1 // SPDX-License-Identifier: GPL-2.0
3 * Coherent per-device memory handling.
7 #include <linux/slab.h>
8 #include <linux/kernel.h>
9 #include <linux/module.h>
10 #include <linux/dma-mapping.h>
12 struct dma_coherent_mem {
14 dma_addr_t device_base;
15 unsigned long pfn_base;
17 unsigned long *bitmap;
19 bool use_dev_dma_pfn_offset;
22 static struct dma_coherent_mem *dma_coherent_default_memory __ro_after_init;
24 static inline struct dma_coherent_mem *dev_get_coherent_memory(struct device *dev)
26 if (dev && dev->dma_mem)
31 static inline dma_addr_t dma_get_device_base(struct device *dev,
32 struct dma_coherent_mem * mem)
34 if (mem->use_dev_dma_pfn_offset)
35 return (mem->pfn_base - dev->dma_pfn_offset) << PAGE_SHIFT;
37 return mem->device_base;
40 static int dma_init_coherent_memory(phys_addr_t phys_addr,
41 dma_addr_t device_addr, size_t size,
42 struct dma_coherent_mem **mem)
44 struct dma_coherent_mem *dma_mem = NULL;
45 void *mem_base = NULL;
46 int pages = size >> PAGE_SHIFT;
47 int bitmap_size = BITS_TO_LONGS(pages) * sizeof(long);
55 mem_base = memremap(phys_addr, size, MEMREMAP_WC);
60 dma_mem = kzalloc(sizeof(struct dma_coherent_mem), GFP_KERNEL);
65 dma_mem->bitmap = kzalloc(bitmap_size, GFP_KERNEL);
66 if (!dma_mem->bitmap) {
71 dma_mem->virt_base = mem_base;
72 dma_mem->device_base = device_addr;
73 dma_mem->pfn_base = PFN_DOWN(phys_addr);
74 dma_mem->size = pages;
75 spin_lock_init(&dma_mem->spinlock);
87 static void dma_release_coherent_memory(struct dma_coherent_mem *mem)
92 memunmap(mem->virt_base);
97 static int dma_assign_coherent_memory(struct device *dev,
98 struct dma_coherent_mem *mem)
110 int dma_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr,
111 dma_addr_t device_addr, size_t size)
113 struct dma_coherent_mem *mem;
116 ret = dma_init_coherent_memory(phys_addr, device_addr, size, &mem);
120 ret = dma_assign_coherent_memory(dev, mem);
122 dma_release_coherent_memory(mem);
126 static void *__dma_alloc_from_coherent(struct device *dev,
127 struct dma_coherent_mem *mem,
128 ssize_t size, dma_addr_t *dma_handle)
130 int order = get_order(size);
135 spin_lock_irqsave(&mem->spinlock, flags);
137 if (unlikely(size > ((dma_addr_t)mem->size << PAGE_SHIFT)))
140 pageno = bitmap_find_free_region(mem->bitmap, mem->size, order);
141 if (unlikely(pageno < 0))
145 * Memory was found in the coherent area.
147 *dma_handle = dma_get_device_base(dev, mem) +
148 ((dma_addr_t)pageno << PAGE_SHIFT);
149 ret = mem->virt_base + ((dma_addr_t)pageno << PAGE_SHIFT);
150 spin_unlock_irqrestore(&mem->spinlock, flags);
151 memset(ret, 0, size);
154 spin_unlock_irqrestore(&mem->spinlock, flags);
159 * dma_alloc_from_dev_coherent() - allocate memory from device coherent pool
160 * @dev: device from which we allocate memory
161 * @size: size of requested memory area
162 * @dma_handle: This will be filled with the correct dma handle
163 * @ret: This pointer will be filled with the virtual address
166 * This function should be only called from per-arch dma_alloc_coherent()
167 * to support allocation from per-device coherent memory pools.
169 * Returns 0 if dma_alloc_coherent should continue with allocating from
170 * generic memory areas, or !0 if dma_alloc_coherent should return @ret.
172 int dma_alloc_from_dev_coherent(struct device *dev, ssize_t size,
173 dma_addr_t *dma_handle, void **ret)
175 struct dma_coherent_mem *mem = dev_get_coherent_memory(dev);
180 *ret = __dma_alloc_from_coherent(dev, mem, size, dma_handle);
184 void *dma_alloc_from_global_coherent(struct device *dev, ssize_t size,
185 dma_addr_t *dma_handle)
187 if (!dma_coherent_default_memory)
190 return __dma_alloc_from_coherent(dev, dma_coherent_default_memory, size,
194 static int __dma_release_from_coherent(struct dma_coherent_mem *mem,
195 int order, void *vaddr)
197 if (mem && vaddr >= mem->virt_base && vaddr <
198 (mem->virt_base + ((dma_addr_t)mem->size << PAGE_SHIFT))) {
199 int page = (vaddr - mem->virt_base) >> PAGE_SHIFT;
202 spin_lock_irqsave(&mem->spinlock, flags);
203 bitmap_release_region(mem->bitmap, page, order);
204 spin_unlock_irqrestore(&mem->spinlock, flags);
211 * dma_release_from_dev_coherent() - free memory to device coherent memory pool
212 * @dev: device from which the memory was allocated
213 * @order: the order of pages allocated
214 * @vaddr: virtual address of allocated pages
216 * This checks whether the memory was allocated from the per-device
217 * coherent memory pool and if so, releases that memory.
219 * Returns 1 if we correctly released the memory, or 0 if the caller should
220 * proceed with releasing memory from generic pools.
222 int dma_release_from_dev_coherent(struct device *dev, int order, void *vaddr)
224 struct dma_coherent_mem *mem = dev_get_coherent_memory(dev);
226 return __dma_release_from_coherent(mem, order, vaddr);
229 int dma_release_from_global_coherent(int order, void *vaddr)
231 if (!dma_coherent_default_memory)
234 return __dma_release_from_coherent(dma_coherent_default_memory, order,
238 static int __dma_mmap_from_coherent(struct dma_coherent_mem *mem,
239 struct vm_area_struct *vma, void *vaddr, size_t size, int *ret)
241 if (mem && vaddr >= mem->virt_base && vaddr + size <=
242 (mem->virt_base + ((dma_addr_t)mem->size << PAGE_SHIFT))) {
243 unsigned long off = vma->vm_pgoff;
244 int start = (vaddr - mem->virt_base) >> PAGE_SHIFT;
245 unsigned long user_count = vma_pages(vma);
246 int count = PAGE_ALIGN(size) >> PAGE_SHIFT;
249 if (off < count && user_count <= count - off) {
250 unsigned long pfn = mem->pfn_base + start + off;
251 *ret = remap_pfn_range(vma, vma->vm_start, pfn,
252 user_count << PAGE_SHIFT,
261 * dma_mmap_from_dev_coherent() - mmap memory from the device coherent pool
262 * @dev: device from which the memory was allocated
263 * @vma: vm_area for the userspace memory
264 * @vaddr: cpu address returned by dma_alloc_from_dev_coherent
265 * @size: size of the memory buffer allocated
266 * @ret: result from remap_pfn_range()
268 * This checks whether the memory was allocated from the per-device
269 * coherent memory pool and if so, maps that memory to the provided vma.
271 * Returns 1 if @vaddr belongs to the device coherent pool and the caller
272 * should return @ret, or 0 if they should proceed with mapping memory from
275 int dma_mmap_from_dev_coherent(struct device *dev, struct vm_area_struct *vma,
276 void *vaddr, size_t size, int *ret)
278 struct dma_coherent_mem *mem = dev_get_coherent_memory(dev);
280 return __dma_mmap_from_coherent(mem, vma, vaddr, size, ret);
283 int dma_mmap_from_global_coherent(struct vm_area_struct *vma, void *vaddr,
284 size_t size, int *ret)
286 if (!dma_coherent_default_memory)
289 return __dma_mmap_from_coherent(dma_coherent_default_memory, vma,
294 * Support for reserved memory regions defined in device tree
296 #ifdef CONFIG_OF_RESERVED_MEM
297 #include <linux/of.h>
298 #include <linux/of_fdt.h>
299 #include <linux/of_reserved_mem.h>
301 static struct reserved_mem *dma_reserved_default_memory __initdata;
303 static int rmem_dma_device_init(struct reserved_mem *rmem, struct device *dev)
305 struct dma_coherent_mem *mem = rmem->priv;
309 ret = dma_init_coherent_memory(rmem->base, rmem->base,
312 pr_err("Reserved memory: failed to init DMA memory pool at %pa, size %ld MiB\n",
313 &rmem->base, (unsigned long)rmem->size / SZ_1M);
317 mem->use_dev_dma_pfn_offset = true;
319 dma_assign_coherent_memory(dev, mem);
323 static void rmem_dma_device_release(struct reserved_mem *rmem,
330 static const struct reserved_mem_ops rmem_dma_ops = {
331 .device_init = rmem_dma_device_init,
332 .device_release = rmem_dma_device_release,
335 static int __init rmem_dma_setup(struct reserved_mem *rmem)
337 unsigned long node = rmem->fdt_node;
339 if (of_get_flat_dt_prop(node, "reusable", NULL))
343 if (!of_get_flat_dt_prop(node, "no-map", NULL)) {
344 pr_err("Reserved memory: regions without no-map are not yet supported\n");
348 if (of_get_flat_dt_prop(node, "linux,dma-default", NULL)) {
349 WARN(dma_reserved_default_memory,
350 "Reserved memory: region for default DMA coherent area is redefined\n");
351 dma_reserved_default_memory = rmem;
355 rmem->ops = &rmem_dma_ops;
356 pr_info("Reserved memory: created DMA memory pool at %pa, size %ld MiB\n",
357 &rmem->base, (unsigned long)rmem->size / SZ_1M);
361 static int __init dma_init_reserved_memory(void)
363 const struct reserved_mem_ops *ops;
366 if (!dma_reserved_default_memory)
369 ops = dma_reserved_default_memory->ops;
372 * We rely on rmem_dma_device_init() does not propagate error of
373 * dma_assign_coherent_memory() for "NULL" device.
375 ret = ops->device_init(dma_reserved_default_memory, NULL);
378 dma_coherent_default_memory = dma_reserved_default_memory->priv;
379 pr_info("DMA: default coherent area is set\n");
385 core_initcall(dma_init_reserved_memory);
387 RESERVEDMEM_OF_DECLARE(dma, "shared-dma-pool", rmem_dma_setup);