156 lines
3.8 KiB
C
156 lines
3.8 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* max31722 - hwmon driver for Maxim Integrated MAX31722/MAX31723 SPI
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* digital thermometer and thermostats.
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*
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* Copyright (c) 2016, Intel Corporation.
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*/
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#include <linux/hwmon.h>
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#include <linux/hwmon-sysfs.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/spi/spi.h>
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#define MAX31722_REG_CFG 0x00
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#define MAX31722_REG_TEMP_LSB 0x01
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#define MAX31722_MODE_CONTINUOUS 0x00
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#define MAX31722_MODE_STANDBY 0x01
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#define MAX31722_MODE_MASK 0xFE
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#define MAX31722_RESOLUTION_12BIT 0x06
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#define MAX31722_WRITE_MASK 0x80
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struct max31722_data {
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struct device *hwmon_dev;
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struct spi_device *spi_device;
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u8 mode;
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};
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static int max31722_set_mode(struct max31722_data *data, u8 mode)
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{
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int ret;
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struct spi_device *spi = data->spi_device;
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u8 buf[2] = {
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MAX31722_REG_CFG | MAX31722_WRITE_MASK,
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(data->mode & MAX31722_MODE_MASK) | mode
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};
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ret = spi_write(spi, &buf, sizeof(buf));
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if (ret < 0) {
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dev_err(&spi->dev, "failed to set sensor mode.\n");
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return ret;
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}
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data->mode = (data->mode & MAX31722_MODE_MASK) | mode;
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return 0;
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}
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static ssize_t max31722_temp_show(struct device *dev,
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struct device_attribute *attr, char *buf)
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{
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ssize_t ret;
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struct max31722_data *data = dev_get_drvdata(dev);
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ret = spi_w8r16(data->spi_device, MAX31722_REG_TEMP_LSB);
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if (ret < 0)
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return ret;
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/* Keep 12 bits and multiply by the scale of 62.5 millidegrees/bit. */
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return sprintf(buf, "%d\n", (s16)le16_to_cpu(ret) * 125 / 32);
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}
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static SENSOR_DEVICE_ATTR_RO(temp1_input, max31722_temp, 0);
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static struct attribute *max31722_attrs[] = {
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&sensor_dev_attr_temp1_input.dev_attr.attr,
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NULL,
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};
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ATTRIBUTE_GROUPS(max31722);
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static int max31722_probe(struct spi_device *spi)
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{
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int ret;
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struct max31722_data *data;
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data = devm_kzalloc(&spi->dev, sizeof(*data), GFP_KERNEL);
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if (!data)
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return -ENOMEM;
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spi_set_drvdata(spi, data);
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data->spi_device = spi;
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/*
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* Set SD bit to 0 so we can have continuous measurements.
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* Set resolution to 12 bits for maximum precision.
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*/
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data->mode = MAX31722_MODE_CONTINUOUS | MAX31722_RESOLUTION_12BIT;
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ret = max31722_set_mode(data, MAX31722_MODE_CONTINUOUS);
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if (ret < 0)
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return ret;
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data->hwmon_dev = hwmon_device_register_with_groups(&spi->dev,
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spi->modalias,
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data,
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max31722_groups);
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if (IS_ERR(data->hwmon_dev)) {
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max31722_set_mode(data, MAX31722_MODE_STANDBY);
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return PTR_ERR(data->hwmon_dev);
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}
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return 0;
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}
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static void max31722_remove(struct spi_device *spi)
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{
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struct max31722_data *data = spi_get_drvdata(spi);
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int ret;
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hwmon_device_unregister(data->hwmon_dev);
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ret = max31722_set_mode(data, MAX31722_MODE_STANDBY);
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if (ret)
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/* There is nothing we can do about this ... */
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dev_warn(&spi->dev, "Failed to put device in stand-by mode\n");
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}
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static int max31722_suspend(struct device *dev)
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{
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struct spi_device *spi_device = to_spi_device(dev);
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struct max31722_data *data = spi_get_drvdata(spi_device);
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return max31722_set_mode(data, MAX31722_MODE_STANDBY);
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}
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static int max31722_resume(struct device *dev)
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{
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struct spi_device *spi_device = to_spi_device(dev);
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struct max31722_data *data = spi_get_drvdata(spi_device);
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return max31722_set_mode(data, MAX31722_MODE_CONTINUOUS);
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}
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static DEFINE_SIMPLE_DEV_PM_OPS(max31722_pm_ops, max31722_suspend, max31722_resume);
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static const struct spi_device_id max31722_spi_id[] = {
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{"max31722", 0},
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{"max31723", 0},
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{}
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};
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MODULE_DEVICE_TABLE(spi, max31722_spi_id);
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static struct spi_driver max31722_driver = {
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.driver = {
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.name = "max31722",
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.pm = pm_sleep_ptr(&max31722_pm_ops),
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},
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.probe = max31722_probe,
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.remove = max31722_remove,
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.id_table = max31722_spi_id,
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};
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module_spi_driver(max31722_driver);
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MODULE_AUTHOR("Tiberiu Breana <tiberiu.a.breana@intel.com>");
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MODULE_DESCRIPTION("max31722 sensor driver");
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MODULE_LICENSE("GPL v2");
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