1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Coherent per-device memory handling. 4 * Borrowed from i386 5 */ 6 #include <linux/io.h> 7 #include <linux/slab.h> 8 #include <linux/kernel.h> 9 #include <linux/module.h> 10 #include <linux/dma-mapping.h> 11 12 struct dma_coherent_mem { 13 void *virt_base; 14 dma_addr_t device_base; 15 unsigned long pfn_base; 16 int size; 17 int flags; 18 unsigned long *bitmap; 19 spinlock_t spinlock; 20 bool use_dev_dma_pfn_offset; 21 }; 22 23 static struct dma_coherent_mem *dma_coherent_default_memory __ro_after_init; 24 25 static inline struct dma_coherent_mem *dev_get_coherent_memory(struct device *dev) 26 { 27 if (dev && dev->dma_mem) 28 return dev->dma_mem; 29 return NULL; 30 } 31 32 static inline dma_addr_t dma_get_device_base(struct device *dev, 33 struct dma_coherent_mem * mem) 34 { 35 if (mem->use_dev_dma_pfn_offset) 36 return (mem->pfn_base - dev->dma_pfn_offset) << PAGE_SHIFT; 37 else 38 return mem->device_base; 39 } 40 41 static int dma_init_coherent_memory( 42 phys_addr_t phys_addr, dma_addr_t device_addr, size_t size, int flags, 43 struct dma_coherent_mem **mem) 44 { 45 struct dma_coherent_mem *dma_mem = NULL; 46 void __iomem *mem_base = NULL; 47 int pages = size >> PAGE_SHIFT; 48 int bitmap_size = BITS_TO_LONGS(pages) * sizeof(long); 49 int ret; 50 51 if (!size) { 52 ret = -EINVAL; 53 goto out; 54 } 55 56 mem_base = memremap(phys_addr, size, MEMREMAP_WC); 57 if (!mem_base) { 58 ret = -EINVAL; 59 goto out; 60 } 61 dma_mem = kzalloc(sizeof(struct dma_coherent_mem), GFP_KERNEL); 62 if (!dma_mem) { 63 ret = -ENOMEM; 64 goto out; 65 } 66 dma_mem->bitmap = kzalloc(bitmap_size, GFP_KERNEL); 67 if (!dma_mem->bitmap) { 68 ret = -ENOMEM; 69 goto out; 70 } 71 72 dma_mem->virt_base = mem_base; 73 dma_mem->device_base = device_addr; 74 dma_mem->pfn_base = PFN_DOWN(phys_addr); 75 dma_mem->size = pages; 76 dma_mem->flags = flags; 77 spin_lock_init(&dma_mem->spinlock); 78 79 *mem = dma_mem; 80 return 0; 81 82 out: 83 kfree(dma_mem); 84 if (mem_base) 85 memunmap(mem_base); 86 return ret; 87 } 88 89 static void dma_release_coherent_memory(struct dma_coherent_mem *mem) 90 { 91 if (!mem) 92 return; 93 94 memunmap(mem->virt_base); 95 kfree(mem->bitmap); 96 kfree(mem); 97 } 98 99 static int dma_assign_coherent_memory(struct device *dev, 100 struct dma_coherent_mem *mem) 101 { 102 if (!dev) 103 return -ENODEV; 104 105 if (dev->dma_mem) 106 return -EBUSY; 107 108 dev->dma_mem = mem; 109 return 0; 110 } 111 112 int dma_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr, 113 dma_addr_t device_addr, size_t size, int flags) 114 { 115 struct dma_coherent_mem *mem; 116 int ret; 117 118 ret = dma_init_coherent_memory(phys_addr, device_addr, size, flags, &mem); 119 if (ret) 120 return ret; 121 122 ret = dma_assign_coherent_memory(dev, mem); 123 if (ret) 124 dma_release_coherent_memory(mem); 125 return ret; 126 } 127 EXPORT_SYMBOL(dma_declare_coherent_memory); 128 129 void dma_release_declared_memory(struct device *dev) 130 { 131 struct dma_coherent_mem *mem = dev->dma_mem; 132 133 if (!mem) 134 return; 135 dma_release_coherent_memory(mem); 136 dev->dma_mem = NULL; 137 } 138 EXPORT_SYMBOL(dma_release_declared_memory); 139 140 void *dma_mark_declared_memory_occupied(struct device *dev, 141 dma_addr_t device_addr, size_t size) 142 { 143 struct dma_coherent_mem *mem = dev->dma_mem; 144 unsigned long flags; 145 int pos, err; 146 147 size += device_addr & ~PAGE_MASK; 148 149 if (!mem) 150 return ERR_PTR(-EINVAL); 151 152 spin_lock_irqsave(&mem->spinlock, flags); 153 pos = PFN_DOWN(device_addr - dma_get_device_base(dev, mem)); 154 err = bitmap_allocate_region(mem->bitmap, pos, get_order(size)); 155 spin_unlock_irqrestore(&mem->spinlock, flags); 156 157 if (err != 0) 158 return ERR_PTR(err); 159 return mem->virt_base + (pos << PAGE_SHIFT); 160 } 161 EXPORT_SYMBOL(dma_mark_declared_memory_occupied); 162 163 static void *__dma_alloc_from_coherent(struct dma_coherent_mem *mem, 164 ssize_t size, dma_addr_t *dma_handle) 165 { 166 int order = get_order(size); 167 unsigned long flags; 168 int pageno; 169 void *ret; 170 171 spin_lock_irqsave(&mem->spinlock, flags); 172 173 if (unlikely(size > (mem->size << PAGE_SHIFT))) 174 goto err; 175 176 pageno = bitmap_find_free_region(mem->bitmap, mem->size, order); 177 if (unlikely(pageno < 0)) 178 goto err; 179 180 /* 181 * Memory was found in the coherent area. 182 */ 183 *dma_handle = mem->device_base + (pageno << PAGE_SHIFT); 184 ret = mem->virt_base + (pageno << PAGE_SHIFT); 185 spin_unlock_irqrestore(&mem->spinlock, flags); 186 memset(ret, 0, size); 187 return ret; 188 err: 189 spin_unlock_irqrestore(&mem->spinlock, flags); 190 return NULL; 191 } 192 193 /** 194 * dma_alloc_from_dev_coherent() - allocate memory from device coherent pool 195 * @dev: device from which we allocate memory 196 * @size: size of requested memory area 197 * @dma_handle: This will be filled with the correct dma handle 198 * @ret: This pointer will be filled with the virtual address 199 * to allocated area. 200 * 201 * This function should be only called from per-arch dma_alloc_coherent() 202 * to support allocation from per-device coherent memory pools. 203 * 204 * Returns 0 if dma_alloc_coherent should continue with allocating from 205 * generic memory areas, or !0 if dma_alloc_coherent should return @ret. 206 */ 207 int dma_alloc_from_dev_coherent(struct device *dev, ssize_t size, 208 dma_addr_t *dma_handle, void **ret) 209 { 210 struct dma_coherent_mem *mem = dev_get_coherent_memory(dev); 211 212 if (!mem) 213 return 0; 214 215 *ret = __dma_alloc_from_coherent(mem, size, dma_handle); 216 if (*ret) 217 return 1; 218 219 /* 220 * In the case where the allocation can not be satisfied from the 221 * per-device area, try to fall back to generic memory if the 222 * constraints allow it. 223 */ 224 return mem->flags & DMA_MEMORY_EXCLUSIVE; 225 } 226 EXPORT_SYMBOL(dma_alloc_from_dev_coherent); 227 228 void *dma_alloc_from_global_coherent(ssize_t size, dma_addr_t *dma_handle) 229 { 230 if (!dma_coherent_default_memory) 231 return NULL; 232 233 return __dma_alloc_from_coherent(dma_coherent_default_memory, size, 234 dma_handle); 235 } 236 237 static int __dma_release_from_coherent(struct dma_coherent_mem *mem, 238 int order, void *vaddr) 239 { 240 if (mem && vaddr >= mem->virt_base && vaddr < 241 (mem->virt_base + (mem->size << PAGE_SHIFT))) { 242 int page = (vaddr - mem->virt_base) >> PAGE_SHIFT; 243 unsigned long flags; 244 245 spin_lock_irqsave(&mem->spinlock, flags); 246 bitmap_release_region(mem->bitmap, page, order); 247 spin_unlock_irqrestore(&mem->spinlock, flags); 248 return 1; 249 } 250 return 0; 251 } 252 253 /** 254 * dma_release_from_dev_coherent() - free memory to device coherent memory pool 255 * @dev: device from which the memory was allocated 256 * @order: the order of pages allocated 257 * @vaddr: virtual address of allocated pages 258 * 259 * This checks whether the memory was allocated from the per-device 260 * coherent memory pool and if so, releases that memory. 261 * 262 * Returns 1 if we correctly released the memory, or 0 if the caller should 263 * proceed with releasing memory from generic pools. 264 */ 265 int dma_release_from_dev_coherent(struct device *dev, int order, void *vaddr) 266 { 267 struct dma_coherent_mem *mem = dev_get_coherent_memory(dev); 268 269 return __dma_release_from_coherent(mem, order, vaddr); 270 } 271 EXPORT_SYMBOL(dma_release_from_dev_coherent); 272 273 int dma_release_from_global_coherent(int order, void *vaddr) 274 { 275 if (!dma_coherent_default_memory) 276 return 0; 277 278 return __dma_release_from_coherent(dma_coherent_default_memory, order, 279 vaddr); 280 } 281 282 static int __dma_mmap_from_coherent(struct dma_coherent_mem *mem, 283 struct vm_area_struct *vma, void *vaddr, size_t size, int *ret) 284 { 285 if (mem && vaddr >= mem->virt_base && vaddr + size <= 286 (mem->virt_base + (mem->size << PAGE_SHIFT))) { 287 unsigned long off = vma->vm_pgoff; 288 int start = (vaddr - mem->virt_base) >> PAGE_SHIFT; 289 int user_count = vma_pages(vma); 290 int count = PAGE_ALIGN(size) >> PAGE_SHIFT; 291 292 *ret = -ENXIO; 293 if (off < count && user_count <= count - off) { 294 unsigned long pfn = mem->pfn_base + start + off; 295 *ret = remap_pfn_range(vma, vma->vm_start, pfn, 296 user_count << PAGE_SHIFT, 297 vma->vm_page_prot); 298 } 299 return 1; 300 } 301 return 0; 302 } 303 304 /** 305 * dma_mmap_from_dev_coherent() - mmap memory from the device coherent pool 306 * @dev: device from which the memory was allocated 307 * @vma: vm_area for the userspace memory 308 * @vaddr: cpu address returned by dma_alloc_from_dev_coherent 309 * @size: size of the memory buffer allocated 310 * @ret: result from remap_pfn_range() 311 * 312 * This checks whether the memory was allocated from the per-device 313 * coherent memory pool and if so, maps that memory to the provided vma. 314 * 315 * Returns 1 if @vaddr belongs to the device coherent pool and the caller 316 * should return @ret, or 0 if they should proceed with mapping memory from 317 * generic areas. 318 */ 319 int dma_mmap_from_dev_coherent(struct device *dev, struct vm_area_struct *vma, 320 void *vaddr, size_t size, int *ret) 321 { 322 struct dma_coherent_mem *mem = dev_get_coherent_memory(dev); 323 324 return __dma_mmap_from_coherent(mem, vma, vaddr, size, ret); 325 } 326 EXPORT_SYMBOL(dma_mmap_from_dev_coherent); 327 328 int dma_mmap_from_global_coherent(struct vm_area_struct *vma, void *vaddr, 329 size_t size, int *ret) 330 { 331 if (!dma_coherent_default_memory) 332 return 0; 333 334 return __dma_mmap_from_coherent(dma_coherent_default_memory, vma, 335 vaddr, size, ret); 336 } 337 338 /* 339 * Support for reserved memory regions defined in device tree 340 */ 341 #ifdef CONFIG_OF_RESERVED_MEM 342 #include <linux/of.h> 343 #include <linux/of_fdt.h> 344 #include <linux/of_reserved_mem.h> 345 346 static struct reserved_mem *dma_reserved_default_memory __initdata; 347 348 static int rmem_dma_device_init(struct reserved_mem *rmem, struct device *dev) 349 { 350 struct dma_coherent_mem *mem = rmem->priv; 351 int ret; 352 353 if (!mem) { 354 ret = dma_init_coherent_memory(rmem->base, rmem->base, 355 rmem->size, 356 DMA_MEMORY_EXCLUSIVE, &mem); 357 if (ret) { 358 pr_err("Reserved memory: failed to init DMA memory pool at %pa, size %ld MiB\n", 359 &rmem->base, (unsigned long)rmem->size / SZ_1M); 360 return ret; 361 } 362 } 363 mem->use_dev_dma_pfn_offset = true; 364 rmem->priv = mem; 365 dma_assign_coherent_memory(dev, mem); 366 return 0; 367 } 368 369 static void rmem_dma_device_release(struct reserved_mem *rmem, 370 struct device *dev) 371 { 372 if (dev) 373 dev->dma_mem = NULL; 374 } 375 376 static const struct reserved_mem_ops rmem_dma_ops = { 377 .device_init = rmem_dma_device_init, 378 .device_release = rmem_dma_device_release, 379 }; 380 381 static int __init rmem_dma_setup(struct reserved_mem *rmem) 382 { 383 unsigned long node = rmem->fdt_node; 384 385 if (of_get_flat_dt_prop(node, "reusable", NULL)) 386 return -EINVAL; 387 388 #ifdef CONFIG_ARM 389 if (!of_get_flat_dt_prop(node, "no-map", NULL)) { 390 pr_err("Reserved memory: regions without no-map are not yet supported\n"); 391 return -EINVAL; 392 } 393 394 if (of_get_flat_dt_prop(node, "linux,dma-default", NULL)) { 395 WARN(dma_reserved_default_memory, 396 "Reserved memory: region for default DMA coherent area is redefined\n"); 397 dma_reserved_default_memory = rmem; 398 } 399 #endif 400 401 rmem->ops = &rmem_dma_ops; 402 pr_info("Reserved memory: created DMA memory pool at %pa, size %ld MiB\n", 403 &rmem->base, (unsigned long)rmem->size / SZ_1M); 404 return 0; 405 } 406 407 static int __init dma_init_reserved_memory(void) 408 { 409 const struct reserved_mem_ops *ops; 410 int ret; 411 412 if (!dma_reserved_default_memory) 413 return -ENOMEM; 414 415 ops = dma_reserved_default_memory->ops; 416 417 /* 418 * We rely on rmem_dma_device_init() does not propagate error of 419 * dma_assign_coherent_memory() for "NULL" device. 420 */ 421 ret = ops->device_init(dma_reserved_default_memory, NULL); 422 423 if (!ret) { 424 dma_coherent_default_memory = dma_reserved_default_memory->priv; 425 pr_info("DMA: default coherent area is set\n"); 426 } 427 428 return ret; 429 } 430 431 core_initcall(dma_init_reserved_memory); 432 433 RESERVEDMEM_OF_DECLARE(dma, "shared-dma-pool", rmem_dma_setup); 434 #endif 435