diff options
Diffstat (limited to 'drivers/thermal/thermal-generic-adc.c')
| -rw-r--r-- | drivers/thermal/thermal-generic-adc.c | 182 |
1 files changed, 182 insertions, 0 deletions
diff --git a/drivers/thermal/thermal-generic-adc.c b/drivers/thermal/thermal-generic-adc.c new file mode 100644 index 000000000000..73f55d6a1721 --- /dev/null +++ b/drivers/thermal/thermal-generic-adc.c @@ -0,0 +1,182 @@ +/* + * 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 = 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 = 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); + goto sensor_fail; + } + + return 0; + +sensor_fail: + iio_channel_release(gti->channel); + + return ret; +} + +static int gadc_thermal_remove(struct platform_device *pdev) +{ + struct gadc_thermal_info *gti = platform_get_drvdata(pdev); + + thermal_zone_of_sensor_unregister(&pdev->dev, gti->tz_dev); + iio_channel_release(gti->channel); + + 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, + .remove = gadc_thermal_remove, +}; + +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"); |