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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 | { | |
919fc06b | 29 | int temp, temp_hi, temp_lo, adc_hi, adc_lo; |
b3aef78f LD |
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]; | |
919fc06b | 39 | } else if (i >= gti->nlookup_table) { |
b3aef78f LD |
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]; | |
919fc06b BA |
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); | |
b3aef78f LD |
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"); |