xref: /freebsd/sys/dev/ioat/ioat.c (revision 0aeed3e99367bed5755068d9218cd8041644ff2b)
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/taskqueue.h>
44 #include <sys/time.h>
45 #include <dev/pci/pcireg.h>
46 #include <dev/pci/pcivar.h>
47 #include <machine/bus.h>
48 #include <machine/resource.h>
49 #include <machine/stdarg.h>
50 
51 #include "ioat.h"
52 #include "ioat_hw.h"
53 #include "ioat_internal.h"
54 
55 #define	IOAT_INTR_TIMO	(hz / 10)
56 #define	IOAT_REFLK	(&ioat->submit_lock)
57 
58 static int ioat_probe(device_t device);
59 static int ioat_attach(device_t device);
60 static int ioat_detach(device_t device);
61 static int ioat_setup_intr(struct ioat_softc *ioat);
62 static int ioat_teardown_intr(struct ioat_softc *ioat);
63 static int ioat3_attach(device_t device);
64 static int ioat_start_channel(struct ioat_softc *ioat);
65 static int ioat_map_pci_bar(struct ioat_softc *ioat);
66 static void ioat_dmamap_cb(void *arg, bus_dma_segment_t *segs, int nseg,
67     int error);
68 static void ioat_interrupt_handler(void *arg);
69 static boolean_t ioat_model_resets_msix(struct ioat_softc *ioat);
70 static int chanerr_to_errno(uint32_t);
71 static void ioat_process_events(struct ioat_softc *ioat);
72 static inline uint32_t ioat_get_active(struct ioat_softc *ioat);
73 static inline uint32_t ioat_get_ring_space(struct ioat_softc *ioat);
74 static void ioat_free_ring(struct ioat_softc *, uint32_t size,
75     struct ioat_descriptor **);
76 static void ioat_free_ring_entry(struct ioat_softc *ioat,
77     struct ioat_descriptor *desc);
78 static struct ioat_descriptor *ioat_alloc_ring_entry(struct ioat_softc *,
79     int mflags);
80 static int ioat_reserve_space(struct ioat_softc *, uint32_t, int mflags);
81 static struct ioat_descriptor *ioat_get_ring_entry(struct ioat_softc *ioat,
82     uint32_t index);
83 static struct ioat_descriptor **ioat_prealloc_ring(struct ioat_softc *,
84     uint32_t size, boolean_t need_dscr, int mflags);
85 static int ring_grow(struct ioat_softc *, uint32_t oldorder,
86     struct ioat_descriptor **);
87 static int ring_shrink(struct ioat_softc *, uint32_t oldorder,
88     struct ioat_descriptor **);
89 static void ioat_halted_debug(struct ioat_softc *, uint32_t);
90 static void ioat_timer_callback(void *arg);
91 static void dump_descriptor(void *hw_desc);
92 static void ioat_submit_single(struct ioat_softc *ioat);
93 static void ioat_comp_update_map(void *arg, bus_dma_segment_t *seg, int nseg,
94     int error);
95 static int ioat_reset_hw(struct ioat_softc *ioat);
96 static void ioat_reset_hw_task(void *, int);
97 static void ioat_setup_sysctl(device_t device);
98 static int sysctl_handle_reset(SYSCTL_HANDLER_ARGS);
99 static inline struct ioat_softc *ioat_get(struct ioat_softc *,
100     enum ioat_ref_kind);
101 static inline void ioat_put(struct ioat_softc *, enum ioat_ref_kind);
102 static inline void _ioat_putn(struct ioat_softc *, uint32_t,
103     enum ioat_ref_kind, boolean_t);
104 static inline void ioat_putn(struct ioat_softc *, uint32_t,
105     enum ioat_ref_kind);
106 static inline void ioat_putn_locked(struct ioat_softc *, uint32_t,
107     enum ioat_ref_kind);
108 static void ioat_drain_locked(struct ioat_softc *);
109 
110 #define	ioat_log_message(v, ...) do {					\
111 	if ((v) <= g_ioat_debug_level) {				\
112 		device_printf(ioat->device, __VA_ARGS__);		\
113 	}								\
114 } while (0)
115 
116 MALLOC_DEFINE(M_IOAT, "ioat", "ioat driver memory allocations");
117 SYSCTL_NODE(_hw, OID_AUTO, ioat, CTLFLAG_RD, 0, "ioat node");
118 
119 static int g_force_legacy_interrupts;
120 SYSCTL_INT(_hw_ioat, OID_AUTO, force_legacy_interrupts, CTLFLAG_RDTUN,
121     &g_force_legacy_interrupts, 0, "Set to non-zero to force MSI-X disabled");
122 
123 int g_ioat_debug_level = 0;
124 SYSCTL_INT(_hw_ioat, OID_AUTO, debug_level, CTLFLAG_RWTUN, &g_ioat_debug_level,
125     0, "Set log level (0-3) for ioat(4). Higher is more verbose.");
126 
127 /*
128  * OS <-> Driver interface structures
129  */
130 static device_method_t ioat_pci_methods[] = {
131 	/* Device interface */
132 	DEVMETHOD(device_probe,     ioat_probe),
133 	DEVMETHOD(device_attach,    ioat_attach),
134 	DEVMETHOD(device_detach,    ioat_detach),
135 	{ 0, 0 }
136 };
137 
138 static driver_t ioat_pci_driver = {
139 	"ioat",
140 	ioat_pci_methods,
141 	sizeof(struct ioat_softc),
142 };
143 
144 static devclass_t ioat_devclass;
145 DRIVER_MODULE(ioat, pci, ioat_pci_driver, ioat_devclass, 0, 0);
146 MODULE_VERSION(ioat, 1);
147 
148 /*
149  * Private data structures
150  */
151 static struct ioat_softc *ioat_channel[IOAT_MAX_CHANNELS];
152 static int ioat_channel_index = 0;
153 SYSCTL_INT(_hw_ioat, OID_AUTO, channels, CTLFLAG_RD, &ioat_channel_index, 0,
154     "Number of IOAT channels attached");
155 
156 static struct _pcsid
157 {
158 	u_int32_t   type;
159 	const char  *desc;
160 } pci_ids[] = {
161 	{ 0x34308086, "TBG IOAT Ch0" },
162 	{ 0x34318086, "TBG IOAT Ch1" },
163 	{ 0x34328086, "TBG IOAT Ch2" },
164 	{ 0x34338086, "TBG IOAT Ch3" },
165 	{ 0x34298086, "TBG IOAT Ch4" },
166 	{ 0x342a8086, "TBG IOAT Ch5" },
167 	{ 0x342b8086, "TBG IOAT Ch6" },
168 	{ 0x342c8086, "TBG IOAT Ch7" },
169 
170 	{ 0x37108086, "JSF IOAT Ch0" },
171 	{ 0x37118086, "JSF IOAT Ch1" },
172 	{ 0x37128086, "JSF IOAT Ch2" },
173 	{ 0x37138086, "JSF IOAT Ch3" },
174 	{ 0x37148086, "JSF IOAT Ch4" },
175 	{ 0x37158086, "JSF IOAT Ch5" },
176 	{ 0x37168086, "JSF IOAT Ch6" },
177 	{ 0x37178086, "JSF IOAT Ch7" },
178 	{ 0x37188086, "JSF IOAT Ch0 (RAID)" },
179 	{ 0x37198086, "JSF IOAT Ch1 (RAID)" },
180 
181 	{ 0x3c208086, "SNB IOAT Ch0" },
182 	{ 0x3c218086, "SNB IOAT Ch1" },
183 	{ 0x3c228086, "SNB IOAT Ch2" },
184 	{ 0x3c238086, "SNB IOAT Ch3" },
185 	{ 0x3c248086, "SNB IOAT Ch4" },
186 	{ 0x3c258086, "SNB IOAT Ch5" },
187 	{ 0x3c268086, "SNB IOAT Ch6" },
188 	{ 0x3c278086, "SNB IOAT Ch7" },
189 	{ 0x3c2e8086, "SNB IOAT Ch0 (RAID)" },
190 	{ 0x3c2f8086, "SNB IOAT Ch1 (RAID)" },
191 
192 	{ 0x0e208086, "IVB IOAT Ch0" },
193 	{ 0x0e218086, "IVB IOAT Ch1" },
194 	{ 0x0e228086, "IVB IOAT Ch2" },
195 	{ 0x0e238086, "IVB IOAT Ch3" },
196 	{ 0x0e248086, "IVB IOAT Ch4" },
197 	{ 0x0e258086, "IVB IOAT Ch5" },
198 	{ 0x0e268086, "IVB IOAT Ch6" },
199 	{ 0x0e278086, "IVB IOAT Ch7" },
200 	{ 0x0e2e8086, "IVB IOAT Ch0 (RAID)" },
201 	{ 0x0e2f8086, "IVB IOAT Ch1 (RAID)" },
202 
203 	{ 0x2f208086, "HSW IOAT Ch0" },
204 	{ 0x2f218086, "HSW IOAT Ch1" },
205 	{ 0x2f228086, "HSW IOAT Ch2" },
206 	{ 0x2f238086, "HSW IOAT Ch3" },
207 	{ 0x2f248086, "HSW IOAT Ch4" },
208 	{ 0x2f258086, "HSW IOAT Ch5" },
209 	{ 0x2f268086, "HSW IOAT Ch6" },
210 	{ 0x2f278086, "HSW IOAT Ch7" },
211 	{ 0x2f2e8086, "HSW IOAT Ch0 (RAID)" },
212 	{ 0x2f2f8086, "HSW IOAT Ch1 (RAID)" },
213 
214 	{ 0x0c508086, "BWD IOAT Ch0" },
215 	{ 0x0c518086, "BWD IOAT Ch1" },
216 	{ 0x0c528086, "BWD IOAT Ch2" },
217 	{ 0x0c538086, "BWD IOAT Ch3" },
218 
219 	{ 0x6f508086, "BDXDE IOAT Ch0" },
220 	{ 0x6f518086, "BDXDE IOAT Ch1" },
221 	{ 0x6f528086, "BDXDE IOAT Ch2" },
222 	{ 0x6f538086, "BDXDE IOAT Ch3" },
223 
224 	{ 0x6f208086, "BDX IOAT Ch0" },
225 	{ 0x6f218086, "BDX IOAT Ch1" },
226 	{ 0x6f228086, "BDX IOAT Ch2" },
227 	{ 0x6f238086, "BDX IOAT Ch3" },
228 	{ 0x6f248086, "BDX IOAT Ch4" },
229 	{ 0x6f258086, "BDX IOAT Ch5" },
230 	{ 0x6f268086, "BDX IOAT Ch6" },
231 	{ 0x6f278086, "BDX IOAT Ch7" },
232 	{ 0x6f2e8086, "BDX IOAT Ch0 (RAID)" },
233 	{ 0x6f2f8086, "BDX IOAT Ch1 (RAID)" },
234 
235 	{ 0x00000000, NULL           }
236 };
237 
238 /*
239  * OS <-> Driver linkage functions
240  */
241 static int
242 ioat_probe(device_t device)
243 {
244 	struct _pcsid *ep;
245 	u_int32_t type;
246 
247 	type = pci_get_devid(device);
248 	for (ep = pci_ids; ep->type; ep++) {
249 		if (ep->type == type) {
250 			device_set_desc(device, ep->desc);
251 			return (0);
252 		}
253 	}
254 	return (ENXIO);
255 }
256 
257 static int
258 ioat_attach(device_t device)
259 {
260 	struct ioat_softc *ioat;
261 	int error;
262 
263 	ioat = DEVICE2SOFTC(device);
264 	ioat->device = device;
265 
266 	error = ioat_map_pci_bar(ioat);
267 	if (error != 0)
268 		goto err;
269 
270 	ioat->version = ioat_read_cbver(ioat);
271 	if (ioat->version < IOAT_VER_3_0) {
272 		error = ENODEV;
273 		goto err;
274 	}
275 
276 	error = ioat3_attach(device);
277 	if (error != 0)
278 		goto err;
279 
280 	error = pci_enable_busmaster(device);
281 	if (error != 0)
282 		goto err;
283 
284 	error = ioat_setup_intr(ioat);
285 	if (error != 0)
286 		goto err;
287 
288 	error = ioat_reset_hw(ioat);
289 	if (error != 0)
290 		goto err;
291 
292 	ioat_process_events(ioat);
293 	ioat_setup_sysctl(device);
294 
295 	ioat->chan_idx = ioat_channel_index;
296 	ioat_channel[ioat_channel_index++] = ioat;
297 	ioat_test_attach();
298 
299 err:
300 	if (error != 0)
301 		ioat_detach(device);
302 	return (error);
303 }
304 
305 static int
306 ioat_detach(device_t device)
307 {
308 	struct ioat_softc *ioat;
309 
310 	ioat = DEVICE2SOFTC(device);
311 
312 	ioat_test_detach();
313 	taskqueue_drain(taskqueue_thread, &ioat->reset_task);
314 
315 	mtx_lock(IOAT_REFLK);
316 	ioat->quiescing = TRUE;
317 	ioat_channel[ioat->chan_idx] = NULL;
318 
319 	ioat_drain_locked(ioat);
320 	mtx_unlock(IOAT_REFLK);
321 
322 	ioat_teardown_intr(ioat);
323 	callout_drain(&ioat->timer);
324 
325 	pci_disable_busmaster(device);
326 
327 	if (ioat->pci_resource != NULL)
328 		bus_release_resource(device, SYS_RES_MEMORY,
329 		    ioat->pci_resource_id, ioat->pci_resource);
330 
331 	if (ioat->ring != NULL)
332 		ioat_free_ring(ioat, 1 << ioat->ring_size_order, ioat->ring);
333 
334 	if (ioat->comp_update != NULL) {
335 		bus_dmamap_unload(ioat->comp_update_tag, ioat->comp_update_map);
336 		bus_dmamem_free(ioat->comp_update_tag, ioat->comp_update,
337 		    ioat->comp_update_map);
338 		bus_dma_tag_destroy(ioat->comp_update_tag);
339 	}
340 
341 	bus_dma_tag_destroy(ioat->hw_desc_tag);
342 
343 	return (0);
344 }
345 
346 static int
347 ioat_teardown_intr(struct ioat_softc *ioat)
348 {
349 
350 	if (ioat->tag != NULL)
351 		bus_teardown_intr(ioat->device, ioat->res, ioat->tag);
352 
353 	if (ioat->res != NULL)
354 		bus_release_resource(ioat->device, SYS_RES_IRQ,
355 		    rman_get_rid(ioat->res), ioat->res);
356 
357 	pci_release_msi(ioat->device);
358 	return (0);
359 }
360 
361 static int
362 ioat_start_channel(struct ioat_softc *ioat)
363 {
364 	uint64_t status;
365 	uint32_t chanerr;
366 	int i;
367 
368 	ioat_acquire(&ioat->dmaengine);
369 	ioat_null(&ioat->dmaengine, NULL, NULL, 0);
370 	ioat_release(&ioat->dmaengine);
371 
372 	for (i = 0; i < 100; i++) {
373 		DELAY(1);
374 		status = ioat_get_chansts(ioat);
375 		if (is_ioat_idle(status))
376 			return (0);
377 	}
378 
379 	chanerr = ioat_read_4(ioat, IOAT_CHANERR_OFFSET);
380 	ioat_log_message(0, "could not start channel: "
381 	    "status = %#jx error = %b\n", (uintmax_t)status, (int)chanerr,
382 	    IOAT_CHANERR_STR);
383 	return (ENXIO);
384 }
385 
386 /*
387  * Initialize Hardware
388  */
389 static int
390 ioat3_attach(device_t device)
391 {
392 	struct ioat_softc *ioat;
393 	struct ioat_descriptor **ring;
394 	struct ioat_descriptor *next;
395 	struct ioat_dma_hw_descriptor *dma_hw_desc;
396 	int i, num_descriptors;
397 	int error;
398 	uint8_t xfercap;
399 
400 	error = 0;
401 	ioat = DEVICE2SOFTC(device);
402 	ioat->capabilities = ioat_read_dmacapability(ioat);
403 
404 	ioat_log_message(1, "Capabilities: %b\n", (int)ioat->capabilities,
405 	    IOAT_DMACAP_STR);
406 
407 	xfercap = ioat_read_xfercap(ioat);
408 	ioat->max_xfer_size = 1 << xfercap;
409 
410 	ioat->intrdelay_supported = (ioat_read_2(ioat, IOAT_INTRDELAY_OFFSET) &
411 	    IOAT_INTRDELAY_SUPPORTED) != 0;
412 	if (ioat->intrdelay_supported)
413 		ioat->intrdelay_max = IOAT_INTRDELAY_US_MASK;
414 
415 	/* TODO: need to check DCA here if we ever do XOR/PQ */
416 
417 	mtx_init(&ioat->submit_lock, "ioat_submit", NULL, MTX_DEF);
418 	mtx_init(&ioat->cleanup_lock, "ioat_cleanup", NULL, MTX_DEF);
419 	callout_init(&ioat->timer, 1);
420 	TASK_INIT(&ioat->reset_task, 0, ioat_reset_hw_task, ioat);
421 
422 	/* Establish lock order for Witness */
423 	mtx_lock(&ioat->submit_lock);
424 	mtx_lock(&ioat->cleanup_lock);
425 	mtx_unlock(&ioat->cleanup_lock);
426 	mtx_unlock(&ioat->submit_lock);
427 
428 	ioat->is_resize_pending = FALSE;
429 	ioat->is_completion_pending = FALSE;
430 	ioat->is_reset_pending = FALSE;
431 	ioat->is_channel_running = FALSE;
432 
433 	bus_dma_tag_create(bus_get_dma_tag(ioat->device), sizeof(uint64_t), 0x0,
434 	    BUS_SPACE_MAXADDR, BUS_SPACE_MAXADDR, NULL, NULL,
435 	    sizeof(uint64_t), 1, sizeof(uint64_t), 0, NULL, NULL,
436 	    &ioat->comp_update_tag);
437 
438 	error = bus_dmamem_alloc(ioat->comp_update_tag,
439 	    (void **)&ioat->comp_update, BUS_DMA_ZERO, &ioat->comp_update_map);
440 	if (ioat->comp_update == NULL)
441 		return (ENOMEM);
442 
443 	error = bus_dmamap_load(ioat->comp_update_tag, ioat->comp_update_map,
444 	    ioat->comp_update, sizeof(uint64_t), ioat_comp_update_map, ioat,
445 	    0);
446 	if (error != 0)
447 		return (error);
448 
449 	ioat->ring_size_order = IOAT_MIN_ORDER;
450 
451 	num_descriptors = 1 << ioat->ring_size_order;
452 
453 	bus_dma_tag_create(bus_get_dma_tag(ioat->device), 0x40, 0x0,
454 	    BUS_SPACE_MAXADDR, BUS_SPACE_MAXADDR, NULL, NULL,
455 	    sizeof(struct ioat_dma_hw_descriptor), 1,
456 	    sizeof(struct ioat_dma_hw_descriptor), 0, NULL, NULL,
457 	    &ioat->hw_desc_tag);
458 
459 	ioat->ring = malloc(num_descriptors * sizeof(*ring), M_IOAT,
460 	    M_ZERO | M_WAITOK);
461 	if (ioat->ring == NULL)
462 		return (ENOMEM);
463 
464 	ring = ioat->ring;
465 	for (i = 0; i < num_descriptors; i++) {
466 		ring[i] = ioat_alloc_ring_entry(ioat, M_WAITOK);
467 		if (ring[i] == NULL)
468 			return (ENOMEM);
469 
470 		ring[i]->id = i;
471 	}
472 
473 	for (i = 0; i < num_descriptors - 1; i++) {
474 		next = ring[i + 1];
475 		dma_hw_desc = ring[i]->u.dma;
476 
477 		dma_hw_desc->next = next->hw_desc_bus_addr;
478 	}
479 
480 	ring[i]->u.dma->next = ring[0]->hw_desc_bus_addr;
481 
482 	ioat->head = ioat->hw_head = 0;
483 	ioat->tail = 0;
484 	ioat->last_seen = 0;
485 	return (0);
486 }
487 
488 static int
489 ioat_map_pci_bar(struct ioat_softc *ioat)
490 {
491 
492 	ioat->pci_resource_id = PCIR_BAR(0);
493 	ioat->pci_resource = bus_alloc_resource_any(ioat->device,
494 	    SYS_RES_MEMORY, &ioat->pci_resource_id, RF_ACTIVE);
495 
496 	if (ioat->pci_resource == NULL) {
497 		ioat_log_message(0, "unable to allocate pci resource\n");
498 		return (ENODEV);
499 	}
500 
501 	ioat->pci_bus_tag = rman_get_bustag(ioat->pci_resource);
502 	ioat->pci_bus_handle = rman_get_bushandle(ioat->pci_resource);
503 	return (0);
504 }
505 
506 static void
507 ioat_comp_update_map(void *arg, bus_dma_segment_t *seg, int nseg, int error)
508 {
509 	struct ioat_softc *ioat = arg;
510 
511 	KASSERT(error == 0, ("%s: error:%d", __func__, error));
512 	ioat->comp_update_bus_addr = seg[0].ds_addr;
513 }
514 
515 static void
516 ioat_dmamap_cb(void *arg, bus_dma_segment_t *segs, int nseg, int error)
517 {
518 	bus_addr_t *baddr;
519 
520 	KASSERT(error == 0, ("%s: error:%d", __func__, error));
521 	baddr = arg;
522 	*baddr = segs->ds_addr;
523 }
524 
525 /*
526  * Interrupt setup and handlers
527  */
528 static int
529 ioat_setup_intr(struct ioat_softc *ioat)
530 {
531 	uint32_t num_vectors;
532 	int error;
533 	boolean_t use_msix;
534 	boolean_t force_legacy_interrupts;
535 
536 	use_msix = FALSE;
537 	force_legacy_interrupts = FALSE;
538 
539 	if (!g_force_legacy_interrupts && pci_msix_count(ioat->device) >= 1) {
540 		num_vectors = 1;
541 		pci_alloc_msix(ioat->device, &num_vectors);
542 		if (num_vectors == 1)
543 			use_msix = TRUE;
544 	}
545 
546 	if (use_msix) {
547 		ioat->rid = 1;
548 		ioat->res = bus_alloc_resource_any(ioat->device, SYS_RES_IRQ,
549 		    &ioat->rid, RF_ACTIVE);
550 	} else {
551 		ioat->rid = 0;
552 		ioat->res = bus_alloc_resource_any(ioat->device, SYS_RES_IRQ,
553 		    &ioat->rid, RF_SHAREABLE | RF_ACTIVE);
554 	}
555 	if (ioat->res == NULL) {
556 		ioat_log_message(0, "bus_alloc_resource failed\n");
557 		return (ENOMEM);
558 	}
559 
560 	ioat->tag = NULL;
561 	error = bus_setup_intr(ioat->device, ioat->res, INTR_MPSAFE |
562 	    INTR_TYPE_MISC, NULL, ioat_interrupt_handler, ioat, &ioat->tag);
563 	if (error != 0) {
564 		ioat_log_message(0, "bus_setup_intr failed\n");
565 		return (error);
566 	}
567 
568 	ioat_write_intrctrl(ioat, IOAT_INTRCTRL_MASTER_INT_EN);
569 	return (0);
570 }
571 
572 static boolean_t
573 ioat_model_resets_msix(struct ioat_softc *ioat)
574 {
575 	u_int32_t pciid;
576 
577 	pciid = pci_get_devid(ioat->device);
578 	switch (pciid) {
579 		/* BWD: */
580 	case 0x0c508086:
581 	case 0x0c518086:
582 	case 0x0c528086:
583 	case 0x0c538086:
584 		/* BDXDE: */
585 	case 0x6f508086:
586 	case 0x6f518086:
587 	case 0x6f528086:
588 	case 0x6f538086:
589 		return (TRUE);
590 	}
591 
592 	return (FALSE);
593 }
594 
595 static void
596 ioat_interrupt_handler(void *arg)
597 {
598 	struct ioat_softc *ioat = arg;
599 
600 	ioat->stats.interrupts++;
601 	ioat_process_events(ioat);
602 }
603 
604 static int
605 chanerr_to_errno(uint32_t chanerr)
606 {
607 
608 	if (chanerr == 0)
609 		return (0);
610 	if ((chanerr & (IOAT_CHANERR_XSADDERR | IOAT_CHANERR_XDADDERR)) != 0)
611 		return (EFAULT);
612 	if ((chanerr & (IOAT_CHANERR_RDERR | IOAT_CHANERR_WDERR)) != 0)
613 		return (EIO);
614 	/* This one is probably our fault: */
615 	if ((chanerr & IOAT_CHANERR_NDADDERR) != 0)
616 		return (EIO);
617 	return (EIO);
618 }
619 
620 static void
621 ioat_process_events(struct ioat_softc *ioat)
622 {
623 	struct ioat_descriptor *desc;
624 	struct bus_dmadesc *dmadesc;
625 	uint64_t comp_update, status;
626 	uint32_t completed, chanerr;
627 	int error;
628 
629 	mtx_lock(&ioat->cleanup_lock);
630 
631 	completed = 0;
632 	comp_update = *ioat->comp_update;
633 	status = comp_update & IOAT_CHANSTS_COMPLETED_DESCRIPTOR_MASK;
634 
635 	CTR0(KTR_IOAT, __func__);
636 
637 	if (status == ioat->last_seen) {
638 		/*
639 		 * If we landed in process_events and nothing has been
640 		 * completed, check for a timeout due to channel halt.
641 		 */
642 		comp_update = ioat_get_chansts(ioat);
643 		goto out;
644 	}
645 
646 	while (1) {
647 		desc = ioat_get_ring_entry(ioat, ioat->tail);
648 		dmadesc = &desc->bus_dmadesc;
649 		CTR1(KTR_IOAT, "completing desc %d", ioat->tail);
650 
651 		if (dmadesc->callback_fn != NULL)
652 			dmadesc->callback_fn(dmadesc->callback_arg, 0);
653 
654 		completed++;
655 		ioat->tail++;
656 		if (desc->hw_desc_bus_addr == status)
657 			break;
658 	}
659 
660 	ioat->last_seen = desc->hw_desc_bus_addr;
661 
662 	if (ioat->head == ioat->tail) {
663 		ioat->is_completion_pending = FALSE;
664 		callout_reset(&ioat->timer, IOAT_INTR_TIMO,
665 		    ioat_timer_callback, ioat);
666 	}
667 
668 	ioat->stats.descriptors_processed += completed;
669 
670 out:
671 	ioat_write_chanctrl(ioat, IOAT_CHANCTRL_RUN);
672 	mtx_unlock(&ioat->cleanup_lock);
673 
674 	if (completed != 0) {
675 		ioat_putn(ioat, completed, IOAT_ACTIVE_DESCR_REF);
676 		wakeup(&ioat->tail);
677 	}
678 
679 	if (!is_ioat_halted(comp_update) && !is_ioat_suspended(comp_update))
680 		return;
681 
682 	ioat->stats.channel_halts++;
683 
684 	/*
685 	 * Fatal programming error on this DMA channel.  Flush any outstanding
686 	 * work with error status and restart the engine.
687 	 */
688 	ioat_log_message(0, "Channel halted due to fatal programming error\n");
689 	mtx_lock(&ioat->submit_lock);
690 	mtx_lock(&ioat->cleanup_lock);
691 	ioat->quiescing = TRUE;
692 
693 	chanerr = ioat_read_4(ioat, IOAT_CHANERR_OFFSET);
694 	ioat_halted_debug(ioat, chanerr);
695 	ioat->stats.last_halt_chanerr = chanerr;
696 
697 	while (ioat_get_active(ioat) > 0) {
698 		desc = ioat_get_ring_entry(ioat, ioat->tail);
699 		dmadesc = &desc->bus_dmadesc;
700 		CTR1(KTR_IOAT, "completing err desc %d", ioat->tail);
701 
702 		if (dmadesc->callback_fn != NULL)
703 			dmadesc->callback_fn(dmadesc->callback_arg,
704 			    chanerr_to_errno(chanerr));
705 
706 		ioat_putn_locked(ioat, 1, IOAT_ACTIVE_DESCR_REF);
707 		ioat->tail++;
708 		ioat->stats.descriptors_processed++;
709 		ioat->stats.descriptors_error++;
710 	}
711 
712 	/* Clear error status */
713 	ioat_write_4(ioat, IOAT_CHANERR_OFFSET, chanerr);
714 
715 	mtx_unlock(&ioat->cleanup_lock);
716 	mtx_unlock(&ioat->submit_lock);
717 
718 	ioat_log_message(0, "Resetting channel to recover from error\n");
719 	error = taskqueue_enqueue(taskqueue_thread, &ioat->reset_task);
720 	KASSERT(error == 0,
721 	    ("%s: taskqueue_enqueue failed: %d", __func__, error));
722 }
723 
724 static void
725 ioat_reset_hw_task(void *ctx, int pending __unused)
726 {
727 	struct ioat_softc *ioat;
728 	int error;
729 
730 	ioat = ctx;
731 	ioat_log_message(1, "%s: Resetting channel\n", __func__);
732 
733 	error = ioat_reset_hw(ioat);
734 	KASSERT(error == 0, ("%s: reset failed: %d", __func__, error));
735 	(void)error;
736 }
737 
738 /*
739  * User API functions
740  */
741 bus_dmaengine_t
742 ioat_get_dmaengine(uint32_t index)
743 {
744 	struct ioat_softc *sc;
745 
746 	if (index >= ioat_channel_index)
747 		return (NULL);
748 
749 	sc = ioat_channel[index];
750 	if (sc == NULL || sc->quiescing)
751 		return (NULL);
752 
753 	return (&ioat_get(sc, IOAT_DMAENGINE_REF)->dmaengine);
754 }
755 
756 void
757 ioat_put_dmaengine(bus_dmaengine_t dmaengine)
758 {
759 	struct ioat_softc *ioat;
760 
761 	ioat = to_ioat_softc(dmaengine);
762 	ioat_put(ioat, IOAT_DMAENGINE_REF);
763 }
764 
765 int
766 ioat_get_hwversion(bus_dmaengine_t dmaengine)
767 {
768 	struct ioat_softc *ioat;
769 
770 	ioat = to_ioat_softc(dmaengine);
771 	return (ioat->version);
772 }
773 
774 size_t
775 ioat_get_max_io_size(bus_dmaengine_t dmaengine)
776 {
777 	struct ioat_softc *ioat;
778 
779 	ioat = to_ioat_softc(dmaengine);
780 	return (ioat->max_xfer_size);
781 }
782 
783 int
784 ioat_set_interrupt_coalesce(bus_dmaengine_t dmaengine, uint16_t delay)
785 {
786 	struct ioat_softc *ioat;
787 
788 	ioat = to_ioat_softc(dmaengine);
789 	if (!ioat->intrdelay_supported)
790 		return (ENODEV);
791 	if (delay > ioat->intrdelay_max)
792 		return (ERANGE);
793 
794 	ioat_write_2(ioat, IOAT_INTRDELAY_OFFSET, delay);
795 	ioat->cached_intrdelay =
796 	    ioat_read_2(ioat, IOAT_INTRDELAY_OFFSET) & IOAT_INTRDELAY_US_MASK;
797 	return (0);
798 }
799 
800 uint16_t
801 ioat_get_max_coalesce_period(bus_dmaengine_t dmaengine)
802 {
803 	struct ioat_softc *ioat;
804 
805 	ioat = to_ioat_softc(dmaengine);
806 	return (ioat->intrdelay_max);
807 }
808 
809 void
810 ioat_acquire(bus_dmaengine_t dmaengine)
811 {
812 	struct ioat_softc *ioat;
813 
814 	ioat = to_ioat_softc(dmaengine);
815 	mtx_lock(&ioat->submit_lock);
816 	CTR0(KTR_IOAT, __func__);
817 }
818 
819 int
820 ioat_acquire_reserve(bus_dmaengine_t dmaengine, unsigned n, int mflags)
821 {
822 	struct ioat_softc *ioat;
823 	int error;
824 
825 	ioat = to_ioat_softc(dmaengine);
826 	ioat_acquire(dmaengine);
827 
828 	error = ioat_reserve_space(ioat, n, mflags);
829 	if (error != 0)
830 		ioat_release(dmaengine);
831 	return (error);
832 }
833 
834 void
835 ioat_release(bus_dmaengine_t dmaengine)
836 {
837 	struct ioat_softc *ioat;
838 
839 	ioat = to_ioat_softc(dmaengine);
840 	CTR0(KTR_IOAT, __func__);
841 	ioat_write_2(ioat, IOAT_DMACOUNT_OFFSET, (uint16_t)ioat->hw_head);
842 	mtx_unlock(&ioat->submit_lock);
843 }
844 
845 static struct ioat_descriptor *
846 ioat_op_generic(struct ioat_softc *ioat, uint8_t op,
847     uint32_t size, uint64_t src, uint64_t dst,
848     bus_dmaengine_callback_t callback_fn, void *callback_arg,
849     uint32_t flags)
850 {
851 	struct ioat_generic_hw_descriptor *hw_desc;
852 	struct ioat_descriptor *desc;
853 	int mflags;
854 
855 	mtx_assert(&ioat->submit_lock, MA_OWNED);
856 
857 	KASSERT((flags & ~DMA_ALL_FLAGS) == 0, ("Unrecognized flag(s): %#x",
858 		flags & ~DMA_ALL_FLAGS));
859 	if ((flags & DMA_NO_WAIT) != 0)
860 		mflags = M_NOWAIT;
861 	else
862 		mflags = M_WAITOK;
863 
864 	if (size > ioat->max_xfer_size) {
865 		ioat_log_message(0, "%s: max_xfer_size = %d, requested = %u\n",
866 		    __func__, ioat->max_xfer_size, (unsigned)size);
867 		return (NULL);
868 	}
869 
870 	if (ioat_reserve_space(ioat, 1, mflags) != 0)
871 		return (NULL);
872 
873 	desc = ioat_get_ring_entry(ioat, ioat->head);
874 	hw_desc = desc->u.generic;
875 
876 	hw_desc->u.control_raw = 0;
877 	hw_desc->u.control_generic.op = op;
878 	hw_desc->u.control_generic.completion_update = 1;
879 
880 	if ((flags & DMA_INT_EN) != 0)
881 		hw_desc->u.control_generic.int_enable = 1;
882 	if ((flags & DMA_FENCE) != 0)
883 		hw_desc->u.control_generic.fence = 1;
884 
885 	hw_desc->size = size;
886 	hw_desc->src_addr = src;
887 	hw_desc->dest_addr = dst;
888 
889 	desc->bus_dmadesc.callback_fn = callback_fn;
890 	desc->bus_dmadesc.callback_arg = callback_arg;
891 	return (desc);
892 }
893 
894 struct bus_dmadesc *
895 ioat_null(bus_dmaengine_t dmaengine, bus_dmaengine_callback_t callback_fn,
896     void *callback_arg, uint32_t flags)
897 {
898 	struct ioat_dma_hw_descriptor *hw_desc;
899 	struct ioat_descriptor *desc;
900 	struct ioat_softc *ioat;
901 
902 	CTR0(KTR_IOAT, __func__);
903 	ioat = to_ioat_softc(dmaengine);
904 
905 	desc = ioat_op_generic(ioat, IOAT_OP_COPY, 8, 0, 0, callback_fn,
906 	    callback_arg, flags);
907 	if (desc == NULL)
908 		return (NULL);
909 
910 	hw_desc = desc->u.dma;
911 	hw_desc->u.control.null = 1;
912 	ioat_submit_single(ioat);
913 	return (&desc->bus_dmadesc);
914 }
915 
916 struct bus_dmadesc *
917 ioat_copy(bus_dmaengine_t dmaengine, bus_addr_t dst,
918     bus_addr_t src, bus_size_t len, bus_dmaengine_callback_t callback_fn,
919     void *callback_arg, uint32_t flags)
920 {
921 	struct ioat_dma_hw_descriptor *hw_desc;
922 	struct ioat_descriptor *desc;
923 	struct ioat_softc *ioat;
924 
925 	CTR0(KTR_IOAT, __func__);
926 	ioat = to_ioat_softc(dmaengine);
927 
928 	if (((src | dst) & (0xffffull << 48)) != 0) {
929 		ioat_log_message(0, "%s: High 16 bits of src/dst invalid\n",
930 		    __func__);
931 		return (NULL);
932 	}
933 
934 	desc = ioat_op_generic(ioat, IOAT_OP_COPY, len, src, dst, callback_fn,
935 	    callback_arg, flags);
936 	if (desc == NULL)
937 		return (NULL);
938 
939 	hw_desc = desc->u.dma;
940 	if (g_ioat_debug_level >= 3)
941 		dump_descriptor(hw_desc);
942 
943 	ioat_submit_single(ioat);
944 	return (&desc->bus_dmadesc);
945 }
946 
947 struct bus_dmadesc *
948 ioat_copy_8k_aligned(bus_dmaengine_t dmaengine, bus_addr_t dst1,
949     bus_addr_t dst2, bus_addr_t src1, bus_addr_t src2,
950     bus_dmaengine_callback_t callback_fn, void *callback_arg, uint32_t flags)
951 {
952 	struct ioat_dma_hw_descriptor *hw_desc;
953 	struct ioat_descriptor *desc;
954 	struct ioat_softc *ioat;
955 
956 	CTR0(KTR_IOAT, __func__);
957 	ioat = to_ioat_softc(dmaengine);
958 
959 	if (((src1 | src2 | dst1 | dst2) & (0xffffull << 48)) != 0) {
960 		ioat_log_message(0, "%s: High 16 bits of src/dst invalid\n",
961 		    __func__);
962 		return (NULL);
963 	}
964 	if (((src1 | src2 | dst1 | dst2) & PAGE_MASK) != 0) {
965 		ioat_log_message(0, "%s: Addresses must be page-aligned\n",
966 		    __func__);
967 		return (NULL);
968 	}
969 
970 	desc = ioat_op_generic(ioat, IOAT_OP_COPY, 2 * PAGE_SIZE, src1, dst1,
971 	    callback_fn, callback_arg, flags);
972 	if (desc == NULL)
973 		return (NULL);
974 
975 	hw_desc = desc->u.dma;
976 	if (src2 != src1 + PAGE_SIZE) {
977 		hw_desc->u.control.src_page_break = 1;
978 		hw_desc->next_src_addr = src2;
979 	}
980 	if (dst2 != dst1 + PAGE_SIZE) {
981 		hw_desc->u.control.dest_page_break = 1;
982 		hw_desc->next_dest_addr = dst2;
983 	}
984 
985 	if (g_ioat_debug_level >= 3)
986 		dump_descriptor(hw_desc);
987 
988 	ioat_submit_single(ioat);
989 	return (&desc->bus_dmadesc);
990 }
991 
992 struct bus_dmadesc *
993 ioat_blockfill(bus_dmaengine_t dmaengine, bus_addr_t dst, uint64_t fillpattern,
994     bus_size_t len, bus_dmaengine_callback_t callback_fn, void *callback_arg,
995     uint32_t flags)
996 {
997 	struct ioat_fill_hw_descriptor *hw_desc;
998 	struct ioat_descriptor *desc;
999 	struct ioat_softc *ioat;
1000 
1001 	CTR0(KTR_IOAT, __func__);
1002 	ioat = to_ioat_softc(dmaengine);
1003 
1004 	if ((ioat->capabilities & IOAT_DMACAP_BFILL) == 0) {
1005 		ioat_log_message(0, "%s: Device lacks BFILL capability\n",
1006 		    __func__);
1007 		return (NULL);
1008 	}
1009 
1010 	if ((dst & (0xffffull << 48)) != 0) {
1011 		ioat_log_message(0, "%s: High 16 bits of dst invalid\n",
1012 		    __func__);
1013 		return (NULL);
1014 	}
1015 
1016 	desc = ioat_op_generic(ioat, IOAT_OP_FILL, len, fillpattern, dst,
1017 	    callback_fn, callback_arg, flags);
1018 	if (desc == NULL)
1019 		return (NULL);
1020 
1021 	hw_desc = desc->u.fill;
1022 	if (g_ioat_debug_level >= 3)
1023 		dump_descriptor(hw_desc);
1024 
1025 	ioat_submit_single(ioat);
1026 	return (&desc->bus_dmadesc);
1027 }
1028 
1029 /*
1030  * Ring Management
1031  */
1032 static inline uint32_t
1033 ioat_get_active(struct ioat_softc *ioat)
1034 {
1035 
1036 	return ((ioat->head - ioat->tail) & ((1 << ioat->ring_size_order) - 1));
1037 }
1038 
1039 static inline uint32_t
1040 ioat_get_ring_space(struct ioat_softc *ioat)
1041 {
1042 
1043 	return ((1 << ioat->ring_size_order) - ioat_get_active(ioat) - 1);
1044 }
1045 
1046 static struct ioat_descriptor *
1047 ioat_alloc_ring_entry(struct ioat_softc *ioat, int mflags)
1048 {
1049 	struct ioat_generic_hw_descriptor *hw_desc;
1050 	struct ioat_descriptor *desc;
1051 	int error, busdmaflag;
1052 
1053 	error = ENOMEM;
1054 	hw_desc = NULL;
1055 
1056 	if ((mflags & M_WAITOK) != 0)
1057 		busdmaflag = BUS_DMA_WAITOK;
1058 	else
1059 		busdmaflag = BUS_DMA_NOWAIT;
1060 
1061 	desc = malloc(sizeof(*desc), M_IOAT, mflags);
1062 	if (desc == NULL)
1063 		goto out;
1064 
1065 	bus_dmamem_alloc(ioat->hw_desc_tag, (void **)&hw_desc,
1066 	    BUS_DMA_ZERO | busdmaflag, &ioat->hw_desc_map);
1067 	if (hw_desc == NULL)
1068 		goto out;
1069 
1070 	memset(&desc->bus_dmadesc, 0, sizeof(desc->bus_dmadesc));
1071 	desc->u.generic = hw_desc;
1072 
1073 	error = bus_dmamap_load(ioat->hw_desc_tag, ioat->hw_desc_map, hw_desc,
1074 	    sizeof(*hw_desc), ioat_dmamap_cb, &desc->hw_desc_bus_addr,
1075 	    busdmaflag);
1076 	if (error)
1077 		goto out;
1078 
1079 out:
1080 	if (error) {
1081 		ioat_free_ring_entry(ioat, desc);
1082 		return (NULL);
1083 	}
1084 	return (desc);
1085 }
1086 
1087 static void
1088 ioat_free_ring_entry(struct ioat_softc *ioat, struct ioat_descriptor *desc)
1089 {
1090 
1091 	if (desc == NULL)
1092 		return;
1093 
1094 	if (desc->u.generic)
1095 		bus_dmamem_free(ioat->hw_desc_tag, desc->u.generic,
1096 		    ioat->hw_desc_map);
1097 	free(desc, M_IOAT);
1098 }
1099 
1100 /*
1101  * Reserves space in this IOAT descriptor ring by ensuring enough slots remain
1102  * for 'num_descs'.
1103  *
1104  * If mflags contains M_WAITOK, blocks until enough space is available.
1105  *
1106  * Returns zero on success, or an errno on error.  If num_descs is beyond the
1107  * maximum ring size, returns EINVAl; if allocation would block and mflags
1108  * contains M_NOWAIT, returns EAGAIN.
1109  *
1110  * Must be called with the submit_lock held; returns with the lock held.  The
1111  * lock may be dropped to allocate the ring.
1112  *
1113  * (The submit_lock is needed to add any entries to the ring, so callers are
1114  * assured enough room is available.)
1115  */
1116 static int
1117 ioat_reserve_space(struct ioat_softc *ioat, uint32_t num_descs, int mflags)
1118 {
1119 	struct ioat_descriptor **new_ring;
1120 	uint32_t order;
1121 	int error;
1122 
1123 	mtx_assert(&ioat->submit_lock, MA_OWNED);
1124 	error = 0;
1125 
1126 	if (num_descs < 1 || num_descs > (1 << IOAT_MAX_ORDER)) {
1127 		error = EINVAL;
1128 		goto out;
1129 	}
1130 	if (ioat->quiescing) {
1131 		error = ENXIO;
1132 		goto out;
1133 	}
1134 
1135 	for (;;) {
1136 		if (ioat_get_ring_space(ioat) >= num_descs)
1137 			goto out;
1138 
1139 		order = ioat->ring_size_order;
1140 		if (ioat->is_resize_pending || order == IOAT_MAX_ORDER) {
1141 			if ((mflags & M_WAITOK) != 0) {
1142 				msleep(&ioat->tail, &ioat->submit_lock, 0,
1143 				    "ioat_rsz", 0);
1144 				continue;
1145 			}
1146 
1147 			error = EAGAIN;
1148 			break;
1149 		}
1150 
1151 		ioat->is_resize_pending = TRUE;
1152 		for (;;) {
1153 			mtx_unlock(&ioat->submit_lock);
1154 
1155 			new_ring = ioat_prealloc_ring(ioat, 1 << (order + 1),
1156 			    TRUE, mflags);
1157 
1158 			mtx_lock(&ioat->submit_lock);
1159 			KASSERT(ioat->ring_size_order == order,
1160 			    ("is_resize_pending should protect order"));
1161 
1162 			if (new_ring == NULL) {
1163 				KASSERT((mflags & M_WAITOK) == 0,
1164 				    ("allocation failed"));
1165 				error = EAGAIN;
1166 				break;
1167 			}
1168 
1169 			error = ring_grow(ioat, order, new_ring);
1170 			if (error == 0)
1171 				break;
1172 		}
1173 		ioat->is_resize_pending = FALSE;
1174 		wakeup(&ioat->tail);
1175 		if (error)
1176 			break;
1177 	}
1178 
1179 out:
1180 	mtx_assert(&ioat->submit_lock, MA_OWNED);
1181 	return (error);
1182 }
1183 
1184 static struct ioat_descriptor **
1185 ioat_prealloc_ring(struct ioat_softc *ioat, uint32_t size, boolean_t need_dscr,
1186     int mflags)
1187 {
1188 	struct ioat_descriptor **ring;
1189 	uint32_t i;
1190 	int error;
1191 
1192 	KASSERT(size > 0 && powerof2(size), ("bogus size"));
1193 
1194 	ring = malloc(size * sizeof(*ring), M_IOAT, M_ZERO | mflags);
1195 	if (ring == NULL)
1196 		return (NULL);
1197 
1198 	if (need_dscr) {
1199 		error = ENOMEM;
1200 		for (i = size / 2; i < size; i++) {
1201 			ring[i] = ioat_alloc_ring_entry(ioat, mflags);
1202 			if (ring[i] == NULL)
1203 				goto out;
1204 			ring[i]->id = i;
1205 		}
1206 	}
1207 	error = 0;
1208 
1209 out:
1210 	if (error != 0 && ring != NULL) {
1211 		ioat_free_ring(ioat, size, ring);
1212 		ring = NULL;
1213 	}
1214 	return (ring);
1215 }
1216 
1217 static void
1218 ioat_free_ring(struct ioat_softc *ioat, uint32_t size,
1219     struct ioat_descriptor **ring)
1220 {
1221 	uint32_t i;
1222 
1223 	for (i = 0; i < size; i++) {
1224 		if (ring[i] != NULL)
1225 			ioat_free_ring_entry(ioat, ring[i]);
1226 	}
1227 	free(ring, M_IOAT);
1228 }
1229 
1230 static struct ioat_descriptor *
1231 ioat_get_ring_entry(struct ioat_softc *ioat, uint32_t index)
1232 {
1233 
1234 	return (ioat->ring[index % (1 << ioat->ring_size_order)]);
1235 }
1236 
1237 static int
1238 ring_grow(struct ioat_softc *ioat, uint32_t oldorder,
1239     struct ioat_descriptor **newring)
1240 {
1241 	struct ioat_descriptor *tmp, *next;
1242 	struct ioat_dma_hw_descriptor *hw;
1243 	uint32_t oldsize, newsize, head, tail, i, end;
1244 	int error;
1245 
1246 	CTR0(KTR_IOAT, __func__);
1247 
1248 	mtx_assert(&ioat->submit_lock, MA_OWNED);
1249 
1250 	if (oldorder != ioat->ring_size_order || oldorder >= IOAT_MAX_ORDER) {
1251 		error = EINVAL;
1252 		goto out;
1253 	}
1254 
1255 	oldsize = (1 << oldorder);
1256 	newsize = (1 << (oldorder + 1));
1257 
1258 	mtx_lock(&ioat->cleanup_lock);
1259 
1260 	head = ioat->head & (oldsize - 1);
1261 	tail = ioat->tail & (oldsize - 1);
1262 
1263 	/* Copy old descriptors to new ring */
1264 	for (i = 0; i < oldsize; i++)
1265 		newring[i] = ioat->ring[i];
1266 
1267 	/*
1268 	 * If head has wrapped but tail hasn't, we must swap some descriptors
1269 	 * around so that tail can increment directly to head.
1270 	 */
1271 	if (head < tail) {
1272 		for (i = 0; i <= head; i++) {
1273 			tmp = newring[oldsize + i];
1274 
1275 			newring[oldsize + i] = newring[i];
1276 			newring[oldsize + i]->id = oldsize + i;
1277 
1278 			newring[i] = tmp;
1279 			newring[i]->id = i;
1280 		}
1281 		head += oldsize;
1282 	}
1283 
1284 	KASSERT(head >= tail, ("invariants"));
1285 
1286 	/* Head didn't wrap; we only need to link in oldsize..newsize */
1287 	if (head < oldsize) {
1288 		i = oldsize - 1;
1289 		end = newsize;
1290 	} else {
1291 		/* Head did wrap; link newhead..newsize and 0..oldhead */
1292 		i = head;
1293 		end = newsize + (head - oldsize) + 1;
1294 	}
1295 
1296 	/*
1297 	 * Fix up hardware ring, being careful not to trample the active
1298 	 * section (tail -> head).
1299 	 */
1300 	for (; i < end; i++) {
1301 		KASSERT((i & (newsize - 1)) < tail ||
1302 		    (i & (newsize - 1)) >= head, ("trampling snake"));
1303 
1304 		next = newring[(i + 1) & (newsize - 1)];
1305 		hw = newring[i & (newsize - 1)]->u.dma;
1306 		hw->next = next->hw_desc_bus_addr;
1307 	}
1308 
1309 	free(ioat->ring, M_IOAT);
1310 	ioat->ring = newring;
1311 	ioat->ring_size_order = oldorder + 1;
1312 	ioat->tail = tail;
1313 	ioat->head = head;
1314 	error = 0;
1315 
1316 	mtx_unlock(&ioat->cleanup_lock);
1317 out:
1318 	if (error)
1319 		ioat_free_ring(ioat, (1 << (oldorder + 1)), newring);
1320 	return (error);
1321 }
1322 
1323 static int
1324 ring_shrink(struct ioat_softc *ioat, uint32_t oldorder,
1325     struct ioat_descriptor **newring)
1326 {
1327 	struct ioat_dma_hw_descriptor *hw;
1328 	struct ioat_descriptor *ent, *next;
1329 	uint32_t oldsize, newsize, current_idx, new_idx, i;
1330 	int error;
1331 
1332 	CTR0(KTR_IOAT, __func__);
1333 
1334 	mtx_assert(&ioat->submit_lock, MA_OWNED);
1335 
1336 	if (oldorder != ioat->ring_size_order || oldorder <= IOAT_MIN_ORDER) {
1337 		error = EINVAL;
1338 		goto out_unlocked;
1339 	}
1340 
1341 	oldsize = (1 << oldorder);
1342 	newsize = (1 << (oldorder - 1));
1343 
1344 	mtx_lock(&ioat->cleanup_lock);
1345 
1346 	/* Can't shrink below current active set! */
1347 	if (ioat_get_active(ioat) >= newsize) {
1348 		error = ENOMEM;
1349 		goto out;
1350 	}
1351 
1352 	/*
1353 	 * Copy current descriptors to the new ring, dropping the removed
1354 	 * descriptors.
1355 	 */
1356 	for (i = 0; i < newsize; i++) {
1357 		current_idx = (ioat->tail + i) & (oldsize - 1);
1358 		new_idx = (ioat->tail + i) & (newsize - 1);
1359 
1360 		newring[new_idx] = ioat->ring[current_idx];
1361 		newring[new_idx]->id = new_idx;
1362 	}
1363 
1364 	/* Free deleted descriptors */
1365 	for (i = newsize; i < oldsize; i++) {
1366 		ent = ioat_get_ring_entry(ioat, ioat->tail + i);
1367 		ioat_free_ring_entry(ioat, ent);
1368 	}
1369 
1370 	/* Fix up hardware ring. */
1371 	hw = newring[(ioat->tail + newsize - 1) & (newsize - 1)]->u.dma;
1372 	next = newring[(ioat->tail + newsize) & (newsize - 1)];
1373 	hw->next = next->hw_desc_bus_addr;
1374 
1375 	free(ioat->ring, M_IOAT);
1376 	ioat->ring = newring;
1377 	ioat->ring_size_order = oldorder - 1;
1378 	error = 0;
1379 
1380 out:
1381 	mtx_unlock(&ioat->cleanup_lock);
1382 out_unlocked:
1383 	if (error)
1384 		ioat_free_ring(ioat, (1 << (oldorder - 1)), newring);
1385 	return (error);
1386 }
1387 
1388 static void
1389 ioat_halted_debug(struct ioat_softc *ioat, uint32_t chanerr)
1390 {
1391 	struct ioat_descriptor *desc;
1392 
1393 	ioat_log_message(0, "Channel halted (%b)\n", (int)chanerr,
1394 	    IOAT_CHANERR_STR);
1395 	if (chanerr == 0)
1396 		return;
1397 
1398 	mtx_assert(&ioat->cleanup_lock, MA_OWNED);
1399 
1400 	desc = ioat_get_ring_entry(ioat, ioat->tail + 0);
1401 	dump_descriptor(desc->u.raw);
1402 
1403 	desc = ioat_get_ring_entry(ioat, ioat->tail + 1);
1404 	dump_descriptor(desc->u.raw);
1405 }
1406 
1407 static void
1408 ioat_timer_callback(void *arg)
1409 {
1410 	struct ioat_descriptor **newring;
1411 	struct ioat_softc *ioat;
1412 	uint32_t order;
1413 
1414 	ioat = arg;
1415 	ioat_log_message(1, "%s\n", __func__);
1416 
1417 	if (ioat->is_completion_pending) {
1418 		ioat_process_events(ioat);
1419 		return;
1420 	}
1421 
1422 	/* Slowly scale the ring down if idle. */
1423 	mtx_lock(&ioat->submit_lock);
1424 	order = ioat->ring_size_order;
1425 	if (ioat->is_resize_pending || order == IOAT_MIN_ORDER) {
1426 		mtx_unlock(&ioat->submit_lock);
1427 		goto out;
1428 	}
1429 	ioat->is_resize_pending = TRUE;
1430 	mtx_unlock(&ioat->submit_lock);
1431 
1432 	newring = ioat_prealloc_ring(ioat, 1 << (order - 1), FALSE,
1433 	    M_NOWAIT);
1434 
1435 	mtx_lock(&ioat->submit_lock);
1436 	KASSERT(ioat->ring_size_order == order,
1437 	    ("resize_pending protects order"));
1438 
1439 	if (newring != NULL)
1440 		ring_shrink(ioat, order, newring);
1441 
1442 	ioat->is_resize_pending = FALSE;
1443 	mtx_unlock(&ioat->submit_lock);
1444 
1445 out:
1446 	if (ioat->ring_size_order > IOAT_MIN_ORDER)
1447 		callout_reset(&ioat->timer, 10 * hz,
1448 		    ioat_timer_callback, ioat);
1449 }
1450 
1451 /*
1452  * Support Functions
1453  */
1454 static void
1455 ioat_submit_single(struct ioat_softc *ioat)
1456 {
1457 
1458 	ioat_get(ioat, IOAT_ACTIVE_DESCR_REF);
1459 	atomic_add_rel_int(&ioat->head, 1);
1460 	atomic_add_rel_int(&ioat->hw_head, 1);
1461 
1462 	if (!ioat->is_completion_pending) {
1463 		ioat->is_completion_pending = TRUE;
1464 		callout_reset(&ioat->timer, IOAT_INTR_TIMO,
1465 		    ioat_timer_callback, ioat);
1466 	}
1467 
1468 	ioat->stats.descriptors_submitted++;
1469 }
1470 
1471 static int
1472 ioat_reset_hw(struct ioat_softc *ioat)
1473 {
1474 	uint64_t status;
1475 	uint32_t chanerr;
1476 	unsigned timeout;
1477 	int error;
1478 
1479 	mtx_lock(IOAT_REFLK);
1480 	ioat->quiescing = TRUE;
1481 	ioat_drain_locked(ioat);
1482 	mtx_unlock(IOAT_REFLK);
1483 
1484 	status = ioat_get_chansts(ioat);
1485 	if (is_ioat_active(status) || is_ioat_idle(status))
1486 		ioat_suspend(ioat);
1487 
1488 	/* Wait at most 20 ms */
1489 	for (timeout = 0; (is_ioat_active(status) || is_ioat_idle(status)) &&
1490 	    timeout < 20; timeout++) {
1491 		DELAY(1000);
1492 		status = ioat_get_chansts(ioat);
1493 	}
1494 	if (timeout == 20) {
1495 		error = ETIMEDOUT;
1496 		goto out;
1497 	}
1498 
1499 	KASSERT(ioat_get_active(ioat) == 0, ("active after quiesce"));
1500 
1501 	chanerr = ioat_read_4(ioat, IOAT_CHANERR_OFFSET);
1502 	ioat_write_4(ioat, IOAT_CHANERR_OFFSET, chanerr);
1503 
1504 	/*
1505 	 * IOAT v3 workaround - CHANERRMSK_INT with 3E07h to masks out errors
1506 	 *  that can cause stability issues for IOAT v3.
1507 	 */
1508 	pci_write_config(ioat->device, IOAT_CFG_CHANERRMASK_INT_OFFSET, 0x3e07,
1509 	    4);
1510 	chanerr = pci_read_config(ioat->device, IOAT_CFG_CHANERR_INT_OFFSET, 4);
1511 	pci_write_config(ioat->device, IOAT_CFG_CHANERR_INT_OFFSET, chanerr, 4);
1512 
1513 	/*
1514 	 * BDXDE and BWD models reset MSI-X registers on device reset.
1515 	 * Save/restore their contents manually.
1516 	 */
1517 	if (ioat_model_resets_msix(ioat)) {
1518 		ioat_log_message(1, "device resets MSI-X registers; saving\n");
1519 		pci_save_state(ioat->device);
1520 	}
1521 
1522 	ioat_reset(ioat);
1523 
1524 	/* Wait at most 20 ms */
1525 	for (timeout = 0; ioat_reset_pending(ioat) && timeout < 20; timeout++)
1526 		DELAY(1000);
1527 	if (timeout == 20) {
1528 		error = ETIMEDOUT;
1529 		goto out;
1530 	}
1531 
1532 	if (ioat_model_resets_msix(ioat)) {
1533 		ioat_log_message(1, "device resets registers; restored\n");
1534 		pci_restore_state(ioat->device);
1535 	}
1536 
1537 	/* Reset attempts to return the hardware to "halted." */
1538 	status = ioat_get_chansts(ioat);
1539 	if (is_ioat_active(status) || is_ioat_idle(status)) {
1540 		/* So this really shouldn't happen... */
1541 		ioat_log_message(0, "Device is active after a reset?\n");
1542 		ioat_write_chanctrl(ioat, IOAT_CHANCTRL_RUN);
1543 		error = 0;
1544 		goto out;
1545 	}
1546 
1547 	chanerr = ioat_read_4(ioat, IOAT_CHANERR_OFFSET);
1548 	if (chanerr != 0) {
1549 		mtx_lock(&ioat->cleanup_lock);
1550 		ioat_halted_debug(ioat, chanerr);
1551 		mtx_unlock(&ioat->cleanup_lock);
1552 		error = EIO;
1553 		goto out;
1554 	}
1555 
1556 	/*
1557 	 * Bring device back online after reset.  Writing CHAINADDR brings the
1558 	 * device back to active.
1559 	 *
1560 	 * The internal ring counter resets to zero, so we have to start over
1561 	 * at zero as well.
1562 	 */
1563 	ioat->tail = ioat->head = ioat->hw_head = 0;
1564 	ioat->last_seen = 0;
1565 
1566 	ioat_write_chanctrl(ioat, IOAT_CHANCTRL_RUN);
1567 	ioat_write_chancmp(ioat, ioat->comp_update_bus_addr);
1568 	ioat_write_chainaddr(ioat, ioat->ring[0]->hw_desc_bus_addr);
1569 	error = 0;
1570 
1571 out:
1572 	mtx_lock(IOAT_REFLK);
1573 	ioat->quiescing = FALSE;
1574 	mtx_unlock(IOAT_REFLK);
1575 
1576 	if (error == 0)
1577 		error = ioat_start_channel(ioat);
1578 
1579 	return (error);
1580 }
1581 
1582 static int
1583 sysctl_handle_chansts(SYSCTL_HANDLER_ARGS)
1584 {
1585 	struct ioat_softc *ioat;
1586 	struct sbuf sb;
1587 	uint64_t status;
1588 	int error;
1589 
1590 	ioat = arg1;
1591 
1592 	status = ioat_get_chansts(ioat) & IOAT_CHANSTS_STATUS;
1593 
1594 	sbuf_new_for_sysctl(&sb, NULL, 256, req);
1595 	switch (status) {
1596 	case IOAT_CHANSTS_ACTIVE:
1597 		sbuf_printf(&sb, "ACTIVE");
1598 		break;
1599 	case IOAT_CHANSTS_IDLE:
1600 		sbuf_printf(&sb, "IDLE");
1601 		break;
1602 	case IOAT_CHANSTS_SUSPENDED:
1603 		sbuf_printf(&sb, "SUSPENDED");
1604 		break;
1605 	case IOAT_CHANSTS_HALTED:
1606 		sbuf_printf(&sb, "HALTED");
1607 		break;
1608 	case IOAT_CHANSTS_ARMED:
1609 		sbuf_printf(&sb, "ARMED");
1610 		break;
1611 	default:
1612 		sbuf_printf(&sb, "UNKNOWN");
1613 		break;
1614 	}
1615 	error = sbuf_finish(&sb);
1616 	sbuf_delete(&sb);
1617 
1618 	if (error != 0 || req->newptr == NULL)
1619 		return (error);
1620 	return (EINVAL);
1621 }
1622 
1623 static int
1624 sysctl_handle_dpi(SYSCTL_HANDLER_ARGS)
1625 {
1626 	struct ioat_softc *ioat;
1627 	struct sbuf sb;
1628 #define	PRECISION	"1"
1629 	const uintmax_t factor = 10;
1630 	uintmax_t rate;
1631 	int error;
1632 
1633 	ioat = arg1;
1634 	sbuf_new_for_sysctl(&sb, NULL, 16, req);
1635 
1636 	if (ioat->stats.interrupts == 0) {
1637 		sbuf_printf(&sb, "NaN");
1638 		goto out;
1639 	}
1640 	rate = ioat->stats.descriptors_processed * factor /
1641 	    ioat->stats.interrupts;
1642 	sbuf_printf(&sb, "%ju.%." PRECISION "ju", rate / factor,
1643 	    rate % factor);
1644 #undef	PRECISION
1645 out:
1646 	error = sbuf_finish(&sb);
1647 	sbuf_delete(&sb);
1648 	if (error != 0 || req->newptr == NULL)
1649 		return (error);
1650 	return (EINVAL);
1651 }
1652 
1653 static int
1654 sysctl_handle_error(SYSCTL_HANDLER_ARGS)
1655 {
1656 	struct ioat_descriptor *desc;
1657 	struct ioat_softc *ioat;
1658 	int error, arg;
1659 
1660 	ioat = arg1;
1661 
1662 	arg = 0;
1663 	error = SYSCTL_OUT(req, &arg, sizeof(arg));
1664 	if (error != 0 || req->newptr == NULL)
1665 		return (error);
1666 
1667 	error = SYSCTL_IN(req, &arg, sizeof(arg));
1668 	if (error != 0)
1669 		return (error);
1670 
1671 	if (arg != 0) {
1672 		ioat_acquire(&ioat->dmaengine);
1673 		desc = ioat_op_generic(ioat, IOAT_OP_COPY, 1,
1674 		    0xffff000000000000ull, 0xffff000000000000ull, NULL, NULL,
1675 		    0);
1676 		if (desc == NULL)
1677 			error = ENOMEM;
1678 		else
1679 			ioat_submit_single(ioat);
1680 		ioat_release(&ioat->dmaengine);
1681 	}
1682 	return (error);
1683 }
1684 
1685 static int
1686 sysctl_handle_reset(SYSCTL_HANDLER_ARGS)
1687 {
1688 	struct ioat_softc *ioat;
1689 	int error, arg;
1690 
1691 	ioat = arg1;
1692 
1693 	arg = 0;
1694 	error = SYSCTL_OUT(req, &arg, sizeof(arg));
1695 	if (error != 0 || req->newptr == NULL)
1696 		return (error);
1697 
1698 	error = SYSCTL_IN(req, &arg, sizeof(arg));
1699 	if (error != 0)
1700 		return (error);
1701 
1702 	if (arg != 0)
1703 		error = ioat_reset_hw(ioat);
1704 
1705 	return (error);
1706 }
1707 
1708 static void
1709 dump_descriptor(void *hw_desc)
1710 {
1711 	int i, j;
1712 
1713 	for (i = 0; i < 2; i++) {
1714 		for (j = 0; j < 8; j++)
1715 			printf("%08x ", ((uint32_t *)hw_desc)[i * 8 + j]);
1716 		printf("\n");
1717 	}
1718 }
1719 
1720 static void
1721 ioat_setup_sysctl(device_t device)
1722 {
1723 	struct sysctl_oid_list *par, *statpar, *state, *hammer;
1724 	struct sysctl_ctx_list *ctx;
1725 	struct sysctl_oid *tree, *tmp;
1726 	struct ioat_softc *ioat;
1727 
1728 	ioat = DEVICE2SOFTC(device);
1729 	ctx = device_get_sysctl_ctx(device);
1730 	tree = device_get_sysctl_tree(device);
1731 	par = SYSCTL_CHILDREN(tree);
1732 
1733 	SYSCTL_ADD_INT(ctx, par, OID_AUTO, "version", CTLFLAG_RD,
1734 	    &ioat->version, 0, "HW version (0xMM form)");
1735 	SYSCTL_ADD_UINT(ctx, par, OID_AUTO, "max_xfer_size", CTLFLAG_RD,
1736 	    &ioat->max_xfer_size, 0, "HW maximum transfer size");
1737 	SYSCTL_ADD_INT(ctx, par, OID_AUTO, "intrdelay_supported", CTLFLAG_RD,
1738 	    &ioat->intrdelay_supported, 0, "Is INTRDELAY supported");
1739 	SYSCTL_ADD_U16(ctx, par, OID_AUTO, "intrdelay_max", CTLFLAG_RD,
1740 	    &ioat->intrdelay_max, 0,
1741 	    "Maximum configurable INTRDELAY on this channel (microseconds)");
1742 
1743 	tmp = SYSCTL_ADD_NODE(ctx, par, OID_AUTO, "state", CTLFLAG_RD, NULL,
1744 	    "IOAT channel internal state");
1745 	state = SYSCTL_CHILDREN(tmp);
1746 
1747 	SYSCTL_ADD_UINT(ctx, state, OID_AUTO, "ring_size_order", CTLFLAG_RD,
1748 	    &ioat->ring_size_order, 0, "SW descriptor ring size order");
1749 	SYSCTL_ADD_UINT(ctx, state, OID_AUTO, "head", CTLFLAG_RD, &ioat->head,
1750 	    0, "SW descriptor head pointer index");
1751 	SYSCTL_ADD_UINT(ctx, state, OID_AUTO, "tail", CTLFLAG_RD, &ioat->tail,
1752 	    0, "SW descriptor tail pointer index");
1753 	SYSCTL_ADD_UINT(ctx, state, OID_AUTO, "hw_head", CTLFLAG_RD,
1754 	    &ioat->hw_head, 0, "HW DMACOUNT");
1755 
1756 	SYSCTL_ADD_UQUAD(ctx, state, OID_AUTO, "last_completion", CTLFLAG_RD,
1757 	    ioat->comp_update, "HW addr of last completion");
1758 
1759 	SYSCTL_ADD_INT(ctx, state, OID_AUTO, "is_resize_pending", CTLFLAG_RD,
1760 	    &ioat->is_resize_pending, 0, "resize pending");
1761 	SYSCTL_ADD_INT(ctx, state, OID_AUTO, "is_completion_pending",
1762 	    CTLFLAG_RD, &ioat->is_completion_pending, 0, "completion pending");
1763 	SYSCTL_ADD_INT(ctx, state, OID_AUTO, "is_reset_pending", CTLFLAG_RD,
1764 	    &ioat->is_reset_pending, 0, "reset pending");
1765 	SYSCTL_ADD_INT(ctx, state, OID_AUTO, "is_channel_running", CTLFLAG_RD,
1766 	    &ioat->is_channel_running, 0, "channel running");
1767 
1768 	SYSCTL_ADD_PROC(ctx, state, OID_AUTO, "chansts",
1769 	    CTLTYPE_STRING | CTLFLAG_RD, ioat, 0, sysctl_handle_chansts, "A",
1770 	    "String of the channel status");
1771 
1772 	SYSCTL_ADD_U16(ctx, state, OID_AUTO, "intrdelay", CTLFLAG_RD,
1773 	    &ioat->cached_intrdelay, 0,
1774 	    "Current INTRDELAY on this channel (cached, microseconds)");
1775 
1776 	tmp = SYSCTL_ADD_NODE(ctx, par, OID_AUTO, "hammer", CTLFLAG_RD, NULL,
1777 	    "Big hammers (mostly for testing)");
1778 	hammer = SYSCTL_CHILDREN(tmp);
1779 
1780 	SYSCTL_ADD_PROC(ctx, hammer, OID_AUTO, "force_hw_reset",
1781 	    CTLTYPE_INT | CTLFLAG_RW, ioat, 0, sysctl_handle_reset, "I",
1782 	    "Set to non-zero to reset the hardware");
1783 	SYSCTL_ADD_PROC(ctx, hammer, OID_AUTO, "force_hw_error",
1784 	    CTLTYPE_INT | CTLFLAG_RW, ioat, 0, sysctl_handle_error, "I",
1785 	    "Set to non-zero to inject a recoverable hardware error");
1786 
1787 	tmp = SYSCTL_ADD_NODE(ctx, par, OID_AUTO, "stats", CTLFLAG_RD, NULL,
1788 	    "IOAT channel statistics");
1789 	statpar = SYSCTL_CHILDREN(tmp);
1790 
1791 	SYSCTL_ADD_UQUAD(ctx, statpar, OID_AUTO, "interrupts", CTLFLAG_RW,
1792 	    &ioat->stats.interrupts,
1793 	    "Number of interrupts processed on this channel");
1794 	SYSCTL_ADD_UQUAD(ctx, statpar, OID_AUTO, "descriptors", CTLFLAG_RW,
1795 	    &ioat->stats.descriptors_processed,
1796 	    "Number of descriptors processed on this channel");
1797 	SYSCTL_ADD_UQUAD(ctx, statpar, OID_AUTO, "submitted", CTLFLAG_RW,
1798 	    &ioat->stats.descriptors_submitted,
1799 	    "Number of descriptors submitted to this channel");
1800 	SYSCTL_ADD_UQUAD(ctx, statpar, OID_AUTO, "errored", CTLFLAG_RW,
1801 	    &ioat->stats.descriptors_error,
1802 	    "Number of descriptors failed by channel errors");
1803 	SYSCTL_ADD_U32(ctx, statpar, OID_AUTO, "halts", CTLFLAG_RW,
1804 	    &ioat->stats.channel_halts, 0,
1805 	    "Number of times the channel has halted");
1806 	SYSCTL_ADD_U32(ctx, statpar, OID_AUTO, "last_halt_chanerr", CTLFLAG_RW,
1807 	    &ioat->stats.last_halt_chanerr, 0,
1808 	    "The raw CHANERR when the channel was last halted");
1809 
1810 	SYSCTL_ADD_PROC(ctx, statpar, OID_AUTO, "desc_per_interrupt",
1811 	    CTLTYPE_STRING | CTLFLAG_RD, ioat, 0, sysctl_handle_dpi, "A",
1812 	    "Descriptors per interrupt");
1813 }
1814 
1815 static inline struct ioat_softc *
1816 ioat_get(struct ioat_softc *ioat, enum ioat_ref_kind kind)
1817 {
1818 	uint32_t old;
1819 
1820 	KASSERT(kind < IOAT_NUM_REF_KINDS, ("bogus"));
1821 
1822 	old = atomic_fetchadd_32(&ioat->refcnt, 1);
1823 	KASSERT(old < UINT32_MAX, ("refcnt overflow"));
1824 
1825 #ifdef INVARIANTS
1826 	old = atomic_fetchadd_32(&ioat->refkinds[kind], 1);
1827 	KASSERT(old < UINT32_MAX, ("refcnt kind overflow"));
1828 #endif
1829 
1830 	return (ioat);
1831 }
1832 
1833 static inline void
1834 ioat_putn(struct ioat_softc *ioat, uint32_t n, enum ioat_ref_kind kind)
1835 {
1836 
1837 	_ioat_putn(ioat, n, kind, FALSE);
1838 }
1839 
1840 static inline void
1841 ioat_putn_locked(struct ioat_softc *ioat, uint32_t n, enum ioat_ref_kind kind)
1842 {
1843 
1844 	_ioat_putn(ioat, n, kind, TRUE);
1845 }
1846 
1847 static inline void
1848 _ioat_putn(struct ioat_softc *ioat, uint32_t n, enum ioat_ref_kind kind,
1849     boolean_t locked)
1850 {
1851 	uint32_t old;
1852 
1853 	KASSERT(kind < IOAT_NUM_REF_KINDS, ("bogus"));
1854 
1855 	if (n == 0)
1856 		return;
1857 
1858 #ifdef INVARIANTS
1859 	old = atomic_fetchadd_32(&ioat->refkinds[kind], -n);
1860 	KASSERT(old >= n, ("refcnt kind underflow"));
1861 #endif
1862 
1863 	/* Skip acquiring the lock if resulting refcnt > 0. */
1864 	for (;;) {
1865 		old = ioat->refcnt;
1866 		if (old <= n)
1867 			break;
1868 		if (atomic_cmpset_32(&ioat->refcnt, old, old - n))
1869 			return;
1870 	}
1871 
1872 	if (locked)
1873 		mtx_assert(IOAT_REFLK, MA_OWNED);
1874 	else
1875 		mtx_lock(IOAT_REFLK);
1876 
1877 	old = atomic_fetchadd_32(&ioat->refcnt, -n);
1878 	KASSERT(old >= n, ("refcnt error"));
1879 
1880 	if (old == n)
1881 		wakeup(IOAT_REFLK);
1882 	if (!locked)
1883 		mtx_unlock(IOAT_REFLK);
1884 }
1885 
1886 static inline void
1887 ioat_put(struct ioat_softc *ioat, enum ioat_ref_kind kind)
1888 {
1889 
1890 	ioat_putn(ioat, 1, kind);
1891 }
1892 
1893 static void
1894 ioat_drain_locked(struct ioat_softc *ioat)
1895 {
1896 
1897 	mtx_assert(IOAT_REFLK, MA_OWNED);
1898 	while (ioat->refcnt > 0)
1899 		msleep(IOAT_REFLK, IOAT_REFLK, 0, "ioat_drain", 0);
1900 }
1901