On Wednesday 12 September 2012, Rajanikanth HV wrote:
On Tuesday 11 September 2012 04:52 PM, Arnd Bergmann wrote:
On Tuesday 11 September 2012, Rajanikanth HV wrote:
Consider: USB charging: ______________________ | | --(Vbus)-->| USB Charger with | | Charger FSM (h/w) | |______________________| | | | |(Vbat and other signals) | __|_____ to | | |(GaugeSense Charger FSM| | LION | Signal) _____________ | |Battery |----------->|FuelGauge blk| | |________| |{Coulomb Ctr}| | | ------------- | <Thermistor> | | | | (BatCtrl Signal) |_______|---------->[Btemp blk] | | [ADC] |__Btemp_Low |__Btemp_Med |__Btemp_High
Note: Charging algorithm is a logical entity.
and what their purpose is? a) Coulomb counter comprises '12bit adc' and an 'N sample average/accumulation' logic helps to measure battery capacity Note: The charge and the discharge current of the battery is converted to voltage by an external resistor connected between GaugeSenseP and GaugeSenseN pins.
b) Battery temperature monitoring comprises a comparator which is enabled only by HW (charger state machine) helps to measure the thermal threshold Note: The accuracy of the battery temperature measurement depends of the accuracy of the thermistor used.
c) Charger provides 'Constant Current Constant Voltage' USB and Main(Wall) Charging support, it embeds: voltage detection, thermal protection, Constant voltage charging with programmable level, clock dithering and battery voltage monitoring
e.g. Correlation between charger and Btemp
if the battery temperature is higher than “MaxTemp °C, the charger does not start, but is enabled
if the battery temperature is between 0°C and “MaxTemp” °C charging is done in AB8500 Hardware control mode
charging is done in DB8500 Software control mode, if the battery: has a voltage higher than the “BattOK Threshold
If the battery temperature is between -10°C and 0°C: charging is done in AB8500 Hardware control mode
If the battery temperature is below -10°C, charging is done in AB8500 Hardware control mode
Ok, thanks for the explanation, this is starting to make a lot more sense. So the three blocks (fb, btemp, charger) are all separate mfd cells, each with their own register set in ab8500 and a separate driver in drivers/power, right?
Then there is the ab8500-charalg driver which I guess is implementing the Charger FSM you mention above, but it doesn't have any registers in the ab8500 but rather ties the other drivers together.
If this is true, I don't understand what makes the 'supplied-to' properties you list in the device tree binding board specific. Are they not always done the same way? If so, you could just leave them out.
What does indeed seem to be needed is a place to identify the battery type, but it's not clear if the btemp device is the best place for that (maybe it is). For this, I would suggest you give a list of possible batteries and require a property such as
st-ericsson,battery-type: A string identifier for the type of battery, which impacts how an operating system interpret the sensor readings. Possible values include: * "none" -- no battery connected * "li-ion-9100" -- Type 9100 Li-ION battery * <add any others that apply here>
Arnd