kernel/drivers/power/supply/ab8500_bmdata.c, branch linux-6.9.y

power: supply: ab8500: Standardize BTI resistance

2022-02-28T10:34:31Z

The Battery Type Indicator (BTI) resistor is a resistor mounted between a special terminal on the battery and ground. By sending a fixed current (such as 7mA) through this resistor and measuring the voltage over it, the resistance can be determined, and this verifies the battery type. Typical side view of the battery: o o o GND BTI +3.8V Typical example of the electrical layout: +3.8 V BTI | | | + | _______ [ ] 7kOhm ___ | | | | | GND GND By verifying this resistance before attempting to charge the battery we add an additional level of security. In some systems this is used for plug-and-play of batteries with different capacity. In other cases, this is merely used to verify that the right type of battery is connected, if several batteries have the same physical shape and can be plugged into the same slot. Sometimes this is just a surplus security mechanism. Nokia and Samsung among many other vendors are known to use these BTI resistors. Add the BTI properties to struct power_supply_battery_info and switch the AB8500 charger code over to using it. Signed-off-by: Linus Walleij Signed-off-by: Sebastian Reichel

power: supply: ab8500: Standardize alert mode charging

2022-02-28T10:34:31Z

The AB8500 code is using a special current and voltage setting when the battery is in "alert mode", i.e. when it is starting to go outside normal operating conditions so it is too cold or too hot. This makes sense as a way for the charging algorithm to deal with hostile environments. Add the needed members to the struct power_supply_battery_info, and switch the AB8500 charging code over to using this. Reviewed-by: Matti Vaittineen Signed-off-by: Linus Walleij Signed-off-by: Sebastian Reichel

power: supply: ab8500: Standardize maintenance charging

2022-02-28T10:34:31Z

Maintenance charging is the phase of keeping up the charge after the battery has charged fully using CC/CV charging. This can be done in many successive phases and is usually done with a slightly lower constant voltage than CV, and a slightly lower allowed current. Add an array of maintenance charging points each with a current, voltage and safety timer, and add helper functions to use these. Migrate the AB8500 code over. This is used in several Samsung products using the AB8500 and these batteries and their complete parameters will be added later as full examples, but the default battery in the AB8500 code serves as a reasonable example so far. Reviewed-by: Matti Vaittinen Signed-off-by: Linus Walleij Signed-off-by: Sebastian Reichel

power: supply: ab8500: Integrate thermal zone

2022-02-11T19:24:53Z

Instead of providing our own homebrewn thermal measurement code for an NTC and passing tables, we put the NTC thermistor into the device tree, create a passive thermal zone, and poll this thermal zone for the temperature. Signed-off-by: Linus Walleij Signed-off-by: Sebastian Reichel

power: supply: ab8500: Swap max and overvoltage

2022-02-11T19:24:53Z

We should terminate charging when we reach the voltage_max_design_uv not overvoltage_limit_uv, this is an abuse of that struct member. The overvoltage limit is actually not configurable on the AB8500, it is fixed to 4.75 V so drop a comment about that in the code. Fixes: 2a5f41830aad ("power: supply: ab8500: Standardize voltages") Signed-off-by: Linus Walleij Signed-off-by: Sebastian Reichel

power: supply: ab8500: Drop BATCTRL thermal mode

2022-02-11T19:24:53Z

The BATCTRL mode reads the temperature of the battery by enabling a certain probing current (7-20 mA) and then measure the voltage of the NTC mounted inside the battery. None of the AB8500 product or the reference designs use this mode. What we use is the so-called BATTEMP mode which enables an internal 230 kOhm pull-up to 1.8 V to the external NTC on pin BatTemp (N16) and then measures the voltage over the NTC using the ADC: 1.8V (VTVOUT) | [ ] 230 kOhm | BatTemp +---------------- ADC Pin N16 | _ |/ [/] NTC _/| | GND Cut out the BATCTRL code to clear the forest and stop maintaining code we can never test. The current inducing method is still used to probe for the battery type using the internal BTI (battery type indicator) on the BatCtrl (C3) pin in a separate code path. Signed-off-by: Linus Walleij Signed-off-by: Sebastian Reichel

power: supply_core: Pass pointer to battery info

2022-01-03T17:53:10Z

The function to retrieve battery info (from the device tree) assumes we have a static info struct that gets populated by calling into power_supply_get_battery_info(). This is awkward since I want to support tables of static battery info by just assigning a pointer to all info based on e.g. a compatible value in the device tree. We also have a mixture of static and dynamically allocated variables here. Bite the bullet and let power_supply_get_battery_info() allocate also the memory used for the very top level struct power_supply_battery_info container. Pass pointers around and lifecycle this with the psy device just like the stuff we allocate inside it. Change all current users over. As part of the change, initializers need to be added to some previously uninitialized fields in struct power_supply_battery_info. Reviewed-By: Matti Vaittinen Signed-off-by: Linus Walleij Signed-off-by: Sebastian Reichel

power: supply: ab8500: Standardize capacity lookup

2021-11-22T16:16:26Z

The AB8500 charger only has one capacity table with unspecified temperature, so we assume this capacity is given for 20 degrees Celsius. Convert this table to use the OCV (open circuit voltage) tables in struct power_supply_battery_ocv_table. In the process, convert the fuel gauge driver to use microvolts and microamperes so we can use the same internals as the power supply subsystem without having to multiply and divide with 1000 in a few places. Also convert high_curr_threshold and lowbat_threshold to use microamperes and microvolts as these are closely related to these changes. Drop the unused overbat_threshold member in the custom struct ab8500_fg_parameters. Signed-off-by: Linus Walleij Signed-off-by: Sebastian Reichel

power: supply: ab8500: Standardize temp res lookup

2021-11-22T16:16:26Z

The lookup from battery temperature to internal resistance was using its own format. Rewrite this to use the table inside struct power_supply_battery_info:s resist_table. The supplied resistance table has to be rewritten to express the resistance in percent of the factory resistance as a side effect. We can then rely on the library function power_supply_temp2resist_simple() to interpolate the internal resistance percent from the temperature. Signed-off-by: Linus Walleij Signed-off-by: Sebastian Reichel

power: supply: ab8500: Standardize CV voltage

2021-11-22T16:16:26Z

The voltage used in the constant voltage phase of the charging exist in struct power_supply_battery_info as constant_charge_voltage_max_uv. Switch the custom property normal_vol_lvl to this and consequentially change everything that relates to this value over to using microvolts rather than millivolts so we align internal representation of current with the power core. Prefix every variable we change with *_uv to indicate the unit everywhere but also to make sure we do not miss any outlier. Signed-off-by: Linus Walleij Signed-off-by: Sebastian Reichel