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