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d2912cb1 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
b3aef78f LD |
2 | /* |
3 | * Generic ADC thermal driver | |
4 | * | |
5 | * Copyright (C) 2016 NVIDIA CORPORATION. All rights reserved. | |
6 | * | |
7 | * Author: Laxman Dewangan <ldewangan@nvidia.com> | |
b3aef78f LD |
8 | */ |
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 | ||
16 | struct 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 | ||
24 | static int gadc_thermal_adc_to_temp(struct gadc_thermal_info *gti, int val) | |
25 | { | |
9d216211 | 26 | int temp, temp_hi, temp_lo, adc_hi, adc_lo; |
b3aef78f LD |
27 | int i; |
28 | ||
d36e2fa0 JFD |
29 | if (!gti->lookup_table) |
30 | return val; | |
31 | ||
b3aef78f LD |
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]; | |
9d216211 | 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]; | |
9d216211 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; | |
07d243a6 | 79 | enum iio_chan_type chan_type; |
b3aef78f LD |
80 | int ntable; |
81 | int ret; | |
82 | ||
83 | ntable = of_property_count_elems_of_size(np, "temperature-lookup-table", | |
84 | sizeof(u32)); | |
d36e2fa0 | 85 | if (ntable <= 0) { |
07d243a6 MB |
86 | ret = iio_get_channel_type(gti->channel, &chan_type); |
87 | if (ret || chan_type != IIO_TEMP) | |
88 | dev_notice(dev, | |
89 | "no lookup table, assuming DAC channel returns milliCelcius\n"); | |
d36e2fa0 | 90 | return 0; |
b3aef78f LD |
91 | } |
92 | ||
93 | if (ntable % 2) { | |
94 | dev_err(dev, "Pair of temperature vs ADC read value missing\n"); | |
95 | return -EINVAL; | |
96 | } | |
97 | ||
a86854d0 KC |
98 | gti->lookup_table = devm_kcalloc(dev, |
99 | ntable, sizeof(*gti->lookup_table), | |
100 | GFP_KERNEL); | |
b3aef78f LD |
101 | if (!gti->lookup_table) |
102 | return -ENOMEM; | |
103 | ||
104 | ret = of_property_read_u32_array(np, "temperature-lookup-table", | |
105 | (u32 *)gti->lookup_table, ntable); | |
106 | if (ret < 0) { | |
107 | dev_err(dev, "Failed to read temperature lookup table: %d\n", | |
108 | ret); | |
109 | return ret; | |
110 | } | |
111 | ||
112 | gti->nlookup_table = ntable / 2; | |
113 | ||
114 | return 0; | |
115 | } | |
116 | ||
117 | static int gadc_thermal_probe(struct platform_device *pdev) | |
118 | { | |
119 | struct gadc_thermal_info *gti; | |
120 | int ret; | |
121 | ||
122 | if (!pdev->dev.of_node) { | |
123 | dev_err(&pdev->dev, "Only DT based supported\n"); | |
124 | return -ENODEV; | |
125 | } | |
126 | ||
127 | gti = devm_kzalloc(&pdev->dev, sizeof(*gti), GFP_KERNEL); | |
128 | if (!gti) | |
129 | return -ENOMEM; | |
130 | ||
d377aba1 | 131 | gti->channel = devm_iio_channel_get(&pdev->dev, "sensor-channel"); |
b3aef78f LD |
132 | if (IS_ERR(gti->channel)) { |
133 | ret = PTR_ERR(gti->channel); | |
86bd20a5 HYW |
134 | if (ret != -EPROBE_DEFER) |
135 | dev_err(&pdev->dev, "IIO channel not found: %d\n", ret); | |
b3aef78f LD |
136 | return ret; |
137 | } | |
138 | ||
c1fde6e1 MB |
139 | ret = gadc_thermal_read_linear_lookup_table(&pdev->dev, gti); |
140 | if (ret < 0) | |
141 | return ret; | |
142 | ||
143 | gti->dev = &pdev->dev; | |
144 | platform_set_drvdata(pdev, gti); | |
145 | ||
d377aba1 DL |
146 | gti->tz_dev = devm_thermal_zone_of_sensor_register(&pdev->dev, 0, gti, |
147 | &gadc_thermal_ops); | |
b3aef78f LD |
148 | if (IS_ERR(gti->tz_dev)) { |
149 | ret = PTR_ERR(gti->tz_dev); | |
86bd20a5 HYW |
150 | if (ret != -EPROBE_DEFER) |
151 | dev_err(&pdev->dev, | |
152 | "Thermal zone sensor register failed: %d\n", | |
153 | ret); | |
d377aba1 | 154 | return ret; |
b3aef78f LD |
155 | } |
156 | ||
b3aef78f LD |
157 | return 0; |
158 | } | |
159 | ||
160 | static const struct of_device_id of_adc_thermal_match[] = { | |
161 | { .compatible = "generic-adc-thermal", }, | |
162 | {}, | |
163 | }; | |
164 | MODULE_DEVICE_TABLE(of, of_adc_thermal_match); | |
165 | ||
166 | static struct platform_driver gadc_thermal_driver = { | |
167 | .driver = { | |
168 | .name = "generic-adc-thermal", | |
169 | .of_match_table = of_adc_thermal_match, | |
170 | }, | |
171 | .probe = gadc_thermal_probe, | |
b3aef78f LD |
172 | }; |
173 | ||
174 | module_platform_driver(gadc_thermal_driver); | |
175 | ||
176 | MODULE_AUTHOR("Laxman Dewangan <ldewangan@nvidia.com>"); | |
177 | MODULE_DESCRIPTION("Generic ADC thermal driver using IIO framework with DT"); | |
178 | MODULE_LICENSE("GPL v2"); |