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In some of NVIDIA Tegra's platform, PWM controller is used to control the PWM controlled regulators. PWM signal is connected to the VID pin of the regulator where duty cycle of PWM signal decide the voltage level of the regulator output. When system enters suspend, some PWM client/slave regulator devices require the PWM output to be tristated. Add DT binding details to provide the pin configuration state from PWM and pinctrl DT node in suspend and active state of the system. Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com> Acked-by: Jon Hunter <jonathanh@nvidia.com> Acked-by: Rob Herring <robh@kernel.org> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
77 lines
2.6 KiB
Plaintext
77 lines
2.6 KiB
Plaintext
Tegra SoC PWFM controller
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Required properties:
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- compatible: Must be:
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- "nvidia,tegra20-pwm": for Tegra20
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- "nvidia,tegra30-pwm", "nvidia,tegra20-pwm": for Tegra30
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- "nvidia,tegra114-pwm", "nvidia,tegra20-pwm": for Tegra114
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- "nvidia,tegra124-pwm", "nvidia,tegra20-pwm": for Tegra124
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- "nvidia,tegra132-pwm", "nvidia,tegra20-pwm": for Tegra132
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- "nvidia,tegra210-pwm", "nvidia,tegra20-pwm": for Tegra210
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- "nvidia,tegra186-pwm": for Tegra186
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- reg: physical base address and length of the controller's registers
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- #pwm-cells: should be 2. See pwm.txt in this directory for a description of
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the cells format.
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- clocks: Must contain one entry, for the module clock.
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See ../clocks/clock-bindings.txt for details.
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- resets: Must contain an entry for each entry in reset-names.
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See ../reset/reset.txt for details.
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- reset-names: Must include the following entries:
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- pwm
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Optional properties:
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============================
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In some of the interface like PWM based regulator device, it is required
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to configure the pins differently in different states, especially in suspend
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state of the system. The configuration of pin is provided via the pinctrl
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DT node as detailed in the pinctrl DT binding document
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Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt
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The PWM node will have following optional properties.
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pinctrl-names: Pin state names. Must be "default" and "sleep".
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pinctrl-0: phandle for the default/active state of pin configurations.
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pinctrl-1: phandle for the sleep state of pin configurations.
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Example:
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pwm: pwm@7000a000 {
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compatible = "nvidia,tegra20-pwm";
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reg = <0x7000a000 0x100>;
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#pwm-cells = <2>;
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clocks = <&tegra_car 17>;
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resets = <&tegra_car 17>;
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reset-names = "pwm";
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};
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Example with the pin configuration for suspend and resume:
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=========================================================
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Suppose pin PE7 (On Tegra210) interfaced with the regulator device and
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it requires PWM output to be tristated when system enters suspend.
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Following will be DT binding to achieve this:
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#include <dt-bindings/pinctrl/pinctrl-tegra.h>
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pinmux@700008d4 {
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pwm_active_state: pwm_active_state {
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pe7 {
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nvidia,pins = "pe7";
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nvidia,tristate = <TEGRA_PIN_DISABLE>;
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};
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};
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pwm_sleep_state: pwm_sleep_state {
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pe7 {
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nvidia,pins = "pe7";
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nvidia,tristate = <TEGRA_PIN_ENABLE>;
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};
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};
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};
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pwm@7000a000 {
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/* Mandatory PWM properties */
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pinctrl-names = "default", "sleep";
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pinctrl-0 = <&pwm_active_state>;
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pinctrl-1 = <&pwm_sleep_state>;
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};
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