drivers: adc: comp: refactor to support power domains and pin ret

The ADC did not implement a PM device structure, this PM could not
resume its power domains. Additionally, the ADC and COMP on the
nrf54h20 both have all of their analog inputs routed to pads in
different power domains than themselves, this means the device
drivers for both of them need to request the pads to be resumed.

To keep the drivers simple, we can rely on HW to keep the power
domain the COMP and ADC are in powered, which happens automatically
when the ADC or COMP is ENABLED. We can then replace their power
domains in the devicetree with the one all of their their analog
inputs need, so PM ensures the pads are powered and not retained
when the ADC or COMP is resumed.

Signed-off-by: Bjarki Arge Andreasen <[email protected]>

Author: bjarki-andreasen

drivers/adc/adc_nrfx_saadc.c

@@ -10,6 +10,7 @@
 #include <zephyr/dt-bindings/adc/nrf-saadc-nrf54l.h>
 #include <zephyr/dt-bindings/adc/nrf-saadc-haltium.h>
 #include <zephyr/linker/devicetree_regions.h>
+#include <zephyr/pm/device.h>
 #include <zephyr/logging/log.h>
 #include <zephyr/irq.h>
 #include <dmm.h>
@@ -777,6 +778,11 @@ static void event_handler(const nrfx_saadc_evt_t *event)
 	}
 }
 
+static int saadc_pm_handler(const struct device *dev, enum pm_device_action action)
+{
+	return 0;
+}
+
 static int init_saadc(const struct device *dev)
 {
 	nrfx_err_t err;
@@ -837,5 +843,7 @@ DT_FOREACH_CHILD(DT_DRV_INST(0), VALIDATE_CHANNEL_CONFIG)
 
 NRF_DT_CHECK_NODE_HAS_REQUIRED_MEMORY_REGIONS(DT_DRV_INST(0));
 
-DEVICE_DT_INST_DEFINE(0, init_saadc, NULL, NULL, NULL, POST_KERNEL,
+PM_DEVICE_DT_INST_DEFINE(0, saadc_pm_handler);
+
+DEVICE_DT_INST_DEFINE(0, init_saadc, PM_DEVICE_DT_INST_GET(0), NULL, NULL, POST_KERNEL,
 		      CONFIG_ADC_INIT_PRIORITY, &adc_nrfx_driver_api);

dts/vendor/nordic/nrf54h20.dtsi

@@ -991,7 +991,13 @@
 				interrupts = <386 NRF_DEFAULT_IRQ_PRIORITY>;
 				status = "disabled";
 				#io-channel-cells = <1>;
-				power-domains = <&gdpwr_slow_active>;
+				/*
+				 * This device is actually in the gdpwr_slow_active domain, but all of its
+				 * analog inputs are routed to pads in the gdpwr_slow_main. Request
+				 * gdpwr_slow_main and rely on the device to force its own power domain on
+				 * when active.
+				 */
+				power-domains = <&gdpwr_slow_main>;
 				zephyr,pm-device-runtime-auto;
 			};
 
@@ -1004,6 +1010,12 @@
 				reg = <0x983000 0x1000>;
 				status = "disabled";
 				interrupts = <387 NRF_DEFAULT_IRQ_PRIORITY>;
+				/*
+				 * This device is actually in the gdpwr_slow_active domain, but all of its
+				 * analog inputs are routed to pads in the gdpwr_slow_main. Request
+				 * gdpwr_slow_main and rely on the device to force its own power domain on
+				 * when active.
+				 */
 				power-domains = <&gdpwr_slow_active>;
 			};