1 /*
2  * Copyright © 2010 Daniel Vetter
3  *
4  * Permission is hereby granted, free of charge, to any person obtaining a
5  * copy of this software and associated documentation files (the "Software"),
6  * to deal in the Software without restriction, including without limitation
7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8  * and/or sell copies of the Software, and to permit persons to whom the
9  * Software is furnished to do so, subject to the following conditions:
10  *
11  * The above copyright notice and this permission notice (including the next
12  * paragraph) shall be included in all copies or substantial portions of the
13  * Software.
14  *
15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
18  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
20  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
21  * IN THE SOFTWARE.
22  *
23  */
24 
25 #include <drm/drmP.h>
26 #include <drm/i915_drm.h>
27 #include "i915_drv.h"
28 #include "i915_trace.h"
29 #include "intel_drv.h"
30 
31 typedef uint32_t gtt_pte_t;
32 
33 /* PPGTT stuff */
34 #define GEN6_GTT_ADDR_ENCODE(addr)	((addr) | (((addr) >> 28) & 0xff0))
35 
36 #define GEN6_PDE_VALID			(1 << 0)
37 /* gen6+ has bit 11-4 for physical addr bit 39-32 */
38 #define GEN6_PDE_ADDR_ENCODE(addr)	GEN6_GTT_ADDR_ENCODE(addr)
39 
40 #define GEN6_PTE_VALID			(1 << 0)
41 #define GEN6_PTE_UNCACHED		(1 << 1)
42 #define HSW_PTE_UNCACHED		(0)
43 #define GEN6_PTE_CACHE_LLC		(2 << 1)
44 #define GEN6_PTE_CACHE_LLC_MLC		(3 << 1)
45 #define GEN6_PTE_ADDR_ENCODE(addr)	GEN6_GTT_ADDR_ENCODE(addr)
46 
47 static inline gtt_pte_t pte_encode(struct drm_device *dev,
48 				   dma_addr_t addr,
49 				   enum i915_cache_level level)
50 {
51 	gtt_pte_t pte = GEN6_PTE_VALID;
52 	pte |= GEN6_PTE_ADDR_ENCODE(addr);
53 
54 	switch (level) {
55 	case I915_CACHE_LLC_MLC:
56 		/* Haswell doesn't set L3 this way */
57 		if (IS_HASWELL(dev))
58 			pte |= GEN6_PTE_CACHE_LLC;
59 		else
60 			pte |= GEN6_PTE_CACHE_LLC_MLC;
61 		break;
62 	case I915_CACHE_LLC:
63 		pte |= GEN6_PTE_CACHE_LLC;
64 		break;
65 	case I915_CACHE_NONE:
66 		if (IS_HASWELL(dev))
67 			pte |= HSW_PTE_UNCACHED;
68 		else
69 			pte |= GEN6_PTE_UNCACHED;
70 		break;
71 	default:
72 		BUG();
73 	}
74 
75 
76 	return pte;
77 }
78 
79 /* PPGTT support for Sandybdrige/Gen6 and later */
80 static void i915_ppgtt_clear_range(struct i915_hw_ppgtt *ppgtt,
81 				   unsigned first_entry,
82 				   unsigned num_entries)
83 {
84 	gtt_pte_t *pt_vaddr;
85 	gtt_pte_t scratch_pte;
86 	unsigned act_pd = first_entry / I915_PPGTT_PT_ENTRIES;
87 	unsigned first_pte = first_entry % I915_PPGTT_PT_ENTRIES;
88 	unsigned last_pte, i;
89 
90 	scratch_pte = pte_encode(ppgtt->dev, ppgtt->scratch_page_dma_addr,
91 				 I915_CACHE_LLC);
92 
93 	while (num_entries) {
94 		last_pte = first_pte + num_entries;
95 		if (last_pte > I915_PPGTT_PT_ENTRIES)
96 			last_pte = I915_PPGTT_PT_ENTRIES;
97 
98 		pt_vaddr = kmap_atomic(ppgtt->pt_pages[act_pd]);
99 
100 		for (i = first_pte; i < last_pte; i++)
101 			pt_vaddr[i] = scratch_pte;
102 
103 		kunmap_atomic(pt_vaddr);
104 
105 		num_entries -= last_pte - first_pte;
106 		first_pte = 0;
107 		act_pd++;
108 	}
109 }
110 
111 int i915_gem_init_aliasing_ppgtt(struct drm_device *dev)
112 {
113 	struct drm_i915_private *dev_priv = dev->dev_private;
114 	struct i915_hw_ppgtt *ppgtt;
115 	unsigned first_pd_entry_in_global_pt;
116 	int i;
117 	int ret = -ENOMEM;
118 
119 	/* ppgtt PDEs reside in the global gtt pagetable, which has 512*1024
120 	 * entries. For aliasing ppgtt support we just steal them at the end for
121 	 * now. */
122 	first_pd_entry_in_global_pt = dev_priv->mm.gtt->gtt_total_entries - I915_PPGTT_PD_ENTRIES;
123 
124 	ppgtt = kzalloc(sizeof(*ppgtt), GFP_KERNEL);
125 	if (!ppgtt)
126 		return ret;
127 
128 	ppgtt->dev = dev;
129 	ppgtt->num_pd_entries = I915_PPGTT_PD_ENTRIES;
130 	ppgtt->pt_pages = kzalloc(sizeof(struct page *)*ppgtt->num_pd_entries,
131 				  GFP_KERNEL);
132 	if (!ppgtt->pt_pages)
133 		goto err_ppgtt;
134 
135 	for (i = 0; i < ppgtt->num_pd_entries; i++) {
136 		ppgtt->pt_pages[i] = alloc_page(GFP_KERNEL);
137 		if (!ppgtt->pt_pages[i])
138 			goto err_pt_alloc;
139 	}
140 
141 	if (dev_priv->mm.gtt->needs_dmar) {
142 		ppgtt->pt_dma_addr = kzalloc(sizeof(dma_addr_t)
143 						*ppgtt->num_pd_entries,
144 					     GFP_KERNEL);
145 		if (!ppgtt->pt_dma_addr)
146 			goto err_pt_alloc;
147 
148 		for (i = 0; i < ppgtt->num_pd_entries; i++) {
149 			dma_addr_t pt_addr;
150 
151 			pt_addr = pci_map_page(dev->pdev, ppgtt->pt_pages[i],
152 					       0, 4096,
153 					       PCI_DMA_BIDIRECTIONAL);
154 
155 			if (pci_dma_mapping_error(dev->pdev,
156 						  pt_addr)) {
157 				ret = -EIO;
158 				goto err_pd_pin;
159 
160 			}
161 			ppgtt->pt_dma_addr[i] = pt_addr;
162 		}
163 	}
164 
165 	ppgtt->scratch_page_dma_addr = dev_priv->mm.gtt->scratch_page_dma;
166 
167 	i915_ppgtt_clear_range(ppgtt, 0,
168 			       ppgtt->num_pd_entries*I915_PPGTT_PT_ENTRIES);
169 
170 	ppgtt->pd_offset = (first_pd_entry_in_global_pt)*sizeof(gtt_pte_t);
171 
172 	dev_priv->mm.aliasing_ppgtt = ppgtt;
173 
174 	return 0;
175 
176 err_pd_pin:
177 	if (ppgtt->pt_dma_addr) {
178 		for (i--; i >= 0; i--)
179 			pci_unmap_page(dev->pdev, ppgtt->pt_dma_addr[i],
180 				       4096, PCI_DMA_BIDIRECTIONAL);
181 	}
182 err_pt_alloc:
183 	kfree(ppgtt->pt_dma_addr);
184 	for (i = 0; i < ppgtt->num_pd_entries; i++) {
185 		if (ppgtt->pt_pages[i])
186 			__free_page(ppgtt->pt_pages[i]);
187 	}
188 	kfree(ppgtt->pt_pages);
189 err_ppgtt:
190 	kfree(ppgtt);
191 
192 	return ret;
193 }
194 
195 void i915_gem_cleanup_aliasing_ppgtt(struct drm_device *dev)
196 {
197 	struct drm_i915_private *dev_priv = dev->dev_private;
198 	struct i915_hw_ppgtt *ppgtt = dev_priv->mm.aliasing_ppgtt;
199 	int i;
200 
201 	if (!ppgtt)
202 		return;
203 
204 	if (ppgtt->pt_dma_addr) {
205 		for (i = 0; i < ppgtt->num_pd_entries; i++)
206 			pci_unmap_page(dev->pdev, ppgtt->pt_dma_addr[i],
207 				       4096, PCI_DMA_BIDIRECTIONAL);
208 	}
209 
210 	kfree(ppgtt->pt_dma_addr);
211 	for (i = 0; i < ppgtt->num_pd_entries; i++)
212 		__free_page(ppgtt->pt_pages[i]);
213 	kfree(ppgtt->pt_pages);
214 	kfree(ppgtt);
215 }
216 
217 static void i915_ppgtt_insert_sg_entries(struct i915_hw_ppgtt *ppgtt,
218 					 const struct sg_table *pages,
219 					 unsigned first_entry,
220 					 enum i915_cache_level cache_level)
221 {
222 	gtt_pte_t *pt_vaddr;
223 	unsigned act_pd = first_entry / I915_PPGTT_PT_ENTRIES;
224 	unsigned first_pte = first_entry % I915_PPGTT_PT_ENTRIES;
225 	unsigned i, j, m, segment_len;
226 	dma_addr_t page_addr;
227 	struct scatterlist *sg;
228 
229 	/* init sg walking */
230 	sg = pages->sgl;
231 	i = 0;
232 	segment_len = sg_dma_len(sg) >> PAGE_SHIFT;
233 	m = 0;
234 
235 	while (i < pages->nents) {
236 		pt_vaddr = kmap_atomic(ppgtt->pt_pages[act_pd]);
237 
238 		for (j = first_pte; j < I915_PPGTT_PT_ENTRIES; j++) {
239 			page_addr = sg_dma_address(sg) + (m << PAGE_SHIFT);
240 			pt_vaddr[j] = pte_encode(ppgtt->dev, page_addr,
241 						 cache_level);
242 
243 			/* grab the next page */
244 			if (++m == segment_len) {
245 				if (++i == pages->nents)
246 					break;
247 
248 				sg = sg_next(sg);
249 				segment_len = sg_dma_len(sg) >> PAGE_SHIFT;
250 				m = 0;
251 			}
252 		}
253 
254 		kunmap_atomic(pt_vaddr);
255 
256 		first_pte = 0;
257 		act_pd++;
258 	}
259 }
260 
261 void i915_ppgtt_bind_object(struct i915_hw_ppgtt *ppgtt,
262 			    struct drm_i915_gem_object *obj,
263 			    enum i915_cache_level cache_level)
264 {
265 	i915_ppgtt_insert_sg_entries(ppgtt,
266 				     obj->pages,
267 				     obj->gtt_space->start >> PAGE_SHIFT,
268 				     cache_level);
269 }
270 
271 void i915_ppgtt_unbind_object(struct i915_hw_ppgtt *ppgtt,
272 			      struct drm_i915_gem_object *obj)
273 {
274 	i915_ppgtt_clear_range(ppgtt,
275 			       obj->gtt_space->start >> PAGE_SHIFT,
276 			       obj->base.size >> PAGE_SHIFT);
277 }
278 
279 void i915_gem_init_ppgtt(struct drm_device *dev)
280 {
281 	drm_i915_private_t *dev_priv = dev->dev_private;
282 	uint32_t pd_offset;
283 	struct intel_ring_buffer *ring;
284 	struct i915_hw_ppgtt *ppgtt = dev_priv->mm.aliasing_ppgtt;
285 	uint32_t __iomem *pd_addr;
286 	uint32_t pd_entry;
287 	int i;
288 
289 	if (!dev_priv->mm.aliasing_ppgtt)
290 		return;
291 
292 
293 	pd_addr = dev_priv->mm.gtt->gtt + ppgtt->pd_offset/sizeof(uint32_t);
294 	for (i = 0; i < ppgtt->num_pd_entries; i++) {
295 		dma_addr_t pt_addr;
296 
297 		if (dev_priv->mm.gtt->needs_dmar)
298 			pt_addr = ppgtt->pt_dma_addr[i];
299 		else
300 			pt_addr = page_to_phys(ppgtt->pt_pages[i]);
301 
302 		pd_entry = GEN6_PDE_ADDR_ENCODE(pt_addr);
303 		pd_entry |= GEN6_PDE_VALID;
304 
305 		writel(pd_entry, pd_addr + i);
306 	}
307 	readl(pd_addr);
308 
309 	pd_offset = ppgtt->pd_offset;
310 	pd_offset /= 64; /* in cachelines, */
311 	pd_offset <<= 16;
312 
313 	if (INTEL_INFO(dev)->gen == 6) {
314 		uint32_t ecochk, gab_ctl, ecobits;
315 
316 		ecobits = I915_READ(GAC_ECO_BITS);
317 		I915_WRITE(GAC_ECO_BITS, ecobits | ECOBITS_PPGTT_CACHE64B);
318 
319 		gab_ctl = I915_READ(GAB_CTL);
320 		I915_WRITE(GAB_CTL, gab_ctl | GAB_CTL_CONT_AFTER_PAGEFAULT);
321 
322 		ecochk = I915_READ(GAM_ECOCHK);
323 		I915_WRITE(GAM_ECOCHK, ecochk | ECOCHK_SNB_BIT |
324 				       ECOCHK_PPGTT_CACHE64B);
325 		I915_WRITE(GFX_MODE, _MASKED_BIT_ENABLE(GFX_PPGTT_ENABLE));
326 	} else if (INTEL_INFO(dev)->gen >= 7) {
327 		I915_WRITE(GAM_ECOCHK, ECOCHK_PPGTT_CACHE64B);
328 		/* GFX_MODE is per-ring on gen7+ */
329 	}
330 
331 	for_each_ring(ring, dev_priv, i) {
332 		if (INTEL_INFO(dev)->gen >= 7)
333 			I915_WRITE(RING_MODE_GEN7(ring),
334 				   _MASKED_BIT_ENABLE(GFX_PPGTT_ENABLE));
335 
336 		I915_WRITE(RING_PP_DIR_DCLV(ring), PP_DIR_DCLV_2G);
337 		I915_WRITE(RING_PP_DIR_BASE(ring), pd_offset);
338 	}
339 }
340 
341 static bool do_idling(struct drm_i915_private *dev_priv)
342 {
343 	bool ret = dev_priv->mm.interruptible;
344 
345 	if (unlikely(dev_priv->mm.gtt->do_idle_maps)) {
346 		dev_priv->mm.interruptible = false;
347 		if (i915_gpu_idle(dev_priv->dev)) {
348 			DRM_ERROR("Couldn't idle GPU\n");
349 			/* Wait a bit, in hopes it avoids the hang */
350 			udelay(10);
351 		}
352 	}
353 
354 	return ret;
355 }
356 
357 static void undo_idling(struct drm_i915_private *dev_priv, bool interruptible)
358 {
359 	if (unlikely(dev_priv->mm.gtt->do_idle_maps))
360 		dev_priv->mm.interruptible = interruptible;
361 }
362 
363 
364 static void i915_ggtt_clear_range(struct drm_device *dev,
365 				 unsigned first_entry,
366 				 unsigned num_entries)
367 {
368 	struct drm_i915_private *dev_priv = dev->dev_private;
369 	gtt_pte_t scratch_pte;
370 	gtt_pte_t __iomem *gtt_base = dev_priv->mm.gtt->gtt + first_entry;
371 	const int max_entries = dev_priv->mm.gtt->gtt_total_entries - first_entry;
372 	int i;
373 
374 	if (INTEL_INFO(dev)->gen < 6) {
375 		intel_gtt_clear_range(first_entry, num_entries);
376 		return;
377 	}
378 
379 	if (WARN(num_entries > max_entries,
380 		 "First entry = %d; Num entries = %d (max=%d)\n",
381 		 first_entry, num_entries, max_entries))
382 		num_entries = max_entries;
383 
384 	scratch_pte = pte_encode(dev, dev_priv->mm.gtt->scratch_page_dma, I915_CACHE_LLC);
385 	for (i = 0; i < num_entries; i++)
386 		iowrite32(scratch_pte, &gtt_base[i]);
387 	readl(gtt_base);
388 }
389 
390 void i915_gem_restore_gtt_mappings(struct drm_device *dev)
391 {
392 	struct drm_i915_private *dev_priv = dev->dev_private;
393 	struct drm_i915_gem_object *obj;
394 
395 	/* First fill our portion of the GTT with scratch pages */
396 	i915_ggtt_clear_range(dev, dev_priv->mm.gtt_start / PAGE_SIZE,
397 			      (dev_priv->mm.gtt_end - dev_priv->mm.gtt_start) / PAGE_SIZE);
398 
399 	list_for_each_entry(obj, &dev_priv->mm.bound_list, gtt_list) {
400 		i915_gem_clflush_object(obj);
401 		i915_gem_gtt_bind_object(obj, obj->cache_level);
402 	}
403 
404 	i915_gem_chipset_flush(dev);
405 }
406 
407 int i915_gem_gtt_prepare_object(struct drm_i915_gem_object *obj)
408 {
409 	if (obj->has_dma_mapping)
410 		return 0;
411 
412 	if (!dma_map_sg(&obj->base.dev->pdev->dev,
413 			obj->pages->sgl, obj->pages->nents,
414 			PCI_DMA_BIDIRECTIONAL))
415 		return -ENOSPC;
416 
417 	return 0;
418 }
419 
420 /*
421  * Binds an object into the global gtt with the specified cache level. The object
422  * will be accessible to the GPU via commands whose operands reference offsets
423  * within the global GTT as well as accessible by the GPU through the GMADR
424  * mapped BAR (dev_priv->mm.gtt->gtt).
425  */
426 static void gen6_ggtt_bind_object(struct drm_i915_gem_object *obj,
427 				  enum i915_cache_level level)
428 {
429 	struct drm_device *dev = obj->base.dev;
430 	struct drm_i915_private *dev_priv = dev->dev_private;
431 	struct sg_table *st = obj->pages;
432 	struct scatterlist *sg = st->sgl;
433 	const int first_entry = obj->gtt_space->start >> PAGE_SHIFT;
434 	const int max_entries = dev_priv->mm.gtt->gtt_total_entries - first_entry;
435 	gtt_pte_t __iomem *gtt_entries = dev_priv->mm.gtt->gtt + first_entry;
436 	int unused, i = 0;
437 	unsigned int len, m = 0;
438 	dma_addr_t addr;
439 
440 	for_each_sg(st->sgl, sg, st->nents, unused) {
441 		len = sg_dma_len(sg) >> PAGE_SHIFT;
442 		for (m = 0; m < len; m++) {
443 			addr = sg_dma_address(sg) + (m << PAGE_SHIFT);
444 			iowrite32(pte_encode(dev, addr, level), &gtt_entries[i]);
445 			i++;
446 		}
447 	}
448 
449 	BUG_ON(i > max_entries);
450 	BUG_ON(i != obj->base.size / PAGE_SIZE);
451 
452 	/* XXX: This serves as a posting read to make sure that the PTE has
453 	 * actually been updated. There is some concern that even though
454 	 * registers and PTEs are within the same BAR that they are potentially
455 	 * of NUMA access patterns. Therefore, even with the way we assume
456 	 * hardware should work, we must keep this posting read for paranoia.
457 	 */
458 	if (i != 0)
459 		WARN_ON(readl(&gtt_entries[i-1]) != pte_encode(dev, addr, level));
460 
461 	/* This next bit makes the above posting read even more important. We
462 	 * want to flush the TLBs only after we're certain all the PTE updates
463 	 * have finished.
464 	 */
465 	I915_WRITE(GFX_FLSH_CNTL_GEN6, GFX_FLSH_CNTL_EN);
466 	POSTING_READ(GFX_FLSH_CNTL_GEN6);
467 }
468 
469 void i915_gem_gtt_bind_object(struct drm_i915_gem_object *obj,
470 			      enum i915_cache_level cache_level)
471 {
472 	struct drm_device *dev = obj->base.dev;
473 	if (INTEL_INFO(dev)->gen < 6) {
474 		unsigned int flags = (cache_level == I915_CACHE_NONE) ?
475 			AGP_USER_MEMORY : AGP_USER_CACHED_MEMORY;
476 		intel_gtt_insert_sg_entries(obj->pages,
477 					    obj->gtt_space->start >> PAGE_SHIFT,
478 					    flags);
479 	} else {
480 		gen6_ggtt_bind_object(obj, cache_level);
481 	}
482 
483 	obj->has_global_gtt_mapping = 1;
484 }
485 
486 void i915_gem_gtt_unbind_object(struct drm_i915_gem_object *obj)
487 {
488 	i915_ggtt_clear_range(obj->base.dev,
489 			      obj->gtt_space->start >> PAGE_SHIFT,
490 			      obj->base.size >> PAGE_SHIFT);
491 
492 	obj->has_global_gtt_mapping = 0;
493 }
494 
495 void i915_gem_gtt_finish_object(struct drm_i915_gem_object *obj)
496 {
497 	struct drm_device *dev = obj->base.dev;
498 	struct drm_i915_private *dev_priv = dev->dev_private;
499 	bool interruptible;
500 
501 	interruptible = do_idling(dev_priv);
502 
503 	if (!obj->has_dma_mapping)
504 		dma_unmap_sg(&dev->pdev->dev,
505 			     obj->pages->sgl, obj->pages->nents,
506 			     PCI_DMA_BIDIRECTIONAL);
507 
508 	undo_idling(dev_priv, interruptible);
509 }
510 
511 static void i915_gtt_color_adjust(struct drm_mm_node *node,
512 				  unsigned long color,
513 				  unsigned long *start,
514 				  unsigned long *end)
515 {
516 	if (node->color != color)
517 		*start += 4096;
518 
519 	if (!list_empty(&node->node_list)) {
520 		node = list_entry(node->node_list.next,
521 				  struct drm_mm_node,
522 				  node_list);
523 		if (node->allocated && node->color != color)
524 			*end -= 4096;
525 	}
526 }
527 
528 void i915_gem_init_global_gtt(struct drm_device *dev,
529 			      unsigned long start,
530 			      unsigned long mappable_end,
531 			      unsigned long end)
532 {
533 	drm_i915_private_t *dev_priv = dev->dev_private;
534 
535 	/* Substract the guard page ... */
536 	drm_mm_init(&dev_priv->mm.gtt_space, start, end - start - PAGE_SIZE);
537 	if (!HAS_LLC(dev))
538 		dev_priv->mm.gtt_space.color_adjust = i915_gtt_color_adjust;
539 
540 	dev_priv->mm.gtt_start = start;
541 	dev_priv->mm.gtt_mappable_end = mappable_end;
542 	dev_priv->mm.gtt_end = end;
543 	dev_priv->mm.gtt_total = end - start;
544 	dev_priv->mm.mappable_gtt_total = min(end, mappable_end) - start;
545 
546 	/* ... but ensure that we clear the entire range. */
547 	i915_ggtt_clear_range(dev, start / PAGE_SIZE, (end-start) / PAGE_SIZE);
548 }
549 
550 static int setup_scratch_page(struct drm_device *dev)
551 {
552 	struct drm_i915_private *dev_priv = dev->dev_private;
553 	struct page *page;
554 	dma_addr_t dma_addr;
555 
556 	page = alloc_page(GFP_KERNEL | GFP_DMA32 | __GFP_ZERO);
557 	if (page == NULL)
558 		return -ENOMEM;
559 	get_page(page);
560 	set_pages_uc(page, 1);
561 
562 #ifdef CONFIG_INTEL_IOMMU
563 	dma_addr = pci_map_page(dev->pdev, page, 0, PAGE_SIZE,
564 				PCI_DMA_BIDIRECTIONAL);
565 	if (pci_dma_mapping_error(dev->pdev, dma_addr))
566 		return -EINVAL;
567 #else
568 	dma_addr = page_to_phys(page);
569 #endif
570 	dev_priv->mm.gtt->scratch_page = page;
571 	dev_priv->mm.gtt->scratch_page_dma = dma_addr;
572 
573 	return 0;
574 }
575 
576 static void teardown_scratch_page(struct drm_device *dev)
577 {
578 	struct drm_i915_private *dev_priv = dev->dev_private;
579 	set_pages_wb(dev_priv->mm.gtt->scratch_page, 1);
580 	pci_unmap_page(dev->pdev, dev_priv->mm.gtt->scratch_page_dma,
581 		       PAGE_SIZE, PCI_DMA_BIDIRECTIONAL);
582 	put_page(dev_priv->mm.gtt->scratch_page);
583 	__free_page(dev_priv->mm.gtt->scratch_page);
584 }
585 
586 static inline unsigned int gen6_get_total_gtt_size(u16 snb_gmch_ctl)
587 {
588 	snb_gmch_ctl >>= SNB_GMCH_GGMS_SHIFT;
589 	snb_gmch_ctl &= SNB_GMCH_GGMS_MASK;
590 	return snb_gmch_ctl << 20;
591 }
592 
593 static inline unsigned int gen6_get_stolen_size(u16 snb_gmch_ctl)
594 {
595 	snb_gmch_ctl >>= SNB_GMCH_GMS_SHIFT;
596 	snb_gmch_ctl &= SNB_GMCH_GMS_MASK;
597 	return snb_gmch_ctl << 25; /* 32 MB units */
598 }
599 
600 static inline unsigned int gen7_get_stolen_size(u16 snb_gmch_ctl)
601 {
602 	static const int stolen_decoder[] = {
603 		0, 0, 0, 0, 0, 32, 48, 64, 128, 256, 96, 160, 224, 352};
604 	snb_gmch_ctl >>= IVB_GMCH_GMS_SHIFT;
605 	snb_gmch_ctl &= IVB_GMCH_GMS_MASK;
606 	return stolen_decoder[snb_gmch_ctl] << 20;
607 }
608 
609 int i915_gem_gtt_init(struct drm_device *dev)
610 {
611 	struct drm_i915_private *dev_priv = dev->dev_private;
612 	phys_addr_t gtt_bus_addr;
613 	u16 snb_gmch_ctl;
614 	int ret;
615 
616 	/* On modern platforms we need not worry ourself with the legacy
617 	 * hostbridge query stuff. Skip it entirely
618 	 */
619 	if (INTEL_INFO(dev)->gen < 6) {
620 		ret = intel_gmch_probe(dev_priv->bridge_dev, dev->pdev, NULL);
621 		if (!ret) {
622 			DRM_ERROR("failed to set up gmch\n");
623 			return -EIO;
624 		}
625 
626 		dev_priv->mm.gtt = intel_gtt_get();
627 		if (!dev_priv->mm.gtt) {
628 			DRM_ERROR("Failed to initialize GTT\n");
629 			intel_gmch_remove();
630 			return -ENODEV;
631 		}
632 		return 0;
633 	}
634 
635 	dev_priv->mm.gtt = kzalloc(sizeof(*dev_priv->mm.gtt), GFP_KERNEL);
636 	if (!dev_priv->mm.gtt)
637 		return -ENOMEM;
638 
639 	if (!pci_set_dma_mask(dev->pdev, DMA_BIT_MASK(40)))
640 		pci_set_consistent_dma_mask(dev->pdev, DMA_BIT_MASK(40));
641 
642 #ifdef CONFIG_INTEL_IOMMU
643 	dev_priv->mm.gtt->needs_dmar = 1;
644 #endif
645 
646 	/* For GEN6+ the PTEs for the ggtt live at 2MB + BAR0 */
647 	gtt_bus_addr = pci_resource_start(dev->pdev, 0) + (2<<20);
648 	dev_priv->mm.gtt->gma_bus_addr = pci_resource_start(dev->pdev, 2);
649 
650 	/* i9xx_setup */
651 	pci_read_config_word(dev->pdev, SNB_GMCH_CTRL, &snb_gmch_ctl);
652 	dev_priv->mm.gtt->gtt_total_entries =
653 		gen6_get_total_gtt_size(snb_gmch_ctl) / sizeof(gtt_pte_t);
654 	if (INTEL_INFO(dev)->gen < 7)
655 		dev_priv->mm.gtt->stolen_size = gen6_get_stolen_size(snb_gmch_ctl);
656 	else
657 		dev_priv->mm.gtt->stolen_size = gen7_get_stolen_size(snb_gmch_ctl);
658 
659 	dev_priv->mm.gtt->gtt_mappable_entries = pci_resource_len(dev->pdev, 2) >> PAGE_SHIFT;
660 	/* 64/512MB is the current min/max we actually know of, but this is just a
661 	 * coarse sanity check.
662 	 */
663 	if ((dev_priv->mm.gtt->gtt_mappable_entries >> 8) < 64 ||
664 	    dev_priv->mm.gtt->gtt_mappable_entries > dev_priv->mm.gtt->gtt_total_entries) {
665 		DRM_ERROR("Unknown GMADR entries (%d)\n",
666 			  dev_priv->mm.gtt->gtt_mappable_entries);
667 		ret = -ENXIO;
668 		goto err_out;
669 	}
670 
671 	ret = setup_scratch_page(dev);
672 	if (ret) {
673 		DRM_ERROR("Scratch setup failed\n");
674 		goto err_out;
675 	}
676 
677 	dev_priv->mm.gtt->gtt = ioremap_wc(gtt_bus_addr,
678 					   dev_priv->mm.gtt->gtt_total_entries * sizeof(gtt_pte_t));
679 	if (!dev_priv->mm.gtt->gtt) {
680 		DRM_ERROR("Failed to map the gtt page table\n");
681 		teardown_scratch_page(dev);
682 		ret = -ENOMEM;
683 		goto err_out;
684 	}
685 
686 	/* GMADR is the PCI aperture used by SW to access tiled GFX surfaces in a linear fashion. */
687 	DRM_INFO("Memory usable by graphics device = %dM\n", dev_priv->mm.gtt->gtt_total_entries >> 8);
688 	DRM_DEBUG_DRIVER("GMADR size = %dM\n", dev_priv->mm.gtt->gtt_mappable_entries >> 8);
689 	DRM_DEBUG_DRIVER("GTT stolen size = %dM\n", dev_priv->mm.gtt->stolen_size >> 20);
690 
691 	return 0;
692 
693 err_out:
694 	kfree(dev_priv->mm.gtt);
695 	if (INTEL_INFO(dev)->gen < 6)
696 		intel_gmch_remove();
697 	return ret;
698 }
699 
700 void i915_gem_gtt_fini(struct drm_device *dev)
701 {
702 	struct drm_i915_private *dev_priv = dev->dev_private;
703 	iounmap(dev_priv->mm.gtt->gtt);
704 	teardown_scratch_page(dev);
705 	if (INTEL_INFO(dev)->gen < 6)
706 		intel_gmch_remove();
707 	kfree(dev_priv->mm.gtt);
708 }
709