GNU Linux-libre 4.9.283-gnu1
[releases.git] / drivers / thermal / thermal-generic-adc.c
1 /*
2  * Generic ADC thermal driver
3  *
4  * Copyright (C) 2016 NVIDIA CORPORATION. All rights reserved.
5  *
6  * Author: Laxman Dewangan <ldewangan@nvidia.com>
7  *
8  * This program is free software; you can redistribute it and/or modify
9  * it under the terms of the GNU General Public License version 2 as
10  * published by the Free Software Foundation.
11  */
12 #include <linux/iio/consumer.h>
13 #include <linux/kernel.h>
14 #include <linux/module.h>
15 #include <linux/platform_device.h>
16 #include <linux/slab.h>
17 #include <linux/thermal.h>
18
19 struct gadc_thermal_info {
20         struct device *dev;
21         struct thermal_zone_device *tz_dev;
22         struct iio_channel *channel;
23         s32 *lookup_table;
24         int nlookup_table;
25 };
26
27 static int gadc_thermal_adc_to_temp(struct gadc_thermal_info *gti, int val)
28 {
29         int temp, temp_hi, temp_lo, adc_hi, adc_lo;
30         int i;
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
55 static 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
71 static const struct thermal_zone_of_device_ops gadc_thermal_ops = {
72         .get_temp = gadc_thermal_get_temp,
73 };
74
75 static 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_err(dev, "Lookup table is not provided\n");
86                 return ntable;
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_kzalloc(dev, sizeof(*gti->lookup_table) *
95                                          ntable, GFP_KERNEL);
96         if (!gti->lookup_table)
97                 return -ENOMEM;
98
99         ret = of_property_read_u32_array(np, "temperature-lookup-table",
100                                          (u32 *)gti->lookup_table, ntable);
101         if (ret < 0) {
102                 dev_err(dev, "Failed to read temperature lookup table: %d\n",
103                         ret);
104                 return ret;
105         }
106
107         gti->nlookup_table = ntable / 2;
108
109         return 0;
110 }
111
112 static int gadc_thermal_probe(struct platform_device *pdev)
113 {
114         struct gadc_thermal_info *gti;
115         int ret;
116
117         if (!pdev->dev.of_node) {
118                 dev_err(&pdev->dev, "Only DT based supported\n");
119                 return -ENODEV;
120         }
121
122         gti = devm_kzalloc(&pdev->dev, sizeof(*gti), GFP_KERNEL);
123         if (!gti)
124                 return -ENOMEM;
125
126         ret = gadc_thermal_read_linear_lookup_table(&pdev->dev, gti);
127         if (ret < 0)
128                 return ret;
129
130         gti->dev = &pdev->dev;
131         platform_set_drvdata(pdev, gti);
132
133         gti->channel = iio_channel_get(&pdev->dev, "sensor-channel");
134         if (IS_ERR(gti->channel)) {
135                 ret = PTR_ERR(gti->channel);
136                 dev_err(&pdev->dev, "IIO channel not found: %d\n", ret);
137                 return ret;
138         }
139
140         gti->tz_dev = thermal_zone_of_sensor_register(&pdev->dev, 0,
141                                                       gti, &gadc_thermal_ops);
142         if (IS_ERR(gti->tz_dev)) {
143                 ret = PTR_ERR(gti->tz_dev);
144                 dev_err(&pdev->dev, "Thermal zone sensor register failed: %d\n",
145                         ret);
146                 goto sensor_fail;
147         }
148
149         return 0;
150
151 sensor_fail:
152         iio_channel_release(gti->channel);
153
154         return ret;
155 }
156
157 static int gadc_thermal_remove(struct platform_device *pdev)
158 {
159         struct gadc_thermal_info *gti = platform_get_drvdata(pdev);
160
161         thermal_zone_of_sensor_unregister(&pdev->dev, gti->tz_dev);
162         iio_channel_release(gti->channel);
163
164         return 0;
165 }
166
167 static const struct of_device_id of_adc_thermal_match[] = {
168         { .compatible = "generic-adc-thermal", },
169         {},
170 };
171 MODULE_DEVICE_TABLE(of, of_adc_thermal_match);
172
173 static struct platform_driver gadc_thermal_driver = {
174         .driver = {
175                 .name = "generic-adc-thermal",
176                 .of_match_table = of_adc_thermal_match,
177         },
178         .probe = gadc_thermal_probe,
179         .remove = gadc_thermal_remove,
180 };
181
182 module_platform_driver(gadc_thermal_driver);
183
184 MODULE_AUTHOR("Laxman Dewangan <ldewangan@nvidia.com>");
185 MODULE_DESCRIPTION("Generic ADC thermal driver using IIO framework with DT");
186 MODULE_LICENSE("GPL v2");