1 /* 2 * PowerPC version derived from arch/arm/mm/consistent.c 3 * Copyright (C) 2001 Dan Malek (dmalek@jlc.net) 4 * 5 * Copyright (C) 2000 Russell King 6 * 7 * Consistent memory allocators. Used for DMA devices that want to 8 * share uncached memory with the processor core. The function return 9 * is the virtual address and 'dma_handle' is the physical address. 10 * Mostly stolen from the ARM port, with some changes for PowerPC. 11 * -- Dan 12 * 13 * Reorganized to get rid of the arch-specific consistent_* functions 14 * and provide non-coherent implementations for the DMA API. -Matt 15 * 16 * Added in_interrupt() safe dma_alloc_coherent()/dma_free_coherent() 17 * implementation. This is pulled straight from ARM and barely 18 * modified. -Matt 19 * 20 * This program is free software; you can redistribute it and/or modify 21 * it under the terms of the GNU General Public License version 2 as 22 * published by the Free Software Foundation. 23 */ 24 25 #include <linux/sched.h> 26 #include <linux/kernel.h> 27 #include <linux/errno.h> 28 #include <linux/string.h> 29 #include <linux/types.h> 30 #include <linux/highmem.h> 31 #include <linux/dma-mapping.h> 32 33 #include <asm/tlbflush.h> 34 35 #include "mmu_decl.h" 36 37 /* 38 * This address range defaults to a value that is safe for all 39 * platforms which currently set CONFIG_NOT_COHERENT_CACHE. It 40 * can be further configured for specific applications under 41 * the "Advanced Setup" menu. -Matt 42 */ 43 #define CONSISTENT_BASE (IOREMAP_TOP) 44 #define CONSISTENT_END (CONSISTENT_BASE + CONFIG_CONSISTENT_SIZE) 45 #define CONSISTENT_OFFSET(x) (((unsigned long)(x) - CONSISTENT_BASE) >> PAGE_SHIFT) 46 47 /* 48 * This is the page table (2MB) covering uncached, DMA consistent allocations 49 */ 50 static DEFINE_SPINLOCK(consistent_lock); 51 52 /* 53 * VM region handling support. 54 * 55 * This should become something generic, handling VM region allocations for 56 * vmalloc and similar (ioremap, module space, etc). 57 * 58 * I envisage vmalloc()'s supporting vm_struct becoming: 59 * 60 * struct vm_struct { 61 * struct vm_region region; 62 * unsigned long flags; 63 * struct page **pages; 64 * unsigned int nr_pages; 65 * unsigned long phys_addr; 66 * }; 67 * 68 * get_vm_area() would then call vm_region_alloc with an appropriate 69 * struct vm_region head (eg): 70 * 71 * struct vm_region vmalloc_head = { 72 * .vm_list = LIST_HEAD_INIT(vmalloc_head.vm_list), 73 * .vm_start = VMALLOC_START, 74 * .vm_end = VMALLOC_END, 75 * }; 76 * 77 * However, vmalloc_head.vm_start is variable (typically, it is dependent on 78 * the amount of RAM found at boot time.) I would imagine that get_vm_area() 79 * would have to initialise this each time prior to calling vm_region_alloc(). 80 */ 81 struct ppc_vm_region { 82 struct list_head vm_list; 83 unsigned long vm_start; 84 unsigned long vm_end; 85 }; 86 87 static struct ppc_vm_region consistent_head = { 88 .vm_list = LIST_HEAD_INIT(consistent_head.vm_list), 89 .vm_start = CONSISTENT_BASE, 90 .vm_end = CONSISTENT_END, 91 }; 92 93 static struct ppc_vm_region * 94 ppc_vm_region_alloc(struct ppc_vm_region *head, size_t size, gfp_t gfp) 95 { 96 unsigned long addr = head->vm_start, end = head->vm_end - size; 97 unsigned long flags; 98 struct ppc_vm_region *c, *new; 99 100 new = kmalloc(sizeof(struct ppc_vm_region), gfp); 101 if (!new) 102 goto out; 103 104 spin_lock_irqsave(&consistent_lock, flags); 105 106 list_for_each_entry(c, &head->vm_list, vm_list) { 107 if ((addr + size) < addr) 108 goto nospc; 109 if ((addr + size) <= c->vm_start) 110 goto found; 111 addr = c->vm_end; 112 if (addr > end) 113 goto nospc; 114 } 115 116 found: 117 /* 118 * Insert this entry _before_ the one we found. 119 */ 120 list_add_tail(&new->vm_list, &c->vm_list); 121 new->vm_start = addr; 122 new->vm_end = addr + size; 123 124 spin_unlock_irqrestore(&consistent_lock, flags); 125 return new; 126 127 nospc: 128 spin_unlock_irqrestore(&consistent_lock, flags); 129 kfree(new); 130 out: 131 return NULL; 132 } 133 134 static struct ppc_vm_region *ppc_vm_region_find(struct ppc_vm_region *head, unsigned long addr) 135 { 136 struct ppc_vm_region *c; 137 138 list_for_each_entry(c, &head->vm_list, vm_list) { 139 if (c->vm_start == addr) 140 goto out; 141 } 142 c = NULL; 143 out: 144 return c; 145 } 146 147 /* 148 * Allocate DMA-coherent memory space and return both the kernel remapped 149 * virtual and bus address for that space. 150 */ 151 void * 152 __dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp) 153 { 154 struct page *page; 155 struct ppc_vm_region *c; 156 unsigned long order; 157 u64 mask = ISA_DMA_THRESHOLD, limit; 158 159 if (dev) { 160 mask = dev->coherent_dma_mask; 161 162 /* 163 * Sanity check the DMA mask - it must be non-zero, and 164 * must be able to be satisfied by a DMA allocation. 165 */ 166 if (mask == 0) { 167 dev_warn(dev, "coherent DMA mask is unset\n"); 168 goto no_page; 169 } 170 171 if ((~mask) & ISA_DMA_THRESHOLD) { 172 dev_warn(dev, "coherent DMA mask %#llx is smaller " 173 "than system GFP_DMA mask %#llx\n", 174 mask, (unsigned long long)ISA_DMA_THRESHOLD); 175 goto no_page; 176 } 177 } 178 179 180 size = PAGE_ALIGN(size); 181 limit = (mask + 1) & ~mask; 182 if ((limit && size >= limit) || 183 size >= (CONSISTENT_END - CONSISTENT_BASE)) { 184 printk(KERN_WARNING "coherent allocation too big (requested %#x mask %#Lx)\n", 185 size, mask); 186 return NULL; 187 } 188 189 order = get_order(size); 190 191 /* Might be useful if we ever have a real legacy DMA zone... */ 192 if (mask != 0xffffffff) 193 gfp |= GFP_DMA; 194 195 page = alloc_pages(gfp, order); 196 if (!page) 197 goto no_page; 198 199 /* 200 * Invalidate any data that might be lurking in the 201 * kernel direct-mapped region for device DMA. 202 */ 203 { 204 unsigned long kaddr = (unsigned long)page_address(page); 205 memset(page_address(page), 0, size); 206 flush_dcache_range(kaddr, kaddr + size); 207 } 208 209 /* 210 * Allocate a virtual address in the consistent mapping region. 211 */ 212 c = ppc_vm_region_alloc(&consistent_head, size, 213 gfp & ~(__GFP_DMA | __GFP_HIGHMEM)); 214 if (c) { 215 unsigned long vaddr = c->vm_start; 216 struct page *end = page + (1 << order); 217 218 split_page(page, order); 219 220 /* 221 * Set the "dma handle" 222 */ 223 *handle = page_to_phys(page); 224 225 do { 226 SetPageReserved(page); 227 map_page(vaddr, page_to_phys(page), 228 pgprot_noncached(PAGE_KERNEL)); 229 page++; 230 vaddr += PAGE_SIZE; 231 } while (size -= PAGE_SIZE); 232 233 /* 234 * Free the otherwise unused pages. 235 */ 236 while (page < end) { 237 __free_page(page); 238 page++; 239 } 240 241 return (void *)c->vm_start; 242 } 243 244 if (page) 245 __free_pages(page, order); 246 no_page: 247 return NULL; 248 } 249 EXPORT_SYMBOL(__dma_alloc_coherent); 250 251 /* 252 * free a page as defined by the above mapping. 253 */ 254 void __dma_free_coherent(size_t size, void *vaddr) 255 { 256 struct ppc_vm_region *c; 257 unsigned long flags, addr; 258 259 size = PAGE_ALIGN(size); 260 261 spin_lock_irqsave(&consistent_lock, flags); 262 263 c = ppc_vm_region_find(&consistent_head, (unsigned long)vaddr); 264 if (!c) 265 goto no_area; 266 267 if ((c->vm_end - c->vm_start) != size) { 268 printk(KERN_ERR "%s: freeing wrong coherent size (%ld != %d)\n", 269 __func__, c->vm_end - c->vm_start, size); 270 dump_stack(); 271 size = c->vm_end - c->vm_start; 272 } 273 274 addr = c->vm_start; 275 do { 276 pte_t *ptep; 277 unsigned long pfn; 278 279 ptep = pte_offset_kernel(pmd_offset(pud_offset(pgd_offset_k(addr), 280 addr), 281 addr), 282 addr); 283 if (!pte_none(*ptep) && pte_present(*ptep)) { 284 pfn = pte_pfn(*ptep); 285 pte_clear(&init_mm, addr, ptep); 286 if (pfn_valid(pfn)) { 287 struct page *page = pfn_to_page(pfn); 288 289 ClearPageReserved(page); 290 __free_page(page); 291 } 292 } 293 addr += PAGE_SIZE; 294 } while (size -= PAGE_SIZE); 295 296 flush_tlb_kernel_range(c->vm_start, c->vm_end); 297 298 list_del(&c->vm_list); 299 300 spin_unlock_irqrestore(&consistent_lock, flags); 301 302 kfree(c); 303 return; 304 305 no_area: 306 spin_unlock_irqrestore(&consistent_lock, flags); 307 printk(KERN_ERR "%s: trying to free invalid coherent area: %p\n", 308 __func__, vaddr); 309 dump_stack(); 310 } 311 EXPORT_SYMBOL(__dma_free_coherent); 312 313 /* 314 * make an area consistent. 315 */ 316 void __dma_sync(void *vaddr, size_t size, int direction) 317 { 318 unsigned long start = (unsigned long)vaddr; 319 unsigned long end = start + size; 320 321 switch (direction) { 322 case DMA_NONE: 323 BUG(); 324 case DMA_FROM_DEVICE: 325 /* 326 * invalidate only when cache-line aligned otherwise there is 327 * the potential for discarding uncommitted data from the cache 328 */ 329 if ((start & (L1_CACHE_BYTES - 1)) || (size & (L1_CACHE_BYTES - 1))) 330 flush_dcache_range(start, end); 331 else 332 invalidate_dcache_range(start, end); 333 break; 334 case DMA_TO_DEVICE: /* writeback only */ 335 clean_dcache_range(start, end); 336 break; 337 case DMA_BIDIRECTIONAL: /* writeback and invalidate */ 338 flush_dcache_range(start, end); 339 break; 340 } 341 } 342 EXPORT_SYMBOL(__dma_sync); 343 344 #ifdef CONFIG_HIGHMEM 345 /* 346 * __dma_sync_page() implementation for systems using highmem. 347 * In this case, each page of a buffer must be kmapped/kunmapped 348 * in order to have a virtual address for __dma_sync(). This must 349 * not sleep so kmap_atomic()/kunmap_atomic() are used. 350 * 351 * Note: yes, it is possible and correct to have a buffer extend 352 * beyond the first page. 353 */ 354 static inline void __dma_sync_page_highmem(struct page *page, 355 unsigned long offset, size_t size, int direction) 356 { 357 size_t seg_size = min((size_t)(PAGE_SIZE - offset), size); 358 size_t cur_size = seg_size; 359 unsigned long flags, start, seg_offset = offset; 360 int nr_segs = 1 + ((size - seg_size) + PAGE_SIZE - 1)/PAGE_SIZE; 361 int seg_nr = 0; 362 363 local_irq_save(flags); 364 365 do { 366 start = (unsigned long)kmap_atomic(page + seg_nr, 367 KM_PPC_SYNC_PAGE) + seg_offset; 368 369 /* Sync this buffer segment */ 370 __dma_sync((void *)start, seg_size, direction); 371 kunmap_atomic((void *)start, KM_PPC_SYNC_PAGE); 372 seg_nr++; 373 374 /* Calculate next buffer segment size */ 375 seg_size = min((size_t)PAGE_SIZE, size - cur_size); 376 377 /* Add the segment size to our running total */ 378 cur_size += seg_size; 379 seg_offset = 0; 380 } while (seg_nr < nr_segs); 381 382 local_irq_restore(flags); 383 } 384 #endif /* CONFIG_HIGHMEM */ 385 386 /* 387 * __dma_sync_page makes memory consistent. identical to __dma_sync, but 388 * takes a struct page instead of a virtual address 389 */ 390 void __dma_sync_page(struct page *page, unsigned long offset, 391 size_t size, int direction) 392 { 393 #ifdef CONFIG_HIGHMEM 394 __dma_sync_page_highmem(page, offset, size, direction); 395 #else 396 unsigned long start = (unsigned long)page_address(page) + offset; 397 __dma_sync((void *)start, size, direction); 398 #endif 399 } 400 EXPORT_SYMBOL(__dma_sync_page); 401