diff mbox

[06/15] twl4030_charger: split uA calculation into a function.

Message ID 20150224043351.4243.86053.stgit@notabene.brown (mailing list archive)
State New, archived
Headers show

Commit Message

NeilBrown Feb. 24, 2015, 4:33 a.m. UTC 
We will need this calculation in other places, so
create functions to map between register value and uA value.

Signed-off-by: NeilBrown <neilb@suse.de>
---
 drivers/power/twl4030_charger.c |   48 ++++++++++++++++++++++++++++-----------
 1 file changed, 35 insertions(+), 13 deletions(-)



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Comments

Pavel Machek March 2, 2015, 9:05 p.m. UTC | #1 
On Tue 2015-02-24 15:33:51, NeilBrown wrote:
> We will need this calculation in other places, so
> create functions to map between register value and uA value.
> 
> Signed-off-by: NeilBrown <neilb@suse.de>

Acked-by: Pavel Machek <pavel@ucw.cz>

> +static int regval2ua(int regval, bool cgain)
> +{
> +	if (cgain)
> +		return (regval * 16618 - 8500 * 1000) / 5;
> +	else
> +		return (regval * 16618 - 8500 * 1000) / 10;
> +}

   int res = (regval * 16618 - 8500 * 1000);
   if (cgain)
      return res / 5;
   return res / 10;

?
									Pavel
NeilBrown March 4, 2015, 9:20 a.m. UTC | #2 
On Mon, 2 Mar 2015 22:05:18 +0100 Pavel Machek <pavel@ucw.cz> wrote:

> On Tue 2015-02-24 15:33:51, NeilBrown wrote:
> > We will need this calculation in other places, so
> > create functions to map between register value and uA value.
> > 
> > Signed-off-by: NeilBrown <neilb@suse.de>
> 
> Acked-by: Pavel Machek <pavel@ucw.cz>

Thanks.


> 
> > +static int regval2ua(int regval, bool cgain)
> > +{
> > +	if (cgain)
> > +		return (regval * 16618 - 8500 * 1000) / 5;
> > +	else
> > +		return (regval * 16618 - 8500 * 1000) / 10;
> > +}
> 
>    int res = (regval * 16618 - 8500 * 1000);
>    if (cgain)
>       return res / 5;
>    return res / 10;
> 
> ?
> 									Pavel

Maybe ... not sure it is really more readable.  I think I'll leave it as is.

Thanks,
NeilBrown
diff mbox

Patch

diff --git a/drivers/power/twl4030_charger.c b/drivers/power/twl4030_charger.c
index db8931a17541..0b6fb06a0c01 100644
--- a/drivers/power/twl4030_charger.c
+++ b/drivers/power/twl4030_charger.c
@@ -178,6 +178,40 @@  static int twl4030_is_battery_present(struct twl4030_bci *bci)
 }
 
 /*
+ * 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.
  */
 static int twl4030_charger_enable_usb(struct twl4030_bci *bci, bool enable)
@@ -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);
 }
 
 /*