[PATCH v4] arm64: dts: qcom: x1e78100-thinkpad-t14s: Add thermal zones for PMICs

[Daniel Lezcano <daniel.lezcano@oss.qualcomm.com>]

The ThinkPad T14s needs thermal mitigation under sustained workloads to
limit temperature rise before thermal shutdown. EC interrupt-driven thermal
monitoring is not yet supported, so use the board temperature sensors
exposed through the PMK8550 VADC to provide mitigation now.

Describe the sensors near DRAM, the fan/heatpipe, the GPU and CPU PMICs,
the charger, the WWAN area and the USB-C ports. The DRAM-area sensor faces
the keyboard, while the fan/heatpipe-area sensor faces the back cover.
These are internal board measurements rather than direct measurements of
the user-contact surfaces.

Use the heatpipe-area sensor for passive mitigation at 57.85 degrees
Celsius, derived from observed platform behaviour with the Windows
balanced power profile. Map the passive trip to all CPUs and the GPU,
with 1 degree Celsius hysteresis and a 500 ms passive polling interval.
Name the trip "backcover-ec-alert" so that the planned EC support can
locate and adjust it.

An earlier approach using staged CPU-cluster throttling did not show a
significant improvement and introduced a latency imbalance between CPU
clusters. Keep a single passive trip to provide timely mitigation.

Add 73 degree Celsius critical shutdown trips for the DRAM-area and
heatpipe-area sensors. Retain these baseline thresholds pending
sensor-specific hardware validation. The reported Windows DRAM threshold
of 115 degrees Celsius has not been established to apply to these VADC
measurements and does not justify changing the shutdown thresholds.

Thermal camera measurements indicate that the readings primarily reflect
internal temperatures rather than chassis surface temperatures. No unsafe
external surface temperature was observed during those tests, but they do
not establish qualified critical limits for the internal sensors.

Expose the remaining sensors as monitoring-only zones and enable ADC
threshold monitoring on the corresponding PMK8550 VADC channels.

Reviewed-by: Hans de Goede <johannes.goede@oss.qualcomm.com>
Link: https://patch.msgid.link/20261014193524.5590-1-daniel.lezcano@oss.qualcomm.com
Signed-off-by: Daniel Lezcano <daniel.lezcano@oss.qualcomm.com>
---
 .../qcom/x1e78100-lenovo-thinkpad-t14s.dtsi   | 112 ++++++++++++++++++
 1 file changed, 112 insertions(+)

diff --git a/arch/arm64/boot/dts/qcom/x1e78100-lenovo-thinkpad-t14s.dtsi b/arch/arm64/boot/dts/qcom/x1e78100-lenovo-thinkpad-t14s.dtsi
index 75ad74bcb042..21f4569068e1 100644
--- a/arch/arm64/boot/dts/qcom/x1e78100-lenovo-thinkpad-t14s.dtsi
+++ b/arch/arm64/boot/dts/qcom/x1e78100-lenovo-thinkpad-t14s.dtsi
@@ -502,6 +502,88 @@ platform {
 			};
 		};
 	};
+
+	thermal-zones {
+		/* Sensor near DRAM, facing the keyboard. */
+		dram-thermal {
+			critical-action = "shutdown";
+			thermal-sensors = <&pmk8550_vadc ADC5_GEN3_AMUX1_THM_100K_PU(1)>;
+
+			trips {
+				dram-critical {
+					temperature = <73000>;
+					hysteresis = <1000>;
+					type = "critical";
+				};
+			};
+		};
+
+		/* Sensor near the GPU PMICs. */
+		gpu-pmic-thermal {
+			thermal-sensors = <&pmk8550_vadc ADC5_GEN3_AMUX4_THM_100K_PU(1)>;
+		};
+
+		/* Sensor near the fan/heatpipe, facing the back cover. */
+		heatpipe-thermal {
+			critical-action = "shutdown";
+			polling-delay-passive = <500>;
+
+			thermal-sensors = <&pmk8550_vadc ADC5_GEN3_AMUX2_GPIO_100K_PU(1)>;
+
+			trips {
+				backcover_ec_alert: backcover-ec-alert {
+					temperature = <57850>;
+					hysteresis = <1000>;
+					type = "passive";
+				};
+
+				heatpipe-critical {
+					temperature = <73000>;
+					hysteresis = <1000>;
+					type = "critical";
+				};
+			};
+
+			cooling-maps {
+				map0 {
+					trip = <&backcover_ec_alert>;
+					cooling-device = <&cpu0 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>,
+							 <&cpu1 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>,
+							 <&cpu2 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>,
+							 <&cpu3 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>,
+							 <&cpu4 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>,
+							 <&cpu5 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>,
+							 <&cpu6 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>,
+							 <&cpu7 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>,
+							 <&cpu8 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>,
+							 <&cpu9 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>,
+							 <&cpu10 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>,
+							 <&cpu11 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>,
+							 <&gpu THERMAL_NO_LIMIT THERMAL_NO_LIMIT>;
+				};
+			};
+		};
+
+		/* Sensor in the WWAN area. */
+		wwan-thermal {
+			thermal-sensors = <&pmk8550_vadc ADC5_GEN3_AMUX3_THM_100K_PU(1)>;
+		};
+
+		/* Sensor in the charger area. */
+		charger-thermal {
+			thermal-sensors = <&pmk8550_vadc ADC5_GEN3_AMUX2_THM_100K_PU(1)>;
+		};
+
+		/* Sensor near the CPU PMICs. */
+		cpu-pmic-thermal {
+			thermal-sensors = <&pmk8550_vadc ADC5_GEN3_AMUX1_GPIO_100K_PU(1)>;
+		};
+
+		/* Sensor near the USB-C ports. */
+		typec-thermal {
+			thermal-sensors = <&pmk8550_vadc ADC5_GEN3_AMUX5_THM_100K_PU(1)>;
+		};
+	};
 };
 
 &apps_rsc {
@@ -1285,6 +1367,36 @@ usb0_pwr_1p15_reg_en: usb0-pwr-1p15-reg-en-state {
 	};
 };
 
+&pmk8550_vadc {
+	channel@144 {
+		qcom,adc-tm;
+	};
+
+	channel@145 {
+		qcom,adc-tm;
+	};
+
+	channel@146 {
+		qcom,adc-tm;
+	};
+
+	channel@147 {
+		qcom,adc-tm;
+	};
+
+	channel@148 {
+		qcom,adc-tm;
+	};
+
+	channel@14a {
+		qcom,adc-tm;
+	};
+
+	channel@14b {
+		qcom,adc-tm;
+	};
+};
+
 &qupv3_0 {
 	status = "okay";
 };
-- 
2.53.0