diff options
Diffstat (limited to 'drivers/hwmon/max31722.c')
| -rw-r--r-- | drivers/hwmon/max31722.c | 156 |
1 files changed, 156 insertions, 0 deletions
diff --git a/drivers/hwmon/max31722.c b/drivers/hwmon/max31722.c new file mode 100644 index 000000000..877c3d7dc --- /dev/null +++ b/drivers/hwmon/max31722.c @@ -0,0 +1,156 @@ +/* + * max31722 - hwmon driver for Maxim Integrated MAX31722/MAX31723 SPI + * digital thermometer and thermostats. + * + * Copyright (c) 2016, Intel Corporation. + * + * This file is subject to the terms and conditions of version 2 of + * the GNU General Public License. See the file COPYING in the main + * directory of this archive for more details. + */ + +#include <linux/hwmon.h> +#include <linux/hwmon-sysfs.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/spi/spi.h> + +#define MAX31722_REG_CFG 0x00 +#define MAX31722_REG_TEMP_LSB 0x01 + +#define MAX31722_MODE_CONTINUOUS 0x00 +#define MAX31722_MODE_STANDBY 0x01 +#define MAX31722_MODE_MASK 0xFE +#define MAX31722_RESOLUTION_12BIT 0x06 +#define MAX31722_WRITE_MASK 0x80 + +struct max31722_data { + struct device *hwmon_dev; + struct spi_device *spi_device; + u8 mode; +}; + +static int max31722_set_mode(struct max31722_data *data, u8 mode) +{ + int ret; + struct spi_device *spi = data->spi_device; + u8 buf[2] = { + MAX31722_REG_CFG | MAX31722_WRITE_MASK, + (data->mode & MAX31722_MODE_MASK) | mode + }; + + ret = spi_write(spi, &buf, sizeof(buf)); + if (ret < 0) { + dev_err(&spi->dev, "failed to set sensor mode.\n"); + return ret; + } + data->mode = (data->mode & MAX31722_MODE_MASK) | mode; + + return 0; +} + +static ssize_t max31722_show_temp(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + ssize_t ret; + struct max31722_data *data = dev_get_drvdata(dev); + + ret = spi_w8r16(data->spi_device, MAX31722_REG_TEMP_LSB); + if (ret < 0) + return ret; + /* Keep 12 bits and multiply by the scale of 62.5 millidegrees/bit. */ + return sprintf(buf, "%d\n", (s16)le16_to_cpu(ret) * 125 / 32); +} + +static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, + max31722_show_temp, NULL, 0); + +static struct attribute *max31722_attrs[] = { + &sensor_dev_attr_temp1_input.dev_attr.attr, + NULL, +}; + +ATTRIBUTE_GROUPS(max31722); + +static int max31722_probe(struct spi_device *spi) +{ + int ret; + struct max31722_data *data; + + data = devm_kzalloc(&spi->dev, sizeof(*data), GFP_KERNEL); + if (!data) + return -ENOMEM; + + spi_set_drvdata(spi, data); + data->spi_device = spi; + /* + * Set SD bit to 0 so we can have continuous measurements. + * Set resolution to 12 bits for maximum precision. + */ + data->mode = MAX31722_MODE_CONTINUOUS | MAX31722_RESOLUTION_12BIT; + ret = max31722_set_mode(data, MAX31722_MODE_CONTINUOUS); + if (ret < 0) + return ret; + + data->hwmon_dev = hwmon_device_register_with_groups(&spi->dev, + spi->modalias, + data, + max31722_groups); + if (IS_ERR(data->hwmon_dev)) { + max31722_set_mode(data, MAX31722_MODE_STANDBY); + return PTR_ERR(data->hwmon_dev); + } + + return 0; +} + +static int max31722_remove(struct spi_device *spi) +{ + struct max31722_data *data = spi_get_drvdata(spi); + + hwmon_device_unregister(data->hwmon_dev); + + return max31722_set_mode(data, MAX31722_MODE_STANDBY); +} + +static int __maybe_unused max31722_suspend(struct device *dev) +{ + struct spi_device *spi_device = to_spi_device(dev); + struct max31722_data *data = spi_get_drvdata(spi_device); + + return max31722_set_mode(data, MAX31722_MODE_STANDBY); +} + +static int __maybe_unused max31722_resume(struct device *dev) +{ + struct spi_device *spi_device = to_spi_device(dev); + struct max31722_data *data = spi_get_drvdata(spi_device); + + return max31722_set_mode(data, MAX31722_MODE_CONTINUOUS); +} + +static SIMPLE_DEV_PM_OPS(max31722_pm_ops, max31722_suspend, max31722_resume); + +static const struct spi_device_id max31722_spi_id[] = { + {"max31722", 0}, + {"max31723", 0}, + {} +}; +MODULE_DEVICE_TABLE(spi, max31722_spi_id); + +static struct spi_driver max31722_driver = { + .driver = { + .name = "max31722", + .pm = &max31722_pm_ops, + }, + .probe = max31722_probe, + .remove = max31722_remove, + .id_table = max31722_spi_id, +}; + +module_spi_driver(max31722_driver); + +MODULE_AUTHOR("Tiberiu Breana <tiberiu.a.breana@intel.com>"); +MODULE_DESCRIPTION("max31722 sensor driver"); +MODULE_LICENSE("GPL v2"); |