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
|
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>;
|
...
|
};
|
};
|
};
|
