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 static void *__dma_alloc_from_coherent(struct device *dev, 134 struct dma_coherent_mem *mem, 135 ssize_t size, dma_addr_t *dma_handle) 136 { 137 int order = get_order(size); 138 unsigned long flags; 139 int pageno; 140 void *ret; 141 142 spin_lock_irqsave(&mem->spinlock, flags); 143 144 if (unlikely(size > ((dma_addr_t)mem->size << PAGE_SHIFT))) 145 goto err; 146 147 pageno = bitmap_find_free_region(mem->bitmap, mem->size, order); 148 if (unlikely(pageno < 0)) 149 goto err; 150 151 /* 152 * Memory was found in the coherent area. 153 */ 154 *dma_handle = dma_get_device_base(dev, mem) + 155 ((dma_addr_t)pageno << PAGE_SHIFT); 156 ret = mem->virt_base + ((dma_addr_t)pageno << PAGE_SHIFT); 157 spin_unlock_irqrestore(&mem->spinlock, flags); 158 memset(ret, 0, size); 159 return ret; 160 err: 161 spin_unlock_irqrestore(&mem->spinlock, flags); 162 return NULL; 163 } 164 165 /** 166 * dma_alloc_from_dev_coherent() - allocate memory from device coherent pool 167 * @dev: device from which we allocate memory 168 * @size: size of requested memory area 169 * @dma_handle: This will be filled with the correct dma handle 170 * @ret: This pointer will be filled with the virtual address 171 * to allocated area. 172 * 173 * This function should be only called from per-arch dma_alloc_coherent() 174 * to support allocation from per-device coherent memory pools. 175 * 176 * Returns 0 if dma_alloc_coherent should continue with allocating from 177 * generic memory areas, or !0 if dma_alloc_coherent should return @ret. 178 */ 179 int dma_alloc_from_dev_coherent(struct device *dev, ssize_t size, 180 dma_addr_t *dma_handle, void **ret) 181 { 182 struct dma_coherent_mem *mem = dev_get_coherent_memory(dev); 183 184 if (!mem) 185 return 0; 186 187 *ret = __dma_alloc_from_coherent(dev, mem, size, dma_handle); 188 return 1; 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 + ((dma_addr_t)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 static int __dma_mmap_from_coherent(struct dma_coherent_mem *mem, 227 struct vm_area_struct *vma, void *vaddr, size_t size, int *ret) 228 { 229 if (mem && vaddr >= mem->virt_base && vaddr + size <= 230 (mem->virt_base + ((dma_addr_t)mem->size << PAGE_SHIFT))) { 231 unsigned long off = vma->vm_pgoff; 232 int start = (vaddr - mem->virt_base) >> PAGE_SHIFT; 233 unsigned long user_count = vma_pages(vma); 234 int count = PAGE_ALIGN(size) >> PAGE_SHIFT; 235 236 *ret = -ENXIO; 237 if (off < count && user_count <= count - off) { 238 unsigned long pfn = mem->pfn_base + start + off; 239 *ret = remap_pfn_range(vma, vma->vm_start, pfn, 240 user_count << PAGE_SHIFT, 241 vma->vm_page_prot); 242 } 243 return 1; 244 } 245 return 0; 246 } 247 248 /** 249 * dma_mmap_from_dev_coherent() - mmap memory from the device coherent pool 250 * @dev: device from which the memory was allocated 251 * @vma: vm_area for the userspace memory 252 * @vaddr: cpu address returned by dma_alloc_from_dev_coherent 253 * @size: size of the memory buffer allocated 254 * @ret: result from remap_pfn_range() 255 * 256 * This checks whether the memory was allocated from the per-device 257 * coherent memory pool and if so, maps that memory to the provided vma. 258 * 259 * Returns 1 if @vaddr belongs to the device coherent pool and the caller 260 * should return @ret, or 0 if they should proceed with mapping memory from 261 * generic areas. 262 */ 263 int dma_mmap_from_dev_coherent(struct device *dev, struct vm_area_struct *vma, 264 void *vaddr, size_t size, int *ret) 265 { 266 struct dma_coherent_mem *mem = dev_get_coherent_memory(dev); 267 268 return __dma_mmap_from_coherent(mem, vma, vaddr, size, ret); 269 } 270 271 #ifdef CONFIG_DMA_GLOBAL_POOL 272 static struct dma_coherent_mem *dma_coherent_default_memory __ro_after_init; 273 274 void *dma_alloc_from_global_coherent(struct device *dev, ssize_t size, 275 dma_addr_t *dma_handle) 276 { 277 if (!dma_coherent_default_memory) 278 return NULL; 279 280 return __dma_alloc_from_coherent(dev, dma_coherent_default_memory, size, 281 dma_handle); 282 } 283 284 int dma_release_from_global_coherent(int order, void *vaddr) 285 { 286 if (!dma_coherent_default_memory) 287 return 0; 288 289 return __dma_release_from_coherent(dma_coherent_default_memory, order, 290 vaddr); 291 } 292 293 int dma_mmap_from_global_coherent(struct vm_area_struct *vma, void *vaddr, 294 size_t size, int *ret) 295 { 296 if (!dma_coherent_default_memory) 297 return 0; 298 299 return __dma_mmap_from_coherent(dma_coherent_default_memory, vma, 300 vaddr, size, ret); 301 } 302 303 int dma_init_global_coherent(phys_addr_t phys_addr, size_t size) 304 { 305 struct dma_coherent_mem *mem; 306 307 mem = dma_init_coherent_memory(phys_addr, phys_addr, size, true); 308 if (IS_ERR(mem)) 309 return PTR_ERR(mem); 310 dma_coherent_default_memory = mem; 311 pr_info("DMA: default coherent area is set\n"); 312 return 0; 313 } 314 #endif /* CONFIG_DMA_GLOBAL_POOL */ 315 316 /* 317 * Support for reserved memory regions defined in device tree 318 */ 319 #ifdef CONFIG_OF_RESERVED_MEM 320 #include <linux/of.h> 321 #include <linux/of_fdt.h> 322 #include <linux/of_reserved_mem.h> 323 324 #ifdef CONFIG_DMA_GLOBAL_POOL 325 static struct reserved_mem *dma_reserved_default_memory __initdata; 326 #endif 327 328 static int rmem_dma_device_init(struct reserved_mem *rmem, struct device *dev) 329 { 330 if (!rmem->priv) { 331 struct dma_coherent_mem *mem; 332 333 mem = dma_init_coherent_memory(rmem->base, rmem->base, 334 rmem->size, true); 335 if (IS_ERR(mem)) 336 return PTR_ERR(mem); 337 rmem->priv = mem; 338 } 339 dma_assign_coherent_memory(dev, rmem->priv); 340 return 0; 341 } 342 343 static void rmem_dma_device_release(struct reserved_mem *rmem, 344 struct device *dev) 345 { 346 if (dev) 347 dev->dma_mem = NULL; 348 } 349 350 static const struct reserved_mem_ops rmem_dma_ops = { 351 .device_init = rmem_dma_device_init, 352 .device_release = rmem_dma_device_release, 353 }; 354 355 static int __init rmem_dma_setup(struct reserved_mem *rmem) 356 { 357 unsigned long node = rmem->fdt_node; 358 359 if (of_get_flat_dt_prop(node, "reusable", NULL)) 360 return -EINVAL; 361 362 #ifdef CONFIG_ARM 363 if (!of_get_flat_dt_prop(node, "no-map", NULL)) { 364 pr_err("Reserved memory: regions without no-map are not yet supported\n"); 365 return -EINVAL; 366 } 367 #endif 368 369 #ifdef CONFIG_DMA_GLOBAL_POOL 370 if (of_get_flat_dt_prop(node, "linux,dma-default", NULL)) { 371 WARN(dma_reserved_default_memory, 372 "Reserved memory: region for default DMA coherent area is redefined\n"); 373 dma_reserved_default_memory = rmem; 374 } 375 #endif 376 377 rmem->ops = &rmem_dma_ops; 378 pr_info("Reserved memory: created DMA memory pool at %pa, size %ld MiB\n", 379 &rmem->base, (unsigned long)rmem->size / SZ_1M); 380 return 0; 381 } 382 383 #ifdef CONFIG_DMA_GLOBAL_POOL 384 static int __init dma_init_reserved_memory(void) 385 { 386 if (!dma_reserved_default_memory) 387 return -ENOMEM; 388 return dma_init_global_coherent(dma_reserved_default_memory->base, 389 dma_reserved_default_memory->size); 390 } 391 core_initcall(dma_init_reserved_memory); 392 #endif /* CONFIG_DMA_GLOBAL_POOL */ 393 394 RESERVEDMEM_OF_DECLARE(dma, "shared-dma-pool", rmem_dma_setup); 395 #endif 396