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>

drivers/mfd/ab8500-gpadc.c

@@ -143,12 +143,15 @@ struct ab8500_gpadc *ab8500_gpadc_get(char *name)
 }
 EXPORT_SYMBOL(ab8500_gpadc_get);
 
-static int ab8500_gpadc_ad_to_voltage(struct ab8500_gpadc *gpadc, u8 input,
+/**
+ * ab8500_gpadc_ad_to_voltage() - Convert a raw ADC value to a voltage
+ */
+int ab8500_gpadc_ad_to_voltage(struct ab8500_gpadc *gpadc, u8 channel,
 	int ad_value)
 {
 	int res;
 
-	switch (input) {
+	switch (channel) {
 	case MAIN_CHARGER_V:
 		/* For some reason we don't have calibrated data */
 		if (!gpadc->cal_data[ADC_INPUT_VMAIN].gain) {
@@ -232,18 +235,46 @@ static int ab8500_gpadc_ad_to_voltage(struct ab8500_gpadc *gpadc, u8 input,
 	}
 	return res;
 }
+EXPORT_SYMBOL(ab8500_gpadc_ad_to_voltage);
 
 /**
  * ab8500_gpadc_convert() - gpadc conversion
- * @input:	analog input to be converted to digital data
+ * @channel:	analog channel to be converted to digital data
  *
  * This function converts the selected analog i/p to digital
  * data.
  */
-int ab8500_gpadc_convert(struct ab8500_gpadc *gpadc, u8 input)
+int ab8500_gpadc_convert(struct ab8500_gpadc *gpadc, u8 channel)
+{
+	int ad_value;
+	int voltage;
+
+	ad_value = ab8500_gpadc_read_raw(gpadc, channel);
+	if (ad_value < 0) {
+		dev_err(gpadc->dev, "GPADC raw value failed ch: %d\n", channel);
+		return ad_value;
+	}
+
+	voltage = ab8500_gpadc_ad_to_voltage(gpadc, channel, ad_value);
+
+	if (voltage < 0)
+		dev_err(gpadc->dev, "GPADC to voltage conversion failed ch:"
+			" %d AD: 0x%x\n", channel, ad_value);
+
+	return voltage;
+}
+EXPORT_SYMBOL(ab8500_gpadc_convert);
+
+/**
+ * ab8500_gpadc_read_raw() - gpadc read
+ * @channel:	analog channel to be read
+ *
+ * This function obtains the raw ADC value, this then needs
+ * to be converted by calling ab8500_gpadc_ad_to_voltage()
+ */
+int ab8500_gpadc_read_raw(struct ab8500_gpadc *gpadc, u8 channel)
 {
 	int ret;
-	u16 data = 0;
 	int looplimit = 0;
 	u8 val, low_data, high_data;
 
@@ -278,9 +309,9 @@ int ab8500_gpadc_convert(struct ab8500_gpadc *gpadc, u8 input)
 		goto out;
 	}
 
-	/* Select the input source and set average samples to 16 */
+	/* Select the channel source and set average samples to 16 */
 	ret = abx500_set_register_interruptible(gpadc->dev, AB8500_GPADC,
-		AB8500_GPADC_CTRL2_REG, (input | SW_AVG_16));
+		AB8500_GPADC_CTRL2_REG, (channel | SW_AVG_16));
 	if (ret < 0) {
 		dev_err(gpadc->dev,
 			"gpadc_conversion: set avg samples failed\n");
@@ -292,7 +323,7 @@ int ab8500_gpadc_convert(struct ab8500_gpadc *gpadc, u8 input)
 	 * charging current sense if it needed, ABB 3.0 needs some special
 	 * treatment too.
 	 */
-	switch (input) {
+	switch (channel) {
 	case MAIN_CHARGER_C:
 	case USB_CHARGER_C:
 		ret = abx500_mask_and_set_register_interruptible(gpadc->dev,
@@ -359,7 +390,6 @@ int ab8500_gpadc_convert(struct ab8500_gpadc *gpadc, u8 input)
 		goto out;
 	}
 
-	data = (high_data << 8) | low_data;
 	/* Disable GPADC */
 	ret = abx500_set_register_interruptible(gpadc->dev, AB8500_GPADC,
 		AB8500_GPADC_CTRL1_REG, DIS_GPADC);
@@ -370,8 +400,8 @@ int ab8500_gpadc_convert(struct ab8500_gpadc *gpadc, u8 input)
 	/* Disable VTVout LDO this is required for GPADC */
 	regulator_disable(gpadc->regu);
 	mutex_unlock(&gpadc->ab8500_gpadc_lock);
-	ret = ab8500_gpadc_ad_to_voltage(gpadc, input, data);
-	return ret;
+
+	return (high_data << 8) | low_data;
 
 out:
 	/*
@@ -385,10 +415,10 @@ out:
 	regulator_disable(gpadc->regu);
 	mutex_unlock(&gpadc->ab8500_gpadc_lock);
 	dev_err(gpadc->dev,
-		"gpadc_conversion: Failed to AD convert channel %d\n", input);
+		"gpadc_conversion: Failed to AD convert channel %d\n", channel);
 	return ret;
 }
-EXPORT_SYMBOL(ab8500_gpadc_convert);
+EXPORT_SYMBOL(ab8500_gpadc_read_raw);
 
 /**
  * ab8500_bm_gpswadcconvend_handler() - isr for s/w gpadc conversion completion

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 */