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