Messages in this thread | | | Date | Mon, 28 Feb 2011 14:20:24 +0100 | From | Lars-Peter Clausen <> | Subject | Re: [PATCH] bq27x00: New property POWER_SUPPLY_PROP_CURRENT_MAX |
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On 02/27/2011 01:02 PM, Pali Rohár wrote: > This patch add support for reporting property POWER_SUPPLY_PROP_CURRENT_MAX > > Signed-off-by: Pali Rohár <pali.rohar@gmail.com> > > --- a/drivers/power/bq27x00_battery.c 2011-02-27 12:14:56.000000000 +0100 > +++ b/drivers/power/bq27x00_battery.c 2011-02-27 12:55:33.000000000 +0100 > @@ -4,6 +4,7 @@ > * Copyright (C) 2008 Rodolfo Giometti <giometti@linux.it> > * Copyright (C) 2008 Eurotech S.p.A. <info@eurotech.it> > * Copyright (C) 2010-2011 Lars-Peter Clausen <lars@metafoo.de> > + * Copyright (C) 2011 Pali Rohár <pali.rohar@gmail.com> > * > * Based on a previous work by Copyright (C) 2008 Texas Instruments, Inc. > * > @@ -53,11 +54,13 @@ > > #define BQ27000_REG_RSOC 0x0B /* Relative State-of-Charge */ > #define BQ27000_REG_ILMD 0x76 /* Initial last measured discharge */ > +#define BQ27000_REG_IMLC 0x7D /* Initial max load current */ > #define BQ27000_FLAG_CHGS BIT(7) > #define BQ27000_FLAG_FC BIT(5) > > #define BQ27500_REG_SOC 0x2C > #define BQ27500_REG_DCAP 0x3C /* Design capacity */ > +#define BQ27500_REG_MLI 0x1E /* Max load current */ > #define BQ27500_FLAG_DSC BIT(0) > #define BQ27500_FLAG_FC BIT(9) > > @@ -90,6 +93,7 @@ struct bq27x00_device_info { > > struct bq27x00_reg_cache cache; > int charge_design_full; > + int current_max; > > unsigned long last_update; > struct delayed_work work; > @@ -106,6 +110,7 @@ static enum power_supply_property bq27x0 > POWER_SUPPLY_PROP_PRESENT, > POWER_SUPPLY_PROP_VOLTAGE_NOW, > POWER_SUPPLY_PROP_CURRENT_NOW, > + POWER_SUPPLY_PROP_CURRENT_MAX, > POWER_SUPPLY_PROP_CAPACITY, > POWER_SUPPLY_PROP_TEMP, > POWER_SUPPLY_PROP_TIME_TO_EMPTY_NOW, > @@ -220,6 +225,32 @@ static int bq27x00_battery_read_ilmd(str > } > > /* > + * Return the battery Initial max load current in µA > + * Or < 0 if something fails. > + */ > +static int bq27x00_battery_read_imlc(struct bq27x00_device_info *di) > +{ > + int imlc; > + > + if (di->chip == BQ27500) > + imlc = bq27x00_read(di, BQ27500_REG_MLI, false); > + else > + imlc = bq27x00_read(di, BQ27000_REG_IMLC, true); > +
According to the datasheet the MLI register contains an adaptive value which is averaged each time the battery has been fully charged after previously being discharged to less then 50%. The IMLC register holds some preprogrammed value and is used to initialize the MLI register upon a battery reset. So with the current implementation you'll get different results for bq27000/bq27200 and bq27500.
Furthermore I'm not sure if the CURRENT_MAX property actually makes sense in the context of a battery. There is no entry for the CURRENT_MAX property in Documentation/power/power_supply. But according to the commit message of the commit adding that property I would assume that it is supposed to be used for chargers to indicate the maximum current that can be drawn from it. (Adding the author of that commit to Cc).
- Lars
> + if (imlc < 0) { > + dev_err(di->dev, "error reading initial max load current\n"); > + return imlc; > + } > + > + if (di->chip == BQ27500) > + imlc *= 1000; > + else > + imlc = imlc * 457000 / BQ27000_RS; > + > + return imlc; > +} > + > +/* > * Return the battery Cycle count total > * Or < 0 if something fails. > */ > @@ -275,6 +306,10 @@ static void bq27x00_update(struct bq27x0 > /* We only have to read charge design full once */ > if (di->charge_design_full <= 0) > di->charge_design_full = bq27x00_battery_read_ilmd(di); > + > + /* We only have to read current design max once */ > + if (di->current_max <= 0) > + di->current_max = bq27x00_battery_read_imlc(di); > } > > /* Ignore current_now which is a snapshot of the current battery state > @@ -469,6 +504,9 @@ static int bq27x00_battery_get_property( > case POWER_SUPPLY_PROP_CURRENT_NOW: > ret = bq27x00_battery_current(di, val); > break; > + case POWER_SUPPLY_PROP_CURRENT_MAX: > + ret = bq27x00_simple_value(di->current_max, val); > + break; > case POWER_SUPPLY_PROP_CAPACITY: > ret = bq27x00_simple_value(di->cache.capacity, val); > break; > >
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