drivers: adc: sam0: Fix adc_reference implementation

The current sam0 adc driver not implement correctly the adc_reference
enum values. This try homonize adc input referece by tracking VDDANA
at ADC_REF_VDD_1. The ADC_REF_VDD_1_2 were fixed with correct INTVCCx
channel selection.

Fixes #45443

Signed-off-by: Gerson Fernando Budke <[email protected]>

Author: nandojve

drivers/adc/adc_sam0.c

@@ -133,7 +133,6 @@ static int adc_sam0_channel_setup(const struct device *dev,
 	adc->SAMPCTRL.reg = sampctrl;
 	wait_synchronization(adc);
 
-
 	uint8_t refctrl;
 
 	switch (channel_cfg->reference) {
@@ -142,14 +141,14 @@ static int adc_sam0_channel_setup(const struct device *dev,
 		/* Enable the internal bandgap reference */
 		ADC_BGEN = 1;
 		break;
-	case ADC_REF_VDD_1_2:
-		refctrl = ADC_REFCTRL_REFSEL_VDD_1_2 | ADC_REFCTRL_REFCOMP;
-		break;
 #ifdef ADC_REFCTRL_REFSEL_VDD_1
 	case ADC_REF_VDD_1:
 		refctrl = ADC_REFCTRL_REFSEL_VDD_1 | ADC_REFCTRL_REFCOMP;
 		break;
 #endif
+	case ADC_REF_VDD_1_2:
+		refctrl = ADC_REFCTRL_REFSEL_VDD_1_2 | ADC_REFCTRL_REFCOMP;
+		break;
 	case ADC_REF_EXTERNAL0:
 		refctrl = ADC_REFCTRL_REFSEL_AREFA;
 		break;

soc/arm/atmel_sam0/common/adc_fixup_sam0.h

@@ -106,6 +106,9 @@
 #endif
 #endif /* MCLK */
 
+/*
+ * All SAM0 define the internal voltage reference as 1.0V by default.
+ */
 #ifndef ADC_REFCTRL_REFSEL_INTERNAL
 #  ifdef ADC_REFCTRL_REFSEL_INTREF
 #    define ADC_REFCTRL_REFSEL_INTERNAL ADC_REFCTRL_REFSEL_INTREF
@@ -114,18 +117,28 @@
 #  endif
 #endif
 
+/*
+ * Some SAM0 devices can use VDDANA as a direct reference. For the devices
+ * that not offer this option, the internal 1.0V reference will be used.
+ */
+#ifndef ADC_REFCTRL_REFSEL_VDD_1
+#  if defined(ADC0_BANDGAP)
+#    define ADC_REFCTRL_REFSEL_VDD_1 ADC_REFCTRL_REFSEL_INTVCC1
+#  elif defined(ADC_REFCTRL_REFSEL_INTVCC2)
+#    define ADC_REFCTRL_REFSEL_VDD_1 ADC_REFCTRL_REFSEL_INTVCC2
+#  endif
+#endif
+
+/*
+ * SAMD/E5x define ADC[0-1]_BANDGAP symbol. Only those devices use INTVCC0 to
+ * implement VDDANA / 2.
+ */
 #ifndef ADC_REFCTRL_REFSEL_VDD_1_2
-#  ifdef ADC_REFCTRL_REFSEL_INTVCC0
+#  ifdef ADC0_BANDGAP
 #    define ADC_REFCTRL_REFSEL_VDD_1_2 ADC_REFCTRL_REFSEL_INTVCC0
 #  else
 #    define ADC_REFCTRL_REFSEL_VDD_1_2 ADC_REFCTRL_REFSEL_INTVCC1
 #  endif
 #endif
 
-#ifndef ADC_REFCTRL_REFSEL_VDD_1
-#  ifdef ADC_REFCTRL_REFSEL_INTVCC1
-#    define ADC_REFCTRL_REFSEL_VDD_1 ADC_REFCTRL_REFSEL_INTVCC1
-#  endif
-#endif
-
 #endif /* _ATMEL_SAM0_ADC_FIXUP_H_ */