xref: /linux/arch/powerpc/sysdev/xive/spapr.c (revision 37744feebc086908fd89760650f458ab19071750)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Copyright 2016,2017 IBM Corporation.
4  */
5 
6 #define pr_fmt(fmt) "xive: " fmt
7 
8 #include <linux/types.h>
9 #include <linux/irq.h>
10 #include <linux/smp.h>
11 #include <linux/interrupt.h>
12 #include <linux/init.h>
13 #include <linux/of.h>
14 #include <linux/slab.h>
15 #include <linux/spinlock.h>
16 #include <linux/cpumask.h>
17 #include <linux/mm.h>
18 #include <linux/delay.h>
19 #include <linux/libfdt.h>
20 
21 #include <asm/machdep.h>
22 #include <asm/prom.h>
23 #include <asm/io.h>
24 #include <asm/smp.h>
25 #include <asm/irq.h>
26 #include <asm/errno.h>
27 #include <asm/xive.h>
28 #include <asm/xive-regs.h>
29 #include <asm/hvcall.h>
30 
31 #include "xive-internal.h"
32 
33 static u32 xive_queue_shift;
34 
35 struct xive_irq_bitmap {
36 	unsigned long		*bitmap;
37 	unsigned int		base;
38 	unsigned int		count;
39 	spinlock_t		lock;
40 	struct list_head	list;
41 };
42 
43 static LIST_HEAD(xive_irq_bitmaps);
44 
45 static int xive_irq_bitmap_add(int base, int count)
46 {
47 	struct xive_irq_bitmap *xibm;
48 
49 	xibm = kzalloc(sizeof(*xibm), GFP_KERNEL);
50 	if (!xibm)
51 		return -ENOMEM;
52 
53 	spin_lock_init(&xibm->lock);
54 	xibm->base = base;
55 	xibm->count = count;
56 	xibm->bitmap = kzalloc(xibm->count, GFP_KERNEL);
57 	if (!xibm->bitmap) {
58 		kfree(xibm);
59 		return -ENOMEM;
60 	}
61 	list_add(&xibm->list, &xive_irq_bitmaps);
62 
63 	pr_info("Using IRQ range [%x-%x]", xibm->base,
64 		xibm->base + xibm->count - 1);
65 	return 0;
66 }
67 
68 static int __xive_irq_bitmap_alloc(struct xive_irq_bitmap *xibm)
69 {
70 	int irq;
71 
72 	irq = find_first_zero_bit(xibm->bitmap, xibm->count);
73 	if (irq != xibm->count) {
74 		set_bit(irq, xibm->bitmap);
75 		irq += xibm->base;
76 	} else {
77 		irq = -ENOMEM;
78 	}
79 
80 	return irq;
81 }
82 
83 static int xive_irq_bitmap_alloc(void)
84 {
85 	struct xive_irq_bitmap *xibm;
86 	unsigned long flags;
87 	int irq = -ENOENT;
88 
89 	list_for_each_entry(xibm, &xive_irq_bitmaps, list) {
90 		spin_lock_irqsave(&xibm->lock, flags);
91 		irq = __xive_irq_bitmap_alloc(xibm);
92 		spin_unlock_irqrestore(&xibm->lock, flags);
93 		if (irq >= 0)
94 			break;
95 	}
96 	return irq;
97 }
98 
99 static void xive_irq_bitmap_free(int irq)
100 {
101 	unsigned long flags;
102 	struct xive_irq_bitmap *xibm;
103 
104 	list_for_each_entry(xibm, &xive_irq_bitmaps, list) {
105 		if ((irq >= xibm->base) && (irq < xibm->base + xibm->count)) {
106 			spin_lock_irqsave(&xibm->lock, flags);
107 			clear_bit(irq - xibm->base, xibm->bitmap);
108 			spin_unlock_irqrestore(&xibm->lock, flags);
109 			break;
110 		}
111 	}
112 }
113 
114 
115 /* Based on the similar routines in RTAS */
116 static unsigned int plpar_busy_delay_time(long rc)
117 {
118 	unsigned int ms = 0;
119 
120 	if (H_IS_LONG_BUSY(rc)) {
121 		ms = get_longbusy_msecs(rc);
122 	} else if (rc == H_BUSY) {
123 		ms = 10; /* seems appropriate for XIVE hcalls */
124 	}
125 
126 	return ms;
127 }
128 
129 static unsigned int plpar_busy_delay(int rc)
130 {
131 	unsigned int ms;
132 
133 	ms = plpar_busy_delay_time(rc);
134 	if (ms)
135 		mdelay(ms);
136 
137 	return ms;
138 }
139 
140 /*
141  * Note: this call has a partition wide scope and can take a while to
142  * complete. If it returns H_LONG_BUSY_* it should be retried
143  * periodically.
144  */
145 static long plpar_int_reset(unsigned long flags)
146 {
147 	long rc;
148 
149 	do {
150 		rc = plpar_hcall_norets(H_INT_RESET, flags);
151 	} while (plpar_busy_delay(rc));
152 
153 	if (rc)
154 		pr_err("H_INT_RESET failed %ld\n", rc);
155 
156 	return rc;
157 }
158 
159 static long plpar_int_get_source_info(unsigned long flags,
160 				      unsigned long lisn,
161 				      unsigned long *src_flags,
162 				      unsigned long *eoi_page,
163 				      unsigned long *trig_page,
164 				      unsigned long *esb_shift)
165 {
166 	unsigned long retbuf[PLPAR_HCALL_BUFSIZE];
167 	long rc;
168 
169 	do {
170 		rc = plpar_hcall(H_INT_GET_SOURCE_INFO, retbuf, flags, lisn);
171 	} while (plpar_busy_delay(rc));
172 
173 	if (rc) {
174 		pr_err("H_INT_GET_SOURCE_INFO lisn=%ld failed %ld\n", lisn, rc);
175 		return rc;
176 	}
177 
178 	*src_flags = retbuf[0];
179 	*eoi_page  = retbuf[1];
180 	*trig_page = retbuf[2];
181 	*esb_shift = retbuf[3];
182 
183 	pr_devel("H_INT_GET_SOURCE_INFO flags=%lx eoi=%lx trig=%lx shift=%lx\n",
184 		retbuf[0], retbuf[1], retbuf[2], retbuf[3]);
185 
186 	return 0;
187 }
188 
189 #define XIVE_SRC_SET_EISN (1ull << (63 - 62))
190 #define XIVE_SRC_MASK     (1ull << (63 - 63)) /* unused */
191 
192 static long plpar_int_set_source_config(unsigned long flags,
193 					unsigned long lisn,
194 					unsigned long target,
195 					unsigned long prio,
196 					unsigned long sw_irq)
197 {
198 	long rc;
199 
200 
201 	pr_devel("H_INT_SET_SOURCE_CONFIG flags=%lx lisn=%lx target=%lx prio=%lx sw_irq=%lx\n",
202 		flags, lisn, target, prio, sw_irq);
203 
204 
205 	do {
206 		rc = plpar_hcall_norets(H_INT_SET_SOURCE_CONFIG, flags, lisn,
207 					target, prio, sw_irq);
208 	} while (plpar_busy_delay(rc));
209 
210 	if (rc) {
211 		pr_err("H_INT_SET_SOURCE_CONFIG lisn=%ld target=%lx prio=%lx failed %ld\n",
212 		       lisn, target, prio, rc);
213 		return rc;
214 	}
215 
216 	return 0;
217 }
218 
219 static long plpar_int_get_source_config(unsigned long flags,
220 					unsigned long lisn,
221 					unsigned long *target,
222 					unsigned long *prio,
223 					unsigned long *sw_irq)
224 {
225 	unsigned long retbuf[PLPAR_HCALL_BUFSIZE];
226 	long rc;
227 
228 	pr_devel("H_INT_GET_SOURCE_CONFIG flags=%lx lisn=%lx\n", flags, lisn);
229 
230 	do {
231 		rc = plpar_hcall(H_INT_GET_SOURCE_CONFIG, retbuf, flags, lisn,
232 				 target, prio, sw_irq);
233 	} while (plpar_busy_delay(rc));
234 
235 	if (rc) {
236 		pr_err("H_INT_GET_SOURCE_CONFIG lisn=%ld failed %ld\n",
237 		       lisn, rc);
238 		return rc;
239 	}
240 
241 	*target = retbuf[0];
242 	*prio   = retbuf[1];
243 	*sw_irq = retbuf[2];
244 
245 	pr_devel("H_INT_GET_SOURCE_CONFIG target=%lx prio=%lx sw_irq=%lx\n",
246 		retbuf[0], retbuf[1], retbuf[2]);
247 
248 	return 0;
249 }
250 
251 static long plpar_int_get_queue_info(unsigned long flags,
252 				     unsigned long target,
253 				     unsigned long priority,
254 				     unsigned long *esn_page,
255 				     unsigned long *esn_size)
256 {
257 	unsigned long retbuf[PLPAR_HCALL_BUFSIZE];
258 	long rc;
259 
260 	do {
261 		rc = plpar_hcall(H_INT_GET_QUEUE_INFO, retbuf, flags, target,
262 				 priority);
263 	} while (plpar_busy_delay(rc));
264 
265 	if (rc) {
266 		pr_err("H_INT_GET_QUEUE_INFO cpu=%ld prio=%ld failed %ld\n",
267 		       target, priority, rc);
268 		return rc;
269 	}
270 
271 	*esn_page = retbuf[0];
272 	*esn_size = retbuf[1];
273 
274 	pr_devel("H_INT_GET_QUEUE_INFO page=%lx size=%lx\n",
275 		retbuf[0], retbuf[1]);
276 
277 	return 0;
278 }
279 
280 #define XIVE_EQ_ALWAYS_NOTIFY (1ull << (63 - 63))
281 
282 static long plpar_int_set_queue_config(unsigned long flags,
283 				       unsigned long target,
284 				       unsigned long priority,
285 				       unsigned long qpage,
286 				       unsigned long qsize)
287 {
288 	long rc;
289 
290 	pr_devel("H_INT_SET_QUEUE_CONFIG flags=%lx target=%lx priority=%lx qpage=%lx qsize=%lx\n",
291 		flags,  target, priority, qpage, qsize);
292 
293 	do {
294 		rc = plpar_hcall_norets(H_INT_SET_QUEUE_CONFIG, flags, target,
295 					priority, qpage, qsize);
296 	} while (plpar_busy_delay(rc));
297 
298 	if (rc) {
299 		pr_err("H_INT_SET_QUEUE_CONFIG cpu=%ld prio=%ld qpage=%lx returned %ld\n",
300 		       target, priority, qpage, rc);
301 		return  rc;
302 	}
303 
304 	return 0;
305 }
306 
307 static long plpar_int_sync(unsigned long flags, unsigned long lisn)
308 {
309 	long rc;
310 
311 	do {
312 		rc = plpar_hcall_norets(H_INT_SYNC, flags, lisn);
313 	} while (plpar_busy_delay(rc));
314 
315 	if (rc) {
316 		pr_err("H_INT_SYNC lisn=%ld returned %ld\n", lisn, rc);
317 		return  rc;
318 	}
319 
320 	return 0;
321 }
322 
323 #define XIVE_ESB_FLAG_STORE (1ull << (63 - 63))
324 
325 static long plpar_int_esb(unsigned long flags,
326 			  unsigned long lisn,
327 			  unsigned long offset,
328 			  unsigned long in_data,
329 			  unsigned long *out_data)
330 {
331 	unsigned long retbuf[PLPAR_HCALL_BUFSIZE];
332 	long rc;
333 
334 	pr_devel("H_INT_ESB flags=%lx lisn=%lx offset=%lx in=%lx\n",
335 		flags,  lisn, offset, in_data);
336 
337 	do {
338 		rc = plpar_hcall(H_INT_ESB, retbuf, flags, lisn, offset,
339 				 in_data);
340 	} while (plpar_busy_delay(rc));
341 
342 	if (rc) {
343 		pr_err("H_INT_ESB lisn=%ld offset=%ld returned %ld\n",
344 		       lisn, offset, rc);
345 		return  rc;
346 	}
347 
348 	*out_data = retbuf[0];
349 
350 	return 0;
351 }
352 
353 static u64 xive_spapr_esb_rw(u32 lisn, u32 offset, u64 data, bool write)
354 {
355 	unsigned long read_data;
356 	long rc;
357 
358 	rc = plpar_int_esb(write ? XIVE_ESB_FLAG_STORE : 0,
359 			   lisn, offset, data, &read_data);
360 	if (rc)
361 		return -1;
362 
363 	return write ? 0 : read_data;
364 }
365 
366 #define XIVE_SRC_H_INT_ESB     (1ull << (63 - 60))
367 #define XIVE_SRC_LSI           (1ull << (63 - 61))
368 #define XIVE_SRC_TRIGGER       (1ull << (63 - 62))
369 #define XIVE_SRC_STORE_EOI     (1ull << (63 - 63))
370 
371 static int xive_spapr_populate_irq_data(u32 hw_irq, struct xive_irq_data *data)
372 {
373 	long rc;
374 	unsigned long flags;
375 	unsigned long eoi_page;
376 	unsigned long trig_page;
377 	unsigned long esb_shift;
378 
379 	memset(data, 0, sizeof(*data));
380 
381 	rc = plpar_int_get_source_info(0, hw_irq, &flags, &eoi_page, &trig_page,
382 				       &esb_shift);
383 	if (rc)
384 		return  -EINVAL;
385 
386 	if (flags & XIVE_SRC_H_INT_ESB)
387 		data->flags  |= XIVE_IRQ_FLAG_H_INT_ESB;
388 	if (flags & XIVE_SRC_STORE_EOI)
389 		data->flags  |= XIVE_IRQ_FLAG_STORE_EOI;
390 	if (flags & XIVE_SRC_LSI)
391 		data->flags  |= XIVE_IRQ_FLAG_LSI;
392 	data->eoi_page  = eoi_page;
393 	data->esb_shift = esb_shift;
394 	data->trig_page = trig_page;
395 
396 	data->hw_irq = hw_irq;
397 
398 	/*
399 	 * No chip-id for the sPAPR backend. This has an impact how we
400 	 * pick a target. See xive_pick_irq_target().
401 	 */
402 	data->src_chip = XIVE_INVALID_CHIP_ID;
403 
404 	/*
405 	 * When the H_INT_ESB flag is set, the H_INT_ESB hcall should
406 	 * be used for interrupt management. Skip the remapping of the
407 	 * ESB pages which are not available.
408 	 */
409 	if (data->flags & XIVE_IRQ_FLAG_H_INT_ESB)
410 		return 0;
411 
412 	data->eoi_mmio = ioremap(data->eoi_page, 1u << data->esb_shift);
413 	if (!data->eoi_mmio) {
414 		pr_err("Failed to map EOI page for irq 0x%x\n", hw_irq);
415 		return -ENOMEM;
416 	}
417 
418 	/* Full function page supports trigger */
419 	if (flags & XIVE_SRC_TRIGGER) {
420 		data->trig_mmio = data->eoi_mmio;
421 		return 0;
422 	}
423 
424 	data->trig_mmio = ioremap(data->trig_page, 1u << data->esb_shift);
425 	if (!data->trig_mmio) {
426 		pr_err("Failed to map trigger page for irq 0x%x\n", hw_irq);
427 		return -ENOMEM;
428 	}
429 	return 0;
430 }
431 
432 static int xive_spapr_configure_irq(u32 hw_irq, u32 target, u8 prio, u32 sw_irq)
433 {
434 	long rc;
435 
436 	rc = plpar_int_set_source_config(XIVE_SRC_SET_EISN, hw_irq, target,
437 					 prio, sw_irq);
438 
439 	return rc == 0 ? 0 : -ENXIO;
440 }
441 
442 static int xive_spapr_get_irq_config(u32 hw_irq, u32 *target, u8 *prio,
443 				     u32 *sw_irq)
444 {
445 	long rc;
446 	unsigned long h_target;
447 	unsigned long h_prio;
448 	unsigned long h_sw_irq;
449 
450 	rc = plpar_int_get_source_config(0, hw_irq, &h_target, &h_prio,
451 					 &h_sw_irq);
452 
453 	*target = h_target;
454 	*prio = h_prio;
455 	*sw_irq = h_sw_irq;
456 
457 	return rc == 0 ? 0 : -ENXIO;
458 }
459 
460 /* This can be called multiple time to change a queue configuration */
461 static int xive_spapr_configure_queue(u32 target, struct xive_q *q, u8 prio,
462 				   __be32 *qpage, u32 order)
463 {
464 	s64 rc = 0;
465 	unsigned long esn_page;
466 	unsigned long esn_size;
467 	u64 flags, qpage_phys;
468 
469 	/* If there's an actual queue page, clean it */
470 	if (order) {
471 		if (WARN_ON(!qpage))
472 			return -EINVAL;
473 		qpage_phys = __pa(qpage);
474 	} else {
475 		qpage_phys = 0;
476 	}
477 
478 	/* Initialize the rest of the fields */
479 	q->msk = order ? ((1u << (order - 2)) - 1) : 0;
480 	q->idx = 0;
481 	q->toggle = 0;
482 
483 	rc = plpar_int_get_queue_info(0, target, prio, &esn_page, &esn_size);
484 	if (rc) {
485 		pr_err("Error %lld getting queue info CPU %d prio %d\n", rc,
486 		       target, prio);
487 		rc = -EIO;
488 		goto fail;
489 	}
490 
491 	/* TODO: add support for the notification page */
492 	q->eoi_phys = esn_page;
493 
494 	/* Default is to always notify */
495 	flags = XIVE_EQ_ALWAYS_NOTIFY;
496 
497 	/* Configure and enable the queue in HW */
498 	rc = plpar_int_set_queue_config(flags, target, prio, qpage_phys, order);
499 	if (rc) {
500 		pr_err("Error %lld setting queue for CPU %d prio %d\n", rc,
501 		       target, prio);
502 		rc = -EIO;
503 	} else {
504 		q->qpage = qpage;
505 	}
506 fail:
507 	return rc;
508 }
509 
510 static int xive_spapr_setup_queue(unsigned int cpu, struct xive_cpu *xc,
511 				  u8 prio)
512 {
513 	struct xive_q *q = &xc->queue[prio];
514 	__be32 *qpage;
515 
516 	qpage = xive_queue_page_alloc(cpu, xive_queue_shift);
517 	if (IS_ERR(qpage))
518 		return PTR_ERR(qpage);
519 
520 	return xive_spapr_configure_queue(get_hard_smp_processor_id(cpu),
521 					  q, prio, qpage, xive_queue_shift);
522 }
523 
524 static void xive_spapr_cleanup_queue(unsigned int cpu, struct xive_cpu *xc,
525 				  u8 prio)
526 {
527 	struct xive_q *q = &xc->queue[prio];
528 	unsigned int alloc_order;
529 	long rc;
530 	int hw_cpu = get_hard_smp_processor_id(cpu);
531 
532 	rc = plpar_int_set_queue_config(0, hw_cpu, prio, 0, 0);
533 	if (rc)
534 		pr_err("Error %ld setting queue for CPU %d prio %d\n", rc,
535 		       hw_cpu, prio);
536 
537 	alloc_order = xive_alloc_order(xive_queue_shift);
538 	free_pages((unsigned long)q->qpage, alloc_order);
539 	q->qpage = NULL;
540 }
541 
542 static bool xive_spapr_match(struct device_node *node)
543 {
544 	/* Ignore cascaded controllers for the moment */
545 	return 1;
546 }
547 
548 #ifdef CONFIG_SMP
549 static int xive_spapr_get_ipi(unsigned int cpu, struct xive_cpu *xc)
550 {
551 	int irq = xive_irq_bitmap_alloc();
552 
553 	if (irq < 0) {
554 		pr_err("Failed to allocate IPI on CPU %d\n", cpu);
555 		return -ENXIO;
556 	}
557 
558 	xc->hw_ipi = irq;
559 	return 0;
560 }
561 
562 static void xive_spapr_put_ipi(unsigned int cpu, struct xive_cpu *xc)
563 {
564 	if (xc->hw_ipi == XIVE_BAD_IRQ)
565 		return;
566 
567 	xive_irq_bitmap_free(xc->hw_ipi);
568 	xc->hw_ipi = XIVE_BAD_IRQ;
569 }
570 #endif /* CONFIG_SMP */
571 
572 static void xive_spapr_shutdown(void)
573 {
574 	plpar_int_reset(0);
575 }
576 
577 /*
578  * Perform an "ack" cycle on the current thread. Grab the pending
579  * active priorities and update the CPPR to the most favored one.
580  */
581 static void xive_spapr_update_pending(struct xive_cpu *xc)
582 {
583 	u8 nsr, cppr;
584 	u16 ack;
585 
586 	/*
587 	 * Perform the "Acknowledge O/S to Register" cycle.
588 	 *
589 	 * Let's speedup the access to the TIMA using the raw I/O
590 	 * accessor as we don't need the synchronisation routine of
591 	 * the higher level ones
592 	 */
593 	ack = be16_to_cpu(__raw_readw(xive_tima + TM_SPC_ACK_OS_REG));
594 
595 	/* Synchronize subsequent queue accesses */
596 	mb();
597 
598 	/*
599 	 * Grab the CPPR and the "NSR" field which indicates the source
600 	 * of the interrupt (if any)
601 	 */
602 	cppr = ack & 0xff;
603 	nsr = ack >> 8;
604 
605 	if (nsr & TM_QW1_NSR_EO) {
606 		if (cppr == 0xff)
607 			return;
608 		/* Mark the priority pending */
609 		xc->pending_prio |= 1 << cppr;
610 
611 		/*
612 		 * A new interrupt should never have a CPPR less favored
613 		 * than our current one.
614 		 */
615 		if (cppr >= xc->cppr)
616 			pr_err("CPU %d odd ack CPPR, got %d at %d\n",
617 			       smp_processor_id(), cppr, xc->cppr);
618 
619 		/* Update our idea of what the CPPR is */
620 		xc->cppr = cppr;
621 	}
622 }
623 
624 static void xive_spapr_eoi(u32 hw_irq)
625 {
626 	/* Not used */;
627 }
628 
629 static void xive_spapr_setup_cpu(unsigned int cpu, struct xive_cpu *xc)
630 {
631 	/* Only some debug on the TIMA settings */
632 	pr_debug("(HW value: %08x %08x %08x)\n",
633 		 in_be32(xive_tima + TM_QW1_OS + TM_WORD0),
634 		 in_be32(xive_tima + TM_QW1_OS + TM_WORD1),
635 		 in_be32(xive_tima + TM_QW1_OS + TM_WORD2));
636 }
637 
638 static void xive_spapr_teardown_cpu(unsigned int cpu, struct xive_cpu *xc)
639 {
640 	/* Nothing to do */;
641 }
642 
643 static void xive_spapr_sync_source(u32 hw_irq)
644 {
645 	/* Specs are unclear on what this is doing */
646 	plpar_int_sync(0, hw_irq);
647 }
648 
649 static int xive_spapr_debug_show(struct seq_file *m, void *private)
650 {
651 	struct xive_irq_bitmap *xibm;
652 	char *buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
653 
654 	list_for_each_entry(xibm, &xive_irq_bitmaps, list) {
655 		memset(buf, 0, PAGE_SIZE);
656 		bitmap_print_to_pagebuf(true, buf, xibm->bitmap, xibm->count);
657 		seq_printf(m, "bitmap #%d: %s", xibm->count, buf);
658 	}
659 	kfree(buf);
660 
661 	return 0;
662 }
663 
664 static const struct xive_ops xive_spapr_ops = {
665 	.populate_irq_data	= xive_spapr_populate_irq_data,
666 	.configure_irq		= xive_spapr_configure_irq,
667 	.get_irq_config		= xive_spapr_get_irq_config,
668 	.setup_queue		= xive_spapr_setup_queue,
669 	.cleanup_queue		= xive_spapr_cleanup_queue,
670 	.match			= xive_spapr_match,
671 	.shutdown		= xive_spapr_shutdown,
672 	.update_pending		= xive_spapr_update_pending,
673 	.eoi			= xive_spapr_eoi,
674 	.setup_cpu		= xive_spapr_setup_cpu,
675 	.teardown_cpu		= xive_spapr_teardown_cpu,
676 	.sync_source		= xive_spapr_sync_source,
677 	.esb_rw			= xive_spapr_esb_rw,
678 #ifdef CONFIG_SMP
679 	.get_ipi		= xive_spapr_get_ipi,
680 	.put_ipi		= xive_spapr_put_ipi,
681 	.debug_show		= xive_spapr_debug_show,
682 #endif /* CONFIG_SMP */
683 	.name			= "spapr",
684 };
685 
686 /*
687  * get max priority from "/ibm,plat-res-int-priorities"
688  */
689 static bool xive_get_max_prio(u8 *max_prio)
690 {
691 	struct device_node *rootdn;
692 	const __be32 *reg;
693 	u32 len;
694 	int prio, found;
695 
696 	rootdn = of_find_node_by_path("/");
697 	if (!rootdn) {
698 		pr_err("not root node found !\n");
699 		return false;
700 	}
701 
702 	reg = of_get_property(rootdn, "ibm,plat-res-int-priorities", &len);
703 	if (!reg) {
704 		pr_err("Failed to read 'ibm,plat-res-int-priorities' property\n");
705 		return false;
706 	}
707 
708 	if (len % (2 * sizeof(u32)) != 0) {
709 		pr_err("invalid 'ibm,plat-res-int-priorities' property\n");
710 		return false;
711 	}
712 
713 	/* HW supports priorities in the range [0-7] and 0xFF is a
714 	 * wildcard priority used to mask. We scan the ranges reserved
715 	 * by the hypervisor to find the lowest priority we can use.
716 	 */
717 	found = 0xFF;
718 	for (prio = 0; prio < 8; prio++) {
719 		int reserved = 0;
720 		int i;
721 
722 		for (i = 0; i < len / (2 * sizeof(u32)); i++) {
723 			int base  = be32_to_cpu(reg[2 * i]);
724 			int range = be32_to_cpu(reg[2 * i + 1]);
725 
726 			if (prio >= base && prio < base + range)
727 				reserved++;
728 		}
729 
730 		if (!reserved)
731 			found = prio;
732 	}
733 
734 	if (found == 0xFF) {
735 		pr_err("no valid priority found in 'ibm,plat-res-int-priorities'\n");
736 		return false;
737 	}
738 
739 	*max_prio = found;
740 	return true;
741 }
742 
743 static const u8 *get_vec5_feature(unsigned int index)
744 {
745 	unsigned long root, chosen;
746 	int size;
747 	const u8 *vec5;
748 
749 	root = of_get_flat_dt_root();
750 	chosen = of_get_flat_dt_subnode_by_name(root, "chosen");
751 	if (chosen == -FDT_ERR_NOTFOUND)
752 		return NULL;
753 
754 	vec5 = of_get_flat_dt_prop(chosen, "ibm,architecture-vec-5", &size);
755 	if (!vec5)
756 		return NULL;
757 
758 	if (size <= index)
759 		return NULL;
760 
761 	return vec5 + index;
762 }
763 
764 static bool xive_spapr_disabled(void)
765 {
766 	const u8 *vec5_xive;
767 
768 	vec5_xive = get_vec5_feature(OV5_INDX(OV5_XIVE_SUPPORT));
769 	if (vec5_xive) {
770 		u8 val;
771 
772 		val = *vec5_xive & OV5_FEAT(OV5_XIVE_SUPPORT);
773 		switch (val) {
774 		case OV5_FEAT(OV5_XIVE_EITHER):
775 		case OV5_FEAT(OV5_XIVE_LEGACY):
776 			break;
777 		case OV5_FEAT(OV5_XIVE_EXPLOIT):
778 			/* Hypervisor only supports XIVE */
779 			if (xive_cmdline_disabled)
780 				pr_warn("WARNING: Ignoring cmdline option xive=off\n");
781 			return false;
782 		default:
783 			pr_warn("%s: Unknown xive support option: 0x%x\n",
784 				__func__, val);
785 			break;
786 		}
787 	}
788 
789 	return xive_cmdline_disabled;
790 }
791 
792 bool __init xive_spapr_init(void)
793 {
794 	struct device_node *np;
795 	struct resource r;
796 	void __iomem *tima;
797 	struct property *prop;
798 	u8 max_prio;
799 	u32 val;
800 	u32 len;
801 	const __be32 *reg;
802 	int i;
803 
804 	if (xive_spapr_disabled())
805 		return false;
806 
807 	pr_devel("%s()\n", __func__);
808 	np = of_find_compatible_node(NULL, NULL, "ibm,power-ivpe");
809 	if (!np) {
810 		pr_devel("not found !\n");
811 		return false;
812 	}
813 	pr_devel("Found %s\n", np->full_name);
814 
815 	/* Resource 1 is the OS ring TIMA */
816 	if (of_address_to_resource(np, 1, &r)) {
817 		pr_err("Failed to get thread mgmnt area resource\n");
818 		return false;
819 	}
820 	tima = ioremap(r.start, resource_size(&r));
821 	if (!tima) {
822 		pr_err("Failed to map thread mgmnt area\n");
823 		return false;
824 	}
825 
826 	if (!xive_get_max_prio(&max_prio))
827 		return false;
828 
829 	/* Feed the IRQ number allocator with the ranges given in the DT */
830 	reg = of_get_property(np, "ibm,xive-lisn-ranges", &len);
831 	if (!reg) {
832 		pr_err("Failed to read 'ibm,xive-lisn-ranges' property\n");
833 		return false;
834 	}
835 
836 	if (len % (2 * sizeof(u32)) != 0) {
837 		pr_err("invalid 'ibm,xive-lisn-ranges' property\n");
838 		return false;
839 	}
840 
841 	for (i = 0; i < len / (2 * sizeof(u32)); i++, reg += 2)
842 		xive_irq_bitmap_add(be32_to_cpu(reg[0]),
843 				    be32_to_cpu(reg[1]));
844 
845 	/* Iterate the EQ sizes and pick one */
846 	of_property_for_each_u32(np, "ibm,xive-eq-sizes", prop, reg, val) {
847 		xive_queue_shift = val;
848 		if (val == PAGE_SHIFT)
849 			break;
850 	}
851 
852 	/* Initialize XIVE core with our backend */
853 	if (!xive_core_init(&xive_spapr_ops, tima, TM_QW1_OS, max_prio))
854 		return false;
855 
856 	pr_info("Using %dkB queues\n", 1 << (xive_queue_shift - 10));
857 	return true;
858 }
859 
860 machine_arch_initcall(pseries, xive_core_debug_init);
861