/* * Generic ADC thermal driver * * Copyright (C) 2016 NVIDIA CORPORATION. All rights reserved. * * Author: Laxman Dewangan <ldewangan@nvidia.com> * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */ #include <linux/iio/consumer.h> #include <linux/kernel.h> #include <linux/module.h> #include <linux/platform_device.h> #include <linux/slab.h> #include <linux/thermal.h> struct gadc_thermal_info { struct device *dev; struct thermal_zone_device *tz_dev; struct iio_channel *channel; s32 *lookup_table; int nlookup_table; }; static int gadc_thermal_adc_to_temp(struct gadc_thermal_info *gti, int val) { int temp, adc_hi, adc_lo; int i; for (i = 0; i < gti->nlookup_table; i++) { if (val >= gti->lookup_table[2 * i + 1]) break; } if (i == 0) { temp = gti->lookup_table[0]; } else if (i >= (gti->nlookup_table - 1)) { temp = gti->lookup_table[2 * (gti->nlookup_table - 1)]; } else { adc_hi = gti->lookup_table[2 * i - 1]; adc_lo = gti->lookup_table[2 * i + 1]; temp = gti->lookup_table[2 * i]; temp -= ((val - adc_lo) * 1000) / (adc_hi - adc_lo); } return temp; } static int gadc_thermal_get_temp(void *data, int *temp) { struct gadc_thermal_info *gti = data; int val; int ret; ret = iio_read_channel_processed(gti->channel, &val); if (ret < 0) { dev_err(gti->dev, "IIO channel read failed %d\n", ret); return ret; } *temp = gadc_thermal_adc_to_temp(gti, val); return 0; } static const struct thermal_zone_of_device_ops gadc_thermal_ops = { .get_temp = gadc_thermal_get_temp, }; static int gadc_thermal_read_linear_lookup_table(struct device *dev, struct gadc_thermal_info *gti) { struct device_node *np = dev->of_node; int ntable; int ret; ntable = of_property_count_elems_of_size(np, "temperature-lookup-table", sizeof(u32)); if (ntable < 0) { dev_err(dev, "Lookup table is not provided\n"); return ntable; } if (ntable % 2) { dev_err(dev, "Pair of temperature vs ADC read value missing\n"); return -EINVAL; } gti->lookup_table = devm_kzalloc(dev, sizeof(*gti->lookup_table) * ntable, GFP_KERNEL); if (!gti->lookup_table) return -ENOMEM; ret = of_property_read_u32_array(np, "temperature-lookup-table", (u32 *)gti->lookup_table, ntable); if (ret < 0) { dev_err(dev, "Failed to read temperature lookup table: %d\n", ret); return ret; } gti->nlookup_table = ntable / 2; return 0; } static int gadc_thermal_probe(struct platform_device *pdev) { struct gadc_thermal_info *gti; int ret; if (!pdev->dev.of_node) { dev_err(&pdev->dev, "Only DT based supported\n"); return -ENODEV; } gti = devm_kzalloc(&pdev->dev, sizeof(*gti), GFP_KERNEL); if (!gti) return -ENOMEM; ret = gadc_thermal_read_linear_lookup_table(&pdev->dev, gti); if (ret < 0) return ret; gti->dev = &pdev->dev; platform_set_drvdata(pdev, gti); gti->channel = devm_iio_channel_get(&pdev->dev, "sensor-channel"); if (IS_ERR(gti->channel)) { ret = PTR_ERR(gti->channel); dev_err(&pdev->dev, "IIO channel not found: %d\n", ret); return ret; } gti->tz_dev = devm_thermal_zone_of_sensor_register(&pdev->dev, 0, gti, &gadc_thermal_ops); if (IS_ERR(gti->tz_dev)) { ret = PTR_ERR(gti->tz_dev); dev_err(&pdev->dev, "Thermal zone sensor register failed: %d\n", ret); return ret; } return 0; } static const struct of_device_id of_adc_thermal_match[] = { { .compatible = "generic-adc-thermal", }, {}, }; MODULE_DEVICE_TABLE(of, of_adc_thermal_match); static struct platform_driver gadc_thermal_driver = { .driver = { .name = "generic-adc-thermal", .of_match_table = of_adc_thermal_match, }, .probe = gadc_thermal_probe, }; module_platform_driver(gadc_thermal_driver); MODULE_AUTHOR("Laxman Dewangan <ldewangan@nvidia.com>"); MODULE_DESCRIPTION("Generic ADC thermal driver using IIO framework with DT"); MODULE_LICENSE("GPL v2");