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/slab.h> 27 #include <linux/kernel.h> 28 #include <linux/errno.h> 29 #include <linux/string.h> 30 #include <linux/types.h> 31 #include <linux/highmem.h> 32 #include <linux/dma-mapping.h> 33 34 #include <asm/tlbflush.h> 35 36 #include "mmu_decl.h" 37 38 /* 39 * This address range defaults to a value that is safe for all 40 * platforms which currently set CONFIG_NOT_COHERENT_CACHE. It 41 * can be further configured for specific applications under 42 * the "Advanced Setup" menu. -Matt 43 */ 44 #define CONSISTENT_BASE (IOREMAP_TOP) 45 #define CONSISTENT_END (CONSISTENT_BASE + CONFIG_CONSISTENT_SIZE) 46 #define CONSISTENT_OFFSET(x) (((unsigned long)(x) - CONSISTENT_BASE) >> PAGE_SHIFT) 47 48 /* 49 * This is the page table (2MB) covering uncached, DMA consistent allocations 50 */ 51 static DEFINE_SPINLOCK(consistent_lock); 52 53 /* 54 * VM region handling support. 55 * 56 * This should become something generic, handling VM region allocations for 57 * vmalloc and similar (ioremap, module space, etc). 58 * 59 * I envisage vmalloc()'s supporting vm_struct becoming: 60 * 61 * struct vm_struct { 62 * struct vm_region region; 63 * unsigned long flags; 64 * struct page **pages; 65 * unsigned int nr_pages; 66 * unsigned long phys_addr; 67 * }; 68 * 69 * get_vm_area() would then call vm_region_alloc with an appropriate 70 * struct vm_region head (eg): 71 * 72 * struct vm_region vmalloc_head = { 73 * .vm_list = LIST_HEAD_INIT(vmalloc_head.vm_list), 74 * .vm_start = VMALLOC_START, 75 * .vm_end = VMALLOC_END, 76 * }; 77 * 78 * However, vmalloc_head.vm_start is variable (typically, it is dependent on 79 * the amount of RAM found at boot time.) I would imagine that get_vm_area() 80 * would have to initialise this each time prior to calling vm_region_alloc(). 81 */ 82 struct ppc_vm_region { 83 struct list_head vm_list; 84 unsigned long vm_start; 85 unsigned long vm_end; 86 }; 87 88 static struct ppc_vm_region consistent_head = { 89 .vm_list = LIST_HEAD_INIT(consistent_head.vm_list), 90 .vm_start = CONSISTENT_BASE, 91 .vm_end = CONSISTENT_END, 92 }; 93 94 static struct ppc_vm_region * 95 ppc_vm_region_alloc(struct ppc_vm_region *head, size_t size, gfp_t gfp) 96 { 97 unsigned long addr = head->vm_start, end = head->vm_end - size; 98 unsigned long flags; 99 struct ppc_vm_region *c, *new; 100 101 new = kmalloc(sizeof(struct ppc_vm_region), gfp); 102 if (!new) 103 goto out; 104 105 spin_lock_irqsave(&consistent_lock, flags); 106 107 list_for_each_entry(c, &head->vm_list, vm_list) { 108 if ((addr + size) < addr) 109 goto nospc; 110 if ((addr + size) <= c->vm_start) 111 goto found; 112 addr = c->vm_end; 113 if (addr > end) 114 goto nospc; 115 } 116 117 found: 118 /* 119 * Insert this entry _before_ the one we found. 120 */ 121 list_add_tail(&new->vm_list, &c->vm_list); 122 new->vm_start = addr; 123 new->vm_end = addr + size; 124 125 spin_unlock_irqrestore(&consistent_lock, flags); 126 return new; 127 128 nospc: 129 spin_unlock_irqrestore(&consistent_lock, flags); 130 kfree(new); 131 out: 132 return NULL; 133 } 134 135 static struct ppc_vm_region *ppc_vm_region_find(struct ppc_vm_region *head, unsigned long addr) 136 { 137 struct ppc_vm_region *c; 138 139 list_for_each_entry(c, &head->vm_list, vm_list) { 140 if (c->vm_start == addr) 141 goto out; 142 } 143 c = NULL; 144 out: 145 return c; 146 } 147 148 /* 149 * Allocate DMA-coherent memory space and return both the kernel remapped 150 * virtual and bus address for that space. 151 */ 152 void * 153 __dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp) 154 { 155 struct page *page; 156 struct ppc_vm_region *c; 157 unsigned long order; 158 u64 mask = ISA_DMA_THRESHOLD, limit; 159 160 if (dev) { 161 mask = dev->coherent_dma_mask; 162 163 /* 164 * Sanity check the DMA mask - it must be non-zero, and 165 * must be able to be satisfied by a DMA allocation. 166 */ 167 if (mask == 0) { 168 dev_warn(dev, "coherent DMA mask is unset\n"); 169 goto no_page; 170 } 171 172 if ((~mask) & ISA_DMA_THRESHOLD) { 173 dev_warn(dev, "coherent DMA mask %#llx is smaller " 174 "than system GFP_DMA mask %#llx\n", 175 mask, (unsigned long long)ISA_DMA_THRESHOLD); 176 goto no_page; 177 } 178 } 179 180 181 size = PAGE_ALIGN(size); 182 limit = (mask + 1) & ~mask; 183 if ((limit && size >= limit) || 184 size >= (CONSISTENT_END - CONSISTENT_BASE)) { 185 printk(KERN_WARNING "coherent allocation too big (requested %#x mask %#Lx)\n", 186 size, mask); 187 return NULL; 188 } 189 190 order = get_order(size); 191 192 /* Might be useful if we ever have a real legacy DMA zone... */ 193 if (mask != 0xffffffff) 194 gfp |= GFP_DMA; 195 196 page = alloc_pages(gfp, order); 197 if (!page) 198 goto no_page; 199 200 /* 201 * Invalidate any data that might be lurking in the 202 * kernel direct-mapped region for device DMA. 203 */ 204 { 205 unsigned long kaddr = (unsigned long)page_address(page); 206 memset(page_address(page), 0, size); 207 flush_dcache_range(kaddr, kaddr + size); 208 } 209 210 /* 211 * Allocate a virtual address in the consistent mapping region. 212 */ 213 c = ppc_vm_region_alloc(&consistent_head, size, 214 gfp & ~(__GFP_DMA | __GFP_HIGHMEM)); 215 if (c) { 216 unsigned long vaddr = c->vm_start; 217 struct page *end = page + (1 << order); 218 219 split_page(page, order); 220 221 /* 222 * Set the "dma handle" 223 */ 224 *handle = page_to_phys(page); 225 226 do { 227 SetPageReserved(page); 228 map_page(vaddr, page_to_phys(page), 229 pgprot_noncached(PAGE_KERNEL)); 230 page++; 231 vaddr += PAGE_SIZE; 232 } while (size -= PAGE_SIZE); 233 234 /* 235 * Free the otherwise unused pages. 236 */ 237 while (page < end) { 238 __free_page(page); 239 page++; 240 } 241 242 return (void *)c->vm_start; 243 } 244 245 if (page) 246 __free_pages(page, order); 247 no_page: 248 return NULL; 249 } 250 EXPORT_SYMBOL(__dma_alloc_coherent); 251 252 /* 253 * free a page as defined by the above mapping. 254 */ 255 void __dma_free_coherent(size_t size, void *vaddr) 256 { 257 struct ppc_vm_region *c; 258 unsigned long flags, addr; 259 260 size = PAGE_ALIGN(size); 261 262 spin_lock_irqsave(&consistent_lock, flags); 263 264 c = ppc_vm_region_find(&consistent_head, (unsigned long)vaddr); 265 if (!c) 266 goto no_area; 267 268 if ((c->vm_end - c->vm_start) != size) { 269 printk(KERN_ERR "%s: freeing wrong coherent size (%ld != %d)\n", 270 __func__, c->vm_end - c->vm_start, size); 271 dump_stack(); 272 size = c->vm_end - c->vm_start; 273 } 274 275 addr = c->vm_start; 276 do { 277 pte_t *ptep; 278 unsigned long pfn; 279 280 ptep = pte_offset_kernel(pmd_offset(pud_offset(pgd_offset_k(addr), 281 addr), 282 addr), 283 addr); 284 if (!pte_none(*ptep) && pte_present(*ptep)) { 285 pfn = pte_pfn(*ptep); 286 pte_clear(&init_mm, addr, ptep); 287 if (pfn_valid(pfn)) { 288 struct page *page = pfn_to_page(pfn); 289 290 ClearPageReserved(page); 291 __free_page(page); 292 } 293 } 294 addr += PAGE_SIZE; 295 } while (size -= PAGE_SIZE); 296 297 flush_tlb_kernel_range(c->vm_start, c->vm_end); 298 299 list_del(&c->vm_list); 300 301 spin_unlock_irqrestore(&consistent_lock, flags); 302 303 kfree(c); 304 return; 305 306 no_area: 307 spin_unlock_irqrestore(&consistent_lock, flags); 308 printk(KERN_ERR "%s: trying to free invalid coherent area: %p\n", 309 __func__, vaddr); 310 dump_stack(); 311 } 312 EXPORT_SYMBOL(__dma_free_coherent); 313 314 /* 315 * make an area consistent. 316 */ 317 void __dma_sync(void *vaddr, size_t size, int direction) 318 { 319 unsigned long start = (unsigned long)vaddr; 320 unsigned long end = start + size; 321 322 switch (direction) { 323 case DMA_NONE: 324 BUG(); 325 case DMA_FROM_DEVICE: 326 /* 327 * invalidate only when cache-line aligned otherwise there is 328 * the potential for discarding uncommitted data from the cache 329 */ 330 if ((start & (L1_CACHE_BYTES - 1)) || (size & (L1_CACHE_BYTES - 1))) 331 flush_dcache_range(start, end); 332 else 333 invalidate_dcache_range(start, end); 334 break; 335 case DMA_TO_DEVICE: /* writeback only */ 336 clean_dcache_range(start, end); 337 break; 338 case DMA_BIDIRECTIONAL: /* writeback and invalidate */ 339 flush_dcache_range(start, end); 340 break; 341 } 342 } 343 EXPORT_SYMBOL(__dma_sync); 344 345 #ifdef CONFIG_HIGHMEM 346 /* 347 * __dma_sync_page() implementation for systems using highmem. 348 * In this case, each page of a buffer must be kmapped/kunmapped 349 * in order to have a virtual address for __dma_sync(). This must 350 * not sleep so kmap_atomic()/kunmap_atomic() are used. 351 * 352 * Note: yes, it is possible and correct to have a buffer extend 353 * beyond the first page. 354 */ 355 static inline void __dma_sync_page_highmem(struct page *page, 356 unsigned long offset, size_t size, int direction) 357 { 358 size_t seg_size = min((size_t)(PAGE_SIZE - offset), size); 359 size_t cur_size = seg_size; 360 unsigned long flags, start, seg_offset = offset; 361 int nr_segs = 1 + ((size - seg_size) + PAGE_SIZE - 1)/PAGE_SIZE; 362 int seg_nr = 0; 363 364 local_irq_save(flags); 365 366 do { 367 start = (unsigned long)kmap_atomic(page + seg_nr, 368 KM_PPC_SYNC_PAGE) + seg_offset; 369 370 /* Sync this buffer segment */ 371 __dma_sync((void *)start, seg_size, direction); 372 kunmap_atomic((void *)start, KM_PPC_SYNC_PAGE); 373 seg_nr++; 374 375 /* Calculate next buffer segment size */ 376 seg_size = min((size_t)PAGE_SIZE, size - cur_size); 377 378 /* Add the segment size to our running total */ 379 cur_size += seg_size; 380 seg_offset = 0; 381 } while (seg_nr < nr_segs); 382 383 local_irq_restore(flags); 384 } 385 #endif /* CONFIG_HIGHMEM */ 386 387 /* 388 * __dma_sync_page makes memory consistent. identical to __dma_sync, but 389 * takes a struct page instead of a virtual address 390 */ 391 void __dma_sync_page(struct page *page, unsigned long offset, 392 size_t size, int direction) 393 { 394 #ifdef CONFIG_HIGHMEM 395 __dma_sync_page_highmem(page, offset, size, direction); 396 #else 397 unsigned long start = (unsigned long)page_address(page) + offset; 398 __dma_sync((void *)start, size, direction); 399 #endif 400 } 401 EXPORT_SYMBOL(__dma_sync_page); 402 403 /* 404 * Return the PFN for a given cpu virtual address returned by 405 * __dma_alloc_coherent. This is used by dma_mmap_coherent() 406 */ 407 unsigned long __dma_get_coherent_pfn(unsigned long cpu_addr) 408 { 409 /* This should always be populated, so we don't test every 410 * level. If that fails, we'll have a nice crash which 411 * will be as good as a BUG_ON() 412 */ 413 pgd_t *pgd = pgd_offset_k(cpu_addr); 414 pud_t *pud = pud_offset(pgd, cpu_addr); 415 pmd_t *pmd = pmd_offset(pud, cpu_addr); 416 pte_t *ptep = pte_offset_kernel(pmd, cpu_addr); 417 418 if (pte_none(*ptep) || !pte_present(*ptep)) 419 return 0; 420 return pte_pfn(*ptep); 421 } 422