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authorLee Jones <lee.jones@linaro.org>2015-12-10 12:42:17 +0300
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2015-12-12 04:55:22 +0300
commitb122bcd94743239cc26a5732fef87b28d7f5c22a (patch)
treeb18bae92710e2cf86b30eee3cd8bc77f1447d9b6 /Documentation/devicetree/bindings/cpufreq
parentab0ea257fc58d8742f73f50fba3797dfe001aa3c (diff)
downloadlinux-b122bcd94743239cc26a5732fef87b28d7f5c22a.tar.xz
dt: cpufreq: st: Provide bindings for ST's CPUFreq implementation
Acked-by: Rob Herring <robh@kernel.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Lee Jones <lee.jones@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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+Binding for ST's CPUFreq driver
+===============================
+
+ST's CPUFreq driver attempts to read 'process' and 'version' attributes
+from the SoC, then supplies the OPP framework with 'prop' and 'supported
+hardware' information respectively. The framework is then able to read
+the DT and operate in the usual way.
+
+For more information about the expected DT format [See: ../opp/opp.txt].
+
+Frequency Scaling only
+----------------------
+
+No vendor specific driver required for this.
+
+Located in CPU's node:
+
+- operating-points : [See: ../power/opp.txt]
+
+Example [safe]
+--------------
+
+cpus {
+ cpu@0 {
+ /* kHz uV */
+ operating-points = <1500000 0
+ 1200000 0
+ 800000 0
+ 500000 0>;
+ };
+};
+
+Dynamic Voltage and Frequency Scaling (DVFS)
+--------------------------------------------
+
+This requires the ST CPUFreq driver to supply 'process' and 'version' info.
+
+Located in CPU's node:
+
+- operating-points-v2 : [See ../power/opp.txt]
+
+Example [unsafe]
+----------------
+
+cpus {
+ cpu@0 {
+ operating-points-v2 = <&cpu0_opp_table>;
+ };
+};
+
+cpu0_opp_table: opp_table {
+ compatible = "operating-points-v2";
+
+ /* ############################################################### */
+ /* # WARNING: Do not attempt to copy/replicate these nodes, # */
+ /* # they are only to be supplied by the bootloader !!! # */
+ /* ############################################################### */
+ opp0 {
+ /* Major Minor Substrate */
+ /* 2 all all */
+ opp-supported-hw = <0x00000004 0xffffffff 0xffffffff>;
+ opp-hz = /bits/ 64 <1500000000>;
+ clock-latency-ns = <10000000>;
+
+ opp-microvolt-pcode0 = <1200000>;
+ opp-microvolt-pcode1 = <1200000>;
+ opp-microvolt-pcode2 = <1200000>;
+ opp-microvolt-pcode3 = <1200000>;
+ opp-microvolt-pcode4 = <1170000>;
+ opp-microvolt-pcode5 = <1140000>;
+ opp-microvolt-pcode6 = <1100000>;
+ opp-microvolt-pcode7 = <1070000>;
+ };
+
+ opp1 {
+ /* Major Minor Substrate */
+ /* all all all */
+ opp-supported-hw = <0xffffffff 0xffffffff 0xffffffff>;
+ opp-hz = /bits/ 64 <1200000000>;
+ clock-latency-ns = <10000000>;
+
+ opp-microvolt-pcode0 = <1110000>;
+ opp-microvolt-pcode1 = <1150000>;
+ opp-microvolt-pcode2 = <1100000>;
+ opp-microvolt-pcode3 = <1080000>;
+ opp-microvolt-pcode4 = <1040000>;
+ opp-microvolt-pcode5 = <1020000>;
+ opp-microvolt-pcode6 = <980000>;
+ opp-microvolt-pcode7 = <930000>;
+ };
+};