// SPDX-License-Identifier: GPL-2.0-or-later /* * Driver for Linear Technology LTC4261 I2C Negative Voltage Hot Swap Controller * * Copyright (C) 2010 Ericsson AB. * * Derived from: * * Driver for Linear Technology LTC4245 I2C Multiple Supply Hot Swap Controller * Copyright (C) 2008 Ira W. Snyder <iws@ovro.caltech.edu> * * Datasheet: http://cds.linear.com/docs/Datasheet/42612fb.pdf */ #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 LTC4261_STATUS 0x00 /* readonly */ #define LTC4261_FAULT 0x01 #define LTC4261_ALERT 0x02 #define LTC4261_CONTROL 0x03 #define LTC4261_SENSE_H 0x04 #define LTC4261_SENSE_L 0x05 #define LTC4261_ADIN2_H 0x06 #define LTC4261_ADIN2_L 0x07 #define LTC4261_ADIN_H 0x08 #define LTC4261_ADIN_L 0x09 /* * Fault register bits */ #define FAULT_OV (1<<0) #define FAULT_UV (1<<1) #define FAULT_OC (1<<2) struct ltc4261_data { struct i2c_client *client; struct mutex update_lock; bool valid; unsigned long last_updated; /* in jiffies */ /* Registers */ u8 regs[10]; }; static struct ltc4261_data *ltc4261_update_device(struct device *dev) { struct ltc4261_data *data = dev_get_drvdata(dev); struct i2c_client *client = data->client; struct ltc4261_data *ret = data; mutex_lock(&data->update_lock); if (time_after(jiffies, data->last_updated + HZ / 4) || !data->valid) { int i; /* Read registers -- 0x00 to 0x09 */ 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); data->valid = 0; 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 or mA */ static int ltc4261_get_value(struct ltc4261_data *data, u8 reg) { u32 val; val = (data->regs[reg] << 2) + (data->regs[reg + 1] >> 6); switch (reg) { case LTC4261_ADIN_H: case LTC4261_ADIN2_H: /* 2.5mV resolution. Convert to mV. */ val = val * 25 / 10; break; case LTC4261_SENSE_H: /* * 62.5uV 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 * 625 / 10; break; default: /* If we get here, the developer messed up */ WARN_ON_ONCE(1); val = 0; break; } return val; } static ssize_t ltc4261_value_show(struct device *dev, struct device_attribute *da, char *buf) { struct sensor_device_attribute *attr = to_sensor_dev_attr(da); struct ltc4261_data *data = ltc4261_update_device(dev); int value; if (IS_ERR(data)) return PTR_ERR(data); value = ltc4261_get_value(data, attr->index); return snprintf(buf, PAGE_SIZE, "%d\n", value); } static ssize_t ltc4261_bool_show(struct device *dev, struct device_attribute *da, char *buf) { struct sensor_device_attribute *attr = to_sensor_dev_attr(da); struct ltc4261_data *data = ltc4261_update_device(dev); u8 fault; if (IS_ERR(data)) return PTR_ERR(data); fault = data->regs[LTC4261_FAULT] & attr->index; if (fault) /* Clear reported faults in chip register */ i2c_smbus_write_byte_data(data->client, LTC4261_FAULT, ~fault); return snprintf(buf, PAGE_SIZE, "%d\n", fault ? 1 : 0); } /* * Input voltages. */ static SENSOR_DEVICE_ATTR_RO(in1_input, ltc4261_value, LTC4261_ADIN_H); static SENSOR_DEVICE_ATTR_RO(in2_input, ltc4261_value, LTC4261_ADIN2_H); /* * Voltage alarms. The chip has only one set of voltage alarm status bits, * triggered by input voltage alarms. In many designs, those alarms are * associated with the ADIN2 sensor, due to the proximity of the ADIN2 pin * to the OV pin. ADIN2 is, however, not available on all chip variants. * To ensure that the alarm condition is reported to the user, report it * with both voltage sensors. */ static SENSOR_DEVICE_ATTR_RO(in1_min_alarm, ltc4261_bool, FAULT_UV); static SENSOR_DEVICE_ATTR_RO(in1_max_alarm, ltc4261_bool, FAULT_OV); static SENSOR_DEVICE_ATTR_RO(in2_min_alarm, ltc4261_bool, FAULT_UV); static SENSOR_DEVICE_ATTR_RO(in2_max_alarm, ltc4261_bool, FAULT_OV); /* Currents (via sense resistor) */ static SENSOR_DEVICE_ATTR_RO(curr1_input, ltc4261_value, LTC4261_SENSE_H); /* Overcurrent alarm */ static SENSOR_DEVICE_ATTR_RO(curr1_max_alarm, ltc4261_bool, FAULT_OC); static struct attribute *ltc4261_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_min_alarm.dev_attr.attr, &sensor_dev_attr_in2_max_alarm.dev_attr.attr, &sensor_dev_attr_curr1_input.dev_attr.attr, &sensor_dev_attr_curr1_max_alarm.dev_attr.attr, NULL, }; ATTRIBUTE_GROUPS(ltc4261); static int ltc4261_probe(struct i2c_client *client, const struct i2c_device_id *id) { struct i2c_adapter *adapter = client->adapter; struct device *dev = &client->dev; struct ltc4261_data *data; struct device *hwmon_dev; if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)) return -ENODEV; if (i2c_smbus_read_byte_data(client, LTC4261_STATUS) < 0) { dev_err(dev, "Failed to read status register\n"); return -ENODEV; } data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL); if (!data) return -ENOMEM; data->client = client; mutex_init(&data->update_lock); /* Clear faults */ i2c_smbus_write_byte_data(client, LTC4261_FAULT, 0x00); hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name, data, ltc4261_groups); return PTR_ERR_OR_ZERO(hwmon_dev); } static const struct i2c_device_id ltc4261_id[] = { {"ltc4261", 0}, {} }; MODULE_DEVICE_TABLE(i2c, ltc4261_id); /* This is the driver that will be inserted */ static struct i2c_driver ltc4261_driver = { .driver = { .name = "ltc4261", }, .probe = ltc4261_probe, .id_table = ltc4261_id, }; module_i2c_driver(ltc4261_driver); MODULE_AUTHOR("Guenter Roeck <linux@roeck-us.net>"); MODULE_DESCRIPTION("LTC4261 driver"); MODULE_LICENSE("GPL");