arch/mips/mm/dma-noncoherent.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2000  Ani Joshi <ajoshi@unixbox.com>
   4  * Copyright (C) 2000, 2001, 06  Ralf Baechle <ralf@linux-mips.org>
   5  * swiped from i386, and cloned for MIPS by Geert, polished by Ralf.
   6  */
   7 #include <linux/dma-direct.h>
   8 #include <linux/dma-map-ops.h>
   9 #include <linux/highmem.h>
  10
  11 #include <asm/cache.h>
  12 #include <asm/cpu-type.h>
  13 #include <asm/io.h>
  14
  15 /*
  16  * The affected CPUs below in 'cpu_needs_post_dma_flush()' can speculatively
  17  * fill random cachelines with stale data at any time, requiring an extra
  18  * flush post-DMA.
  19  *
  20  * Warning on the terminology - Linux calls an uncached area coherent;  MIPS
  21  * terminology calls memory areas with hardware maintained coherency coherent.
  22  *
  23  * Note that the R14000 and R16000 should also be checked for in this condition.
  24  * However this function is only called on non-I/O-coherent systems and only the
  25  * R10000 and R12000 are used in such systems, the SGI IP28 Indigo² rsp.
  26  * SGI IP32 aka O2.
  27  */
  28 static inline bool cpu_needs_post_dma_flush(void)
  29 {
  30         switch (boot_cpu_type()) {
  31         case CPU_R10000:
  32         case CPU_R12000:
  33         case CPU_BMIPS5000:
  34         case CPU_LOONGSON2EF:
  35         case CPU_XBURST:
  36                 return true;
  37         default:
  38                 /*
  39                  * Presence of MAARs suggests that the CPU supports
  40                  * speculatively prefetching data, and therefore requires
  41                  * the post-DMA flush/invalidate.
  42                  */
  43                 return cpu_has_maar;
  44         }
  45 }
  46
  47 void arch_dma_prep_coherent(struct page *page, size_t size)
  48 {
  49         dma_cache_wback_inv((unsigned long)page_address(page), size);
  50 }
  51
  52 void *arch_dma_set_uncached(void *addr, size_t size)
  53 {
  54         return (void *)(__pa(addr) + UNCAC_BASE);
  55 }
  56
  57 static inline void dma_sync_virt_for_device(void *addr, size_t size,
  58                 enum dma_data_direction dir)
  59 {
  60         switch (dir) {
  61         case DMA_TO_DEVICE:
  62                 dma_cache_wback((unsigned long)addr, size);
  63                 break;
  64         case DMA_FROM_DEVICE:
  65                 dma_cache_inv((unsigned long)addr, size);
  66                 break;
  67         case DMA_BIDIRECTIONAL:
  68                 dma_cache_wback_inv((unsigned long)addr, size);
  69                 break;
  70         default:
  71                 BUG();
  72         }
  73 }
  74
  75 static inline void dma_sync_virt_for_cpu(void *addr, size_t size,
  76                 enum dma_data_direction dir)
  77 {
  78         switch (dir) {
  79         case DMA_TO_DEVICE:
  80                 break;
  81         case DMA_FROM_DEVICE:
  82         case DMA_BIDIRECTIONAL:
  83                 dma_cache_inv((unsigned long)addr, size);
  84                 break;
  85         default:
  86                 BUG();
  87         }
  88 }
  89
  90 /*
  91  * A single sg entry may refer to multiple physically contiguous pages.  But
  92  * we still need to process highmem pages individually.  If highmem is not
  93  * configured then the bulk of this loop gets optimized out.
  94  */
  95 static inline void dma_sync_phys(phys_addr_t paddr, size_t size,
  96                 enum dma_data_direction dir, bool for_device)
  97 {
  98         struct page *page = pfn_to_page(paddr >> PAGE_SHIFT);
  99         unsigned long offset = paddr & ~PAGE_MASK;
 100         size_t left = size;
 101
 102         do {
 103                 size_t len = left;
 104                 void *addr;
 105
 106                 if (PageHighMem(page)) {
 107                         if (offset + len > PAGE_SIZE)
 108                                 len = PAGE_SIZE - offset;
 109                 }
 110
 111                 addr = kmap_atomic(page);
 112                 if (for_device)
 113                         dma_sync_virt_for_device(addr + offset, len, dir);
 114                 else
 115                         dma_sync_virt_for_cpu(addr + offset, len, dir);
 116                 kunmap_atomic(addr);
 117
 118                 offset = 0;
 119                 page++;
 120                 left -= len;
 121         } while (left);
 122 }
 123
 124 void arch_sync_dma_for_device(phys_addr_t paddr, size_t size,
 125                 enum dma_data_direction dir)
 126 {
 127         dma_sync_phys(paddr, size, dir, true);
 128 }
 129
 130 #ifdef CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU
 131 void arch_sync_dma_for_cpu(phys_addr_t paddr, size_t size,
 132                 enum dma_data_direction dir)
 133 {
 134         if (cpu_needs_post_dma_flush())
 135                 dma_sync_phys(paddr, size, dir, false);
 136 }
 137 #endif
 138
 139 #ifdef CONFIG_ARCH_HAS_SETUP_DMA_OPS
 140 void arch_setup_dma_ops(struct device *dev, bool coherent)
 141 {
 142         dev->dma_coherent = coherent;
 143 }
 144 #endif