] = tmp;
1217 			newring[i]->id = i;
1218 		}
1219 		head += oldsize;
1220 	}
1221 
1222 	KASSERT(head >= tail, ("invariants"));
1223 
1224 	/* Head didn't wrap; we only need to link in oldsize..newsize */
1225 	if (head < oldsize) {
1226 		i = oldsize - 1;
1227 		end = newsize;
1228 	} else {
1229 		/* Head did wrap; link newhead..newsize and 0..oldhead */
1230 		i = head;
1231 		end = newsize + (head - oldsize) + 1;
1232 	}
1233 
1234 	/*
1235 	 * Fix up hardware ring, being careful not to trample the active
1236 	 * section (tail -> head).
1237 	 */
1238 	for (; i < end; i++) {
1239 		KASSERT((i & (newsize - 1)) < tail ||
1240 		    (i & (newsize - 1)) >= head, ("trampling snake"));
1241 
1242 		next = newring[(i + 1) & (newsize - 1)];
1243 		hw = newring[i & (newsize - 1)]->u.dma;
1244 		hw->next = next->hw_desc_bus_addr;
1245 	}
1246 
1247 	free(ioat->ring, M_IOAT);
1248 	ioat->ring = newring;
1249 	ioat->ring_size_order = oldorder + 1;
1250 	ioat->tail = tail;
1251 	ioat->head = head;
1252 	error = 0;
1253 
1254 	mtx_unlock(&ioat->cleanup_lock);
1255 out:
1256 	if (error)
1257 		ioat_free_ring(ioat, (1 << (oldorder + 1)), newring);
1258 	return (error);
1259 }
1260 
1261 static int
1262 ring_shrink(struct ioat_softc *ioat, uint32_t oldorder,
1263     struct ioat_descriptor **newring)
1264 {
1265 	struct ioat_dma_hw_descriptor *hw;
1266 	struct ioat_descriptor *ent, *next;
1267 	uint32_t oldsize, newsize, current_idx, new_idx, i;
1268 	int error;
1269 
1270 	CTR0(KTR_IOAT, __func__);
1271 
1272 	mtx_assert(&ioat->submit_lock, MA_OWNED);
1273 
1274 	if (oldorder != ioat->ring_size_order || oldorder <= IOAT_MIN_ORDER) {
1275 		error = EINVAL;
1276 		goto out_unlocked;
1277 	}
1278 
1279 	oldsize = (1 << oldorder);
1280 	newsize = (1 << (oldorder - 1));
1281 
1282 	mtx_lock(&ioat->cleanup_lock);
1283 
1284 	/* Can't shrink below current active set! */
1285 	if (ioat_get_active(ioat) >= newsize) {
1286 		error = ENOMEM;
1287 		goto out;
1288 	}
1289 
1290 	/*
1291 	 * Copy current descriptors to the new ring, dropping the removed
1292 	 * descriptors.
1293 	 */
1294 	for (i = 0; i < newsize; i++) {
1295 		current_idx = (ioat->tail + i) & (oldsize - 1);
1296 		new_idx = (ioat->tail + i) & (newsize - 1);
1297 
1298 		newring[new_idx] = ioat->ring[current_idx];
1299 		newring[new_idx]->id = new_idx;
1300 	}
1301 
1302 	/* Free deleted descriptors */
1303 	for (i = newsize; i < oldsize; i++) {
1304 		ent = ioat_get_ring_entry(ioat, ioat->tail + i);
1305 		ioat_free_ring_entry(ioat, ent);
1306 	}
1307 
1308 	/* Fix up hardware ring. */
1309 	hw = newring[(ioat->tail + newsize - 1) & (newsize - 1)]->u.dma;
1310 	next = newring[(ioat->tail + newsize) & (newsize - 1)];
1311 	hw->next = next->hw_desc_bus_addr;
1312 
1313 	free(ioat->ring, M_IOAT);
1314 	ioat->ring = newring;
1315 	ioat->ring_size_order = oldorder - 1;
1316 	error = 0;
1317 
1318 out:
1319 	mtx_unlock(&ioat->cleanup_lock);
1320 out_unlocked:
1321 	if (error)
1322 		ioat_free_ring(ioat, (1 << (oldorder - 1)), newring);
1323 	return (error);
1324 }
1325 
1326 static void
1327 ioat_halted_debug(struct ioat_softc *ioat, uint32_t chanerr)
1328 {
1329 	struct ioat_descriptor *desc;
1330 
1331 	ioat_log_message(0, "Channel halted (%b)\n", (int)chanerr,
1332 	    IOAT_CHANERR_STR);
1333 	if (chanerr == 0)
1334 		return;
1335 
1336 	mtx_assert(&ioat->cleanup_lock, MA_OWNED);
1337 
1338 	desc = ioat_get_ring_entry(ioat, ioat->tail + 0);
1339 	dump_descriptor(desc->u.raw);
1340 
1341 	desc = ioat_get_ring_entry(ioat, ioat->tail + 1);
1342 	dump_descriptor(desc->u.raw);
1343 }
1344 
1345 static void
1346 ioat_timer_callback(void *arg)
1347 {
1348 	struct ioat_descriptor **newring;
1349 	struct ioat_softc *ioat;
1350 	uint32_t order;
1351 
1352 	ioat = arg;
1353 	ioat_log_message(1, "%s\n", __func__);
1354 
1355 	if (ioat->is_completion_pending) {
1356 		ioat_process_events(ioat);
1357 		return;
1358 	}
1359 
1360 	/* Slowly scale the ring down if idle. */
1361 	mtx_lock(&ioat->submit_lock);
1362 	order = ioat->ring_size_order;
1363 	if (ioat->is_resize_pending || order == IOAT_MIN_ORDER) {
1364 		mtx_unlock(&ioat->submit_lock);
1365 		goto out;
1366 	}
1367 	ioat->is_resize_pending = TRUE;
1368 	mtx_unlock(&ioat->submit_lock);
1369 
1370 	newring = ioat_prealloc_ring(ioat, 1 << (order - 1), FALSE,
1371 	    M_NOWAIT);
1372 
1373 	mtx_lock(&ioat->submit_lock);
1374 	KASSERT(ioat->ring_size_order == order,
1375 	    ("resize_pending protects order"));
1376 
1377 	if (newring != NULL)
1378 		ring_shrink(ioat, order, newring);
1379 
1380 	ioat->is_resize_pending = FALSE;
1381 	mtx_unlock(&ioat->submit_lock);
1382 
1383 out:
1384 	if (ioat->ring_size_order > IOAT_MIN_ORDER)
1385 		callout_reset(&ioat->timer, 10 * hz,
1386 		    ioat_timer_callback, ioat);
1387 }
1388 
1389 /*
1390  * Support Functions
1391  */
1392 static void
1393 ioat_submit_single(struct ioat_softc *ioat)
1394 {
1395 
1396 	ioat_get(ioat, IOAT_ACTIVE_DESCR_REF);
1397 	atomic_add_rel_int(&ioat->head, 1);
1398 	atomic_add_rel_int(&ioat->hw_head, 1);
1399 
1400 	if (!ioat->is_completion_pending) {
1401 		ioat->is_completion_pending = TRUE;
1402 		callout_reset(&ioat->timer, IOAT_INTR_TIMO,
1403 		    ioat_timer_callback, ioat);
1404 	}
1405 
1406 	ioat->stats.descriptors_submitted++;
1407 }
1408 
1409 static int
1410 ioat_reset_hw(struct ioat_softc *ioat)
1411 {
1412 	uint64_t status;
1413 	uint32_t chanerr;
1414 	unsigned timeout;
1415 	int error;
1416 
1417 	mtx_lock(IOAT_REFLK);
1418 	ioat->quiescing = TRUE;
1419 	ioat_drain_locked(ioat);
1420 	mtx_unlock(IOAT_REFLK);
1421 
1422 	status = ioat_get_chansts(ioat);
1423 	if (is_ioat_active(status) || is_ioat_idle(status))
1424 		ioat_suspend(ioat);
1425 
1426 	/* Wait at most 20 ms */
1427 	for (timeout = 0; (is_ioat_active(status) || is_ioat_idle(status)) &&
1428 	    timeout < 20; timeout++) {
1429 		DELAY(1000);
1430 		status = ioat_get_chansts(ioat);
1431 	}
1432 	if (timeout == 20) {
1433 		error = ETIMEDOUT;
1434 		goto out;
1435 	}
1436 
1437 	KASSERT(ioat_get_active(ioat) == 0, ("active after quiesce"));
1438 
1439 	chanerr = ioat_read_4(ioat, IOAT_CHANERR_OFFSET);
1440 	ioat_write_4(ioat, IOAT_CHANERR_OFFSET, chanerr);
1441 
1442 	/*
1443 	 * IOAT v3 workaround - CHANERRMSK_INT with 3E07h to masks out errors
1444 	 *  that can cause stability issues for IOAT v3.
1445 	 */
1446 	pci_write_config(ioat->device, IOAT_CFG_CHANERRMASK_INT_OFFSET, 0x3e07,
1447 	    4);
1448 	chanerr = pci_read_config(ioat->device, IOAT_CFG_CHANERR_INT_OFFSET, 4);
1449 	pci_write_config(ioat->device, IOAT_CFG_CHANERR_INT_OFFSET, chanerr, 4);
1450 
1451 	/*
1452 	 * BDXDE and BWD models reset MSI-X registers on device reset.
1453 	 * Save/restore their contents manually.
1454 	 */
1455 	if (ioat_model_resets_msix(ioat)) {
1456 		ioat_log_message(1, "device resets MSI-X registers; saving\n");
1457 		pci_save_state(ioat->device);
1458 	}
1459 
1460 	ioat_reset(ioat);
1461 
1462 	/* Wait at most 20 ms */
1463 	for (timeout = 0; ioat_reset_pending(ioat) && timeout < 20; timeout++)
1464 		DELAY(1000);
1465 	if (timeout == 20) {
1466 		error = ETIMEDOUT;
1467 		goto out;
1468 	}
1469 
1470 	if (ioat_model_resets_msix(ioat)) {
1471 		ioat_log_message(1, "device resets registers; restored\n");
1472 		pci_restore_state(ioat->device);
1473 	}
1474 
1475 	/* Reset attempts to return the hardware to "halted." */
1476 	status = ioat_get_chansts(ioat);
1477 	if (is_ioat_active(status) || is_ioat_idle(status)) {
1478 		/* So this really shouldn't happen... */
1479 		ioat_log_message(0, "Device is active after a reset?\n");
1480 		ioat_write_chanctrl(ioat, IOAT_CHANCTRL_RUN);
1481 		error = 0;
1482 		goto out;
1483 	}
1484 
1485 	chanerr = ioat_read_4(ioat, IOAT_CHANERR_OFFSET);
1486 	if (chanerr != 0) {
1487 		mtx_lock(&ioat->cleanup_lock);
1488 		ioat_halted_debug(ioat, chanerr);
1489 		mtx_unlock(&ioat->cleanup_lock);
1490 		error = EIO;
1491 		goto out;
1492 	}
1493 
1494 	/*
1495 	 * Bring device back online after reset.  Writing CHAINADDR brings the
1496 	 * device back to active.
1497 	 *
1498 	 * The internal ring counter resets to zero, so we have to start over
1499 	 * at zero as well.
1500 	 */
1501 	ioat->tail = ioat->head = ioat->hw_head = 0;
1502 	ioat->last_seen = 0;
1503 
1504 	ioat_write_chanctrl(ioat, IOAT_CHANCTRL_RUN);
1505 	ioat_write_chancmp(ioat, ioat->comp_update_bus_addr);
1506 	ioat_write_chainaddr(ioat, ioat->ring[0]->hw_desc_bus_addr);
1507 	error = 0;
1508 
1509 out:
1510 	mtx_lock(IOAT_REFLK);
1511 	ioat->quiescing = FALSE;
1512 	mtx_unlock(IOAT_REFLK);
1513 
1514 	if (error == 0)
1515 		error = ioat_start_channel(ioat);
1516 
1517 	return (error);
1518 }
1519 
1520 static int
1521 sysctl_handle_chansts(SYSCTL_HANDLER_ARGS)
1522 {
1523 	struct ioat_softc *ioat;
1524 	struct sbuf sb;
1525 	uint64_t status;
1526 	int error;
1527 
1528 	ioat = arg1;
1529 
1530 	status = ioat_get_chansts(ioat) & IOAT_CHANSTS_STATUS;
1531 
1532 	sbuf_new_for_sysctl(&sb, NULL, 256, req);
1533 	switch (status) {
1534 	case IOAT_CHANSTS_ACTIVE:
1535 		sbuf_printf(&sb, "ACTIVE");
1536 		break;
1537 	case IOAT_CHANSTS_IDLE:
1538 		sbuf_printf(&sb, "IDLE");
1539 		break;
1540 	case IOAT_CHANSTS_SUSPENDED:
1541 		sbuf_printf(&sb, "SUSPENDED");
1542 		break;
1543 	case IOAT_CHANSTS_HALTED:
1544 		sbuf_printf(&sb, "HALTED");
1545 		break;
1546 	case IOAT_CHANSTS_ARMED:
1547 		sbuf_printf(&sb, "ARMED");
1548 		break;
1549 	default:
1550 		sbuf_printf(&sb, "UNKNOWN");
1551 		break;
1552 	}
1553 	error = sbuf_finish(&sb);
1554 	sbuf_delete(&sb);
1555 
1556 	if (error != 0 || req->newptr == NULL)
1557 		return (error);
1558 	return (EINVAL);
1559 }
1560 
1561 static int
1562 sysctl_handle_dpi(SYSCTL_HANDLER_ARGS)
1563 {
1564 	struct ioat_softc *ioat;
1565 	struct sbuf sb;
1566 #define	PRECISION	"1"
1567 	const uintmax_t factor = 10;
1568 	uintmax_t rate;
1569 	int error;
1570 
1571 	ioat = arg1;
1572 	sbuf_new_for_sysctl(&sb, NULL, 16, req);
1573 
1574 	if (ioat->stats.interrupts == 0) {
1575 		sbuf_printf(&sb, "NaN");
1576 		goto out;
1577 	}
1578 	rate = ioat->stats.descriptors_processed * factor /
1579 	    ioat->stats.interrupts;
1580 	sbuf_printf(&sb, "%ju.%." PRECISION "ju", rate / factor,
1581 	    rate % factor);
1582 #undef	PRECISION
1583 out:
1584 	error = sbuf_finish(&sb);
1585 	sbuf_delete(&sb);
1586 	if (error != 0 || req->newptr == NULL)
1587 		return (error);
1588 	return (EINVAL);
1589 }
1590 
1591 static int
1592 sysctl_handle_error(SYSCTL_HANDLER_ARGS)
1593 {
1594 	struct ioat_descriptor *desc;
1595 	struct ioat_softc *ioat;
1596 	int error, arg;
1597 
1598 	ioat = arg1;
1599 
1600 	arg = 0;
1601 	error = SYSCTL_OUT(req, &arg, sizeof(arg));
1602 	if (error != 0 || req->newptr == NULL)
1603 		return (error);
1604 
1605 	error = SYSCTL_IN(req, &arg, sizeof(arg));
1606 	if (error != 0)
1607 		return (error);
1608 
1609 	if (arg != 0) {
1610 		ioat_acquire(&ioat->dmaengine);
1611 		desc = ioat_op_generic(ioat, IOAT_OP_COPY, 1,
1612 		    0xffff000000000000ull, 0xffff000000000000ull, NULL, NULL,
1613 		    0);
1614 		if (desc == NULL)
1615 			error = ENOMEM;
1616 		else
1617 			ioat_submit_single(ioat);
1618 		ioat_release(&ioat->dmaengine);
1619 	}
1620 	return (error);
1621 }
1622 
1623 static int
1624 sysctl_handle_reset(SYSCTL_HANDLER_ARGS)
1625 {
1626 	struct ioat_softc *ioat;
1627 	int error, arg;
1628 
1629 	ioat = arg1;
1630 
1631 	arg = 0;
1632 	error = SYSCTL_OUT(req, &arg, sizeof(arg));
1633 	if (error != 0 || req->newptr == NULL)
1634 		return (error);
1635 
1636 	error = SYSCTL_IN(req, &arg, sizeof(arg));
1637 	if (error != 0)
1638 		return (error);
1639 
1640 	if (arg != 0)
1641 		error = ioat_reset_hw(ioat);
1642 
1643 	return (error);
1644 }
1645 
1646 static void
1647 dump_descriptor(void *hw_desc)
1648 {
1649 	int i, j;
1650 
1651 	for (i = 0; i < 2; i++) {
1652 		for (j = 0; j < 8; j++)
1653 			printf("%08x ", ((uint32_t *)hw_desc)[i * 8 + j]);
1654 		printf("\n");
1655 	}
1656 }
1657 
1658 static void
1659 ioat_setup_sysctl(device_t device)
1660 {
1661 	struct sysctl_oid_list *par, *statpar, *state, *hammer;
1662 	struct sysctl_ctx_list *ctx;
1663 	struct sysctl_oid *tree, *tmp;
1664 	struct ioat_softc *ioat;
1665 
1666 	ioat = DEVICE2SOFTC(device);
1667 	ctx = device_get_sysctl_ctx(device);
1668 	tree = device_get_sysctl_tree(device);
1669 	par = SYSCTL_CHILDREN(tree);
1670 
1671 	SYSCTL_ADD_INT(ctx, par, OID_AUTO, "version", CTLFLAG_RD,
1672 	    &ioat->version, 0, "HW version (0xMM form)");
1673 	SYSCTL_ADD_UINT(ctx, par, OID_AUTO, "max_xfer_size", CTLFLAG_RD,
1674 	    &ioat->max_xfer_size, 0, "HW maximum transfer size");
1675 	SYSCTL_ADD_INT(ctx, par, OID_AUTO, "intrdelay_supported", CTLFLAG_RD,
1676 	    &ioat->intrdelay_supported, 0, "Is INTRDELAY supported");
1677 	SYSCTL_ADD_U16(ctx, par, OID_AUTO, "intrdelay_max", CTLFLAG_RD,
1678 	    &ioat->intrdelay_max, 0,
1679 	    "Maximum configurable INTRDELAY on this channel (microseconds)");
1680 
1681 	tmp = SYSCTL_ADD_NODE(ctx, par, OID_AUTO, "state", CTLFLAG_RD, NULL,
1682 	    "IOAT channel internal state");
1683 	state = SYSCTL_CHILDREN(tmp);
1684 
1685 	SYSCTL_ADD_UINT(ctx, state, OID_AUTO, "ring_size_order", CTLFLAG_RD,
1686 	    &ioat->ring_size_order, 0, "SW descriptor ring size order");
1687 	SYSCTL_ADD_UINT(ctx, state, OID_AUTO, "head", CTLFLAG_RD, &ioat->head,
1688 	    0, "SW descriptor head pointer index");
1689 	SYSCTL_ADD_UINT(ctx, state, OID_AUTO, "tail", CTLFLAG_RD, &ioat->tail,
1690 	    0, "SW descriptor tail pointer index");
1691 	SYSCTL_ADD_UINT(ctx, state, OID_AUTO, "hw_head", CTLFLAG_RD,
1692 	    &ioat->hw_head, 0, "HW DMACOUNT");
1693 
1694 	SYSCTL_ADD_UQUAD(ctx, state, OID_AUTO, "last_completion", CTLFLAG_RD,
1695 	    ioat->comp_update, "HW addr of last completion");
1696 
1697 	SYSCTL_ADD_INT(ctx, state, OID_AUTO, "is_resize_pending", CTLFLAG_RD,
1698 	    &ioat->is_resize_pending, 0, "resize pending");
1699 	SYSCTL_ADD_INT(ctx, state, OID_AUTO, "is_completion_pending",
1700 	    CTLFLAG_RD, &ioat->is_completion_pending, 0, "completion pending");
1701 	SYSCTL_ADD_INT(ctx, state, OID_AUTO, "is_reset_pending", CTLFLAG_RD,
1702 	    &ioat->is_reset_pending, 0, "reset pending");
1703 	SYSCTL_ADD_INT(ctx, state, OID_AUTO, "is_channel_running", CTLFLAG_RD,
1704 	    &ioat->is_channel_running, 0, "channel running");
1705 
1706 	SYSCTL_ADD_PROC(ctx, state, OID_AUTO, "chansts",
1707 	    CTLTYPE_STRING | CTLFLAG_RD, ioat, 0, sysctl_handle_chansts, "A",
1708 	    "String of the channel status");
1709 
1710 	SYSCTL_ADD_U16(ctx, state, OID_AUTO, "intrdelay", CTLFLAG_RD,
1711 	    &ioat->cached_intrdelay, 0,
1712 	    "Current INTRDELAY on this channel (cached, microseconds)");
1713 
1714 	tmp = SYSCTL_ADD_NODE(ctx, par, OID_AUTO, "hammer", CTLFLAG_RD, NULL,
1715 	    "Big hammers (mostly for testing)");
1716 	hammer = SYSCTL_CHILDREN(tmp);
1717 
1718 	SYSCTL_ADD_PROC(ctx, hammer, OID_AUTO, "force_hw_reset",
1719 	    CTLTYPE_INT | CTLFLAG_RW, ioat, 0, sysctl_handle_reset, "I",
1720 	    "Set to non-zero to reset the hardware");
1721 	SYSCTL_ADD_PROC(ctx, hammer, OID_AUTO, "force_hw_error",
1722 	    CTLTYPE_INT | CTLFLAG_RW, ioat, 0, sysctl_handle_error, "I",
1723 	    "Set to non-zero to inject a recoverable hardware error");
1724 
1725 	tmp = SYSCTL_ADD_NODE(ctx, par, OID_AUTO, "stats", CTLFLAG_RD, NULL,
1726 	    "IOAT channel statistics");
1727 	statpar = SYSCTL_CHILDREN(tmp);
1728 
1729 	SYSCTL_ADD_UQUAD(ctx, statpar, OID_AUTO, "interrupts", CTLFLAG_RW,
1730 	    &ioat->stats.interrupts,
1731 	    "Number of interrupts processed on this channel");
1732 	SYSCTL_ADD_UQUAD(ctx, statpar, OID_AUTO, "descriptors", CTLFLAG_RW,
1733 	    &ioat->stats.descriptors_processed,
1734 	    "Number of descriptors processed on this channel");
1735 	SYSCTL_ADD_UQUAD(ctx, statpar, OID_AUTO, "submitted", CTLFLAG_RW,
1736 	    &ioat->stats.descriptors_submitted,
1737 	    "Number of descriptors submitted to this channel");
1738 	SYSCTL_ADD_UQUAD(ctx, statpar, OID_AUTO, "errored", CTLFLAG_RW,
1739 	    &ioat->stats.descriptors_error,
1740 	    "Number of descriptors failed by channel errors");
1741 	SYSCTL_ADD_U32(ctx, statpar, OID_AUTO, "halts", CTLFLAG_RW,
1742 	    &ioat->stats.channel_halts, 0,
1743 	    "Number of times the channel has halted");
1744 	SYSCTL_ADD_U32(ctx, statpar, OID_AUTO, "last_halt_chanerr", CTLFLAG_RW,
1745 	    &ioat->stats.last_halt_chanerr, 0,
1746 	    "The raw CHANERR when the channel was last halted");
1747 
1748 	SYSCTL_ADD_PROC(ctx, statpar, OID_AUTO, "desc_per_interrupt",
1749 	    CTLTYPE_STRING | CTLFLAG_RD, ioat, 0, sysctl_handle_dpi, "A",
1750 	    "Descriptors per interrupt");
1751 }
1752 
1753 static inline struct ioat_softc *
1754 ioat_get(struct ioat_softc *ioat, enum ioat_ref_kind kind)
1755 {
1756 	uint32_t old;
1757 
1758 	KASSERT(kind < IOAT_NUM_REF_KINDS, ("bogus"));
1759 
1760 	old = atomic_fetchadd_32(&ioat->refcnt, 1);
1761 	KASSERT(old < UINT32_MAX, ("refcnt overflow"));
1762 
1763 #ifdef INVARIANTS
1764 	old = atomic_fetchadd_32(&ioat->refkinds[kind], 1);
1765 	KASSERT(old < UINT32_MAX, ("refcnt kind overflow"));
1766 #endif
1767 
1768 	return (ioat);
1769 }
1770 
1771 static inline void
1772 ioat_putn(struct ioat_softc *ioat, uint32_t n, enum ioat_ref_kind kind)
1773 {
1774 
1775 	_ioat_putn(ioat, n, kind, FALSE);
1776 }
1777 
1778 static inline void
1779 ioat_putn_locked(struct ioat_softc *ioat, uint32_t n, enum ioat_ref_kind kind)
1780 {
1781 
1782 	_ioat_putn(ioat, n, kind, TRUE);
1783 }
1784 
1785 static inline void
1786 _ioat_putn(struct ioat_softc *ioat, uint32_t n, enum ioat_ref_kind kind,
1787     boolean_t locked)
1788 {
1789 	uint32_t old;
1790 
1791 	KASSERT(kind < IOAT_NUM_REF_KINDS, ("bogus"));
1792 
1793 	if (n == 0)
1794 		return;
1795 
1796 #ifdef INVARIANTS
1797 	old = atomic_fetchadd_32(&ioat->refkinds[kind], -n);
1798 	KASSERT(old >= n, ("refcnt kind underflow"));
1799 #endif
1800 
1801 	/* Skip acquiring the lock if resulting refcnt > 0. */
1802 	for (;;) {
1803 		old = ioat->refcnt;
1804 		if (old <= n)
1805 			break;
1806 		if (atomic_cmpset_32(&ioat->refcnt, old, old - n))
1807 			return;
1808 	}
1809 
1810 	if (locked)
1811 		mtx_assert(IOAT_REFLK, MA_OWNED);
1812 	else
1813 		mtx_lock(IOAT_REFLK);
1814 
1815 	old = atomic_fetchadd_32(&ioat->refcnt, -n);
1816 	KASSERT(old >= n, ("refcnt error"));
1817 
1818 	if (old == n)
1819 		wakeup(IOAT_REFLK);
1820 	if (!locked)
1821 		mtx_unlock(IOAT_REFLK);
1822 }
1823 
1824 static inline void
1825 ioat_put(struct ioat_softc *ioat, enum ioat_ref_kind kind)
1826 {
1827 
1828 	ioat_putn(ioat, 1, kind);
1829 }
1830 
1831 static void
1832 ioat_drain_locked(struct ioat_softc *ioat)
1833 {
1834 
1835 	mtx_assert(IOAT_REFLK, MA_OWNED);
1836 	while (ioat->refcnt > 0)
1837 		msleep(IOAT_REFLK, IOAT_REFLK, 0, "ioat_drain", 0);
1838 }
1839