On Wed, Nov 09, 2016 at 06:36:21PM +0530, Laxman Dewangan wrote:
> NVIDIA Tegra124 and later SoCs support the multi-voltage level and
> low power state of some of its IO pads. The IO pads can work in
> the voltage of the 1.8V and 3.3V of IO voltage from IO power rail
> sources. When IO interfaces are not used then IO pads can be
> configure in low power state to reduce the power consumption from
> that IO pads.
>
> On Tegra124, the voltage level of IO power rail source is auto
> detected by hardware(SoC) and hence it is only require to configure
> in low power mode if IO pads are not used.
>
> On T210 onwards, the auto-detection of voltage level from IO power
> rail is removed from SoC and hence SW need to configure the PMC
> register explicitly to set proper voltage in IO pads based on
> IO rail power source voltage.
>
> Add DT binding document for detailing the DT properties for
> configuring IO pads voltage levels and its power state.
>
> Signed-off-by: Laxman Dewangan <ldewangan@xxxxxxxxxx>
>
> ---
> Changes from V1:
> The DT binding document is modified to explain the regulator handle
> for different IOs and how can it be passed from the DT.
> ---
> .../bindings/pinctrl/nvidia,tegra-io-pad.txt | 126 +++++++++++++++++++++
> 1 file changed, 126 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/pinctrl/nvidia,tegra-io-pad.txt
>
> diff --git a/Documentation/devicetree/bindings/pinctrl/nvidia,tegra-io-pad.txt b/Documentation/devicetree/bindings/pinctrl/nvidia,tegra-io-pad.txt
> new file mode 100644
> index 0000000..6ca961f
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/pinctrl/nvidia,tegra-io-pad.txt
> @@ -0,0 +1,126 @@
> +NVIDIA Tegra PMC IO pad controller
> +
> +NVIDIA Tegra124 and later SoCs support the multi-voltage level and
> +low power state of some of its IO pads. When IO interface are not
> +used then IO pads can be configure in low power state to reduce
> +the power from that IO pads. The IO pads can work in the voltage
> +of the 1.8V and 3.3V of IO voltage from power rail sources.
> +
> +On Tegra124, the voltage of IO power rail source is auto detected by
> +SoC and hence it is only require to configure in low power mode if
> +IO pads are not used.
> +
> +On T210 onwards, the HW based auto-detection for IO voltage is removed
> +and hence SW need to configure the PMC register explicitly, to set proper
> +voltage in IO pads, based on IO rail power source voltage.
> +
> +The voltage configurations and low power state of IO pads should be done
> +in boot if it is not going to change other wise dynamically based on IO
> +rail voltage on that IO pads and usage of IO pads
s/other wise/otherwise/
The end of the sentence is not clear and missing a period.
> +
> +The DT property of the io pads must be under the node of pmc i.e.
> +pmc@7000e400 for Tegra124 onwards.
s/io/IO/
> +
> +Please refer to <pinctrl-bindings.txt> in this directory for details of the
> +common pinctrl bindings used by client devices, including the meaning of the
> +phrase "pin configuration node".
> +
> +Tegra's pin configuration nodes act as a container for an arbitrary number of
> +subnodes. Each of these subnodes represents some desired configuration for an
> +IO pads, or a list of IO pads. This configuration can include the voltage and
> +power enable/disable control
> +
> +The name of each subnode is not important; all subnodes should be enumerated
> +and processed purely based on their content. Each subnode only affects those
> +parameters that are explicitly listed. Unspecified is represented as an absent
> +property,
> +
> +See the TRM to determine which properties and values apply to each IO pads.
> +
> +Required subnode-properties:
> +==========================
> +- pins : An array of strings. Each string contains the name of an IO pads. Valid
> + values for these names are listed below.
> +
> +Optional subnode-properties:
> +==========================
> +Following properties are supported from generic pin configuration explained
> +in <dt-bindings/pinctrl/pinctrl-binding.txt>.
> +low-power-enable: enable low power mode.
> +low-power-disable: disable low power mode.
> +
> +Valid values for pin for T124 are:
> + audio, bb, cam, comp, csia, csib, csie, dsi, dsib, dsic, dsid, hdmi,
> + hsic, hv, lvds, mipi-bias, nand, pex-bias, pex-clk1, pex-clk2,
> + pex-ctrl, sdmmc1, sdmmc3, sdmmc4, sys-ddc, uart, usb0, usb1, usb2,
> + usb-bias
> +
> +Valid values for pin for T210 are:
> + audio, audio-hv, cam, csia, csib, csic, csid, csie, csif,
> + dbg, debug-nonao, dmic, dp, dsi, dsib, dsic, dsid, emmc, emmc2,
> + gpio, hdmi, hsic, lvds, mipi-bias, pex-bias, pex-clk1, pex-clk2,
> + pex-ctrl, sdmmc1, sdmmc3, spi, spi-hv, uart, usb-bias, usb0,
> + usb1, usb2, usb3.
> +
> +To find out the IO rail voltage for setting the voltage of IO pad by SW,
> +the regulator supply handle must provided from the DT and it is explained
> +in the regulator DT binding document
> + <devicetree/bindings/regulator/regulator.txt>.
> +For example, for GPIO rail the supply name is vddio-gpio and regulator
> +handle is supplied from DT as
> + vddio-gpio-supply = <®ulator_xyz>;
> +
> +For T210, following IO pads support the 1.8V/3.3V and the corresponding
> +io voltage pin names are as follows:
> + audio -> vddio-audio
> + audio-hv -> vddio-audio-hv
> + cam ->vddio-cam
> + dbg -> vddio-dbg
> + dmic -> vddio-dmic
> + gpio -> vddio-gpio
> + pex-ctrl -> vddio-pex-ctrl
> + sdmmc1 -> vddio-sdmmc1
> + sdmmc3 -> vddio-sdmmc3
> + spi -> vddio-spi
> + spi-hv -> vddio-spi-hv
> + uart -> vddio-uart
> +
> +Example:
> + i2c@7000d000 {
> + pmic@3c {
> + regulators {
> + vddio_sdmmc1: ldo2 {
> + /* Regulator entries for LDO2 */
> + };
> +
> + vdd_cam: ldo3 {
> + /* Regulator entries for LDO3 */
> + };
> + };
> + };
> + };
> +
> + pmc@7000e400 {
> + vddio-cam = <&vdd_cam>;
Missing -supply.
> + vddio-sdmmc1-supply = <&vddio_sdmmc1>;
> +
> + pinctrl-names = "default";
> + pinctrl-0 = <&tegra_io_pad_volt_default>;
> + tegra_io_pad_volt_default: common {
> + audio-hv {
> + pins = "audio-hv";
> + low-power-disable;
> + };
> +
> + gpio {
> + pins = "gpio";
> + low-power-disable;
> + };
> +
> + audio {
> + pins = "audio", "dmic", "sdmmc3";
What's the purpose of grouping these?
> + low-power-enable;
> + };
> + };
> +
> + };
> --
> 2.1.4
>
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