mfd: Refactor ab8500 GPADC API, add raw access

Refactor the GPADC interface to avoid bugs in calling code:

- ab8500_gpadc_[convert|read_raw|ad_to_voltage] clarifies
  each functions use case, *convert wraps *read_raw, and we
  can access raw ADC values properly.
- Renamed gpadc function arguments from "input" to "channel" to
  clarify use, so we don't get confused again.

Signed-off-by: Kalle Komierowski <kalle.komierowski@stericsson.com>
Reviewed-by: Mattias Wallin <mattias.wallin@stericsson.com>
Reviewed-by: John Beckett <john.beckett@stericsson.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
diff --git a/include/linux/mfd/ab8500/gpadc.h b/include/linux/mfd/ab8500/gpadc.h
index 46b9540..2529667 100644
--- a/include/linux/mfd/ab8500/gpadc.h
+++ b/include/linux/mfd/ab8500/gpadc.h
@@ -27,6 +27,9 @@
 struct ab8500_gpadc;
 
 struct ab8500_gpadc *ab8500_gpadc_get(char *name);
-int ab8500_gpadc_convert(struct ab8500_gpadc *gpadc, u8 input);
+int ab8500_gpadc_convert(struct ab8500_gpadc *gpadc, u8 channel);
+int ab8500_gpadc_read_raw(struct ab8500_gpadc *gpadc, u8 channel);
+int ab8500_gpadc_ad_to_voltage(struct ab8500_gpadc *gpadc,
+    u8 channel, int ad_value);
 
 #endif /* _AB8500_GPADC_H */