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 #include <asm/dma.h>
37 
38 #include "mmu_decl.h"
39 
40 /*
41  * This address range defaults to a value that is safe for all
42  * platforms which currently set CONFIG_NOT_COHERENT_CACHE. It
43  * can be further configured for specific applications under
44  * the "Advanced Setup" menu. -Matt
45  */
46 #define CONSISTENT_BASE		(IOREMAP_TOP)
47 #define CONSISTENT_END 		(CONSISTENT_BASE + CONFIG_CONSISTENT_SIZE)
48 #define CONSISTENT_OFFSET(x)	(((unsigned long)(x) - CONSISTENT_BASE) >> PAGE_SHIFT)
49 
50 /*
51  * This is the page table (2MB) covering uncached, DMA consistent allocations
52  */
53 static DEFINE_SPINLOCK(consistent_lock);
54 
55 /*
56  * VM region handling support.
57  *
58  * This should become something generic, handling VM region allocations for
59  * vmalloc and similar (ioremap, module space, etc).
60  *
61  * I envisage vmalloc()'s supporting vm_struct becoming:
62  *
63  *  struct vm_struct {
64  *    struct vm_region	region;
65  *    unsigned long	flags;
66  *    struct page	**pages;
67  *    unsigned int	nr_pages;
68  *    unsigned long	phys_addr;
69  *  };
70  *
71  * get_vm_area() would then call vm_region_alloc with an appropriate
72  * struct vm_region head (eg):
73  *
74  *  struct vm_region vmalloc_head = {
75  *	.vm_list	= LIST_HEAD_INIT(vmalloc_head.vm_list),
76  *	.vm_start	= VMALLOC_START,
77  *	.vm_end		= VMALLOC_END,
78  *  };
79  *
80  * However, vmalloc_head.vm_start is variable (typically, it is dependent on
81  * the amount of RAM found at boot time.)  I would imagine that get_vm_area()
82  * would have to initialise this each time prior to calling vm_region_alloc().
83  */
84 struct ppc_vm_region {
85 	struct list_head	vm_list;
86 	unsigned long		vm_start;
87 	unsigned long		vm_end;
88 };
89 
90 static struct ppc_vm_region consistent_head = {
91 	.vm_list	= LIST_HEAD_INIT(consistent_head.vm_list),
92 	.vm_start	= CONSISTENT_BASE,
93 	.vm_end		= CONSISTENT_END,
94 };
95 
96 static struct ppc_vm_region *
97 ppc_vm_region_alloc(struct ppc_vm_region *head, size_t size, gfp_t gfp)
98 {
99 	unsigned long addr = head->vm_start, end = head->vm_end - size;
100 	unsigned long flags;
101 	struct ppc_vm_region *c, *new;
102 
103 	new = kmalloc(sizeof(struct ppc_vm_region), gfp);
104 	if (!new)
105 		goto out;
106 
107 	spin_lock_irqsave(&consistent_lock, flags);
108 
109 	list_for_each_entry(c, &head->vm_list, vm_list) {
110 		if ((addr + size) < addr)
111 			goto nospc;
112 		if ((addr + size) <= c->vm_start)
113 			goto found;
114 		addr = c->vm_end;
115 		if (addr > end)
116 			goto nospc;
117 	}
118 
119  found:
120 	/*
121 	 * Insert this entry _before_ the one we found.
122 	 */
123 	list_add_tail(&new->vm_list, &c->vm_list);
124 	new->vm_start = addr;
125 	new->vm_end = addr + size;
126 
127 	spin_unlock_irqrestore(&consistent_lock, flags);
128 	return new;
129 
130  nospc:
131 	spin_unlock_irqrestore(&consistent_lock, flags);
132 	kfree(new);
133  out:
134 	return NULL;
135 }
136 
137 static struct ppc_vm_region *ppc_vm_region_find(struct ppc_vm_region *head, unsigned long addr)
138 {
139 	struct ppc_vm_region *c;
140 
141 	list_for_each_entry(c, &head->vm_list, vm_list) {
142 		if (c->vm_start == addr)
143 			goto out;
144 	}
145 	c = NULL;
146  out:
147 	return c;
148 }
149 
150 /*
151  * Allocate DMA-coherent memory space and return both the kernel remapped
152  * virtual and bus address for that space.
153  */
154 void *
155 __dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp)
156 {
157 	struct page *page;
158 	struct ppc_vm_region *c;
159 	unsigned long order;
160 	u64 mask = ISA_DMA_THRESHOLD, limit;
161 
162 	if (dev) {
163 		mask = dev->coherent_dma_mask;
164 
165 		/*
166 		 * Sanity check the DMA mask - it must be non-zero, and
167 		 * must be able to be satisfied by a DMA allocation.
168 		 */
169 		if (mask == 0) {
170 			dev_warn(dev, "coherent DMA mask is unset\n");
171 			goto no_page;
172 		}
173 
174 		if ((~mask) & ISA_DMA_THRESHOLD) {
175 			dev_warn(dev, "coherent DMA mask %#llx is smaller "
176 				 "than system GFP_DMA mask %#llx\n",
177 				 mask, (unsigned long long)ISA_DMA_THRESHOLD);
178 			goto no_page;
179 		}
180 	}
181 
182 
183 	size = PAGE_ALIGN(size);
184 	limit = (mask + 1) & ~mask;
185 	if ((limit && size >= limit) ||
186 	    size >= (CONSISTENT_END - CONSISTENT_BASE)) {
187 		printk(KERN_WARNING "coherent allocation too big (requested %#x mask %#Lx)\n",
188 		       size, mask);
189 		return NULL;
190 	}
191 
192 	order = get_order(size);
193 
194 	/* Might be useful if we ever have a real legacy DMA zone... */
195 	if (mask != 0xffffffff)
196 		gfp |= GFP_DMA;
197 
198 	page = alloc_pages(gfp, order);
199 	if (!page)
200 		goto no_page;
201 
202 	/*
203 	 * Invalidate any data that might be lurking in the
204 	 * kernel direct-mapped region for device DMA.
205 	 */
206 	{
207 		unsigned long kaddr = (unsigned long)page_address(page);
208 		memset(page_address(page), 0, size);
209 		flush_dcache_range(kaddr, kaddr + size);
210 	}
211 
212 	/*
213 	 * Allocate a virtual address in the consistent mapping region.
214 	 */
215 	c = ppc_vm_region_alloc(&consistent_head, size,
216 			    gfp & ~(__GFP_DMA | __GFP_HIGHMEM));
217 	if (c) {
218 		unsigned long vaddr = c->vm_start;
219 		struct page *end = page + (1 << order);
220 
221 		split_page(page, order);
222 
223 		/*
224 		 * Set the "dma handle"
225 		 */
226 		*handle = page_to_phys(page);
227 
228 		do {
229 			SetPageReserved(page);
230 			map_kernel_page(vaddr, page_to_phys(page),
231 				 pgprot_val(pgprot_noncached(PAGE_KERNEL)));
232 			page++;
233 			vaddr += PAGE_SIZE;
234 		} while (size -= PAGE_SIZE);
235 
236 		/*
237 		 * Free the otherwise unused pages.
238 		 */
239 		while (page < end) {
240 			__free_page(page);
241 			page++;
242 		}
243 
244 		return (void *)c->vm_start;
245 	}
246 
247 	if (page)
248 		__free_pages(page, order);
249  no_page:
250 	return NULL;
251 }
252 EXPORT_SYMBOL(__dma_alloc_coherent);
253 
254 /*
255  * free a page as defined by the above mapping.
256  */
257 void __dma_free_coherent(size_t size, void *vaddr)
258 {
259 	struct ppc_vm_region *c;
260 	unsigned long flags, addr;
261 
262 	size = PAGE_ALIGN(size);
263 
264 	spin_lock_irqsave(&consistent_lock, flags);
265 
266 	c = ppc_vm_region_find(&consistent_head, (unsigned long)vaddr);
267 	if (!c)
268 		goto no_area;
269 
270 	if ((c->vm_end - c->vm_start) != size) {
271 		printk(KERN_ERR "%s: freeing wrong coherent size (%ld != %d)\n",
272 		       __func__, c->vm_end - c->vm_start, size);
273 		dump_stack();
274 		size = c->vm_end - c->vm_start;
275 	}
276 
277 	addr = c->vm_start;
278 	do {
279 		pte_t *ptep;
280 		unsigned long pfn;
281 
282 		ptep = pte_offset_kernel(pmd_offset(pud_offset(pgd_offset_k(addr),
283 							       addr),
284 						    addr),
285 					 addr);
286 		if (!pte_none(*ptep) && pte_present(*ptep)) {
287 			pfn = pte_pfn(*ptep);
288 			pte_clear(&init_mm, addr, ptep);
289 			if (pfn_valid(pfn)) {
290 				struct page *page = pfn_to_page(pfn);
291 				__free_reserved_page(page);
292 			}
293 		}
294 		addr += PAGE_SIZE;
295 	} while (size -= PAGE_SIZE);
296 
297 	flush_tlb_kernel_range(c->vm_start, c->vm_end);
298 
299 	list_del(&c->vm_list);
300 
301 	spin_unlock_irqrestore(&consistent_lock, flags);
302 
303 	kfree(c);
304 	return;
305 
306  no_area:
307 	spin_unlock_irqrestore(&consistent_lock, flags);
308 	printk(KERN_ERR "%s: trying to free invalid coherent area: %p\n",
309 	       __func__, vaddr);
310 	dump_stack();
311 }
312 EXPORT_SYMBOL(__dma_free_coherent);
313 
314 /*
315  * make an area consistent.
316  */
317 void __dma_sync(void *vaddr, size_t size, int direction)
318 {
319 	unsigned long start = (unsigned long)vaddr;
320 	unsigned long end   = start + size;
321 
322 	switch (direction) {
323 	case DMA_NONE:
324 		BUG();
325 	case DMA_FROM_DEVICE:
326 		/*
327 		 * invalidate only when cache-line aligned otherwise there is
328 		 * the potential for discarding uncommitted data from the cache
329 		 */
330 		if ((start | end) & (L1_CACHE_BYTES - 1))
331 			flush_dcache_range(start, end);
332 		else
333 			invalidate_dcache_range(start, end);
334 		break;
335 	case DMA_TO_DEVICE:		/* writeback only */
336 		clean_dcache_range(start, end);
337 		break;
338 	case DMA_BIDIRECTIONAL:	/* writeback and invalidate */
339 		flush_dcache_range(start, end);
340 		break;
341 	}
342 }
343 EXPORT_SYMBOL(__dma_sync);
344 
345 #ifdef CONFIG_HIGHMEM
346 /*
347  * __dma_sync_page() implementation for systems using highmem.
348  * In this case, each page of a buffer must be kmapped/kunmapped
349  * in order to have a virtual address for __dma_sync(). This must
350  * not sleep so kmap_atomic()/kunmap_atomic() are used.
351  *
352  * Note: yes, it is possible and correct to have a buffer extend
353  * beyond the first page.
354  */
355 static inline void __dma_sync_page_highmem(struct page *page,
356 		unsigned long offset, size_t size, int direction)
357 {
358 	size_t seg_size = min((size_t)(PAGE_SIZE - offset), size);
359 	size_t cur_size = seg_size;
360 	unsigned long flags, start, seg_offset = offset;
361 	int nr_segs = 1 + ((size - seg_size) + PAGE_SIZE - 1)/PAGE_SIZE;
362 	int seg_nr = 0;
363 
364 	local_irq_save(flags);
365 
366 	do {
367 		start = (unsigned long)kmap_atomic(page + seg_nr) + seg_offset;
368 
369 		/* Sync this buffer segment */
370 		__dma_sync((void *)start, seg_size, direction);
371 		kunmap_atomic((void *)start);
372 		seg_nr++;
373 
374 		/* Calculate next buffer segment size */
375 		seg_size = min((size_t)PAGE_SIZE, size - cur_size);
376 
377 		/* Add the segment size to our running total */
378 		cur_size += seg_size;
379 		seg_offset = 0;
380 	} while (seg_nr < nr_segs);
381 
382 	local_irq_restore(flags);
383 }
384 #endif /* CONFIG_HIGHMEM */
385 
386 /*
387  * __dma_sync_page makes memory consistent. identical to __dma_sync, but
388  * takes a struct page instead of a virtual address
389  */
390 void __dma_sync_page(struct page *page, unsigned long offset,
391 	size_t size, int direction)
392 {
393 #ifdef CONFIG_HIGHMEM
394 	__dma_sync_page_highmem(page, offset, size, direction);
395 #else
396 	unsigned long start = (unsigned long)page_address(page) + offset;
397 	__dma_sync((void *)start, size, direction);
398 #endif
399 }
400 EXPORT_SYMBOL(__dma_sync_page);
401 
402 /*
403  * Return the PFN for a given cpu virtual address returned by
404  * __dma_alloc_coherent. This is used by dma_mmap_coherent()
405  */
406 unsigned long __dma_get_coherent_pfn(unsigned long cpu_addr)
407 {
408 	/* This should always be populated, so we don't test every
409 	 * level. If that fails, we'll have a nice crash which
410 	 * will be as good as a BUG_ON()
411 	 */
412 	pgd_t *pgd = pgd_offset_k(cpu_addr);
413 	pud_t *pud = pud_offset(pgd, cpu_addr);
414 	pmd_t *pmd = pmd_offset(pud, cpu_addr);
415 	pte_t *ptep = pte_offset_kernel(pmd, cpu_addr);
416 
417 	if (pte_none(*ptep) || !pte_present(*ptep))
418 		return 0;
419 	return pte_pfn(*ptep);
420 }
421