Re: [PATCH v2] PM / devfreq: Add support for QCOM devfreq firmware
From: Rob Herring <robh@kernel.org>
Date: 2018-05-22 18:08:42
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linux-pm, lkml
On Fri, May 18, 2018 at 12:52:40AM -0700, Saravana Kannan wrote:
quoted hunk ↗ jump to hunk
The firmware present in some QCOM chipsets offloads the steps necessary for changing the frequency of some devices (Eg: L3). This driver implements the devfreq interface for this firmware so that various governors could be used to scale the frequency of these devices. Each client (say cluster 0 and cluster 1) that wants to vote for a particular device's frequency (say, L3 frequency) is represented as a separate voter device (qcom,devfreq-fw-voter) that's a child of the firmware device (qcom,devfreq-fw). Signed-off-by: Saravana Kannan <redacted> --- .../bindings/devfreq/devfreq-qcom-fw.txt | 41 +++ drivers/devfreq/Kconfig | 14 + drivers/devfreq/Makefile | 1 + drivers/devfreq/devfreq_qcom_fw.c | 330 +++++++++++++++++++++ 4 files changed, 386 insertions(+) create mode 100644 Documentation/devicetree/bindings/devfreq/devfreq-qcom-fw.txt create mode 100644 drivers/devfreq/devfreq_qcom_fw.cdiff --git a/Documentation/devicetree/bindings/devfreq/devfreq-qcom-fw.txt b/Documentation/devicetree/bindings/devfreq/devfreq-qcom-fw.txt new file mode 100644 index 0000000..f882a0b --- /dev/null +++ b/Documentation/devicetree/bindings/devfreq/devfreq-qcom-fw.txt@@ -0,0 +1,41 @@ +QCOM Devfreq firmware device + +Some Qualcomm Technologies, Inc. (QTI) chipsets have a firmware that +offloads the steps for frequency switching. It provides a table of +supported frequencies and a register to request one of the supported +freqencies. + +The qcom,devfreq-fw represents this firmware as a device. Sometimes, +multiple entities want to vote on the frequency request that is sent to the +firmware. The qcom,devfreq-fw-voter represents these voters as child +devices of the corresponding qcom,devfreq-fw device. + +Required properties: +- compatible: Must be "qcom,devfreq-fw" or "qcom,devfreq-fw-voter"
No versions of firmware?
+Only for qcom,devfreq-fw: +- reg: Pairs of physical base addresses and region sizes of + memory mapped registers.
Registers? Is this firmware or h/w block?
+- reg-names: Names of the bases for the above registers.
+ Required register regions are:
+ - "en-base": address of register to check if the
+ firmware is enabled.
+ - "ftbl-base": address region for the frequency
+ table.
+ - "perf-base": address of register to request a
+ frequency.
+
+Example:
+
+ qcom,devfreq-l3 {
+ compatible = "qcom,devfreq-fw";
+ reg-names = "en-base", "ftbl-base", "perf-base";
+ reg = <0x18321000 0x4>, <0x18321110 0x600>, <0x18321920 0x4>;
+
+ qcom,cpu0-l3 {
+ compatible = "qcom,devfreq-fw-voter";There's no point in these nodes. They don't have any properties or resources.
+ };
+
+ qcom,cpu4-l3 {
+ compatible = "qcom,devfreq-fw-voter";
+ };
+ };