pwm-clock
Vendor: Generic or vendor-independent
Note
An implementation of a driver matching this compatible is available in drivers/clock_control/clock_control_pwm.c.
Description
An external clock signal driven by a PWM pin.
The devicetree must define a clock node:
pwmclock: pwmclock {
status = "okay";
compatible = "pwm-clock";
#clock-cells = <1>;
pwms = <&pwm_ccu40 2 PWM_HZ(1000000) PWM_POLARITY_NORMAL>;
};
This will create a device node with a clock-controller
API. Internally the device node will use PWM API to start the
clock signals at 1MHz. Note that the PWM_HZ() macro converts the
frequency to time (nanoseconds units). This may result in rounding
errors if the clock frequency is not an integer number of nanoseconds.
The clock frequency can be explicitly set using the clock-frequency
property.
The PWM node may need to be properly configured to generate
the target period (i.e. using prescaler options). See the documentation
for the target PWM driver.
Properties
Properties not inherited from the base binding file.
Name |
Type |
Details |
|---|---|---|
|
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This property is required. |
|
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Exact output frequency, in case the PWM period is not exact
but was rounded to nanoseconds. This property is optional.
|
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Optional blocking delay in micro seconds to make sure that the PWM clock has started after returning from clock_control_on().
|
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|
Number of items to expect in a Clock specifier
This property is required. Constant value: |
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 “pwm-clock” compatible.
Name |
Type |
Details |
|---|---|---|
|
|
indicates the operational status of a device
Legal values: See Important properties for more information. |
|
|
compatible strings
This property is required. See Important properties for more information. |
|
|
register space
See Important properties for more information. |
|
|
name of each register space
|
|
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interrupts for device
See Important properties for more information. |
|
|
extended interrupt specifier for device
|
|
|
name of each interrupt
|
|
|
phandle to interrupt controller node
|
|
|
Human readable string describing the device (used as device_get_binding() argument)
See Important properties for more information. This property is deprecated. |
|
|
Clock gate information
|
|
|
name of each clock
|
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|
number of address cells in reg property
|
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number of size cells in reg property
|
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DMA channels specifiers
|
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|
Provided names of DMA channel specifiers
|
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|
IO channels specifiers
|
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|
Provided names of IO channel specifiers
|
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mailbox / IPM channels specifiers
|
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|
Provided names of mailbox / IPM channel specifiers
|
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Power domain specifiers
|
|
|
Provided names of power domain specifiers
|
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Number of cells in power-domains property
|
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Do not initialize device automatically on boot. Device should be manually
initialized using device_init().
|
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|
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.
|
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Automatically configure the device for runtime power management after the
init function runs.
|
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List of power states that will disable this device power.
|
Specifier cell names
clock cells: id