xref: /linux/Documentation/devicetree/bindings/cpufreq/cpufreq-st.txt (revision ffb1e76f4f32d2b8ea4189df0484980370476395) 
1Binding for ST's CPUFreq driver
2===============================
3
4ST's CPUFreq driver attempts to read 'process' and 'version' attributes
5from the SoC, then supplies the OPP framework with 'prop' and 'supported
6hardware' information respectively.  The framework is then able to read
7the DT and operate in the usual way.
8
9Frequency Scaling only
10----------------------
11
12No vendor specific driver required for this.
13
14Located in CPU's node:
15
16- operating-points		: [See: ../power/opp-v1.yaml]
17
18Example [safe]
19--------------
20
21cpus {
22	cpu@0 {
23				 /* kHz     uV   */
24		operating-points = <1500000 0
25				    1200000 0
26				    800000  0
27				    500000  0>;
28	};
29};
30
31Dynamic Voltage and Frequency Scaling (DVFS)
32--------------------------------------------
33
34This requires the ST CPUFreq driver to supply 'process' and 'version' info.
35
36Located in CPU's node:
37
38- operating-points-v2		: [See ../power/opp-v2.yaml]
39
40Example [unsafe]
41----------------
42
43cpus {
44	cpu@0 {
45		operating-points-v2	= <&cpu0_opp_table>;
46	};
47};
48
49cpu0_opp_table: opp_table {
50	compatible = "operating-points-v2";
51
52	/* ############################################################### */
53	/* # WARNING: Do not attempt to copy/replicate these nodes,      # */
54	/* #          they are only to be supplied by the bootloader !!! # */
55	/* ############################################################### */
56	opp0 {
57		/*			   Major       Minor       Substrate */
58		/*			   2           all         all       */
59		opp-supported-hw	= <0x00000004  0xffffffff  0xffffffff>;
60		opp-hz			= /bits/ 64 <1500000000>;
61		clock-latency-ns	= <10000000>;
62
63		opp-microvolt-pcode0	= <1200000>;
64		opp-microvolt-pcode1	= <1200000>;
65		opp-microvolt-pcode2	= <1200000>;
66		opp-microvolt-pcode3	= <1200000>;
67		opp-microvolt-pcode4	= <1170000>;
68		opp-microvolt-pcode5	= <1140000>;
69		opp-microvolt-pcode6	= <1100000>;
70		opp-microvolt-pcode7	= <1070000>;
71	};
72
73	opp1 {
74		/*			   Major       Minor       Substrate */
75		/*			   all         all         all       */
76		opp-supported-hw	= <0xffffffff  0xffffffff  0xffffffff>;
77		opp-hz			= /bits/ 64 <1200000000>;
78		clock-latency-ns	= <10000000>;
79
80		opp-microvolt-pcode0	= <1110000>;
81		opp-microvolt-pcode1	= <1150000>;
82		opp-microvolt-pcode2	= <1100000>;
83		opp-microvolt-pcode3	= <1080000>;
84		opp-microvolt-pcode4	= <1040000>;
85		opp-microvolt-pcode5	= <1020000>;
86		opp-microvolt-pcode6	= <980000>;
87		opp-microvolt-pcode7	= <930000>;
88	};
89};
90