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