xref: /kernel/linux/linux-6.6/Documentation/devicetree/bindings/reset/ti-syscon-reset.txt

TI SysCon Reset Controller
=======================

Almost all SoCs have hardware modules that require reset control in addition
to clock and power control for their functionality. The reset control is
typically provided by means of memory-mapped I/O registers. These registers are
sometimes a part of a larger register space region implementing various
functionalities. This register range is best represented as a syscon node to
allow multiple entities to access their relevant registers in the common
register space.

A SysCon Reset Controller node defines a device that uses a syscon node
and provides reset management functionality for various hardware modules
present on the SoC.

SysCon Reset Controller Node
============================
Each of the reset provider/controller nodes should be a child of a syscon
node and have the following properties.

Required properties:
--------------------
 - compatible		: Should be,
			    "ti,k2e-pscrst"
			    "ti,k2l-pscrst"
			    "ti,k2hk-pscrst"
			    "ti,syscon-reset"
 - #reset-cells		: Should be 1. Please see the reset consumer node below
			  for usage details
 - ti,reset-bits	: Contains the reset control register information
			  Should contain 7 cells for each reset exposed to
			  consumers, defined as:
			    Cell #1 : offset of the reset assert control
			              register from the syscon register base
			    Cell #2 : bit position of the reset in the reset
			              assert control register
			    Cell #3 : offset of the reset deassert control
			              register from the syscon register base
			    Cell #4 : bit position of the reset in the reset
			              deassert control register
			    Cell #5 : offset of the reset status register
			              from the syscon register base
			    Cell #6 : bit position of the reset in the
			              reset status register
			    Cell #7 : Flags used to control reset behavior,
			              available flags defined in the DT include
			              file <dt-bindings/reset/ti-syscon.h>

SysCon Reset Consumer Nodes
===========================
Each of the reset consumer nodes should have the following properties,
in addition to their own properties.

Required properties:
--------------------
 - resets	: A phandle to the reset controller node and an index number
		  to a reset specifier as defined above.

Please also refer to Documentation/devicetree/bindings/reset/reset.txt for
common reset controller usage by consumers.

Example:
--------
The following example demonstrates a syscon node, the reset controller node
using the syscon node, and a consumer (a DSP device) on the TI Keystone 2
66AK2E SoC.

/ {
	soc {
		psc: power-sleep-controller@2350000 {
			compatible = "syscon", "simple-mfd";
			reg = <0x02350000 0x1000>;

			pscrst: reset-controller {
				compatible = "ti,k2e-pscrst", "ti,syscon-reset";
				#reset-cells = <1>;

				ti,reset-bits = <
					0xa3c 8 0xa3c 8 0x83c 8 (ASSERT_CLEAR | DEASSERT_SET   | STATUS_CLEAR) /* 0: dsp0 */
					0xa40 5 0xa44 3 0     0 (ASSERT_SET   | DEASSERT_CLEAR | STATUS_NONE)  /* 1: example */
				>;
			};
		};

		dsp0: dsp0 {
			...
			resets = <&pscrst 0>;
			...
		};
	};
};