1 # SPDX-License-Identifier: GPL-2.0-only
15 # IOMMU drivers that can bypass the IOMMU code and optionally use the direct
16 # mapping fast path should select this option and set the dma_ops_bypass
17 # flag in struct device where applicable
22 config NEED_SG_DMA_LENGTH
25 config NEED_DMA_MAP_STATE
28 config ARCH_DMA_ADDR_T_64BIT
29 def_bool 64BIT || PHYS_ADDR_T_64BIT
31 config ARCH_HAS_DMA_COHERENCE_H
34 config ARCH_HAS_DMA_SET_MASK
38 # Select this option if the architecture needs special handling for
39 # DMA_ATTR_WRITE_COMBINE. Normally the "uncached" mapping should be what
40 # people thing of when saying write combine, so very few platforms should
41 # need to enable this.
43 config ARCH_HAS_DMA_WRITE_COMBINE
46 config DMA_DECLARE_COHERENT
49 config ARCH_HAS_SETUP_DMA_OPS
52 config ARCH_HAS_TEARDOWN_DMA_OPS
55 config ARCH_HAS_SYNC_DMA_FOR_DEVICE
58 config ARCH_HAS_SYNC_DMA_FOR_CPU
60 select NEED_DMA_MAP_STATE
62 config ARCH_HAS_SYNC_DMA_FOR_CPU_ALL
65 config ARCH_HAS_DMA_PREP_COHERENT
68 config ARCH_HAS_FORCE_DMA_UNENCRYPTED
71 config DMA_NONCOHERENT_CACHE_SYNC
81 select NEED_DMA_MAP_STATE
84 # Should be selected if we can mmap non-coherent mappings to userspace.
85 # The only thing that is really required is a way to set an uncached bit
88 config DMA_NONCOHERENT_MMAP
92 config DMA_COHERENT_POOL
93 select GENERIC_ALLOCATOR
99 select DMA_NONCOHERENT_MMAP
101 config DMA_DIRECT_REMAP
104 select DMA_COHERENT_POOL
107 bool "DMA Contiguous Memory Allocator"
108 depends on HAVE_DMA_CONTIGUOUS && CMA
110 This enables the Contiguous Memory Allocator which allows drivers
111 to allocate big physically-contiguous blocks of memory for use with
112 hardware components that do not support I/O map nor scatter-gather.
114 You can disable CMA by specifying "cma=0" on the kernel's command
117 For more information see <include/linux/dma-contiguous.h>.
121 comment "Default contiguous memory area size:"
123 config CMA_SIZE_MBYTES
124 int "Size in Mega Bytes"
125 depends on !CMA_SIZE_SEL_PERCENTAGE
129 Defines the size (in MiB) of the default memory area for Contiguous
130 Memory Allocator. If the size of 0 is selected, CMA is disabled by
131 default, but it can be enabled by passing cma=size[MG] to the kernel.
134 config CMA_SIZE_PERCENTAGE
135 int "Percentage of total memory"
136 depends on !CMA_SIZE_SEL_MBYTES
140 Defines the size of the default memory area for Contiguous Memory
141 Allocator as a percentage of the total memory in the system.
142 If 0 percent is selected, CMA is disabled by default, but it can be
143 enabled by passing cma=size[MG] to the kernel.
146 prompt "Selected region size"
147 default CMA_SIZE_SEL_MBYTES
149 config CMA_SIZE_SEL_MBYTES
150 bool "Use mega bytes value only"
152 config CMA_SIZE_SEL_PERCENTAGE
153 bool "Use percentage value only"
155 config CMA_SIZE_SEL_MIN
156 bool "Use lower value (minimum)"
158 config CMA_SIZE_SEL_MAX
159 bool "Use higher value (maximum)"
164 int "Maximum PAGE_SIZE order of alignment for contiguous buffers"
168 DMA mapping framework by default aligns all buffers to the smallest
169 PAGE_SIZE order which is greater than or equal to the requested buffer
170 size. This works well for buffers up to a few hundreds kilobytes, but
171 for larger buffers it just a memory waste. With this parameter you can
172 specify the maximum PAGE_SIZE order for contiguous buffers. Larger
173 buffers will be aligned only to this specified order. The order is
174 expressed as a power of two multiplied by the PAGE_SIZE.
176 For example, if your system defaults to 4KiB pages, the order value
177 of 8 means that the buffers will be aligned up to 1MiB only.
179 If unsure, leave the default value "8".
184 bool "Enable debugging of DMA-API usage"
185 select NEED_DMA_MAP_STATE
187 Enable this option to debug the use of the DMA API by device drivers.
188 With this option you will be able to detect common bugs in device
189 drivers like double-freeing of DMA mappings or freeing mappings that
190 were never allocated.
192 This option causes a performance degradation. Use only if you want to
193 debug device drivers and dma interactions.
197 config DMA_API_DEBUG_SG
198 bool "Debug DMA scatter-gather usage"
200 depends on DMA_API_DEBUG
202 Perform extra checking that callers of dma_map_sg() have respected the
203 appropriate segment length/boundary limits for the given device when
204 preparing DMA scatterlists.
206 This is particularly likely to have been overlooked in cases where the
207 dma_map_sg() API is used for general bulk mapping of pages rather than
208 preparing literal scatter-gather descriptors, where there is a risk of
209 unexpected behaviour from DMA API implementations if the scatterlist
210 is technically out-of-spec.