kernel/dma/Kconfig

   1 # SPDX-License-Identifier: GPL-2.0-only
   2
   3 config HAS_DMA
   4         bool
   5         depends on !NO_DMA
   6         default y
   7
   8 config NEED_SG_DMA_LENGTH
   9         bool
  10
  11 config NEED_DMA_MAP_STATE
  12         bool
  13
  14 config ARCH_DMA_ADDR_T_64BIT
  15         def_bool 64BIT || PHYS_ADDR_T_64BIT
  16
  17 config ARCH_HAS_DMA_COHERENCE_H
  18         bool
  19
  20 config 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 #
  29 config ARCH_HAS_DMA_WRITE_COMBINE
  30         bool
  31
  32 config DMA_DECLARE_COHERENT
  33         bool
  34
  35 config ARCH_HAS_SETUP_DMA_OPS
  36         bool
  37
  38 config ARCH_HAS_TEARDOWN_DMA_OPS
  39         bool
  40
  41 config ARCH_HAS_SYNC_DMA_FOR_DEVICE
  42         bool
  43
  44 config ARCH_HAS_SYNC_DMA_FOR_CPU
  45         bool
  46         select NEED_DMA_MAP_STATE
  47
  48 config ARCH_HAS_SYNC_DMA_FOR_CPU_ALL
  49         bool
  50
  51 config ARCH_HAS_DMA_PREP_COHERENT
  52         bool
  53
  54 config ARCH_HAS_FORCE_DMA_UNENCRYPTED
  55         bool
  56
  57 config DMA_NONCOHERENT_CACHE_SYNC
  58         bool
  59
  60 config DMA_VIRT_OPS
  61         bool
  62         depends on HAS_DMA
  63
  64 config 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 #
  73 config DMA_NONCOHERENT_MMAP
  74         bool
  75
  76 config DMA_REMAP
  77         depends on MMU
  78         select GENERIC_ALLOCATOR
  79         select DMA_NONCOHERENT_MMAP
  80         bool
  81
  82 config DMA_DIRECT_REMAP
  83         bool
  84         select DMA_REMAP
  85
  86 config 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
 100 if  DMA_CMA
 101 comment "Default contiguous memory area size:"
 102
 103 config 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
 114 config 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
 125 choice
 126         prompt "Selected region size"
 127         default CMA_SIZE_SEL_MBYTES
 128
 129 config CMA_SIZE_SEL_MBYTES
 130         bool "Use mega bytes value only"
 131
 132 config CMA_SIZE_SEL_PERCENTAGE
 133         bool "Use percentage value only"
 134
 135 config CMA_SIZE_SEL_MIN
 136         bool "Use lower value (minimum)"
 137
 138 config CMA_SIZE_SEL_MAX
 139         bool "Use higher value (maximum)"
 140
 141 endchoice
 142
 143 config 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
 161 endif
 162
 163 config 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
 182 config 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.