/* * Driver for Linear Technology LTC4260 I2C Positive Voltage Hot Swap Controller * * Copyright (c) 2014 Guenter Roeck * * 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. */ #include <linux/kernel.h> #include <linux/module.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> #include <linux/regmap.h> /* chip registers */ #define LTC4260_CONTROL 0x00 #define LTC4260_ALERT 0x01 #define LTC4260_STATUS 0x02 #define LTC4260_FAULT 0x03 #define LTC4260_SENSE 0x04 #define LTC4260_SOURCE 0x05 #define LTC4260_ADIN 0x06 /* * Fault register bits */ #define FAULT_OV (1 << 0) #define FAULT_UV (1 << 1) #define FAULT_OC (1 << 2) #define FAULT_POWER_BAD (1 << 3) #define FAULT_FET_SHORT (1 << 5) /* Return the voltage from the given register in mV or mA */ static int ltc4260_get_value(struct device *dev, u8 reg) { struct regmap *regmap = dev_get_drvdata(dev); unsigned int val; int ret; ret = regmap_read(regmap, reg, &val); if (ret < 0) return ret; switch (reg) { case LTC4260_ADIN: /* 10 mV resolution. Convert to mV. */ val = val * 10; break; case LTC4260_SOURCE: /* 400 mV resolution. Convert to mV. */ val = val * 400; break; case LTC4260_SENSE: /* * 300 uV resolution. Convert to current as measured with * an 1 mOhm sense resistor, in mA. If a different sense * resistor is installed, calculate the actual current by * dividing the reported current by the sense resistor value * in mOhm. */ val = val * 300; break; default: return -EINVAL; } return val; } static ssize_t ltc4260_show_value(struct device *dev, struct device_attribute *da, char *buf) { struct sensor_device_attribute *attr = to_sensor_dev_attr(da); int value; value = ltc4260_get_value(dev, attr->index); if (value < 0) return value; return snprintf(buf, PAGE_SIZE, "%d\n", value); } static ssize_t ltc4260_show_bool(struct device *dev, struct device_attribute *da, char *buf) { struct sensor_device_attribute *attr = to_sensor_dev_attr(da); struct regmap *regmap = dev_get_drvdata(dev); unsigned int fault; int ret; ret = regmap_read(regmap, LTC4260_FAULT, &fault); if (ret < 0) return ret; fault &= attr->index; if (fault) /* Clear reported faults in chip register */ regmap_update_bits(regmap, LTC4260_FAULT, attr->index, 0); return snprintf(buf, PAGE_SIZE, "%d\n", !!fault); } /* Voltages */ static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, ltc4260_show_value, NULL, LTC4260_SOURCE); static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, ltc4260_show_value, NULL, LTC4260_ADIN); /* * Voltage alarms * UV/OV faults are associated with the input voltage, and the POWER BAD and * FET SHORT faults are associated with the output voltage. */ static SENSOR_DEVICE_ATTR(in1_min_alarm, S_IRUGO, ltc4260_show_bool, NULL, FAULT_UV); static SENSOR_DEVICE_ATTR(in1_max_alarm, S_IRUGO, ltc4260_show_bool, NULL, FAULT_OV); static SENSOR_DEVICE_ATTR(in2_alarm, S_IRUGO, ltc4260_show_bool, NULL, FAULT_POWER_BAD | FAULT_FET_SHORT); /* Current (via sense resistor) */ static SENSOR_DEVICE_ATTR(curr1_input, S_IRUGO, ltc4260_show_value, NULL, LTC4260_SENSE); /* Overcurrent alarm */ static SENSOR_DEVICE_ATTR(curr1_max_alarm, S_IRUGO, ltc4260_show_bool, NULL, FAULT_OC); static struct attribute *ltc4260_attrs[] = { &sensor_dev_attr_in1_input.dev_attr.attr, &sensor_dev_attr_in1_min_alarm.dev_attr.attr, &sensor_dev_attr_in1_max_alarm.dev_attr.attr, &sensor_dev_attr_in2_input.dev_attr.attr, &sensor_dev_attr_in2_alarm.dev_attr.attr, &sensor_dev_attr_curr1_input.dev_attr.attr, &sensor_dev_attr_curr1_max_alarm.dev_attr.attr, NULL, }; ATTRIBUTE_GROUPS(ltc4260); static const struct regmap_config ltc4260_regmap_config = { .reg_bits = 8, .val_bits = 8, .max_register = LTC4260_ADIN, }; static int ltc4260_probe(struct i2c_client *client, const struct i2c_device_id *id) { struct device *dev = &client->dev; struct device *hwmon_dev; struct regmap *regmap; regmap = devm_regmap_init_i2c(client, <c4260_regmap_config); if (IS_ERR(regmap)) { dev_err(dev, "failed to allocate register map\n"); return PTR_ERR(regmap); } /* Clear faults */ regmap_write(regmap, LTC4260_FAULT, 0x00); hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name, regmap, ltc4260_groups); return PTR_ERR_OR_ZERO(hwmon_dev); } static const struct i2c_device_id ltc4260_id[] = { {"ltc4260", 0}, { } }; MODULE_DEVICE_TABLE(i2c, ltc4260_id); static struct i2c_driver ltc4260_driver = { .driver = { .name = "ltc4260", }, .probe = ltc4260_probe, .id_table = ltc4260_id, }; module_i2c_driver(ltc4260_driver); MODULE_AUTHOR("Guenter Roeck <linux@roeck-us.net>"); MODULE_DESCRIPTION("LTC4260 driver"); MODULE_LICENSE("GPL");