1 // SPDX-License-Identifier: GPL-2.0-only
3 * Generic ADC thermal driver
5 * Copyright (C) 2016 NVIDIA CORPORATION. All rights reserved.
7 * Author: Laxman Dewangan <ldewangan@nvidia.com>
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>
16 struct gadc_thermal_info {
18 struct thermal_zone_device *tz_dev;
19 struct iio_channel *channel;
24 static int gadc_thermal_adc_to_temp(struct gadc_thermal_info *gti, int val)
26 int temp, temp_hi, temp_lo, adc_hi, adc_lo;
29 if (!gti->lookup_table)
32 for (i = 0; i < gti->nlookup_table; i++) {
33 if (val >= gti->lookup_table[2 * i + 1])
38 temp = gti->lookup_table[0];
39 } else if (i >= gti->nlookup_table) {
40 temp = gti->lookup_table[2 * (gti->nlookup_table - 1)];
42 adc_hi = gti->lookup_table[2 * i - 1];
43 adc_lo = gti->lookup_table[2 * i + 1];
45 temp_hi = gti->lookup_table[2 * i - 2];
46 temp_lo = gti->lookup_table[2 * i];
48 temp = temp_hi + mult_frac(temp_lo - temp_hi, val - adc_hi,
55 static int gadc_thermal_get_temp(void *data, int *temp)
57 struct gadc_thermal_info *gti = data;
61 ret = iio_read_channel_processed(gti->channel, &val);
63 dev_err(gti->dev, "IIO channel read failed %d\n", ret);
66 *temp = gadc_thermal_adc_to_temp(gti, val);
71 static const struct thermal_zone_of_device_ops gadc_thermal_ops = {
72 .get_temp = gadc_thermal_get_temp,
75 static int gadc_thermal_read_linear_lookup_table(struct device *dev,
76 struct gadc_thermal_info *gti)
78 struct device_node *np = dev->of_node;
82 ntable = of_property_count_elems_of_size(np, "temperature-lookup-table",
85 dev_notice(dev, "no lookup table, assuming DAC channel returns milliCelcius\n");
90 dev_err(dev, "Pair of temperature vs ADC read value missing\n");
94 gti->lookup_table = devm_kcalloc(dev,
95 ntable, sizeof(*gti->lookup_table),
97 if (!gti->lookup_table)
100 ret = of_property_read_u32_array(np, "temperature-lookup-table",
101 (u32 *)gti->lookup_table, ntable);
103 dev_err(dev, "Failed to read temperature lookup table: %d\n",
108 gti->nlookup_table = ntable / 2;
113 static int gadc_thermal_probe(struct platform_device *pdev)
115 struct gadc_thermal_info *gti;
118 if (!pdev->dev.of_node) {
119 dev_err(&pdev->dev, "Only DT based supported\n");
123 gti = devm_kzalloc(&pdev->dev, sizeof(*gti), GFP_KERNEL);
127 ret = gadc_thermal_read_linear_lookup_table(&pdev->dev, gti);
131 gti->dev = &pdev->dev;
132 platform_set_drvdata(pdev, gti);
134 gti->channel = devm_iio_channel_get(&pdev->dev, "sensor-channel");
135 if (IS_ERR(gti->channel)) {
136 ret = PTR_ERR(gti->channel);
137 if (ret != -EPROBE_DEFER)
138 dev_err(&pdev->dev, "IIO channel not found: %d\n", ret);
142 gti->tz_dev = devm_thermal_zone_of_sensor_register(&pdev->dev, 0, gti,
144 if (IS_ERR(gti->tz_dev)) {
145 ret = PTR_ERR(gti->tz_dev);
146 if (ret != -EPROBE_DEFER)
148 "Thermal zone sensor register failed: %d\n",
156 static const struct of_device_id of_adc_thermal_match[] = {
157 { .compatible = "generic-adc-thermal", },
160 MODULE_DEVICE_TABLE(of, of_adc_thermal_match);
162 static struct platform_driver gadc_thermal_driver = {
164 .name = "generic-adc-thermal",
165 .of_match_table = of_adc_thermal_match,
167 .probe = gadc_thermal_probe,
170 module_platform_driver(gadc_thermal_driver);
172 MODULE_AUTHOR("Laxman Dewangan <ldewangan@nvidia.com>");
173 MODULE_DESCRIPTION("Generic ADC thermal driver using IIO framework with DT");
174 MODULE_LICENSE("GPL v2");