On 2/19/2019 2:06 AM, Rob Herring wrote:
> On Tue, Feb 12, 2019 at 12:44 AM Mark Zhang <markz@xxxxxxxxxx> wrote:
>>
>> Adding documentation for 3 new backup battery charging dts
>> properties:
>> - maxim,charging-current-microamp
>> - maxim,charging-voltage-microvolt
>> - maxim,output-resister-ohms
>
> What's the difference between the 77620 and 77650 as there's patches
> on the list for the 77650 too. The properties are similar, but seems
> to be main vs. backup battery charger. We should have common
> properties for this.
Rob, it's different. The RTC in max77620 is supplied from a backup
battery and consumes 2.0uA (IBBATT) when no other power sources are
available. So unlike max77620 battery charging, which provides features
like:
static enum power_supply_property max77650_charger_properties[] = {
POWER_SUPPLY_PROP_STATUS,
POWER_SUPPLY_PROP_ONLINE,
POWER_SUPPLY_PROP_CHARGE_TYPE
};
For backup battery charging in max77620, what we can do is just setting
those 3 parameters. We don't know whether it's charging, whether the
backup battery is online, the percentage of the charging progress, and
etc. That's why I mentioned before that it's not appropriate to create
it as a power supply driver.
Mark
>
>> Signed-off-by: Mark Zhang <markz@xxxxxxxxxx>
>> ---
>> .../devicetree/bindings/mfd/max77620.txt | 20 +++++++++++++++++++
>> 1 file changed, 20 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/mfd/max77620.txt b/Documentation/devicetree/bindings/mfd/max77620.txt
>> index 9c16d51cc15b..88825eaf2567 100644
>> --- a/Documentation/devicetree/bindings/mfd/max77620.txt
>> +++ b/Documentation/devicetree/bindings/mfd/max77620.txt
>> @@ -122,6 +122,26 @@ For DT binding details of different sub modules like GPIO, pincontrol,
>> regulator, power, please refer respective device-tree binding document
>> under their respective sub-system directories.
>>
>> +Backup Battery:
>> +==============
>> +This sub-node configure charging backup battery of the device. Device has
>> +support of charging the backup battery. The subnode name is "backup-battery".
>> +The property for backup-battery child nodes as:
>> +Presence of this child node will enable the backup battery charging.
>> +
>> +Optional properties:
>> + -maxim,charging-current-microamp: Charging current setting.
>> + The device supports 50/100/200/400/600/800uA.
>> + If this property is unavailable then it will
>> + charge with 50uA.
>> + -maxim,charging-voltage-microvolt: Charging Voltage Limit Setting.
>> + Device supports 2500000/3000000/3300000/350000uV.
>> + Default will be set to 2500mV. The voltage will be roundoff
>> + to nearest lower side if other than above is configured.
>> + -maxim,output-resister-ohms: Output resistor on Ohm.
>> + Device supports 100/1000/3000/6000 Ohms.
>> + Default will be set to 1000 Ohm.
>> +
>> Example:
>> --------
>> #include <dt-bindings/mfd/max77620.h>
>> --
>> 2.19.2
>>
