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/dma-mapping.h>
  8
  9struct dma_coherent_mem {
 10	void		*virt_base;
 11	dma_addr_t	device_base;
 12	int		size;
 13	int		flags;
 14	unsigned long	*bitmap;
 15};
 16
 17int dma_declare_coherent_memory(struct device *dev, dma_addr_t bus_addr,
 18				dma_addr_t device_addr, size_t size, int flags)
 19{
 20	void __iomem *mem_base = NULL;
 21	int pages = size >> PAGE_SHIFT;
 22	int bitmap_size = BITS_TO_LONGS(pages) * sizeof(long);
 23
 24	if ((flags & (DMA_MEMORY_MAP | DMA_MEMORY_IO)) == 0)
 25		goto out;
 26	if (!size)
 27		goto out;
 28	if (dev->dma_mem)
 29		goto out;
 30
 31	/* FIXME: this routine just ignores DMA_MEMORY_INCLUDES_CHILDREN */
 32
 33	mem_base = ioremap(bus_addr, size);
 34	if (!mem_base)
 35		goto out;
 36
 37	dev->dma_mem = kzalloc(sizeof(struct dma_coherent_mem), GFP_KERNEL);
 38	if (!dev->dma_mem)
 39		goto out;
 40	dev->dma_mem->bitmap = kzalloc(bitmap_size, GFP_KERNEL);
 41	if (!dev->dma_mem->bitmap)
 42		goto free1_out;
 43
 44	dev->dma_mem->virt_base = mem_base;
 45	dev->dma_mem->device_base = device_addr;
 46	dev->dma_mem->size = pages;
 47	dev->dma_mem->flags = flags;
 48
 49	if (flags & DMA_MEMORY_MAP)
 50		return DMA_MEMORY_MAP;
 51
 52	return DMA_MEMORY_IO;
 53
 54 free1_out:
 55	kfree(dev->dma_mem);
 56 out:
 57	if (mem_base)
 58		iounmap(mem_base);
 59	return 0;
 60}
 61EXPORT_SYMBOL(dma_declare_coherent_memory);
 62
 63void dma_release_declared_memory(struct device *dev)
 64{
 65	struct dma_coherent_mem *mem = dev->dma_mem;
 66
 67	if (!mem)
 68		return;
 69	dev->dma_mem = NULL;
 70	iounmap(mem->virt_base);
 71	kfree(mem->bitmap);
 72	kfree(mem);
 73}
 74EXPORT_SYMBOL(dma_release_declared_memory);
 75
 76void *dma_mark_declared_memory_occupied(struct device *dev,
 77					dma_addr_t device_addr, size_t size)
 78{
 79	struct dma_coherent_mem *mem = dev->dma_mem;
 80	int pos, err;
 81
 82	size += device_addr & ~PAGE_MASK;
 83
 84	if (!mem)
 85		return ERR_PTR(-EINVAL);
 86
 87	pos = (device_addr - mem->device_base) >> PAGE_SHIFT;
 88	err = bitmap_allocate_region(mem->bitmap, pos, get_order(size));
 89	if (err != 0)
 90		return ERR_PTR(err);
 91	return mem->virt_base + (pos << PAGE_SHIFT);
 92}
 93EXPORT_SYMBOL(dma_mark_declared_memory_occupied);
 94
 95/**
 96 * dma_alloc_from_coherent() - try to allocate memory from the per-device coherent area
 97 *
 98 * @dev:	device from which we allocate memory
 99 * @size:	size of requested memory area
100 * @dma_handle:	This will be filled with the correct dma handle
101 * @ret:	This pointer will be filled with the virtual address
102 *		to allocated area.
103 *
104 * This function should be only called from per-arch dma_alloc_coherent()
105 * to support allocation from per-device coherent memory pools.
106 *
107 * Returns 0 if dma_alloc_coherent should continue with allocating from
108 * generic memory areas, or !0 if dma_alloc_coherent should return @ret.
109 */
110int dma_alloc_from_coherent(struct device *dev, ssize_t size,
111				       dma_addr_t *dma_handle, void **ret)
112{
113	struct dma_coherent_mem *mem;
114	int order = get_order(size);
115	int pageno;
116
117	if (!dev)
118		return 0;
119	mem = dev->dma_mem;
120	if (!mem)
121		return 0;
122
123	*ret = NULL;
124
125	if (unlikely(size > (mem->size << PAGE_SHIFT)))
126		goto err;
127
128	pageno = bitmap_find_free_region(mem->bitmap, mem->size, order);
129	if (unlikely(pageno < 0))
130		goto err;
131
132	/*
133	 * Memory was found in the per-device area.
134	 */
135	*dma_handle = mem->device_base + (pageno << PAGE_SHIFT);
136	*ret = mem->virt_base + (pageno << PAGE_SHIFT);
137	memset(*ret, 0, size);
138
139	return 1;
140
141err:
142	/*
143	 * In the case where the allocation can not be satisfied from the
144	 * per-device area, try to fall back to generic memory if the
145	 * constraints allow it.
146	 */
147	return mem->flags & DMA_MEMORY_EXCLUSIVE;
148}
149EXPORT_SYMBOL(dma_alloc_from_coherent);
150
151/**
152 * dma_release_from_coherent() - try to free the memory allocated from per-device coherent memory pool
153 * @dev:	device from which the memory was allocated
154 * @order:	the order of pages allocated
155 * @vaddr:	virtual address of allocated pages
156 *
157 * This checks whether the memory was allocated from the per-device
158 * coherent memory pool and if so, releases that memory.
159 *
160 * Returns 1 if we correctly released the memory, or 0 if
161 * dma_release_coherent() should proceed with releasing memory from
162 * generic pools.
163 */
164int dma_release_from_coherent(struct device *dev, int order, void *vaddr)
165{
166	struct dma_coherent_mem *mem = dev ? dev->dma_mem : NULL;
167
168	if (mem && vaddr >= mem->virt_base && vaddr <
169		   (mem->virt_base + (mem->size << PAGE_SHIFT))) {
170		int page = (vaddr - mem->virt_base) >> PAGE_SHIFT;
171
172		bitmap_release_region(mem->bitmap, page, order);
173		return 1;
174	}
175	return 0;
176}
177EXPORT_SYMBOL(dma_release_from_coherent);