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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
18struct 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
26static 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
57static int gadc_thermal_get_temp(struct thermal_zone_device *tz, int *temp)
58{
59 struct gadc_thermal_info *gti = thermal_zone_device_priv(tz);
60 int val;
61 int ret;
62
63 ret = iio_read_channel_processed(gti->channel, &val);
64 if (ret < 0)
65 return ret;
66
67 *temp = gadc_thermal_adc_to_temp(gti, val);
68
69 return 0;
70}
71
72static const struct thermal_zone_device_ops gadc_thermal_ops = {
73 .get_temp = gadc_thermal_get_temp,
74};
75
76static 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, "temperature-lookup-table",
85 sizeof(u32));
86 if (ntable <= 0) {
87 ret = iio_get_channel_type(gti->channel, &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 ntable, sizeof(*gti->lookup_table),
101 GFP_KERNEL);
102 if (!gti->lookup_table)
103 return -ENOMEM;
104
105 ret = of_property_read_u32_array(np, "temperature-lookup-table",
106 (u32 *)gti->lookup_table, 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
118static int gadc_thermal_probe(struct platform_device *pdev)
119{
120 struct device *dev = &pdev->dev;
121 struct gadc_thermal_info *gti;
122 int ret;
123
124 if (!dev->of_node) {
125 dev_err(dev, "Only DT based supported\n");
126 return -ENODEV;
127 }
128
129 gti = devm_kzalloc(dev, sizeof(*gti), GFP_KERNEL);
130 if (!gti)
131 return -ENOMEM;
132
133 gti->channel = devm_iio_channel_get(dev, "sensor-channel");
134 if (IS_ERR(gti->channel))
135 return dev_err_probe(dev, PTR_ERR(gti->channel), "IIO channel not found\n");
136
137 ret = gadc_thermal_read_linear_lookup_table(dev, gti);
138 if (ret < 0)
139 return ret;
140
141 gti->dev = dev;
142
143 gti->tz_dev = devm_thermal_of_zone_register(dev, 0, gti,
144 &gadc_thermal_ops);
145 if (IS_ERR(gti->tz_dev)) {
146 ret = PTR_ERR(gti->tz_dev);
147 if (ret != -EPROBE_DEFER)
148 dev_err(dev,
149 "Thermal zone sensor register failed: %d\n",
150 ret);
151 return ret;
152 }
153
154 devm_thermal_add_hwmon_sysfs(dev, gti->tz_dev);
155
156 return 0;
157}
158
159static const struct of_device_id of_adc_thermal_match[] = {
160 { .compatible = "generic-adc-thermal", },
161 {},
162};
163MODULE_DEVICE_TABLE(of, of_adc_thermal_match);
164
165static struct platform_driver gadc_thermal_driver = {
166 .driver = {
167 .name = "generic-adc-thermal",
168 .of_match_table = of_adc_thermal_match,
169 },
170 .probe = gadc_thermal_probe,
171};
172
173module_platform_driver(gadc_thermal_driver);
174
175MODULE_AUTHOR("Laxman Dewangan <ldewangan@nvidia.com>");
176MODULE_DESCRIPTION("Generic ADC thermal driver using IIO framework with DT");
177MODULE_LICENSE("GPL v2");
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
16struct 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
24static int gadc_thermal_adc_to_temp(struct gadc_thermal_info *gti, int val)
25{
26 int temp, temp_hi, temp_lo, adc_hi, adc_lo;
27 int i;
28
29 if (!gti->lookup_table)
30 return val;
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
55static 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
71static const struct thermal_zone_of_device_ops gadc_thermal_ops = {
72 .get_temp = gadc_thermal_get_temp,
73};
74
75static 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_notice(dev, "no lookup table, assuming DAC channel returns milliCelcius\n");
86 return 0;
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_kcalloc(dev,
95 ntable, sizeof(*gti->lookup_table),
96 GFP_KERNEL);
97 if (!gti->lookup_table)
98 return -ENOMEM;
99
100 ret = of_property_read_u32_array(np, "temperature-lookup-table",
101 (u32 *)gti->lookup_table, ntable);
102 if (ret < 0) {
103 dev_err(dev, "Failed to read temperature lookup table: %d\n",
104 ret);
105 return ret;
106 }
107
108 gti->nlookup_table = ntable / 2;
109
110 return 0;
111}
112
113static int gadc_thermal_probe(struct platform_device *pdev)
114{
115 struct gadc_thermal_info *gti;
116 int ret;
117
118 if (!pdev->dev.of_node) {
119 dev_err(&pdev->dev, "Only DT based supported\n");
120 return -ENODEV;
121 }
122
123 gti = devm_kzalloc(&pdev->dev, sizeof(*gti), GFP_KERNEL);
124 if (!gti)
125 return -ENOMEM;
126
127 ret = gadc_thermal_read_linear_lookup_table(&pdev->dev, gti);
128 if (ret < 0)
129 return ret;
130
131 gti->dev = &pdev->dev;
132 platform_set_drvdata(pdev, gti);
133
134 gti->channel = devm_iio_channel_get(&pdev->dev, "sensor-channel");
135 if (IS_ERR(gti->channel)) {
136 ret = PTR_ERR(gti->channel);
137 dev_err(&pdev->dev, "IIO channel not found: %d\n", ret);
138 return ret;
139 }
140
141 gti->tz_dev = devm_thermal_zone_of_sensor_register(&pdev->dev, 0, gti,
142 &gadc_thermal_ops);
143 if (IS_ERR(gti->tz_dev)) {
144 ret = PTR_ERR(gti->tz_dev);
145 dev_err(&pdev->dev, "Thermal zone sensor register failed: %d\n",
146 ret);
147 return ret;
148 }
149
150 return 0;
151}
152
153static const struct of_device_id of_adc_thermal_match[] = {
154 { .compatible = "generic-adc-thermal", },
155 {},
156};
157MODULE_DEVICE_TABLE(of, of_adc_thermal_match);
158
159static struct platform_driver gadc_thermal_driver = {
160 .driver = {
161 .name = "generic-adc-thermal",
162 .of_match_table = of_adc_thermal_match,
163 },
164 .probe = gadc_thermal_probe,
165};
166
167module_platform_driver(gadc_thermal_driver);
168
169MODULE_AUTHOR("Laxman Dewangan <ldewangan@nvidia.com>");
170MODULE_DESCRIPTION("Generic ADC thermal driver using IIO framework with DT");
171MODULE_LICENSE("GPL v2");