diff options
Diffstat (limited to 'drivers/hwmon/ltc4151.c')
| -rw-r--r-- | drivers/hwmon/ltc4151.c | 216 |
1 files changed, 216 insertions, 0 deletions
diff --git a/drivers/hwmon/ltc4151.c b/drivers/hwmon/ltc4151.c new file mode 100644 index 000000000..e3ac004c1 --- /dev/null +++ b/drivers/hwmon/ltc4151.c @@ -0,0 +1,216 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Driver for Linear Technology LTC4151 High Voltage I2C Current + * and Voltage Monitor + * + * Copyright (C) 2011 AppearTV AS + * + * Derived from: + * + * Driver for Linear Technology LTC4261 I2C Negative Voltage Hot + * Swap Controller + * Copyright (C) 2010 Ericsson AB. + * + * Datasheet: http://www.linear.com/docs/Datasheet/4151fc.pdf + */ + +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/init.h> +#include <linux/err.h> +#include <linux/slab.h> +#include <linux/i2c.h> +#include <linux/hwmon.h> +#include <linux/hwmon-sysfs.h> +#include <linux/jiffies.h> + +/* chip registers */ +#define LTC4151_SENSE_H 0x00 +#define LTC4151_SENSE_L 0x01 +#define LTC4151_VIN_H 0x02 +#define LTC4151_VIN_L 0x03 +#define LTC4151_ADIN_H 0x04 +#define LTC4151_ADIN_L 0x05 + +struct ltc4151_data { + struct i2c_client *client; + + struct mutex update_lock; + bool valid; + unsigned long last_updated; /* in jiffies */ + unsigned int shunt; /* in micro ohms */ + + /* Registers */ + u8 regs[6]; +}; + +static struct ltc4151_data *ltc4151_update_device(struct device *dev) +{ + struct ltc4151_data *data = dev_get_drvdata(dev); + struct i2c_client *client = data->client; + struct ltc4151_data *ret = data; + + mutex_lock(&data->update_lock); + + /* + * The chip's A/D updates 6 times per second + * (Conversion Rate 6 - 9 Hz) + */ + if (time_after(jiffies, data->last_updated + HZ / 6) || !data->valid) { + int i; + + dev_dbg(&client->dev, "Starting ltc4151 update\n"); + + /* Read all registers */ + for (i = 0; i < ARRAY_SIZE(data->regs); i++) { + int val; + + val = i2c_smbus_read_byte_data(client, i); + if (unlikely(val < 0)) { + dev_dbg(dev, + "Failed to read ADC value: error %d\n", + val); + ret = ERR_PTR(val); + goto abort; + } + data->regs[i] = val; + } + data->last_updated = jiffies; + data->valid = true; + } +abort: + mutex_unlock(&data->update_lock); + return ret; +} + +/* Return the voltage from the given register in mV */ +static int ltc4151_get_value(struct ltc4151_data *data, u8 reg) +{ + u32 val; + + val = (data->regs[reg] << 4) + (data->regs[reg + 1] >> 4); + + switch (reg) { + case LTC4151_ADIN_H: + /* 500uV resolution. Convert to mV. */ + val = val * 500 / 1000; + break; + case LTC4151_SENSE_H: + /* + * 20uV resolution. Convert to current as measured with + * a given sense resistor, in mA. + */ + val = val * 20 * 1000 / data->shunt; + break; + case LTC4151_VIN_H: + /* 25 mV per increment */ + val = val * 25; + break; + default: + /* If we get here, the developer messed up */ + WARN_ON_ONCE(1); + val = 0; + break; + } + + return val; +} + +static ssize_t ltc4151_value_show(struct device *dev, + struct device_attribute *da, char *buf) +{ + struct sensor_device_attribute *attr = to_sensor_dev_attr(da); + struct ltc4151_data *data = ltc4151_update_device(dev); + int value; + + if (IS_ERR(data)) + return PTR_ERR(data); + + value = ltc4151_get_value(data, attr->index); + return sysfs_emit(buf, "%d\n", value); +} + +/* + * Input voltages. + */ +static SENSOR_DEVICE_ATTR_RO(in1_input, ltc4151_value, LTC4151_VIN_H); +static SENSOR_DEVICE_ATTR_RO(in2_input, ltc4151_value, LTC4151_ADIN_H); + +/* Currents (via sense resistor) */ +static SENSOR_DEVICE_ATTR_RO(curr1_input, ltc4151_value, LTC4151_SENSE_H); + +/* + * Finally, construct an array of pointers to members of the above objects, + * as required for sysfs_create_group() + */ +static struct attribute *ltc4151_attrs[] = { + &sensor_dev_attr_in1_input.dev_attr.attr, + &sensor_dev_attr_in2_input.dev_attr.attr, + + &sensor_dev_attr_curr1_input.dev_attr.attr, + + NULL, +}; +ATTRIBUTE_GROUPS(ltc4151); + +static int ltc4151_probe(struct i2c_client *client) +{ + struct i2c_adapter *adapter = client->adapter; + struct device *dev = &client->dev; + struct ltc4151_data *data; + struct device *hwmon_dev; + u32 shunt; + + if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)) + return -ENODEV; + + data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL); + if (!data) + return -ENOMEM; + + if (of_property_read_u32(client->dev.of_node, + "shunt-resistor-micro-ohms", &shunt)) + shunt = 1000; /* 1 mOhm if not set via DT */ + + if (shunt == 0) + return -EINVAL; + + data->shunt = shunt; + + data->client = client; + mutex_init(&data->update_lock); + + hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name, + data, + ltc4151_groups); + return PTR_ERR_OR_ZERO(hwmon_dev); +} + +static const struct i2c_device_id ltc4151_id[] = { + { "ltc4151", 0 }, + { } +}; +MODULE_DEVICE_TABLE(i2c, ltc4151_id); + +static const struct of_device_id __maybe_unused ltc4151_match[] = { + { .compatible = "lltc,ltc4151" }, + {}, +}; +MODULE_DEVICE_TABLE(of, ltc4151_match); + +/* This is the driver that will be inserted */ +static struct i2c_driver ltc4151_driver = { + .driver = { + .name = "ltc4151", + .of_match_table = of_match_ptr(ltc4151_match), + }, + .probe_new = ltc4151_probe, + .id_table = ltc4151_id, +}; + +module_i2c_driver(ltc4151_driver); + +MODULE_AUTHOR("Per Dalen <per.dalen@appeartv.com>"); +MODULE_DESCRIPTION("LTC4151 driver"); +MODULE_LICENSE("GPL"); |