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 default y if !MMU 75 bool 76 77config DMA_COHERENT_POOL 78 select GENERIC_ALLOCATOR 79 bool 80 81config DMA_REMAP 82 bool 83 depends on MMU 84 select DMA_NONCOHERENT_MMAP 85 86config DMA_DIRECT_REMAP 87 bool 88 select DMA_REMAP 89 select DMA_COHERENT_POOL 90 91config DMA_CMA 92 bool "DMA Contiguous Memory Allocator" 93 depends on HAVE_DMA_CONTIGUOUS && CMA 94 help 95 This enables the Contiguous Memory Allocator which allows drivers 96 to allocate big physically-contiguous blocks of memory for use with 97 hardware components that do not support I/O map nor scatter-gather. 98 99 You can disable CMA by specifying "cma=0" on the kernel's command 100 line. 101 102 For more information see <include/linux/dma-contiguous.h>. 103 If unsure, say "n". 104 105if DMA_CMA 106comment "Default contiguous memory area size:" 107 108config CMA_SIZE_MBYTES 109 int "Size in Mega Bytes" 110 depends on !CMA_SIZE_SEL_PERCENTAGE 111 default 0 if X86 112 default 16 113 help 114 Defines the size (in MiB) of the default memory area for Contiguous 115 Memory Allocator. If the size of 0 is selected, CMA is disabled by 116 default, but it can be enabled by passing cma=size[MG] to the kernel. 117 118 119config CMA_SIZE_PERCENTAGE 120 int "Percentage of total memory" 121 depends on !CMA_SIZE_SEL_MBYTES 122 default 0 if X86 123 default 10 124 help 125 Defines the size of the default memory area for Contiguous Memory 126 Allocator as a percentage of the total memory in the system. 127 If 0 percent is selected, CMA is disabled by default, but it can be 128 enabled by passing cma=size[MG] to the kernel. 129 130choice 131 prompt "Selected region size" 132 default CMA_SIZE_SEL_MBYTES 133 134config CMA_SIZE_SEL_MBYTES 135 bool "Use mega bytes value only" 136 137config CMA_SIZE_SEL_PERCENTAGE 138 bool "Use percentage value only" 139 140config CMA_SIZE_SEL_MIN 141 bool "Use lower value (minimum)" 142 143config CMA_SIZE_SEL_MAX 144 bool "Use higher value (maximum)" 145 146endchoice 147 148config CMA_ALIGNMENT 149 int "Maximum PAGE_SIZE order of alignment for contiguous buffers" 150 range 4 12 151 default 8 152 help 153 DMA mapping framework by default aligns all buffers to the smallest 154 PAGE_SIZE order which is greater than or equal to the requested buffer 155 size. This works well for buffers up to a few hundreds kilobytes, but 156 for larger buffers it just a memory waste. With this parameter you can 157 specify the maximum PAGE_SIZE order for contiguous buffers. Larger 158 buffers will be aligned only to this specified order. The order is 159 expressed as a power of two multiplied by the PAGE_SIZE. 160 161 For example, if your system defaults to 4KiB pages, the order value 162 of 8 means that the buffers will be aligned up to 1MiB only. 163 164 If unsure, leave the default value "8". 165 166endif 167 168config DMA_API_DEBUG 169 bool "Enable debugging of DMA-API usage" 170 select NEED_DMA_MAP_STATE 171 help 172 Enable this option to debug the use of the DMA API by device drivers. 173 With this option you will be able to detect common bugs in device 174 drivers like double-freeing of DMA mappings or freeing mappings that 175 were never allocated. 176 177 This also attempts to catch cases where a page owned by DMA is 178 accessed by the cpu in a way that could cause data corruption. For 179 example, this enables cow_user_page() to check that the source page is 180 not undergoing DMA. 181 182 This option causes a performance degradation. Use only if you want to 183 debug device drivers and dma interactions. 184 185 If unsure, say N. 186 187config DMA_API_DEBUG_SG 188 bool "Debug DMA scatter-gather usage" 189 default y 190 depends on DMA_API_DEBUG 191 help 192 Perform extra checking that callers of dma_map_sg() have respected the 193 appropriate segment length/boundary limits for the given device when 194 preparing DMA scatterlists. 195 196 This is particularly likely to have been overlooked in cases where the 197 dma_map_sg() API is used for general bulk mapping of pages rather than 198 preparing literal scatter-gather descriptors, where there is a risk of 199 unexpected behaviour from DMA API implementations if the scatterlist 200 is technically out-of-spec. 201 202 If unsure, say N. 203