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