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 40 /* chip registers */ 41 #define LTC4151_SENSE_H 0x00 42 #define LTC4151_SENSE_L 0x01 43 #define LTC4151_VIN_H 0x02 44 #define LTC4151_VIN_L 0x03 45 #define LTC4151_ADIN_H 0x04 46 #define LTC4151_ADIN_L 0x05 47 48 struct ltc4151_data { 49 struct device *hwmon_dev; 50 51 struct mutex update_lock; 52 bool valid; 53 unsigned long last_updated; /* in jiffies */ 54 55 /* Registers */ 56 u8 regs[6]; 57 }; 58 59 static struct ltc4151_data *ltc4151_update_device(struct device *dev) 60 { 61 struct i2c_client *client = to_i2c_client(dev); 62 struct ltc4151_data *data = i2c_get_clientdata(client); 63 struct ltc4151_data *ret = data; 64 65 mutex_lock(&data->update_lock); 66 67 /* 68 * The chip's A/D updates 6 times per second 69 * (Conversion Rate 6 - 9 Hz) 70 */ 71 if (time_after(jiffies, data->last_updated + HZ / 6) || !data->valid) { 72 int i; 73 74 dev_dbg(&client->dev, "Starting ltc4151 update\n"); 75 76 /* Read all registers */ 77 for (i = 0; i < ARRAY_SIZE(data->regs); i++) { 78 int val; 79 80 val = i2c_smbus_read_byte_data(client, i); 81 if (unlikely(val < 0)) { 82 dev_dbg(dev, 83 "Failed to read ADC value: error %d\n", 84 val); 85 ret = ERR_PTR(val); 86 goto abort; 87 } 88 data->regs[i] = val; 89 } 90 data->last_updated = jiffies; 91 data->valid = 1; 92 } 93 abort: 94 mutex_unlock(&data->update_lock); 95 return ret; 96 } 97 98 /* Return the voltage from the given register in mV */ 99 static int ltc4151_get_value(struct ltc4151_data *data, u8 reg) 100 { 101 u32 val; 102 103 val = (data->regs[reg] << 4) + (data->regs[reg + 1] >> 4); 104 105 switch (reg) { 106 case LTC4151_ADIN_H: 107 /* 500uV resolution. Convert to mV. */ 108 val = val * 500 / 1000; 109 break; 110 case LTC4151_SENSE_H: 111 /* 112 * 20uV resolution. Convert to current as measured with 113 * an 1 mOhm sense resistor, in mA. 114 */ 115 val = val * 20; 116 break; 117 case LTC4151_VIN_H: 118 /* 25 mV per increment */ 119 val = val * 25; 120 break; 121 default: 122 /* If we get here, the developer messed up */ 123 WARN_ON_ONCE(1); 124 val = 0; 125 break; 126 } 127 128 return val; 129 } 130 131 static ssize_t ltc4151_show_value(struct device *dev, 132 struct device_attribute *da, char *buf) 133 { 134 struct sensor_device_attribute *attr = to_sensor_dev_attr(da); 135 struct ltc4151_data *data = ltc4151_update_device(dev); 136 int value; 137 138 if (IS_ERR(data)) 139 return PTR_ERR(data); 140 141 value = ltc4151_get_value(data, attr->index); 142 return snprintf(buf, PAGE_SIZE, "%d\n", value); 143 } 144 145 /* 146 * Input voltages. 147 */ 148 static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, \ 149 ltc4151_show_value, NULL, LTC4151_VIN_H); 150 static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, \ 151 ltc4151_show_value, NULL, LTC4151_ADIN_H); 152 153 /* Currents (via sense resistor) */ 154 static SENSOR_DEVICE_ATTR(curr1_input, S_IRUGO, \ 155 ltc4151_show_value, NULL, LTC4151_SENSE_H); 156 157 /* 158 * Finally, construct an array of pointers to members of the above objects, 159 * as required for sysfs_create_group() 160 */ 161 static struct attribute *ltc4151_attributes[] = { 162 &sensor_dev_attr_in1_input.dev_attr.attr, 163 &sensor_dev_attr_in2_input.dev_attr.attr, 164 165 &sensor_dev_attr_curr1_input.dev_attr.attr, 166 167 NULL, 168 }; 169 170 static const struct attribute_group ltc4151_group = { 171 .attrs = ltc4151_attributes, 172 }; 173 174 static int ltc4151_probe(struct i2c_client *client, 175 const struct i2c_device_id *id) 176 { 177 struct i2c_adapter *adapter = client->adapter; 178 struct ltc4151_data *data; 179 int ret; 180 181 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)) 182 return -ENODEV; 183 184 data = kzalloc(sizeof(*data), GFP_KERNEL); 185 if (!data) { 186 ret = -ENOMEM; 187 goto out_kzalloc; 188 } 189 190 i2c_set_clientdata(client, data); 191 mutex_init(&data->update_lock); 192 193 /* Register sysfs hooks */ 194 ret = sysfs_create_group(&client->dev.kobj, <c4151_group); 195 if (ret) 196 goto out_sysfs_create_group; 197 198 data->hwmon_dev = hwmon_device_register(&client->dev); 199 if (IS_ERR(data->hwmon_dev)) { 200 ret = PTR_ERR(data->hwmon_dev); 201 goto out_hwmon_device_register; 202 } 203 204 return 0; 205 206 out_hwmon_device_register: 207 sysfs_remove_group(&client->dev.kobj, <c4151_group); 208 out_sysfs_create_group: 209 kfree(data); 210 out_kzalloc: 211 return ret; 212 } 213 214 static int ltc4151_remove(struct i2c_client *client) 215 { 216 struct ltc4151_data *data = i2c_get_clientdata(client); 217 218 hwmon_device_unregister(data->hwmon_dev); 219 sysfs_remove_group(&client->dev.kobj, <c4151_group); 220 221 kfree(data); 222 223 return 0; 224 } 225 226 static const struct i2c_device_id ltc4151_id[] = { 227 { "ltc4151", 0 }, 228 { } 229 }; 230 MODULE_DEVICE_TABLE(i2c, ltc4151_id); 231 232 /* This is the driver that will be inserted */ 233 static struct i2c_driver ltc4151_driver = { 234 .driver = { 235 .name = "ltc4151", 236 }, 237 .probe = ltc4151_probe, 238 .remove = ltc4151_remove, 239 .id_table = ltc4151_id, 240 }; 241 242 module_i2c_driver(ltc4151_driver); 243 244 MODULE_AUTHOR("Per Dalen <per.dalen@appeartv.com>"); 245 MODULE_DESCRIPTION("LTC4151 driver"); 246 MODULE_LICENSE("GPL"); 247