Root/drivers/base/dma-contiguous.c

1/*
2 * Contiguous Memory Allocator for DMA mapping framework
3 * Copyright (c) 2010-2011 by Samsung Electronics.
4 * Written by:
5 * Marek Szyprowski <m.szyprowski@samsung.com>
6 * Michal Nazarewicz <mina86@mina86.com>
7 *
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License as
10 * published by the Free Software Foundation; either version 2 of the
11 * License or (at your optional) any later version of the license.
12 */
13
14#define pr_fmt(fmt) "cma: " fmt
15
16#ifdef CONFIG_CMA_DEBUG
17#ifndef DEBUG
18# define DEBUG
19#endif
20#endif
21
22#include <asm/page.h>
23#include <asm/dma-contiguous.h>
24
25#include <linux/memblock.h>
26#include <linux/err.h>
27#include <linux/mm.h>
28#include <linux/mutex.h>
29#include <linux/page-isolation.h>
30#include <linux/sizes.h>
31#include <linux/slab.h>
32#include <linux/swap.h>
33#include <linux/mm_types.h>
34#include <linux/dma-contiguous.h>
35
36struct cma {
37    unsigned long base_pfn;
38    unsigned long count;
39    unsigned long *bitmap;
40};
41
42struct cma *dma_contiguous_default_area;
43
44#ifdef CONFIG_CMA_SIZE_MBYTES
45#define CMA_SIZE_MBYTES CONFIG_CMA_SIZE_MBYTES
46#else
47#define CMA_SIZE_MBYTES 0
48#endif
49
50/*
51 * Default global CMA area size can be defined in kernel's .config.
52 * This is usefull mainly for distro maintainers to create a kernel
53 * that works correctly for most supported systems.
54 * The size can be set in bytes or as a percentage of the total memory
55 * in the system.
56 *
57 * Users, who want to set the size of global CMA area for their system
58 * should use cma= kernel parameter.
59 */
60static const phys_addr_t size_bytes = CMA_SIZE_MBYTES * SZ_1M;
61static phys_addr_t size_cmdline = -1;
62
63static int __init early_cma(char *p)
64{
65    pr_debug("%s(%s)\n", __func__, p);
66    size_cmdline = memparse(p, &p);
67    return 0;
68}
69early_param("cma", early_cma);
70
71#ifdef CONFIG_CMA_SIZE_PERCENTAGE
72
73static phys_addr_t __init __maybe_unused cma_early_percent_memory(void)
74{
75    struct memblock_region *reg;
76    unsigned long total_pages = 0;
77
78    /*
79     * We cannot use memblock_phys_mem_size() here, because
80     * memblock_analyze() has not been called yet.
81     */
82    for_each_memblock(memory, reg)
83        total_pages += memblock_region_memory_end_pfn(reg) -
84                   memblock_region_memory_base_pfn(reg);
85
86    return (total_pages * CONFIG_CMA_SIZE_PERCENTAGE / 100) << PAGE_SHIFT;
87}
88
89#else
90
91static inline __maybe_unused phys_addr_t cma_early_percent_memory(void)
92{
93    return 0;
94}
95
96#endif
97
98/**
99 * dma_contiguous_reserve() - reserve area for contiguous memory handling
100 * @limit: End address of the reserved memory (optional, 0 for any).
101 *
102 * This function reserves memory from early allocator. It should be
103 * called by arch specific code once the early allocator (memblock or bootmem)
104 * has been activated and all other subsystems have already allocated/reserved
105 * memory.
106 */
107void __init dma_contiguous_reserve(phys_addr_t limit)
108{
109    phys_addr_t selected_size = 0;
110
111    pr_debug("%s(limit %08lx)\n", __func__, (unsigned long)limit);
112
113    if (size_cmdline != -1) {
114        selected_size = size_cmdline;
115    } else {
116#ifdef CONFIG_CMA_SIZE_SEL_MBYTES
117        selected_size = size_bytes;
118#elif defined(CONFIG_CMA_SIZE_SEL_PERCENTAGE)
119        selected_size = cma_early_percent_memory();
120#elif defined(CONFIG_CMA_SIZE_SEL_MIN)
121        selected_size = min(size_bytes, cma_early_percent_memory());
122#elif defined(CONFIG_CMA_SIZE_SEL_MAX)
123        selected_size = max(size_bytes, cma_early_percent_memory());
124#endif
125    }
126
127    if (selected_size) {
128        pr_debug("%s: reserving %ld MiB for global area\n", __func__,
129             (unsigned long)selected_size / SZ_1M);
130
131        dma_declare_contiguous(NULL, selected_size, 0, limit);
132    }
133};
134
135static DEFINE_MUTEX(cma_mutex);
136
137static __init int cma_activate_area(unsigned long base_pfn, unsigned long count)
138{
139    unsigned long pfn = base_pfn;
140    unsigned i = count >> pageblock_order;
141    struct zone *zone;
142
143    WARN_ON_ONCE(!pfn_valid(pfn));
144    zone = page_zone(pfn_to_page(pfn));
145
146    do {
147        unsigned j;
148        base_pfn = pfn;
149        for (j = pageblock_nr_pages; j; --j, pfn++) {
150            WARN_ON_ONCE(!pfn_valid(pfn));
151            if (page_zone(pfn_to_page(pfn)) != zone)
152                return -EINVAL;
153        }
154        init_cma_reserved_pageblock(pfn_to_page(base_pfn));
155    } while (--i);
156    return 0;
157}
158
159static __init struct cma *cma_create_area(unsigned long base_pfn,
160                     unsigned long count)
161{
162    int bitmap_size = BITS_TO_LONGS(count) * sizeof(long);
163    struct cma *cma;
164    int ret = -ENOMEM;
165
166    pr_debug("%s(base %08lx, count %lx)\n", __func__, base_pfn, count);
167
168    cma = kmalloc(sizeof *cma, GFP_KERNEL);
169    if (!cma)
170        return ERR_PTR(-ENOMEM);
171
172    cma->base_pfn = base_pfn;
173    cma->count = count;
174    cma->bitmap = kzalloc(bitmap_size, GFP_KERNEL);
175
176    if (!cma->bitmap)
177        goto no_mem;
178
179    ret = cma_activate_area(base_pfn, count);
180    if (ret)
181        goto error;
182
183    pr_debug("%s: returned %p\n", __func__, (void *)cma);
184    return cma;
185
186error:
187    kfree(cma->bitmap);
188no_mem:
189    kfree(cma);
190    return ERR_PTR(ret);
191}
192
193static struct cma_reserved {
194    phys_addr_t start;
195    unsigned long size;
196    struct device *dev;
197} cma_reserved[MAX_CMA_AREAS] __initdata;
198static unsigned cma_reserved_count __initdata;
199
200static int __init cma_init_reserved_areas(void)
201{
202    struct cma_reserved *r = cma_reserved;
203    unsigned i = cma_reserved_count;
204
205    pr_debug("%s()\n", __func__);
206
207    for (; i; --i, ++r) {
208        struct cma *cma;
209        cma = cma_create_area(PFN_DOWN(r->start),
210                      r->size >> PAGE_SHIFT);
211        if (!IS_ERR(cma))
212            dev_set_cma_area(r->dev, cma);
213    }
214    return 0;
215}
216core_initcall(cma_init_reserved_areas);
217
218/**
219 * dma_declare_contiguous() - reserve area for contiguous memory handling
220 * for particular device
221 * @dev: Pointer to device structure.
222 * @size: Size of the reserved memory.
223 * @base: Start address of the reserved memory (optional, 0 for any).
224 * @limit: End address of the reserved memory (optional, 0 for any).
225 *
226 * This function reserves memory for specified device. It should be
227 * called by board specific code when early allocator (memblock or bootmem)
228 * is still activate.
229 */
230int __init dma_declare_contiguous(struct device *dev, phys_addr_t size,
231                  phys_addr_t base, phys_addr_t limit)
232{
233    struct cma_reserved *r = &cma_reserved[cma_reserved_count];
234    phys_addr_t alignment;
235
236    pr_debug("%s(size %lx, base %08lx, limit %08lx)\n", __func__,
237         (unsigned long)size, (unsigned long)base,
238         (unsigned long)limit);
239
240    /* Sanity checks */
241    if (cma_reserved_count == ARRAY_SIZE(cma_reserved)) {
242        pr_err("Not enough slots for CMA reserved regions!\n");
243        return -ENOSPC;
244    }
245
246    if (!size)
247        return -EINVAL;
248
249    /* Sanitise input arguments */
250    alignment = PAGE_SIZE << max(MAX_ORDER - 1, pageblock_order);
251    base = ALIGN(base, alignment);
252    size = ALIGN(size, alignment);
253    limit &= ~(alignment - 1);
254
255    /* Reserve memory */
256    if (base) {
257        if (memblock_is_region_reserved(base, size) ||
258            memblock_reserve(base, size) < 0) {
259            base = -EBUSY;
260            goto err;
261        }
262    } else {
263        /*
264         * Use __memblock_alloc_base() since
265         * memblock_alloc_base() panic()s.
266         */
267        phys_addr_t addr = __memblock_alloc_base(size, alignment, limit);
268        if (!addr) {
269            base = -ENOMEM;
270            goto err;
271        } else {
272            base = addr;
273        }
274    }
275
276    /*
277     * Each reserved area must be initialised later, when more kernel
278     * subsystems (like slab allocator) are available.
279     */
280    r->start = base;
281    r->size = size;
282    r->dev = dev;
283    cma_reserved_count++;
284    pr_info("CMA: reserved %ld MiB at %08lx\n", (unsigned long)size / SZ_1M,
285        (unsigned long)base);
286
287    /* Architecture specific contiguous memory fixup. */
288    dma_contiguous_early_fixup(base, size);
289    return 0;
290err:
291    pr_err("CMA: failed to reserve %ld MiB\n", (unsigned long)size / SZ_1M);
292    return base;
293}
294
295/**
296 * dma_alloc_from_contiguous() - allocate pages from contiguous area
297 * @dev: Pointer to device for which the allocation is performed.
298 * @count: Requested number of pages.
299 * @align: Requested alignment of pages (in PAGE_SIZE order).
300 *
301 * This function allocates memory buffer for specified device. It uses
302 * device specific contiguous memory area if available or the default
303 * global one. Requires architecture specific get_dev_cma_area() helper
304 * function.
305 */
306struct page *dma_alloc_from_contiguous(struct device *dev, int count,
307                       unsigned int align)
308{
309    unsigned long mask, pfn, pageno, start = 0;
310    struct cma *cma = dev_get_cma_area(dev);
311    struct page *page = NULL;
312    int ret;
313
314    if (!cma || !cma->count)
315        return NULL;
316
317    if (align > CONFIG_CMA_ALIGNMENT)
318        align = CONFIG_CMA_ALIGNMENT;
319
320    pr_debug("%s(cma %p, count %d, align %d)\n", __func__, (void *)cma,
321         count, align);
322
323    if (!count)
324        return NULL;
325
326    mask = (1 << align) - 1;
327
328    mutex_lock(&cma_mutex);
329
330    for (;;) {
331        pageno = bitmap_find_next_zero_area(cma->bitmap, cma->count,
332                            start, count, mask);
333        if (pageno >= cma->count)
334            break;
335
336        pfn = cma->base_pfn + pageno;
337        ret = alloc_contig_range(pfn, pfn + count, MIGRATE_CMA);
338        if (ret == 0) {
339            bitmap_set(cma->bitmap, pageno, count);
340            page = pfn_to_page(pfn);
341            break;
342        } else if (ret != -EBUSY) {
343            break;
344        }
345        pr_debug("%s(): memory range at %p is busy, retrying\n",
346             __func__, pfn_to_page(pfn));
347        /* try again with a bit different memory target */
348        start = pageno + mask + 1;
349    }
350
351    mutex_unlock(&cma_mutex);
352    pr_debug("%s(): returned %p\n", __func__, page);
353    return page;
354}
355
356/**
357 * dma_release_from_contiguous() - release allocated pages
358 * @dev: Pointer to device for which the pages were allocated.
359 * @pages: Allocated pages.
360 * @count: Number of allocated pages.
361 *
362 * This function releases memory allocated by dma_alloc_from_contiguous().
363 * It returns false when provided pages do not belong to contiguous area and
364 * true otherwise.
365 */
366bool dma_release_from_contiguous(struct device *dev, struct page *pages,
367                 int count)
368{
369    struct cma *cma = dev_get_cma_area(dev);
370    unsigned long pfn;
371
372    if (!cma || !pages)
373        return false;
374
375    pr_debug("%s(page %p)\n", __func__, (void *)pages);
376
377    pfn = page_to_pfn(pages);
378
379    if (pfn < cma->base_pfn || pfn >= cma->base_pfn + cma->count)
380        return false;
381
382    VM_BUG_ON(pfn + count > cma->base_pfn + cma->count);
383
384    mutex_lock(&cma_mutex);
385    bitmap_clear(cma->bitmap, pfn - cma->base_pfn, count);
386    free_contig_range(pfn, count);
387    mutex_unlock(&cma_mutex);
388
389    return true;
390}
391

Archive Download this file



interactive