temp-sensor-rt9490: migrate to common thermistor code

Reuse existing linear interpolation algorithm and dts structure for
rt9490 temperature calculation.

BUG=none
TEST=`temps` in ec console looks reasonable:
      ec:~$ temps
      ambient               324 K (= 51 C)
      charger               322 K (= 49 C)
BRANCH=none

Signed-off-by: Ting Shen <phoenixshen@google.com>
Change-Id: If69d9332d81a5b23b851c76c2e0539d62cbdfe09
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3865584
Tested-by: Ting Shen <phoenixshen@chromium.org>
Reviewed-by: Eric Yilun Lin <yllin@google.com>
Commit-Queue: Ting Shen <phoenixshen@chromium.org>

7 files changed, 170 insertions, 75 deletions

diff --git a/driver/charger/rt9490.c b/driver/charger/rt9490.c
index c950150128..e663b8ee79 100644
--- a/driver/charger/rt9490.c
+++ b/driver/charger/rt9490.c
@@ -22,6 +22,7 @@
 #include "usb_pd.h"
 #include "util.h"
 #include "temp_sensor/temp_sensor.h"
+#include "temp_sensor/thermistor.h"
 
 /* Console output macros */
 #define CPRINTF(format, args...) cprintf(CC_CHARGER, format, ##args)
@@ -737,64 +738,20 @@ struct bc12_config bc12_ports[CHARGE_PORT_COUNT] = {
 };
 #endif /* CONFIG_BC12_SINGLE_DRIVER */
 
-__overridable struct charger_thermistor_data_pair charger_thermistor_data[] = {
-	{ 731, 0 },   { 708, 5 },  { 682, 10 }, { 653, 15 }, { 622, 20 },
-	{ 589, 25 },  { 554, 30 }, { 519, 35 }, { 483, 40 }, { 446, 45 },
-	{ 411, 50 },  { 376, 55 }, { 343, 60 }, { 312, 65 }, { 284, 70 },
-	{ 257, 75 },  { 232, 80 }, { 209, 85 }, { 188, 90 }, { 169, 95 },
-	{ 152, 100 },
-};
-
-__overridable struct charger_thermistor_info charger_thermistor_info = {
-	.num_pairs = ARRAY_SIZE(charger_thermistor_data),
-	.data = charger_thermistor_data,
-};
-
-int thermistor_linear(uint16_t mv, const struct charger_thermistor_info *info)
-{
-	const struct charger_thermistor_data_pair *data = info->data;
-	int v_high = 0, v_low = 0, t_low, t_high, num_steps;
-	int head, tail, mid = 0;
-	/* We need at least two points to form a line. */
-	ASSERT(info->num_pairs >= 2);
-
-	/*
-	 * If input value is out of bounds return the lowest or highest
-	 * value in the data sets provided.
-	 */
-	if (mv > data[0].mv)
-		return data[0].temp;
-	else if (mv < data[info->num_pairs - 1].mv)
-		return data[info->num_pairs - 1].temp;
-
-	head = 0;
-	tail = info->num_pairs - 1;
-	while (head != tail) {
-		mid = (head + tail) / 2;
-		v_high = data[mid].mv;
-		v_low = data[mid + 1].mv;
-		if ((mv <= v_high) && (mv >= v_low))
-			break;
-		else if (mv > v_high)
-			tail = mid;
-		else if (mv < v_low)
-			head = mid + 1;
-	}
-
-	t_low = data[mid].temp;
-	t_high = data[mid + 1].temp;
-	num_steps = ((v_high - mv) * (t_high - t_low)) / (v_high - v_low);
-	return t_low + num_steps;
-}
-
-int rt9490_get_thermistor_val(int idx, int *temp_ptr)
+int rt9490_get_thermistor_val(const struct temp_sensor_t *sensor, int *temp_ptr)
 {
 	uint16_t mv;
+	int idx = sensor->idx;
+#if IS_ENABLED(CONFIG_ZEPHYR) && IS_ENABLED(CONFIG_TEMP_SENSOR)
+	const struct thermistor_info *info = sensor->zephyr_info->thermistor;
+#else
+	const struct thermistor_info *info = &rt9490_thermistor_info;
+#endif
 
 	if (idx != 0)
 		return EC_ERROR_PARAM1;
-	rt9490_read16(idx, RT9490_REG_TS_ADC, &mv);
-	*temp_ptr = thermistor_linear(mv, &charger_thermistor_info);
+	RETURN_ERROR(rt9490_read16(idx, RT9490_REG_TS_ADC, &mv));
+	*temp_ptr = thermistor_linear_interpolate(mv, info);
 	*temp_ptr = C_TO_K(*temp_ptr);
 	return EC_SUCCESS;
 }
diff --git a/driver/charger/rt9490.h b/driver/charger/rt9490.h
index 7c718b9028..1a7abc51d3 100644
--- a/driver/charger/rt9490.h
+++ b/driver/charger/rt9490.h
@@ -6,6 +6,8 @@
  */
 #include <stdbool.h>
 
+#include "temp_sensor.h"
+
 #ifndef __CROS_EC_RT9490_H
 #define __CROS_EC_RT9490_H
 
@@ -253,14 +255,11 @@ int rt9490_enable_pwm_1mhz(int chgnum, bool en);
 
 #endif /* __CROS_EC_RT9490_H */
 
-int rt9490_get_thermistor_val(int idx, int *temp_ptr);
-
-struct charger_thermistor_data_pair {
-	uint16_t mv; /* Scaled voltage level at ADC (in mV) */
-	uint8_t temp; /* Temperature in Celsius */
-};
+/*
+ * Required for TS_ADC temperature calculation.
+ * Non-zephyr devices that using TS_ADC must define this in board layer.
+ */
+extern const struct thermistor_info rt9490_thermistor_info;
 
-struct charger_thermistor_info {
-	uint8_t num_pairs;
-	const struct charger_thermistor_data_pair *data;
-};
+int rt9490_get_thermistor_val(const struct temp_sensor_t *sensor,
+			      int *temp_ptr);
diff --git a/zephyr/dts/bindings/temp/cros-ec,temp-sensor-rt9490.yaml b/zephyr/dts/bindings/temp/cros-ec,temp-sensor-rt9490.yaml
index ae9da7fb62..260dcbf0c7 100644
--- a/zephyr/dts/bindings/temp/cros-ec,temp-sensor-rt9490.yaml
+++ b/zephyr/dts/bindings/temp/cros-ec,temp-sensor-rt9490.yaml
@@ -14,3 +14,7 @@ properties:
       required: true
       type: phandle
       description: phandle to the named i2c port
+
+    thermistor:
+      type: phandle
+      description: Underlying thermistor device
diff --git a/zephyr/projects/corsola/BUILD.py b/zephyr/projects/corsola/BUILD.py
index ce16e4ff86..94959e4d9f 100644
--- a/zephyr/projects/corsola/BUILD.py
+++ b/zephyr/projects/corsola/BUILD.py
@@ -110,6 +110,7 @@ register_corsola_project(
         here / "led_tentacruel.dts",
         here / "motionsense_tentacruel.dts",
         here / "usbc_tentacruel.dts",
+        here / "thermistor_tentacruel.dts",
     ],
     extra_kconfig_files=[
         here / "prj_it81202_base.conf",
diff --git a/zephyr/projects/corsola/adc_tentacruel.dts b/zephyr/projects/corsola/adc_tentacruel.dts
index 8a4a22f6c0..86acd14399 100644
--- a/zephyr/projects/corsola/adc_tentacruel.dts
+++ b/zephyr/projects/corsola/adc_tentacruel.dts
@@ -55,6 +55,7 @@
 		charger {
 			compatible = "cros-ec,temp-sensor-rt9490",
 				     "cros-ec,temp-sensor";
+			thermistor = <&thermistor_rt9490>;
 			enum-name = "TEMP_SENSOR_CHARGER";
 			port = <&i2c_charger>;
 		};
diff --git a/zephyr/projects/corsola/thermistor_tentacruel.dts b/zephyr/projects/corsola/thermistor_tentacruel.dts
new file mode 100644
index 0000000000..9ac1b5cf58
--- /dev/null
+++ b/zephyr/projects/corsola/thermistor_tentacruel.dts
@@ -0,0 +1,140 @@
+/* Copyright 2022 The ChromiumOS Authors.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+/ {
+	thermistor_rt9490: thermistor-rt9490 {
+		status = "okay";
+		compatible = "cros-ec,thermistor";
+		scaling-factor = <3>;
+		num-pairs = <21>;
+		steinhart-reference-mv = <4900>;
+		steinhart-reference-res = <10000>;
+
+		sample-datum-0 {
+			milivolt = <(731 / 3)>;
+			temp = <0>;
+			sample-index = <0>;
+		};
+
+		sample-datum-1 {
+			milivolt = <(708 / 3)>;
+			temp = <5>;
+			sample-index = <1>;
+		};
+
+		sample-datum-2 {
+			milivolt = <(682 / 3)>;
+			temp = <10>;
+			sample-index = <2>;
+		};
+
+		sample-datum-3 {
+			milivolt = <(653 / 3)>;
+			temp = <15>;
+			sample-index = <3>;
+		};
+
+		sample-datum-4 {
+			milivolt = <(622 / 3)>;
+			temp = <20>;
+			sample-index = <4>;
+		};
+
+		sample-datum-5 {
+			milivolt = <(589 / 3)>;
+			temp = <25>;
+			sample-index = <5>;
+		};
+
+		sample-datum-6 {
+			milivolt = <(554 / 3)>;
+			temp = <30>;
+			sample-index = <6>;
+		};
+
+		sample-datum-7 {
+			milivolt = <(519 / 3)>;
+			temp = <35>;
+			sample-index = <7>;
+		};
+
+		sample-datum-8 {
+			milivolt = <(483 / 3)>;
+			temp = <40>;
+			sample-index = <8>;
+		};
+
+		sample-datum-9 {
+			milivolt = <(446 / 3)>;
+			temp = <45>;
+			sample-index = <9>;
+		};
+
+		sample-datum-10 {
+			milivolt = <(411 / 3)>;
+			temp = <50>;
+			sample-index = <10>;
+		};
+		sample-datum-11 {
+			milivolt = <(376 / 3)>;
+			temp = <55>;
+			sample-index = <11>;
+		};
+
+		sample-datum-12 {
+			milivolt = <(343 / 3)>;
+			temp = <60>;
+			sample-index = <12>;
+		};
+
+		sample-datum-13 {
+			milivolt = <(312 / 3)>;
+			temp = <65>;
+			sample-index = <13>;
+		};
+
+		sample-datum-14 {
+			milivolt = <(284 / 3)>;
+			temp = <70>;
+			sample-index = <14>;
+		};
+
+		sample-datum-15 {
+			milivolt = <(257 / 3)>;
+			temp = <75>;
+			sample-index = <15>;
+		};
+
+		sample-datum-16 {
+			milivolt = <(232 / 3)>;
+			temp = <80>;
+			sample-index = <16>;
+		};
+
+		sample-datum-17 {
+			milivolt = <(209 / 3)>;
+			temp = <85>;
+			sample-index = <17>;
+		};
+
+		sample-datum-18 {
+			milivolt = <(188 / 3)>;
+			temp = <90>;
+			sample-index = <18>;
+		};
+
+		sample-datum-19 {
+			milivolt = <(169 / 3)>;
+			temp = <95>;
+			sample-index = <19>;
+		};
+
+		sample-datum-20 {
+			milivolt = <(152 / 3)>;
+			temp = <100>;
+			sample-index = <20>;
+		};
+	};
+};
diff --git a/zephyr/shim/src/temp_sensors.c b/zephyr/shim/src/temp_sensors.c
index 46a4c1fd8f..28d012047c 100644
--- a/zephyr/shim/src/temp_sensors.c
+++ b/zephyr/shim/src/temp_sensors.c
@@ -160,23 +160,16 @@ const struct tmp112_sensor_t tmp112_sensors[TMP112_COUNT] = {
 	DT_FOREACH_STATUS_OKAY(cros_ec_temp_sensor_tmp112, DEFINE_TMP112_DATA)
 };
 
-#if DT_HAS_COMPAT_STATUS_OKAY(cros_ec_temp_sensor_rt9490)
-static int rt9490_get_temp(const struct temp_sensor_t *sensor, int *temp_ptr)
-{
-	return rt9490_get_thermistor_val(sensor->idx, temp_ptr);
-}
-
 /* There can be only one thermistor on RT9490 with current driver */
 #if DT_NUM_INST_STATUS_OKAY(cros_ec_temp_sensor_rt9490) > 1
 #error "Unsupported number of thermistor on RT9490"
 #endif
 
-#endif /* cros_ec_temp_sensor_rt9490 */
-
-#define GET_ZEPHYR_TEMP_SENSOR_RT9490(node_id) \
-	(&(struct zephyr_temp_sensor){         \
-		.read = &rt9490_get_temp,      \
-		.thermistor = NULL,            \
+#define GET_ZEPHYR_TEMP_SENSOR_RT9490(node_id)                                \
+	(&(struct zephyr_temp_sensor){                                        \
+		.read = &rt9490_get_thermistor_val,                           \
+		.thermistor =                                                 \
+			GET_THERMISTOR_INFO(DT_PHANDLE(node_id, thermistor)), \
 	})
 
 #define TEMP_RT9490(node_id)                                           \