| // SPDX-License-Identifier: GPL-2.0-only |
| /* |
| * Generic ADC thermal driver |
| * |
| * Copyright (C) 2016 NVIDIA CORPORATION. All rights reserved. |
| * |
| * Author: Laxman Dewangan <ldewangan@nvidia.com> |
| */ |
| #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> |
| |
| #include "thermal_hwmon.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, temp_hi, temp_lo, adc_hi, adc_lo; |
| int i; |
| |
| if (!gti->lookup_table) |
| return val; |
| |
| 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) { |
| 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_hi = gti->lookup_table[2 * i - 2]; |
| temp_lo = gti->lookup_table[2 * i]; |
| |
| temp = temp_hi + mult_frac(temp_lo - temp_hi, val - adc_hi, |
| adc_lo - adc_hi); |
| } |
| |
| return temp; |
| } |
| |
| static int gadc_thermal_get_temp(struct thermal_zone_device *tz, int *temp) |
| { |
| struct gadc_thermal_info *gti = thermal_zone_device_priv(tz); |
| int val; |
| int ret; |
| |
| ret = iio_read_channel_processed(gti->channel, &val); |
| if (ret < 0) |
| return ret; |
| |
| *temp = gadc_thermal_adc_to_temp(gti, val); |
| |
| return 0; |
| } |
| |
| static const struct thermal_zone_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; |
| enum iio_chan_type chan_type; |
| int ntable; |
| int ret; |
| |
| ntable = of_property_count_elems_of_size(np, "temperature-lookup-table", |
| sizeof(u32)); |
| if (ntable <= 0) { |
| ret = iio_get_channel_type(gti->channel, &chan_type); |
| if (ret || chan_type != IIO_TEMP) |
| dev_notice(dev, |
| "no lookup table, assuming DAC channel returns milliCelcius\n"); |
| return 0; |
| } |
| |
| if (ntable % 2) { |
| dev_err(dev, "Pair of temperature vs ADC read value missing\n"); |
| return -EINVAL; |
| } |
| |
| gti->lookup_table = devm_kcalloc(dev, |
| ntable, sizeof(*gti->lookup_table), |
| 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; |
| |
| gti->channel = devm_iio_channel_get(&pdev->dev, "sensor-channel"); |
| if (IS_ERR(gti->channel)) { |
| ret = PTR_ERR(gti->channel); |
| if (ret != -EPROBE_DEFER) |
| dev_err(&pdev->dev, "IIO channel not found: %d\n", ret); |
| return ret; |
| } |
| |
| 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->tz_dev = devm_thermal_of_zone_register(&pdev->dev, 0, gti, |
| &gadc_thermal_ops); |
| if (IS_ERR(gti->tz_dev)) { |
| ret = PTR_ERR(gti->tz_dev); |
| if (ret != -EPROBE_DEFER) |
| dev_err(&pdev->dev, |
| "Thermal zone sensor register failed: %d\n", |
| ret); |
| return ret; |
| } |
| |
| devm_thermal_add_hwmon_sysfs(&pdev->dev, gti->tz_dev); |
| |
| 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"); |