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authorAndrew F. Davis <afd@ti.com>2016-06-27 12:12:16 -0500
committerPhilipp Zabel <p.zabel@pengutronix.de>2016-06-29 23:39:10 +0200
commita3828519c39aa9c85bae14bad2572d12dc0d1da6 (patch)
treed5a7e1c82ae46b4f803ffc13f2974e441d0b7ae9 /Documentation
parentab52b599c197b5e50ad918f8084673d9b4caed83 (diff)
Documentation: dt: reset: Add TI syscon reset binding
Add TI syscon reset controller binding. This will hook to the reset framework and use syscon/regmap to set reset bits. This allows reset control of individual SoC subsytems and devices with memory-mapped reset registers in a common register memory space. Signed-off-by: Andrew F. Davis <afd@ti.com> Signed-off-by: Suman Anna <s-anna@ti.com> Acked-by: Rob Herring <robh@kernel.org> Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
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+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,
+ availible 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
+Edison SoC.
+
+/ {
+ soc {
+ psc: power-sleep-controller@02350000 {
+ compatible = "syscon", "simple-mfd";
+ reg = <0x02350000 0x1000>;
+
+ pscrst: psc-reset {
+ compatible = "ti,k2e-pscrst", "ti,syscon-reset";
+ #reset-cells = <1>;
+
+ ti,reset-bits = <
+ 0xa3c 8 0xa3c 8 0x83c 8 (ASSERT_SET|DEASSERT_CLEAR|STATUS_SET) /* 0: pcrst-dsp0 */
+ 0xa40 5 0xa44 3 0 0 (ASSERT_SET|DEASSERT_CLEAR|STATUS_NONE) /* 1: pcrst-example */
+ >;
+ };
+ };
+
+ dsp0: dsp0 {
+ ...
+ resets = <&pscrst 0>;
+ ...
+ };
+ };
+};