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 */
53static 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 */
84struct ppc_vm_region {
85	struct list_head	vm_list;
86	unsigned long		vm_start;
87	unsigned long		vm_end;
88};
89
90static 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
96static struct ppc_vm_region *
97ppc_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
137static 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 */
154void *
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_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}
252EXPORT_SYMBOL(__dma_alloc_coherent);
253
254/*
255 * free a page as defined by the above mapping.
256 */
257void __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}
312EXPORT_SYMBOL(__dma_free_coherent);
313
314/*
315 * make an area consistent.
316 */
317void __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 & (L1_CACHE_BYTES - 1)) || (size & (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}
343EXPORT_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 */
355static 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 */
390void __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}
400EXPORT_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 */
406unsigned 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