RT9490 : Use ADC thermistor on RT9490

Use thermistor RT9490 for charger temperature.

BUG=b:242267801
TEST=ectool temps all to check it can read thermistor temperature.
BRANCH=None

Signed-off-by: jeffrey <jeffrey_lin@pegatron.corp-partner.google.com>

Change-Id: I91a01adafdc6aca7fcd2afb14c4e6a099826e46e
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3853779
Reviewed-by: Ting Shen <phoenixshen@chromium.org>
Reviewed-by: Jeffrey Lin <jeffrey_lin@pegatron.corp-partner.google.com>
Commit-Queue: Jeffrey Lin <jeffrey_lin@pegatron.corp-partner.google.com>
Tested-by: Jeffrey Lin <jeffrey_lin@pegatron.corp-partner.google.com>

2 files changed, 76 insertions, 0 deletions

diff --git a/driver/charger/rt9490.c b/driver/charger/rt9490.c
index 204949abde..74b2f42ce3 100644
--- a/driver/charger/rt9490.c
+++ b/driver/charger/rt9490.c
@@ -7,6 +7,7 @@
 
 #include "battery.h"
 #include "battery_smart.h"
+#include "builtin/assert.h"
 #include "builtin/endian.h"
 #include "charger.h"
 #include "charge_manager.h"
@@ -20,6 +21,7 @@
 #include "usb_charge.h"
 #include "usb_pd.h"
 #include "util.h"
+#include "temp_sensor/temp_sensor.h"
 
 /* Console output macros */
 #define CPRINTF(format, args...) cprintf(CC_CHARGER, format, ##args)
@@ -734,3 +736,65 @@ 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)
+{
+	uint16_t mv;
+
+	if (idx != 0)
+		return EC_ERROR_PARAM1;
+	rt9490_read16(idx, RT9490_REG_TS_ADC, &mv);
+	*temp_ptr = thermistor_linear(mv, &charger_thermistor_info);
+	*temp_ptr = C_TO_K(*temp_ptr);
+	return EC_SUCCESS;
+}
diff --git a/driver/charger/rt9490.h b/driver/charger/rt9490.h
index 80afb65274..7c718b9028 100644
--- a/driver/charger/rt9490.h
+++ b/driver/charger/rt9490.h
@@ -252,3 +252,15 @@ int rt9490_enable_adc(int chgnum, bool en);
 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 */
+};
+
+struct charger_thermistor_info {
+	uint8_t num_pairs;
+	const struct charger_thermistor_data_pair *data;
+};