The LTC2741 and LTC2473 are single voltage monitoring chips. The LTC2473 is similar to the LTC2471 but outputs a signed differential value.
Datasheet: http://cds.linear.com/docs/en/datasheet/24713fb.pdf Signed-off-by: Mike Looijmans <mike.looijm...@topic.nl> --- drivers/hwmon/Kconfig | 10 ++++ drivers/hwmon/Makefile | 1 + drivers/hwmon/ltc2471.c | 127 ++++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 138 insertions(+) create mode 100644 drivers/hwmon/ltc2471.c diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig index fbde226..c9a2a87 100644 --- a/drivers/hwmon/Kconfig +++ b/drivers/hwmon/Kconfig @@ -673,6 +673,16 @@ config SENSORS_LINEAGE This driver can also be built as a module. If so, the module will be called lineage-pem. +config SENSORS_LTC2471 + tristate "Linear Technology LTC2471 and LTC2473" + depends on I2C + help + If you say yes here you get support for Linear Technology LTC2471 + and LTC2473 voltage monitors. + + This driver can also be built as a module. If so, the module will + be called ltc2471. + config SENSORS_LTC2945 tristate "Linear Technology LTC2945" depends on I2C diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile index 58cc3ac..6f60fe7 100644 --- a/drivers/hwmon/Makefile +++ b/drivers/hwmon/Makefile @@ -99,6 +99,7 @@ obj-$(CONFIG_SENSORS_LM93) += lm93.o obj-$(CONFIG_SENSORS_LM95234) += lm95234.o obj-$(CONFIG_SENSORS_LM95241) += lm95241.o obj-$(CONFIG_SENSORS_LM95245) += lm95245.o +obj-$(CONFIG_SENSORS_LTC2471) += ltc2471.o obj-$(CONFIG_SENSORS_LTC2945) += ltc2945.o obj-$(CONFIG_SENSORS_LTC2990) += ltc2990.o obj-$(CONFIG_SENSORS_LTC4151) += ltc4151.o diff --git a/drivers/hwmon/ltc2471.c b/drivers/hwmon/ltc2471.c new file mode 100644 index 0000000..17eaad8 --- /dev/null +++ b/drivers/hwmon/ltc2471.c @@ -0,0 +1,127 @@ +/* + * Driver for Linear Technology LTC2471 and LTC2473 voltage monitors + * The LTC2473 is identical to the 2471, but reports a differential signal. + * + * Copyright (C) 2017 Topic Embedded Products + * Author: Mike Looijmans <mike.looijm...@topic.nl> + * + * License: GPLv2 + */ + +#include <linux/err.h> +#include <linux/hwmon.h> +#include <linux/hwmon-sysfs.h> +#include <linux/i2c.h> +#include <linux/kernel.h> +#include <linux/module.h> + +enum chips { + ltc2471, + ltc2473 +}; + +struct ltc2471_data { + struct i2c_client *i2c; + bool differential; +}; + +/* Reference voltage is 1.25V */ +#define LTC2471_VREF 1250 + +/* Read two bytes from the I2C bus to obtain the ADC result */ +static int ltc2471_get_value(struct i2c_client *i2c) +{ + int ret; + __be16 buf; + + ret = i2c_master_recv(i2c, (char *)&buf, 2); + if (ret < 0) + return ret; + if (ret != 2) + return -EIO; + + /* MSB first */ + return be16_to_cpu(buf); +} + +static ssize_t ltc2471_show_value(struct device *dev, + struct device_attribute *da, char *buf) +{ + struct ltc2471_data *data = dev_get_drvdata(dev); + int value; + + value = ltc2471_get_value(data->i2c); + if (unlikely(value < 0)) + return value; + + if (data->differential) + /* Ranges from -VREF to +VREF with "0" at 0x8000 */ + value = ((s32)LTC2471_VREF * (s32)(value - 0x8000)) >> 15; + else + /* Ranges from 0 to +VREF */ + value = ((u32)LTC2471_VREF * (u32)value) >> 16; + + return snprintf(buf, PAGE_SIZE, "%d\n", value); +} + +static SENSOR_DEVICE_ATTR(in0_input, S_IRUGO, ltc2471_show_value, NULL, 0); + +static struct attribute *ltc2471_attrs[] = { + &sensor_dev_attr_in0_input.dev_attr.attr, + NULL +}; + +ATTRIBUTE_GROUPS(ltc2471); + +static int ltc2471_i2c_probe(struct i2c_client *i2c, + const struct i2c_device_id *id) +{ + int ret; + struct device *hwmon_dev; + struct ltc2471_data *data; + + if (!i2c_check_functionality(i2c->adapter, I2C_FUNC_I2C)) + return -ENODEV; + + data = devm_kzalloc(&i2c->dev, sizeof(struct ltc2471_data), GFP_KERNEL); + if (unlikely(!data)) + return -ENOMEM; + + data->i2c = i2c; + data->differential = (id->driver_data == ltc2473); + + /* Trigger once to start conversion and check if chip is there */ + ret = ltc2471_get_value(i2c); + if (ret < 0) { + dev_err(&i2c->dev, "Cannot read from device.\n"); + return ret; + } + + hwmon_dev = devm_hwmon_device_register_with_groups(&i2c->dev, + i2c->name, + data, + ltc2471_groups); + + return PTR_ERR_OR_ZERO(hwmon_dev); +} + +static const struct i2c_device_id ltc2471_i2c_id[] = { + { "ltc2471", ltc2471 }, + { "ltc2473", ltc2473 }, + {} +}; +MODULE_DEVICE_TABLE(i2c, ltc2471_i2c_id); + +static struct i2c_driver ltc2471_i2c_driver = { + .driver = { + .name = "ltc2471", + }, + .probe = ltc2471_i2c_probe, + .id_table = ltc2471_i2c_id, +}; + +module_i2c_driver(ltc2471_i2c_driver); + +MODULE_DESCRIPTION("LTC2471/LTC2473 Sensor Driver"); +MODULE_AUTHOR("Topic Embedded Products"); +MODULE_LICENSE("GPL v2"); -- 1.9.1
