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riscv,machine-timer

Vendor: RISC-V Foundation

Description

RISC-V Machine timer

Properties

Node specific properties

Deprecated node specific properties

Base properties

Properties not inherited from the base binding file.

Name

Type

Details

clk-divider

int

 
clk-divider specifies the division ratio to the CPU frequency that
clock used by machine timer.
This property supports the case that the machine timer and CPU use
different clock sources.
This configuration is used sometimes for such as low power consumption.

For example, the CPU clock frequency is 108MHz, and the machine timer
uses 27MHz, which is the CPU clock divided by 4.
In this case, the CPU clock frequency is defined in the CPU node
as follows

   clock-frequency = <108000000>;

This property takes exponent of the power of 2.
The relationship with the frequency division ratio is as
following equation.

   division_ratio = 2^n
   n = log_2(division_ratio)

Setting clk-divider to 2 specifies the machine timer uses the clock
that CPU clock frequency divided by (2^2=)4, or 27MHz.

Devision ratio constants can be found in the
dt-bindings/timer/nuclei-machine-timer.h header file.

Deprecated properties not inherited from the base binding file.

(None)

Properties inherited from the base binding file, which defines common properties that may be set on many nodes. Not all of these may apply to the “riscv,machine-timer” compatible.

Name

Type

Details

status

string

 
indicates the operational status of a device

Legal values: 'ok', 'okay', 'disabled', 'reserved', 'fail', 'fail-sss'

See Important properties for more information.

compatible

string-array

 
compatible strings

This property is required.

See Important properties for more information.

reg

array

 
register space

See Important properties for more information.

reg-names

string-array

 
name of each register space

interrupts

array

 
interrupts for device

See Important properties for more information.

interrupts-extended

compound

 
extended interrupt specifier for device

interrupt-names

string-array

 
name of each interrupt

interrupt-parent

phandle

 
phandle to interrupt controller node

label

string

 
Human readable string describing the device (used as device_get_binding() argument)

See Important properties for more information.

clocks

phandle-array

 
Clock gate information

clock-names

string-array

 
name of each clock

#address-cells

int

 
number of address cells in reg property

#size-cells

int

 
number of size cells in reg property

dmas

phandle-array

 
DMA channels specifiers

dma-names

string-array

 
Provided names of DMA channel specifiers

io-channels

phandle-array

 
IO channels specifiers

io-channel-names

string-array

 
Provided names of IO channel specifiers

mboxes

phandle-array

 
mailbox / IPM channels specifiers

mbox-names

string-array

 
Provided names of mailbox / IPM channel specifiers

wakeup-source

boolean

 
Property to identify that a device can be used as wake up source.

When this property is provided a specific flag is set into the
device that tells the system that the device is capable of
wake up the system.

Wake up capable devices are disabled (interruptions will not wake up
the system) by default but they can be enabled at runtime if necessary.

power-domain

phandle

 
Power domain the device belongs to.

The device will be notified when the power domain it belongs to is either
suspended or resumed.