1# SPDX-License-Identifier: GPL-2.0-only 2 3config HAS_DMA 4 bool 5 depends on !NO_DMA 6 default y 7 8config NEED_SG_DMA_LENGTH 9 bool 10 11config NEED_DMA_MAP_STATE 12 bool 13 14config ARCH_DMA_ADDR_T_64BIT 15 def_bool 64BIT || PHYS_ADDR_T_64BIT 16 17config ARCH_HAS_DMA_COHERENCE_H 18 bool 19 20config ARCH_HAS_DMA_SET_MASK 21 bool 22 23# 24# Select this option if the architecture needs special handling for 25# DMA_ATTR_WRITE_COMBINE. Normally the "uncached" mapping should be what 26# people thing of when saying write combine, so very few platforms should 27# need to enable this. 28# 29config ARCH_HAS_DMA_WRITE_COMBINE 30 bool 31 32config DMA_DECLARE_COHERENT 33 bool 34 35config ARCH_HAS_SETUP_DMA_OPS 36 bool 37 38config ARCH_HAS_TEARDOWN_DMA_OPS 39 bool 40 41config ARCH_HAS_SYNC_DMA_FOR_DEVICE 42 bool 43 44config ARCH_HAS_SYNC_DMA_FOR_CPU 45 bool 46 select NEED_DMA_MAP_STATE 47 48config ARCH_HAS_SYNC_DMA_FOR_CPU_ALL 49 bool 50 51config ARCH_HAS_DMA_PREP_COHERENT 52 bool 53 54config ARCH_HAS_FORCE_DMA_UNENCRYPTED 55 bool 56 57config DMA_NONCOHERENT_CACHE_SYNC 58 bool 59 60config DMA_VIRT_OPS 61 bool 62 depends on HAS_DMA 63 64config SWIOTLB 65 bool 66 select NEED_DMA_MAP_STATE 67 68# 69# Should be selected if we can mmap non-coherent mappings to userspace. 70# The only thing that is really required is a way to set an uncached bit 71# in the pagetables 72# 73config DMA_NONCOHERENT_MMAP 74 bool 75 76config DMA_REMAP 77 depends on MMU 78 select GENERIC_ALLOCATOR 79 select DMA_NONCOHERENT_MMAP 80 bool 81 82config DMA_DIRECT_REMAP 83 bool 84 select DMA_REMAP 85 86config DMA_CMA 87 bool "DMA Contiguous Memory Allocator" 88 depends on HAVE_DMA_CONTIGUOUS && CMA 89 help 90 This enables the Contiguous Memory Allocator which allows drivers 91 to allocate big physically-contiguous blocks of memory for use with 92 hardware components that do not support I/O map nor scatter-gather. 93 94 You can disable CMA by specifying "cma=0" on the kernel's command 95 line. 96 97 For more information see <include/linux/dma-contiguous.h>. 98 If unsure, say "n". 99 100if DMA_CMA 101comment "Default contiguous memory area size:" 102 103config CMA_SIZE_MBYTES 104 int "Size in Mega Bytes" 105 depends on !CMA_SIZE_SEL_PERCENTAGE 106 default 0 if X86 107 default 16 108 help 109 Defines the size (in MiB) of the default memory area for Contiguous 110 Memory Allocator. If the size of 0 is selected, CMA is disabled by 111 default, but it can be enabled by passing cma=size[MG] to the kernel. 112 113 114config CMA_SIZE_PERCENTAGE 115 int "Percentage of total memory" 116 depends on !CMA_SIZE_SEL_MBYTES 117 default 0 if X86 118 default 10 119 help 120 Defines the size of the default memory area for Contiguous Memory 121 Allocator as a percentage of the total memory in the system. 122 If 0 percent is selected, CMA is disabled by default, but it can be 123 enabled by passing cma=size[MG] to the kernel. 124 125choice 126 prompt "Selected region size" 127 default CMA_SIZE_SEL_MBYTES 128 129config CMA_SIZE_SEL_MBYTES 130 bool "Use mega bytes value only" 131 132config CMA_SIZE_SEL_PERCENTAGE 133 bool "Use percentage value only" 134 135config CMA_SIZE_SEL_MIN 136 bool "Use lower value (minimum)" 137 138config CMA_SIZE_SEL_MAX 139 bool "Use higher value (maximum)" 140 141endchoice 142 143config CMA_ALIGNMENT 144 int "Maximum PAGE_SIZE order of alignment for contiguous buffers" 145 range 4 12 146 default 8 147 help 148 DMA mapping framework by default aligns all buffers to the smallest 149 PAGE_SIZE order which is greater than or equal to the requested buffer 150 size. This works well for buffers up to a few hundreds kilobytes, but 151 for larger buffers it just a memory waste. With this parameter you can 152 specify the maximum PAGE_SIZE order for contiguous buffers. Larger 153 buffers will be aligned only to this specified order. The order is 154 expressed as a power of two multiplied by the PAGE_SIZE. 155 156 For example, if your system defaults to 4KiB pages, the order value 157 of 8 means that the buffers will be aligned up to 1MiB only. 158 159 If unsure, leave the default value "8". 160 161endif 162 163config DMA_API_DEBUG 164 bool "Enable debugging of DMA-API usage" 165 select NEED_DMA_MAP_STATE 166 help 167 Enable this option to debug the use of the DMA API by device drivers. 168 With this option you will be able to detect common bugs in device 169 drivers like double-freeing of DMA mappings or freeing mappings that 170 were never allocated. 171 172 This also attempts to catch cases where a page owned by DMA is 173 accessed by the cpu in a way that could cause data corruption. For 174 example, this enables cow_user_page() to check that the source page is 175 not undergoing DMA. 176 177 This option causes a performance degradation. Use only if you want to 178 debug device drivers and dma interactions. 179 180 If unsure, say N. 181 182config DMA_API_DEBUG_SG 183 bool "Debug DMA scatter-gather usage" 184 default y 185 depends on DMA_API_DEBUG 186 help 187 Perform extra checking that callers of dma_map_sg() have respected the 188 appropriate segment length/boundary limits for the given device when 189 preparing DMA scatterlists. 190 191 This is particularly likely to have been overlooked in cases where the 192 dma_map_sg() API is used for general bulk mapping of pages rather than 193 preparing literal scatter-gather descriptors, where there is a risk of 194 unexpected behaviour from DMA API implementations if the scatterlist 195 is technically out-of-spec. 196 197 If unsure, say N. 198