xref: /linux/Documentation/devicetree/bindings/soc/fsl/cpm_qe/cpm.txt (revision c532de5a67a70f8533d495f8f2aaa9a0491c3ad0)
1* Freescale Communications Processor Module
2
3NOTE: This is an interim binding, and will likely change slightly,
4as more devices are supported.  The QE bindings especially are
5incomplete.
6
7* Root CPM node
8
9Properties:
10- compatible : "fsl,cpm1", "fsl,cpm2", or "fsl,qe".
11- reg : A 48-byte region beginning with CPCR.
12
13Example:
14     cpm@119c0 {
15	#address-cells = <1>;
16	#size-cells = <1>;
17	#interrupt-cells = <2>;
18	compatible = "fsl,mpc8272-cpm", "fsl,cpm2";
19	reg = <119c0 30>;
20     }
21
22* Properties common to multiple CPM/QE devices
23
24- fsl,cpm-command : This value is ORed with the opcode and command flag
25                    to specify the device on which a CPM command operates.
26
27- fsl,cpm-brg : Indicates which baud rate generator the device
28                is associated with.  If absent, an unused BRG
29                should be dynamically allocated.  If zero, the
30                device uses an external clock rather than a BRG.
31
32- reg : Unless otherwise specified, the first resource represents the
33        scc/fcc/ucc registers, and the second represents the device's
34        parameter RAM region (if it has one).
35
36* Multi-User RAM (MURAM)
37
38The multi-user/dual-ported RAM is expressed as a bus under the CPM node.
39
40Ranges must be set up subject to the following restrictions:
41
42- Children's reg nodes must be offsets from the start of all muram, even
43  if the user-data area does not begin at zero.
44- If multiple range entries are used, the difference between the parent
45  address and the child address must be the same in all, so that a single
46  mapping can cover them all while maintaining the ability to determine
47  CPM-side offsets with pointer subtraction.  It is recommended that
48  multiple range entries not be used.
49- A child address of zero must be translatable, even if no reg resources
50  contain it.
51
52A child "data" node must exist, compatible with "fsl,cpm-muram-data", to
53indicate the portion of muram that is usable by the OS for arbitrary
54purposes.  The data node may have an arbitrary number of reg resources,
55all of which contribute to the allocatable muram pool.
56
57Example, based on mpc8272:
58	muram@0 {
59		#address-cells = <1>;
60		#size-cells = <1>;
61		ranges = <0 0 10000>;
62
63		data@0 {
64			compatible = "fsl,cpm-muram-data";
65			reg = <0 2000 9800 800>;
66		};
67	};
68