zephyr: drivers: add thermistor test suite

Thermistor driver uses ADC to read temperature. Because of that ADC
emulator is added to overlay dts. Thermistor test suite check behaviour
in case of ADC error and test if conversion from ADC output to
temperature is precise.

BUG=b:184857072
BRANCH=none
TEST=run zmake drivers test

Signed-off-by: Tomasz Michalec <tm@semihalf.com>
Change-Id: Icc6c779ce590d2768a382bccfb04acec657a140c
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2886888
Reviewed-by: Simon Glass <sjg@chromium.org>

5 files changed, 565 insertions, 1 deletions

diff --git a/zephyr/test/drivers/gpio_map.h b/zephyr/test/drivers/gpio_map.h
index 4caa2f420d..1f67138bd2 100644
--- a/zephyr/test/drivers/gpio_map.h
+++ b/zephyr/test/drivers/gpio_map.h
@@ -9,6 +9,16 @@
 #include <devicetree.h>
 #include <gpio_signal.h>
 
+/*
+ * Without https://github.com/zephyrproject-rtos/zephyr/pull/29282, we need
+ * to manually link GPIO_ defines that platform/ec code expects to the
+ * enum gpio_signal values that are generated by device tree bindings.
+ *
+ * Note we only need to create aliases for GPIOs that are referenced in common
+ * platform/ec code.
+ */
+#define CONFIG_TEMP_SENSOR_POWER_GPIO GPIO_PG_EC_DSW_PWROK
+
 #define EC_CROS_GPIO_INTERRUPTS                                           \
 	GPIO_INT(GPIO_AC_PRESENT, GPIO_INT_EDGE_BOTH, extpower_interrupt)
 
diff --git a/zephyr/test/drivers/overlay.dts b/zephyr/test/drivers/overlay.dts
index 86cef81435..4190647db4 100644
--- a/zephyr/test/drivers/overlay.dts
+++ b/zephyr/test/drivers/overlay.dts
@@ -29,6 +29,11 @@
 			enum-name = "GPIO_WP_L";
 			label = "WP_L";
 		};
+		pg_ec_dsw_pwrok {
+			gpios = <&gpio0 4 GPIO_INPUT>;
+			enum-name = "GPIO_PG_EC_DSW_PWROK";
+			label = "PG_EC_DSW_PWROK";
+		};
 	};
 	named-i2c-ports {
 		compatible = "named-i2c-ports";
@@ -67,10 +72,91 @@
 			enum-name = "lgc011";
 		};
 	};
+
+	adc0: adc {
+		compatible = "zephyr,adc-emul";
+		nchannels = <4>;
+		ref-internal-mv = <3300>;
+		#io-channel-cells = <1>;
+		label = "ADC_0";
+		status = "okay";
+	};
+
+	named-adc-channels {
+		compatible = "named-adc-channels";
+
+		adc_charger: charger {
+			label = "ADC_TEMP_SENSOR_CHARGER";
+			enum-name = "ADC_TEMP_SENSOR_CHARGER";
+			channel = <0>;
+		};
+		adc_pp3300_regulator: pp3300-regulator {
+			label = "ADC_TEMP_SENSOR_PP3300_REGULATOR";
+			enum-name = "ADC_TEMP_SENSOR_PP3300_REGULATOR";
+			channel = <1>;
+		};
+		adc_ddr_soc: ddr-soc {
+			label = "ADC_TEMP_SENSOR_DDR_SOC";
+			enum-name = "ADC_TEMP_SENSOR_DDR_SOC";
+			channel = <2>;
+		};
+		adc_fan: fan {
+			label = "ADC_TEMP_SENSOR_FAN";
+			enum-name = "ADC_TEMP_SENSOR_FAN";
+			channel = <3>;
+		};
+	};
+
+	named-temp-sensors {
+		charger {
+			compatible = "temp-3v3-13k7-47k-4050b";
+			label = "TEMP_SENSOR_CHARGER";
+			enum-name = "TEMP_SENSOR_CHARGER";
+			temp_fan_off = <40>;
+			temp_fan_max = <55>;
+			temp_host_high = <75>;
+			temp_host_halt = <80>;
+			temp_host_release_high = <65>;
+			adc = <&adc_charger>;
+		};
+		pp3300-regulator {
+			compatible = "temp-3v3-30k9-47k-4050b";
+			label = "TEMP_SENSOR_PP3300_REGULATOR";
+			enum-name = "TEMP_SENSOR_PP3300_REGULATOR";
+			temp_fan_off = <40>;
+			temp_fan_max = <55>;
+			temp_host_high = <75>;
+			temp_host_halt = <80>;
+			temp_host_release_high = <65>;
+			adc = <&adc_pp3300_regulator>;
+		};
+		ddr-soc {
+			compatible = "temp-3v3-51k1-47k-4050b";
+			label = "TEMP_SENSOR_DDR_SOC";
+			enum-name = "TEMP_SENSOR_DDR_SOC";
+			temp_fan_off = <35>;
+			temp_fan_max = <50>;
+			temp_host_high = <70>;
+			temp_host_halt = <80>;
+			temp_host_release_high = <65>;
+			adc = <&adc_ddr_soc>;
+		};
+		fan {
+			compatible = "temp-3v0-22k6-47k-4050b";
+			label = "TEMP_SENSOR_FAN";
+			enum-name = "TEMP_SENSOR_FAN";
+			temp_fan_off = <35>;
+			temp_fan_max = <50>;
+			temp_host_high = <70>;
+			temp_host_halt = <80>;
+			temp_host_release_high = <65>;
+			adc = <&adc_fan>;
+		};
+	};
 };
 
 &gpio0 {
-	ngpios = <4>;
+	ngpios = <5>;
 };
 
 &i2c0 {
diff --git a/zephyr/test/drivers/prj.conf b/zephyr/test/drivers/prj.conf
index e9674907e3..4192c23961 100644
--- a/zephyr/test/drivers/prj.conf
+++ b/zephyr/test/drivers/prj.conf
@@ -13,6 +13,9 @@ CONFIG_GPIO=y
 CONFIG_GPIO_EMUL=y
 CONFIG_EMUL_EEPROM_AT2X=y
 CONFIG_EMUL_SMART_BATTERY=y
+CONFIG_ADC=y
+CONFIG_ADC_EMUL=y
+CONFIG_HEAP_MEM_POOL_SIZE=1024
 
 CONFIG_PLATFORM_EC_BATTERY_PRESENT_GPIO=y
 CONFIG_PLATFORM_EC_EXTPOWER_GPIO=y
@@ -36,6 +39,13 @@ CONFIG_PLATFORM_EC_USB_PD_TCPM_TUSB422=y
 CONFIG_PLATFORM_EC_USB_MUX_VIRTUAL=y
 CONFIG_PLATFORM_EC_USBC_PPC_SN5S330=y
 CONFIG_PLATFORM_EC_CBI=y
+CONFIG_PLATFORM_EC_ADC=y
+CONFIG_PLATFORM_EC_TEMP_SENSOR=y
+CONFIG_PLATFORM_EC_THERMISTOR=y
+CONFIG_PLATFORM_EC_STEINHART_HART_3V0_22K6_47K_4050B=y
+CONFIG_PLATFORM_EC_STEINHART_HART_3V3_13K7_47K_4050B=y
+CONFIG_PLATFORM_EC_STEINHART_HART_3V3_30K9_47K_4050B=y
+CONFIG_PLATFORM_EC_STEINHART_HART_3V3_51K1_47K_4050B=y
 
 # Things that default to on, but aren't working yet
 CONFIG_PLATFORM_EC_BACKLIGHT_LID=n
diff --git a/zephyr/test/drivers/src/main.c b/zephyr/test/drivers/src/main.c
index f16dcbd3f1..b047038153 100644
--- a/zephyr/test/drivers/src/main.c
+++ b/zephyr/test/drivers/src/main.c
@@ -10,6 +10,7 @@
 extern void test_suite_battery(void);
 extern void test_suite_cbi(void);
 extern void test_suite_smart_battery(void);
+extern void test_suite_thermistor(void);
 
 void test_main(void)
 {
@@ -21,4 +22,5 @@ void test_main(void)
 	test_suite_battery();
 	test_suite_cbi();
 	test_suite_smart_battery();
+	test_suite_thermistor();
 }
diff --git a/zephyr/test/drivers/src/thermistor.c b/zephyr/test/drivers/src/thermistor.c
new file mode 100644
index 0000000000..621cdfaa68
--- /dev/null
+++ b/zephyr/test/drivers/src/thermistor.c
@@ -0,0 +1,456 @@
+/* Copyright 2021 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include <zephyr.h>
+#include <ztest.h>
+#include <drivers/adc.h>
+#include <drivers/adc/adc_emul.h>
+#include <drivers/gpio.h>
+#include <drivers/gpio/gpio_emul.h>
+
+#include "common.h"
+#include "../driver/temp_sensor/thermistor.h"
+
+
+#define GPIO_PG_EC_DSW_PWROK_PATH DT_PATH(named_gpios, pg_ec_dsw_pwrok)
+#define GPIO_PG_EC_DSW_PWROK_PORT DT_GPIO_PIN(GPIO_PG_EC_DSW_PWROK_PATH, gpios)
+
+#define ADC_DEVICE_NAME		DT_LABEL(DT_NODELABEL(adc0))
+
+#define TEMP_3V3_13K7_47K_4050B_INST	DT_INST(0, temp_3v3_13k7_47k_4050b)
+#define ADC_CHANNEL_3V3_13K7_47K_4050B \
+		DT_PROP(DT_PHANDLE(TEMP_3V3_13K7_47K_4050B_INST, adc), channel)
+
+#define TEMP_3V3_30K9_47K_4050B_INST	DT_INST(0, temp_3v3_30k9_47k_4050b)
+#define ADC_CHANNEL_3V3_30K9_47K_4050B \
+		DT_PROP(DT_PHANDLE(TEMP_3V3_30K9_47K_4050B_INST, adc), channel)
+
+#define TEMP_3V3_51K1_47K_4050B_INST	DT_INST(0, temp_3v3_51k1_47k_4050b)
+#define ADC_CHANNEL_3V3_51K1_47K_4050B \
+		DT_PROP(DT_PHANDLE(TEMP_3V3_51K1_47K_4050B_INST, adc), channel)
+
+#define TEMP_3V0_22K6_47K_4050B_INST	DT_INST(0, temp_3v0_22k6_47k_4050b)
+#define ADC_CHANNEL_3V0_22K6_47K_4050B \
+		DT_PROP(DT_PHANDLE(TEMP_3V0_22K6_47K_4050B_INST, adc), channel)
+
+/* Conversion of temperature doesn't need to be 100% accurate */
+#define TEMP_EPS	2
+
+/**
+ * Test if get temp function return expected error when ADC is not powered
+ * (indicated as GPIO pin set to low) and return success after powering on ADC.
+ */
+static void test_thermistor_power_pin(void)
+{
+	const struct device *gpio_dev =
+		DEVICE_DT_GET(DT_GPIO_CTLR(GPIO_PG_EC_DSW_PWROK_PATH, gpios));
+	const struct device *adc_dev = device_get_binding(ADC_DEVICE_NAME);
+	int temp;
+
+	zassert_not_null(gpio_dev, "Cannot get GPIO device");
+	zassert_not_null(adc_dev, "Cannot get ADC device");
+
+	/* Make sure that ADC return any valid value */
+	zassert_ok(adc_emul_const_value_set(adc_dev,
+					    ADC_CHANNEL_3V3_13K7_47K_4050B,
+					    1000),
+		   "adc_emul_const_value_set() failed");
+	zassert_ok(adc_emul_const_value_set(adc_dev,
+					    ADC_CHANNEL_3V3_30K9_47K_4050B,
+					    1000),
+		   "adc_emul_const_value_set() failed");
+	zassert_ok(adc_emul_const_value_set(adc_dev,
+					    ADC_CHANNEL_3V3_51K1_47K_4050B,
+					    1000),
+		   "adc_emul_const_value_set() failed");
+	zassert_ok(adc_emul_const_value_set(adc_dev,
+					    ADC_CHANNEL_3V0_22K6_47K_4050B,
+					    1000),
+		   "adc_emul_const_value_set() failed");
+
+	/* pg_ec_dsw_pwrok = 0 means ADC is not powered. */
+	zassert_ok(gpio_emul_input_set(gpio_dev, GPIO_PG_EC_DSW_PWROK_PORT, 0),
+		   NULL);
+	zassert_equal(EC_ERROR_NOT_POWERED,
+		      get_temp_3v3_13k7_47k_4050b(
+					ADC_CHANNEL_3V3_13K7_47K_4050B, &temp),
+		      NULL);
+	zassert_equal(EC_ERROR_NOT_POWERED,
+		      get_temp_3v3_30k9_47k_4050b(
+					ADC_CHANNEL_3V3_30K9_47K_4050B, &temp),
+		      NULL);
+	zassert_equal(EC_ERROR_NOT_POWERED,
+		      get_temp_3v3_51k1_47k_4050b(
+					ADC_CHANNEL_3V3_51K1_47K_4050B, &temp),
+		      NULL);
+	zassert_equal(EC_ERROR_NOT_POWERED,
+		      get_temp_3v0_22k6_47k_4050b(
+					ADC_CHANNEL_3V0_22K6_47K_4050B, &temp),
+		      NULL);
+
+	/* pg_ec_dsw_pwrok = 1 means ADC is powered. */
+	zassert_ok(gpio_emul_input_set(gpio_dev, GPIO_PG_EC_DSW_PWROK_PORT, 1),
+		   NULL);
+	zassert_equal(EC_SUCCESS,
+		      get_temp_3v3_13k7_47k_4050b(
+					ADC_CHANNEL_3V3_13K7_47K_4050B, &temp),
+		      NULL);
+	zassert_equal(EC_SUCCESS,
+		      get_temp_3v3_30k9_47k_4050b(
+					ADC_CHANNEL_3V3_30K9_47K_4050B, &temp),
+		      NULL);
+	zassert_equal(EC_SUCCESS,
+		      get_temp_3v3_51k1_47k_4050b(
+					ADC_CHANNEL_3V3_51K1_47K_4050B, &temp),
+		      NULL);
+	zassert_equal(EC_SUCCESS,
+		      get_temp_3v0_22k6_47k_4050b(
+					ADC_CHANNEL_3V0_22K6_47K_4050B, &temp),
+		      NULL);
+
+}
+
+/** Simple ADC emulator custom function which always return error */
+static int adc_error_func(const struct device *dev, unsigned int channel,
+			  void *param, uint32_t *result)
+{
+	return -EINVAL;
+}
+
+/** Test if get temp function return expected error on ADC malfunction */
+static void test_thermistor_adc_read_error(void)
+{
+	const struct device *adc_dev = device_get_binding(ADC_DEVICE_NAME);
+	int temp;
+
+	zassert_not_null(adc_dev, "Cannot get ADC device");
+
+	/* Return error on all ADC channels */
+	zassert_ok(adc_emul_value_func_set(adc_dev,
+					   ADC_CHANNEL_3V3_13K7_47K_4050B,
+					   adc_error_func, NULL),
+		   "adc_emul_value_func_set() failed");
+	zassert_ok(adc_emul_value_func_set(adc_dev,
+					   ADC_CHANNEL_3V3_30K9_47K_4050B,
+					   adc_error_func, NULL),
+		   "adc_emul_value_func_set() failed");
+	zassert_ok(adc_emul_value_func_set(adc_dev,
+					   ADC_CHANNEL_3V3_51K1_47K_4050B,
+					   adc_error_func, NULL),
+		   "adc_emul_value_func_set() failed");
+	zassert_ok(adc_emul_value_func_set(adc_dev,
+					   ADC_CHANNEL_3V0_22K6_47K_4050B,
+					   adc_error_func, NULL),
+		   "adc_emul_value_func_set() failed");
+
+	zassert_equal(EC_ERROR_UNKNOWN,
+		      get_temp_3v3_13k7_47k_4050b(
+					ADC_CHANNEL_3V3_13K7_47K_4050B, &temp),
+		      NULL);
+	zassert_equal(EC_ERROR_UNKNOWN,
+		      get_temp_3v3_30k9_47k_4050b(
+					ADC_CHANNEL_3V3_30K9_47K_4050B, &temp),
+		      NULL);
+	zassert_equal(EC_ERROR_UNKNOWN,
+		      get_temp_3v3_51k1_47k_4050b(
+					ADC_CHANNEL_3V3_51K1_47K_4050B, &temp),
+		      NULL);
+	zassert_equal(EC_ERROR_UNKNOWN,
+		      get_temp_3v0_22k6_47k_4050b(
+					ADC_CHANNEL_3V0_22K6_47K_4050B, &temp),
+		      NULL);
+}
+
+/** Get resistance of thermistor for given temperature */
+static int resistance(int t)
+{
+	/* Thermistor manufacturer resistance lookup table*/
+	int r_table[] = {
+		155700, 147900, 140600, 133700, 127200, /* 0*C  - 4*C */
+		121000, 115100, 109600, 104300, 99310,  /* 5*C  - 9*C */
+		94600,  90130,  85890,  81870,  78070,  /* 10*C - 14*C */
+		74450,  71020,  67770,  64680,  61750,  /* 15*C - 19*C */
+		58970,  56320,  53810,  51430,  49160,  /* 20*C - 24*C */
+		47000,  44950,  42990,  41130,  39360,  /* 25*C - 29*C */
+		37680,  36070,  34540,  33080,  31690,  /* 30*C - 34*C */
+		30360,  29100,  27900,  26750,  25650,  /* 35*C - 39*C */
+		24610,  23610,  22660,  21750,  20880,  /* 40*C - 44*C */
+		20050,  19260,  18500,  17780,  17090,  /* 45*C - 49*C */
+		16430,  15800,  15200,  14620,  14070,  /* 50*C - 54*C */
+		13540,  13030,  12550,  12090,  11640,  /* 55*C - 59*C */
+		11210,  10800,  10410,  10040,  9676,   /* 60*C - 64*C */
+		9331,   8999,   8680,   8374,   8081,   /* 65*C - 69*C */
+		7799,   7528,   7268,   7018,   6777,   /* 70*C - 74*C */
+		6546,   6324,   6111,   5906,   5708,   /* 75*C - 79*C */
+		5518,   5335,   5160,   4990,   4827,   /* 80*C - 84*C */
+		4671,   4519,   4374,   4233,   4098,   /* 85*C - 89*C */
+		3968,   3842,   3721,   3605,   3492,   /* 90*C - 94*C */
+		3384,   3279,   3179,   3082,   2988,   /* 95*C - 99*C */
+		2898                                    /* 100*C */
+	};
+
+	t -= 273;
+	if (t < 0)
+		return r_table[0] + 10000;
+
+	if (t >= ARRAY_SIZE(r_table))
+		return r_table[ARRAY_SIZE(r_table) - 1] - 100;
+
+	return r_table[t];
+}
+
+/**
+ * Calculate output voltage in voltage divider circuit using formula
+ * Vout = Vs * r2 / (r1 + r2)
+ */
+static int volt_divider(int vs, int r1, int r2)
+{
+	return vs * r2 / (r1 + r2);
+}
+
+struct thermistor_state {
+	const int v;
+	const int r;
+	int temp_expected;
+};
+
+/** ADC emulator function which calculate output voltage for given thermistor */
+static int adc_temperature_func(const struct device *dev, unsigned int channel,
+				void *param, uint32_t *result)
+{
+	struct thermistor_state *s = (struct thermistor_state *)param;
+
+	*result = volt_divider(s->v, s->r, resistance(s->temp_expected));
+
+	return 0;
+}
+
+/** Test conversion from ADC raw value to temperature */
+static void test_thermistor_3v3_13k7_47k_4050b(void)
+{
+	const struct device *adc_dev = device_get_binding(ADC_DEVICE_NAME);
+	struct thermistor_state state = {
+		.v = 3300,
+		.r = 13700,
+	};
+	int temp_expected;
+	int temp;
+
+	zassert_not_null(adc_dev, "Cannot get ADC device");
+
+	/* Setup ADC channel */
+	zassert_ok(adc_emul_value_func_set(adc_dev,
+					   ADC_CHANNEL_3V3_13K7_47K_4050B,
+					   adc_temperature_func, &state),
+		   "adc_emul_value_func_set() failed");
+
+	/* Makes sure that reference voltage is correct for given thermistor */
+	zassert_ok(adc_emul_ref_voltage_set(adc_dev, ADC_REF_INTERNAL, state.v),
+		   "adc_emul_ref_voltage_set() failed");
+
+	/* Test whole supported range from 0*C to 100*C (273*K to 373*K) */
+	for (temp_expected = 273; temp_expected <= 373; temp_expected++) {
+		state.temp_expected = temp_expected;
+		zassert_equal(EC_SUCCESS,
+			      get_temp_3v3_13k7_47k_4050b(
+					ADC_CHANNEL_3V3_13K7_47K_4050B, &temp),
+			      NULL);
+		zassert_within(temp_expected, temp, TEMP_EPS,
+			       "Expected %d*K, got %d*K", temp_expected, temp);
+	}
+
+	/* Temperatures below 0*C should be reported as 0*C */
+	state.temp_expected = -15 + 273;
+	zassert_equal(EC_SUCCESS,
+		      get_temp_3v3_13k7_47k_4050b(
+				ADC_CHANNEL_3V3_13K7_47K_4050B, &temp),
+		      NULL);
+	zassert_equal(273, temp, "Expected %d*K, got %d*K", 273, temp);
+
+	/* Temperatures above 100*C should be reported as 100*C */
+	state.temp_expected = 115 + 273;
+	zassert_equal(EC_SUCCESS,
+		      get_temp_3v3_13k7_47k_4050b(
+				ADC_CHANNEL_3V3_13K7_47K_4050B, &temp),
+		      NULL);
+	zassert_equal(373, temp, "Expected %d*K, got %d*K", 373, temp);
+}
+
+/** Test conversion from ADC raw value to temperature */
+static void test_thermistor_3v3_30k9_47k_4050b(void)
+{
+	const struct device *adc_dev = device_get_binding(ADC_DEVICE_NAME);
+	struct thermistor_state state = {
+		.v = 3300,
+		.r = 30900,
+	};
+	int temp_expected;
+	int temp;
+
+	zassert_not_null(adc_dev, "Cannot get ADC device");
+
+	/* Setup ADC channel */
+	zassert_ok(adc_emul_value_func_set(adc_dev,
+					   ADC_CHANNEL_3V3_30K9_47K_4050B,
+					   adc_temperature_func, &state),
+		   "adc_emul_value_func_set() failed");
+
+	/* Makes sure that reference voltage is correct for given thermistor */
+	zassert_ok(adc_emul_ref_voltage_set(adc_dev, ADC_REF_INTERNAL, state.v),
+		   "adc_emul_ref_voltage_set() failed");
+
+	/* Test whole supported range from 0*C to 100*C (273*K to 373*K) */
+	for (temp_expected = 273; temp_expected <= 373; temp_expected++) {
+		state.temp_expected = temp_expected;
+		zassert_equal(EC_SUCCESS,
+			      get_temp_3v3_30k9_47k_4050b(
+					ADC_CHANNEL_3V3_30K9_47K_4050B, &temp),
+			      NULL);
+		zassert_within(temp_expected, temp, TEMP_EPS,
+			       "Expected %d*K, got %d*K", temp_expected, temp);
+	}
+
+	/* Temperatures below 0*C should be reported as 0*C */
+	state.temp_expected = -15 + 273;
+	zassert_equal(EC_SUCCESS,
+		      get_temp_3v3_30k9_47k_4050b(
+				ADC_CHANNEL_3V3_30K9_47K_4050B, &temp),
+		      NULL);
+	zassert_equal(273, temp, "Expected %d*K, got %d*K", 273, temp);
+
+	/* Temperatures above 100*C should be reported as 100*C */
+	state.temp_expected = 115 + 273;
+	zassert_equal(EC_SUCCESS,
+		      get_temp_3v3_30k9_47k_4050b(
+				ADC_CHANNEL_3V3_30K9_47K_4050B, &temp),
+		      NULL);
+	zassert_equal(373, temp, "Expected %d*K, got %d*K", 373, temp);
+}
+
+/** Test conversion from ADC raw value to temperature */
+static void test_thermistor_3v3_51k1_47k_4050b(void)
+{
+	const struct device *adc_dev = device_get_binding(ADC_DEVICE_NAME);
+	struct thermistor_state state = {
+		.v = 3300,
+		.r = 51100,
+	};
+	int temp_expected;
+	int temp;
+
+	zassert_not_null(adc_dev, "Cannot get ADC device");
+
+	/* Setup ADC channel */
+	zassert_ok(adc_emul_value_func_set(adc_dev,
+					   ADC_CHANNEL_3V3_51K1_47K_4050B,
+					   adc_temperature_func, &state),
+		   "adc_emul_value_func_set() failed");
+
+	/* Makes sure that reference voltage is correct for given thermistor */
+	zassert_ok(adc_emul_ref_voltage_set(adc_dev, ADC_REF_INTERNAL, state.v),
+		   "adc_emul_ref_voltage_set() failed");
+
+	/* Test whole supported range from 0*C to 100*C (273*K to 373*K) */
+	for (temp_expected = 273; temp_expected <= 373; temp_expected++) {
+		state.temp_expected = temp_expected;
+		zassert_equal(EC_SUCCESS,
+			      get_temp_3v3_51k1_47k_4050b(
+					ADC_CHANNEL_3V3_51K1_47K_4050B, &temp),
+			      NULL);
+		zassert_within(temp_expected, temp, TEMP_EPS,
+			       "Expected %d*K, got %d*K", temp_expected, temp);
+	}
+
+	/* Temperatures below 0*C should be reported as 0*C */
+	state.temp_expected = -15 + 273;
+	zassert_equal(EC_SUCCESS,
+		      get_temp_3v3_51k1_47k_4050b(
+				ADC_CHANNEL_3V3_51K1_47K_4050B, &temp),
+		      NULL);
+	zassert_equal(273, temp, "Expected %d*K, got %d*K", 273, temp);
+
+	/* Temperatures above 100*C should be reported as 100*C */
+	state.temp_expected = 115 + 273;
+	zassert_equal(EC_SUCCESS,
+		      get_temp_3v3_51k1_47k_4050b(
+				ADC_CHANNEL_3V3_51K1_47K_4050B, &temp),
+		      NULL);
+	zassert_equal(373, temp, "Expected %d*K, got %d*K", 373, temp);
+}
+
+/** Test conversion from ADC raw value to temperature */
+static void test_thermistor_3v0_22k6_47k_4050b(void)
+{
+	const struct device *adc_dev = device_get_binding(ADC_DEVICE_NAME);
+	struct thermistor_state state = {
+		.v = 3000,
+		.r = 22600,
+	};
+	int temp_expected;
+	int temp;
+
+	zassert_not_null(adc_dev, "Cannot get ADC device");
+
+	/* Setup ADC channel */
+	zassert_ok(adc_emul_value_func_set(adc_dev,
+					   ADC_CHANNEL_3V0_22K6_47K_4050B,
+					   adc_temperature_func, &state),
+		   "adc_emul_value_func_set() failed");
+
+	/* Makes sure that reference voltage is correct for given thermistor */
+	zassert_ok(adc_emul_ref_voltage_set(adc_dev, ADC_REF_INTERNAL, state.v),
+		   "adc_emul_ref_voltage_set() failed");
+
+	/* Test whole supported range from 0*C to 100*C (273*K to 373*K) */
+	for (temp_expected = 273; temp_expected <= 373; temp_expected++) {
+		state.temp_expected = temp_expected;
+		zassert_equal(EC_SUCCESS,
+			      get_temp_3v0_22k6_47k_4050b(
+					ADC_CHANNEL_3V0_22K6_47K_4050B, &temp),
+			      NULL);
+		zassert_within(temp_expected, temp, TEMP_EPS,
+			       "Expected %d*K, got %d*K", temp_expected, temp);
+	}
+
+	/* Temperatures below 0*C should be reported as 0*C */
+	state.temp_expected = -15 + 273;
+	zassert_equal(EC_SUCCESS,
+		      get_temp_3v0_22k6_47k_4050b(
+				ADC_CHANNEL_3V0_22K6_47K_4050B, &temp),
+		      NULL);
+	zassert_equal(273, temp, "Expected %d*K, got %d*K", 273, temp);
+
+	/* Temperatures above 100*C should be reported as 100*C */
+	state.temp_expected = 115 + 273;
+	zassert_equal(EC_SUCCESS,
+		      get_temp_3v0_22k6_47k_4050b(
+				ADC_CHANNEL_3V0_22K6_47K_4050B, &temp),
+		      NULL);
+	zassert_equal(373, temp, "Expected %d*K, got %d*K", 373, temp);
+}
+
+void test_suite_thermistor(void)
+{
+	const struct device *dev =
+		DEVICE_DT_GET(DT_GPIO_CTLR(GPIO_PG_EC_DSW_PWROK_PATH, gpios));
+
+	zassert_not_null(dev, NULL);
+	/* Before tests make sure that power pin is set. */
+	zassert_ok(gpio_emul_input_set(dev, GPIO_PG_EC_DSW_PWROK_PORT, 1),
+		   NULL);
+
+	ztest_test_suite(thermistor,
+			 ztest_user_unit_test(test_thermistor_power_pin),
+			 ztest_user_unit_test(test_thermistor_adc_read_error),
+			 ztest_user_unit_test(
+					test_thermistor_3v3_13k7_47k_4050b),
+			 ztest_user_unit_test(
+					test_thermistor_3v3_30k9_47k_4050b),
+			 ztest_user_unit_test(
+					test_thermistor_3v3_51k1_47k_4050b),
+			 ztest_user_unit_test(
+					test_thermistor_3v0_22k6_47k_4050b));
+	ztest_run_test_suite(thermistor);
+}