1 # SPDX-License-Identifier: GPL-2.0-only
12 # IOMMU drivers that can bypass the IOMMU code and optionally use the direct
13 # mapping fast path should select this option and set the dma_ops_bypass
14 # flag in struct device where applicable
19 config NEED_SG_DMA_LENGTH
22 config NEED_DMA_MAP_STATE
25 config ARCH_DMA_ADDR_T_64BIT
26 def_bool 64BIT || PHYS_ADDR_T_64BIT
28 config ARCH_HAS_DMA_COHERENCE_H
31 config ARCH_HAS_DMA_SET_MASK
35 # Select this option if the architecture needs special handling for
36 # DMA_ATTR_WRITE_COMBINE. Normally the "uncached" mapping should be what
37 # people thing of when saying write combine, so very few platforms should
38 # need to enable this.
40 config ARCH_HAS_DMA_WRITE_COMBINE
43 config DMA_DECLARE_COHERENT
46 config ARCH_HAS_SETUP_DMA_OPS
49 config ARCH_HAS_TEARDOWN_DMA_OPS
52 config ARCH_HAS_SYNC_DMA_FOR_DEVICE
55 config ARCH_HAS_SYNC_DMA_FOR_CPU
57 select NEED_DMA_MAP_STATE
59 config ARCH_HAS_SYNC_DMA_FOR_CPU_ALL
62 config ARCH_HAS_DMA_PREP_COHERENT
65 config ARCH_HAS_FORCE_DMA_UNENCRYPTED
68 config DMA_NONCOHERENT_CACHE_SYNC
78 select NEED_DMA_MAP_STATE
81 # Should be selected if we can mmap non-coherent mappings to userspace.
82 # The only thing that is really required is a way to set an uncached bit
85 config DMA_NONCOHERENT_MMAP
89 config DMA_COHERENT_POOL
90 select GENERIC_ALLOCATOR
96 select DMA_NONCOHERENT_MMAP
98 config DMA_DIRECT_REMAP
101 select DMA_COHERENT_POOL
104 bool "DMA Contiguous Memory Allocator"
105 depends on HAVE_DMA_CONTIGUOUS && CMA
107 This enables the Contiguous Memory Allocator which allows drivers
108 to allocate big physically-contiguous blocks of memory for use with
109 hardware components that do not support I/O map nor scatter-gather.
111 You can disable CMA by specifying "cma=0" on the kernel's command
114 For more information see <include/linux/dma-contiguous.h>.
118 comment "Default contiguous memory area size:"
120 config CMA_SIZE_MBYTES
121 int "Size in Mega Bytes"
122 depends on !CMA_SIZE_SEL_PERCENTAGE
126 Defines the size (in MiB) of the default memory area for Contiguous
127 Memory Allocator. If the size of 0 is selected, CMA is disabled by
128 default, but it can be enabled by passing cma=size[MG] to the kernel.
131 config CMA_SIZE_PERCENTAGE
132 int "Percentage of total memory"
133 depends on !CMA_SIZE_SEL_MBYTES
137 Defines the size of the default memory area for Contiguous Memory
138 Allocator as a percentage of the total memory in the system.
139 If 0 percent is selected, CMA is disabled by default, but it can be
140 enabled by passing cma=size[MG] to the kernel.
143 prompt "Selected region size"
144 default CMA_SIZE_SEL_MBYTES
146 config CMA_SIZE_SEL_MBYTES
147 bool "Use mega bytes value only"
149 config CMA_SIZE_SEL_PERCENTAGE
150 bool "Use percentage value only"
152 config CMA_SIZE_SEL_MIN
153 bool "Use lower value (minimum)"
155 config CMA_SIZE_SEL_MAX
156 bool "Use higher value (maximum)"
161 int "Maximum PAGE_SIZE order of alignment for contiguous buffers"
165 DMA mapping framework by default aligns all buffers to the smallest
166 PAGE_SIZE order which is greater than or equal to the requested buffer
167 size. This works well for buffers up to a few hundreds kilobytes, but
168 for larger buffers it just a memory waste. With this parameter you can
169 specify the maximum PAGE_SIZE order for contiguous buffers. Larger
170 buffers will be aligned only to this specified order. The order is
171 expressed as a power of two multiplied by the PAGE_SIZE.
173 For example, if your system defaults to 4KiB pages, the order value
174 of 8 means that the buffers will be aligned up to 1MiB only.
176 If unsure, leave the default value "8".
181 bool "Enable debugging of DMA-API usage"
182 select NEED_DMA_MAP_STATE
184 Enable this option to debug the use of the DMA API by device drivers.
185 With this option you will be able to detect common bugs in device
186 drivers like double-freeing of DMA mappings or freeing mappings that
187 were never allocated.
189 This also attempts to catch cases where a page owned by DMA is
190 accessed by the cpu in a way that could cause data corruption. For
191 example, this enables cow_user_page() to check that the source page is
194 This option causes a performance degradation. Use only if you want to
195 debug device drivers and dma interactions.
199 config DMA_API_DEBUG_SG
200 bool "Debug DMA scatter-gather usage"
202 depends on DMA_API_DEBUG
204 Perform extra checking that callers of dma_map_sg() have respected the
205 appropriate segment length/boundary limits for the given device when
206 preparing DMA scatterlists.
208 This is particularly likely to have been overlooked in cases where the
209 dma_map_sg() API is used for general bulk mapping of pages rather than
210 preparing literal scatter-gather descriptors, where there is a risk of
211 unexpected behaviour from DMA API implementations if the scatterlist
212 is technically out-of-spec.