1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * Generic ADC thermal driver |
4 | * |
5 | * Copyright (C) 2016 NVIDIA CORPORATION. All rights reserved. |
6 | * |
7 | * Author: Laxman Dewangan <ldewangan@nvidia.com> |
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 | #include "thermal_hwmon.h" |
17 | |
18 | struct gadc_thermal_info { |
19 | struct device *dev; |
20 | struct thermal_zone_device *tz_dev; |
21 | struct iio_channel *channel; |
22 | s32 *lookup_table; |
23 | int nlookup_table; |
24 | }; |
25 | |
26 | static int gadc_thermal_adc_to_temp(struct gadc_thermal_info *gti, int val) |
27 | { |
28 | int temp, temp_hi, temp_lo, adc_hi, adc_lo; |
29 | int i; |
30 | |
31 | if (!gti->lookup_table) |
32 | return val; |
33 | |
34 | for (i = 0; i < gti->nlookup_table; i++) { |
35 | if (val >= gti->lookup_table[2 * i + 1]) |
36 | break; |
37 | } |
38 | |
39 | if (i == 0) { |
40 | temp = gti->lookup_table[0]; |
41 | } else if (i >= gti->nlookup_table) { |
42 | temp = gti->lookup_table[2 * (gti->nlookup_table - 1)]; |
43 | } else { |
44 | adc_hi = gti->lookup_table[2 * i - 1]; |
45 | adc_lo = gti->lookup_table[2 * i + 1]; |
46 | |
47 | temp_hi = gti->lookup_table[2 * i - 2]; |
48 | temp_lo = gti->lookup_table[2 * i]; |
49 | |
50 | temp = temp_hi + mult_frac(temp_lo - temp_hi, val - adc_hi, |
51 | adc_lo - adc_hi); |
52 | } |
53 | |
54 | return temp; |
55 | } |
56 | |
57 | static int gadc_thermal_get_temp(struct thermal_zone_device *tz, int *temp) |
58 | { |
59 | struct gadc_thermal_info *gti = thermal_zone_device_priv(tzd: tz); |
60 | int val; |
61 | int ret; |
62 | |
63 | ret = iio_read_channel_processed(chan: gti->channel, val: &val); |
64 | if (ret < 0) |
65 | return ret; |
66 | |
67 | *temp = gadc_thermal_adc_to_temp(gti, val); |
68 | |
69 | return 0; |
70 | } |
71 | |
72 | static const struct thermal_zone_device_ops gadc_thermal_ops = { |
73 | .get_temp = gadc_thermal_get_temp, |
74 | }; |
75 | |
76 | static int gadc_thermal_read_linear_lookup_table(struct device *dev, |
77 | struct gadc_thermal_info *gti) |
78 | { |
79 | struct device_node *np = dev->of_node; |
80 | enum iio_chan_type chan_type; |
81 | int ntable; |
82 | int ret; |
83 | |
84 | ntable = of_property_count_elems_of_size(np, propname: "temperature-lookup-table" , |
85 | elem_size: sizeof(u32)); |
86 | if (ntable <= 0) { |
87 | ret = iio_get_channel_type(channel: gti->channel, type: &chan_type); |
88 | if (ret || chan_type != IIO_TEMP) |
89 | dev_notice(dev, |
90 | "no lookup table, assuming DAC channel returns milliCelcius\n" ); |
91 | return 0; |
92 | } |
93 | |
94 | if (ntable % 2) { |
95 | dev_err(dev, "Pair of temperature vs ADC read value missing\n" ); |
96 | return -EINVAL; |
97 | } |
98 | |
99 | gti->lookup_table = devm_kcalloc(dev, |
100 | n: ntable, size: sizeof(*gti->lookup_table), |
101 | GFP_KERNEL); |
102 | if (!gti->lookup_table) |
103 | return -ENOMEM; |
104 | |
105 | ret = of_property_read_u32_array(np, propname: "temperature-lookup-table" , |
106 | out_values: (u32 *)gti->lookup_table, sz: ntable); |
107 | if (ret < 0) { |
108 | dev_err(dev, "Failed to read temperature lookup table: %d\n" , |
109 | ret); |
110 | return ret; |
111 | } |
112 | |
113 | gti->nlookup_table = ntable / 2; |
114 | |
115 | return 0; |
116 | } |
117 | |
118 | static int gadc_thermal_probe(struct platform_device *pdev) |
119 | { |
120 | struct gadc_thermal_info *gti; |
121 | int ret; |
122 | |
123 | if (!pdev->dev.of_node) { |
124 | dev_err(&pdev->dev, "Only DT based supported\n" ); |
125 | return -ENODEV; |
126 | } |
127 | |
128 | gti = devm_kzalloc(dev: &pdev->dev, size: sizeof(*gti), GFP_KERNEL); |
129 | if (!gti) |
130 | return -ENOMEM; |
131 | |
132 | gti->channel = devm_iio_channel_get(dev: &pdev->dev, consumer_channel: "sensor-channel" ); |
133 | if (IS_ERR(ptr: gti->channel)) { |
134 | ret = PTR_ERR(ptr: gti->channel); |
135 | if (ret != -EPROBE_DEFER) |
136 | dev_err(&pdev->dev, "IIO channel not found: %d\n" , ret); |
137 | return ret; |
138 | } |
139 | |
140 | ret = gadc_thermal_read_linear_lookup_table(dev: &pdev->dev, gti); |
141 | if (ret < 0) |
142 | return ret; |
143 | |
144 | gti->dev = &pdev->dev; |
145 | |
146 | gti->tz_dev = devm_thermal_of_zone_register(dev: &pdev->dev, id: 0, data: gti, |
147 | ops: &gadc_thermal_ops); |
148 | if (IS_ERR(ptr: gti->tz_dev)) { |
149 | ret = PTR_ERR(ptr: gti->tz_dev); |
150 | if (ret != -EPROBE_DEFER) |
151 | dev_err(&pdev->dev, |
152 | "Thermal zone sensor register failed: %d\n" , |
153 | ret); |
154 | return ret; |
155 | } |
156 | |
157 | devm_thermal_add_hwmon_sysfs(dev: &pdev->dev, tz: gti->tz_dev); |
158 | |
159 | return 0; |
160 | } |
161 | |
162 | static const struct of_device_id of_adc_thermal_match[] = { |
163 | { .compatible = "generic-adc-thermal" , }, |
164 | {}, |
165 | }; |
166 | MODULE_DEVICE_TABLE(of, of_adc_thermal_match); |
167 | |
168 | static struct platform_driver gadc_thermal_driver = { |
169 | .driver = { |
170 | .name = "generic-adc-thermal" , |
171 | .of_match_table = of_adc_thermal_match, |
172 | }, |
173 | .probe = gadc_thermal_probe, |
174 | }; |
175 | |
176 | module_platform_driver(gadc_thermal_driver); |
177 | |
178 | MODULE_AUTHOR("Laxman Dewangan <ldewangan@nvidia.com>" ); |
179 | MODULE_DESCRIPTION("Generic ADC thermal driver using IIO framework with DT" ); |
180 | MODULE_LICENSE("GPL v2" ); |
181 | |