xref: /linux/arch/powerpc/platforms/pseries/msi.c (revision c02ce1735b150cf7c3b43790b48e23dcd17c0d46)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright 2006 Jake Moilanen <moilanen@austin.ibm.com>, IBM Corp.
4  * Copyright 2006-2007 Michael Ellerman, IBM Corp.
5  */
6 
7 #include <linux/crash_dump.h>
8 #include <linux/device.h>
9 #include <linux/irq.h>
10 #include <linux/irqdomain.h>
11 #include <linux/msi.h>
12 
13 #include <asm/rtas.h>
14 #include <asm/hw_irq.h>
15 #include <asm/ppc-pci.h>
16 #include <asm/machdep.h>
17 #include <asm/xive.h>
18 
19 #include "pseries.h"
20 
21 static int query_token, change_token;
22 
23 #define RTAS_QUERY_FN		0
24 #define RTAS_CHANGE_FN		1
25 #define RTAS_RESET_FN		2
26 #define RTAS_CHANGE_MSI_FN	3
27 #define RTAS_CHANGE_MSIX_FN	4
28 #define RTAS_CHANGE_32MSI_FN	5
29 #define RTAS_CHANGE_32MSIX_FN	6
30 
31 /* RTAS Helpers */
32 
33 static int rtas_change_msi(struct pci_dn *pdn, u32 func, u32 num_irqs)
34 {
35 	u32 addr, seq_num, rtas_ret[3];
36 	unsigned long buid;
37 	int rc;
38 
39 	addr = rtas_config_addr(pdn->busno, pdn->devfn, 0);
40 	buid = pdn->phb->buid;
41 
42 	seq_num = 1;
43 	do {
44 		if (func == RTAS_CHANGE_MSI_FN || func == RTAS_CHANGE_MSIX_FN ||
45 		    func == RTAS_CHANGE_32MSI_FN || func == RTAS_CHANGE_32MSIX_FN)
46 			rc = rtas_call(change_token, 6, 4, rtas_ret, addr,
47 					BUID_HI(buid), BUID_LO(buid),
48 					func, num_irqs, seq_num);
49 		else
50 			rc = rtas_call(change_token, 6, 3, rtas_ret, addr,
51 					BUID_HI(buid), BUID_LO(buid),
52 					func, num_irqs, seq_num);
53 
54 		seq_num = rtas_ret[1];
55 	} while (rtas_busy_delay(rc));
56 
57 	/*
58 	 * If the RTAS call succeeded, return the number of irqs allocated.
59 	 * If not, make sure we return a negative error code.
60 	 */
61 	if (rc == 0)
62 		rc = rtas_ret[0];
63 	else if (rc > 0)
64 		rc = -rc;
65 
66 	pr_debug("rtas_msi: ibm,change_msi(func=%d,num=%d), got %d rc = %d\n",
67 		 func, num_irqs, rtas_ret[0], rc);
68 
69 	return rc;
70 }
71 
72 static void rtas_disable_msi(struct pci_dev *pdev)
73 {
74 	struct pci_dn *pdn;
75 
76 	pdn = pci_get_pdn(pdev);
77 	if (!pdn)
78 		return;
79 
80 	/*
81 	 * disabling MSI with the explicit interface also disables MSI-X
82 	 */
83 	if (rtas_change_msi(pdn, RTAS_CHANGE_MSI_FN, 0) != 0) {
84 		/*
85 		 * may have failed because explicit interface is not
86 		 * present
87 		 */
88 		if (rtas_change_msi(pdn, RTAS_CHANGE_FN, 0) != 0) {
89 			pr_debug("rtas_msi: Setting MSIs to 0 failed!\n");
90 		}
91 	}
92 }
93 
94 static int rtas_query_irq_number(struct pci_dn *pdn, int offset)
95 {
96 	u32 addr, rtas_ret[2];
97 	unsigned long buid;
98 	int rc;
99 
100 	addr = rtas_config_addr(pdn->busno, pdn->devfn, 0);
101 	buid = pdn->phb->buid;
102 
103 	do {
104 		rc = rtas_call(query_token, 4, 3, rtas_ret, addr,
105 			       BUID_HI(buid), BUID_LO(buid), offset);
106 	} while (rtas_busy_delay(rc));
107 
108 	if (rc) {
109 		pr_debug("rtas_msi: error (%d) querying source number\n", rc);
110 		return rc;
111 	}
112 
113 	return rtas_ret[0];
114 }
115 
116 static int check_req(struct pci_dev *pdev, int nvec, char *prop_name)
117 {
118 	struct device_node *dn;
119 	const __be32 *p;
120 	u32 req_msi;
121 
122 	dn = pci_device_to_OF_node(pdev);
123 
124 	p = of_get_property(dn, prop_name, NULL);
125 	if (!p) {
126 		pr_debug("rtas_msi: No %s on %pOF\n", prop_name, dn);
127 		return -ENOENT;
128 	}
129 
130 	req_msi = be32_to_cpup(p);
131 	if (req_msi < nvec) {
132 		pr_debug("rtas_msi: %s requests < %d MSIs\n", prop_name, nvec);
133 
134 		if (req_msi == 0) /* Be paranoid */
135 			return -ENOSPC;
136 
137 		return req_msi;
138 	}
139 
140 	return 0;
141 }
142 
143 static int check_req_msi(struct pci_dev *pdev, int nvec)
144 {
145 	return check_req(pdev, nvec, "ibm,req#msi");
146 }
147 
148 static int check_req_msix(struct pci_dev *pdev, int nvec)
149 {
150 	return check_req(pdev, nvec, "ibm,req#msi-x");
151 }
152 
153 /* Quota calculation */
154 
155 static struct device_node *__find_pe_total_msi(struct device_node *node, int *total)
156 {
157 	struct device_node *dn;
158 	const __be32 *p;
159 
160 	dn = of_node_get(node);
161 	while (dn) {
162 		p = of_get_property(dn, "ibm,pe-total-#msi", NULL);
163 		if (p) {
164 			pr_debug("rtas_msi: found prop on dn %pOF\n",
165 				dn);
166 			*total = be32_to_cpup(p);
167 			return dn;
168 		}
169 
170 		dn = of_get_next_parent(dn);
171 	}
172 
173 	return NULL;
174 }
175 
176 static struct device_node *find_pe_total_msi(struct pci_dev *dev, int *total)
177 {
178 	return __find_pe_total_msi(pci_device_to_OF_node(dev), total);
179 }
180 
181 static struct device_node *find_pe_dn(struct pci_dev *dev, int *total)
182 {
183 	struct device_node *dn;
184 	struct eeh_dev *edev;
185 
186 	/* Found our PE and assume 8 at that point. */
187 
188 	dn = pci_device_to_OF_node(dev);
189 	if (!dn)
190 		return NULL;
191 
192 	/* Get the top level device in the PE */
193 	edev = pdn_to_eeh_dev(PCI_DN(dn));
194 	if (edev->pe)
195 		edev = list_first_entry(&edev->pe->edevs, struct eeh_dev,
196 					entry);
197 	dn = pci_device_to_OF_node(edev->pdev);
198 	if (!dn)
199 		return NULL;
200 
201 	/* We actually want the parent */
202 	dn = of_get_parent(dn);
203 	if (!dn)
204 		return NULL;
205 
206 	/* Hardcode of 8 for old firmwares */
207 	*total = 8;
208 	pr_debug("rtas_msi: using PE dn %pOF\n", dn);
209 
210 	return dn;
211 }
212 
213 struct msi_counts {
214 	struct device_node *requestor;
215 	int num_devices;
216 	int request;
217 	int quota;
218 	int spare;
219 	int over_quota;
220 };
221 
222 static void *count_non_bridge_devices(struct device_node *dn, void *data)
223 {
224 	struct msi_counts *counts = data;
225 	const __be32 *p;
226 	u32 class;
227 
228 	pr_debug("rtas_msi: counting %pOF\n", dn);
229 
230 	p = of_get_property(dn, "class-code", NULL);
231 	class = p ? be32_to_cpup(p) : 0;
232 
233 	if ((class >> 8) != PCI_CLASS_BRIDGE_PCI)
234 		counts->num_devices++;
235 
236 	return NULL;
237 }
238 
239 static void *count_spare_msis(struct device_node *dn, void *data)
240 {
241 	struct msi_counts *counts = data;
242 	const __be32 *p;
243 	int req;
244 
245 	if (dn == counts->requestor)
246 		req = counts->request;
247 	else {
248 		/* We don't know if a driver will try to use MSI or MSI-X,
249 		 * so we just have to punt and use the larger of the two. */
250 		req = 0;
251 		p = of_get_property(dn, "ibm,req#msi", NULL);
252 		if (p)
253 			req = be32_to_cpup(p);
254 
255 		p = of_get_property(dn, "ibm,req#msi-x", NULL);
256 		if (p)
257 			req = max(req, (int)be32_to_cpup(p));
258 	}
259 
260 	if (req < counts->quota)
261 		counts->spare += counts->quota - req;
262 	else if (req > counts->quota)
263 		counts->over_quota++;
264 
265 	return NULL;
266 }
267 
268 static int msi_quota_for_device(struct pci_dev *dev, int request)
269 {
270 	struct device_node *pe_dn;
271 	struct msi_counts counts;
272 	int total;
273 
274 	pr_debug("rtas_msi: calc quota for %s, request %d\n", pci_name(dev),
275 		  request);
276 
277 	pe_dn = find_pe_total_msi(dev, &total);
278 	if (!pe_dn)
279 		pe_dn = find_pe_dn(dev, &total);
280 
281 	if (!pe_dn) {
282 		pr_err("rtas_msi: couldn't find PE for %s\n", pci_name(dev));
283 		goto out;
284 	}
285 
286 	pr_debug("rtas_msi: found PE %pOF\n", pe_dn);
287 
288 	memset(&counts, 0, sizeof(struct msi_counts));
289 
290 	/* Work out how many devices we have below this PE */
291 	pci_traverse_device_nodes(pe_dn, count_non_bridge_devices, &counts);
292 
293 	if (counts.num_devices == 0) {
294 		pr_err("rtas_msi: found 0 devices under PE for %s\n",
295 			pci_name(dev));
296 		goto out;
297 	}
298 
299 	counts.quota = total / counts.num_devices;
300 	if (request <= counts.quota)
301 		goto out;
302 
303 	/* else, we have some more calculating to do */
304 	counts.requestor = pci_device_to_OF_node(dev);
305 	counts.request = request;
306 	pci_traverse_device_nodes(pe_dn, count_spare_msis, &counts);
307 
308 	/* If the quota isn't an integer multiple of the total, we can
309 	 * use the remainder as spare MSIs for anyone that wants them. */
310 	counts.spare += total % counts.num_devices;
311 
312 	/* Divide any spare by the number of over-quota requestors */
313 	if (counts.over_quota)
314 		counts.quota += counts.spare / counts.over_quota;
315 
316 	/* And finally clamp the request to the possibly adjusted quota */
317 	request = min(counts.quota, request);
318 
319 	pr_debug("rtas_msi: request clamped to quota %d\n", request);
320 out:
321 	of_node_put(pe_dn);
322 
323 	return request;
324 }
325 
326 static void rtas_hack_32bit_msi_gen2(struct pci_dev *pdev)
327 {
328 	u32 addr_hi, addr_lo;
329 
330 	/*
331 	 * We should only get in here for IODA1 configs. This is based on the
332 	 * fact that we using RTAS for MSIs, we don't have the 32 bit MSI RTAS
333 	 * support, and we are in a PCIe Gen2 slot.
334 	 */
335 	dev_info(&pdev->dev,
336 		 "rtas_msi: No 32 bit MSI firmware support, forcing 32 bit MSI\n");
337 	pci_read_config_dword(pdev, pdev->msi_cap + PCI_MSI_ADDRESS_HI, &addr_hi);
338 	addr_lo = 0xffff0000 | ((addr_hi >> (48 - 32)) << 4);
339 	pci_write_config_dword(pdev, pdev->msi_cap + PCI_MSI_ADDRESS_LO, addr_lo);
340 	pci_write_config_dword(pdev, pdev->msi_cap + PCI_MSI_ADDRESS_HI, 0);
341 }
342 
343 static int rtas_prepare_msi_irqs(struct pci_dev *pdev, int nvec_in, int type,
344 				 msi_alloc_info_t *arg)
345 {
346 	struct pci_dn *pdn;
347 	int quota, rc;
348 	int nvec = nvec_in;
349 	int use_32bit_msi_hack = 0;
350 
351 	if (type == PCI_CAP_ID_MSIX)
352 		rc = check_req_msix(pdev, nvec);
353 	else
354 		rc = check_req_msi(pdev, nvec);
355 
356 	if (rc)
357 		return rc;
358 
359 	quota = msi_quota_for_device(pdev, nvec);
360 
361 	if (quota && quota < nvec)
362 		return quota;
363 
364 	/*
365 	 * Firmware currently refuse any non power of two allocation
366 	 * so we round up if the quota will allow it.
367 	 */
368 	if (type == PCI_CAP_ID_MSIX) {
369 		int m = roundup_pow_of_two(nvec);
370 		quota = msi_quota_for_device(pdev, m);
371 
372 		if (quota >= m)
373 			nvec = m;
374 	}
375 
376 	pdn = pci_get_pdn(pdev);
377 
378 	/*
379 	 * Try the new more explicit firmware interface, if that fails fall
380 	 * back to the old interface. The old interface is known to never
381 	 * return MSI-Xs.
382 	 */
383 again:
384 	if (type == PCI_CAP_ID_MSI) {
385 		if (pdev->no_64bit_msi) {
386 			rc = rtas_change_msi(pdn, RTAS_CHANGE_32MSI_FN, nvec);
387 			if (rc < 0) {
388 				/*
389 				 * We only want to run the 32 bit MSI hack below if
390 				 * the max bus speed is Gen2 speed
391 				 */
392 				if (pdev->bus->max_bus_speed != PCIE_SPEED_5_0GT)
393 					return rc;
394 
395 				use_32bit_msi_hack = 1;
396 			}
397 		} else
398 			rc = -1;
399 
400 		if (rc < 0)
401 			rc = rtas_change_msi(pdn, RTAS_CHANGE_MSI_FN, nvec);
402 
403 		if (rc < 0) {
404 			pr_debug("rtas_msi: trying the old firmware call.\n");
405 			rc = rtas_change_msi(pdn, RTAS_CHANGE_FN, nvec);
406 		}
407 
408 		if (use_32bit_msi_hack && rc > 0)
409 			rtas_hack_32bit_msi_gen2(pdev);
410 	} else {
411 		if (pdev->no_64bit_msi)
412 			rc = rtas_change_msi(pdn, RTAS_CHANGE_32MSIX_FN, nvec);
413 		else
414 			rc = rtas_change_msi(pdn, RTAS_CHANGE_MSIX_FN, nvec);
415 	}
416 
417 	if (rc != nvec) {
418 		if (nvec != nvec_in) {
419 			nvec = nvec_in;
420 			goto again;
421 		}
422 		pr_debug("rtas_msi: rtas_change_msi() failed\n");
423 		return rc;
424 	}
425 
426 	return 0;
427 }
428 
429 static int pseries_msi_ops_prepare(struct irq_domain *domain, struct device *dev,
430 				   int nvec, msi_alloc_info_t *arg)
431 {
432 	struct pci_dev *pdev = to_pci_dev(dev);
433 	int type = pdev->msix_enabled ? PCI_CAP_ID_MSIX : PCI_CAP_ID_MSI;
434 
435 	return rtas_prepare_msi_irqs(pdev, nvec, type, arg);
436 }
437 
438 /*
439  * ->msi_free() is called before irq_domain_free_irqs_top() when the
440  * handler data is still available. Use that to clear the XIVE
441  * controller data.
442  */
443 static void pseries_msi_ops_msi_free(struct irq_domain *domain,
444 				     struct msi_domain_info *info,
445 				     unsigned int irq)
446 {
447 	if (xive_enabled())
448 		xive_irq_free_data(irq);
449 }
450 
451 /*
452  * RTAS can not disable one MSI at a time. It's all or nothing. Do it
453  * at the end after all IRQs have been freed.
454  */
455 static void pseries_msi_post_free(struct irq_domain *domain, struct device *dev)
456 {
457 	if (WARN_ON_ONCE(!dev_is_pci(dev)))
458 		return;
459 
460 	rtas_disable_msi(to_pci_dev(dev));
461 }
462 
463 static struct msi_domain_ops pseries_pci_msi_domain_ops = {
464 	.msi_prepare	= pseries_msi_ops_prepare,
465 	.msi_free	= pseries_msi_ops_msi_free,
466 	.msi_post_free	= pseries_msi_post_free,
467 };
468 
469 static void pseries_msi_shutdown(struct irq_data *d)
470 {
471 	d = d->parent_data;
472 	if (d->chip->irq_shutdown)
473 		d->chip->irq_shutdown(d);
474 }
475 
476 static void pseries_msi_mask(struct irq_data *d)
477 {
478 	pci_msi_mask_irq(d);
479 	irq_chip_mask_parent(d);
480 }
481 
482 static void pseries_msi_unmask(struct irq_data *d)
483 {
484 	pci_msi_unmask_irq(d);
485 	irq_chip_unmask_parent(d);
486 }
487 
488 static void pseries_msi_write_msg(struct irq_data *data, struct msi_msg *msg)
489 {
490 	struct msi_desc *entry = irq_data_get_msi_desc(data);
491 
492 	/*
493 	 * Do not update the MSIx vector table. It's not strictly necessary
494 	 * because the table is initialized by the underlying hypervisor, PowerVM
495 	 * or QEMU/KVM. However, if the MSIx vector entry is cleared, any further
496 	 * activation will fail. This can happen in some drivers (eg. IPR) which
497 	 * deactivate an IRQ used for testing MSI support.
498 	 */
499 	entry->msg = *msg;
500 }
501 
502 static struct irq_chip pseries_pci_msi_irq_chip = {
503 	.name		= "pSeries-PCI-MSI",
504 	.irq_shutdown	= pseries_msi_shutdown,
505 	.irq_mask	= pseries_msi_mask,
506 	.irq_unmask	= pseries_msi_unmask,
507 	.irq_eoi	= irq_chip_eoi_parent,
508 	.irq_write_msi_msg	= pseries_msi_write_msg,
509 };
510 
511 
512 /*
513  * Set MSI_FLAG_MSIX_CONTIGUOUS as there is no way to express to
514  * firmware to request a discontiguous or non-zero based range of
515  * MSI-X entries. Core code will reject such setup attempts.
516  */
517 static struct msi_domain_info pseries_msi_domain_info = {
518 	.flags = (MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_USE_DEF_CHIP_OPS |
519 		  MSI_FLAG_MULTI_PCI_MSI  | MSI_FLAG_PCI_MSIX |
520 		  MSI_FLAG_MSIX_CONTIGUOUS),
521 	.ops   = &pseries_pci_msi_domain_ops,
522 	.chip  = &pseries_pci_msi_irq_chip,
523 };
524 
525 static void pseries_msi_compose_msg(struct irq_data *data, struct msi_msg *msg)
526 {
527 	__pci_read_msi_msg(irq_data_get_msi_desc(data), msg);
528 }
529 
530 static struct irq_chip pseries_msi_irq_chip = {
531 	.name			= "pSeries-MSI",
532 	.irq_shutdown		= pseries_msi_shutdown,
533 	.irq_mask		= irq_chip_mask_parent,
534 	.irq_unmask		= irq_chip_unmask_parent,
535 	.irq_eoi		= irq_chip_eoi_parent,
536 	.irq_set_affinity	= irq_chip_set_affinity_parent,
537 	.irq_compose_msi_msg	= pseries_msi_compose_msg,
538 };
539 
540 static int pseries_irq_parent_domain_alloc(struct irq_domain *domain, unsigned int virq,
541 					   irq_hw_number_t hwirq)
542 {
543 	struct irq_fwspec parent_fwspec;
544 	int ret;
545 
546 	parent_fwspec.fwnode = domain->parent->fwnode;
547 	parent_fwspec.param_count = 2;
548 	parent_fwspec.param[0] = hwirq;
549 	parent_fwspec.param[1] = IRQ_TYPE_EDGE_RISING;
550 
551 	ret = irq_domain_alloc_irqs_parent(domain, virq, 1, &parent_fwspec);
552 	if (ret)
553 		return ret;
554 
555 	return 0;
556 }
557 
558 static int pseries_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
559 				    unsigned int nr_irqs, void *arg)
560 {
561 	struct pci_controller *phb = domain->host_data;
562 	msi_alloc_info_t *info = arg;
563 	struct msi_desc *desc = info->desc;
564 	struct pci_dev *pdev = msi_desc_to_pci_dev(desc);
565 	int hwirq;
566 	int i, ret;
567 
568 	hwirq = rtas_query_irq_number(pci_get_pdn(pdev), desc->msi_index);
569 	if (hwirq < 0) {
570 		dev_err(&pdev->dev, "Failed to query HW IRQ: %d\n", hwirq);
571 		return hwirq;
572 	}
573 
574 	dev_dbg(&pdev->dev, "%s bridge %pOF %d/%x #%d\n", __func__,
575 		phb->dn, virq, hwirq, nr_irqs);
576 
577 	for (i = 0; i < nr_irqs; i++) {
578 		ret = pseries_irq_parent_domain_alloc(domain, virq + i, hwirq + i);
579 		if (ret)
580 			goto out;
581 
582 		irq_domain_set_hwirq_and_chip(domain, virq + i, hwirq + i,
583 					      &pseries_msi_irq_chip, domain->host_data);
584 	}
585 
586 	return 0;
587 
588 out:
589 	/* TODO: handle RTAS cleanup in ->msi_finish() ? */
590 	irq_domain_free_irqs_parent(domain, virq, i - 1);
591 	return ret;
592 }
593 
594 static void pseries_irq_domain_free(struct irq_domain *domain, unsigned int virq,
595 				    unsigned int nr_irqs)
596 {
597 	struct irq_data *d = irq_domain_get_irq_data(domain, virq);
598 	struct pci_controller *phb = irq_data_get_irq_chip_data(d);
599 
600 	pr_debug("%s bridge %pOF %d #%d\n", __func__, phb->dn, virq, nr_irqs);
601 
602 	/* XIVE domain data is cleared through ->msi_free() */
603 }
604 
605 static const struct irq_domain_ops pseries_irq_domain_ops = {
606 	.alloc  = pseries_irq_domain_alloc,
607 	.free   = pseries_irq_domain_free,
608 };
609 
610 static int __pseries_msi_allocate_domains(struct pci_controller *phb,
611 					  unsigned int count)
612 {
613 	struct irq_domain *parent = irq_get_default_host();
614 
615 	phb->fwnode = irq_domain_alloc_named_id_fwnode("pSeries-MSI",
616 						       phb->global_number);
617 	if (!phb->fwnode)
618 		return -ENOMEM;
619 
620 	phb->dev_domain = irq_domain_create_hierarchy(parent, 0, count,
621 						      phb->fwnode,
622 						      &pseries_irq_domain_ops, phb);
623 	if (!phb->dev_domain) {
624 		pr_err("PCI: failed to create IRQ domain bridge %pOF (domain %d)\n",
625 		       phb->dn, phb->global_number);
626 		irq_domain_free_fwnode(phb->fwnode);
627 		return -ENOMEM;
628 	}
629 
630 	phb->msi_domain = pci_msi_create_irq_domain(of_node_to_fwnode(phb->dn),
631 						    &pseries_msi_domain_info,
632 						    phb->dev_domain);
633 	if (!phb->msi_domain) {
634 		pr_err("PCI: failed to create MSI IRQ domain bridge %pOF (domain %d)\n",
635 		       phb->dn, phb->global_number);
636 		irq_domain_free_fwnode(phb->fwnode);
637 		irq_domain_remove(phb->dev_domain);
638 		return -ENOMEM;
639 	}
640 
641 	return 0;
642 }
643 
644 int pseries_msi_allocate_domains(struct pci_controller *phb)
645 {
646 	int count;
647 
648 	if (!__find_pe_total_msi(phb->dn, &count)) {
649 		pr_err("PCI: failed to find MSIs for bridge %pOF (domain %d)\n",
650 		       phb->dn, phb->global_number);
651 		return -ENOSPC;
652 	}
653 
654 	return __pseries_msi_allocate_domains(phb, count);
655 }
656 
657 void pseries_msi_free_domains(struct pci_controller *phb)
658 {
659 	if (phb->msi_domain)
660 		irq_domain_remove(phb->msi_domain);
661 	if (phb->dev_domain)
662 		irq_domain_remove(phb->dev_domain);
663 	if (phb->fwnode)
664 		irq_domain_free_fwnode(phb->fwnode);
665 }
666 
667 static void rtas_msi_pci_irq_fixup(struct pci_dev *pdev)
668 {
669 	/* No LSI -> leave MSIs (if any) configured */
670 	if (!pdev->irq) {
671 		dev_dbg(&pdev->dev, "rtas_msi: no LSI, nothing to do.\n");
672 		return;
673 	}
674 
675 	/* No MSI -> MSIs can't have been assigned by fw, leave LSI */
676 	if (check_req_msi(pdev, 1) && check_req_msix(pdev, 1)) {
677 		dev_dbg(&pdev->dev, "rtas_msi: no req#msi/x, nothing to do.\n");
678 		return;
679 	}
680 
681 	dev_dbg(&pdev->dev, "rtas_msi: disabling existing MSI.\n");
682 	rtas_disable_msi(pdev);
683 }
684 
685 static int rtas_msi_init(void)
686 {
687 	query_token  = rtas_function_token(RTAS_FN_IBM_QUERY_INTERRUPT_SOURCE_NUMBER);
688 	change_token = rtas_function_token(RTAS_FN_IBM_CHANGE_MSI);
689 
690 	if ((query_token == RTAS_UNKNOWN_SERVICE) ||
691 			(change_token == RTAS_UNKNOWN_SERVICE)) {
692 		pr_debug("rtas_msi: no RTAS tokens, no MSI support.\n");
693 		return -1;
694 	}
695 
696 	pr_debug("rtas_msi: Registering RTAS MSI callbacks.\n");
697 
698 	WARN_ON(ppc_md.pci_irq_fixup);
699 	ppc_md.pci_irq_fixup = rtas_msi_pci_irq_fixup;
700 
701 	return 0;
702 }
703 machine_arch_initcall(pseries, rtas_msi_init);
704