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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * Generic ADC thermal driver4 *5 * Copyright (C) 2016 NVIDIA CORPORATION. All rights reserved.6 *7 * Author: Laxman Dewangan <ldewangan@nvidia.com>8 */9#include <linux/iio/consumer.h>10#include <linux/kernel.h>11#include <linux/module.h>12#include <linux/platform_device.h>13#include <linux/slab.h>14#include <linux/thermal.h>15 16#include "thermal_hwmon.h"17 18struct gadc_thermal_info {19 struct device *dev;20 struct thermal_zone_device *tz_dev;21 struct iio_channel *channel;22 s32 *lookup_table;23 int nlookup_table;24};25 26static int gadc_thermal_adc_to_temp(struct gadc_thermal_info *gti, int val)27{28 int temp, temp_hi, temp_lo, adc_hi, adc_lo;29 int i;30 31 if (!gti->lookup_table)32 return val;33 34 for (i = 0; i < gti->nlookup_table; i++) {35 if (val >= gti->lookup_table[2 * i + 1])36 break;37 }38 39 if (i == 0) {40 temp = gti->lookup_table[0];41 } else if (i >= gti->nlookup_table) {42 temp = gti->lookup_table[2 * (gti->nlookup_table - 1)];43 } else {44 adc_hi = gti->lookup_table[2 * i - 1];45 adc_lo = gti->lookup_table[2 * i + 1];46 47 temp_hi = gti->lookup_table[2 * i - 2];48 temp_lo = gti->lookup_table[2 * i];49 50 temp = temp_hi + mult_frac(temp_lo - temp_hi, val - adc_hi,51 adc_lo - adc_hi);52 }53 54 return temp;55}56 57static int gadc_thermal_get_temp(struct thermal_zone_device *tz, int *temp)58{59 struct gadc_thermal_info *gti = thermal_zone_device_priv(tz);60 int val;61 int ret;62 63 ret = iio_read_channel_processed(gti->channel, &val);64 if (ret < 0)65 return ret;66 67 *temp = gadc_thermal_adc_to_temp(gti, val);68 69 return 0;70}71 72static const struct thermal_zone_device_ops gadc_thermal_ops = {73 .get_temp = gadc_thermal_get_temp,74};75 76static int gadc_thermal_read_linear_lookup_table(struct device *dev,77 struct gadc_thermal_info *gti)78{79 struct device_node *np = dev->of_node;80 enum iio_chan_type chan_type;81 int ntable;82 int ret;83 84 ntable = of_property_count_elems_of_size(np, "temperature-lookup-table",85 sizeof(u32));86 if (ntable <= 0) {87 ret = iio_get_channel_type(gti->channel, &chan_type);88 if (ret || chan_type != IIO_TEMP)89 dev_notice(dev,90 "no lookup table, assuming DAC channel returns milliCelcius\n");91 return 0;92 }93 94 if (ntable % 2) {95 dev_err(dev, "Pair of temperature vs ADC read value missing\n");96 return -EINVAL;97 }98 99 gti->lookup_table = devm_kcalloc(dev,100 ntable, sizeof(*gti->lookup_table),101 GFP_KERNEL);102 if (!gti->lookup_table)103 return -ENOMEM;104 105 ret = of_property_read_u32_array(np, "temperature-lookup-table",106 (u32 *)gti->lookup_table, ntable);107 if (ret < 0) {108 dev_err(dev, "Failed to read temperature lookup table: %d\n",109 ret);110 return ret;111 }112 113 gti->nlookup_table = ntable / 2;114 115 return 0;116}117 118static int gadc_thermal_probe(struct platform_device *pdev)119{120 struct device *dev = &pdev->dev;121 struct gadc_thermal_info *gti;122 int ret;123 124 if (!dev->of_node) {125 dev_err(dev, "Only DT based supported\n");126 return -ENODEV;127 }128 129 gti = devm_kzalloc(dev, sizeof(*gti), GFP_KERNEL);130 if (!gti)131 return -ENOMEM;132 133 gti->channel = devm_iio_channel_get(dev, "sensor-channel");134 if (IS_ERR(gti->channel))135 return dev_err_probe(dev, PTR_ERR(gti->channel), "IIO channel not found\n");136 137 ret = gadc_thermal_read_linear_lookup_table(dev, gti);138 if (ret < 0)139 return ret;140 141 gti->dev = dev;142 143 gti->tz_dev = devm_thermal_of_zone_register(dev, 0, gti,144 &gadc_thermal_ops);145 if (IS_ERR(gti->tz_dev)) {146 ret = PTR_ERR(gti->tz_dev);147 if (ret != -EPROBE_DEFER)148 dev_err(dev,149 "Thermal zone sensor register failed: %d\n",150 ret);151 return ret;152 }153 154 devm_thermal_add_hwmon_sysfs(dev, gti->tz_dev);155 156 return 0;157}158 159static const struct of_device_id of_adc_thermal_match[] = {160 { .compatible = "generic-adc-thermal", },161 {},162};163MODULE_DEVICE_TABLE(of, of_adc_thermal_match);164 165static struct platform_driver gadc_thermal_driver = {166 .driver = {167 .name = "generic-adc-thermal",168 .of_match_table = of_adc_thermal_match,169 },170 .probe = gadc_thermal_probe,171};172 173module_platform_driver(gadc_thermal_driver);174 175MODULE_AUTHOR("Laxman Dewangan <ldewangan@nvidia.com>");176MODULE_DESCRIPTION("Generic ADC thermal driver using IIO framework with DT");177MODULE_LICENSE("GPL v2");178