drivers: adc: Add support for gain 2/7 in nRF devices

Extend current adc gains with new entry 2/7.

Signed-off-by: Karol Lasończyk <[email protected]>

Author: kl-cruz

drivers/adc/adc_common.c

@@ -17,6 +17,7 @@ int adc_gain_invert(enum adc_gain gain,
 		[ADC_GAIN_1_6] = {.mul = 6, .div = 1},
 		[ADC_GAIN_1_5] = {.mul = 5, .div = 1},
 		[ADC_GAIN_1_4] = {.mul = 4, .div = 1},
+		[ADC_GAIN_2_7] = {.mul = 7, .div = 2},
 		[ADC_GAIN_1_3] = {.mul = 3, .div = 1},
 		[ADC_GAIN_2_5] = {.mul = 5, .div = 2},
 		[ADC_GAIN_1_2] = {.mul = 2, .div = 1},

drivers/adc/adc_nrfx_saadc.c

@@ -202,6 +202,11 @@ static int adc_nrfx_channel_setup(const struct device *dev,
 		config.gain = NRF_SAADC_GAIN1_4;
 		break;
 #endif
+#if defined(SAADC_CH_CONFIG_GAIN_Gain2_7)
+	case ADC_GAIN_2_7:
+		config.gain = NRF_SAADC_GAIN2_7;
+		break;
+#endif
 #if defined(SAADC_CH_CONFIG_GAIN_Gain1_3) || defined(SAADC_CH_CONFIG_GAIN_Gain2_6)
 	case ADC_GAIN_1_3:
 		config.gain = NRF_SAADC_GAIN1_3;

dts/bindings/adc/adc-controller.yaml

@@ -41,6 +41,7 @@ child-binding:
         - ADC_GAIN_1_6: x 1/6
         - ADC_GAIN_1_5: x 1/5
         - ADC_GAIN_1_4: x 1/4
+        - ADC_GAIN_2_7: x 2/7
         - ADC_GAIN_1_3: x 1/3
         - ADC_GAIN_2_5: x 2/5
         - ADC_GAIN_1_2: x 1/2
@@ -62,6 +63,7 @@ child-binding:
         - "ADC_GAIN_1_6"
         - "ADC_GAIN_1_5"
         - "ADC_GAIN_1_4"
+        - "ADC_GAIN_2_7"
         - "ADC_GAIN_1_3"
         - "ADC_GAIN_2_5"
         - "ADC_GAIN_1_2"

include/zephyr/drivers/adc.h

@@ -35,6 +35,7 @@ enum adc_gain {
 	ADC_GAIN_1_6, /**< x 1/6. */
 	ADC_GAIN_1_5, /**< x 1/5. */
 	ADC_GAIN_1_4, /**< x 1/4. */
+	ADC_GAIN_2_7, /**< x 2/7. */
 	ADC_GAIN_1_3, /**< x 1/3. */
 	ADC_GAIN_2_5, /**< x 2/5. */
 	ADC_GAIN_1_2, /**< x 1/2. */