drivers: adc: ad7124: Add burnout current source support

Add support for burnout sources in the devicetree and
adc configuration structure.
Implement the burnout current source for the adi,ad7124.

Signed-off-by: Florin Berger <florin@fam-berger.ch>

Author: moiflo033

drivers/adc/Kconfig

@@ -38,6 +38,11 @@ config ADC_CONFIGURABLE_EXCITATION_CURRENT_SOURCE_PIN
 config ADC_CONFIGURABLE_VBIAS_PIN
 	bool
 
+# By selecting or not this option particular ADC drivers indicate if they
+# support configurable burnout current sources
+config ADC_CONFIGURABLE_BURNOUT_SOURCE
+	bool
+
 config ADC_ASYNC
 	bool "Asynchronous call support"
 	select POLL

drivers/adc/Kconfig.ad7124

@@ -9,6 +9,7 @@ config ADC_AD7124
 	select CRC
 	select ADC_CONFIGURABLE_INPUTS
 	select ADC_CONFIGURABLE_EXCITATION_CURRENT_SOURCE_PIN
+	select ADC_CONFIGURABLE_BURNOUT_SOURCE
 	help
 	  Enable the ad7124 adc
 

drivers/adc/adc_ad7124.c

@@ -136,6 +136,9 @@ LOG_MODULE_REGISTER(adc_ad7124, CONFIG_ADC_LOG_LEVEL);
 /* Error register bits */
 #define AD7124_ERR_REG_SPI_IGNORE_ERR BIT(6)
 
+/* Burnout current source configuration bits */
+#define AD7124_BURNOUT_CURRENT_SOURCE_MSK GENMASK(10, 9)
+
 enum ad7124_register_lengths {
 	AD7124_STATUS_REG_LEN = 1,
 	AD7124_ADC_CONTROL_REG_LEN = 2,
@@ -232,6 +235,13 @@ enum ad7124_iout_channel {
 	AD7124_IOUT_AIN7 = 15,
 };
 
+enum ad7124_burnout_current_strength {
+	AD7124_BURNOUT_OFF = 0,
+	AD7124_BURNOUT_0_5_UA = 1,
+	AD7124_BURNOUT_2_UA = 2,
+	AD7124_BURNOUT_4_UA = 3
+};
+
 struct ad7124_current_source_config {
 	enum ad7124_iout_current current;
 	enum ad7124_iout_channel channel;
@@ -241,6 +251,7 @@ struct ad7124_config_props {
 	enum ad7124_reference_source refsel;
 	enum ad7124_gain pga_bits;
 	enum ad7124_filter_type filter_type;
+	enum ad7124_burnout_current_strength burnout_strength;
 	uint16_t odr_sel_bits;
 	bool bipolar;
 	bool inbuf_enable;
@@ -464,6 +475,7 @@ static int adc_ad7124_create_new_cfg(const struct device *dev, const struct adc_
 		new_cfg->props.filter_type = AD7124_FILTER_SINC4;
 	}
 
+	new_cfg->props.burnout_strength = cfg->burnout_source_strength;
 	new_cfg->props.odr_sel_bits = adc_ad7124_odr_to_fs(dev, odr);
 	new_cfg->props.bipolar = config->bipolar_mask & BIT(cfg->channel_id);
 	new_cfg->props.inbuf_enable = config->inbuf_enable_mask & BIT(cfg->channel_id);
@@ -725,6 +737,8 @@ static int adc_ad7124_setup_cfg(const struct device *dev, const struct ad7124_ch
 
 	configuration_setup |= FIELD_PREP(AD7124_SETUP_CONF_REG_REF_SEL_MSK, cfg->props.refsel);
 	configuration_setup |= FIELD_PREP(AD7124_SETUP_CONF_PGA_MSK, cfg->props.pga_bits);
+	configuration_setup |=
+		FIELD_PREP(AD7124_BURNOUT_CURRENT_SOURCE_MSK, cfg->props.burnout_strength);
 	configuration_mask |= AD7124_SETUP_CONFIGURATION_MASK;
 
 	ret = adc_ad7124_reg_write_msk(dev, AD7124_CONFIG(cfg->cfg_slot), AD7124_CONFIG_REG_LEN,

dts/bindings/adc/adc-controller.yaml

@@ -169,3 +169,10 @@ child-binding:
         Output pin selection for the bias voltage. The actual interpretation
         depends on the driver. This is used only for drivers which select
         the ADC_CONFIGURABLE_VBIAS_PIN Kconfig option.
+
+    zephyr,burnout-source-strength:
+      type: int
+      description: |
+        Selection of burnout current source strength. The actual interpretation
+        depends on the driver. This is used only for drivers which select the
+        ADC_CONFIGURABLE_BURNOUT_SOURCE Kconfig option.

include/zephyr/drivers/adc.h

@@ -196,6 +196,16 @@ struct adc_channel_cfg {
 	 */
 	uint32_t vbias_pins;
 #endif /* CONFIG_ADC_CONFIGURABLE_VBIAS_PIN */
+
+#ifdef CONFIG_ADC_CONFIGURABLE_BURNOUT_SOURCE
+	/**
+	 * Drive strength for burnout sources.
+	 * This is only available if the driver enables the feature
+	 * via the hidden configuration option ADC_CONFIGURABLE_BURNOUT_SOURCE.
+	 * The interpretation of this field is dependent on the driver.
+	 */
+	uint8_t burnout_source_strength;
+#endif /* CONFIG_ADC_CONFIGURABLE_BURNOUT_SOURCE */
 };
 
 /**

include/zephyr/dt-bindings/adc/ad7124-adc.h

@@ -66,4 +66,9 @@
 #define AD7124_IOUT_CH_AIN6 0E
 #define AD7124_IOUT_CH_AIN7 0F
 
+#define AD7124_BURNOUT_OFF    00
+#define AD7124_BURNOUT_0_5_UA 01
+#define AD7124_BURNOUT_2_UA   02
+#define AD7124_BURNOUT_4_UA   03
+
 #endif /* ZEPHYR_INCLUDE_DT_BINDINGS_AD7124_ADC_H_ */