On Tue, 2024-12-03 at 10:08 +0100, Thomas Antoine wrote: > On 12/3/24 07:47, André Draszik wrote: > > Hi Thomas, > > > > Thanks for looking into this! > > Hi, > > With pleasure! This is my first time trying to contribute to the kernel > so sorry for any beginner mistakes I might do. No worries :-) > > > > From: Thomas Antoine <t.antoine@xxxxxxxxxxxx> > > > > > > The Maxim max77759 fuel gauge has the same interface as the Maxim max1720x > > > except for the non-volatile memory slave address which is not available. > > > > It is not fully compatible, and it also has a lot more registers. > > > > For example, the voltage now is not in register 0xda as this driver assumes. > > With these changes, POWER_SUPPLY_PROP_VOLTAGE_NOW just reads as 0. 0xda > > doesn't exist in max77759 > > > > I haven't compared in depth yet, though. > > Is the voltage necessary for the driver? If so, we could just not > read the voltage. If it is necessary, I can try to kook into it and try > to find in which register it is located (if there is one). Downstream reports it in https://android.googlesource.com/kernel/google-modules/bms/+/refs/heads/android-gs-raviole-mainline/max1720x_battery.c#2400 so upstream should do, too. > > > static const char *const max17205_model = "MAX17205"; > > > +static const char *const max77759_model = "MAX77759"; > > > > > > struct max1720x_device_info { > > > struct regmap *regmap; > > > @@ -54,6 +57,21 @@ struct max1720x_device_info { > > > int rsense; > > > }; > > > > > > +struct chip_data { > > > + u16 default_nrsense; /* in regs in 10^-5 */ > > > + u8 has_nvmem; > > > +}; > > > + > > > +static const struct chip_data max1720x_data = { > > > + .default_nrsense = 1000, > > > + .has_nvmem = 1, > > > +}; > > > + > > > +static const struct chip_data max77759_data = { > > > + .default_nrsense = 500, > > > + .has_nvmem = 0, > > > +}; > > > > This should be made a required devicetree property instead, at least for > > max77759, as it's completely board dependent, 'shunt-resistor-micro-ohms' > > is widely used. > > > > I also don't think there should be a default. The driver should just fail > > to probe if not specified in DT (for max77759). > > I hesitated to do this but I didn't know what would be better. Will change > for v2. Just to clarify, has_nvmem can stay here in the driver, just rsense should go into DT is what I mean. > > > + > > > /* > > > * Model Gauge M5 Algorithm output register > > > * Volatile data (must not be cached) > > > @@ -369,6 +387,8 @@ static int max1720x_battery_get_property(struct > > > power_supply *psy, > > > val->strval = max17201_model; > > > else if (reg_val == MAX172XX_DEV_NAME_TYPE_MAX17205) > > > val->strval = max17205_model; > > > + else if (reg_val == MAX172XX_DEV_NAME_TYPE_MAX77759) > > > + val->strval = max77759_model; > > > else > > > > This is a 16 bit register, and while yes, MAX172XX_DEV_NAME_TYPE_MASK only > > cares about the bottom 4 bits, the register is described as 'Firmware > > Version Information'. > > > > But maybe it's ok to do it like that, at least for now. > > I thought this method would be ok as long as there is no collision on > values. I hesitated to change the model evaluation method based on chip > model, where the max77759 would thus have an hard-coded value and the > max1720x would still evaluate the register value. I did not do it because > it led to a lot more changes for no difference. Downstream uses the upper bits for max77759: https://android.googlesource.com/kernel/google-modules/bms/+/refs/heads/android-gs-raviole-mainline/max_m5.h#135 I don't know what the original max17201/5 report in this register for those bits, though. Given for max77759 this register returns the firmware version, I assume the lower bits can change. Cheers, Andre'
