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