Root/drivers/base/dma-coherent.c

1/*
2 * Coherent per-device memory handling.
3 * Borrowed from i386
4 */
5#include <linux/slab.h>
6#include <linux/kernel.h>
7#include <linux/module.h>
8#include <linux/dma-mapping.h>
9
10struct dma_coherent_mem {
11    void *virt_base;
12    dma_addr_t device_base;
13    phys_addr_t pfn_base;
14    int size;
15    int flags;
16    unsigned long *bitmap;
17};
18
19int dma_declare_coherent_memory(struct device *dev, dma_addr_t bus_addr,
20                dma_addr_t device_addr, size_t size, int flags)
21{
22    void __iomem *mem_base = NULL;
23    int pages = size >> PAGE_SHIFT;
24    int bitmap_size = BITS_TO_LONGS(pages) * sizeof(long);
25
26    if ((flags & (DMA_MEMORY_MAP | DMA_MEMORY_IO)) == 0)
27        goto out;
28    if (!size)
29        goto out;
30    if (dev->dma_mem)
31        goto out;
32
33    /* FIXME: this routine just ignores DMA_MEMORY_INCLUDES_CHILDREN */
34
35    mem_base = ioremap(bus_addr, size);
36    if (!mem_base)
37        goto out;
38
39    dev->dma_mem = kzalloc(sizeof(struct dma_coherent_mem), GFP_KERNEL);
40    if (!dev->dma_mem)
41        goto out;
42    dev->dma_mem->bitmap = kzalloc(bitmap_size, GFP_KERNEL);
43    if (!dev->dma_mem->bitmap)
44        goto free1_out;
45
46    dev->dma_mem->virt_base = mem_base;
47    dev->dma_mem->device_base = device_addr;
48    dev->dma_mem->pfn_base = PFN_DOWN(bus_addr);
49    dev->dma_mem->size = pages;
50    dev->dma_mem->flags = flags;
51
52    if (flags & DMA_MEMORY_MAP)
53        return DMA_MEMORY_MAP;
54
55    return DMA_MEMORY_IO;
56
57 free1_out:
58    kfree(dev->dma_mem);
59 out:
60    if (mem_base)
61        iounmap(mem_base);
62    return 0;
63}
64EXPORT_SYMBOL(dma_declare_coherent_memory);
65
66void dma_release_declared_memory(struct device *dev)
67{
68    struct dma_coherent_mem *mem = dev->dma_mem;
69
70    if (!mem)
71        return;
72    dev->dma_mem = NULL;
73    iounmap(mem->virt_base);
74    kfree(mem->bitmap);
75    kfree(mem);
76}
77EXPORT_SYMBOL(dma_release_declared_memory);
78
79void *dma_mark_declared_memory_occupied(struct device *dev,
80                    dma_addr_t device_addr, size_t size)
81{
82    struct dma_coherent_mem *mem = dev->dma_mem;
83    int pos, err;
84
85    size += device_addr & ~PAGE_MASK;
86
87    if (!mem)
88        return ERR_PTR(-EINVAL);
89
90    pos = (device_addr - mem->device_base) >> PAGE_SHIFT;
91    err = bitmap_allocate_region(mem->bitmap, pos, get_order(size));
92    if (err != 0)
93        return ERR_PTR(err);
94    return mem->virt_base + (pos << PAGE_SHIFT);
95}
96EXPORT_SYMBOL(dma_mark_declared_memory_occupied);
97
98/**
99 * dma_alloc_from_coherent() - try to allocate memory from the per-device coherent area
100 *
101 * @dev: device from which we allocate memory
102 * @size: size of requested memory area
103 * @dma_handle: This will be filled with the correct dma handle
104 * @ret: This pointer will be filled with the virtual address
105 * to allocated area.
106 *
107 * This function should be only called from per-arch dma_alloc_coherent()
108 * to support allocation from per-device coherent memory pools.
109 *
110 * Returns 0 if dma_alloc_coherent should continue with allocating from
111 * generic memory areas, or !0 if dma_alloc_coherent should return @ret.
112 */
113int dma_alloc_from_coherent(struct device *dev, ssize_t size,
114                       dma_addr_t *dma_handle, void **ret)
115{
116    struct dma_coherent_mem *mem;
117    int order = get_order(size);
118    int pageno;
119
120    if (!dev)
121        return 0;
122    mem = dev->dma_mem;
123    if (!mem)
124        return 0;
125
126    *ret = NULL;
127
128    if (unlikely(size > (mem->size << PAGE_SHIFT)))
129        goto err;
130
131    pageno = bitmap_find_free_region(mem->bitmap, mem->size, order);
132    if (unlikely(pageno < 0))
133        goto err;
134
135    /*
136     * Memory was found in the per-device area.
137     */
138    *dma_handle = mem->device_base + (pageno << PAGE_SHIFT);
139    *ret = mem->virt_base + (pageno << PAGE_SHIFT);
140    memset(*ret, 0, size);
141
142    return 1;
143
144err:
145    /*
146     * In the case where the allocation can not be satisfied from the
147     * per-device area, try to fall back to generic memory if the
148     * constraints allow it.
149     */
150    return mem->flags & DMA_MEMORY_EXCLUSIVE;
151}
152EXPORT_SYMBOL(dma_alloc_from_coherent);
153
154/**
155 * dma_release_from_coherent() - try to free the memory allocated from per-device coherent memory pool
156 * @dev: device from which the memory was allocated
157 * @order: the order of pages allocated
158 * @vaddr: virtual address of allocated pages
159 *
160 * This checks whether the memory was allocated from the per-device
161 * coherent memory pool and if so, releases that memory.
162 *
163 * Returns 1 if we correctly released the memory, or 0 if
164 * dma_release_coherent() should proceed with releasing memory from
165 * generic pools.
166 */
167int dma_release_from_coherent(struct device *dev, int order, void *vaddr)
168{
169    struct dma_coherent_mem *mem = dev ? dev->dma_mem : NULL;
170
171    if (mem && vaddr >= mem->virt_base && vaddr <
172           (mem->virt_base + (mem->size << PAGE_SHIFT))) {
173        int page = (vaddr - mem->virt_base) >> PAGE_SHIFT;
174
175        bitmap_release_region(mem->bitmap, page, order);
176        return 1;
177    }
178    return 0;
179}
180EXPORT_SYMBOL(dma_release_from_coherent);
181
182/**
183 * dma_mmap_from_coherent() - try to mmap the memory allocated from
184 * per-device coherent memory pool to userspace
185 * @dev: device from which the memory was allocated
186 * @vma: vm_area for the userspace memory
187 * @vaddr: cpu address returned by dma_alloc_from_coherent
188 * @size: size of the memory buffer allocated by dma_alloc_from_coherent
189 * @ret: result from remap_pfn_range()
190 *
191 * This checks whether the memory was allocated from the per-device
192 * coherent memory pool and if so, maps that memory to the provided vma.
193 *
194 * Returns 1 if we correctly mapped the memory, or 0 if
195 * dma_release_coherent() should proceed with mapping memory from
196 * generic pools.
197 */
198int dma_mmap_from_coherent(struct device *dev, struct vm_area_struct *vma,
199               void *vaddr, size_t size, int *ret)
200{
201    struct dma_coherent_mem *mem = dev ? dev->dma_mem : NULL;
202
203    if (mem && vaddr >= mem->virt_base && vaddr + size <=
204           (mem->virt_base + (mem->size << PAGE_SHIFT))) {
205        unsigned long off = vma->vm_pgoff;
206        int start = (vaddr - mem->virt_base) >> PAGE_SHIFT;
207        int user_count = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
208        int count = size >> PAGE_SHIFT;
209
210        *ret = -ENXIO;
211        if (off < count && user_count <= count - off) {
212            unsigned pfn = mem->pfn_base + start + off;
213            *ret = remap_pfn_range(vma, vma->vm_start, pfn,
214                           user_count << PAGE_SHIFT,
215                           vma->vm_page_prot);
216        }
217        return 1;
218    }
219    return 0;
220}
221EXPORT_SYMBOL(dma_mmap_from_coherent);
222

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