Re: Reaching DT, from driver attached to i2c/spi.

[Jared McNeill <jmcneill%invisible.ca@localhost>]

Hi Artturi --

To read a single cell value, you can use of_getprop_uint32, which takes 
care of byteswapping as needed. Example:

	if (of_getprop_uint32(sc->sc_node, "netbsd,bmx-period", &period) != 0)
		period = BMX_DEFAULT_PERIOD;

For boolean properties, you don't need to provide a value, so in the DT:

	netbsd,bmx-forced;

Means "forced = true", which you can set in code like this:

	forced = of_hasprop(sc->sc_node, "netbsd,bmx-forced");

As far as using non-standard bindings, it is generally discouraged but it 
is understood that exceptions sometimes need to be made. Can you describe 
what these properties are for and why the standard bindings aren't 
sufficient?

Cheers,
Jared


On Thu, 24 Jan 2019, Artturi Alm wrote:

> Hi,
>
> how should/could this be done?
> if bindings like "netbsd,..." are unwanted, i'll just hardcode and be
> done with this, np. :]
>
> use-case example called from _attach() below, see /* XXX .. */.
> -Artturi
>
>
> /*
> * node examples for i2c controllers in DT:
> * 			pressure@76 {
> *				compatible = "bosch,bme280";
> *				reg = <0x76>;
> *				netbsd,bmx-forced = < 0x01 >;
> *				netbsd,bmx-period = < 0x08 >;
> *				netbsd,bmx-standby = < 0x3d090 >;
> *				netbsd,bmx-oversample-temp = < 0x01 >;
> *				netbsd,bmx-oversample-pres = < 0x00 >;
> *				netbsd,bmx-oversample-humi = < 0x01 >;
> *			};
> *			pressure@77 {
> *				compatible = "bosch,bmp280";
> *				reg = <0x77>;
> *				netbsd,bmx-period = < 0x04 >;
> *				netbsd,bmx-standby = < 0x3d0900 >;
> *				netbsd,bmx-oversample-temp = < 0x01 >;
> *				netbsd,bmx-oversample-pres = < 0x01 >;
> *			};
> */
> void
> bmx_getconfig(struct bmx_softc *sc)
> {
> 	int ph = sc->sc_node;
> 	/* XXX OF_getpropint ... */
> #define	OF_getpropint(x,y,z)	((z))	/* XXX replace with ? z == default */
> 	int forced = OF_getpropint(ph, "netbsd,bmx-forced", 0);
> 	int period = OF_getpropint(ph, "netbsd,bmx-period", 1);
> 	uint32_t iirfilt = OF_getpropint(ph, "netbsd,bmx-filter", 0);
> 	uint32_t standby = OF_getpropint(ph, "netbsd,bmx-standby", 1000000);
> 	uint32_t os_temp = OF_getpropint(ph, "netbsd,bmx-oversample-temp", 1);
> 	uint32_t os_pres = OF_getpropint(ph, "netbsd,bmx-oversample-pres", 1);
> 	uint32_t os_humi = OF_getpropint(ph, "netbsd,bmx-oversample-humi", 1);
>
> 	sc->sc_node = ph; /* because __unused for now.. */
>
> 	if (sc->sc_state & BMX_S_GOTPARAMS)
> 		return;
> 	sc->sc_state |= BMX_S_GOTPARAMS;
>
> 	sc->sc_mode =
> 	    forced ? BMX280_CTRL_MEAS_FORCED : BMX280_CTRL_MEAS_NORMAL;
>
> 	iirfilt = bmx_config_filter(iirfilt);
> 	standby = bmx_config_standby(standby, BMX_W_HUMI(sc));
> 	sc->sc_config[0] = iirfilt | standby;
>
> 	os_humi = bmx_oversample(os_humi, BMX_HUMI);
> 	sc->sc_config[1] = os_humi;
>
> 	os_temp = bmx_oversample(os_temp, BMX_TEMP);
> 	os_pres = bmx_oversample(os_pres, BMX_PRES);
> 	sc->sc_config[2] = os_temp | os_pres;
> }