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infineon,xmc4xxx-ccu8-pwm

Vendor: Infineon Technologies

Note

An implementation of a driver matching this compatible is available in drivers/pwm/pwm_xmc4xxx_ccu8.c.

Description

Infineon XMC4XXX PWM Capture Compare Unit 8 (CCU8) module

The PWM CCU8 module can automatically generate a high-side
and a low-side PWM signal, where the two signals are complementary
to each other.

The module supports adding a dead time between the high-side and
low-side PWM signals.

The dead time ensures that there is a delay before the PWM state
transitions from 0 to 1, preventing the high-side and low-side
switches from being on simultaneously.

There are two CCU8 modules with DTS node labels: pwm_ccu80 and
pwm_ccu81. Each module has four slices, and each slice has
two channels. A channel consists of a corresponding high-side
and low-side PWM signal.

The CCU8 modules use the CCU clock source. Each slice applies
a separate prescaler to divide the clock. The clock divider is
defined by the 'slice-prescaler' property. Additionally, each
slice has a dead time prescaler, which divides the slice clock
for the dead time counter.

Device tree example:
A node can define a 'pwm' field, usually referenced in a 'pwms'
property, where the entries include the PWM module phandle,
channel number, pulse period (in nanoseconds or set using
PWM_XX() macros), and a channel
flag (PWM_POLARITY_NORMAL/PWM_POLARITY_INVERTED).

The 'pwm_ccu8' node must define the following fields:
&pwm_ccu80 {
        slice-prescaler = <15 15 15 15>;
        slice-deadtime-prescaler = <3 3 3 3>;
        channel-deadtime-high = <0 0 0 0 PWM_MSEC(100) 0 0 0>;
        channel-deadtime-low = <0 0 0 0 PWM_MSEC(100) 0 0 0>;
        pinctrl-0 = <&pwm_out_p5_9_ccu80_ch4_high &pwm_out_p0_0_ccu80_ch4_low>;
        pinctrl-names = "default";
};

This will configure channel 4 with a 100msec deadtime on the high
and low side PWM signals.

Another node can reference the PWM as follows:
&test_node {
   ...
   pwms = <&pwm_ccu80 0 PWM_SEC(1) PWM_POLARITY_NORMAL>;
   ...
};

The 'pwm_out_p{PORT}_{PIN}_ccu8{MODULE_IDX}_ch{CHANNEL_IDX}_{HIGH_LOW}'
format is used for CCU8 pinctrl nodes. 'MODULE_IDX' and 'CHANNEL_IDX'
refer to a specific 'pwm_ccu8x' module and channel, respectively.
'PORT/PIN' defines the GPIO that the channel connects to.
'HIGH_LOW' indicates whether the pin is for the high or low-side signal.

It's not necessary to specify both the high and low pinctrls. Only the low-side
signal can, for example, be used as PWM, but note that the duty cycle of the
low signal will be (1 - duty) as set via the API.

Note that a slice has two channels. Channels 0/1 are in slice 0,
channels 2/3 are in slice 1, and so on. Each channel can have its own
duty cycle and high/low dead times. But the pulse duration applies to
both channels. Thus, when using the PWM control api to modify the pulse width
on a channel 0, it will also be updated for channel 1 since they are
in the same slice.

Properties

Properties not inherited from the base binding file.

Name

Type

Details

pinctrl-0

phandles

 
Pin configuration/s for the first state. Content is specific to the
selected pin controller driver implementation.

This property is required.

pinctrl-names

string-array

 
Names for the provided states. The number of names needs to match the
number of states.

This property is required.

slice-prescaler

array

 
Defines the clock divider for each slice.
The entry in the array will divide CCU clock by (2 << value).
The range for the prescaler values is [0, 15].
Reducing prescaler value will improve resolution but decrease the maximum period.

This property is required.

slice-deadtime-prescaler

array

 
Defines the clock divider for dead time counter for each slice.
The range for the values is [0, 3].
Reducing prescaler value will improve dead time resolution but decrease the
maximum dead time.

This property is required.

channel-deadtime-high

array

 
Defines the dead time in nanoseconds for the high-side PWM signal for each channel.

This property is required.

channel-deadtime-low

array

 
Defines the dead time in nanoseconds for the low-side PWM signal for each channel.

This property is required.

#pwm-cells

int

 
Number of items to expect in a pwm specifier

This property is required.

Constant value: 3

pinctrl-1

phandles

 
Pin configuration/s for the second state. See pinctrl-0.

pinctrl-2

phandles

 
Pin configuration/s for the third state. See pinctrl-0.

pinctrl-3

phandles

 
Pin configuration/s for the fourth state. See pinctrl-0.

pinctrl-4

phandles

 
Pin configuration/s for the fifth state. See pinctrl-0.

Specifier cell names

  • pwm cells: channel, period, flags