nxp,fmeas

Description

NXP BASIC Frequency Measurement (FREQME / fmeas) module.

Single-register FREQMECTRL variant (RT6xx / RT5xx / RW6xx) driven through
the MCUX SDK fsl_fmeas HAL. Measures a target clock against a reference
clock and returns the result in Hz. The reference and target inputs are
routed through the INPUTMUX peripheral via the Zephyr mux subsystem.

This hardware has no interrupt line and no MIN/MAX threshold registers, so
the Zephyr clock_monitor MEASURE (one-shot) mode is the only mode supported;
WINDOW mode is rejected with -ENOTSUP. The measurement window is HW/HAL-fixed
at 2^20 reference-clock cycles, so a MEASURE window_ns request is advisory.

Selectable clock sources are declared with two container child nodes,
"reference-sources" and "target-sources". Each container holds one child
node per selectable source, pairing an INPUTMUX route with an optional
frequency provider. The child marked "default-source" is the power-on
selection. clock_monitor_set_source() switches between the declared sources
at runtime, keyed by the INPUTMUX connection cookie (see mux-states).

A source's frequency provider is either "clock-frequency" (a fixed constant
in Hz) or "clocks" (queried through clock_control_get_rate()). When both are
present "clock-frequency" wins. A reference source must resolve to a nonzero
frequency (required by the driver to convert the raw result counter into Hz).
A target source may omit both (MEASURE-only; no frequency is predicted).

The driver does not enable the selected source clocks. The application must
ensure the chosen reference and target clocks are running before
configure()/start(); a source left off simply measures zero edges and is
reported as CLOCK_LOST.

Place NXP_FMEAS_*_REF_* cookies in "reference-sources" children and
NXP_FMEAS_*_TAR_* (or the shared NXP_FMEAS_* cookies) in "target-sources"
children. See <zephyr/dt-bindings/clock-monitor/nxp-fmeas.h>.

Properties

Top level properties

These property descriptions apply to “nxp,fmeas” nodes themselves. This page also describes child node properties in the following sections.

Node specific properties

Properties not inherited from the base binding file.

Name

Type

Details

resets

phandle-array

 
FREQME peripheral reset line. The driver toggles it once at init to
release the block from reset; without it the FREQMECTRL register is
inert (writes dropped, reads return 0) and every measurement reports 0.

This property is required.

reset-names

string-array

 
Name of each reset

Deprecated node specific properties

Deprecated properties not inherited from the base binding file.

(None)

Base properties

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 “nxp,fmeas” compatible.

Name

Type

Details

reg

array

 
Information used to address the device. The value is specific to
the device (i.e. is different depending on the compatible
property).

The "reg" property is typically a sequence of (address, length) pairs.
Each pair is called a "register block". Values are
conventionally written in hex.

For details, see "2.3.6 reg" in Devicetree Specification v0.4.

This property is required.

See Important properties for more information.

clocks

phandle-array

 
FREQME peripheral gate clock (ipg), enabled by the driver via
clock_control_on().

This property is required.

status

string

 
Indicates the operational status of the hardware or other
resource that the node represents. In particular:

  - "okay" means the resource is operational and, for example,
    can be used by device drivers
  - "disabled" means the resource is not operational and the system
    should treat it as if it is not present

For details, see "2.3.4 status" in Devicetree Specification v0.4.

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

See Important properties for more information.

compatible

string-array

 
This property is a list of strings that essentially define what
type of hardware or other resource this devicetree node
represents. Each device driver checks for specific compatible
property values to find the devicetree nodes that represent
resources that the driver should manage.

The recommended format is "vendor,device", The "vendor" part is
an abbreviated name of the vendor. The "device" is usually from
the datasheet.

The compatible property can have multiple values, ordered from
most- to least-specific. Having additional values is useful when the
device is a specific instance of a more general family, to allow the
system to match the most specific driver available.

For details, see "2.3.1 compatible" in Devicetree Specification v0.4.

This property is required.

See Important properties for more information.

reg-names

string-array

 
Optional names given to each register block in the "reg" property.
For example:

  / {
       soc {
           #address-cells = <1>;
           #size-cells = <1>;

           uart@1000 {
               reg = <0x1000 0x2000>, <0x3000 0x4000>;
               reg-names = "foo", "bar";
           };
       };
  };

The uart@1000 node has two register blocks:

  - one with base address 0x1000, size 0x2000, and name "foo"
  - another with base address 0x3000, size 0x4000, and name "bar"

ranges

compound

 
Information used to define a mapping (or translation) between the address
space of a bus (the "child address space") and the address space of the
bus node's parent (the "parent address space").

The "ranges" property is typically empty, or a sequence of triplets
(child bus address, parent bus address, length).

If the "ranges" property is empty, it specifies that the parent and child
address spaces are identical and no address translation is required.

If the "ranges" property is not present in a bus node, it is assumed that
no mapping exists between children of the node and the parent address space.

For details, see "2.3.8 ranges" in Devicetree Specification v0.4.

interrupts

array

 
Information about interrupts generated by the device, encoded as an array
of one or more interrupt specifiers. The format of the data in this property
varies by where the device appears in the interrupt tree. Devices with the same
"interrupt-parent" will use the same format in their interrupts properties.

For details, see "2.4 Interrupts and Interrupt Mapping" in
Devicetree Specification v0.4.

See Important properties for more information.

interrupts-extended

compound

 
Extended interrupt specifier for device, used as an alternative to
the "interrupts" property.

For details, see "2.4 Interrupts and Interrupt Mapping" in
Devicetree Specification v0.4.

interrupt-names

string-array

 
Optional names given to each interrupt generated by a device.
The interrupts themselves are defined in either "interrupts" or
"interrupts-extended" properties.

For details, see "2.4 Interrupts and Interrupt Mapping" in
Devicetree Specification v0.4.

interrupt-parent

phandle

 
If present, this refers to the node which handles interrupts generated
by this device.

For details, see "2.4 Interrupts and Interrupt Mapping" in
Devicetree Specification v0.4.

label

string

 
Human readable string describing the device. Use of this property is
deprecated except as needed on a case-by-case basis.

For details, see "4.1.2 Miscellaneous Properties" in Devicetree
Specification v0.4.

See Important properties for more information.

clock-names

string-array

 
Optional names given to each clock provider in the "clocks" property.

#address-cells

int

 
This property encodes the number of <u32> cells used by address fields
in "reg" properties in this node's children.

For details, see "2.3.5 #address-cells and #size-cells" in Devicetree
Specification v0.4.

#size-cells

int

 
This property encodes the number of <u32> cells used by size fields in
"reg" properties in this node's children.

For details, see "2.3.5 #address-cells and #size-cells" in Devicetree
Specification v0.4.

dma-coherent

boolean

 
Indicates that the device is capable of coherent DMA operations.

For details, see "2.3.10 dma-coherent" in Devicetree Specification v0.4.

dmas

phandle-array

 
DMA channel specifiers relevant to the device.

dma-names

string-array

 
Optional names given to the DMA channel specifiers in the "dmas" property.

dma-ranges

compound

 
The dma-ranges provides a means of defining a mapping or translation between the
physical address space of the bus and the physical address space of the parent of the bus.

For details, see "2.3.9 dma-ranges" in Devicetree Specification v0.4.

io-channels

phandle-array

 
IO channel specifiers relevant to the device.

io-channel-names

string-array

 
Optional names given to the IO channel specifiers in the "io-channels" property.

mboxes

phandle-array

 
Mailbox / IPM channel specifiers relevant to the device.

mbox-names

string-array

 
Optional names given to the mbox specifiers in the "mboxes" property.

power-domains

phandle-array

 
Power domain specifiers relevant to the device.

power-domain-names

string-array

 
Optional names given to the power domain specifiers in the "power-domains" property.

#power-domain-cells

int

 
Number of cells in power-domains property

hwlocks

phandle-array

 
HW spinlock id relevant to the device.

hwlock-names

string-array

 
Optional names given to the hwlock specifiers in the "hwlocks" property.

zephyr,deferred-init

boolean

 
Do not initialize device automatically on boot. Device should be manually
initialized using device_init().

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.

zephyr,pm-device-runtime-auto

boolean

 
Automatically configure the device for runtime power management after the
init function runs.

zephyr,disabling-power-states

phandles

 
List of power states that will disable this device power.

Grandchild node properties

Name

Type

Details

mux-states

phandle-array

 
INPUTMUX route for this source, given as a single mux-states entry
<&inputmux channel connection> where:
  - &inputmux is the INPUTMUX mux controller
  - channel selects the FMEASURE_CH_SEL slot:
      0 = reference (FMEASURE_CH_SEL[0])
      1 = target    (FMEASURE_CH_SEL[1])
  - connection is an NXP_FMEAS_* cookie from
    <zephyr/dt-bindings/clock-monitor/nxp-fmeas.h>.
The connection cookie is also the runtime clock_monitor_set_source()
selector for this source.

This property is required.

clocks

phandle-array

 
Frequency provider queried through clock_control_get_rate().
Ignored when clock-frequency is present.

clock-frequency

int

 
Fixed frequency provider in Hz, used verbatim without querying
clock_control. Takes precedence over clocks. Use for sources whose
rate the clock_control driver cannot report (e.g. an external
crystal).

default-source

boolean

 
Marks this source as the power-on selection for its container.
Exactly one child of each container must set it.

mux-controls

phandle-array

 
List of MUX controller specifiers. Each entry is a phandle to a MUX
controller followed by #mux-control-cells addressing cells.

mux-control-names

string-array

 
Optional names for the entries in "mux-controls"

mux-state-names

string-array

 
Optional names for the entries in "mux-states"