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+NXP i.MX System Controller Firmware (SCFW)
+--------------------------------------------------------------------
+
+The System Controller Firmware (SCFW) is a low-level system function
+which runs on a dedicated Cortex-M core to provide power, clock, and
+resource management. It exists on some i.MX8 processors. e.g. i.MX8QM
+(QM, QP), and i.MX8QX (QXP, DX).
+
+The AP communicates with the SC using a multi-ported MU module found
+in the LSIO subsystem. The current definition of this MU module provides
+5 remote AP connections to the SC to support up to 5 execution environments
+(TZ, HV, standard Linux, etc.). The SC side of this MU module interfaces
+with the LSIO DSC IP bus. The SC firmware will communicate with this MU
+using the MSI bus.
+
+System Controller Device Node:
+============================================================
+
+The scu node with the following properties shall be under the /firmware/ node.
+
+Required properties:
+-------------------
+- compatible: should be "fsl,imx-scu".
+- mbox-names: should include "tx0", "tx1", "tx2", "tx3",
+ "rx0", "rx1", "rx2", "rx3".
+- mboxes: List of phandle of 4 MU channels for tx and 4 MU channels
+ for rx. All 8 MU channels must be in the same MU instance.
+ Cross instances are not allowed. The MU instance can only
+ be one of LSIO MU0~M4 for imx8qxp and imx8qm. Users need
+ to make sure use the one which is not conflict with other
+ execution environments. e.g. ATF.
+ Note:
+ Channel 0 must be "tx0" or "rx0".
+ Channel 1 must be "tx1" or "rx1".
+ Channel 2 must be "tx2" or "rx2".
+ Channel 3 must be "tx3" or "rx3".
+ e.g.
+ mboxes = <&lsio_mu1 0 0
+ &lsio_mu1 0 1
+ &lsio_mu1 0 2
+ &lsio_mu1 0 3
+ &lsio_mu1 1 0
+ &lsio_mu1 1 1
+ &lsio_mu1 1 2
+ &lsio_mu1 1 3>;
+ See Documentation/devicetree/bindings/mailbox/fsl,mu.txt
+ for detailed mailbox binding.
+
+i.MX SCU Client Device Node:
+============================================================
+
+Client nodes are maintained as children of the relevant IMX-SCU device node.
+
+Power domain bindings based on SCU Message Protocol
+------------------------------------------------------------
+
+This binding for the SCU power domain providers uses the generic power
+domain binding[2].
+
+Required properties:
+- compatible: Should be "fsl,scu-pd".
+- #address-cells: Should be 1.
+- #size-cells: Should be 0.
+
+Required properties for power domain sub nodes:
+- #power-domain-cells: Must be 0.
+
+Optional Properties:
+- reg: Resource ID of this power domain.
+ No exist means uncontrollable by user.
+ See detailed Resource ID list from:
+ include/dt-bindings/power/imx-rsrc.h
+- power-domains: phandle pointing to the parent power domain.
+
+Clock bindings based on SCU Message Protocol
+------------------------------------------------------------
+
+This binding uses the common clock binding[1].
+
+Required properties:
+- compatible: Should be "fsl,imx8qxp-clock".
+- #clock-cells: Should be 1. Contains the Clock ID value.
+- clocks: List of clock specifiers, must contain an entry for
+ each required entry in clock-names
+- clock-names: Should include entries "xtal_32KHz", "xtal_24MHz"
+
+The clock consumer should specify the desired clock by having the clock
+ID in its "clocks" phandle cell.
+
+See the full list of clock IDs from:
+include/dt-bindings/clock/imx8qxp-clock.h
+
+Pinctrl bindings based on SCU Message Protocol
+------------------------------------------------------------
+
+This binding uses the i.MX common pinctrl binding[3].
+
+Required properties:
+- compatible: Should be "fsl,imx8qxp-iomuxc".
+
+Required properties for Pinctrl sub nodes:
+- fsl,pins: Each entry consists of 3 integers which represents
+ the mux and config setting for one pin. The first 2
+ integers <pin_id mux_mode> are specified using a
+ PIN_FUNC_ID macro, which can be found in
+ <dt-bindings/pinctrl/pads-imx8qxp.h>.
+ The last integer CONFIG is the pad setting value like
+ pull-up on this pin.
+
+ Please refer to i.MX8QXP Reference Manual for detailed
+ CONFIG settings.
+
+[1] Documentation/devicetree/bindings/clock/clock-bindings.txt
+[2] Documentation/devicetree/bindings/power/power_domain.txt
+[3] Documentation/devicetree/bindings/pinctrl/fsl,imx-pinctrl.txt
+
+Example (imx8qxp):
+-------------
+lsio_mu1: mailbox@5d1c0000 {
+ ...
+ #mbox-cells = <2>;
+};
+
+firmware {
+ scu {
+ compatible = "fsl,imx-scu";
+ mbox-names = "tx0", "tx1", "tx2", "tx3",
+ "rx0", "rx1", "rx2", "rx3";
+ mboxes = <&lsio_mu1 0 0
+ &lsio_mu1 0 1
+ &lsio_mu1 0 2
+ &lsio_mu1 0 3
+ &lsio_mu1 1 0
+ &lsio_mu1 1 1
+ &lsio_mu1 1 2
+ &lsio_mu1 1 3>;
+
+ clk: clk {
+ compatible = "fsl,imx8qxp-clk";
+ #clock-cells = <1>;
+ };
+
+ iomuxc {
+ compatible = "fsl,imx8qxp-iomuxc";
+
+ pinctrl_lpuart0: lpuart0grp {
+ fsl,pins = <
+ SC_P_UART0_RX_ADMA_UART0_RX 0x06000020
+ SC_P_UART0_TX_ADMA_UART0_TX 0x06000020
+ >;
+ };
+ ...
+ };
+
+ imx8qx-pm {
+ compatible = "fsl,scu-pd";
+ #address-cells = <1>;
+ #size-cells = <0>;
+
+ pd_dma: dma-power-domain {
+ #power-domain-cells = <0>;
+
+ pd_dma_lpuart0: dma-lpuart0@57 {
+ reg = <SC_R_UART_0>;
+ #power-domain-cells = <0>;
+ power-domains = <&pd_dma>;
+ };
+ ...
+ };
+ ...
+ };
+ };
+};
+
+serial@5a060000 {
+ ...
+ pinctrl-names = "default";
+ pinctrl-0 = <&pinctrl_lpuart0>;
+ clocks = <&clk IMX8QXP_UART0_CLK>,
+ <&clk IMX8QXP_UART0_IPG_CLK>;
+ clock-names = "per", "ipg";
+ power-domains = <&pd_dma_lpuart0>;
+};