diff options
Diffstat (limited to 'drivers/hwmon/ltc4151.c')
| -rw-r--r-- | drivers/hwmon/ltc4151.c | 256 |
1 files changed, 256 insertions, 0 deletions
diff --git a/drivers/hwmon/ltc4151.c b/drivers/hwmon/ltc4151.c new file mode 100644 index 00000000000..4ac06b75aa6 --- /dev/null +++ b/drivers/hwmon/ltc4151.c @@ -0,0 +1,256 @@ +/* + * 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> + +/* 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 device *hwmon_dev; + + 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 i2c_client *client = to_i2c_client(dev); + struct ltc4151_data *data = i2c_get_clientdata(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_attributes[] = { + &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, +}; + +static const struct attribute_group ltc4151_group = { + .attrs = ltc4151_attributes, +}; + +static int ltc4151_probe(struct i2c_client *client, + const struct i2c_device_id *id) +{ + struct i2c_adapter *adapter = client->adapter; + struct ltc4151_data *data; + int ret; + + if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)) + return -ENODEV; + + data = kzalloc(sizeof(*data), GFP_KERNEL); + if (!data) { + ret = -ENOMEM; + goto out_kzalloc; + } + + i2c_set_clientdata(client, data); + mutex_init(&data->update_lock); + + /* Register sysfs hooks */ + ret = sysfs_create_group(&client->dev.kobj, <c4151_group); + if (ret) + goto out_sysfs_create_group; + + data->hwmon_dev = hwmon_device_register(&client->dev); + if (IS_ERR(data->hwmon_dev)) { + ret = PTR_ERR(data->hwmon_dev); + goto out_hwmon_device_register; + } + + return 0; + +out_hwmon_device_register: + sysfs_remove_group(&client->dev.kobj, <c4151_group); +out_sysfs_create_group: + kfree(data); +out_kzalloc: + return ret; +} + +static int ltc4151_remove(struct i2c_client *client) +{ + struct ltc4151_data *data = i2c_get_clientdata(client); + + hwmon_device_unregister(data->hwmon_dev); + sysfs_remove_group(&client->dev.kobj, <c4151_group); + + kfree(data); + + return 0; +} + +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, + .remove = ltc4151_remove, + .id_table = ltc4151_id, +}; + +static int __init ltc4151_init(void) +{ + return i2c_add_driver(<c4151_driver); +} + +static void __exit ltc4151_exit(void) +{ + i2c_del_driver(<c4151_driver); +} + +MODULE_AUTHOR("Per Dalen <per.dalen@appeartv.com>"); +MODULE_DESCRIPTION("LTC4151 driver"); +MODULE_LICENSE("GPL"); + +module_init(ltc4151_init); +module_exit(ltc4151_exit); |