xref: /openbmc/linux/drivers/iommu/tegra-smmu.c (revision 4bce6fce)
1 /*
2  * Copyright (C) 2011-2014 NVIDIA CORPORATION.  All rights reserved.
3  *
4  * This program is free software; you can redistribute it and/or modify
5  * it under the terms of the GNU General Public License version 2 as
6  * published by the Free Software Foundation.
7  */
8 
9 #include <linux/bitops.h>
10 #include <linux/err.h>
11 #include <linux/iommu.h>
12 #include <linux/kernel.h>
13 #include <linux/of.h>
14 #include <linux/of_device.h>
15 #include <linux/platform_device.h>
16 #include <linux/slab.h>
17 
18 #include <soc/tegra/ahb.h>
19 #include <soc/tegra/mc.h>
20 
21 struct tegra_smmu {
22 	void __iomem *regs;
23 	struct device *dev;
24 
25 	struct tegra_mc *mc;
26 	const struct tegra_smmu_soc *soc;
27 
28 	unsigned long pfn_mask;
29 
30 	unsigned long *asids;
31 	struct mutex lock;
32 
33 	struct list_head list;
34 };
35 
36 struct tegra_smmu_as {
37 	struct iommu_domain domain;
38 	struct tegra_smmu *smmu;
39 	unsigned int use_count;
40 	struct page *count;
41 	struct page *pd;
42 	unsigned id;
43 	u32 attr;
44 };
45 
46 static struct tegra_smmu_as *to_smmu_as(struct iommu_domain *dom)
47 {
48 	return container_of(dom, struct tegra_smmu_as, domain);
49 }
50 
51 static inline void smmu_writel(struct tegra_smmu *smmu, u32 value,
52 			       unsigned long offset)
53 {
54 	writel(value, smmu->regs + offset);
55 }
56 
57 static inline u32 smmu_readl(struct tegra_smmu *smmu, unsigned long offset)
58 {
59 	return readl(smmu->regs + offset);
60 }
61 
62 #define SMMU_CONFIG 0x010
63 #define  SMMU_CONFIG_ENABLE (1 << 0)
64 
65 #define SMMU_TLB_CONFIG 0x14
66 #define  SMMU_TLB_CONFIG_HIT_UNDER_MISS (1 << 29)
67 #define  SMMU_TLB_CONFIG_ROUND_ROBIN_ARBITRATION (1 << 28)
68 #define  SMMU_TLB_CONFIG_ACTIVE_LINES(x) ((x) & 0x3f)
69 
70 #define SMMU_PTC_CONFIG 0x18
71 #define  SMMU_PTC_CONFIG_ENABLE (1 << 29)
72 #define  SMMU_PTC_CONFIG_REQ_LIMIT(x) (((x) & 0x0f) << 24)
73 #define  SMMU_PTC_CONFIG_INDEX_MAP(x) ((x) & 0x3f)
74 
75 #define SMMU_PTB_ASID 0x01c
76 #define  SMMU_PTB_ASID_VALUE(x) ((x) & 0x7f)
77 
78 #define SMMU_PTB_DATA 0x020
79 #define  SMMU_PTB_DATA_VALUE(page, attr) (page_to_phys(page) >> 12 | (attr))
80 
81 #define SMMU_MK_PDE(page, attr) (page_to_phys(page) >> SMMU_PTE_SHIFT | (attr))
82 
83 #define SMMU_TLB_FLUSH 0x030
84 #define  SMMU_TLB_FLUSH_VA_MATCH_ALL     (0 << 0)
85 #define  SMMU_TLB_FLUSH_VA_MATCH_SECTION (2 << 0)
86 #define  SMMU_TLB_FLUSH_VA_MATCH_GROUP   (3 << 0)
87 #define  SMMU_TLB_FLUSH_ASID(x)          (((x) & 0x7f) << 24)
88 #define  SMMU_TLB_FLUSH_VA_SECTION(addr) ((((addr) & 0xffc00000) >> 12) | \
89 					  SMMU_TLB_FLUSH_VA_MATCH_SECTION)
90 #define  SMMU_TLB_FLUSH_VA_GROUP(addr)   ((((addr) & 0xffffc000) >> 12) | \
91 					  SMMU_TLB_FLUSH_VA_MATCH_GROUP)
92 #define  SMMU_TLB_FLUSH_ASID_MATCH       (1 << 31)
93 
94 #define SMMU_PTC_FLUSH 0x034
95 #define  SMMU_PTC_FLUSH_TYPE_ALL (0 << 0)
96 #define  SMMU_PTC_FLUSH_TYPE_ADR (1 << 0)
97 
98 #define SMMU_PTC_FLUSH_HI 0x9b8
99 #define  SMMU_PTC_FLUSH_HI_MASK 0x3
100 
101 /* per-SWGROUP SMMU_*_ASID register */
102 #define SMMU_ASID_ENABLE (1 << 31)
103 #define SMMU_ASID_MASK 0x7f
104 #define SMMU_ASID_VALUE(x) ((x) & SMMU_ASID_MASK)
105 
106 /* page table definitions */
107 #define SMMU_NUM_PDE 1024
108 #define SMMU_NUM_PTE 1024
109 
110 #define SMMU_SIZE_PD (SMMU_NUM_PDE * 4)
111 #define SMMU_SIZE_PT (SMMU_NUM_PTE * 4)
112 
113 #define SMMU_PDE_SHIFT 22
114 #define SMMU_PTE_SHIFT 12
115 
116 #define SMMU_PD_READABLE	(1 << 31)
117 #define SMMU_PD_WRITABLE	(1 << 30)
118 #define SMMU_PD_NONSECURE	(1 << 29)
119 
120 #define SMMU_PDE_READABLE	(1 << 31)
121 #define SMMU_PDE_WRITABLE	(1 << 30)
122 #define SMMU_PDE_NONSECURE	(1 << 29)
123 #define SMMU_PDE_NEXT		(1 << 28)
124 
125 #define SMMU_PTE_READABLE	(1 << 31)
126 #define SMMU_PTE_WRITABLE	(1 << 30)
127 #define SMMU_PTE_NONSECURE	(1 << 29)
128 
129 #define SMMU_PDE_ATTR		(SMMU_PDE_READABLE | SMMU_PDE_WRITABLE | \
130 				 SMMU_PDE_NONSECURE)
131 #define SMMU_PTE_ATTR		(SMMU_PTE_READABLE | SMMU_PTE_WRITABLE | \
132 				 SMMU_PTE_NONSECURE)
133 
134 static inline void smmu_flush_ptc(struct tegra_smmu *smmu, struct page *page,
135 				  unsigned long offset)
136 {
137 	phys_addr_t phys = page ? page_to_phys(page) : 0;
138 	u32 value;
139 
140 	if (page) {
141 		offset &= ~(smmu->mc->soc->atom_size - 1);
142 
143 		if (smmu->mc->soc->num_address_bits > 32) {
144 #ifdef CONFIG_PHYS_ADDR_T_64BIT
145 			value = (phys >> 32) & SMMU_PTC_FLUSH_HI_MASK;
146 #else
147 			value = 0;
148 #endif
149 			smmu_writel(smmu, value, SMMU_PTC_FLUSH_HI);
150 		}
151 
152 		value = (phys + offset) | SMMU_PTC_FLUSH_TYPE_ADR;
153 	} else {
154 		value = SMMU_PTC_FLUSH_TYPE_ALL;
155 	}
156 
157 	smmu_writel(smmu, value, SMMU_PTC_FLUSH);
158 }
159 
160 static inline void smmu_flush_tlb(struct tegra_smmu *smmu)
161 {
162 	smmu_writel(smmu, SMMU_TLB_FLUSH_VA_MATCH_ALL, SMMU_TLB_FLUSH);
163 }
164 
165 static inline void smmu_flush_tlb_asid(struct tegra_smmu *smmu,
166 				       unsigned long asid)
167 {
168 	u32 value;
169 
170 	value = SMMU_TLB_FLUSH_ASID_MATCH | SMMU_TLB_FLUSH_ASID(asid) |
171 		SMMU_TLB_FLUSH_VA_MATCH_ALL;
172 	smmu_writel(smmu, value, SMMU_TLB_FLUSH);
173 }
174 
175 static inline void smmu_flush_tlb_section(struct tegra_smmu *smmu,
176 					  unsigned long asid,
177 					  unsigned long iova)
178 {
179 	u32 value;
180 
181 	value = SMMU_TLB_FLUSH_ASID_MATCH | SMMU_TLB_FLUSH_ASID(asid) |
182 		SMMU_TLB_FLUSH_VA_SECTION(iova);
183 	smmu_writel(smmu, value, SMMU_TLB_FLUSH);
184 }
185 
186 static inline void smmu_flush_tlb_group(struct tegra_smmu *smmu,
187 					unsigned long asid,
188 					unsigned long iova)
189 {
190 	u32 value;
191 
192 	value = SMMU_TLB_FLUSH_ASID_MATCH | SMMU_TLB_FLUSH_ASID(asid) |
193 		SMMU_TLB_FLUSH_VA_GROUP(iova);
194 	smmu_writel(smmu, value, SMMU_TLB_FLUSH);
195 }
196 
197 static inline void smmu_flush(struct tegra_smmu *smmu)
198 {
199 	smmu_readl(smmu, SMMU_CONFIG);
200 }
201 
202 static int tegra_smmu_alloc_asid(struct tegra_smmu *smmu, unsigned int *idp)
203 {
204 	unsigned long id;
205 
206 	mutex_lock(&smmu->lock);
207 
208 	id = find_first_zero_bit(smmu->asids, smmu->soc->num_asids);
209 	if (id >= smmu->soc->num_asids) {
210 		mutex_unlock(&smmu->lock);
211 		return -ENOSPC;
212 	}
213 
214 	set_bit(id, smmu->asids);
215 	*idp = id;
216 
217 	mutex_unlock(&smmu->lock);
218 	return 0;
219 }
220 
221 static void tegra_smmu_free_asid(struct tegra_smmu *smmu, unsigned int id)
222 {
223 	mutex_lock(&smmu->lock);
224 	clear_bit(id, smmu->asids);
225 	mutex_unlock(&smmu->lock);
226 }
227 
228 static bool tegra_smmu_capable(enum iommu_cap cap)
229 {
230 	return false;
231 }
232 
233 static struct iommu_domain *tegra_smmu_domain_alloc(unsigned type)
234 {
235 	struct tegra_smmu_as *as;
236 	unsigned int i;
237 	uint32_t *pd;
238 
239 	if (type != IOMMU_DOMAIN_UNMANAGED)
240 		return NULL;
241 
242 	as = kzalloc(sizeof(*as), GFP_KERNEL);
243 	if (!as)
244 		return NULL;
245 
246 	as->attr = SMMU_PD_READABLE | SMMU_PD_WRITABLE | SMMU_PD_NONSECURE;
247 
248 	as->pd = alloc_page(GFP_KERNEL | __GFP_DMA);
249 	if (!as->pd) {
250 		kfree(as);
251 		return NULL;
252 	}
253 
254 	as->count = alloc_page(GFP_KERNEL);
255 	if (!as->count) {
256 		__free_page(as->pd);
257 		kfree(as);
258 		return NULL;
259 	}
260 
261 	/* clear PDEs */
262 	pd = page_address(as->pd);
263 	SetPageReserved(as->pd);
264 
265 	for (i = 0; i < SMMU_NUM_PDE; i++)
266 		pd[i] = 0;
267 
268 	/* clear PDE usage counters */
269 	pd = page_address(as->count);
270 	SetPageReserved(as->count);
271 
272 	for (i = 0; i < SMMU_NUM_PDE; i++)
273 		pd[i] = 0;
274 
275 	/* setup aperture */
276 	as->domain.geometry.aperture_start = 0;
277 	as->domain.geometry.aperture_end = 0xffffffff;
278 	as->domain.geometry.force_aperture = true;
279 
280 	return &as->domain;
281 }
282 
283 static void tegra_smmu_domain_free(struct iommu_domain *domain)
284 {
285 	struct tegra_smmu_as *as = to_smmu_as(domain);
286 
287 	/* TODO: free page directory and page tables */
288 	ClearPageReserved(as->pd);
289 
290 	kfree(as);
291 }
292 
293 static const struct tegra_smmu_swgroup *
294 tegra_smmu_find_swgroup(struct tegra_smmu *smmu, unsigned int swgroup)
295 {
296 	const struct tegra_smmu_swgroup *group = NULL;
297 	unsigned int i;
298 
299 	for (i = 0; i < smmu->soc->num_swgroups; i++) {
300 		if (smmu->soc->swgroups[i].swgroup == swgroup) {
301 			group = &smmu->soc->swgroups[i];
302 			break;
303 		}
304 	}
305 
306 	return group;
307 }
308 
309 static void tegra_smmu_enable(struct tegra_smmu *smmu, unsigned int swgroup,
310 			      unsigned int asid)
311 {
312 	const struct tegra_smmu_swgroup *group;
313 	unsigned int i;
314 	u32 value;
315 
316 	for (i = 0; i < smmu->soc->num_clients; i++) {
317 		const struct tegra_mc_client *client = &smmu->soc->clients[i];
318 
319 		if (client->swgroup != swgroup)
320 			continue;
321 
322 		value = smmu_readl(smmu, client->smmu.reg);
323 		value |= BIT(client->smmu.bit);
324 		smmu_writel(smmu, value, client->smmu.reg);
325 	}
326 
327 	group = tegra_smmu_find_swgroup(smmu, swgroup);
328 	if (group) {
329 		value = smmu_readl(smmu, group->reg);
330 		value &= ~SMMU_ASID_MASK;
331 		value |= SMMU_ASID_VALUE(asid);
332 		value |= SMMU_ASID_ENABLE;
333 		smmu_writel(smmu, value, group->reg);
334 	}
335 }
336 
337 static void tegra_smmu_disable(struct tegra_smmu *smmu, unsigned int swgroup,
338 			       unsigned int asid)
339 {
340 	const struct tegra_smmu_swgroup *group;
341 	unsigned int i;
342 	u32 value;
343 
344 	group = tegra_smmu_find_swgroup(smmu, swgroup);
345 	if (group) {
346 		value = smmu_readl(smmu, group->reg);
347 		value &= ~SMMU_ASID_MASK;
348 		value |= SMMU_ASID_VALUE(asid);
349 		value &= ~SMMU_ASID_ENABLE;
350 		smmu_writel(smmu, value, group->reg);
351 	}
352 
353 	for (i = 0; i < smmu->soc->num_clients; i++) {
354 		const struct tegra_mc_client *client = &smmu->soc->clients[i];
355 
356 		if (client->swgroup != swgroup)
357 			continue;
358 
359 		value = smmu_readl(smmu, client->smmu.reg);
360 		value &= ~BIT(client->smmu.bit);
361 		smmu_writel(smmu, value, client->smmu.reg);
362 	}
363 }
364 
365 static int tegra_smmu_as_prepare(struct tegra_smmu *smmu,
366 				 struct tegra_smmu_as *as)
367 {
368 	u32 value;
369 	int err;
370 
371 	if (as->use_count > 0) {
372 		as->use_count++;
373 		return 0;
374 	}
375 
376 	err = tegra_smmu_alloc_asid(smmu, &as->id);
377 	if (err < 0)
378 		return err;
379 
380 	smmu->soc->ops->flush_dcache(as->pd, 0, SMMU_SIZE_PD);
381 	smmu_flush_ptc(smmu, as->pd, 0);
382 	smmu_flush_tlb_asid(smmu, as->id);
383 
384 	smmu_writel(smmu, as->id & 0x7f, SMMU_PTB_ASID);
385 	value = SMMU_PTB_DATA_VALUE(as->pd, as->attr);
386 	smmu_writel(smmu, value, SMMU_PTB_DATA);
387 	smmu_flush(smmu);
388 
389 	as->smmu = smmu;
390 	as->use_count++;
391 
392 	return 0;
393 }
394 
395 static void tegra_smmu_as_unprepare(struct tegra_smmu *smmu,
396 				    struct tegra_smmu_as *as)
397 {
398 	if (--as->use_count > 0)
399 		return;
400 
401 	tegra_smmu_free_asid(smmu, as->id);
402 	as->smmu = NULL;
403 }
404 
405 static int tegra_smmu_attach_dev(struct iommu_domain *domain,
406 				 struct device *dev)
407 {
408 	struct tegra_smmu *smmu = dev->archdata.iommu;
409 	struct tegra_smmu_as *as = to_smmu_as(domain);
410 	struct device_node *np = dev->of_node;
411 	struct of_phandle_args args;
412 	unsigned int index = 0;
413 	int err = 0;
414 
415 	while (!of_parse_phandle_with_args(np, "iommus", "#iommu-cells", index,
416 					   &args)) {
417 		unsigned int swgroup = args.args[0];
418 
419 		if (args.np != smmu->dev->of_node) {
420 			of_node_put(args.np);
421 			continue;
422 		}
423 
424 		of_node_put(args.np);
425 
426 		err = tegra_smmu_as_prepare(smmu, as);
427 		if (err < 0)
428 			return err;
429 
430 		tegra_smmu_enable(smmu, swgroup, as->id);
431 		index++;
432 	}
433 
434 	if (index == 0)
435 		return -ENODEV;
436 
437 	return 0;
438 }
439 
440 static void tegra_smmu_detach_dev(struct iommu_domain *domain, struct device *dev)
441 {
442 	struct tegra_smmu_as *as = to_smmu_as(domain);
443 	struct device_node *np = dev->of_node;
444 	struct tegra_smmu *smmu = as->smmu;
445 	struct of_phandle_args args;
446 	unsigned int index = 0;
447 
448 	while (!of_parse_phandle_with_args(np, "iommus", "#iommu-cells", index,
449 					   &args)) {
450 		unsigned int swgroup = args.args[0];
451 
452 		if (args.np != smmu->dev->of_node) {
453 			of_node_put(args.np);
454 			continue;
455 		}
456 
457 		of_node_put(args.np);
458 
459 		tegra_smmu_disable(smmu, swgroup, as->id);
460 		tegra_smmu_as_unprepare(smmu, as);
461 		index++;
462 	}
463 }
464 
465 static u32 *as_get_pte(struct tegra_smmu_as *as, dma_addr_t iova,
466 		       struct page **pagep)
467 {
468 	u32 *pd = page_address(as->pd), *pt, *count;
469 	u32 pde = (iova >> SMMU_PDE_SHIFT) & 0x3ff;
470 	u32 pte = (iova >> SMMU_PTE_SHIFT) & 0x3ff;
471 	struct tegra_smmu *smmu = as->smmu;
472 	struct page *page;
473 	unsigned int i;
474 
475 	if (pd[pde] == 0) {
476 		page = alloc_page(GFP_KERNEL | __GFP_DMA);
477 		if (!page)
478 			return NULL;
479 
480 		pt = page_address(page);
481 		SetPageReserved(page);
482 
483 		for (i = 0; i < SMMU_NUM_PTE; i++)
484 			pt[i] = 0;
485 
486 		smmu->soc->ops->flush_dcache(page, 0, SMMU_SIZE_PT);
487 
488 		pd[pde] = SMMU_MK_PDE(page, SMMU_PDE_ATTR | SMMU_PDE_NEXT);
489 
490 		smmu->soc->ops->flush_dcache(as->pd, pde << 2, 4);
491 		smmu_flush_ptc(smmu, as->pd, pde << 2);
492 		smmu_flush_tlb_section(smmu, as->id, iova);
493 		smmu_flush(smmu);
494 	} else {
495 		page = pfn_to_page(pd[pde] & smmu->pfn_mask);
496 		pt = page_address(page);
497 	}
498 
499 	*pagep = page;
500 
501 	/* Keep track of entries in this page table. */
502 	count = page_address(as->count);
503 	if (pt[pte] == 0)
504 		count[pde]++;
505 
506 	return &pt[pte];
507 }
508 
509 static void as_put_pte(struct tegra_smmu_as *as, dma_addr_t iova)
510 {
511 	u32 pde = (iova >> SMMU_PDE_SHIFT) & 0x3ff;
512 	u32 pte = (iova >> SMMU_PTE_SHIFT) & 0x3ff;
513 	u32 *count = page_address(as->count);
514 	u32 *pd = page_address(as->pd), *pt;
515 	struct page *page;
516 
517 	page = pfn_to_page(pd[pde] & as->smmu->pfn_mask);
518 	pt = page_address(page);
519 
520 	/*
521 	 * When no entries in this page table are used anymore, return the
522 	 * memory page to the system.
523 	 */
524 	if (pt[pte] != 0) {
525 		if (--count[pde] == 0) {
526 			ClearPageReserved(page);
527 			__free_page(page);
528 			pd[pde] = 0;
529 		}
530 
531 		pt[pte] = 0;
532 	}
533 }
534 
535 static int tegra_smmu_map(struct iommu_domain *domain, unsigned long iova,
536 			  phys_addr_t paddr, size_t size, int prot)
537 {
538 	struct tegra_smmu_as *as = to_smmu_as(domain);
539 	struct tegra_smmu *smmu = as->smmu;
540 	unsigned long offset;
541 	struct page *page;
542 	u32 *pte;
543 
544 	pte = as_get_pte(as, iova, &page);
545 	if (!pte)
546 		return -ENOMEM;
547 
548 	*pte = __phys_to_pfn(paddr) | SMMU_PTE_ATTR;
549 	offset = offset_in_page(pte);
550 
551 	smmu->soc->ops->flush_dcache(page, offset, 4);
552 	smmu_flush_ptc(smmu, page, offset);
553 	smmu_flush_tlb_group(smmu, as->id, iova);
554 	smmu_flush(smmu);
555 
556 	return 0;
557 }
558 
559 static size_t tegra_smmu_unmap(struct iommu_domain *domain, unsigned long iova,
560 			       size_t size)
561 {
562 	struct tegra_smmu_as *as = to_smmu_as(domain);
563 	struct tegra_smmu *smmu = as->smmu;
564 	unsigned long offset;
565 	struct page *page;
566 	u32 *pte;
567 
568 	pte = as_get_pte(as, iova, &page);
569 	if (!pte)
570 		return 0;
571 
572 	offset = offset_in_page(pte);
573 	as_put_pte(as, iova);
574 
575 	smmu->soc->ops->flush_dcache(page, offset, 4);
576 	smmu_flush_ptc(smmu, page, offset);
577 	smmu_flush_tlb_group(smmu, as->id, iova);
578 	smmu_flush(smmu);
579 
580 	return size;
581 }
582 
583 static phys_addr_t tegra_smmu_iova_to_phys(struct iommu_domain *domain,
584 					   dma_addr_t iova)
585 {
586 	struct tegra_smmu_as *as = to_smmu_as(domain);
587 	struct page *page;
588 	unsigned long pfn;
589 	u32 *pte;
590 
591 	pte = as_get_pte(as, iova, &page);
592 	pfn = *pte & as->smmu->pfn_mask;
593 
594 	return PFN_PHYS(pfn);
595 }
596 
597 static struct tegra_smmu *tegra_smmu_find(struct device_node *np)
598 {
599 	struct platform_device *pdev;
600 	struct tegra_mc *mc;
601 
602 	pdev = of_find_device_by_node(np);
603 	if (!pdev)
604 		return NULL;
605 
606 	mc = platform_get_drvdata(pdev);
607 	if (!mc)
608 		return NULL;
609 
610 	return mc->smmu;
611 }
612 
613 static int tegra_smmu_add_device(struct device *dev)
614 {
615 	struct device_node *np = dev->of_node;
616 	struct of_phandle_args args;
617 	unsigned int index = 0;
618 
619 	while (of_parse_phandle_with_args(np, "iommus", "#iommu-cells", index,
620 					  &args) == 0) {
621 		struct tegra_smmu *smmu;
622 
623 		smmu = tegra_smmu_find(args.np);
624 		if (smmu) {
625 			/*
626 			 * Only a single IOMMU master interface is currently
627 			 * supported by the Linux kernel, so abort after the
628 			 * first match.
629 			 */
630 			dev->archdata.iommu = smmu;
631 			break;
632 		}
633 
634 		index++;
635 	}
636 
637 	return 0;
638 }
639 
640 static void tegra_smmu_remove_device(struct device *dev)
641 {
642 	dev->archdata.iommu = NULL;
643 }
644 
645 static const struct iommu_ops tegra_smmu_ops = {
646 	.capable = tegra_smmu_capable,
647 	.domain_alloc = tegra_smmu_domain_alloc,
648 	.domain_free = tegra_smmu_domain_free,
649 	.attach_dev = tegra_smmu_attach_dev,
650 	.detach_dev = tegra_smmu_detach_dev,
651 	.add_device = tegra_smmu_add_device,
652 	.remove_device = tegra_smmu_remove_device,
653 	.map = tegra_smmu_map,
654 	.unmap = tegra_smmu_unmap,
655 	.map_sg = default_iommu_map_sg,
656 	.iova_to_phys = tegra_smmu_iova_to_phys,
657 
658 	.pgsize_bitmap = SZ_4K,
659 };
660 
661 static void tegra_smmu_ahb_enable(void)
662 {
663 	static const struct of_device_id ahb_match[] = {
664 		{ .compatible = "nvidia,tegra30-ahb", },
665 		{ }
666 	};
667 	struct device_node *ahb;
668 
669 	ahb = of_find_matching_node(NULL, ahb_match);
670 	if (ahb) {
671 		tegra_ahb_enable_smmu(ahb);
672 		of_node_put(ahb);
673 	}
674 }
675 
676 struct tegra_smmu *tegra_smmu_probe(struct device *dev,
677 				    const struct tegra_smmu_soc *soc,
678 				    struct tegra_mc *mc)
679 {
680 	struct tegra_smmu *smmu;
681 	size_t size;
682 	u32 value;
683 	int err;
684 
685 	/* This can happen on Tegra20 which doesn't have an SMMU */
686 	if (!soc)
687 		return NULL;
688 
689 	smmu = devm_kzalloc(dev, sizeof(*smmu), GFP_KERNEL);
690 	if (!smmu)
691 		return ERR_PTR(-ENOMEM);
692 
693 	/*
694 	 * This is a bit of a hack. Ideally we'd want to simply return this
695 	 * value. However the IOMMU registration process will attempt to add
696 	 * all devices to the IOMMU when bus_set_iommu() is called. In order
697 	 * not to rely on global variables to track the IOMMU instance, we
698 	 * set it here so that it can be looked up from the .add_device()
699 	 * callback via the IOMMU device's .drvdata field.
700 	 */
701 	mc->smmu = smmu;
702 
703 	size = BITS_TO_LONGS(soc->num_asids) * sizeof(long);
704 
705 	smmu->asids = devm_kzalloc(dev, size, GFP_KERNEL);
706 	if (!smmu->asids)
707 		return ERR_PTR(-ENOMEM);
708 
709 	mutex_init(&smmu->lock);
710 
711 	smmu->regs = mc->regs;
712 	smmu->soc = soc;
713 	smmu->dev = dev;
714 	smmu->mc = mc;
715 
716 	smmu->pfn_mask = BIT_MASK(mc->soc->num_address_bits - PAGE_SHIFT) - 1;
717 	dev_dbg(dev, "address bits: %u, PFN mask: %#lx\n",
718 		mc->soc->num_address_bits, smmu->pfn_mask);
719 
720 	value = SMMU_PTC_CONFIG_ENABLE | SMMU_PTC_CONFIG_INDEX_MAP(0x3f);
721 
722 	if (soc->supports_request_limit)
723 		value |= SMMU_PTC_CONFIG_REQ_LIMIT(8);
724 
725 	smmu_writel(smmu, value, SMMU_PTC_CONFIG);
726 
727 	value = SMMU_TLB_CONFIG_HIT_UNDER_MISS |
728 		SMMU_TLB_CONFIG_ACTIVE_LINES(0x20);
729 
730 	if (soc->supports_round_robin_arbitration)
731 		value |= SMMU_TLB_CONFIG_ROUND_ROBIN_ARBITRATION;
732 
733 	smmu_writel(smmu, value, SMMU_TLB_CONFIG);
734 
735 	smmu_flush_ptc(smmu, NULL, 0);
736 	smmu_flush_tlb(smmu);
737 	smmu_writel(smmu, SMMU_CONFIG_ENABLE, SMMU_CONFIG);
738 	smmu_flush(smmu);
739 
740 	tegra_smmu_ahb_enable();
741 
742 	err = bus_set_iommu(&platform_bus_type, &tegra_smmu_ops);
743 	if (err < 0)
744 		return ERR_PTR(err);
745 
746 	return smmu;
747 }
748