Re: [PATCH v5 4/8] dt-bindings: devfreq: add Exynos5422 DMC device description

From: Krzysztof Kozlowski
Date: Tue Mar 05 2019 - 06:36:11 EST

On Tue, 5 Mar 2019 at 11:19, Lukasz Luba <l.luba@xxxxxxxxxxxxxxxxxxx> wrote:
>
> The patch adds description for DT binding for a new Exynos5422 Dynamic
> Memory Controller device.
>
> Signed-off-by: Lukasz Luba <l.luba@xxxxxxxxxxxxxxxxxxx>
> ---
> .../devicetree/bindings/devfreq/exynos5422-dmc.txt | 177 +++++++++++++++++++++
> 1 file changed, 177 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/devfreq/exynos5422-dmc.txt
>
> diff --git a/Documentation/devicetree/bindings/devfreq/exynos5422-dmc.txt b/Documentation/devicetree/bindings/devfreq/exynos5422-dmc.txt
> new file mode 100644
> index 0000000..0e73e98
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/devfreq/exynos5422-dmc.txt
> @@ -0,0 +1,177 @@
> +* Exynos5422 frequency and voltage scaling for Dynamic Memory Controller device
> +
> +The Samsung Exynos5422 SoC has DMC (Dynamic Memory Controller) to which the DRAM
> +memory chips are connected. The driver is to monitor the controller in runtime
> +and switch frequency and voltage. To monitor the usage of the controller in
> +runtime, the driver uses the PPMU (Platform Performance Monitoring Unit), which
> +is able to measure the current load of the memory.
> +When 'userspace' governor is used for the driver, an application is able to
> +switch the DMC frequency.
> +
> +Required properties for DMC device for Exynos5422:
> +- compatible: Should be "samsung,exynos5422-bus".
> +- clock-names : the name of clock used by the bus, "bus".
> +- clocks : phandles for clock specified in "clock-names" property.
> +- devfreq-events : phandles for PPMU devices connected to this DMC.
> +
> +The example definition of a DMC and PPMU devices declared in DT is shown below:
> +
> + ppmu_dmc0_0: ppmu@10d00000 {
> + compatible = "samsung,exynos-ppmu";
> + reg = <0x10d00000 0x2000>;
> + clocks = <&clock CLK_PCLK_PPMU_DREX0_0>;
> + clock-names = "ppmu";
> + status = "okay";
> + events {
> + ppmu_event_dmc0_0: ppmu-event3-dmc0_0 {
> + event-name = "ppmu-event3-dmc0_0";
> + };
> + };
> + };
> +
> +
> + ppmu_dmc0_1: ppmu@10d10000 {
> + compatible = "samsung,exynos-ppmu";
> + reg = <0x10d10000 0x2000>;
> + clocks = <&clock CLK_PCLK_PPMU_DREX0_1>;
> + clock-names = "ppmu";
> + status = "okay";
> + events {
> + ppmu_event_dmc0_1: ppmu-event3-dmc0_1 {
> + event-name = "ppmu-event3-dmc0_1";
> + };
> + };
> + };
> +
> + ppmu_dmc1_0: ppmu@10d10000 {
> + compatible = "samsung,exynos-ppmu";
> + reg = <0x10d60000 0x2000>;
> + clocks = <&clock CLK_PCLK_PPMU_DREX1_0>;
> + clock-names = "ppmu";
> + status = "okay";
> + events {
> + ppmu_event_dmc1_0: ppmu-event3-dmc1_0 {
> + event-name = "ppmu-event3-dmc1_0";
> + };
> + };
> + };
> +
> + ppmu_dmc1_1: ppmu@10d70000 {
> + compatible = "samsung,exynos-ppmu";
> + reg = <0x10d70000 0x2000>;
> + clocks = <&clock CLK_PCLK_PPMU_DREX1_1>;
> + clock-names = "ppmu";
> + status = "okay";
> + events {
> + ppmu_event_dmc1_1: ppmu-event3-dmc1_1 {
> + event-name = "ppmu-event3-dmc1_1";
> + };
> + };
> + };
> +
> + dmc: memory-controller@10c20000 {
> + compatible = "samsung,exynos5422-dmc";
> + reg = <0x10c20000 0x10000>, <0x10c30000 0x10000>,
> + <0x10000000 0x1000>;
> + clocks = <&clock CLK_FOUT_SPLL>,
> + <&clock CLK_MOUT_SCLK_SPLL>,
> + <&clock CLK_FF_DOUT_SPLL2>,
> + <&clock CLK_FOUT_BPLL>,
> + <&clock CLK_MOUT_BPLL>,
> + <&clock CLK_SCLK_BPLL>,
> + <&clock CLK_MOUT_MX_MSPLL_CCORE>,
> + <&clock CLK_MOUT_MX_MSPLL_CCORE_PHY>,
> + <&clock CLK_MOUT_MCLK_CDREX>,
> + <&clock CLK_DOUT_CLK2X_PHY0>,
> + <&clock CLK_CLKM_PHY0>,
> + <&clock CLK_CLKM_PHY1>,
> + <&clock CLK_CDREX_PAUSE>,
> + <&clock CLK_CDREX_TIMING_SET>;
> + clock-names = "fout_spll",
> + "mout_sclk_spll",
> + "ff_dout_spll2",
> + "fout_bpll",
> + "mout_bpll",
> + "sclk_bpll",
> + "mout_mx_mspll_ccore",
> + "mout_mx_mspll_ccore_phy",
> + "mout_mclk_cdrex",
> + "dout_clk2x_phy0",
> + "clkm_phy0",
> + "clkm_phy1",
> + "clk_cdrex_pause",
> + "clk_cdrex_timing_set";
> + status = "okay";
> + operating-points-v2 = <&dmc_opp_table>;
> + devfreq-events = <&ppmu_dmc0_0>, <&ppmu_dmc0_1>,
> + <&ppmu_dmc1_0>, <&ppmu_dmc1_1>;
> + };
> +
> +The needed timings of DRAM memory are stored in dedicated nodes.
> +There are two nodes with regular timings and for bypass mode.
> +
> + dmc_bypass_mode: bypass_mode {
> + compatible = "samsung,dmc-bypass-mode";

This looks like an example, not bindings.

> +
> + freq-hz = <400000000>;
> + volt-uv = <887500>;

-microvolt
Documentation/devicetree/bindings/property-units.txt

> + dram-timing-row = <0x365a9713>;
> + dram-timing-data = <0x4740085e>;
> + dram-timing-power = <0x543a0446>;
> + };
> +
> + dram_timing: timing {
> + compatible = "samsung,dram-timing";

Probably you should use timings from Documentation/devicetree/bindings/lpddr2/
If not, all the fields below should be described.

All these bindings (memory-controller, timings) look like description
of memory controller so maybe they should go into
Documentation/devicetree/bindings/memory-controllers ?

Best regards,
Krzysztof

> +
> + dram-timing-names = "165MHz", "206MHz", "275MHz", "413MHz",
> + "543MHz", "633MHz", "728MHz", "825MHz";
> + dram-timing-row = <0x11223185>, <0x112331C6>, <0x12244287>,
> + <0x1B35538A>, <0x244764CD>, <0x2A48758F>,
> + <0x30598651>, <0x365A9713>;
> + dram-timing-data = <0x2720085E>, <0x2720085E>, <0x2720085E>,
> + <0x2720085E>, <0x3730085E>, <0x3730085E>,
> + <0x3730085E>, <0x4740085E>;
> + dram-timing-power = <0x140C0225>, <0x180F0225>, <0x1C140225>,
> + <0x2C1D0225>, <0x38270335>, <0x402D0335>,
> + <0x4C330336>, <0x543A0446>;
> + };
> +
> +The frequencies supported by the DMC are stored in OPP table v2.
> +
> + dmc_opp_table: opp_table2 {
> + compatible = "operating-points-v2";
> +
> + opp00 {
> + opp-hz = /bits/ 64 <165000000>;
> + opp-microvolt = <875000>;
> + };
> + opp01 {
> + opp-hz = /bits/ 64 <206000000>;
> + opp-microvolt = <875000>;
> + };
> + opp02 {
> + opp-hz = /bits/ 64 <275000000>;
> + opp-microvolt = <875000>;
> + };
> + opp03 {
> + opp-hz = /bits/ 64 <413000000>;
> + opp-microvolt = <887500>;
> + };
> + opp04 {
> + opp-hz = /bits/ 64 <543000000>;
> + opp-microvolt = <937500>;
> + };
> + opp05 {
> + opp-hz = /bits/ 64 <633000000>;
> + opp-microvolt = <1012500>;
> + };
> + opp06 {
> + opp-hz = /bits/ 64 <728000000>;
> + opp-microvolt = <1037500>;
> + };
> + opp07 {
> + opp-hz = /bits/ 64 <825000000>;
> + opp-microvolt = <1050000>;
> + };
> + };
> +
> --
> 2.7.4
>