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