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