On Fri, May 18, 2018 at 12:52:40AM -0700, Saravana Kannan wrote:
> 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 <[email protected]>
> ---
> .../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.c
>
> diff --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";
> + };
> + };
