| 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, temp_hi, temp_lo, 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) { |
| 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 | |
| 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"); |