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 think 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 SWIOTLB_DYNAMIC 94 bool "Dynamic allocation of DMA bounce buffers" 95 default n 96 depends on SWIOTLB 97 help 98 This enables dynamic resizing of the software IO TLB. The kernel 99 starts with one memory pool at boot and it will allocate additional 100 pools as needed. To reduce run-time kernel memory requirements, you 101 may have to specify a smaller size of the initial pool using 102 "swiotlb=" on the kernel command line. 103 104 If unsure, say N. 105 106config DMA_BOUNCE_UNALIGNED_KMALLOC 107 bool 108 depends on SWIOTLB 109 110config DMA_RESTRICTED_POOL 111 bool "DMA Restricted Pool" 112 depends on OF && OF_RESERVED_MEM && SWIOTLB 113 help 114 This enables support for restricted DMA pools which provide a level of 115 DMA memory protection on systems with limited hardware protection 116 capabilities, such as those lacking an IOMMU. 117 118 For more information see 119 <Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt> 120 and <kernel/dma/swiotlb.c>. 121 If unsure, say "n". 122 123# 124# Should be selected if we can mmap non-coherent mappings to userspace. 125# The only thing that is really required is a way to set an uncached bit 126# in the pagetables 127# 128config DMA_NONCOHERENT_MMAP 129 default y if !MMU 130 bool 131 132config DMA_COHERENT_POOL 133 select GENERIC_ALLOCATOR 134 bool 135 136config DMA_GLOBAL_POOL 137 select DMA_DECLARE_COHERENT 138 depends on !ARCH_HAS_DMA_SET_UNCACHED 139 depends on !DMA_DIRECT_REMAP 140 bool 141 142config DMA_DIRECT_REMAP 143 bool 144 select DMA_COHERENT_POOL 145 select DMA_NONCOHERENT_MMAP 146 147# 148# Fallback to arch code for DMA allocations. This should eventually go away. 149# 150config ARCH_HAS_DMA_ALLOC 151 depends on !ARCH_HAS_DMA_SET_UNCACHED 152 depends on !DMA_DIRECT_REMAP 153 depends on !DMA_GLOBAL_POOL 154 bool 155 156config DMA_CMA 157 bool "DMA Contiguous Memory Allocator" 158 depends on HAVE_DMA_CONTIGUOUS && CMA 159 help 160 This enables the Contiguous Memory Allocator which allows drivers 161 to allocate big physically-contiguous blocks of memory for use with 162 hardware components that do not support I/O map nor scatter-gather. 163 164 You can disable CMA by specifying "cma=0" on the kernel's command 165 line. 166 167 For more information see <kernel/dma/contiguous.c>. 168 If unsure, say "n". 169 170if DMA_CMA 171 172config DMA_NUMA_CMA 173 bool "Enable separate DMA Contiguous Memory Area for NUMA Node" 174 depends on NUMA 175 help 176 Enable this option to get numa CMA areas so that NUMA devices 177 can get local memory by DMA coherent APIs. 178 179 You can set the size of pernuma CMA by specifying "cma_pernuma=size" 180 or set the node id and its size of CMA by specifying "numa_cma= 181 <node>:size[,<node>:size]" on the kernel's command line. 182 183comment "Default contiguous memory area size:" 184 185config CMA_SIZE_MBYTES 186 int "Size in Mega Bytes" 187 depends on !CMA_SIZE_SEL_PERCENTAGE 188 default 0 if X86 189 default 16 190 help 191 Defines the size (in MiB) of the default memory area for Contiguous 192 Memory Allocator. If the size of 0 is selected, CMA is disabled by 193 default, but it can be enabled by passing cma=size[MG] to the kernel. 194 195 196config CMA_SIZE_PERCENTAGE 197 int "Percentage of total memory" 198 depends on !CMA_SIZE_SEL_MBYTES 199 default 0 if X86 200 default 10 201 help 202 Defines the size of the default memory area for Contiguous Memory 203 Allocator as a percentage of the total memory in the system. 204 If 0 percent is selected, CMA is disabled by default, but it can be 205 enabled by passing cma=size[MG] to the kernel. 206 207choice 208 prompt "Selected region size" 209 default CMA_SIZE_SEL_MBYTES 210 211config CMA_SIZE_SEL_MBYTES 212 bool "Use mega bytes value only" 213 214config CMA_SIZE_SEL_PERCENTAGE 215 bool "Use percentage value only" 216 217config CMA_SIZE_SEL_MIN 218 bool "Use lower value (minimum)" 219 220config CMA_SIZE_SEL_MAX 221 bool "Use higher value (maximum)" 222 223endchoice 224 225config CMA_ALIGNMENT 226 int "Maximum PAGE_SIZE order of alignment for contiguous buffers" 227 range 2 12 228 default 8 229 help 230 DMA mapping framework by default aligns all buffers to the smallest 231 PAGE_SIZE order which is greater than or equal to the requested buffer 232 size. This works well for buffers up to a few hundreds kilobytes, but 233 for larger buffers it just a memory waste. With this parameter you can 234 specify the maximum PAGE_SIZE order for contiguous buffers. Larger 235 buffers will be aligned only to this specified order. The order is 236 expressed as a power of two multiplied by the PAGE_SIZE. 237 238 For example, if your system defaults to 4KiB pages, the order value 239 of 8 means that the buffers will be aligned up to 1MiB only. 240 241 If unsure, leave the default value "8". 242 243endif 244 245config DMA_API_DEBUG 246 bool "Enable debugging of DMA-API usage" 247 select NEED_DMA_MAP_STATE 248 help 249 Enable this option to debug the use of the DMA API by device drivers. 250 With this option you will be able to detect common bugs in device 251 drivers like double-freeing of DMA mappings or freeing mappings that 252 were never allocated. 253 254 This option causes a performance degradation. Use only if you want to 255 debug device drivers and dma interactions. 256 257 If unsure, say N. 258 259config DMA_API_DEBUG_SG 260 bool "Debug DMA scatter-gather usage" 261 default y 262 depends on DMA_API_DEBUG 263 help 264 Perform extra checking that callers of dma_map_sg() have respected the 265 appropriate segment length/boundary limits for the given device when 266 preparing DMA scatterlists. 267 268 This is particularly likely to have been overlooked in cases where the 269 dma_map_sg() API is used for general bulk mapping of pages rather than 270 preparing literal scatter-gather descriptors, where there is a risk of 271 unexpected behaviour from DMA API implementations if the scatterlist 272 is technically out-of-spec. 273 274 If unsure, say N. 275 276config DMA_MAP_BENCHMARK 277 bool "Enable benchmarking of streaming DMA mapping" 278 depends on DEBUG_FS 279 help 280 Provides /sys/kernel/debug/dma_map_benchmark that helps with testing 281 performance of dma_(un)map_page. 282 283 See tools/testing/selftests/dma/dma_map_benchmark.c 284