dt-binding for timers

[maxvankessel]

I can' t wrap my head around the timer binding.

Currently I'm developing on a STM32F4 soc. And using the timer for multiple things.
So I've created an out-of-tree timer driver to support reading HALL sensors (which is a feature of the timer)
I've also supported the advanced timer functionality of the timer to drive a motor.

But every time I copy code from driver to driver to do the same thing, like get_cycles_per_sec to read absolute motor speed.

Normal procedure would be to ask the base what the tick rate is.
But the stm32 timer has no module.

I do not mind creating code out-of-tree, actually I find it liberating. But the extensibility of the timer-binding is a bit unnatural. Its not as natural as the spi-controller spi-device bindings, e.g.

&spi4 {
	status = "okay";
	cs-gpios = <&gpioe 4 0> , <&gpioe 3 0>;
	drv0: drv832x@0 {
		compatible = "ti,drv832x";
		reg = <0>;
		spi-max-frequency = <1000000>;
		label = "DRIVE";
		fault-gpios = <&gpioe 15 (GPIO_INT | GPIO_INT_EDGE)>;
		calibration-gpios = <&gpioe 14 GPIO_DIR_OUT>;
	};

	drv1: drv832x@1 {
		compatible = "ti,drv832x";
		reg = <1>;
		spi-max-frequency = <1000000>;
		label = "LEVEL";
		fault-gpios = <&gpioc 4 (GPIO_INT | GPIO_INT_EDGE)>;
		calibration-gpios = <&gpioc 5 GPIO_DIR_OUT>;
	};
};

This way, the (bridge-)driver does know on which bus its working.

So timer2 has 4 channels, and I'm using only three of the hall driver, but I would like to know what my who parent is and use parent specific functions. And use the instances instead of using the dts_fixups.h

&timers2 {
	status = "okay";
	hall {
		compatible = "st,stm32-hall";
		label = "DRIVE_HALL";
		interrupts = <28 0>;
		interrupt-names = "global";
		st,in-gpios = <&gpiob 10 GPIO_DIR_IN>, <&gpiob 9 GPIO_DIR_IN>, <&gpiob 8 GPIO_DIR_IN>;
		st,prescaler = <8>;
		st,filter = <0>;
		st,commutation = <0>;
		st,polarity = "both";
		status = "okay";
	};
};

Maybe throw in a #address-cells and size, to make a relative offset. Something like this

And eventually support something like this:

&timers2 {
	status = "okay";
	st,prescaler = <0>;

	pwm: pwm@0{
		compatible = "st,stm32-pwm";
		reg = <0 3>;
		status = "okay";
	};

	capture: cap@3 {
		compatible = "st,stm32-capture";
		reg = <3 1>;
		status = "okay";
	};
};

Side note: capture would then be part of the iio drivers.

My goal is to start a discussion, maybe it's already on the agenda, then I would like to know where I could find more information.

Thanks

[maxvankessel]

This is what I've come up with so far:

&timers5 {
	status = "okay";

	timer {
		#address-cells = <1>;
		#size-cells = <0>;
		compatible = "st,stm32-cc-timer";
		label = "SYNC";
		st,master-slave-mode;
		st,slave-mode = <4>;			/* Reset timer */
		st,slave-trigger-in = <0>;		/* ITR0 */
		status = "okay";

		compare: cc1@0 {
			reg = <0>;			/* channel 1 */
			compatible = "st,stm32-compare";
			label = "TIM5_CC1";
			status = "okay";
		};
	};
};

It has a timer-controller.yaml and a timer-device.yaml But it still is a timer inside a timer which uses dts-fixups

[erwango]

@maxvankessel, I'd suggest to have a look to latest timers/pwm bindings. I think this should answer your querry.
I'm closing the point for now. Feel free to reopen if needed.

[krebsbstn]

I wanted to use the functionality of master/slave modes on an stm32-h7a3zi-q.
I tougth I found the correct solution when i ran over this issue,
but I had to realize that the suggestions made by @maxvankessel have never been merged to zephyr master.
Even though this is needed to get two PWMs into sync.

@erwango
As your comment suggests, there is another way of synchronizing two timers to get aligned PWMs?

The Datasheet of STM32-H7A2ZI-Q tells there is the "Timer Link feature" avalible.
Could you please point out how to sync the PWMs via dts?

[erwango]

@krebsbstn This issue is 3 years old. Lot of things changed during this time. Please open a new issue describing your need.

[krebsbstn]

@krebsbstn This issue is 3 years old. Lot of things changed during this time. Please open a new issue describing your need.

Done, can be found here: #52490