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 #include <asm/dma.h> 37 38 #include "mmu_decl.h" 39 40 /* 41 * This address range defaults to a value that is safe for all 42 * platforms which currently set CONFIG_NOT_COHERENT_CACHE. It 43 * can be further configured for specific applications under 44 * the "Advanced Setup" menu. -Matt 45 */ 46 #define CONSISTENT_BASE (IOREMAP_TOP) 47 #define CONSISTENT_END (CONSISTENT_BASE + CONFIG_CONSISTENT_SIZE) 48 #define CONSISTENT_OFFSET(x) (((unsigned long)(x) - CONSISTENT_BASE) >> PAGE_SHIFT) 49 50 /* 51 * This is the page table (2MB) covering uncached, DMA consistent allocations 52 */ 53 static DEFINE_SPINLOCK(consistent_lock); 54 55 /* 56 * VM region handling support. 57 * 58 * This should become something generic, handling VM region allocations for 59 * vmalloc and similar (ioremap, module space, etc). 60 * 61 * I envisage vmalloc()'s supporting vm_struct becoming: 62 * 63 * struct vm_struct { 64 * struct vm_region region; 65 * unsigned long flags; 66 * struct page **pages; 67 * unsigned int nr_pages; 68 * unsigned long phys_addr; 69 * }; 70 * 71 * get_vm_area() would then call vm_region_alloc with an appropriate 72 * struct vm_region head (eg): 73 * 74 * struct vm_region vmalloc_head = { 75 * .vm_list = LIST_HEAD_INIT(vmalloc_head.vm_list), 76 * .vm_start = VMALLOC_START, 77 * .vm_end = VMALLOC_END, 78 * }; 79 * 80 * However, vmalloc_head.vm_start is variable (typically, it is dependent on 81 * the amount of RAM found at boot time.) I would imagine that get_vm_area() 82 * would have to initialise this each time prior to calling vm_region_alloc(). 83 */ 84 struct ppc_vm_region { 85 struct list_head vm_list; 86 unsigned long vm_start; 87 unsigned long vm_end; 88 }; 89 90 static struct ppc_vm_region consistent_head = { 91 .vm_list = LIST_HEAD_INIT(consistent_head.vm_list), 92 .vm_start = CONSISTENT_BASE, 93 .vm_end = CONSISTENT_END, 94 }; 95 96 static struct ppc_vm_region * 97 ppc_vm_region_alloc(struct ppc_vm_region *head, size_t size, gfp_t gfp) 98 { 99 unsigned long addr = head->vm_start, end = head->vm_end - size; 100 unsigned long flags; 101 struct ppc_vm_region *c, *new; 102 103 new = kmalloc(sizeof(struct ppc_vm_region), gfp); 104 if (!new) 105 goto out; 106 107 spin_lock_irqsave(&consistent_lock, flags); 108 109 list_for_each_entry(c, &head->vm_list, vm_list) { 110 if ((addr + size) < addr) 111 goto nospc; 112 if ((addr + size) <= c->vm_start) 113 goto found; 114 addr = c->vm_end; 115 if (addr > end) 116 goto nospc; 117 } 118 119 found: 120 /* 121 * Insert this entry _before_ the one we found. 122 */ 123 list_add_tail(&new->vm_list, &c->vm_list); 124 new->vm_start = addr; 125 new->vm_end = addr + size; 126 127 spin_unlock_irqrestore(&consistent_lock, flags); 128 return new; 129 130 nospc: 131 spin_unlock_irqrestore(&consistent_lock, flags); 132 kfree(new); 133 out: 134 return NULL; 135 } 136 137 static struct ppc_vm_region *ppc_vm_region_find(struct ppc_vm_region *head, unsigned long addr) 138 { 139 struct ppc_vm_region *c; 140 141 list_for_each_entry(c, &head->vm_list, vm_list) { 142 if (c->vm_start == addr) 143 goto out; 144 } 145 c = NULL; 146 out: 147 return c; 148 } 149 150 /* 151 * Allocate DMA-coherent memory space and return both the kernel remapped 152 * virtual and bus address for that space. 153 */ 154 void * 155 __dma_alloc_coherent(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp) 156 { 157 struct page *page; 158 struct ppc_vm_region *c; 159 unsigned long order; 160 u64 mask = ISA_DMA_THRESHOLD, limit; 161 162 if (dev) { 163 mask = dev->coherent_dma_mask; 164 165 /* 166 * Sanity check the DMA mask - it must be non-zero, and 167 * must be able to be satisfied by a DMA allocation. 168 */ 169 if (mask == 0) { 170 dev_warn(dev, "coherent DMA mask is unset\n"); 171 goto no_page; 172 } 173 174 if ((~mask) & ISA_DMA_THRESHOLD) { 175 dev_warn(dev, "coherent DMA mask %#llx is smaller " 176 "than system GFP_DMA mask %#llx\n", 177 mask, (unsigned long long)ISA_DMA_THRESHOLD); 178 goto no_page; 179 } 180 } 181 182 183 size = PAGE_ALIGN(size); 184 limit = (mask + 1) & ~mask; 185 if ((limit && size >= limit) || 186 size >= (CONSISTENT_END - CONSISTENT_BASE)) { 187 printk(KERN_WARNING "coherent allocation too big (requested %#x mask %#Lx)\n", 188 size, mask); 189 return NULL; 190 } 191 192 order = get_order(size); 193 194 /* Might be useful if we ever have a real legacy DMA zone... */ 195 if (mask != 0xffffffff) 196 gfp |= GFP_DMA; 197 198 page = alloc_pages(gfp, order); 199 if (!page) 200 goto no_page; 201 202 /* 203 * Invalidate any data that might be lurking in the 204 * kernel direct-mapped region for device DMA. 205 */ 206 { 207 unsigned long kaddr = (unsigned long)page_address(page); 208 memset(page_address(page), 0, size); 209 flush_dcache_range(kaddr, kaddr + size); 210 } 211 212 /* 213 * Allocate a virtual address in the consistent mapping region. 214 */ 215 c = ppc_vm_region_alloc(&consistent_head, size, 216 gfp & ~(__GFP_DMA | __GFP_HIGHMEM)); 217 if (c) { 218 unsigned long vaddr = c->vm_start; 219 struct page *end = page + (1 << order); 220 221 split_page(page, order); 222 223 /* 224 * Set the "dma handle" 225 */ 226 *handle = page_to_phys(page); 227 228 do { 229 SetPageReserved(page); 230 map_page(vaddr, page_to_phys(page), 231 pgprot_val(pgprot_noncached(PAGE_KERNEL))); 232 page++; 233 vaddr += PAGE_SIZE; 234 } while (size -= PAGE_SIZE); 235 236 /* 237 * Free the otherwise unused pages. 238 */ 239 while (page < end) { 240 __free_page(page); 241 page++; 242 } 243 244 return (void *)c->vm_start; 245 } 246 247 if (page) 248 __free_pages(page, order); 249 no_page: 250 return NULL; 251 } 252 EXPORT_SYMBOL(__dma_alloc_coherent); 253 254 /* 255 * free a page as defined by the above mapping. 256 */ 257 void __dma_free_coherent(size_t size, void *vaddr) 258 { 259 struct ppc_vm_region *c; 260 unsigned long flags, addr; 261 262 size = PAGE_ALIGN(size); 263 264 spin_lock_irqsave(&consistent_lock, flags); 265 266 c = ppc_vm_region_find(&consistent_head, (unsigned long)vaddr); 267 if (!c) 268 goto no_area; 269 270 if ((c->vm_end - c->vm_start) != size) { 271 printk(KERN_ERR "%s: freeing wrong coherent size (%ld != %d)\n", 272 __func__, c->vm_end - c->vm_start, size); 273 dump_stack(); 274 size = c->vm_end - c->vm_start; 275 } 276 277 addr = c->vm_start; 278 do { 279 pte_t *ptep; 280 unsigned long pfn; 281 282 ptep = pte_offset_kernel(pmd_offset(pud_offset(pgd_offset_k(addr), 283 addr), 284 addr), 285 addr); 286 if (!pte_none(*ptep) && pte_present(*ptep)) { 287 pfn = pte_pfn(*ptep); 288 pte_clear(&init_mm, addr, ptep); 289 if (pfn_valid(pfn)) { 290 struct page *page = pfn_to_page(pfn); 291 __free_reserved_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 | end) & (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) + seg_offset; 368 369 /* Sync this buffer segment */ 370 __dma_sync((void *)start, seg_size, direction); 371 kunmap_atomic((void *)start); 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); 401 402 /* 403 * Return the PFN for a given cpu virtual address returned by 404 * __dma_alloc_coherent. This is used by dma_mmap_coherent() 405 */ 406 unsigned long __dma_get_coherent_pfn(unsigned long cpu_addr) 407 { 408 /* This should always be populated, so we don't test every 409 * level. If that fails, we'll have a nice crash which 410 * will be as good as a BUG_ON() 411 */ 412 pgd_t *pgd = pgd_offset_k(cpu_addr); 413 pud_t *pud = pud_offset(pgd, cpu_addr); 414 pmd_t *pmd = pmd_offset(pud, cpu_addr); 415 pte_t *ptep = pte_offset_kernel(pmd, cpu_addr); 416 417 if (pte_none(*ptep) || !pte_present(*ptep)) 418 return 0; 419 return pte_pfn(*ptep); 420 } 421