diff options
Diffstat (limited to 'drivers/hwmon/ltc4261.c')
| -rw-r--r-- | drivers/hwmon/ltc4261.c | 266 |
1 files changed, 266 insertions, 0 deletions
diff --git a/drivers/hwmon/ltc4261.c b/drivers/hwmon/ltc4261.c new file mode 100644 index 000000000..0becd6984 --- /dev/null +++ b/drivers/hwmon/ltc4261.c @@ -0,0 +1,266 @@ +/* + * 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 + * + * 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 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_show_value(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_show_bool(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(in1_input, S_IRUGO, ltc4261_show_value, NULL, + LTC4261_ADIN_H); +static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, ltc4261_show_value, NULL, + 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(in1_min_alarm, S_IRUGO, ltc4261_show_bool, NULL, + FAULT_UV); +static SENSOR_DEVICE_ATTR(in1_max_alarm, S_IRUGO, ltc4261_show_bool, NULL, + FAULT_OV); +static SENSOR_DEVICE_ATTR(in2_min_alarm, S_IRUGO, ltc4261_show_bool, NULL, + FAULT_UV); +static SENSOR_DEVICE_ATTR(in2_max_alarm, S_IRUGO, ltc4261_show_bool, NULL, + FAULT_OV); + +/* Currents (via sense resistor) */ +static SENSOR_DEVICE_ATTR(curr1_input, S_IRUGO, ltc4261_show_value, NULL, + LTC4261_SENSE_H); + +/* Overcurrent alarm */ +static SENSOR_DEVICE_ATTR(curr1_max_alarm, S_IRUGO, ltc4261_show_bool, NULL, + 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"); |