tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1Generic on-chip SRAM
2
3Simple IO memory regions to be managed by the genalloc API.
4
5Required properties:
6
7- compatible : mmio-sram or atmel,sama5d2-securam
8
9- reg : SRAM iomem address range
10
11Reserving sram areas:
12---------------------
13
14Each child of the sram node specifies a region of reserved memory. Each
15child node should use a 'reg' property to specify a specific range of
16reserved memory.
17
18Following the generic-names recommended practice, node names should
19reflect the purpose of the node. Unit address (@<address>) should be
20appended to the name.
21
22Required properties in the sram node:
23
24- #address-cells, #size-cells : should use the same values as the root node
25- ranges : standard definition, should translate from local addresses
26 within the sram to bus addresses
27
28Optional properties in the sram node:
29
30- no-memory-wc : the flag indicating, that SRAM memory region has not to
31 be remapped as write combining. WC is used by default.
32
33Required properties in the area nodes:
34
35- reg : iomem address range, relative to the SRAM range
36
37Optional properties in the area nodes:
38
39- compatible : standard definition, should contain a vendor specific string
40 in the form <vendor>,[<device>-]<usage>
41- pool : indicates that the particular reserved SRAM area is addressable
42 and in use by another device or devices
43- export : indicates that the reserved SRAM area may be accessed outside
44 of the kernel, e.g. by bootloader or userspace
45- protect-exec : Same as 'pool' above but with the additional
46 constraint that code wil be run from the region and
47 that the memory is maintained as read-only, executable
48 during code execution. NOTE: This region must be page
49 aligned on start and end in order to properly allow
50 manipulation of the page attributes.
51- label : the name for the reserved partition, if omitted, the label
52 is taken from the node name excluding the unit address.
53
54Example:
55
56sram: sram@5c000000 {
57 compatible = "mmio-sram";
58 reg = <0x5c000000 0x40000>; /* 256 KiB SRAM at address 0x5c000000 */
59
60 #address-cells = <1>;
61 #size-cells = <1>;
62 ranges = <0 0x5c000000 0x40000>;
63
64 smp-sram@100 {
65 compatible = "socvendor,smp-sram";
66 reg = <0x100 0x50>;
67 };
68
69 device-sram@1000 {
70 reg = <0x1000 0x1000>;
71 pool;
72 };
73
74 exported@20000 {
75 reg = <0x20000 0x20000>;
76 export;
77 };
78};