| /* Copyright 2018 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. |
| */ |
| |
| /* Common thermistor code for Chrome EC */ |
| |
| #include "adc.h" |
| #include "common.h" |
| #include "gpio.h" |
| #include "thermistor.h" |
| #include "util.h" |
| |
| int thermistor_linear_interpolate(uint16_t mv, |
| const struct thermistor_info *info) |
| { |
| const struct 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 * info->scaling_factor) |
| return data[0].temp; |
| else if (mv < data[info->num_pairs - 1].mv * info->scaling_factor) |
| 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 * info->scaling_factor; |
| v_low = data[mid + 1].mv * info->scaling_factor; |
| |
| 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; |
| |
| /* |
| * The obvious way of doing this is to figure out how many mV per |
| * degree are in between the two points (mv_per_deg_c), and then how |
| * many of those exist between the input voltage and voltage of |
| * lower temperature : |
| * 1. mv_per_deg_c = (v_high - v_low) / (t_high - t_low) |
| * 2. num_steps = (v_high - mv) / mv_per_deg_c |
| * 3. result = t_low + num_steps |
| * |
| * Combine #1 and #2 to mitigate precision loss due to integer division. |
| */ |
| num_steps = ((v_high - mv) * (t_high - t_low)) / (v_high - v_low); |
| return t_low + num_steps; |
| } |
| |
| #if defined(CONFIG_STEINHART_HART_3V3_51K1_47K_4050B) || \ |
| defined(CONFIG_STEINHART_HART_3V3_13K7_47K_4050B) || \ |
| defined(CONFIG_STEINHART_HART_6V0_51K1_47K_4050B) || \ |
| defined(CONFIG_STEINHART_HART_3V0_22K6_47K_4050B) || \ |
| defined(CONFIG_STEINHART_HART_3V3_30K9_47K_4050B) |
| static int thermistor_get_temperature(int idx_adc, int *temp_ptr, |
| const struct thermistor_info *info) |
| { |
| int mv; |
| |
| #ifdef CONFIG_TEMP_SENSOR_POWER_GPIO |
| /* |
| * If the power rail for the thermistor circuit is not enabled, then |
| * need to ignore any ADC measurments. |
| */ |
| if (!gpio_get_level(CONFIG_TEMP_SENSOR_POWER_GPIO)) |
| return EC_ERROR_NOT_POWERED; |
| #endif /* CONFIG_TEMP_SENSOR_POWER_GPIO */ |
| mv = adc_read_channel(idx_adc); |
| if (mv < 0) |
| return EC_ERROR_UNKNOWN; |
| |
| *temp_ptr = thermistor_linear_interpolate(mv, info); |
| *temp_ptr = C_TO_K(*temp_ptr); |
| return EC_SUCCESS; |
| } |
| #endif |
| |
| #ifdef CONFIG_STEINHART_HART_3V3_51K1_47K_4050B |
| /* |
| * Data derived from Steinhart-Hart equation in a resistor divider circuit with |
| * Vdd=3300mV, R = 51.1Kohm, and thermistor (B = 4050, T0 = 298.15 K, nominal |
| * resistance (R0) = 47Kohm). |
| */ |
| #define THERMISTOR_SCALING_FACTOR_51_47 11 |
| static const struct thermistor_data_pair thermistor_data_51_47[] = { |
| { 2512 / THERMISTOR_SCALING_FACTOR_51_47, 0 }, |
| { 2158 / THERMISTOR_SCALING_FACTOR_51_47, 10 }, |
| { 1772 / THERMISTOR_SCALING_FACTOR_51_47, 20 }, |
| { 1398 / THERMISTOR_SCALING_FACTOR_51_47, 30 }, |
| { 1070 / THERMISTOR_SCALING_FACTOR_51_47, 40 }, |
| { 803 / THERMISTOR_SCALING_FACTOR_51_47, 50 }, |
| { 597 / THERMISTOR_SCALING_FACTOR_51_47, 60 }, |
| { 443 / THERMISTOR_SCALING_FACTOR_51_47, 70 }, |
| { 329 / THERMISTOR_SCALING_FACTOR_51_47, 80 }, |
| { 285 / THERMISTOR_SCALING_FACTOR_51_47, 85 }, |
| { 247 / THERMISTOR_SCALING_FACTOR_51_47, 90 }, |
| { 214 / THERMISTOR_SCALING_FACTOR_51_47, 95 }, |
| { 187 / THERMISTOR_SCALING_FACTOR_51_47, 100 }, |
| }; |
| |
| static const struct thermistor_info thermistor_info_51_47 = { |
| .scaling_factor = THERMISTOR_SCALING_FACTOR_51_47, |
| .num_pairs = ARRAY_SIZE(thermistor_data_51_47), |
| .data = thermistor_data_51_47, |
| }; |
| |
| int get_temp_3v3_51k1_47k_4050b(int idx_adc, int *temp_ptr) |
| { |
| return thermistor_get_temperature(idx_adc, temp_ptr, |
| &thermistor_info_51_47); |
| } |
| #endif /* CONFIG_STEINHART_HART_3V3_51K1_47K_4050B */ |
| |
| #ifdef CONFIG_STEINHART_HART_3V3_13K7_47K_4050B |
| /* |
| * Data derived from Steinhart-Hart equation in a resistor divider circuit with |
| * Vdd=3300mV, R = 13.7Kohm, and thermistor (B = 4050, T0 = 298.15 K, nominal |
| * resistance (R0) = 47Kohm). |
| */ |
| #define THERMISTOR_SCALING_FACTOR_13_47 13 |
| static const struct thermistor_data_pair thermistor_data_13_47[] = { |
| { 3044 / THERMISTOR_SCALING_FACTOR_13_47, 0 }, |
| { 2890 / THERMISTOR_SCALING_FACTOR_13_47, 10 }, |
| { 2680 / THERMISTOR_SCALING_FACTOR_13_47, 20 }, |
| { 2418 / THERMISTOR_SCALING_FACTOR_13_47, 30 }, |
| { 2117 / THERMISTOR_SCALING_FACTOR_13_47, 40 }, |
| { 1800 / THERMISTOR_SCALING_FACTOR_13_47, 50 }, |
| { 1490 / THERMISTOR_SCALING_FACTOR_13_47, 60 }, |
| { 1208 / THERMISTOR_SCALING_FACTOR_13_47, 70 }, |
| { 966 / THERMISTOR_SCALING_FACTOR_13_47, 80 }, |
| { 860 / THERMISTOR_SCALING_FACTOR_13_47, 85 }, |
| { 766 / THERMISTOR_SCALING_FACTOR_13_47, 90 }, |
| { 679 / THERMISTOR_SCALING_FACTOR_13_47, 95 }, |
| { 603 / THERMISTOR_SCALING_FACTOR_13_47, 100 }, |
| }; |
| |
| static const struct thermistor_info thermistor_info_13_47 = { |
| .scaling_factor = THERMISTOR_SCALING_FACTOR_13_47, |
| .num_pairs = ARRAY_SIZE(thermistor_data_13_47), |
| .data = thermistor_data_13_47, |
| }; |
| |
| int get_temp_3v3_13k7_47k_4050b(int idx_adc, int *temp_ptr) |
| { |
| return thermistor_get_temperature(idx_adc, temp_ptr, |
| &thermistor_info_13_47); |
| } |
| #endif /* CONFIG_STEINHART_HART_3V3_13K7_47K_4050B */ |
| |
| #ifdef CONFIG_STEINHART_HART_6V0_51K1_47K_4050B |
| /* |
| * Data derived from Steinhart-Hart equation in a resistor divider circuit with |
| * Vdd=6000mV, R = 51.1Kohm, and thermistor (B = 4050, T0 = 298.15 K, nominal |
| * resistance (R0) = 47Kohm). |
| */ |
| #define THERMISTOR_SCALING_FACTOR_6V0_51_47 18 |
| static const struct thermistor_data_pair thermistor_data_6v0_51_47[] = { |
| { 4517 / THERMISTOR_SCALING_FACTOR_6V0_51_47, 0 }, |
| { 3895 / THERMISTOR_SCALING_FACTOR_6V0_51_47, 10 }, |
| { 3214 / THERMISTOR_SCALING_FACTOR_6V0_51_47, 20 }, |
| { 2546 / THERMISTOR_SCALING_FACTOR_6V0_51_47, 30 }, |
| { 1950 / THERMISTOR_SCALING_FACTOR_6V0_51_47, 40 }, |
| { 1459 / THERMISTOR_SCALING_FACTOR_6V0_51_47, 50 }, |
| { 1079 / THERMISTOR_SCALING_FACTOR_6V0_51_47, 60 }, |
| { 794 / THERMISTOR_SCALING_FACTOR_6V0_51_47, 70 }, |
| { 584 / THERMISTOR_SCALING_FACTOR_6V0_51_47, 80 }, |
| { 502 / THERMISTOR_SCALING_FACTOR_6V0_51_47, 85 }, |
| { 432 / THERMISTOR_SCALING_FACTOR_6V0_51_47, 90 }, |
| { 372 / THERMISTOR_SCALING_FACTOR_6V0_51_47, 95 }, |
| { 322 / THERMISTOR_SCALING_FACTOR_6V0_51_47, 100 }, |
| }; |
| |
| static const struct thermistor_info thermistor_info_6v0_51_47 = { |
| .scaling_factor = THERMISTOR_SCALING_FACTOR_6V0_51_47, |
| .num_pairs = ARRAY_SIZE(thermistor_data_6v0_51_47), |
| .data = thermistor_data_6v0_51_47, |
| }; |
| |
| int get_temp_6v0_51k1_47k_4050b(int idx_adc, int *temp_ptr) |
| { |
| return thermistor_get_temperature(idx_adc, temp_ptr, |
| &thermistor_info_6v0_51_47); |
| } |
| #endif /* CONFIG_STEINHART_HART_6V0_51K1_47K_4050B */ |
| |
| #ifdef CONFIG_STEINHART_HART_3V0_22K6_47K_4050B |
| /* |
| * Data derived from Steinhart-Hart equation in a resistor divider circuit with |
| * Vdd=3000mV, R = 22.6Kohm, and thermistor (B = 4050, T0 = 298.15 K, nominal |
| * resistance (R0) = 47Kohm). |
| */ |
| #define THERMISTOR_SCALING_FACTOR_22_47 11 |
| static const struct thermistor_data_pair thermistor_data_22_47[] = { |
| { 2625 / THERMISTOR_SCALING_FACTOR_22_47, 0 }, |
| { 2425 / THERMISTOR_SCALING_FACTOR_22_47, 10 }, |
| { 2170 / THERMISTOR_SCALING_FACTOR_22_47, 20 }, |
| { 1875 / THERMISTOR_SCALING_FACTOR_22_47, 30 }, |
| { 1563 / THERMISTOR_SCALING_FACTOR_22_47, 40 }, |
| { 1263 / THERMISTOR_SCALING_FACTOR_22_47, 50 }, |
| { 995 / THERMISTOR_SCALING_FACTOR_22_47, 60 }, |
| { 770 / THERMISTOR_SCALING_FACTOR_22_47, 70 }, |
| { 589 / THERMISTOR_SCALING_FACTOR_22_47, 80 }, |
| { 514 / THERMISTOR_SCALING_FACTOR_22_47, 85 }, |
| { 448 / THERMISTOR_SCALING_FACTOR_22_47, 90 }, |
| { 391 / THERMISTOR_SCALING_FACTOR_22_47, 95 }, |
| { 341 / THERMISTOR_SCALING_FACTOR_22_47, 100 }, |
| }; |
| |
| static const struct thermistor_info thermistor_info_22_47 = { |
| .scaling_factor = THERMISTOR_SCALING_FACTOR_22_47, |
| .num_pairs = ARRAY_SIZE(thermistor_data_22_47), |
| .data = thermistor_data_22_47, |
| }; |
| |
| int get_temp_3v0_22k6_47k_4050b(int idx_adc, int *temp_ptr) |
| { |
| return thermistor_get_temperature(idx_adc, temp_ptr, |
| &thermistor_info_22_47); |
| } |
| #endif /* CONFIG_STEINHART_HART_3V0_22K6_47K_4050B */ |
| |
| #ifdef CONFIG_STEINHART_HART_3V3_30K9_47K_4050B |
| /* |
| * Data derived from Steinhart-Hart equation in a resistor divider circuit with |
| * Vdd=3000mV, R = 30.9Kohm, and thermistor (B = 4050, T0 = 298.15 K, nominal |
| * resistance (R0) = 47Kohm). |
| */ |
| #define THERMISTOR_SCALING_FACTOR_31_47 11 |
| static const struct thermistor_data_pair thermistor_data_31_47[] = { |
| { 2753 / THERMISTOR_SCALING_FACTOR_31_47, 0 }, |
| { 2487 / THERMISTOR_SCALING_FACTOR_31_47, 10 }, |
| { 2165 / THERMISTOR_SCALING_FACTOR_31_47, 20 }, |
| { 1813 / THERMISTOR_SCALING_FACTOR_31_47, 30 }, |
| { 1145 / THERMISTOR_SCALING_FACTOR_31_47, 50 }, |
| { 878 / THERMISTOR_SCALING_FACTOR_31_47, 60 }, |
| { 665 / THERMISTOR_SCALING_FACTOR_31_47, 70 }, |
| { 500 / THERMISTOR_SCALING_FACTOR_31_47, 80 }, |
| { 375 / THERMISTOR_SCALING_FACTOR_31_47, 90 }, |
| { 282 / THERMISTOR_SCALING_FACTOR_31_47, 100 }, |
| }; |
| |
| static const struct thermistor_info thermistor_info_31_47 = { |
| .scaling_factor = THERMISTOR_SCALING_FACTOR_31_47, |
| .num_pairs = ARRAY_SIZE(thermistor_data_31_47), |
| .data = thermistor_data_31_47, |
| }; |
| |
| int get_temp_3v3_30k9_47k_4050b(int idx_adc, int *temp_ptr) |
| { |
| return thermistor_get_temperature(idx_adc, temp_ptr, |
| &thermistor_info_31_47); |
| } |
| #endif /* CONFIG_STEINHART_HART_3V3_30K9_47K_4050B */ |
