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 #include <linux/dma-map-ops.h> 12 13 struct dma_coherent_mem { 14 void *virt_base; 15 dma_addr_t device_base; 16 unsigned long pfn_base; 17 int size; 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 phys_to_dma(dev, PFN_PHYS(mem->pfn_base)); 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 /* 111 * Declare a region of memory to be handed out by dma_alloc_coherent() when it 112 * is asked for coherent memory for this device. This shall only be used 113 * from platform code, usually based on the device tree description. 114 * 115 * phys_addr is the CPU physical address to which the memory is currently 116 * assigned (this will be ioremapped so the CPU can access the region). 117 * 118 * device_addr is the DMA address the device needs to be programmed with to 119 * actually address this memory (this will be handed out as the dma_addr_t in 120 * dma_alloc_coherent()). 121 * 122 * size is the size of the area (must be a multiple of PAGE_SIZE). 123 * 124 * As a simplification for the platforms, only *one* such region of memory may 125 * be declared per device. 126 */ 127 int dma_declare_coherent_memory(struct device *dev, phys_addr_t phys_addr, 128 dma_addr_t device_addr, size_t size) 129 { 130 struct dma_coherent_mem *mem; 131 int ret; 132 133 ret = dma_init_coherent_memory(phys_addr, device_addr, size, &mem); 134 if (ret) 135 return ret; 136 137 ret = dma_assign_coherent_memory(dev, mem); 138 if (ret) 139 dma_release_coherent_memory(mem); 140 return ret; 141 } 142 143 static void *__dma_alloc_from_coherent(struct device *dev, 144 struct dma_coherent_mem *mem, 145 ssize_t size, dma_addr_t *dma_handle) 146 { 147 int order = get_order(size); 148 unsigned long flags; 149 int pageno; 150 void *ret; 151 152 spin_lock_irqsave(&mem->spinlock, flags); 153 154 if (unlikely(size > ((dma_addr_t)mem->size << PAGE_SHIFT))) 155 goto err; 156 157 pageno = bitmap_find_free_region(mem->bitmap, mem->size, order); 158 if (unlikely(pageno < 0)) 159 goto err; 160 161 /* 162 * Memory was found in the coherent area. 163 */ 164 *dma_handle = dma_get_device_base(dev, mem) + 165 ((dma_addr_t)pageno << PAGE_SHIFT); 166 ret = mem->virt_base + ((dma_addr_t)pageno << PAGE_SHIFT); 167 spin_unlock_irqrestore(&mem->spinlock, flags); 168 memset(ret, 0, size); 169 return ret; 170 err: 171 spin_unlock_irqrestore(&mem->spinlock, flags); 172 return NULL; 173 } 174 175 /** 176 * dma_alloc_from_dev_coherent() - allocate memory from device coherent pool 177 * @dev: device from which we allocate memory 178 * @size: size of requested memory area 179 * @dma_handle: This will be filled with the correct dma handle 180 * @ret: This pointer will be filled with the virtual address 181 * to allocated area. 182 * 183 * This function should be only called from per-arch dma_alloc_coherent() 184 * to support allocation from per-device coherent memory pools. 185 * 186 * Returns 0 if dma_alloc_coherent should continue with allocating from 187 * generic memory areas, or !0 if dma_alloc_coherent should return @ret. 188 */ 189 int dma_alloc_from_dev_coherent(struct device *dev, ssize_t size, 190 dma_addr_t *dma_handle, void **ret) 191 { 192 struct dma_coherent_mem *mem = dev_get_coherent_memory(dev); 193 194 if (!mem) 195 return 0; 196 197 *ret = __dma_alloc_from_coherent(dev, mem, size, dma_handle); 198 return 1; 199 } 200 201 void *dma_alloc_from_global_coherent(struct device *dev, ssize_t size, 202 dma_addr_t *dma_handle) 203 { 204 if (!dma_coherent_default_memory) 205 return NULL; 206 207 return __dma_alloc_from_coherent(dev, dma_coherent_default_memory, size, 208 dma_handle); 209 } 210 211 static int __dma_release_from_coherent(struct dma_coherent_mem *mem, 212 int order, void *vaddr) 213 { 214 if (mem && vaddr >= mem->virt_base && vaddr < 215 (mem->virt_base + ((dma_addr_t)mem->size << PAGE_SHIFT))) { 216 int page = (vaddr - mem->virt_base) >> PAGE_SHIFT; 217 unsigned long flags; 218 219 spin_lock_irqsave(&mem->spinlock, flags); 220 bitmap_release_region(mem->bitmap, page, order); 221 spin_unlock_irqrestore(&mem->spinlock, flags); 222 return 1; 223 } 224 return 0; 225 } 226 227 /** 228 * dma_release_from_dev_coherent() - free memory to device coherent memory pool 229 * @dev: device from which the memory was allocated 230 * @order: the order of pages allocated 231 * @vaddr: virtual address of allocated pages 232 * 233 * This checks whether the memory was allocated from the per-device 234 * coherent memory pool and if so, releases that memory. 235 * 236 * Returns 1 if we correctly released the memory, or 0 if the caller should 237 * proceed with releasing memory from generic pools. 238 */ 239 int dma_release_from_dev_coherent(struct device *dev, int order, void *vaddr) 240 { 241 struct dma_coherent_mem *mem = dev_get_coherent_memory(dev); 242 243 return __dma_release_from_coherent(mem, order, vaddr); 244 } 245 246 int dma_release_from_global_coherent(int order, void *vaddr) 247 { 248 if (!dma_coherent_default_memory) 249 return 0; 250 251 return __dma_release_from_coherent(dma_coherent_default_memory, order, 252 vaddr); 253 } 254 255 static int __dma_mmap_from_coherent(struct dma_coherent_mem *mem, 256 struct vm_area_struct *vma, void *vaddr, size_t size, int *ret) 257 { 258 if (mem && vaddr >= mem->virt_base && vaddr + size <= 259 (mem->virt_base + ((dma_addr_t)mem->size << PAGE_SHIFT))) { 260 unsigned long off = vma->vm_pgoff; 261 int start = (vaddr - mem->virt_base) >> PAGE_SHIFT; 262 unsigned long user_count = vma_pages(vma); 263 int count = PAGE_ALIGN(size) >> PAGE_SHIFT; 264 265 *ret = -ENXIO; 266 if (off < count && user_count <= count - off) { 267 unsigned long pfn = mem->pfn_base + start + off; 268 *ret = remap_pfn_range(vma, vma->vm_start, pfn, 269 user_count << PAGE_SHIFT, 270 vma->vm_page_prot); 271 } 272 return 1; 273 } 274 return 0; 275 } 276 277 /** 278 * dma_mmap_from_dev_coherent() - mmap memory from the device coherent pool 279 * @dev: device from which the memory was allocated 280 * @vma: vm_area for the userspace memory 281 * @vaddr: cpu address returned by dma_alloc_from_dev_coherent 282 * @size: size of the memory buffer allocated 283 * @ret: result from remap_pfn_range() 284 * 285 * This checks whether the memory was allocated from the per-device 286 * coherent memory pool and if so, maps that memory to the provided vma. 287 * 288 * Returns 1 if @vaddr belongs to the device coherent pool and the caller 289 * should return @ret, or 0 if they should proceed with mapping memory from 290 * generic areas. 291 */ 292 int dma_mmap_from_dev_coherent(struct device *dev, struct vm_area_struct *vma, 293 void *vaddr, size_t size, int *ret) 294 { 295 struct dma_coherent_mem *mem = dev_get_coherent_memory(dev); 296 297 return __dma_mmap_from_coherent(mem, vma, vaddr, size, ret); 298 } 299 300 int dma_mmap_from_global_coherent(struct vm_area_struct *vma, void *vaddr, 301 size_t size, int *ret) 302 { 303 if (!dma_coherent_default_memory) 304 return 0; 305 306 return __dma_mmap_from_coherent(dma_coherent_default_memory, vma, 307 vaddr, size, ret); 308 } 309 310 /* 311 * Support for reserved memory regions defined in device tree 312 */ 313 #ifdef CONFIG_OF_RESERVED_MEM 314 #include <linux/of.h> 315 #include <linux/of_fdt.h> 316 #include <linux/of_reserved_mem.h> 317 318 static struct reserved_mem *dma_reserved_default_memory __initdata; 319 320 static int rmem_dma_device_init(struct reserved_mem *rmem, struct device *dev) 321 { 322 struct dma_coherent_mem *mem = rmem->priv; 323 int ret; 324 325 if (!mem) { 326 ret = dma_init_coherent_memory(rmem->base, rmem->base, 327 rmem->size, &mem); 328 if (ret) { 329 pr_err("Reserved memory: failed to init DMA memory pool at %pa, size %ld MiB\n", 330 &rmem->base, (unsigned long)rmem->size / SZ_1M); 331 return ret; 332 } 333 } 334 mem->use_dev_dma_pfn_offset = true; 335 rmem->priv = mem; 336 dma_assign_coherent_memory(dev, mem); 337 return 0; 338 } 339 340 static void rmem_dma_device_release(struct reserved_mem *rmem, 341 struct device *dev) 342 { 343 if (dev) 344 dev->dma_mem = NULL; 345 } 346 347 static const struct reserved_mem_ops rmem_dma_ops = { 348 .device_init = rmem_dma_device_init, 349 .device_release = rmem_dma_device_release, 350 }; 351 352 static int __init rmem_dma_setup(struct reserved_mem *rmem) 353 { 354 unsigned long node = rmem->fdt_node; 355 356 if (of_get_flat_dt_prop(node, "reusable", NULL)) 357 return -EINVAL; 358 359 #ifdef CONFIG_ARM 360 if (!of_get_flat_dt_prop(node, "no-map", NULL)) { 361 pr_err("Reserved memory: regions without no-map are not yet supported\n"); 362 return -EINVAL; 363 } 364 365 if (of_get_flat_dt_prop(node, "linux,dma-default", NULL)) { 366 WARN(dma_reserved_default_memory, 367 "Reserved memory: region for default DMA coherent area is redefined\n"); 368 dma_reserved_default_memory = rmem; 369 } 370 #endif 371 372 rmem->ops = &rmem_dma_ops; 373 pr_info("Reserved memory: created DMA memory pool at %pa, size %ld MiB\n", 374 &rmem->base, (unsigned long)rmem->size / SZ_1M); 375 return 0; 376 } 377 378 static int __init dma_init_reserved_memory(void) 379 { 380 const struct reserved_mem_ops *ops; 381 int ret; 382 383 if (!dma_reserved_default_memory) 384 return -ENOMEM; 385 386 ops = dma_reserved_default_memory->ops; 387 388 /* 389 * We rely on rmem_dma_device_init() does not propagate error of 390 * dma_assign_coherent_memory() for "NULL" device. 391 */ 392 ret = ops->device_init(dma_reserved_default_memory, NULL); 393 394 if (!ret) { 395 dma_coherent_default_memory = dma_reserved_default_memory->priv; 396 pr_info("DMA: default coherent area is set\n"); 397 } 398 399 return ret; 400 } 401 402 core_initcall(dma_init_reserved_memory); 403 404 RESERVEDMEM_OF_DECLARE(dma, "shared-dma-pool", rmem_dma_setup); 405 #endif 406