/* * 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 * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. * */ #include <linux/kernel.h> #include <linux/module.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 */ /* 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 = 1; } 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 * an 1 mOhm sense resistor, in mA. */ val = val * 20; 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_show_value(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 snprintf(buf, PAGE_SIZE, "%d\n", value); } /* * Input voltages. */ static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, ltc4151_show_value, NULL, LTC4151_VIN_H); static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, ltc4151_show_value, NULL, LTC4151_ADIN_H); /* Currents (via sense resistor) */ static SENSOR_DEVICE_ATTR(curr1_input, S_IRUGO, ltc4151_show_value, NULL, 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, const struct i2c_device_id *id) { struct i2c_adapter *adapter = client->adapter; struct device *dev = &client->dev; struct ltc4151_data *data; struct device *hwmon_dev; if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)) return -ENODEV; data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL); if (!data) return -ENOMEM; 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); /* This is the driver that will be inserted */ static struct i2c_driver ltc4151_driver = { .driver = { .name = "ltc4151", }, .probe = 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");