Messages in this thread Patch in this message | | | From | Philip Rakity <> | Date | Fri, 26 Aug 2011 13:28:22 -0700 | Subject | [PATCH] power: max8925_power: Fix incorrect voltage and current calculation |
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The datasheet indicates a 12 bit value is returned for i2c registers for voltage and current. Code was assuming 8 bits. But default for chip is 12 bit return value.
Voltage is returned in 2mV units -- adjust to return as uV per linux power spec
Adjust current calculation to return units in uA *** NOT POSSIBLE TO VALIDATE THIS since my h/w does not have current hooked up to 8925 *****
Signed-off-by: Philip Rakity <prakity@marvell.com> --- drivers/power/max8925_power.c | 13 ++++++------- 1 files changed, 6 insertions(+), 7 deletions(-)
diff --git a/drivers/power/max8925_power.c b/drivers/power/max8925_power.c index 29b5d2c..5e4e046 100644 --- a/drivers/power/max8925_power.c +++ b/drivers/power/max8925_power.c @@ -190,7 +190,7 @@ static int start_measure(struct max8925_power_info *info, int type) } max8925_bulk_read(info->adc, meas_reg, 2, buf); - ret = (buf[0] << 4) | (buf[1] >> 4); + ret = ((buf[0]<<8) | buf[1]) >> 4; return ret; } @@ -210,7 +210,7 @@ static int max8925_ac_get_prop(struct power_supply *psy, if (info->ac_online) { ret = start_measure(info, MEASURE_VCHG); if (ret >= 0) { - val->intval = ret << 1; /* unit is mV */ + val->intval = ret * 2000; /* unit is uV */ goto out; } } @@ -244,7 +244,7 @@ static int max8925_usb_get_prop(struct power_supply *psy, if (info->usb_online) { ret = start_measure(info, MEASURE_VCHG); if (ret >= 0) { - val->intval = ret << 1; /* unit is mV */ + val->intval = ret * 2000; /* unit is uV */ goto out; } } @@ -268,7 +268,6 @@ static int max8925_bat_get_prop(struct power_supply *psy, union power_supply_propval *val) { struct max8925_power_info *info = dev_get_drvdata(psy->dev->parent); - long long int tmp = 0; int ret = 0; switch (psp) { @@ -279,7 +278,7 @@ static int max8925_bat_get_prop(struct power_supply *psy, if (info->bat_online) { ret = start_measure(info, MEASURE_VMBATT); if (ret >= 0) { - val->intval = ret << 1; /* unit is mV */ + val->intval = ret * 2000; /* unit is uV */ ret = 0; break; } @@ -290,8 +289,8 @@ static int max8925_bat_get_prop(struct power_supply *psy, if (info->bat_online) { ret = start_measure(info, MEASURE_ISNS); if (ret >= 0) { - tmp = (long long int)ret * 6250 / 4096 - 3125; - ret = (int)tmp; + /* assume r_sns is 0.02 */ + ret = ((ret * 6250) - 3125) /* uA */; val->intval = 0; if (ret > 0) val->intval = ret; /* unit is mA */ -- 1.7.6
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