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