1# SPDX-License-Identifier: GPL-2.0-only 2 3config NO_DMA 4 bool 5 6config HAS_DMA 7 bool 8 depends on !NO_DMA 9 default y 10 11config DMA_OPS 12 depends on HAS_DMA 13 bool 14 15# 16# IOMMU drivers that can bypass the IOMMU code and optionally use the direct 17# mapping fast path should select this option and set the dma_ops_bypass 18# flag in struct device where applicable 19# 20config DMA_OPS_BYPASS 21 bool 22 23# Lets platform IOMMU driver choose between bypass and IOMMU 24config ARCH_HAS_DMA_MAP_DIRECT 25 bool 26 27config NEED_SG_DMA_FLAGS 28 bool 29 30config NEED_SG_DMA_LENGTH 31 bool 32 33config NEED_DMA_MAP_STATE 34 bool 35 36config ARCH_DMA_ADDR_T_64BIT 37 def_bool 64BIT || PHYS_ADDR_T_64BIT 38 39config ARCH_HAS_DMA_SET_MASK 40 bool 41 42# 43# Select this option if the architecture needs special handling for 44# DMA_ATTR_WRITE_COMBINE. Normally the "uncached" mapping should be what 45# people thing of when saying write combine, so very few platforms should 46# need to enable this. 47# 48config ARCH_HAS_DMA_WRITE_COMBINE 49 bool 50 51# 52# Select if the architectures provides the arch_dma_mark_clean hook 53# 54config ARCH_HAS_DMA_MARK_CLEAN 55 bool 56 57config DMA_DECLARE_COHERENT 58 bool 59 60config ARCH_HAS_SETUP_DMA_OPS 61 bool 62 63config ARCH_HAS_TEARDOWN_DMA_OPS 64 bool 65 66config ARCH_HAS_SYNC_DMA_FOR_DEVICE 67 bool 68 69config ARCH_HAS_SYNC_DMA_FOR_CPU 70 bool 71 select NEED_DMA_MAP_STATE 72 73config ARCH_HAS_SYNC_DMA_FOR_CPU_ALL 74 bool 75 76config ARCH_HAS_DMA_PREP_COHERENT 77 bool 78 79config ARCH_HAS_FORCE_DMA_UNENCRYPTED 80 bool 81 82# 83# Select this option if the architecture assumes DMA devices are coherent 84# by default. 85# 86config ARCH_DMA_DEFAULT_COHERENT 87 bool 88 89config SWIOTLB 90 bool 91 select NEED_DMA_MAP_STATE 92 93config DMA_RESTRICTED_POOL 94 bool "DMA Restricted Pool" 95 depends on OF && OF_RESERVED_MEM && SWIOTLB 96 help 97 This enables support for restricted DMA pools which provide a level of 98 DMA memory protection on systems with limited hardware protection 99 capabilities, such as those lacking an IOMMU. 100 101 For more information see 102 <Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt> 103 and <kernel/dma/swiotlb.c>. 104 If unsure, say "n". 105 106# 107# Should be selected if we can mmap non-coherent mappings to userspace. 108# The only thing that is really required is a way to set an uncached bit 109# in the pagetables 110# 111config DMA_NONCOHERENT_MMAP 112 default y if !MMU 113 bool 114 115config DMA_COHERENT_POOL 116 select GENERIC_ALLOCATOR 117 bool 118 119config DMA_GLOBAL_POOL 120 select DMA_DECLARE_COHERENT 121 bool 122 123config DMA_DIRECT_REMAP 124 bool 125 select DMA_COHERENT_POOL 126 select DMA_NONCOHERENT_MMAP 127 128config DMA_CMA 129 bool "DMA Contiguous Memory Allocator" 130 depends on HAVE_DMA_CONTIGUOUS && CMA 131 help 132 This enables the Contiguous Memory Allocator which allows drivers 133 to allocate big physically-contiguous blocks of memory for use with 134 hardware components that do not support I/O map nor scatter-gather. 135 136 You can disable CMA by specifying "cma=0" on the kernel's command 137 line. 138 139 For more information see <kernel/dma/contiguous.c>. 140 If unsure, say "n". 141 142if DMA_CMA 143 144config DMA_PERNUMA_CMA 145 bool "Enable separate DMA Contiguous Memory Area for each NUMA Node" 146 default NUMA && ARM64 147 help 148 Enable this option to get pernuma CMA areas so that devices like 149 ARM64 SMMU can get local memory by DMA coherent APIs. 150 151 You can set the size of pernuma CMA by specifying "cma_pernuma=size" 152 on the kernel's command line. 153 154comment "Default contiguous memory area size:" 155 156config CMA_SIZE_MBYTES 157 int "Size in Mega Bytes" 158 depends on !CMA_SIZE_SEL_PERCENTAGE 159 default 0 if X86 160 default 16 161 help 162 Defines the size (in MiB) of the default memory area for Contiguous 163 Memory Allocator. If the size of 0 is selected, CMA is disabled by 164 default, but it can be enabled by passing cma=size[MG] to the kernel. 165 166 167config CMA_SIZE_PERCENTAGE 168 int "Percentage of total memory" 169 depends on !CMA_SIZE_SEL_MBYTES 170 default 0 if X86 171 default 10 172 help 173 Defines the size of the default memory area for Contiguous Memory 174 Allocator as a percentage of the total memory in the system. 175 If 0 percent is selected, CMA is disabled by default, but it can be 176 enabled by passing cma=size[MG] to the kernel. 177 178choice 179 prompt "Selected region size" 180 default CMA_SIZE_SEL_MBYTES 181 182config CMA_SIZE_SEL_MBYTES 183 bool "Use mega bytes value only" 184 185config CMA_SIZE_SEL_PERCENTAGE 186 bool "Use percentage value only" 187 188config CMA_SIZE_SEL_MIN 189 bool "Use lower value (minimum)" 190 191config CMA_SIZE_SEL_MAX 192 bool "Use higher value (maximum)" 193 194endchoice 195 196config CMA_ALIGNMENT 197 int "Maximum PAGE_SIZE order of alignment for contiguous buffers" 198 range 2 12 199 default 8 200 help 201 DMA mapping framework by default aligns all buffers to the smallest 202 PAGE_SIZE order which is greater than or equal to the requested buffer 203 size. This works well for buffers up to a few hundreds kilobytes, but 204 for larger buffers it just a memory waste. With this parameter you can 205 specify the maximum PAGE_SIZE order for contiguous buffers. Larger 206 buffers will be aligned only to this specified order. The order is 207 expressed as a power of two multiplied by the PAGE_SIZE. 208 209 For example, if your system defaults to 4KiB pages, the order value 210 of 8 means that the buffers will be aligned up to 1MiB only. 211 212 If unsure, leave the default value "8". 213 214endif 215 216config DMA_API_DEBUG 217 bool "Enable debugging of DMA-API usage" 218 select NEED_DMA_MAP_STATE 219 help 220 Enable this option to debug the use of the DMA API by device drivers. 221 With this option you will be able to detect common bugs in device 222 drivers like double-freeing of DMA mappings or freeing mappings that 223 were never allocated. 224 225 This option causes a performance degradation. Use only if you want to 226 debug device drivers and dma interactions. 227 228 If unsure, say N. 229 230config DMA_API_DEBUG_SG 231 bool "Debug DMA scatter-gather usage" 232 default y 233 depends on DMA_API_DEBUG 234 help 235 Perform extra checking that callers of dma_map_sg() have respected the 236 appropriate segment length/boundary limits for the given device when 237 preparing DMA scatterlists. 238 239 This is particularly likely to have been overlooked in cases where the 240 dma_map_sg() API is used for general bulk mapping of pages rather than 241 preparing literal scatter-gather descriptors, where there is a risk of 242 unexpected behaviour from DMA API implementations if the scatterlist 243 is technically out-of-spec. 244 245 If unsure, say N. 246 247config DMA_MAP_BENCHMARK 248 bool "Enable benchmarking of streaming DMA mapping" 249 depends on DEBUG_FS 250 help 251 Provides /sys/kernel/debug/dma_map_benchmark that helps with testing 252 performance of dma_(un)map_page. 253 254 See tools/testing/selftests/dma/dma_map_benchmark.c 255