1 /*
2  *  PowerPC version derived from arch/arm/mm/consistent.c
3  *    Copyright (C) 2001 Dan Malek (dmalek@jlc.net)
4  *
5  *  Copyright (C) 2000 Russell King
6  *
7  * Consistent memory allocators.  Used for DMA devices that want to
8  * share uncached memory with the processor core.  The function return
9  * is the virtual address and 'dma_handle' is the physical address.
10  * Mostly stolen from the ARM port, with some changes for PowerPC.
11  *						-- Dan
12  *
13  * Reorganized to get rid of the arch-specific consistent_* functions
14  * and provide non-coherent implementations for the DMA API. -Matt
15  *
16  * Added in_interrupt() safe dma_alloc_coherent()/dma_free_coherent()
17  * implementation. This is pulled straight from ARM and barely
18  * modified. -Matt
19  *
20  * This program is free software; you can redistribute it and/or modify
21  * it under the terms of the GNU General Public License version 2 as
22  * published by the Free Software Foundation.
23  */
24 
25 #include <linux/sched.h>
26 #include <linux/slab.h>
27 #include <linux/kernel.h>
28 #include <linux/errno.h>
29 #include <linux/string.h>
30 #include <linux/types.h>
31 #include <linux/highmem.h>
32 #include <linux/dma-mapping.h>
33 #include <linux/export.h>
34 
35 #include <asm/tlbflush.h>
36 
37 #include "mmu_decl.h"
38 
39 /*
40  * This address range defaults to a value that is safe for all
41  * platforms which currently set CONFIG_NOT_COHERENT_CACHE. It
42  * can be further configured for specific applications under
43  * the "Advanced Setup" menu. -Matt
44  */
45 #define CONSISTENT_BASE		(IOREMAP_TOP)
46 #define CONSISTENT_END 		(CONSISTENT_BASE + CONFIG_CONSISTENT_SIZE)
47 #define CONSISTENT_OFFSET(x)	(((unsigned long)(x) - CONSISTENT_BASE) >> PAGE_SHIFT)
48 
49 /*
50  * This is the page table (2MB) covering uncached, DMA consistent allocations
51  */
52 static DEFINE_SPINLOCK(consistent_lock);
53 
54 /*
55  * VM region handling support.
56  *
57  * This should become something generic, handling VM region allocations for
58  * vmalloc and similar (ioremap, module space, etc).
59  *
60  * I envisage vmalloc()'s supporting vm_struct becoming:
61  *
62  *  struct vm_struct {
63  *    struct vm_region	region;
64  *    unsigned long	flags;
65  *    struct page	**pages;
66  *    unsigned int	nr_pages;
67  *    unsigned long	phys_addr;
68  *  };
69  *
70  * get_vm_area() would then call vm_region_alloc with an appropriate
71  * struct vm_region head (eg):
72  *
73  *  struct vm_region vmalloc_head = {
74  *	.vm_list	= LIST_HEAD_INIT(vmalloc_head.vm_list),
75  *	.vm_start	= VMALLOC_START,
76  *	.vm_end		= VMALLOC_END,
77  *  };
78  *
79  * However, vmalloc_head.vm_start is variable (typically, it is dependent on
80  * the amount of RAM found at boot time.)  I would imagine that get_vm_area()
81  * would have to initialise this each time prior to calling vm_region_alloc().
82  */
83 struct ppc_vm_region {
84 	struct list_head	vm_list;
85 	unsigned long		vm_start;
86 	unsigned long		vm_end;
87 };
88 
89 static struct ppc_vm_region consistent_head = {
90 	.vm_list	= LIST_HEAD_INIT(consistent_head.vm_list),
91 	.vm_start	= CONSISTENT_BASE,
92 	.vm_end		= CONSISTENT_END,
93 };
94 
95 static struct ppc_vm_region *
96 ppc_vm_region_alloc(struct ppc_vm_region *head, size_t size, gfp_t gfp)
97 {
98 	unsigned long addr = head->vm_start, end = head->vm_end - size;
99 	unsigned long flags;
100 	struct ppc_vm_region *c, *new;
101 
102 	new = kmalloc(sizeof(struct ppc_vm_region), gfp);
103 	if (!new)
104 		goto out;
105 
106 	spin_lock_irqsave(&consistent_lock, flags);
107 
108 	list_for_each_entry(c, &head->vm_list, vm_list) {
109 		if ((addr + size) < addr)
110 			goto nospc;
111 		if ((addr + size) <= c->vm_start)
112 			goto found;
113 		addr = c->vm_end;
114 		if (addr > end)
115 			goto nospc;
116 	}
117 
118  found:
119 	/*
120 	 * Insert this entry _before_ the one we found.
121 	 */
122 	list_add_tail(&new->vm_list, &c->vm_list);
123 	new->vm_start = addr;
124 	new->vm_end = addr + size;
125 
126 	spin_unlock_irqrestore(&consistent_lock, flags);
127 	return new;
128 
129  nospc:
130 	spin_unlock_irqrestore(&consistent_lock, flags);
131 	kfree(new);
132  out:
133 	return NULL;
134 }
135 
136 static struct ppc_vm_region *ppc_vm_region_find(struct ppc_vm_region *head, unsigned long addr)
137 {
138 	struct ppc_vm_region *c;
139 
140 	list_for_each_entry(c, &head->vm_list, vm_list) {
141 		if (c->vm_start == addr)
142 			goto out;
143 	}
144 	c = NULL;
145  out:
146 	return c;
147 }
148 
149 /*
150  * Allocate DMA-coherent memory space and return both the kernel remapped
151  * virtual and bus address for that space.
152  */
153 void *
154 __dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp)
155 {
156 	struct page *page;
157 	struct ppc_vm_region *c;
158 	unsigned long order;
159 	u64 mask = ISA_DMA_THRESHOLD, limit;
160 
161 	if (dev) {
162 		mask = dev->coherent_dma_mask;
163 
164 		/*
165 		 * Sanity check the DMA mask - it must be non-zero, and
166 		 * must be able to be satisfied by a DMA allocation.
167 		 */
168 		if (mask == 0) {
169 			dev_warn(dev, "coherent DMA mask is unset\n");
170 			goto no_page;
171 		}
172 
173 		if ((~mask) & ISA_DMA_THRESHOLD) {
174 			dev_warn(dev, "coherent DMA mask %#llx is smaller "
175 				 "than system GFP_DMA mask %#llx\n",
176 				 mask, (unsigned long long)ISA_DMA_THRESHOLD);
177 			goto no_page;
178 		}
179 	}
180 
181 
182 	size = PAGE_ALIGN(size);
183 	limit = (mask + 1) & ~mask;
184 	if ((limit && size >= limit) ||
185 	    size >= (CONSISTENT_END - CONSISTENT_BASE)) {
186 		printk(KERN_WARNING "coherent allocation too big (requested %#x mask %#Lx)\n",
187 		       size, mask);
188 		return NULL;
189 	}
190 
191 	order = get_order(size);
192 
193 	/* Might be useful if we ever have a real legacy DMA zone... */
194 	if (mask != 0xffffffff)
195 		gfp |= GFP_DMA;
196 
197 	page = alloc_pages(gfp, order);
198 	if (!page)
199 		goto no_page;
200 
201 	/*
202 	 * Invalidate any data that might be lurking in the
203 	 * kernel direct-mapped region for device DMA.
204 	 */
205 	{
206 		unsigned long kaddr = (unsigned long)page_address(page);
207 		memset(page_address(page), 0, size);
208 		flush_dcache_range(kaddr, kaddr + size);
209 	}
210 
211 	/*
212 	 * Allocate a virtual address in the consistent mapping region.
213 	 */
214 	c = ppc_vm_region_alloc(&consistent_head, size,
215 			    gfp & ~(__GFP_DMA | __GFP_HIGHMEM));
216 	if (c) {
217 		unsigned long vaddr = c->vm_start;
218 		struct page *end = page + (1 << order);
219 
220 		split_page(page, order);
221 
222 		/*
223 		 * Set the "dma handle"
224 		 */
225 		*handle = page_to_phys(page);
226 
227 		do {
228 			SetPageReserved(page);
229 			map_page(vaddr, page_to_phys(page),
230 				 pgprot_noncached(PAGE_KERNEL));
231 			page++;
232 			vaddr += PAGE_SIZE;
233 		} while (size -= PAGE_SIZE);
234 
235 		/*
236 		 * Free the otherwise unused pages.
237 		 */
238 		while (page < end) {
239 			__free_page(page);
240 			page++;
241 		}
242 
243 		return (void *)c->vm_start;
244 	}
245 
246 	if (page)
247 		__free_pages(page, order);
248  no_page:
249 	return NULL;
250 }
251 EXPORT_SYMBOL(__dma_alloc_coherent);
252 
253 /*
254  * free a page as defined by the above mapping.
255  */
256 void __dma_free_coherent(size_t size, void *vaddr)
257 {
258 	struct ppc_vm_region *c;
259 	unsigned long flags, addr;
260 
261 	size = PAGE_ALIGN(size);
262 
263 	spin_lock_irqsave(&consistent_lock, flags);
264 
265 	c = ppc_vm_region_find(&consistent_head, (unsigned long)vaddr);
266 	if (!c)
267 		goto no_area;
268 
269 	if ((c->vm_end - c->vm_start) != size) {
270 		printk(KERN_ERR "%s: freeing wrong coherent size (%ld != %d)\n",
271 		       __func__, c->vm_end - c->vm_start, size);
272 		dump_stack();
273 		size = c->vm_end - c->vm_start;
274 	}
275 
276 	addr = c->vm_start;
277 	do {
278 		pte_t *ptep;
279 		unsigned long pfn;
280 
281 		ptep = pte_offset_kernel(pmd_offset(pud_offset(pgd_offset_k(addr),
282 							       addr),
283 						    addr),
284 					 addr);
285 		if (!pte_none(*ptep) && pte_present(*ptep)) {
286 			pfn = pte_pfn(*ptep);
287 			pte_clear(&init_mm, addr, ptep);
288 			if (pfn_valid(pfn)) {
289 				struct page *page = pfn_to_page(pfn);
290 				__free_reserved_page(page);
291 			}
292 		}
293 		addr += PAGE_SIZE;
294 	} while (size -= PAGE_SIZE);
295 
296 	flush_tlb_kernel_range(c->vm_start, c->vm_end);
297 
298 	list_del(&c->vm_list);
299 
300 	spin_unlock_irqrestore(&consistent_lock, flags);
301 
302 	kfree(c);
303 	return;
304 
305  no_area:
306 	spin_unlock_irqrestore(&consistent_lock, flags);
307 	printk(KERN_ERR "%s: trying to free invalid coherent area: %p\n",
308 	       __func__, vaddr);
309 	dump_stack();
310 }
311 EXPORT_SYMBOL(__dma_free_coherent);
312 
313 /*
314  * make an area consistent.
315  */
316 void __dma_sync(void *vaddr, size_t size, int direction)
317 {
318 	unsigned long start = (unsigned long)vaddr;
319 	unsigned long end   = start + size;
320 
321 	switch (direction) {
322 	case DMA_NONE:
323 		BUG();
324 	case DMA_FROM_DEVICE:
325 		/*
326 		 * invalidate only when cache-line aligned otherwise there is
327 		 * the potential for discarding uncommitted data from the cache
328 		 */
329 		if ((start & (L1_CACHE_BYTES - 1)) || (size & (L1_CACHE_BYTES - 1)))
330 			flush_dcache_range(start, end);
331 		else
332 			invalidate_dcache_range(start, end);
333 		break;
334 	case DMA_TO_DEVICE:		/* writeback only */
335 		clean_dcache_range(start, end);
336 		break;
337 	case DMA_BIDIRECTIONAL:	/* writeback and invalidate */
338 		flush_dcache_range(start, end);
339 		break;
340 	}
341 }
342 EXPORT_SYMBOL(__dma_sync);
343 
344 #ifdef CONFIG_HIGHMEM
345 /*
346  * __dma_sync_page() implementation for systems using highmem.
347  * In this case, each page of a buffer must be kmapped/kunmapped
348  * in order to have a virtual address for __dma_sync(). This must
349  * not sleep so kmap_atomic()/kunmap_atomic() are used.
350  *
351  * Note: yes, it is possible and correct to have a buffer extend
352  * beyond the first page.
353  */
354 static inline void __dma_sync_page_highmem(struct page *page,
355 		unsigned long offset, size_t size, int direction)
356 {
357 	size_t seg_size = min((size_t)(PAGE_SIZE - offset), size);
358 	size_t cur_size = seg_size;
359 	unsigned long flags, start, seg_offset = offset;
360 	int nr_segs = 1 + ((size - seg_size) + PAGE_SIZE - 1)/PAGE_SIZE;
361 	int seg_nr = 0;
362 
363 	local_irq_save(flags);
364 
365 	do {
366 		start = (unsigned long)kmap_atomic(page + seg_nr) + seg_offset;
367 
368 		/* Sync this buffer segment */
369 		__dma_sync((void *)start, seg_size, direction);
370 		kunmap_atomic((void *)start);
371 		seg_nr++;
372 
373 		/* Calculate next buffer segment size */
374 		seg_size = min((size_t)PAGE_SIZE, size - cur_size);
375 
376 		/* Add the segment size to our running total */
377 		cur_size += seg_size;
378 		seg_offset = 0;
379 	} while (seg_nr < nr_segs);
380 
381 	local_irq_restore(flags);
382 }
383 #endif /* CONFIG_HIGHMEM */
384 
385 /*
386  * __dma_sync_page makes memory consistent. identical to __dma_sync, but
387  * takes a struct page instead of a virtual address
388  */
389 void __dma_sync_page(struct page *page, unsigned long offset,
390 	size_t size, int direction)
391 {
392 #ifdef CONFIG_HIGHMEM
393 	__dma_sync_page_highmem(page, offset, size, direction);
394 #else
395 	unsigned long start = (unsigned long)page_address(page) + offset;
396 	__dma_sync((void *)start, size, direction);
397 #endif
398 }
399 EXPORT_SYMBOL(__dma_sync_page);
400 
401 /*
402  * Return the PFN for a given cpu virtual address returned by
403  * __dma_alloc_coherent. This is used by dma_mmap_coherent()
404  */
405 unsigned long __dma_get_coherent_pfn(unsigned long cpu_addr)
406 {
407 	/* This should always be populated, so we don't test every
408 	 * level. If that fails, we'll have a nice crash which
409 	 * will be as good as a BUG_ON()
410 	 */
411 	pgd_t *pgd = pgd_offset_k(cpu_addr);
412 	pud_t *pud = pud_offset(pgd, cpu_addr);
413 	pmd_t *pmd = pmd_offset(pud, cpu_addr);
414 	pte_t *ptep = pte_offset_kernel(pmd, cpu_addr);
415 
416 	if (pte_none(*ptep) || !pte_present(*ptep))
417 		return 0;
418 	return pte_pfn(*ptep);
419 }
420