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b3aef78f LD |
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, 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 - 1)) { | |
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 | temp = gti->lookup_table[2 * i]; | |
45 | temp -= ((val - adc_lo) * 1000) / (adc_hi - adc_lo); | |
46 | } | |
47 | ||
48 | return temp; | |
49 | } | |
50 | ||
51 | static int gadc_thermal_get_temp(void *data, int *temp) | |
52 | { | |
53 | struct gadc_thermal_info *gti = data; | |
54 | int val; | |
55 | int ret; | |
56 | ||
57 | ret = iio_read_channel_processed(gti->channel, &val); | |
58 | if (ret < 0) { | |
59 | dev_err(gti->dev, "IIO channel read failed %d\n", ret); | |
60 | return ret; | |
61 | } | |
62 | *temp = gadc_thermal_adc_to_temp(gti, val); | |
63 | ||
64 | return 0; | |
65 | } | |
66 | ||
67 | static const struct thermal_zone_of_device_ops gadc_thermal_ops = { | |
68 | .get_temp = gadc_thermal_get_temp, | |
69 | }; | |
70 | ||
71 | static int gadc_thermal_read_linear_lookup_table(struct device *dev, | |
72 | struct gadc_thermal_info *gti) | |
73 | { | |
74 | struct device_node *np = dev->of_node; | |
75 | int ntable; | |
76 | int ret; | |
77 | ||
78 | ntable = of_property_count_elems_of_size(np, "temperature-lookup-table", | |
79 | sizeof(u32)); | |
80 | if (ntable < 0) { | |
81 | dev_err(dev, "Lookup table is not provided\n"); | |
82 | return ntable; | |
83 | } | |
84 | ||
85 | if (ntable % 2) { | |
86 | dev_err(dev, "Pair of temperature vs ADC read value missing\n"); | |
87 | return -EINVAL; | |
88 | } | |
89 | ||
90 | gti->lookup_table = devm_kzalloc(dev, sizeof(*gti->lookup_table) * | |
91 | ntable, GFP_KERNEL); | |
92 | if (!gti->lookup_table) | |
93 | return -ENOMEM; | |
94 | ||
95 | ret = of_property_read_u32_array(np, "temperature-lookup-table", | |
96 | (u32 *)gti->lookup_table, ntable); | |
97 | if (ret < 0) { | |
98 | dev_err(dev, "Failed to read temperature lookup table: %d\n", | |
99 | ret); | |
100 | return ret; | |
101 | } | |
102 | ||
103 | gti->nlookup_table = ntable / 2; | |
104 | ||
105 | return 0; | |
106 | } | |
107 | ||
108 | static int gadc_thermal_probe(struct platform_device *pdev) | |
109 | { | |
110 | struct gadc_thermal_info *gti; | |
111 | int ret; | |
112 | ||
113 | if (!pdev->dev.of_node) { | |
114 | dev_err(&pdev->dev, "Only DT based supported\n"); | |
115 | return -ENODEV; | |
116 | } | |
117 | ||
118 | gti = devm_kzalloc(&pdev->dev, sizeof(*gti), GFP_KERNEL); | |
119 | if (!gti) | |
120 | return -ENOMEM; | |
121 | ||
122 | ret = gadc_thermal_read_linear_lookup_table(&pdev->dev, gti); | |
123 | if (ret < 0) | |
124 | return ret; | |
125 | ||
126 | gti->dev = &pdev->dev; | |
127 | platform_set_drvdata(pdev, gti); | |
128 | ||
129 | gti->channel = iio_channel_get(&pdev->dev, "sensor-channel"); | |
130 | if (IS_ERR(gti->channel)) { | |
131 | ret = PTR_ERR(gti->channel); | |
132 | dev_err(&pdev->dev, "IIO channel not found: %d\n", ret); | |
133 | return ret; | |
134 | } | |
135 | ||
136 | gti->tz_dev = thermal_zone_of_sensor_register(&pdev->dev, 0, | |
137 | gti, &gadc_thermal_ops); | |
138 | if (IS_ERR(gti->tz_dev)) { | |
139 | ret = PTR_ERR(gti->tz_dev); | |
140 | dev_err(&pdev->dev, "Thermal zone sensor register failed: %d\n", | |
141 | ret); | |
142 | goto sensor_fail; | |
143 | } | |
144 | ||
145 | return 0; | |
146 | ||
147 | sensor_fail: | |
148 | iio_channel_release(gti->channel); | |
149 | ||
150 | return ret; | |
151 | } | |
152 | ||
153 | static int gadc_thermal_remove(struct platform_device *pdev) | |
154 | { | |
155 | struct gadc_thermal_info *gti = platform_get_drvdata(pdev); | |
156 | ||
157 | thermal_zone_of_sensor_unregister(&pdev->dev, gti->tz_dev); | |
158 | iio_channel_release(gti->channel); | |
159 | ||
160 | return 0; | |
161 | } | |
162 | ||
163 | static const struct of_device_id of_adc_thermal_match[] = { | |
164 | { .compatible = "generic-adc-thermal", }, | |
165 | {}, | |
166 | }; | |
167 | MODULE_DEVICE_TABLE(of, of_adc_thermal_match); | |
168 | ||
169 | static struct platform_driver gadc_thermal_driver = { | |
170 | .driver = { | |
171 | .name = "generic-adc-thermal", | |
172 | .of_match_table = of_adc_thermal_match, | |
173 | }, | |
174 | .probe = gadc_thermal_probe, | |
175 | .remove = gadc_thermal_remove, | |
176 | }; | |
177 | ||
178 | module_platform_driver(gadc_thermal_driver); | |
179 | ||
180 | MODULE_AUTHOR("Laxman Dewangan <ldewangan@nvidia.com>"); | |
181 | MODULE_DESCRIPTION("Generic ADC thermal driver using IIO framework with DT"); | |
182 | MODULE_LICENSE("GPL v2"); |