xref: /openbmc/linux/kernel/dma/Kconfig (revision 95298d63)
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_COHERENT_POOL
77	bool
78
79config DMA_REMAP
80	bool
81	depends on MMU
82	select GENERIC_ALLOCATOR
83	select DMA_NONCOHERENT_MMAP
84
85config DMA_DIRECT_REMAP
86	bool
87	select DMA_REMAP
88	select DMA_COHERENT_POOL
89
90config DMA_CMA
91	bool "DMA Contiguous Memory Allocator"
92	depends on HAVE_DMA_CONTIGUOUS && CMA
93	help
94	  This enables the Contiguous Memory Allocator which allows drivers
95	  to allocate big physically-contiguous blocks of memory for use with
96	  hardware components that do not support I/O map nor scatter-gather.
97
98	  You can disable CMA by specifying "cma=0" on the kernel's command
99	  line.
100
101	  For more information see <include/linux/dma-contiguous.h>.
102	  If unsure, say "n".
103
104if  DMA_CMA
105comment "Default contiguous memory area size:"
106
107config CMA_SIZE_MBYTES
108	int "Size in Mega Bytes"
109	depends on !CMA_SIZE_SEL_PERCENTAGE
110	default 0 if X86
111	default 16
112	help
113	  Defines the size (in MiB) of the default memory area for Contiguous
114	  Memory Allocator.  If the size of 0 is selected, CMA is disabled by
115	  default, but it can be enabled by passing cma=size[MG] to the kernel.
116
117
118config CMA_SIZE_PERCENTAGE
119	int "Percentage of total memory"
120	depends on !CMA_SIZE_SEL_MBYTES
121	default 0 if X86
122	default 10
123	help
124	  Defines the size of the default memory area for Contiguous Memory
125	  Allocator as a percentage of the total memory in the system.
126	  If 0 percent is selected, CMA is disabled by default, but it can be
127	  enabled by passing cma=size[MG] to the kernel.
128
129choice
130	prompt "Selected region size"
131	default CMA_SIZE_SEL_MBYTES
132
133config CMA_SIZE_SEL_MBYTES
134	bool "Use mega bytes value only"
135
136config CMA_SIZE_SEL_PERCENTAGE
137	bool "Use percentage value only"
138
139config CMA_SIZE_SEL_MIN
140	bool "Use lower value (minimum)"
141
142config CMA_SIZE_SEL_MAX
143	bool "Use higher value (maximum)"
144
145endchoice
146
147config CMA_ALIGNMENT
148	int "Maximum PAGE_SIZE order of alignment for contiguous buffers"
149	range 4 12
150	default 8
151	help
152	  DMA mapping framework by default aligns all buffers to the smallest
153	  PAGE_SIZE order which is greater than or equal to the requested buffer
154	  size. This works well for buffers up to a few hundreds kilobytes, but
155	  for larger buffers it just a memory waste. With this parameter you can
156	  specify the maximum PAGE_SIZE order for contiguous buffers. Larger
157	  buffers will be aligned only to this specified order. The order is
158	  expressed as a power of two multiplied by the PAGE_SIZE.
159
160	  For example, if your system defaults to 4KiB pages, the order value
161	  of 8 means that the buffers will be aligned up to 1MiB only.
162
163	  If unsure, leave the default value "8".
164
165endif
166
167config DMA_API_DEBUG
168	bool "Enable debugging of DMA-API usage"
169	select NEED_DMA_MAP_STATE
170	help
171	  Enable this option to debug the use of the DMA API by device drivers.
172	  With this option you will be able to detect common bugs in device
173	  drivers like double-freeing of DMA mappings or freeing mappings that
174	  were never allocated.
175
176	  This also attempts to catch cases where a page owned by DMA is
177	  accessed by the cpu in a way that could cause data corruption.  For
178	  example, this enables cow_user_page() to check that the source page is
179	  not undergoing DMA.
180
181	  This option causes a performance degradation.  Use only if you want to
182	  debug device drivers and dma interactions.
183
184	  If unsure, say N.
185
186config DMA_API_DEBUG_SG
187	bool "Debug DMA scatter-gather usage"
188	default y
189	depends on DMA_API_DEBUG
190	help
191	  Perform extra checking that callers of dma_map_sg() have respected the
192	  appropriate segment length/boundary limits for the given device when
193	  preparing DMA scatterlists.
194
195	  This is particularly likely to have been overlooked in cases where the
196	  dma_map_sg() API is used for general bulk mapping of pages rather than
197	  preparing literal scatter-gather descriptors, where there is a risk of
198	  unexpected behaviour from DMA API implementations if the scatterlist
199	  is technically out-of-spec.
200
201	  If unsure, say N.
202