Please suggest proper format for DT properties.

[Constantine Shulyupin <const@MakeLinux.com>]

Hi,

I am designing DT support for a hwmon chip. 
It has some sensors, each of them can be:
 - "disabled"
 - "thermal diode"
 - "thermistor"
 - "voltage"

Four possible options for DT properties format.

Option 1: Separated property for each sensor.

Example nct7802 node:

nct7802 {
	compatible = "nuvoton,nct7802";
	reg = <0x2a>;
	nuvoton,sensor1-type = "thermistor";
	nuvoton,sensor2-type = "disabled";
	nuvoton,sensor3-type = "voltage";
};

Option 2: Array of strings for all sensors.

nct7802 {
	compatible = "nuvoton,nct7802";
	reg = <0x2a>;
	nuvoton,sensors-types = "thermistor", "disabled", "voltage";
};

Option 3: Sets of 4 cells.

  Borrowed from marvell,reg-init and broadcom,c45-reg-init.

  The first cell is the page address, 
  the second a register address within the page,
  the third cell contains a mask to be ANDed with the existing register
  value, and the fourth cell is ORed with the result to yield the
  new register value. If the third cell has a value of zero,
  no read of the existing value is performed.

Example nct7802 node:

nct7802 {
	compatible = "nuvoton,nct7802";
	reg = <0x2a>;
	nct7802,reg-init =
		<0 0x21 0 0x01 > // START = 1
		<0 0x22 0x03 0x02>; // RTD1_MD = 2
};

Please suggest proper format for DT properties.

Thanks
Constantine

PS:
Datasheet: https://www.nuvoton.com/hq/products/cloud-computing/hardware-monitors/desktop-server-series/nct7802y/