xref: /freebsd/sys/dev/ioat/ioat.c (revision b6a05070fa77edc7ce6e60b61623fd806e807be6)
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_get_hwversion(bus_dmaengine_t dmaengine)
740 {
741 	struct ioat_softc *ioat;
742 
743 	ioat = to_ioat_softc(dmaengine);
744 	return (ioat->version);
745 }
746 
747 int
748 ioat_set_interrupt_coalesce(bus_dmaengine_t dmaengine, uint16_t delay)
749 {
750 	struct ioat_softc *ioat;
751 
752 	ioat = to_ioat_softc(dmaengine);
753 	if (!ioat->intrdelay_supported)
754 		return (ENODEV);
755 	if (delay > ioat->intrdelay_max)
756 		return (ERANGE);
757 
758 	ioat_write_2(ioat, IOAT_INTRDELAY_OFFSET, delay);
759 	ioat->cached_intrdelay =
760 	    ioat_read_2(ioat, IOAT_INTRDELAY_OFFSET) & IOAT_INTRDELAY_US_MASK;
761 	return (0);
762 }
763 
764 uint16_t
765 ioat_get_max_coalesce_period(bus_dmaengine_t dmaengine)
766 {
767 	struct ioat_softc *ioat;
768 
769 	ioat = to_ioat_softc(dmaengine);
770 	return (ioat->intrdelay_max);
771 }
772 
773 void
774 ioat_acquire(bus_dmaengine_t dmaengine)
775 {
776 	struct ioat_softc *ioat;
777 
778 	ioat = to_ioat_softc(dmaengine);
779 	mtx_lock(&ioat->submit_lock);
780 	CTR0(KTR_IOAT, __func__);
781 }
782 
783 void
784 ioat_release(bus_dmaengine_t dmaengine)
785 {
786 	struct ioat_softc *ioat;
787 
788 	ioat = to_ioat_softc(dmaengine);
789 	CTR0(KTR_IOAT, __func__);
790 	ioat_write_2(ioat, IOAT_DMACOUNT_OFFSET, (uint16_t)ioat->hw_head);
791 	mtx_unlock(&ioat->submit_lock);
792 }
793 
794 static struct ioat_descriptor *
795 ioat_op_generic(struct ioat_softc *ioat, uint8_t op,
796     uint32_t size, uint64_t src, uint64_t dst,
797     bus_dmaengine_callback_t callback_fn, void *callback_arg,
798     uint32_t flags)
799 {
800 	struct ioat_generic_hw_descriptor *hw_desc;
801 	struct ioat_descriptor *desc;
802 	int mflags;
803 
804 	mtx_assert(&ioat->submit_lock, MA_OWNED);
805 
806 	KASSERT((flags & ~DMA_ALL_FLAGS) == 0, ("Unrecognized flag(s): %#x",
807 		flags & ~DMA_ALL_FLAGS));
808 	if ((flags & DMA_NO_WAIT) != 0)
809 		mflags = M_NOWAIT;
810 	else
811 		mflags = M_WAITOK;
812 
813 	if (size > ioat->max_xfer_size) {
814 		ioat_log_message(0, "%s: max_xfer_size = %d, requested = %u\n",
815 		    __func__, ioat->max_xfer_size, (unsigned)size);
816 		return (NULL);
817 	}
818 
819 	if (ioat_reserve_space(ioat, 1, mflags) != 0)
820 		return (NULL);
821 
822 	desc = ioat_get_ring_entry(ioat, ioat->head);
823 	hw_desc = desc->u.generic;
824 
825 	hw_desc->u.control_raw = 0;
826 	hw_desc->u.control_generic.op = op;
827 	hw_desc->u.control_generic.completion_update = 1;
828 
829 	if ((flags & DMA_INT_EN) != 0)
830 		hw_desc->u.control_generic.int_enable = 1;
831 
832 	hw_desc->size = size;
833 	hw_desc->src_addr = src;
834 	hw_desc->dest_addr = dst;
835 
836 	desc->bus_dmadesc.callback_fn = callback_fn;
837 	desc->bus_dmadesc.callback_arg = callback_arg;
838 	return (desc);
839 }
840 
841 struct bus_dmadesc *
842 ioat_null(bus_dmaengine_t dmaengine, bus_dmaengine_callback_t callback_fn,
843     void *callback_arg, uint32_t flags)
844 {
845 	struct ioat_dma_hw_descriptor *hw_desc;
846 	struct ioat_descriptor *desc;
847 	struct ioat_softc *ioat;
848 
849 	CTR0(KTR_IOAT, __func__);
850 	ioat = to_ioat_softc(dmaengine);
851 
852 	desc = ioat_op_generic(ioat, IOAT_OP_COPY, 8, 0, 0, callback_fn,
853 	    callback_arg, flags);
854 	if (desc == NULL)
855 		return (NULL);
856 
857 	hw_desc = desc->u.dma;
858 	hw_desc->u.control.null = 1;
859 	ioat_submit_single(ioat);
860 	return (&desc->bus_dmadesc);
861 }
862 
863 struct bus_dmadesc *
864 ioat_copy(bus_dmaengine_t dmaengine, bus_addr_t dst,
865     bus_addr_t src, bus_size_t len, bus_dmaengine_callback_t callback_fn,
866     void *callback_arg, uint32_t flags)
867 {
868 	struct ioat_dma_hw_descriptor *hw_desc;
869 	struct ioat_descriptor *desc;
870 	struct ioat_softc *ioat;
871 
872 	CTR0(KTR_IOAT, __func__);
873 	ioat = to_ioat_softc(dmaengine);
874 
875 	if (((src | dst) & (0xffffull << 48)) != 0) {
876 		ioat_log_message(0, "%s: High 16 bits of src/dst invalid\n",
877 		    __func__);
878 		return (NULL);
879 	}
880 
881 	desc = ioat_op_generic(ioat, IOAT_OP_COPY, len, src, dst, callback_fn,
882 	    callback_arg, flags);
883 	if (desc == NULL)
884 		return (NULL);
885 
886 	hw_desc = desc->u.dma;
887 	if (g_ioat_debug_level >= 3)
888 		dump_descriptor(hw_desc);
889 
890 	ioat_submit_single(ioat);
891 	return (&desc->bus_dmadesc);
892 }
893 
894 struct bus_dmadesc *
895 ioat_copy_8k_aligned(bus_dmaengine_t dmaengine, bus_addr_t dst1,
896     bus_addr_t dst2, bus_addr_t src1, bus_addr_t src2,
897     bus_dmaengine_callback_t callback_fn, void *callback_arg, uint32_t flags)
898 {
899 	struct ioat_dma_hw_descriptor *hw_desc;
900 	struct ioat_descriptor *desc;
901 	struct ioat_softc *ioat;
902 
903 	CTR0(KTR_IOAT, __func__);
904 	ioat = to_ioat_softc(dmaengine);
905 
906 	if (((src1 | src2 | dst1 | dst2) & (0xffffull << 48)) != 0) {
907 		ioat_log_message(0, "%s: High 16 bits of src/dst invalid\n",
908 		    __func__);
909 		return (NULL);
910 	}
911 	if (((src1 | src2 | dst1 | dst2) & PAGE_MASK) != 0) {
912 		ioat_log_message(0, "%s: Addresses must be page-aligned\n",
913 		    __func__);
914 		return (NULL);
915 	}
916 
917 	desc = ioat_op_generic(ioat, IOAT_OP_COPY, 2 * PAGE_SIZE, src1, dst1,
918 	    callback_fn, callback_arg, flags);
919 	if (desc == NULL)
920 		return (NULL);
921 
922 	hw_desc = desc->u.dma;
923 	if (src2 != src1 + PAGE_SIZE) {
924 		hw_desc->u.control.src_page_break = 1;
925 		hw_desc->next_src_addr = src2;
926 	}
927 	if (dst2 != dst1 + PAGE_SIZE) {
928 		hw_desc->u.control.dest_page_break = 1;
929 		hw_desc->next_dest_addr = dst2;
930 	}
931 
932 	if (g_ioat_debug_level >= 3)
933 		dump_descriptor(hw_desc);
934 
935 	ioat_submit_single(ioat);
936 	return (&desc->bus_dmadesc);
937 }
938 
939 struct bus_dmadesc *
940 ioat_blockfill(bus_dmaengine_t dmaengine, bus_addr_t dst, uint64_t fillpattern,
941     bus_size_t len, bus_dmaengine_callback_t callback_fn, void *callback_arg,
942     uint32_t flags)
943 {
944 	struct ioat_fill_hw_descriptor *hw_desc;
945 	struct ioat_descriptor *desc;
946 	struct ioat_softc *ioat;
947 
948 	CTR0(KTR_IOAT, __func__);
949 	ioat = to_ioat_softc(dmaengine);
950 
951 	if ((ioat->capabilities & IOAT_DMACAP_BFILL) == 0) {
952 		ioat_log_message(0, "%s: Device lacks BFILL capability\n",
953 		    __func__);
954 		return (NULL);
955 	}
956 
957 	if ((dst & (0xffffull << 48)) != 0) {
958 		ioat_log_message(0, "%s: High 16 bits of dst invalid\n",
959 		    __func__);
960 		return (NULL);
961 	}
962 
963 	desc = ioat_op_generic(ioat, IOAT_OP_FILL, len, fillpattern, dst,
964 	    callback_fn, callback_arg, flags);
965 	if (desc == NULL)
966 		return (NULL);
967 
968 	hw_desc = desc->u.fill;
969 	if (g_ioat_debug_level >= 3)
970 		dump_descriptor(hw_desc);
971 
972 	ioat_submit_single(ioat);
973 	return (&desc->bus_dmadesc);
974 }
975 
976 /*
977  * Ring Management
978  */
979 static inline uint32_t
980 ioat_get_active(struct ioat_softc *ioat)
981 {
982 
983 	return ((ioat->head - ioat->tail) & ((1 << ioat->ring_size_order) - 1));
984 }
985 
986 static inline uint32_t
987 ioat_get_ring_space(struct ioat_softc *ioat)
988 {
989 
990 	return ((1 << ioat->ring_size_order) - ioat_get_active(ioat) - 1);
991 }
992 
993 static struct ioat_descriptor *
994 ioat_alloc_ring_entry(struct ioat_softc *ioat, int mflags)
995 {
996 	struct ioat_generic_hw_descriptor *hw_desc;
997 	struct ioat_descriptor *desc;
998 	int error, busdmaflag;
999 
1000 	error = ENOMEM;
1001 	hw_desc = NULL;
1002 
1003 	if ((mflags & M_WAITOK) != 0)
1004 		busdmaflag = BUS_DMA_WAITOK;
1005 	else
1006 		busdmaflag = BUS_DMA_NOWAIT;
1007 
1008 	desc = malloc(sizeof(*desc), M_IOAT, mflags);
1009 	if (desc == NULL)
1010 		goto out;
1011 
1012 	bus_dmamem_alloc(ioat->hw_desc_tag, (void **)&hw_desc,
1013 	    BUS_DMA_ZERO | busdmaflag, &ioat->hw_desc_map);
1014 	if (hw_desc == NULL)
1015 		goto out;
1016 
1017 	memset(&desc->bus_dmadesc, 0, sizeof(desc->bus_dmadesc));
1018 	desc->u.generic = hw_desc;
1019 
1020 	error = bus_dmamap_load(ioat->hw_desc_tag, ioat->hw_desc_map, hw_desc,
1021 	    sizeof(*hw_desc), ioat_dmamap_cb, &desc->hw_desc_bus_addr,
1022 	    busdmaflag);
1023 	if (error)
1024 		goto out;
1025 
1026 out:
1027 	if (error) {
1028 		ioat_free_ring_entry(ioat, desc);
1029 		return (NULL);
1030 	}
1031 	return (desc);
1032 }
1033 
1034 static void
1035 ioat_free_ring_entry(struct ioat_softc *ioat, struct ioat_descriptor *desc)
1036 {
1037 
1038 	if (desc == NULL)
1039 		return;
1040 
1041 	if (desc->u.generic)
1042 		bus_dmamem_free(ioat->hw_desc_tag, desc->u.generic,
1043 		    ioat->hw_desc_map);
1044 	free(desc, M_IOAT);
1045 }
1046 
1047 /*
1048  * Reserves space in this IOAT descriptor ring by ensuring enough slots remain
1049  * for 'num_descs'.
1050  *
1051  * If mflags contains M_WAITOK, blocks until enough space is available.
1052  *
1053  * Returns zero on success, or an errno on error.  If num_descs is beyond the
1054  * maximum ring size, returns EINVAl; if allocation would block and mflags
1055  * contains M_NOWAIT, returns EAGAIN.
1056  *
1057  * Must be called with the submit_lock held; returns with the lock held.  The
1058  * lock may be dropped to allocate the ring.
1059  *
1060  * (The submit_lock is needed to add any entries to the ring, so callers are
1061  * assured enough room is available.)
1062  */
1063 static int
1064 ioat_reserve_space(struct ioat_softc *ioat, uint32_t num_descs, int mflags)
1065 {
1066 	struct ioat_descriptor **new_ring;
1067 	uint32_t order;
1068 	int error;
1069 
1070 	mtx_assert(&ioat->submit_lock, MA_OWNED);
1071 	error = 0;
1072 
1073 	if (num_descs < 1 || num_descs > (1 << IOAT_MAX_ORDER)) {
1074 		error = EINVAL;
1075 		goto out;
1076 	}
1077 	if (ioat->quiescing) {
1078 		error = ENXIO;
1079 		goto out;
1080 	}
1081 
1082 	for (;;) {
1083 		if (ioat_get_ring_space(ioat) >= num_descs)
1084 			goto out;
1085 
1086 		order = ioat->ring_size_order;
1087 		if (ioat->is_resize_pending || order == IOAT_MAX_ORDER) {
1088 			if ((mflags & M_WAITOK) != 0) {
1089 				msleep(&ioat->tail, &ioat->submit_lock, 0,
1090 				    "ioat_rsz", 0);
1091 				continue;
1092 			}
1093 
1094 			error = EAGAIN;
1095 			break;
1096 		}
1097 
1098 		ioat->is_resize_pending = TRUE;
1099 		for (;;) {
1100 			mtx_unlock(&ioat->submit_lock);
1101 
1102 			new_ring = ioat_prealloc_ring(ioat, 1 << (order + 1),
1103 			    TRUE, mflags);
1104 
1105 			mtx_lock(&ioat->submit_lock);
1106 			KASSERT(ioat->ring_size_order == order,
1107 			    ("is_resize_pending should protect order"));
1108 
1109 			if (new_ring == NULL) {
1110 				KASSERT((mflags & M_WAITOK) == 0,
1111 				    ("allocation failed"));
1112 				error = EAGAIN;
1113 				break;
1114 			}
1115 
1116 			error = ring_grow(ioat, order, new_ring);
1117 			if (error == 0)
1118 				break;
1119 		}
1120 		ioat->is_resize_pending = FALSE;
1121 		wakeup(&ioat->tail);
1122 		if (error)
1123 			break;
1124 	}
1125 
1126 out:
1127 	mtx_assert(&ioat->submit_lock, MA_OWNED);
1128 	return (error);
1129 }
1130 
1131 static struct ioat_descriptor **
1132 ioat_prealloc_ring(struct ioat_softc *ioat, uint32_t size, boolean_t need_dscr,
1133     int mflags)
1134 {
1135 	struct ioat_descriptor **ring;
1136 	uint32_t i;
1137 	int error;
1138 
1139 	KASSERT(size > 0 && powerof2(size), ("bogus size"));
1140 
1141 	ring = malloc(size * sizeof(*ring), M_IOAT, M_ZERO | mflags);
1142 	if (ring == NULL)
1143 		return (NULL);
1144 
1145 	if (need_dscr) {
1146 		error = ENOMEM;
1147 		for (i = size / 2; i < size; i++) {
1148 			ring[i] = ioat_alloc_ring_entry(ioat, mflags);
1149 			if (ring[i] == NULL)
1150 				goto out;
1151 			ring[i]->id = i;
1152 		}
1153 	}
1154 	error = 0;
1155 
1156 out:
1157 	if (error != 0 && ring != NULL) {
1158 		ioat_free_ring(ioat, size, ring);
1159 		ring = NULL;
1160 	}
1161 	return (ring);
1162 }
1163 
1164 static void
1165 ioat_free_ring(struct ioat_softc *ioat, uint32_t size,
1166     struct ioat_descriptor **ring)
1167 {
1168 	uint32_t i;
1169 
1170 	for (i = 0; i < size; i++) {
1171 		if (ring[i] != NULL)
1172 			ioat_free_ring_entry(ioat, ring[i]);
1173 	}
1174 	free(ring, M_IOAT);
1175 }
1176 
1177 static struct ioat_descriptor *
1178 ioat_get_ring_entry(struct ioat_softc *ioat, uint32_t index)
1179 {
1180 
1181 	return (ioat->ring[index % (1 << ioat->ring_size_order)]);
1182 }
1183 
1184 static int
1185 ring_grow(struct ioat_softc *ioat, uint32_t oldorder,
1186     struct ioat_descriptor **newring)
1187 {
1188 	struct ioat_descriptor *tmp, *next;
1189 	struct ioat_dma_hw_descriptor *hw;
1190 	uint32_t oldsize, newsize, head, tail, i, end;
1191 	int error;
1192 
1193 	CTR0(KTR_IOAT, __func__);
1194 
1195 	mtx_assert(&ioat->submit_lock, MA_OWNED);
1196 
1197 	if (oldorder != ioat->ring_size_order || oldorder >= IOAT_MAX_ORDER) {
1198 		error = EINVAL;
1199 		goto out;
1200 	}
1201 
1202 	oldsize = (1 << oldorder);
1203 	newsize = (1 << (oldorder + 1));
1204 
1205 	mtx_lock(&ioat->cleanup_lock);
1206 
1207 	head = ioat->head & (oldsize - 1);
1208 	tail = ioat->tail & (oldsize - 1);
1209 
1210 	/* Copy old descriptors to new ring */
1211 	for (i = 0; i < oldsize; i++)
1212 		newring[i] = ioat->ring[i];
1213 
1214 	/*
1215 	 * If head has wrapped but tail hasn't, we must swap some descriptors
1216 	 * around so that tail can increment directly to head.
1217 	 */
1218 	if (head < tail) {
1219 		for (i = 0; i <= head; i++) {
1220 			tmp = newring[oldsize + i];
1221 
1222 			newring[oldsize + i] = newring[i];
1223 			newring[oldsize + i]->id = oldsize + i;
1224 
1225 			newring[i] = tmp;
1226 			newring[i]->id = i;
1227 		}
1228 		head += oldsize;
1229 	}
1230 
1231 	KASSERT(head >= tail, ("invariants"));
1232 
1233 	/* Head didn't wrap; we only need to link in oldsize..newsize */
1234 	if (head < oldsize) {
1235 		i = oldsize - 1;
1236 		end = newsize;
1237 	} else {
1238 		/* Head did wrap; link newhead..newsize and 0..oldhead */
1239 		i = head;
1240 		end = newsize + (head - oldsize) + 1;
1241 	}
1242 
1243 	/*
1244 	 * Fix up hardware ring, being careful not to trample the active
1245 	 * section (tail -> head).
1246 	 */
1247 	for (; i < end; i++) {
1248 		KASSERT((i & (newsize - 1)) < tail ||
1249 		    (i & (newsize - 1)) >= head, ("trampling snake"));
1250 
1251 		next = newring[(i + 1) & (newsize - 1)];
1252 		hw = newring[i & (newsize - 1)]->u.dma;
1253 		hw->next = next->hw_desc_bus_addr;
1254 	}
1255 
1256 	free(ioat->ring, M_IOAT);
1257 	ioat->ring = newring;
1258 	ioat->ring_size_order = oldorder + 1;
1259 	ioat->tail = tail;
1260 	ioat->head = head;
1261 	error = 0;
1262 
1263 	mtx_unlock(&ioat->cleanup_lock);
1264 out:
1265 	if (error)
1266 		ioat_free_ring(ioat, (1 << (oldorder + 1)), newring);
1267 	return (error);
1268 }
1269 
1270 static int
1271 ring_shrink(struct ioat_softc *ioat, uint32_t oldorder,
1272     struct ioat_descriptor **newring)
1273 {
1274 	struct ioat_dma_hw_descriptor *hw;
1275 	struct ioat_descriptor *ent, *next;
1276 	uint32_t oldsize, newsize, current_idx, new_idx, i;
1277 	int error;
1278 
1279 	CTR0(KTR_IOAT, __func__);
1280 
1281 	mtx_assert(&ioat->submit_lock, MA_OWNED);
1282 
1283 	if (oldorder != ioat->ring_size_order || oldorder <= IOAT_MIN_ORDER) {
1284 		error = EINVAL;
1285 		goto out_unlocked;
1286 	}
1287 
1288 	oldsize = (1 << oldorder);
1289 	newsize = (1 << (oldorder - 1));
1290 
1291 	mtx_lock(&ioat->cleanup_lock);
1292 
1293 	/* Can't shrink below current active set! */
1294 	if (ioat_get_active(ioat) >= newsize) {
1295 		error = ENOMEM;
1296 		goto out;
1297 	}
1298 
1299 	/*
1300 	 * Copy current descriptors to the new ring, dropping the removed
1301 	 * descriptors.
1302 	 */
1303 	for (i = 0; i < newsize; i++) {
1304 		current_idx = (ioat->tail + i) & (oldsize - 1);
1305 		new_idx = (ioat->tail + i) & (newsize - 1);
1306 
1307 		newring[new_idx] = ioat->ring[current_idx];
1308 		newring[new_idx]->id = new_idx;
1309 	}
1310 
1311 	/* Free deleted descriptors */
1312 	for (i = newsize; i < oldsize; i++) {
1313 		ent = ioat_get_ring_entry(ioat, ioat->tail + i);
1314 		ioat_free_ring_entry(ioat, ent);
1315 	}
1316 
1317 	/* Fix up hardware ring. */
1318 	hw = newring[(ioat->tail + newsize - 1) & (newsize - 1)]->u.dma;
1319 	next = newring[(ioat->tail + newsize) & (newsize - 1)];
1320 	hw->next = next->hw_desc_bus_addr;
1321 
1322 	free(ioat->ring, M_IOAT);
1323 	ioat->ring = newring;
1324 	ioat->ring_size_order = oldorder - 1;
1325 	error = 0;
1326 
1327 out:
1328 	mtx_unlock(&ioat->cleanup_lock);
1329 out_unlocked:
1330 	if (error)
1331 		ioat_free_ring(ioat, (1 << (oldorder - 1)), newring);
1332 	return (error);
1333 }
1334 
1335 static void
1336 ioat_halted_debug(struct ioat_softc *ioat, uint32_t chanerr)
1337 {
1338 	struct ioat_descriptor *desc;
1339 
1340 	ioat_log_message(0, "Channel halted (%b)\n", (int)chanerr,
1341 	    IOAT_CHANERR_STR);
1342 	if (chanerr == 0)
1343 		return;
1344 
1345 	mtx_assert(&ioat->cleanup_lock, MA_OWNED);
1346 
1347 	desc = ioat_get_ring_entry(ioat, ioat->tail + 0);
1348 	dump_descriptor(desc->u.raw);
1349 
1350 	desc = ioat_get_ring_entry(ioat, ioat->tail + 1);
1351 	dump_descriptor(desc->u.raw);
1352 }
1353 
1354 static void
1355 ioat_timer_callback(void *arg)
1356 {
1357 	struct ioat_descriptor **newring;
1358 	struct ioat_softc *ioat;
1359 	uint32_t order;
1360 
1361 	ioat = arg;
1362 	ioat_log_message(1, "%s\n", __func__);
1363 
1364 	if (ioat->is_completion_pending) {
1365 		ioat_process_events(ioat);
1366 		return;
1367 	}
1368 
1369 	/* Slowly scale the ring down if idle. */
1370 	mtx_lock(&ioat->submit_lock);
1371 	order = ioat->ring_size_order;
1372 	if (ioat->is_resize_pending || order == IOAT_MIN_ORDER) {
1373 		mtx_unlock(&ioat->submit_lock);
1374 		goto out;
1375 	}
1376 	ioat->is_resize_pending = TRUE;
1377 	mtx_unlock(&ioat->submit_lock);
1378 
1379 	newring = ioat_prealloc_ring(ioat, 1 << (order - 1), FALSE,
1380 	    M_NOWAIT);
1381 
1382 	mtx_lock(&ioat->submit_lock);
1383 	KASSERT(ioat->ring_size_order == order,
1384 	    ("resize_pending protects order"));
1385 
1386 	if (newring != NULL)
1387 		ring_shrink(ioat, order, newring);
1388 
1389 	ioat->is_resize_pending = FALSE;
1390 	mtx_unlock(&ioat->submit_lock);
1391 
1392 out:
1393 	if (ioat->ring_size_order > IOAT_MIN_ORDER)
1394 		callout_reset(&ioat->timer, 10 * hz,
1395 		    ioat_timer_callback, ioat);
1396 }
1397 
1398 /*
1399  * Support Functions
1400  */
1401 static void
1402 ioat_submit_single(struct ioat_softc *ioat)
1403 {
1404 
1405 	ioat_get(ioat, IOAT_ACTIVE_DESCR_REF);
1406 	atomic_add_rel_int(&ioat->head, 1);
1407 	atomic_add_rel_int(&ioat->hw_head, 1);
1408 
1409 	if (!ioat->is_completion_pending) {
1410 		ioat->is_completion_pending = TRUE;
1411 		callout_reset(&ioat->timer, IOAT_INTR_TIMO,
1412 		    ioat_timer_callback, ioat);
1413 	}
1414 
1415 	ioat->stats.descriptors_submitted++;
1416 }
1417 
1418 static int
1419 ioat_reset_hw(struct ioat_softc *ioat)
1420 {
1421 	uint64_t status;
1422 	uint32_t chanerr;
1423 	unsigned timeout;
1424 	int error;
1425 
1426 	mtx_lock(IOAT_REFLK);
1427 	ioat->quiescing = TRUE;
1428 	ioat_drain_locked(ioat);
1429 	mtx_unlock(IOAT_REFLK);
1430 
1431 	status = ioat_get_chansts(ioat);
1432 	if (is_ioat_active(status) || is_ioat_idle(status))
1433 		ioat_suspend(ioat);
1434 
1435 	/* Wait at most 20 ms */
1436 	for (timeout = 0; (is_ioat_active(status) || is_ioat_idle(status)) &&
1437 	    timeout < 20; timeout++) {
1438 		DELAY(1000);
1439 		status = ioat_get_chansts(ioat);
1440 	}
1441 	if (timeout == 20) {
1442 		error = ETIMEDOUT;
1443 		goto out;
1444 	}
1445 
1446 	KASSERT(ioat_get_active(ioat) == 0, ("active after quiesce"));
1447 
1448 	chanerr = ioat_read_4(ioat, IOAT_CHANERR_OFFSET);
1449 	ioat_write_4(ioat, IOAT_CHANERR_OFFSET, chanerr);
1450 
1451 	/*
1452 	 * IOAT v3 workaround - CHANERRMSK_INT with 3E07h to masks out errors
1453 	 *  that can cause stability issues for IOAT v3.
1454 	 */
1455 	pci_write_config(ioat->device, IOAT_CFG_CHANERRMASK_INT_OFFSET, 0x3e07,
1456 	    4);
1457 	chanerr = pci_read_config(ioat->device, IOAT_CFG_CHANERR_INT_OFFSET, 4);
1458 	pci_write_config(ioat->device, IOAT_CFG_CHANERR_INT_OFFSET, chanerr, 4);
1459 
1460 	/*
1461 	 * BDXDE and BWD models reset MSI-X registers on device reset.
1462 	 * Save/restore their contents manually.
1463 	 */
1464 	if (ioat_model_resets_msix(ioat)) {
1465 		ioat_log_message(1, "device resets MSI-X registers; saving\n");
1466 		pci_save_state(ioat->device);
1467 	}
1468 
1469 	ioat_reset(ioat);
1470 
1471 	/* Wait at most 20 ms */
1472 	for (timeout = 0; ioat_reset_pending(ioat) && timeout < 20; timeout++)
1473 		DELAY(1000);
1474 	if (timeout == 20) {
1475 		error = ETIMEDOUT;
1476 		goto out;
1477 	}
1478 
1479 	if (ioat_model_resets_msix(ioat)) {
1480 		ioat_log_message(1, "device resets registers; restored\n");
1481 		pci_restore_state(ioat->device);
1482 	}
1483 
1484 	/* Reset attempts to return the hardware to "halted." */
1485 	status = ioat_get_chansts(ioat);
1486 	if (is_ioat_active(status) || is_ioat_idle(status)) {
1487 		/* So this really shouldn't happen... */
1488 		ioat_log_message(0, "Device is active after a reset?\n");
1489 		ioat_write_chanctrl(ioat, IOAT_CHANCTRL_RUN);
1490 		error = 0;
1491 		goto out;
1492 	}
1493 
1494 	chanerr = ioat_read_4(ioat, IOAT_CHANERR_OFFSET);
1495 	if (chanerr != 0) {
1496 		mtx_lock(&ioat->cleanup_lock);
1497 		ioat_halted_debug(ioat, chanerr);
1498 		mtx_unlock(&ioat->cleanup_lock);
1499 		error = EIO;
1500 		goto out;
1501 	}
1502 
1503 	/*
1504 	 * Bring device back online after reset.  Writing CHAINADDR brings the
1505 	 * device back to active.
1506 	 *
1507 	 * The internal ring counter resets to zero, so we have to start over
1508 	 * at zero as well.
1509 	 */
1510 	ioat->tail = ioat->head = ioat->hw_head = 0;
1511 	ioat->last_seen = 0;
1512 
1513 	ioat_write_chanctrl(ioat, IOAT_CHANCTRL_RUN);
1514 	ioat_write_chancmp(ioat, ioat->comp_update_bus_addr);
1515 	ioat_write_chainaddr(ioat, ioat->ring[0]->hw_desc_bus_addr);
1516 	error = 0;
1517 
1518 out:
1519 	mtx_lock(IOAT_REFLK);
1520 	ioat->quiescing = FALSE;
1521 	mtx_unlock(IOAT_REFLK);
1522 
1523 	if (error == 0)
1524 		error = ioat_start_channel(ioat);
1525 
1526 	return (error);
1527 }
1528 
1529 static int
1530 sysctl_handle_chansts(SYSCTL_HANDLER_ARGS)
1531 {
1532 	struct ioat_softc *ioat;
1533 	struct sbuf sb;
1534 	uint64_t status;
1535 	int error;
1536 
1537 	ioat = arg1;
1538 
1539 	status = ioat_get_chansts(ioat) & IOAT_CHANSTS_STATUS;
1540 
1541 	sbuf_new_for_sysctl(&sb, NULL, 256, req);
1542 	switch (status) {
1543 	case IOAT_CHANSTS_ACTIVE:
1544 		sbuf_printf(&sb, "ACTIVE");
1545 		break;
1546 	case IOAT_CHANSTS_IDLE:
1547 		sbuf_printf(&sb, "IDLE");
1548 		break;
1549 	case IOAT_CHANSTS_SUSPENDED:
1550 		sbuf_printf(&sb, "SUSPENDED");
1551 		break;
1552 	case IOAT_CHANSTS_HALTED:
1553 		sbuf_printf(&sb, "HALTED");
1554 		break;
1555 	case IOAT_CHANSTS_ARMED:
1556 		sbuf_printf(&sb, "ARMED");
1557 		break;
1558 	default:
1559 		sbuf_printf(&sb, "UNKNOWN");
1560 		break;
1561 	}
1562 	error = sbuf_finish(&sb);
1563 	sbuf_delete(&sb);
1564 
1565 	if (error != 0 || req->newptr == NULL)
1566 		return (error);
1567 	return (EINVAL);
1568 }
1569 
1570 static int
1571 sysctl_handle_dpi(SYSCTL_HANDLER_ARGS)
1572 {
1573 	struct ioat_softc *ioat;
1574 	struct sbuf sb;
1575 #define	PRECISION	"1"
1576 	const uintmax_t factor = 10;
1577 	uintmax_t rate;
1578 	int error;
1579 
1580 	ioat = arg1;
1581 	sbuf_new_for_sysctl(&sb, NULL, 16, req);
1582 
1583 	if (ioat->stats.interrupts == 0) {
1584 		sbuf_printf(&sb, "NaN");
1585 		goto out;
1586 	}
1587 	rate = ioat->stats.descriptors_processed * factor /
1588 	    ioat->stats.interrupts;
1589 	sbuf_printf(&sb, "%ju.%." PRECISION "ju", rate / factor,
1590 	    rate % factor);
1591 #undef	PRECISION
1592 out:
1593 	error = sbuf_finish(&sb);
1594 	sbuf_delete(&sb);
1595 	if (error != 0 || req->newptr == NULL)
1596 		return (error);
1597 	return (EINVAL);
1598 }
1599 
1600 static int
1601 sysctl_handle_error(SYSCTL_HANDLER_ARGS)
1602 {
1603 	struct ioat_descriptor *desc;
1604 	struct ioat_softc *ioat;
1605 	int error, arg;
1606 
1607 	ioat = arg1;
1608 
1609 	arg = 0;
1610 	error = SYSCTL_OUT(req, &arg, sizeof(arg));
1611 	if (error != 0 || req->newptr == NULL)
1612 		return (error);
1613 
1614 	error = SYSCTL_IN(req, &arg, sizeof(arg));
1615 	if (error != 0)
1616 		return (error);
1617 
1618 	if (arg != 0) {
1619 		ioat_acquire(&ioat->dmaengine);
1620 		desc = ioat_op_generic(ioat, IOAT_OP_COPY, 1,
1621 		    0xffff000000000000ull, 0xffff000000000000ull, NULL, NULL,
1622 		    0);
1623 		if (desc == NULL)
1624 			error = ENOMEM;
1625 		else
1626 			ioat_submit_single(ioat);
1627 		ioat_release(&ioat->dmaengine);
1628 	}
1629 	return (error);
1630 }
1631 
1632 static int
1633 sysctl_handle_reset(SYSCTL_HANDLER_ARGS)
1634 {
1635 	struct ioat_softc *ioat;
1636 	int error, arg;
1637 
1638 	ioat = arg1;
1639 
1640 	arg = 0;
1641 	error = SYSCTL_OUT(req, &arg, sizeof(arg));
1642 	if (error != 0 || req->newptr == NULL)
1643 		return (error);
1644 
1645 	error = SYSCTL_IN(req, &arg, sizeof(arg));
1646 	if (error != 0)
1647 		return (error);
1648 
1649 	if (arg != 0)
1650 		error = ioat_reset_hw(ioat);
1651 
1652 	return (error);
1653 }
1654 
1655 static void
1656 dump_descriptor(void *hw_desc)
1657 {
1658 	int i, j;
1659 
1660 	for (i = 0; i < 2; i++) {
1661 		for (j = 0; j < 8; j++)
1662 			printf("%08x ", ((uint32_t *)hw_desc)[i * 8 + j]);
1663 		printf("\n");
1664 	}
1665 }
1666 
1667 static void
1668 ioat_setup_sysctl(device_t device)
1669 {
1670 	struct sysctl_oid_list *par, *statpar, *state, *hammer;
1671 	struct sysctl_ctx_list *ctx;
1672 	struct sysctl_oid *tree, *tmp;
1673 	struct ioat_softc *ioat;
1674 
1675 	ioat = DEVICE2SOFTC(device);
1676 	ctx = device_get_sysctl_ctx(device);
1677 	tree = device_get_sysctl_tree(device);
1678 	par = SYSCTL_CHILDREN(tree);
1679 
1680 	SYSCTL_ADD_INT(ctx, par, OID_AUTO, "version", CTLFLAG_RD,
1681 	    &ioat->version, 0, "HW version (0xMM form)");
1682 	SYSCTL_ADD_UINT(ctx, par, OID_AUTO, "max_xfer_size", CTLFLAG_RD,
1683 	    &ioat->max_xfer_size, 0, "HW maximum transfer size");
1684 	SYSCTL_ADD_INT(ctx, par, OID_AUTO, "intrdelay_supported", CTLFLAG_RD,
1685 	    &ioat->intrdelay_supported, 0, "Is INTRDELAY supported");
1686 	SYSCTL_ADD_U16(ctx, par, OID_AUTO, "intrdelay_max", CTLFLAG_RD,
1687 	    &ioat->intrdelay_max, 0,
1688 	    "Maximum configurable INTRDELAY on this channel (microseconds)");
1689 
1690 	tmp = SYSCTL_ADD_NODE(ctx, par, OID_AUTO, "state", CTLFLAG_RD, NULL,
1691 	    "IOAT channel internal state");
1692 	state = SYSCTL_CHILDREN(tmp);
1693 
1694 	SYSCTL_ADD_UINT(ctx, state, OID_AUTO, "ring_size_order", CTLFLAG_RD,
1695 	    &ioat->ring_size_order, 0, "SW descriptor ring size order");
1696 	SYSCTL_ADD_UINT(ctx, state, OID_AUTO, "head", CTLFLAG_RD, &ioat->head,
1697 	    0, "SW descriptor head pointer index");
1698 	SYSCTL_ADD_UINT(ctx, state, OID_AUTO, "tail", CTLFLAG_RD, &ioat->tail,
1699 	    0, "SW descriptor tail pointer index");
1700 	SYSCTL_ADD_UINT(ctx, state, OID_AUTO, "hw_head", CTLFLAG_RD,
1701 	    &ioat->hw_head, 0, "HW DMACOUNT");
1702 
1703 	SYSCTL_ADD_UQUAD(ctx, state, OID_AUTO, "last_completion", CTLFLAG_RD,
1704 	    ioat->comp_update, "HW addr of last completion");
1705 
1706 	SYSCTL_ADD_INT(ctx, state, OID_AUTO, "is_resize_pending", CTLFLAG_RD,
1707 	    &ioat->is_resize_pending, 0, "resize pending");
1708 	SYSCTL_ADD_INT(ctx, state, OID_AUTO, "is_completion_pending",
1709 	    CTLFLAG_RD, &ioat->is_completion_pending, 0, "completion pending");
1710 	SYSCTL_ADD_INT(ctx, state, OID_AUTO, "is_reset_pending", CTLFLAG_RD,
1711 	    &ioat->is_reset_pending, 0, "reset pending");
1712 	SYSCTL_ADD_INT(ctx, state, OID_AUTO, "is_channel_running", CTLFLAG_RD,
1713 	    &ioat->is_channel_running, 0, "channel running");
1714 
1715 	SYSCTL_ADD_PROC(ctx, state, OID_AUTO, "chansts",
1716 	    CTLTYPE_STRING | CTLFLAG_RD, ioat, 0, sysctl_handle_chansts, "A",
1717 	    "String of the channel status");
1718 
1719 	SYSCTL_ADD_U16(ctx, state, OID_AUTO, "intrdelay", CTLFLAG_RD,
1720 	    &ioat->cached_intrdelay, 0,
1721 	    "Current INTRDELAY on this channel (cached, microseconds)");
1722 
1723 	tmp = SYSCTL_ADD_NODE(ctx, par, OID_AUTO, "hammer", CTLFLAG_RD, NULL,
1724 	    "Big hammers (mostly for testing)");
1725 	hammer = SYSCTL_CHILDREN(tmp);
1726 
1727 	SYSCTL_ADD_PROC(ctx, hammer, OID_AUTO, "force_hw_reset",
1728 	    CTLTYPE_INT | CTLFLAG_RW, ioat, 0, sysctl_handle_reset, "I",
1729 	    "Set to non-zero to reset the hardware");
1730 	SYSCTL_ADD_PROC(ctx, hammer, OID_AUTO, "force_hw_error",
1731 	    CTLTYPE_INT | CTLFLAG_RW, ioat, 0, sysctl_handle_error, "I",
1732 	    "Set to non-zero to inject a recoverable hardware error");
1733 
1734 	tmp = SYSCTL_ADD_NODE(ctx, par, OID_AUTO, "stats", CTLFLAG_RD, NULL,
1735 	    "IOAT channel statistics");
1736 	statpar = SYSCTL_CHILDREN(tmp);
1737 
1738 	SYSCTL_ADD_UQUAD(ctx, statpar, OID_AUTO, "interrupts", CTLFLAG_RW,
1739 	    &ioat->stats.interrupts,
1740 	    "Number of interrupts processed on this channel");
1741 	SYSCTL_ADD_UQUAD(ctx, statpar, OID_AUTO, "descriptors", CTLFLAG_RW,
1742 	    &ioat->stats.descriptors_processed,
1743 	    "Number of descriptors processed on this channel");
1744 	SYSCTL_ADD_UQUAD(ctx, statpar, OID_AUTO, "submitted", CTLFLAG_RW,
1745 	    &ioat->stats.descriptors_submitted,
1746 	    "Number of descriptors submitted to this channel");
1747 	SYSCTL_ADD_UQUAD(ctx, statpar, OID_AUTO, "errored", CTLFLAG_RW,
1748 	    &ioat->stats.descriptors_error,
1749 	    "Number of descriptors failed by channel errors");
1750 	SYSCTL_ADD_U32(ctx, statpar, OID_AUTO, "halts", CTLFLAG_RW,
1751 	    &ioat->stats.channel_halts, 0,
1752 	    "Number of times the channel has halted");
1753 	SYSCTL_ADD_U32(ctx, statpar, OID_AUTO, "last_halt_chanerr", CTLFLAG_RW,
1754 	    &ioat->stats.last_halt_chanerr, 0,
1755 	    "The raw CHANERR when the channel was last halted");
1756 
1757 	SYSCTL_ADD_PROC(ctx, statpar, OID_AUTO, "desc_per_interrupt",
1758 	    CTLTYPE_STRING | CTLFLAG_RD, ioat, 0, sysctl_handle_dpi, "A",
1759 	    "Descriptors per interrupt");
1760 }
1761 
1762 static inline struct ioat_softc *
1763 ioat_get(struct ioat_softc *ioat, enum ioat_ref_kind kind)
1764 {
1765 	uint32_t old;
1766 
1767 	KASSERT(kind < IOAT_NUM_REF_KINDS, ("bogus"));
1768 
1769 	old = atomic_fetchadd_32(&ioat->refcnt, 1);
1770 	KASSERT(old < UINT32_MAX, ("refcnt overflow"));
1771 
1772 #ifdef INVARIANTS
1773 	old = atomic_fetchadd_32(&ioat->refkinds[kind], 1);
1774 	KASSERT(old < UINT32_MAX, ("refcnt kind overflow"));
1775 #endif
1776 
1777 	return (ioat);
1778 }
1779 
1780 static inline void
1781 ioat_putn(struct ioat_softc *ioat, uint32_t n, enum ioat_ref_kind kind)
1782 {
1783 
1784 	_ioat_putn(ioat, n, kind, FALSE);
1785 }
1786 
1787 static inline void
1788 ioat_putn_locked(struct ioat_softc *ioat, uint32_t n, enum ioat_ref_kind kind)
1789 {
1790 
1791 	_ioat_putn(ioat, n, kind, TRUE);
1792 }
1793 
1794 static inline void
1795 _ioat_putn(struct ioat_softc *ioat, uint32_t n, enum ioat_ref_kind kind,
1796     boolean_t locked)
1797 {
1798 	uint32_t old;
1799 
1800 	KASSERT(kind < IOAT_NUM_REF_KINDS, ("bogus"));
1801 
1802 	if (n == 0)
1803 		return;
1804 
1805 #ifdef INVARIANTS
1806 	old = atomic_fetchadd_32(&ioat->refkinds[kind], -n);
1807 	KASSERT(old >= n, ("refcnt kind underflow"));
1808 #endif
1809 
1810 	/* Skip acquiring the lock if resulting refcnt > 0. */
1811 	for (;;) {
1812 		old = ioat->refcnt;
1813 		if (old <= n)
1814 			break;
1815 		if (atomic_cmpset_32(&ioat->refcnt, old, old - n))
1816 			return;
1817 	}
1818 
1819 	if (locked)
1820 		mtx_assert(IOAT_REFLK, MA_OWNED);
1821 	else
1822 		mtx_lock(IOAT_REFLK);
1823 
1824 	old = atomic_fetchadd_32(&ioat->refcnt, -n);
1825 	KASSERT(old >= n, ("refcnt error"));
1826 
1827 	if (old == n)
1828 		wakeup(IOAT_REFLK);
1829 	if (!locked)
1830 		mtx_unlock(IOAT_REFLK);
1831 }
1832 
1833 static inline void
1834 ioat_put(struct ioat_softc *ioat, enum ioat_ref_kind kind)
1835 {
1836 
1837 	ioat_putn(ioat, 1, kind);
1838 }
1839 
1840 static void
1841 ioat_drain_locked(struct ioat_softc *ioat)
1842 {
1843 
1844 	mtx_assert(IOAT_REFLK, MA_OWNED);
1845 	while (ioat->refcnt > 0)
1846 		msleep(IOAT_REFLK, IOAT_REFLK, 0, "ioat_drain", 0);
1847 }
1848