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