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twl4030_charger: split uA calculation into a function. 

We will need this calculation in other places, so
create functions to map between register value and uA value.

Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: NeilBrown <neil@brown.name>
Signed-off-by: Sebastian Reichel <sre@kernel.org>
This commit is contained in:
NeilBrown 2015-07-30 10:11:24 +10:00 committed by Sebastian Reichel
parent 6e37ec8c77
commit 3b542f089d
1 changed files with 35 additions and 13 deletions
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48
drivers/power/twl4030_charger.c
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@ -177,6 +177,40 @@ static int twl4030_is_battery_present(struct twl4030_bci *bci)
return -ENODEV;
}
/*
* TI provided formulas:
* CGAIN == 0: ICHG = (BCIICHG * 1.7) / (2^10 - 1) - 0.85
* CGAIN == 1: ICHG = (BCIICHG * 3.4) / (2^10 - 1) - 1.7
* Here we use integer approximation of:
* CGAIN == 0: val * 1.6618 - 0.85 * 1000
* CGAIN == 1: (val * 1.6618 - 0.85 * 1000) * 2
*/
/*
* convert twl register value for currents into uA
*/
static int regval2ua(int regval, bool cgain)
{
if (cgain)
return (regval * 16618 - 8500 * 1000) / 5;
else
return (regval * 16618 - 8500 * 1000) / 10;
}
/*
* convert uA currents into twl register value
*/
static int ua2regval(int ua, bool cgain)
{
int ret;
if (cgain)
ua /= 2;
ret = (ua * 10 + 8500 * 1000) / 16618;
/* rounding problems */
if (ret < 512)
ret = 512;
return ret;
}
/*
* Enable/Disable USB Charge functionality.
*/
@ -366,14 +400,6 @@ static int twl4030_bci_usb_ncb(struct notifier_block *nb, unsigned long val,
return NOTIFY_OK;
}
/*
* TI provided formulas:
* CGAIN == 0: ICHG = (BCIICHG * 1.7) / (2^10 - 1) - 0.85
* CGAIN == 1: ICHG = (BCIICHG * 3.4) / (2^10 - 1) - 1.7
* Here we use integer approximation of:
* CGAIN == 0: val * 1.6618 - 0.85
* CGAIN == 1: (val * 1.6618 - 0.85) * 2
*/
static int twl4030_charger_get_current(void)
{
int curr;
@ -388,11 +414,7 @@ static int twl4030_charger_get_current(void)
if (ret)
return ret;
ret = (curr * 16618 - 850 * 10000) / 10;
if (bcictl1 & TWL4030_CGAIN)
ret *= 2;
return ret;
return regval2ua(curr, bcictl1 & TWL4030_CGAIN);
}
/*