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