xref: /linux/drivers/iommu/tegra-smmu.c (revision 93d90ad708b8da6efc0e487b66111aa9db7f70c7)
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/err.h>
10 #include <linux/iommu.h>
11 #include <linux/kernel.h>
12 #include <linux/of.h>
13 #include <linux/of_device.h>
14 #include <linux/platform_device.h>
15 #include <linux/slab.h>
16 
17 #include <soc/tegra/ahb.h>
18 #include <soc/tegra/mc.h>
19 
20 struct tegra_smmu {
21 	void __iomem *regs;
22 	struct device *dev;
23 
24 	struct tegra_mc *mc;
25 	const struct tegra_smmu_soc *soc;
26 
27 	unsigned long *asids;
28 	struct mutex lock;
29 
30 	struct list_head list;
31 };
32 
33 struct tegra_smmu_as {
34 	struct iommu_domain *domain;
35 	struct tegra_smmu *smmu;
36 	unsigned int use_count;
37 	struct page *count;
38 	struct page *pd;
39 	unsigned id;
40 	u32 attr;
41 };
42 
43 static inline void smmu_writel(struct tegra_smmu *smmu, u32 value,
44 			       unsigned long offset)
45 {
46 	writel(value, smmu->regs + offset);
47 }
48 
49 static inline u32 smmu_readl(struct tegra_smmu *smmu, unsigned long offset)
50 {
51 	return readl(smmu->regs + offset);
52 }
53 
54 #define SMMU_CONFIG 0x010
55 #define  SMMU_CONFIG_ENABLE (1 << 0)
56 
57 #define SMMU_TLB_CONFIG 0x14
58 #define  SMMU_TLB_CONFIG_HIT_UNDER_MISS (1 << 29)
59 #define  SMMU_TLB_CONFIG_ROUND_ROBIN_ARBITRATION (1 << 28)
60 #define  SMMU_TLB_CONFIG_ACTIVE_LINES(x) ((x) & 0x3f)
61 
62 #define SMMU_PTC_CONFIG 0x18
63 #define  SMMU_PTC_CONFIG_ENABLE (1 << 29)
64 #define  SMMU_PTC_CONFIG_REQ_LIMIT(x) (((x) & 0x0f) << 24)
65 #define  SMMU_PTC_CONFIG_INDEX_MAP(x) ((x) & 0x3f)
66 
67 #define SMMU_PTB_ASID 0x01c
68 #define  SMMU_PTB_ASID_VALUE(x) ((x) & 0x7f)
69 
70 #define SMMU_PTB_DATA 0x020
71 #define  SMMU_PTB_DATA_VALUE(page, attr) (page_to_phys(page) >> 12 | (attr))
72 
73 #define SMMU_MK_PDE(page, attr) (page_to_phys(page) >> SMMU_PTE_SHIFT | (attr))
74 
75 #define SMMU_TLB_FLUSH 0x030
76 #define  SMMU_TLB_FLUSH_VA_MATCH_ALL     (0 << 0)
77 #define  SMMU_TLB_FLUSH_VA_MATCH_SECTION (2 << 0)
78 #define  SMMU_TLB_FLUSH_VA_MATCH_GROUP   (3 << 0)
79 #define  SMMU_TLB_FLUSH_ASID(x)          (((x) & 0x7f) << 24)
80 #define  SMMU_TLB_FLUSH_VA_SECTION(addr) ((((addr) & 0xffc00000) >> 12) | \
81 					  SMMU_TLB_FLUSH_VA_MATCH_SECTION)
82 #define  SMMU_TLB_FLUSH_VA_GROUP(addr)   ((((addr) & 0xffffc000) >> 12) | \
83 					  SMMU_TLB_FLUSH_VA_MATCH_GROUP)
84 #define  SMMU_TLB_FLUSH_ASID_MATCH       (1 << 31)
85 
86 #define SMMU_PTC_FLUSH 0x034
87 #define  SMMU_PTC_FLUSH_TYPE_ALL (0 << 0)
88 #define  SMMU_PTC_FLUSH_TYPE_ADR (1 << 0)
89 
90 #define SMMU_PTC_FLUSH_HI 0x9b8
91 #define  SMMU_PTC_FLUSH_HI_MASK 0x3
92 
93 /* per-SWGROUP SMMU_*_ASID register */
94 #define SMMU_ASID_ENABLE (1 << 31)
95 #define SMMU_ASID_MASK 0x7f
96 #define SMMU_ASID_VALUE(x) ((x) & SMMU_ASID_MASK)
97 
98 /* page table definitions */
99 #define SMMU_NUM_PDE 1024
100 #define SMMU_NUM_PTE 1024
101 
102 #define SMMU_SIZE_PD (SMMU_NUM_PDE * 4)
103 #define SMMU_SIZE_PT (SMMU_NUM_PTE * 4)
104 
105 #define SMMU_PDE_SHIFT 22
106 #define SMMU_PTE_SHIFT 12
107 
108 #define SMMU_PFN_MASK 0x000fffff
109 
110 #define SMMU_PD_READABLE	(1 << 31)
111 #define SMMU_PD_WRITABLE	(1 << 30)
112 #define SMMU_PD_NONSECURE	(1 << 29)
113 
114 #define SMMU_PDE_READABLE	(1 << 31)
115 #define SMMU_PDE_WRITABLE	(1 << 30)
116 #define SMMU_PDE_NONSECURE	(1 << 29)
117 #define SMMU_PDE_NEXT		(1 << 28)
118 
119 #define SMMU_PTE_READABLE	(1 << 31)
120 #define SMMU_PTE_WRITABLE	(1 << 30)
121 #define SMMU_PTE_NONSECURE	(1 << 29)
122 
123 #define SMMU_PDE_ATTR		(SMMU_PDE_READABLE | SMMU_PDE_WRITABLE | \
124 				 SMMU_PDE_NONSECURE)
125 #define SMMU_PTE_ATTR		(SMMU_PTE_READABLE | SMMU_PTE_WRITABLE | \
126 				 SMMU_PTE_NONSECURE)
127 
128 static inline void smmu_flush_ptc(struct tegra_smmu *smmu, struct page *page,
129 				  unsigned long offset)
130 {
131 	phys_addr_t phys = page ? page_to_phys(page) : 0;
132 	u32 value;
133 
134 	if (page) {
135 		offset &= ~(smmu->mc->soc->atom_size - 1);
136 
137 		if (smmu->mc->soc->num_address_bits > 32) {
138 #ifdef CONFIG_PHYS_ADDR_T_64BIT
139 			value = (phys >> 32) & SMMU_PTC_FLUSH_HI_MASK;
140 #else
141 			value = 0;
142 #endif
143 			smmu_writel(smmu, value, SMMU_PTC_FLUSH_HI);
144 		}
145 
146 		value = (phys + offset) | SMMU_PTC_FLUSH_TYPE_ADR;
147 	} else {
148 		value = SMMU_PTC_FLUSH_TYPE_ALL;
149 	}
150 
151 	smmu_writel(smmu, value, SMMU_PTC_FLUSH);
152 }
153 
154 static inline void smmu_flush_tlb(struct tegra_smmu *smmu)
155 {
156 	smmu_writel(smmu, SMMU_TLB_FLUSH_VA_MATCH_ALL, SMMU_TLB_FLUSH);
157 }
158 
159 static inline void smmu_flush_tlb_asid(struct tegra_smmu *smmu,
160 				       unsigned long asid)
161 {
162 	u32 value;
163 
164 	value = SMMU_TLB_FLUSH_ASID_MATCH | SMMU_TLB_FLUSH_ASID(asid) |
165 		SMMU_TLB_FLUSH_VA_MATCH_ALL;
166 	smmu_writel(smmu, value, SMMU_TLB_FLUSH);
167 }
168 
169 static inline void smmu_flush_tlb_section(struct tegra_smmu *smmu,
170 					  unsigned long asid,
171 					  unsigned long iova)
172 {
173 	u32 value;
174 
175 	value = SMMU_TLB_FLUSH_ASID_MATCH | SMMU_TLB_FLUSH_ASID(asid) |
176 		SMMU_TLB_FLUSH_VA_SECTION(iova);
177 	smmu_writel(smmu, value, SMMU_TLB_FLUSH);
178 }
179 
180 static inline void smmu_flush_tlb_group(struct tegra_smmu *smmu,
181 					unsigned long asid,
182 					unsigned long iova)
183 {
184 	u32 value;
185 
186 	value = SMMU_TLB_FLUSH_ASID_MATCH | SMMU_TLB_FLUSH_ASID(asid) |
187 		SMMU_TLB_FLUSH_VA_GROUP(iova);
188 	smmu_writel(smmu, value, SMMU_TLB_FLUSH);
189 }
190 
191 static inline void smmu_flush(struct tegra_smmu *smmu)
192 {
193 	smmu_readl(smmu, SMMU_CONFIG);
194 }
195 
196 static int tegra_smmu_alloc_asid(struct tegra_smmu *smmu, unsigned int *idp)
197 {
198 	unsigned long id;
199 
200 	mutex_lock(&smmu->lock);
201 
202 	id = find_first_zero_bit(smmu->asids, smmu->soc->num_asids);
203 	if (id >= smmu->soc->num_asids) {
204 		mutex_unlock(&smmu->lock);
205 		return -ENOSPC;
206 	}
207 
208 	set_bit(id, smmu->asids);
209 	*idp = id;
210 
211 	mutex_unlock(&smmu->lock);
212 	return 0;
213 }
214 
215 static void tegra_smmu_free_asid(struct tegra_smmu *smmu, unsigned int id)
216 {
217 	mutex_lock(&smmu->lock);
218 	clear_bit(id, smmu->asids);
219 	mutex_unlock(&smmu->lock);
220 }
221 
222 static bool tegra_smmu_capable(enum iommu_cap cap)
223 {
224 	return false;
225 }
226 
227 static int tegra_smmu_domain_init(struct iommu_domain *domain)
228 {
229 	struct tegra_smmu_as *as;
230 	unsigned int i;
231 	uint32_t *pd;
232 
233 	as = kzalloc(sizeof(*as), GFP_KERNEL);
234 	if (!as)
235 		return -ENOMEM;
236 
237 	as->attr = SMMU_PD_READABLE | SMMU_PD_WRITABLE | SMMU_PD_NONSECURE;
238 	as->domain = domain;
239 
240 	as->pd = alloc_page(GFP_KERNEL | __GFP_DMA);
241 	if (!as->pd) {
242 		kfree(as);
243 		return -ENOMEM;
244 	}
245 
246 	as->count = alloc_page(GFP_KERNEL);
247 	if (!as->count) {
248 		__free_page(as->pd);
249 		kfree(as);
250 		return -ENOMEM;
251 	}
252 
253 	/* clear PDEs */
254 	pd = page_address(as->pd);
255 	SetPageReserved(as->pd);
256 
257 	for (i = 0; i < SMMU_NUM_PDE; i++)
258 		pd[i] = 0;
259 
260 	/* clear PDE usage counters */
261 	pd = page_address(as->count);
262 	SetPageReserved(as->count);
263 
264 	for (i = 0; i < SMMU_NUM_PDE; i++)
265 		pd[i] = 0;
266 
267 	domain->priv = as;
268 
269 	return 0;
270 }
271 
272 static void tegra_smmu_domain_destroy(struct iommu_domain *domain)
273 {
274 	struct tegra_smmu_as *as = domain->priv;
275 
276 	/* TODO: free page directory and page tables */
277 	ClearPageReserved(as->pd);
278 
279 	kfree(as);
280 }
281 
282 static const struct tegra_smmu_swgroup *
283 tegra_smmu_find_swgroup(struct tegra_smmu *smmu, unsigned int swgroup)
284 {
285 	const struct tegra_smmu_swgroup *group = NULL;
286 	unsigned int i;
287 
288 	for (i = 0; i < smmu->soc->num_swgroups; i++) {
289 		if (smmu->soc->swgroups[i].swgroup == swgroup) {
290 			group = &smmu->soc->swgroups[i];
291 			break;
292 		}
293 	}
294 
295 	return group;
296 }
297 
298 static void tegra_smmu_enable(struct tegra_smmu *smmu, unsigned int swgroup,
299 			      unsigned int asid)
300 {
301 	const struct tegra_smmu_swgroup *group;
302 	unsigned int i;
303 	u32 value;
304 
305 	for (i = 0; i < smmu->soc->num_clients; i++) {
306 		const struct tegra_mc_client *client = &smmu->soc->clients[i];
307 
308 		if (client->swgroup != swgroup)
309 			continue;
310 
311 		value = smmu_readl(smmu, client->smmu.reg);
312 		value |= BIT(client->smmu.bit);
313 		smmu_writel(smmu, value, client->smmu.reg);
314 	}
315 
316 	group = tegra_smmu_find_swgroup(smmu, swgroup);
317 	if (group) {
318 		value = smmu_readl(smmu, group->reg);
319 		value &= ~SMMU_ASID_MASK;
320 		value |= SMMU_ASID_VALUE(asid);
321 		value |= SMMU_ASID_ENABLE;
322 		smmu_writel(smmu, value, group->reg);
323 	}
324 }
325 
326 static void tegra_smmu_disable(struct tegra_smmu *smmu, unsigned int swgroup,
327 			       unsigned int asid)
328 {
329 	const struct tegra_smmu_swgroup *group;
330 	unsigned int i;
331 	u32 value;
332 
333 	group = tegra_smmu_find_swgroup(smmu, swgroup);
334 	if (group) {
335 		value = smmu_readl(smmu, group->reg);
336 		value &= ~SMMU_ASID_MASK;
337 		value |= SMMU_ASID_VALUE(asid);
338 		value &= ~SMMU_ASID_ENABLE;
339 		smmu_writel(smmu, value, group->reg);
340 	}
341 
342 	for (i = 0; i < smmu->soc->num_clients; i++) {
343 		const struct tegra_mc_client *client = &smmu->soc->clients[i];
344 
345 		if (client->swgroup != swgroup)
346 			continue;
347 
348 		value = smmu_readl(smmu, client->smmu.reg);
349 		value &= ~BIT(client->smmu.bit);
350 		smmu_writel(smmu, value, client->smmu.reg);
351 	}
352 }
353 
354 static int tegra_smmu_as_prepare(struct tegra_smmu *smmu,
355 				 struct tegra_smmu_as *as)
356 {
357 	u32 value;
358 	int err;
359 
360 	if (as->use_count > 0) {
361 		as->use_count++;
362 		return 0;
363 	}
364 
365 	err = tegra_smmu_alloc_asid(smmu, &as->id);
366 	if (err < 0)
367 		return err;
368 
369 	smmu->soc->ops->flush_dcache(as->pd, 0, SMMU_SIZE_PD);
370 	smmu_flush_ptc(smmu, as->pd, 0);
371 	smmu_flush_tlb_asid(smmu, as->id);
372 
373 	smmu_writel(smmu, as->id & 0x7f, SMMU_PTB_ASID);
374 	value = SMMU_PTB_DATA_VALUE(as->pd, as->attr);
375 	smmu_writel(smmu, value, SMMU_PTB_DATA);
376 	smmu_flush(smmu);
377 
378 	as->smmu = smmu;
379 	as->use_count++;
380 
381 	return 0;
382 }
383 
384 static void tegra_smmu_as_unprepare(struct tegra_smmu *smmu,
385 				    struct tegra_smmu_as *as)
386 {
387 	if (--as->use_count > 0)
388 		return;
389 
390 	tegra_smmu_free_asid(smmu, as->id);
391 	as->smmu = NULL;
392 }
393 
394 static int tegra_smmu_attach_dev(struct iommu_domain *domain,
395 				 struct device *dev)
396 {
397 	struct tegra_smmu *smmu = dev->archdata.iommu;
398 	struct tegra_smmu_as *as = domain->priv;
399 	struct device_node *np = dev->of_node;
400 	struct of_phandle_args args;
401 	unsigned int index = 0;
402 	int err = 0;
403 
404 	while (!of_parse_phandle_with_args(np, "iommus", "#iommu-cells", index,
405 					   &args)) {
406 		unsigned int swgroup = args.args[0];
407 
408 		if (args.np != smmu->dev->of_node) {
409 			of_node_put(args.np);
410 			continue;
411 		}
412 
413 		of_node_put(args.np);
414 
415 		err = tegra_smmu_as_prepare(smmu, as);
416 		if (err < 0)
417 			return err;
418 
419 		tegra_smmu_enable(smmu, swgroup, as->id);
420 		index++;
421 	}
422 
423 	if (index == 0)
424 		return -ENODEV;
425 
426 	return 0;
427 }
428 
429 static void tegra_smmu_detach_dev(struct iommu_domain *domain, struct device *dev)
430 {
431 	struct tegra_smmu_as *as = domain->priv;
432 	struct device_node *np = dev->of_node;
433 	struct tegra_smmu *smmu = as->smmu;
434 	struct of_phandle_args args;
435 	unsigned int index = 0;
436 
437 	while (!of_parse_phandle_with_args(np, "iommus", "#iommu-cells", index,
438 					   &args)) {
439 		unsigned int swgroup = args.args[0];
440 
441 		if (args.np != smmu->dev->of_node) {
442 			of_node_put(args.np);
443 			continue;
444 		}
445 
446 		of_node_put(args.np);
447 
448 		tegra_smmu_disable(smmu, swgroup, as->id);
449 		tegra_smmu_as_unprepare(smmu, as);
450 		index++;
451 	}
452 }
453 
454 static u32 *as_get_pte(struct tegra_smmu_as *as, dma_addr_t iova,
455 		       struct page **pagep)
456 {
457 	u32 *pd = page_address(as->pd), *pt, *count;
458 	u32 pde = (iova >> SMMU_PDE_SHIFT) & 0x3ff;
459 	u32 pte = (iova >> SMMU_PTE_SHIFT) & 0x3ff;
460 	struct tegra_smmu *smmu = as->smmu;
461 	struct page *page;
462 	unsigned int i;
463 
464 	if (pd[pde] == 0) {
465 		page = alloc_page(GFP_KERNEL | __GFP_DMA);
466 		if (!page)
467 			return NULL;
468 
469 		pt = page_address(page);
470 		SetPageReserved(page);
471 
472 		for (i = 0; i < SMMU_NUM_PTE; i++)
473 			pt[i] = 0;
474 
475 		smmu->soc->ops->flush_dcache(page, 0, SMMU_SIZE_PT);
476 
477 		pd[pde] = SMMU_MK_PDE(page, SMMU_PDE_ATTR | SMMU_PDE_NEXT);
478 
479 		smmu->soc->ops->flush_dcache(as->pd, pde << 2, 4);
480 		smmu_flush_ptc(smmu, as->pd, pde << 2);
481 		smmu_flush_tlb_section(smmu, as->id, iova);
482 		smmu_flush(smmu);
483 	} else {
484 		page = pfn_to_page(pd[pde] & SMMU_PFN_MASK);
485 		pt = page_address(page);
486 	}
487 
488 	*pagep = page;
489 
490 	/* Keep track of entries in this page table. */
491 	count = page_address(as->count);
492 	if (pt[pte] == 0)
493 		count[pde]++;
494 
495 	return &pt[pte];
496 }
497 
498 static void as_put_pte(struct tegra_smmu_as *as, dma_addr_t iova)
499 {
500 	u32 pde = (iova >> SMMU_PDE_SHIFT) & 0x3ff;
501 	u32 pte = (iova >> SMMU_PTE_SHIFT) & 0x3ff;
502 	u32 *count = page_address(as->count);
503 	u32 *pd = page_address(as->pd), *pt;
504 	struct page *page;
505 
506 	page = pfn_to_page(pd[pde] & SMMU_PFN_MASK);
507 	pt = page_address(page);
508 
509 	/*
510 	 * When no entries in this page table are used anymore, return the
511 	 * memory page to the system.
512 	 */
513 	if (pt[pte] != 0) {
514 		if (--count[pde] == 0) {
515 			ClearPageReserved(page);
516 			__free_page(page);
517 			pd[pde] = 0;
518 		}
519 
520 		pt[pte] = 0;
521 	}
522 }
523 
524 static int tegra_smmu_map(struct iommu_domain *domain, unsigned long iova,
525 			  phys_addr_t paddr, size_t size, int prot)
526 {
527 	struct tegra_smmu_as *as = domain->priv;
528 	struct tegra_smmu *smmu = as->smmu;
529 	unsigned long offset;
530 	struct page *page;
531 	u32 *pte;
532 
533 	pte = as_get_pte(as, iova, &page);
534 	if (!pte)
535 		return -ENOMEM;
536 
537 	*pte = __phys_to_pfn(paddr) | SMMU_PTE_ATTR;
538 	offset = offset_in_page(pte);
539 
540 	smmu->soc->ops->flush_dcache(page, offset, 4);
541 	smmu_flush_ptc(smmu, page, offset);
542 	smmu_flush_tlb_group(smmu, as->id, iova);
543 	smmu_flush(smmu);
544 
545 	return 0;
546 }
547 
548 static size_t tegra_smmu_unmap(struct iommu_domain *domain, unsigned long iova,
549 			       size_t size)
550 {
551 	struct tegra_smmu_as *as = domain->priv;
552 	struct tegra_smmu *smmu = as->smmu;
553 	unsigned long offset;
554 	struct page *page;
555 	u32 *pte;
556 
557 	pte = as_get_pte(as, iova, &page);
558 	if (!pte)
559 		return 0;
560 
561 	offset = offset_in_page(pte);
562 	as_put_pte(as, iova);
563 
564 	smmu->soc->ops->flush_dcache(page, offset, 4);
565 	smmu_flush_ptc(smmu, page, offset);
566 	smmu_flush_tlb_group(smmu, as->id, iova);
567 	smmu_flush(smmu);
568 
569 	return size;
570 }
571 
572 static phys_addr_t tegra_smmu_iova_to_phys(struct iommu_domain *domain,
573 					   dma_addr_t iova)
574 {
575 	struct tegra_smmu_as *as = domain->priv;
576 	struct page *page;
577 	unsigned long pfn;
578 	u32 *pte;
579 
580 	pte = as_get_pte(as, iova, &page);
581 	pfn = *pte & SMMU_PFN_MASK;
582 
583 	return PFN_PHYS(pfn);
584 }
585 
586 static struct tegra_smmu *tegra_smmu_find(struct device_node *np)
587 {
588 	struct platform_device *pdev;
589 	struct tegra_mc *mc;
590 
591 	pdev = of_find_device_by_node(np);
592 	if (!pdev)
593 		return NULL;
594 
595 	mc = platform_get_drvdata(pdev);
596 	if (!mc)
597 		return NULL;
598 
599 	return mc->smmu;
600 }
601 
602 static int tegra_smmu_add_device(struct device *dev)
603 {
604 	struct device_node *np = dev->of_node;
605 	struct of_phandle_args args;
606 	unsigned int index = 0;
607 
608 	while (of_parse_phandle_with_args(np, "iommus", "#iommu-cells", index,
609 					  &args) == 0) {
610 		struct tegra_smmu *smmu;
611 
612 		smmu = tegra_smmu_find(args.np);
613 		if (smmu) {
614 			/*
615 			 * Only a single IOMMU master interface is currently
616 			 * supported by the Linux kernel, so abort after the
617 			 * first match.
618 			 */
619 			dev->archdata.iommu = smmu;
620 			break;
621 		}
622 
623 		index++;
624 	}
625 
626 	return 0;
627 }
628 
629 static void tegra_smmu_remove_device(struct device *dev)
630 {
631 	dev->archdata.iommu = NULL;
632 }
633 
634 static const struct iommu_ops tegra_smmu_ops = {
635 	.capable = tegra_smmu_capable,
636 	.domain_init = tegra_smmu_domain_init,
637 	.domain_destroy = tegra_smmu_domain_destroy,
638 	.attach_dev = tegra_smmu_attach_dev,
639 	.detach_dev = tegra_smmu_detach_dev,
640 	.add_device = tegra_smmu_add_device,
641 	.remove_device = tegra_smmu_remove_device,
642 	.map = tegra_smmu_map,
643 	.unmap = tegra_smmu_unmap,
644 	.map_sg = default_iommu_map_sg,
645 	.iova_to_phys = tegra_smmu_iova_to_phys,
646 
647 	.pgsize_bitmap = SZ_4K,
648 };
649 
650 static void tegra_smmu_ahb_enable(void)
651 {
652 	static const struct of_device_id ahb_match[] = {
653 		{ .compatible = "nvidia,tegra30-ahb", },
654 		{ }
655 	};
656 	struct device_node *ahb;
657 
658 	ahb = of_find_matching_node(NULL, ahb_match);
659 	if (ahb) {
660 		tegra_ahb_enable_smmu(ahb);
661 		of_node_put(ahb);
662 	}
663 }
664 
665 struct tegra_smmu *tegra_smmu_probe(struct device *dev,
666 				    const struct tegra_smmu_soc *soc,
667 				    struct tegra_mc *mc)
668 {
669 	struct tegra_smmu *smmu;
670 	size_t size;
671 	u32 value;
672 	int err;
673 
674 	/* This can happen on Tegra20 which doesn't have an SMMU */
675 	if (!soc)
676 		return NULL;
677 
678 	smmu = devm_kzalloc(dev, sizeof(*smmu), GFP_KERNEL);
679 	if (!smmu)
680 		return ERR_PTR(-ENOMEM);
681 
682 	/*
683 	 * This is a bit of a hack. Ideally we'd want to simply return this
684 	 * value. However the IOMMU registration process will attempt to add
685 	 * all devices to the IOMMU when bus_set_iommu() is called. In order
686 	 * not to rely on global variables to track the IOMMU instance, we
687 	 * set it here so that it can be looked up from the .add_device()
688 	 * callback via the IOMMU device's .drvdata field.
689 	 */
690 	mc->smmu = smmu;
691 
692 	size = BITS_TO_LONGS(soc->num_asids) * sizeof(long);
693 
694 	smmu->asids = devm_kzalloc(dev, size, GFP_KERNEL);
695 	if (!smmu->asids)
696 		return ERR_PTR(-ENOMEM);
697 
698 	mutex_init(&smmu->lock);
699 
700 	smmu->regs = mc->regs;
701 	smmu->soc = soc;
702 	smmu->dev = dev;
703 	smmu->mc = mc;
704 
705 	value = SMMU_PTC_CONFIG_ENABLE | SMMU_PTC_CONFIG_INDEX_MAP(0x3f);
706 
707 	if (soc->supports_request_limit)
708 		value |= SMMU_PTC_CONFIG_REQ_LIMIT(8);
709 
710 	smmu_writel(smmu, value, SMMU_PTC_CONFIG);
711 
712 	value = SMMU_TLB_CONFIG_HIT_UNDER_MISS |
713 		SMMU_TLB_CONFIG_ACTIVE_LINES(0x20);
714 
715 	if (soc->supports_round_robin_arbitration)
716 		value |= SMMU_TLB_CONFIG_ROUND_ROBIN_ARBITRATION;
717 
718 	smmu_writel(smmu, value, SMMU_TLB_CONFIG);
719 
720 	smmu_flush_ptc(smmu, NULL, 0);
721 	smmu_flush_tlb(smmu);
722 	smmu_writel(smmu, SMMU_CONFIG_ENABLE, SMMU_CONFIG);
723 	smmu_flush(smmu);
724 
725 	tegra_smmu_ahb_enable();
726 
727 	err = bus_set_iommu(&platform_bus_type, &tegra_smmu_ops);
728 	if (err < 0)
729 		return ERR_PTR(err);
730 
731 	return smmu;
732 }
733