[PATCH v8 0/2] TWL6030, TWL6032 GPADC driver

From: Oleksandr Kozaruk
Date: Thu Jul 25 2013 - 09:28:35 EST


v8 - removed unused test channels completely, removed die
temperature channels, as it is not known how to convert ADC code
to temperature. There if formula for twl6030, but no formula
for twl6032.
v7 - addressed clean up comments, removed test channels
v6 - addressed comments about trim bits, checkpatch clean up
v5 - gpadc DT node renamed from "gpadc" to generic "adc", added
temperature channels; raw code is corracted with calibration
v4 - addressed comments: fixed style violation, bug in freeing memory,
added comments explaining calibration method, removed test network
channels from exposing to userspace, error handling for
v3 - fixed compiler warning
v2 - the driver put in drivers/iio, and
converted using iio facilities as suggested by Graeme.

TWL603[02] GPADC is used to measure battery voltage,
battery temperature, battery presence ID, and could
be used to measure twl603[02] die temperature.
This is used on TI blaze, blaze tablet platforms.

The TWL6030/TWL6032 is a PMIC that has a GPADC with 17/19
channels respectively. Some channels have current
source and are used for measuring voltage drop
on resistive load for detecting battery ID resistance,
or measuring voltage drop on NTC resistors for external
temperature measurements, other channels measure voltage,
(i.e. battery voltage), and have inbuilt voltage dividers,
thus, capable to scale voltage. Some channels are dedicated
for measuring die temperature.

Some channels could be calibrated in 2 points, having
offsets from ideal values in trim registers.

The difference between GPADC in TWL6030 and TWL6032:
- 10 bit vs 12 bit ADC;
- 17 vs 19 channels;
- channels have different purpose(i. e. battery voltage
channel 8 vs channel 18);
- trim values are interpreted differently.

The driver is derived from git://git.omapzoom.org/kernel/omap.git
The original driver's authors and contributors are Balaji T K,
Graeme Gregory, Ambresh K, Girish S Ghongdemath.

The changes to the original driver:
- device tree adaptation;
- drop ioctl support - never been used;
- unified measurement method for both devices;
- get rid of "if (device == X)" code style to data driven;
- drop polling end of conversion and use interrupt instead;
- iio framework is used

Tested with on blaze tablet 2 with OMAP4430(twl6030), and
OMAP4470(twl6032) SOMs.

The patches were tested against 3.11-rc2

Oleksandr Kozaruk (2):
ARM: dts: twl: Add GPADC data to device tree
iio: twl6030-gpadc: TWL6030, TWL6032 GPADC driver

arch/arm/boot/dts/twl6030.dtsi | 6 +
drivers/iio/adc/Kconfig | 14 +
drivers/iio/adc/Makefile | 1 +
drivers/iio/adc/twl6030-gpadc.c | 1027 +++++++++++++++++++++++++++++++++++++++
4 files changed, 1048 insertions(+)
create mode 100644 drivers/iio/adc/twl6030-gpadc.c


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