pinctrl: Add Tegra194 pinctrl DT bindings

Add binding doc for Tegra 194 pinctrl driver.
Signed-off-by: Krishna Yarlagadda <kyarlagadda@nvidia.com>
Tested-by: Vidya Sagar <vidyas@nvidia.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

Documentation/devicetree/bindings/pinctrl/nvidia,tegra194-pinmux.txt

+NVIDIA Tegra194 pinmux controller
+
+Required properties:
+- compatible: "nvidia,tegra194-pinmux"
+- reg: Should contain a list of base address and size pairs for:
+  - first entry: The APB_MISC_GP_*_PADCTRL registers (pad control)
+  - second entry: The PINMUX_AUX_* registers (pinmux)
+
+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 a
+pin, a group, or a list of pins or groups. This configuration can include the
+mux function to select on those pin(s)/group(s), and various pin configuration
+parameters, such as pull-up, tristate, drive strength, etc.
+
+See the TRM to determine which properties and values apply to each pin/group.
+Macro values for property values are defined in
+include/dt-binding/pinctrl/pinctrl-tegra.h.
+
+Required subnode-properties:
+- nvidia,pins : An array of strings. Each string contains the name of a pin or
+    group. Valid values for these names are listed below.
+
+Optional subnode-properties:
+- nvidia,function: A string containing the name of the function to mux to the
+    pin or group.
+- nvidia,pull: Integer, representing the pull-down/up to apply to the pin.
+    0: none, 1: down, 2: up.
+- nvidia,tristate: Integer.
+    0: drive, 1: tristate.
+- nvidia,enable-input: Integer. Enable the pin's input path.
+    enable :TEGRA_PIN_ENABLE and
+    disable or output only: TEGRA_PIN_DISABLE.
+- nvidia,open-drain: Integer.
+    enable: TEGRA_PIN_ENABLE.
+    disable: TEGRA_PIN_DISABLE.
+- nvidia,lock: Integer. Lock the pin configuration against further changes
+    until reset.
+    enable: TEGRA_PIN_ENABLE.
+    disable: TEGRA_PIN_DISABLE.
+- nvidia,io-hv: Integer. Select high-voltage receivers.
+    normal: TEGRA_PIN_DISABLE
+    high: TEGRA_PIN_ENABLE
+- nvidia,schmitt: Integer. Enables Schmitt Trigger on the input.
+    normal: TEGRA_PIN_DISABLE
+    high: TEGRA_PIN_ENABLE
+- nvidia,drive-type: Integer. Valid range 0...3.
+- nvidia,pull-down-strength: Integer. Controls drive strength. 0 is weakest.
+    The range of valid values depends on the pingroup. See "CAL_DRVDN" in the
+    Tegra TRM.
+- nvidia,pull-up-strength: Integer. Controls drive strength. 0 is weakest.
+    The range of valid values depends on the pingroup. See "CAL_DRVUP" in the
+    Tegra TRM.
+
+Valid values for pin and group names (nvidia,pin) are:
+
+    These correspond to Tegra PADCTL_* (pinmux) registers.
+
+  Mux groups:
+
+    These correspond to Tegra PADCTL_* (pinmux) registers. Any property
+    that exists in those registers may be set for the following pin names.
+
+    pex_l5_clkreq_n_pgg0, pex_l5_rst_n_pgg1
+
+  Drive groups:
+
+    These registers controls a single pin for which a mux group exists.
+    See the list above for the pin name to use when configuring the pinmux.
+
+    pex_l5_clkreq_n_pgg0, pex_l5_rst_n_pgg1
+
+Valid values for nvidia,functions are:
+
+    pe5
+
+Power Domain:
+    pex_l5_clkreq_n_pgg0 and pex_l5_rst_n_pgg1 are part of PCIE C5 power
+    partition. Client devices must enable this partition before accessing
+    these pins here.
+
+
+Example:
+
+		tegra_pinctrl: pinmux: pinmux@2430000 {
+			compatible = "nvidia,tegra194-pinmux";
+			reg = <0x2430000 0x17000
+			       0xc300000 0x4000>;
+
+			pinctrl-names = "pex_rst";
+			pinctrl-0 = <&pex_rst_c5_out_state>;
+
+			pex_rst_c5_out_state: pex_rst_c5_out {
+				pex_rst {
+					nvidia,pins = "pex_l5_rst_n_pgg1";
+					nvidia,schmitt = <TEGRA_PIN_DISABLE>;
+					nvidia,lpdr = <TEGRA_PIN_ENABLE>;
+					nvidia,enable-input = <TEGRA_PIN_DISABLE>;
+					nvidia,io-high-voltage = <TEGRA_PIN_ENABLE>;
+					nvidia,tristate = <TEGRA_PIN_DISABLE>;
+					nvidia,pull = <TEGRA_PIN_PULL_NONE>;
+				};
+			};
+		};