From: Mark Kettenis <mark.kettenis@xs4all.nl>
Subject: Re: scmi: hook up to cpu_* to get apm working
To: Tobias Heider <tobias.heider@stusta.de>
Cc: tech@openbsd.org, patrick@openbsd.org, kettenis@openbsd.org
Date: Fri, 23 May 2025 00:20:50 +0200

> Date: Thu, 22 May 2025 07:16:17 +0200
> From: Tobias Heider <tobias.heider@stusta.de>
> 
> On Snapdragon X Elite chips we have to use ARM SCMI to control cpu
> performance.  Our driver now supports reading the current
> performance level, translating it to HZ and exporting it as a sensor
> as well as setting initial levels.
> 
> I think it is time to hook everything up to cpu_setperf and
> cpu_clockspeed to make those controls available to apm and
> hw.setperf.  Loosely inspired by aplcpu which deals with a similar
> problem on Apple machines.
> 
> ok? test feedback?

I think this should take pl_perf into account in mapping the perflevel
into a level.

> Index: scmi.c
> ===================================================================
> RCS file: /cvs/src/sys/dev/fdt/scmi.c,v
> diff -u -p -r1.3 scmi.c
> --- scmi.c	22 May 2025 03:04:01 -0000	1.3
> +++ scmi.c	22 May 2025 03:37:38 -0000
> @@ -484,6 +484,9 @@ int	scmi_perf_level_get(struct scmi_soft
>  int	scmi_perf_level_set(struct scmi_softc *, int, int);
>  void	scmi_perf_refresh_sensor(void *);
>  
> +int	scmi_perf_cpuspeed(int *);
> +void	scmi_perf_cpusetperf(int);
> +
>  void
>  scmi_attach_perf(struct scmi_softc *sc, int node)
>  {
> @@ -558,6 +561,10 @@ scmi_attach_perf(struct scmi_softc *sc, 
>  	}
>  	sensordev_install(&sc->sc_perf_sensordev);
>  	sensor_task_register(sc, scmi_perf_refresh_sensor, 1);
> +
> +	cpu_setperf = scmi_perf_cpusetperf;
> +	cpu_cpuspeed = scmi_perf_cpuspeed;
> +
>  	return;
>  err:
>  	free(sc->sc_perf_fsensors, M_DEVBUF,
> @@ -647,6 +654,63 @@ scmi_perf_level_set(struct scmi_softc *s
>  		return -1;
>  	}
>  	return 0;
> +}
> +
> +int
> +scmi_perf_cpuspeed(int *freq)
> +{
> +	struct scmi_softc *sc;
> +	int i, level = -1;
> +	uint64_t opp_hz = 0;
> +
> +        for (i = 0; i < scmi_cd.cd_ndevs; i++) {
> +                sc = scmi_cd.cd_devs[i];
> +                if (sc == NULL)
> +                        continue;
> +
> +		if (sc->sc_perf_domains == NULL)
> +			continue;
> +
> +		for (i = 0; i < sc->sc_perf_ndomains; i++) {
> +			if (sc->sc_perf_domains[i].pd_levels == NULL)
> +				return EINVAL;
> +
> +			level = scmi_perf_level_get(sc, i);
> +			opp_hz = MAX(opp_hz, (uint64_t)sc->sc_perf_domains[i].
> +		    	    pd_levels[level].pl_ifreq * 1000);
> +		}
> +	}
> +
> +	if (opp_hz == 0)
> +		return EINVAL;
> +
> +	*freq = opp_hz / 1000000;
> +	return 0;
> +}
> +
> +void
> +scmi_perf_cpusetperf(int level)
> +{
> +	struct scmi_softc *sc;
> +	size_t nlevels;
> +	int i;
> +
> +        for (i = 0; i < scmi_cd.cd_ndevs; i++) {
> +                sc = scmi_cd.cd_devs[i];
> +                if (sc == NULL)
> +			return;
> +		if (sc->sc_perf_domains == NULL)
> +			continue;
> +
> +		/* Find number of levels per domain */
> +		for (i = 0; i < sc->sc_perf_ndomains; i++) {
> +			nlevels = sc->sc_perf_domains[i].pd_nlevels;
> +			if (nlevels == 0)
> +				continue;
> +			scmi_perf_level_set(sc, i,
> +			    (level * (nlevels - 1) / 100));
> +		}
> +	}
>  }
>  
>  void
> 
>