xref: /linux/drivers/pci/doe.c (revision 7f71507851fc7764b36a3221839607d3a45c2025)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Data Object Exchange
4  *	PCIe r6.0, sec 6.30 DOE
5  *
6  * Copyright (C) 2021 Huawei
7  *	Jonathan Cameron <Jonathan.Cameron@huawei.com>
8  *
9  * Copyright (C) 2022 Intel Corporation
10  *	Ira Weiny <ira.weiny@intel.com>
11  */
12 
13 #define dev_fmt(fmt) "DOE: " fmt
14 
15 #include <linux/bitfield.h>
16 #include <linux/delay.h>
17 #include <linux/jiffies.h>
18 #include <linux/mutex.h>
19 #include <linux/pci.h>
20 #include <linux/pci-doe.h>
21 #include <linux/workqueue.h>
22 
23 #include "pci.h"
24 
25 #define PCI_DOE_PROTOCOL_DISCOVERY 0
26 
27 /* Timeout of 1 second from 6.30.2 Operation, PCI Spec r6.0 */
28 #define PCI_DOE_TIMEOUT HZ
29 #define PCI_DOE_POLL_INTERVAL	(PCI_DOE_TIMEOUT / 128)
30 
31 #define PCI_DOE_FLAG_CANCEL	0
32 #define PCI_DOE_FLAG_DEAD	1
33 
34 /* Max data object length is 2^18 dwords */
35 #define PCI_DOE_MAX_LENGTH	(1 << 18)
36 
37 /**
38  * struct pci_doe_mb - State for a single DOE mailbox
39  *
40  * This state is used to manage a single DOE mailbox capability.  All fields
41  * should be considered opaque to the consumers and the structure passed into
42  * the helpers below after being created by pci_doe_create_mb().
43  *
44  * @pdev: PCI device this mailbox belongs to
45  * @cap_offset: Capability offset
46  * @prots: Array of protocols supported (encoded as long values)
47  * @wq: Wait queue for work item
48  * @work_queue: Queue of pci_doe_work items
49  * @flags: Bit array of PCI_DOE_FLAG_* flags
50  */
51 struct pci_doe_mb {
52 	struct pci_dev *pdev;
53 	u16 cap_offset;
54 	struct xarray prots;
55 
56 	wait_queue_head_t wq;
57 	struct workqueue_struct *work_queue;
58 	unsigned long flags;
59 };
60 
61 struct pci_doe_protocol {
62 	u16 vid;
63 	u8 type;
64 };
65 
66 /**
67  * struct pci_doe_task - represents a single query/response
68  *
69  * @prot: DOE Protocol
70  * @request_pl: The request payload
71  * @request_pl_sz: Size of the request payload (bytes)
72  * @response_pl: The response payload
73  * @response_pl_sz: Size of the response payload (bytes)
74  * @rv: Return value.  Length of received response or error (bytes)
75  * @complete: Called when task is complete
76  * @private: Private data for the consumer
77  * @work: Used internally by the mailbox
78  * @doe_mb: Used internally by the mailbox
79  */
80 struct pci_doe_task {
81 	struct pci_doe_protocol prot;
82 	const __le32 *request_pl;
83 	size_t request_pl_sz;
84 	__le32 *response_pl;
85 	size_t response_pl_sz;
86 	int rv;
87 	void (*complete)(struct pci_doe_task *task);
88 	void *private;
89 
90 	/* initialized by pci_doe_submit_task() */
91 	struct work_struct work;
92 	struct pci_doe_mb *doe_mb;
93 };
94 
95 static int pci_doe_wait(struct pci_doe_mb *doe_mb, unsigned long timeout)
96 {
97 	if (wait_event_timeout(doe_mb->wq,
98 			       test_bit(PCI_DOE_FLAG_CANCEL, &doe_mb->flags),
99 			       timeout))
100 		return -EIO;
101 	return 0;
102 }
103 
104 static void pci_doe_write_ctrl(struct pci_doe_mb *doe_mb, u32 val)
105 {
106 	struct pci_dev *pdev = doe_mb->pdev;
107 	int offset = doe_mb->cap_offset;
108 
109 	pci_write_config_dword(pdev, offset + PCI_DOE_CTRL, val);
110 }
111 
112 static int pci_doe_abort(struct pci_doe_mb *doe_mb)
113 {
114 	struct pci_dev *pdev = doe_mb->pdev;
115 	int offset = doe_mb->cap_offset;
116 	unsigned long timeout_jiffies;
117 
118 	pci_dbg(pdev, "[%x] Issuing Abort\n", offset);
119 
120 	timeout_jiffies = jiffies + PCI_DOE_TIMEOUT;
121 	pci_doe_write_ctrl(doe_mb, PCI_DOE_CTRL_ABORT);
122 
123 	do {
124 		int rc;
125 		u32 val;
126 
127 		rc = pci_doe_wait(doe_mb, PCI_DOE_POLL_INTERVAL);
128 		if (rc)
129 			return rc;
130 		pci_read_config_dword(pdev, offset + PCI_DOE_STATUS, &val);
131 
132 		/* Abort success! */
133 		if (!FIELD_GET(PCI_DOE_STATUS_ERROR, val) &&
134 		    !FIELD_GET(PCI_DOE_STATUS_BUSY, val))
135 			return 0;
136 
137 	} while (!time_after(jiffies, timeout_jiffies));
138 
139 	/* Abort has timed out and the MB is dead */
140 	pci_err(pdev, "[%x] ABORT timed out\n", offset);
141 	return -EIO;
142 }
143 
144 static int pci_doe_send_req(struct pci_doe_mb *doe_mb,
145 			    struct pci_doe_task *task)
146 {
147 	struct pci_dev *pdev = doe_mb->pdev;
148 	int offset = doe_mb->cap_offset;
149 	unsigned long timeout_jiffies;
150 	size_t length, remainder;
151 	u32 val;
152 	int i;
153 
154 	/*
155 	 * Check the DOE busy bit is not set. If it is set, this could indicate
156 	 * someone other than Linux (e.g. firmware) is using the mailbox. Note
157 	 * it is expected that firmware and OS will negotiate access rights via
158 	 * an, as yet to be defined, method.
159 	 *
160 	 * Wait up to one PCI_DOE_TIMEOUT period to allow the prior command to
161 	 * finish. Otherwise, simply error out as unable to field the request.
162 	 *
163 	 * PCIe r6.2 sec 6.30.3 states no interrupt is raised when the DOE Busy
164 	 * bit is cleared, so polling here is our best option for the moment.
165 	 */
166 	timeout_jiffies = jiffies + PCI_DOE_TIMEOUT;
167 	do {
168 		pci_read_config_dword(pdev, offset + PCI_DOE_STATUS, &val);
169 	} while (FIELD_GET(PCI_DOE_STATUS_BUSY, val) &&
170 		 !time_after(jiffies, timeout_jiffies));
171 
172 	if (FIELD_GET(PCI_DOE_STATUS_BUSY, val))
173 		return -EBUSY;
174 
175 	if (FIELD_GET(PCI_DOE_STATUS_ERROR, val))
176 		return -EIO;
177 
178 	/* Length is 2 DW of header + length of payload in DW */
179 	length = 2 + DIV_ROUND_UP(task->request_pl_sz, sizeof(__le32));
180 	if (length > PCI_DOE_MAX_LENGTH)
181 		return -EIO;
182 	if (length == PCI_DOE_MAX_LENGTH)
183 		length = 0;
184 
185 	/* Write DOE Header */
186 	val = FIELD_PREP(PCI_DOE_DATA_OBJECT_HEADER_1_VID, task->prot.vid) |
187 		FIELD_PREP(PCI_DOE_DATA_OBJECT_HEADER_1_TYPE, task->prot.type);
188 	pci_write_config_dword(pdev, offset + PCI_DOE_WRITE, val);
189 	pci_write_config_dword(pdev, offset + PCI_DOE_WRITE,
190 			       FIELD_PREP(PCI_DOE_DATA_OBJECT_HEADER_2_LENGTH,
191 					  length));
192 
193 	/* Write payload */
194 	for (i = 0; i < task->request_pl_sz / sizeof(__le32); i++)
195 		pci_write_config_dword(pdev, offset + PCI_DOE_WRITE,
196 				       le32_to_cpu(task->request_pl[i]));
197 
198 	/* Write last payload dword */
199 	remainder = task->request_pl_sz % sizeof(__le32);
200 	if (remainder) {
201 		val = 0;
202 		memcpy(&val, &task->request_pl[i], remainder);
203 		le32_to_cpus(&val);
204 		pci_write_config_dword(pdev, offset + PCI_DOE_WRITE, val);
205 	}
206 
207 	pci_doe_write_ctrl(doe_mb, PCI_DOE_CTRL_GO);
208 
209 	return 0;
210 }
211 
212 static bool pci_doe_data_obj_ready(struct pci_doe_mb *doe_mb)
213 {
214 	struct pci_dev *pdev = doe_mb->pdev;
215 	int offset = doe_mb->cap_offset;
216 	u32 val;
217 
218 	pci_read_config_dword(pdev, offset + PCI_DOE_STATUS, &val);
219 	if (FIELD_GET(PCI_DOE_STATUS_DATA_OBJECT_READY, val))
220 		return true;
221 	return false;
222 }
223 
224 static int pci_doe_recv_resp(struct pci_doe_mb *doe_mb, struct pci_doe_task *task)
225 {
226 	size_t length, payload_length, remainder, received;
227 	struct pci_dev *pdev = doe_mb->pdev;
228 	int offset = doe_mb->cap_offset;
229 	int i = 0;
230 	u32 val;
231 
232 	/* Read the first dword to get the protocol */
233 	pci_read_config_dword(pdev, offset + PCI_DOE_READ, &val);
234 	if ((FIELD_GET(PCI_DOE_DATA_OBJECT_HEADER_1_VID, val) != task->prot.vid) ||
235 	    (FIELD_GET(PCI_DOE_DATA_OBJECT_HEADER_1_TYPE, val) != task->prot.type)) {
236 		dev_err_ratelimited(&pdev->dev, "[%x] expected [VID, Protocol] = [%04x, %02x], got [%04x, %02x]\n",
237 				    doe_mb->cap_offset, task->prot.vid, task->prot.type,
238 				    FIELD_GET(PCI_DOE_DATA_OBJECT_HEADER_1_VID, val),
239 				    FIELD_GET(PCI_DOE_DATA_OBJECT_HEADER_1_TYPE, val));
240 		return -EIO;
241 	}
242 
243 	pci_write_config_dword(pdev, offset + PCI_DOE_READ, 0);
244 	/* Read the second dword to get the length */
245 	pci_read_config_dword(pdev, offset + PCI_DOE_READ, &val);
246 	pci_write_config_dword(pdev, offset + PCI_DOE_READ, 0);
247 
248 	length = FIELD_GET(PCI_DOE_DATA_OBJECT_HEADER_2_LENGTH, val);
249 	/* A value of 0x0 indicates max data object length */
250 	if (!length)
251 		length = PCI_DOE_MAX_LENGTH;
252 	if (length < 2)
253 		return -EIO;
254 
255 	/* First 2 dwords have already been read */
256 	length -= 2;
257 	received = task->response_pl_sz;
258 	payload_length = DIV_ROUND_UP(task->response_pl_sz, sizeof(__le32));
259 	remainder = task->response_pl_sz % sizeof(__le32);
260 
261 	/* remainder signifies number of data bytes in last payload dword */
262 	if (!remainder)
263 		remainder = sizeof(__le32);
264 
265 	if (length < payload_length) {
266 		received = length * sizeof(__le32);
267 		payload_length = length;
268 		remainder = sizeof(__le32);
269 	}
270 
271 	if (payload_length) {
272 		/* Read all payload dwords except the last */
273 		for (; i < payload_length - 1; i++) {
274 			pci_read_config_dword(pdev, offset + PCI_DOE_READ,
275 					      &val);
276 			task->response_pl[i] = cpu_to_le32(val);
277 			pci_write_config_dword(pdev, offset + PCI_DOE_READ, 0);
278 		}
279 
280 		/* Read last payload dword */
281 		pci_read_config_dword(pdev, offset + PCI_DOE_READ, &val);
282 		cpu_to_le32s(&val);
283 		memcpy(&task->response_pl[i], &val, remainder);
284 		/* Prior to the last ack, ensure Data Object Ready */
285 		if (!pci_doe_data_obj_ready(doe_mb))
286 			return -EIO;
287 		pci_write_config_dword(pdev, offset + PCI_DOE_READ, 0);
288 		i++;
289 	}
290 
291 	/* Flush excess length */
292 	for (; i < length; i++) {
293 		pci_read_config_dword(pdev, offset + PCI_DOE_READ, &val);
294 		pci_write_config_dword(pdev, offset + PCI_DOE_READ, 0);
295 	}
296 
297 	/* Final error check to pick up on any since Data Object Ready */
298 	pci_read_config_dword(pdev, offset + PCI_DOE_STATUS, &val);
299 	if (FIELD_GET(PCI_DOE_STATUS_ERROR, val))
300 		return -EIO;
301 
302 	return received;
303 }
304 
305 static void signal_task_complete(struct pci_doe_task *task, int rv)
306 {
307 	task->rv = rv;
308 	destroy_work_on_stack(&task->work);
309 	task->complete(task);
310 }
311 
312 static void signal_task_abort(struct pci_doe_task *task, int rv)
313 {
314 	struct pci_doe_mb *doe_mb = task->doe_mb;
315 	struct pci_dev *pdev = doe_mb->pdev;
316 
317 	if (pci_doe_abort(doe_mb)) {
318 		/*
319 		 * If the device can't process an abort; set the mailbox dead
320 		 *	- no more submissions
321 		 */
322 		pci_err(pdev, "[%x] Abort failed marking mailbox dead\n",
323 			doe_mb->cap_offset);
324 		set_bit(PCI_DOE_FLAG_DEAD, &doe_mb->flags);
325 	}
326 	signal_task_complete(task, rv);
327 }
328 
329 static void doe_statemachine_work(struct work_struct *work)
330 {
331 	struct pci_doe_task *task = container_of(work, struct pci_doe_task,
332 						 work);
333 	struct pci_doe_mb *doe_mb = task->doe_mb;
334 	struct pci_dev *pdev = doe_mb->pdev;
335 	int offset = doe_mb->cap_offset;
336 	unsigned long timeout_jiffies;
337 	u32 val;
338 	int rc;
339 
340 	if (test_bit(PCI_DOE_FLAG_DEAD, &doe_mb->flags)) {
341 		signal_task_complete(task, -EIO);
342 		return;
343 	}
344 
345 	/* Send request */
346 	rc = pci_doe_send_req(doe_mb, task);
347 	if (rc) {
348 		/*
349 		 * The specification does not provide any guidance on how to
350 		 * resolve conflicting requests from other entities.
351 		 * Furthermore, it is likely that busy will not be detected
352 		 * most of the time.  Flag any detection of status busy with an
353 		 * error.
354 		 */
355 		if (rc == -EBUSY)
356 			dev_err_ratelimited(&pdev->dev, "[%x] busy detected; another entity is sending conflicting requests\n",
357 					    offset);
358 		signal_task_abort(task, rc);
359 		return;
360 	}
361 
362 	timeout_jiffies = jiffies + PCI_DOE_TIMEOUT;
363 	/* Poll for response */
364 retry_resp:
365 	pci_read_config_dword(pdev, offset + PCI_DOE_STATUS, &val);
366 	if (FIELD_GET(PCI_DOE_STATUS_ERROR, val)) {
367 		signal_task_abort(task, -EIO);
368 		return;
369 	}
370 
371 	if (!FIELD_GET(PCI_DOE_STATUS_DATA_OBJECT_READY, val)) {
372 		if (time_after(jiffies, timeout_jiffies)) {
373 			signal_task_abort(task, -EIO);
374 			return;
375 		}
376 		rc = pci_doe_wait(doe_mb, PCI_DOE_POLL_INTERVAL);
377 		if (rc) {
378 			signal_task_abort(task, rc);
379 			return;
380 		}
381 		goto retry_resp;
382 	}
383 
384 	rc  = pci_doe_recv_resp(doe_mb, task);
385 	if (rc < 0) {
386 		signal_task_abort(task, rc);
387 		return;
388 	}
389 
390 	signal_task_complete(task, rc);
391 }
392 
393 static void pci_doe_task_complete(struct pci_doe_task *task)
394 {
395 	complete(task->private);
396 }
397 
398 static int pci_doe_discovery(struct pci_doe_mb *doe_mb, u8 capver, u8 *index, u16 *vid,
399 			     u8 *protocol)
400 {
401 	u32 request_pl = FIELD_PREP(PCI_DOE_DATA_OBJECT_DISC_REQ_3_INDEX,
402 				    *index) |
403 			 FIELD_PREP(PCI_DOE_DATA_OBJECT_DISC_REQ_3_VER,
404 				    (capver >= 2) ? 2 : 0);
405 	__le32 request_pl_le = cpu_to_le32(request_pl);
406 	__le32 response_pl_le;
407 	u32 response_pl;
408 	int rc;
409 
410 	rc = pci_doe(doe_mb, PCI_VENDOR_ID_PCI_SIG, PCI_DOE_PROTOCOL_DISCOVERY,
411 		     &request_pl_le, sizeof(request_pl_le),
412 		     &response_pl_le, sizeof(response_pl_le));
413 	if (rc < 0)
414 		return rc;
415 
416 	if (rc != sizeof(response_pl_le))
417 		return -EIO;
418 
419 	response_pl = le32_to_cpu(response_pl_le);
420 	*vid = FIELD_GET(PCI_DOE_DATA_OBJECT_DISC_RSP_3_VID, response_pl);
421 	*protocol = FIELD_GET(PCI_DOE_DATA_OBJECT_DISC_RSP_3_PROTOCOL,
422 			      response_pl);
423 	*index = FIELD_GET(PCI_DOE_DATA_OBJECT_DISC_RSP_3_NEXT_INDEX,
424 			   response_pl);
425 
426 	return 0;
427 }
428 
429 static void *pci_doe_xa_prot_entry(u16 vid, u8 prot)
430 {
431 	return xa_mk_value((vid << 8) | prot);
432 }
433 
434 static int pci_doe_cache_protocols(struct pci_doe_mb *doe_mb)
435 {
436 	u8 index = 0;
437 	u8 xa_idx = 0;
438 	u32 hdr = 0;
439 
440 	pci_read_config_dword(doe_mb->pdev, doe_mb->cap_offset, &hdr);
441 
442 	do {
443 		int rc;
444 		u16 vid;
445 		u8 prot;
446 
447 		rc = pci_doe_discovery(doe_mb, PCI_EXT_CAP_VER(hdr), &index,
448 				       &vid, &prot);
449 		if (rc)
450 			return rc;
451 
452 		pci_dbg(doe_mb->pdev,
453 			"[%x] Found protocol %d vid: %x prot: %x\n",
454 			doe_mb->cap_offset, xa_idx, vid, prot);
455 
456 		rc = xa_insert(&doe_mb->prots, xa_idx++,
457 			       pci_doe_xa_prot_entry(vid, prot), GFP_KERNEL);
458 		if (rc)
459 			return rc;
460 	} while (index);
461 
462 	return 0;
463 }
464 
465 static void pci_doe_cancel_tasks(struct pci_doe_mb *doe_mb)
466 {
467 	/* Stop all pending work items from starting */
468 	set_bit(PCI_DOE_FLAG_DEAD, &doe_mb->flags);
469 
470 	/* Cancel an in progress work item, if necessary */
471 	set_bit(PCI_DOE_FLAG_CANCEL, &doe_mb->flags);
472 	wake_up(&doe_mb->wq);
473 }
474 
475 /**
476  * pci_doe_create_mb() - Create a DOE mailbox object
477  *
478  * @pdev: PCI device to create the DOE mailbox for
479  * @cap_offset: Offset of the DOE mailbox
480  *
481  * Create a single mailbox object to manage the mailbox protocol at the
482  * cap_offset specified.
483  *
484  * RETURNS: created mailbox object on success
485  *	    ERR_PTR(-errno) on failure
486  */
487 static struct pci_doe_mb *pci_doe_create_mb(struct pci_dev *pdev,
488 					    u16 cap_offset)
489 {
490 	struct pci_doe_mb *doe_mb;
491 	int rc;
492 
493 	doe_mb = kzalloc(sizeof(*doe_mb), GFP_KERNEL);
494 	if (!doe_mb)
495 		return ERR_PTR(-ENOMEM);
496 
497 	doe_mb->pdev = pdev;
498 	doe_mb->cap_offset = cap_offset;
499 	init_waitqueue_head(&doe_mb->wq);
500 	xa_init(&doe_mb->prots);
501 
502 	doe_mb->work_queue = alloc_ordered_workqueue("%s %s DOE [%x]", 0,
503 						dev_bus_name(&pdev->dev),
504 						pci_name(pdev),
505 						doe_mb->cap_offset);
506 	if (!doe_mb->work_queue) {
507 		pci_err(pdev, "[%x] failed to allocate work queue\n",
508 			doe_mb->cap_offset);
509 		rc = -ENOMEM;
510 		goto err_free;
511 	}
512 
513 	/* Reset the mailbox by issuing an abort */
514 	rc = pci_doe_abort(doe_mb);
515 	if (rc) {
516 		pci_err(pdev, "[%x] failed to reset mailbox with abort command : %d\n",
517 			doe_mb->cap_offset, rc);
518 		goto err_destroy_wq;
519 	}
520 
521 	/*
522 	 * The state machine and the mailbox should be in sync now;
523 	 * Use the mailbox to query protocols.
524 	 */
525 	rc = pci_doe_cache_protocols(doe_mb);
526 	if (rc) {
527 		pci_err(pdev, "[%x] failed to cache protocols : %d\n",
528 			doe_mb->cap_offset, rc);
529 		goto err_cancel;
530 	}
531 
532 	return doe_mb;
533 
534 err_cancel:
535 	pci_doe_cancel_tasks(doe_mb);
536 	xa_destroy(&doe_mb->prots);
537 err_destroy_wq:
538 	destroy_workqueue(doe_mb->work_queue);
539 err_free:
540 	kfree(doe_mb);
541 	return ERR_PTR(rc);
542 }
543 
544 /**
545  * pci_doe_destroy_mb() - Destroy a DOE mailbox object
546  *
547  * @doe_mb: DOE mailbox
548  *
549  * Destroy all internal data structures created for the DOE mailbox.
550  */
551 static void pci_doe_destroy_mb(struct pci_doe_mb *doe_mb)
552 {
553 	pci_doe_cancel_tasks(doe_mb);
554 	xa_destroy(&doe_mb->prots);
555 	destroy_workqueue(doe_mb->work_queue);
556 	kfree(doe_mb);
557 }
558 
559 /**
560  * pci_doe_supports_prot() - Return if the DOE instance supports the given
561  *			     protocol
562  * @doe_mb: DOE mailbox capability to query
563  * @vid: Protocol Vendor ID
564  * @type: Protocol type
565  *
566  * RETURNS: True if the DOE mailbox supports the protocol specified
567  */
568 static bool pci_doe_supports_prot(struct pci_doe_mb *doe_mb, u16 vid, u8 type)
569 {
570 	unsigned long index;
571 	void *entry;
572 
573 	/* The discovery protocol must always be supported */
574 	if (vid == PCI_VENDOR_ID_PCI_SIG && type == PCI_DOE_PROTOCOL_DISCOVERY)
575 		return true;
576 
577 	xa_for_each(&doe_mb->prots, index, entry)
578 		if (entry == pci_doe_xa_prot_entry(vid, type))
579 			return true;
580 
581 	return false;
582 }
583 
584 /**
585  * pci_doe_submit_task() - Submit a task to be processed by the state machine
586  *
587  * @doe_mb: DOE mailbox capability to submit to
588  * @task: task to be queued
589  *
590  * Submit a DOE task (request/response) to the DOE mailbox to be processed.
591  * Returns upon queueing the task object.  If the queue is full this function
592  * will sleep until there is room in the queue.
593  *
594  * task->complete will be called when the state machine is done processing this
595  * task.
596  *
597  * @task must be allocated on the stack.
598  *
599  * Excess data will be discarded.
600  *
601  * RETURNS: 0 when task has been successfully queued, -ERRNO on error
602  */
603 static int pci_doe_submit_task(struct pci_doe_mb *doe_mb,
604 			       struct pci_doe_task *task)
605 {
606 	if (!pci_doe_supports_prot(doe_mb, task->prot.vid, task->prot.type))
607 		return -EINVAL;
608 
609 	if (test_bit(PCI_DOE_FLAG_DEAD, &doe_mb->flags))
610 		return -EIO;
611 
612 	task->doe_mb = doe_mb;
613 	INIT_WORK_ONSTACK(&task->work, doe_statemachine_work);
614 	queue_work(doe_mb->work_queue, &task->work);
615 	return 0;
616 }
617 
618 /**
619  * pci_doe() - Perform Data Object Exchange
620  *
621  * @doe_mb: DOE Mailbox
622  * @vendor: Vendor ID
623  * @type: Data Object Type
624  * @request: Request payload
625  * @request_sz: Size of request payload (bytes)
626  * @response: Response payload
627  * @response_sz: Size of response payload (bytes)
628  *
629  * Submit @request to @doe_mb and store the @response.
630  * The DOE exchange is performed synchronously and may therefore sleep.
631  *
632  * Payloads are treated as opaque byte streams which are transmitted verbatim,
633  * without byte-swapping.  If payloads contain little-endian register values,
634  * the caller is responsible for conversion with cpu_to_le32() / le32_to_cpu().
635  *
636  * For convenience, arbitrary payload sizes are allowed even though PCIe r6.0
637  * sec 6.30.1 specifies the Data Object Header 2 "Length" in dwords.  The last
638  * (partial) dword is copied with byte granularity and padded with zeroes if
639  * necessary.  Callers are thus relieved of using dword-sized bounce buffers.
640  *
641  * RETURNS: Length of received response or negative errno.
642  * Received data in excess of @response_sz is discarded.
643  * The length may be smaller than @response_sz and the caller
644  * is responsible for checking that.
645  */
646 int pci_doe(struct pci_doe_mb *doe_mb, u16 vendor, u8 type,
647 	    const void *request, size_t request_sz,
648 	    void *response, size_t response_sz)
649 {
650 	DECLARE_COMPLETION_ONSTACK(c);
651 	struct pci_doe_task task = {
652 		.prot.vid = vendor,
653 		.prot.type = type,
654 		.request_pl = request,
655 		.request_pl_sz = request_sz,
656 		.response_pl = response,
657 		.response_pl_sz = response_sz,
658 		.complete = pci_doe_task_complete,
659 		.private = &c,
660 	};
661 	int rc;
662 
663 	rc = pci_doe_submit_task(doe_mb, &task);
664 	if (rc)
665 		return rc;
666 
667 	wait_for_completion(&c);
668 
669 	return task.rv;
670 }
671 EXPORT_SYMBOL_GPL(pci_doe);
672 
673 /**
674  * pci_find_doe_mailbox() - Find Data Object Exchange mailbox
675  *
676  * @pdev: PCI device
677  * @vendor: Vendor ID
678  * @type: Data Object Type
679  *
680  * Find first DOE mailbox of a PCI device which supports the given protocol.
681  *
682  * RETURNS: Pointer to the DOE mailbox or NULL if none was found.
683  */
684 struct pci_doe_mb *pci_find_doe_mailbox(struct pci_dev *pdev, u16 vendor,
685 					u8 type)
686 {
687 	struct pci_doe_mb *doe_mb;
688 	unsigned long index;
689 
690 	xa_for_each(&pdev->doe_mbs, index, doe_mb)
691 		if (pci_doe_supports_prot(doe_mb, vendor, type))
692 			return doe_mb;
693 
694 	return NULL;
695 }
696 EXPORT_SYMBOL_GPL(pci_find_doe_mailbox);
697 
698 void pci_doe_init(struct pci_dev *pdev)
699 {
700 	struct pci_doe_mb *doe_mb;
701 	u16 offset = 0;
702 	int rc;
703 
704 	xa_init(&pdev->doe_mbs);
705 
706 	while ((offset = pci_find_next_ext_capability(pdev, offset,
707 						      PCI_EXT_CAP_ID_DOE))) {
708 		doe_mb = pci_doe_create_mb(pdev, offset);
709 		if (IS_ERR(doe_mb)) {
710 			pci_err(pdev, "[%x] failed to create mailbox: %ld\n",
711 				offset, PTR_ERR(doe_mb));
712 			continue;
713 		}
714 
715 		rc = xa_insert(&pdev->doe_mbs, offset, doe_mb, GFP_KERNEL);
716 		if (rc) {
717 			pci_err(pdev, "[%x] failed to insert mailbox: %d\n",
718 				offset, rc);
719 			pci_doe_destroy_mb(doe_mb);
720 		}
721 	}
722 }
723 
724 void pci_doe_destroy(struct pci_dev *pdev)
725 {
726 	struct pci_doe_mb *doe_mb;
727 	unsigned long index;
728 
729 	xa_for_each(&pdev->doe_mbs, index, doe_mb)
730 		pci_doe_destroy_mb(doe_mb);
731 
732 	xa_destroy(&pdev->doe_mbs);
733 }
734 
735 void pci_doe_disconnected(struct pci_dev *pdev)
736 {
737 	struct pci_doe_mb *doe_mb;
738 	unsigned long index;
739 
740 	xa_for_each(&pdev->doe_mbs, index, doe_mb)
741 		pci_doe_cancel_tasks(doe_mb);
742 }
743