1 /* 2 * Driver for Linear Technology LTC4151 High Voltage I2C Current 3 * and Voltage Monitor 4 * 5 * Copyright (C) 2011 AppearTV AS 6 * 7 * Derived from: 8 * 9 * Driver for Linear Technology LTC4261 I2C Negative Voltage Hot 10 * Swap Controller 11 * Copyright (C) 2010 Ericsson AB. 12 * 13 * Datasheet: http://www.linear.com/docs/Datasheet/4151fc.pdf 14 * 15 * This program is free software; you can redistribute it and/or modify 16 * it under the terms of the GNU General Public License as published by 17 * the Free Software Foundation; either version 2 of the License, or 18 * (at your option) any later version. 19 * 20 * This program is distributed in the hope that it will be useful, 21 * but WITHOUT ANY WARRANTY; without even the implied warranty of 22 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 23 * GNU General Public License for more details. 24 * 25 * You should have received a copy of the GNU General Public License 26 * along with this program; if not, write to the Free Software 27 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 28 * 29 */ 30 31 #include <linux/kernel.h> 32 #include <linux/module.h> 33 #include <linux/init.h> 34 #include <linux/err.h> 35 #include <linux/slab.h> 36 #include <linux/i2c.h> 37 #include <linux/hwmon.h> 38 #include <linux/hwmon-sysfs.h> 39 #include <linux/jiffies.h> 40 41 /* chip registers */ 42 #define LTC4151_SENSE_H 0x00 43 #define LTC4151_SENSE_L 0x01 44 #define LTC4151_VIN_H 0x02 45 #define LTC4151_VIN_L 0x03 46 #define LTC4151_ADIN_H 0x04 47 #define LTC4151_ADIN_L 0x05 48 49 struct ltc4151_data { 50 struct i2c_client *client; 51 52 struct mutex update_lock; 53 bool valid; 54 unsigned long last_updated; /* in jiffies */ 55 56 /* Registers */ 57 u8 regs[6]; 58 }; 59 60 static struct ltc4151_data *ltc4151_update_device(struct device *dev) 61 { 62 struct ltc4151_data *data = dev_get_drvdata(dev); 63 struct i2c_client *client = data->client; 64 struct ltc4151_data *ret = data; 65 66 mutex_lock(&data->update_lock); 67 68 /* 69 * The chip's A/D updates 6 times per second 70 * (Conversion Rate 6 - 9 Hz) 71 */ 72 if (time_after(jiffies, data->last_updated + HZ / 6) || !data->valid) { 73 int i; 74 75 dev_dbg(&client->dev, "Starting ltc4151 update\n"); 76 77 /* Read all registers */ 78 for (i = 0; i < ARRAY_SIZE(data->regs); i++) { 79 int val; 80 81 val = i2c_smbus_read_byte_data(client, i); 82 if (unlikely(val < 0)) { 83 dev_dbg(dev, 84 "Failed to read ADC value: error %d\n", 85 val); 86 ret = ERR_PTR(val); 87 goto abort; 88 } 89 data->regs[i] = val; 90 } 91 data->last_updated = jiffies; 92 data->valid = 1; 93 } 94 abort: 95 mutex_unlock(&data->update_lock); 96 return ret; 97 } 98 99 /* Return the voltage from the given register in mV */ 100 static int ltc4151_get_value(struct ltc4151_data *data, u8 reg) 101 { 102 u32 val; 103 104 val = (data->regs[reg] << 4) + (data->regs[reg + 1] >> 4); 105 106 switch (reg) { 107 case LTC4151_ADIN_H: 108 /* 500uV resolution. Convert to mV. */ 109 val = val * 500 / 1000; 110 break; 111 case LTC4151_SENSE_H: 112 /* 113 * 20uV resolution. Convert to current as measured with 114 * an 1 mOhm sense resistor, in mA. 115 */ 116 val = val * 20; 117 break; 118 case LTC4151_VIN_H: 119 /* 25 mV per increment */ 120 val = val * 25; 121 break; 122 default: 123 /* If we get here, the developer messed up */ 124 WARN_ON_ONCE(1); 125 val = 0; 126 break; 127 } 128 129 return val; 130 } 131 132 static ssize_t ltc4151_show_value(struct device *dev, 133 struct device_attribute *da, char *buf) 134 { 135 struct sensor_device_attribute *attr = to_sensor_dev_attr(da); 136 struct ltc4151_data *data = ltc4151_update_device(dev); 137 int value; 138 139 if (IS_ERR(data)) 140 return PTR_ERR(data); 141 142 value = ltc4151_get_value(data, attr->index); 143 return snprintf(buf, PAGE_SIZE, "%d\n", value); 144 } 145 146 /* 147 * Input voltages. 148 */ 149 static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, ltc4151_show_value, NULL, 150 LTC4151_VIN_H); 151 static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, ltc4151_show_value, NULL, 152 LTC4151_ADIN_H); 153 154 /* Currents (via sense resistor) */ 155 static SENSOR_DEVICE_ATTR(curr1_input, S_IRUGO, ltc4151_show_value, NULL, 156 LTC4151_SENSE_H); 157 158 /* 159 * Finally, construct an array of pointers to members of the above objects, 160 * as required for sysfs_create_group() 161 */ 162 static struct attribute *ltc4151_attrs[] = { 163 &sensor_dev_attr_in1_input.dev_attr.attr, 164 &sensor_dev_attr_in2_input.dev_attr.attr, 165 166 &sensor_dev_attr_curr1_input.dev_attr.attr, 167 168 NULL, 169 }; 170 ATTRIBUTE_GROUPS(ltc4151); 171 172 static int ltc4151_probe(struct i2c_client *client, 173 const struct i2c_device_id *id) 174 { 175 struct i2c_adapter *adapter = client->adapter; 176 struct device *dev = &client->dev; 177 struct ltc4151_data *data; 178 struct device *hwmon_dev; 179 180 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)) 181 return -ENODEV; 182 183 data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL); 184 if (!data) 185 return -ENOMEM; 186 187 data->client = client; 188 mutex_init(&data->update_lock); 189 190 hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name, 191 data, 192 ltc4151_groups); 193 return PTR_ERR_OR_ZERO(hwmon_dev); 194 } 195 196 static const struct i2c_device_id ltc4151_id[] = { 197 { "ltc4151", 0 }, 198 { } 199 }; 200 MODULE_DEVICE_TABLE(i2c, ltc4151_id); 201 202 /* This is the driver that will be inserted */ 203 static struct i2c_driver ltc4151_driver = { 204 .driver = { 205 .name = "ltc4151", 206 }, 207 .probe = ltc4151_probe, 208 .id_table = ltc4151_id, 209 }; 210 211 module_i2c_driver(ltc4151_driver); 212 213 MODULE_AUTHOR("Per Dalen <per.dalen@appeartv.com>"); 214 MODULE_DESCRIPTION("LTC4151 driver"); 215 MODULE_LICENSE("GPL"); 216