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 145