diff options
Diffstat (limited to 'drivers/thermal/thermal-generic-adc.c')
| -rw-r--r-- | drivers/thermal/thermal-generic-adc.c | 178 |
1 files changed, 178 insertions, 0 deletions
diff --git a/drivers/thermal/thermal-generic-adc.c b/drivers/thermal/thermal-generic-adc.c new file mode 100644 index 000000000..323e273e3 --- /dev/null +++ b/drivers/thermal/thermal-generic-adc.c @@ -0,0 +1,178 @@ +// 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> + +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 = tz->devdata; + 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_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; + } + + 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"); |