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