Configuring a Timer to measure high time on a GPIO

[JimFouchPA]

I'd like to be able to configure a channel for TIM2 (or any 32 bit timer) on an MCU. (STM32G474 in this example) to accumulate the total HIGH time over continuous wave forms. I know I can accomplish this using IC mode and do the math in an ISR by detecting each edge, but I was wondering if there was a way to do it completely in HW.

For example I'd like to monitor the total open time in (µS) of a solenoid valve controlled by another device. So, I would like to set up TIM2 to run at 1MHz and then accumulate all the cycles that it's channel 1 is high. 

I know there are ways to kind of do this for a single waveform, but I'm looking to capture the accumulated high times over 1000's of wave forms. I would then like to be able to read & reset that timer's register every so many seconds.

[raptorhal2]

Start and stop a second timer with each pulse and then read the second timer accumulated count register when done ?

[waclawek.jan]

Connect the external signal to TIMx_ETR and select it as TRGI source TIMx_SMCR.TS=0b111 (you can try also TIMx_CH1 or TIMx_CH2 and .TS=0b101/0b110 respectively); then set TIMx_SMCR.SMS=0b101 for Gated mode.

Clock the timer from internal clock as usually.

JW