* Ladislav Michl [off-list ref] [171212 18:06]:

On Tue, Dec 12, 2017 at 09:00:54AM -0800, Tony Lindgren wrote:

quoted

Hmm what do you mean? We don't want to export tons of custom functions from
the timers in and then be in trouble when at some point we have a Linux
generic hw timer framework. We already had to deal with these custom
exports earlier with conversion to multiarch and then again with
device tree.

For now, it's best to pass the timer information to the pwm driver in
platform data. In the long run that will be much easier to deal with than
fixing random drivers tinkering with the timer registers directly.

All that register access would happen only in drivers/clocksource/timer-dm.c?
So platform data will hold all function pointers needed for event capture
and the pwm driver will do only interface to pwm framework.

Yes please.

quoted

Ideally the pwm driver would just do a request_irq from the dmtimer code
where dmtimer code would implement an interrupt controller. That would
be already most fo the Linux generic hardware timer framework right there :)

I do not follow. Each general-purpose timer module has its own interrupt line,
so claiming that irq directly using request_irq seems enough. Could you
explain interrupt controller idea a bit more?

Well let's assume we have drivers/clocksource/timer-dm.c implement
an irq controller. Then the pwm driver would just do:

pwm9: dmtimer-pwm {
	compatible = "ti,omap-dmtimer-pwm";
	#pwm-cells = <3>;
	ti,timers = <&timer9>;
	ti,clock-source = <0x00>; /* timer_sys_ck */
	interrupts-extended = <&timer9 IRQ_TYPE_SOMETHING>;
};

Then you can do whatever you need to in the pwm driver with
enable_irq/disable_irq + a handler?

If reading the line status is needed.. Then maybe the GPIO framework
needs to have hardware timer support instead?

Anyways, just thinking out loud how we could have a Linux generic
hardware timer framework that drivers like pwm could then use.

Regards,

Tony