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/of.h> 34 #include <linux/init.h> 35 #include <linux/err.h> 36 #include <linux/slab.h> 37 #include <linux/i2c.h> 38 #include <linux/hwmon.h> 39 #include <linux/hwmon-sysfs.h> 40 #include <linux/jiffies.h> 41 42 /* chip registers */ 43 #define LTC4151_SENSE_H 0x00 44 #define LTC4151_SENSE_L 0x01 45 #define LTC4151_VIN_H 0x02 46 #define LTC4151_VIN_L 0x03 47 #define LTC4151_ADIN_H 0x04 48 #define LTC4151_ADIN_L 0x05 49 50 struct ltc4151_data { 51 struct i2c_client *client; 52 53 struct mutex update_lock; 54 bool valid; 55 unsigned long last_updated; /* in jiffies */ 56 unsigned int shunt; /* in micro ohms */ 57 58 /* Registers */ 59 u8 regs[6]; 60 }; 61 62 static struct ltc4151_data *ltc4151_update_device(struct device *dev) 63 { 64 struct ltc4151_data *data = dev_get_drvdata(dev); 65 struct i2c_client *client = data->client; 66 struct ltc4151_data *ret = data; 67 68 mutex_lock(&data->update_lock); 69 70 /* 71 * The chip's A/D updates 6 times per second 72 * (Conversion Rate 6 - 9 Hz) 73 */ 74 if (time_after(jiffies, data->last_updated + HZ / 6) || !data->valid) { 75 int i; 76 77 dev_dbg(&client->dev, "Starting ltc4151 update\n"); 78 79 /* Read all registers */ 80 for (i = 0; i < ARRAY_SIZE(data->regs); i++) { 81 int val; 82 83 val = i2c_smbus_read_byte_data(client, i); 84 if (unlikely(val < 0)) { 85 dev_dbg(dev, 86 "Failed to read ADC value: error %d\n", 87 val); 88 ret = ERR_PTR(val); 89 goto abort; 90 } 91 data->regs[i] = val; 92 } 93 data->last_updated = jiffies; 94 data->valid = 1; 95 } 96 abort: 97 mutex_unlock(&data->update_lock); 98 return ret; 99 } 100 101 /* Return the voltage from the given register in mV */ 102 static int ltc4151_get_value(struct ltc4151_data *data, u8 reg) 103 { 104 u32 val; 105 106 val = (data->regs[reg] << 4) + (data->regs[reg + 1] >> 4); 107 108 switch (reg) { 109 case LTC4151_ADIN_H: 110 /* 500uV resolution. Convert to mV. */ 111 val = val * 500 / 1000; 112 break; 113 case LTC4151_SENSE_H: 114 /* 115 * 20uV resolution. Convert to current as measured with 116 * a given sense resistor, in mA. 117 */ 118 val = val * 20 * 1000 / data->shunt; 119 break; 120 case LTC4151_VIN_H: 121 /* 25 mV per increment */ 122 val = val * 25; 123 break; 124 default: 125 /* If we get here, the developer messed up */ 126 WARN_ON_ONCE(1); 127 val = 0; 128 break; 129 } 130 131 return val; 132 } 133 134 static ssize_t ltc4151_show_value(struct device *dev, 135 struct device_attribute *da, char *buf) 136 { 137 struct sensor_device_attribute *attr = to_sensor_dev_attr(da); 138 struct ltc4151_data *data = ltc4151_update_device(dev); 139 int value; 140 141 if (IS_ERR(data)) 142 return PTR_ERR(data); 143 144 value = ltc4151_get_value(data, attr->index); 145 return snprintf(buf, PAGE_SIZE, "%d\n", value); 146 } 147 148 /* 149 * Input voltages. 150 */ 151 static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, ltc4151_show_value, NULL, 152 LTC4151_VIN_H); 153 static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, ltc4151_show_value, NULL, 154 LTC4151_ADIN_H); 155 156 /* Currents (via sense resistor) */ 157 static SENSOR_DEVICE_ATTR(curr1_input, S_IRUGO, ltc4151_show_value, NULL, 158 LTC4151_SENSE_H); 159 160 /* 161 * Finally, construct an array of pointers to members of the above objects, 162 * as required for sysfs_create_group() 163 */ 164 static struct attribute *ltc4151_attrs[] = { 165 &sensor_dev_attr_in1_input.dev_attr.attr, 166 &sensor_dev_attr_in2_input.dev_attr.attr, 167 168 &sensor_dev_attr_curr1_input.dev_attr.attr, 169 170 NULL, 171 }; 172 ATTRIBUTE_GROUPS(ltc4151); 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 device *dev = &client->dev; 179 struct ltc4151_data *data; 180 struct device *hwmon_dev; 181 u32 shunt; 182 183 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)) 184 return -ENODEV; 185 186 data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL); 187 if (!data) 188 return -ENOMEM; 189 190 if (of_property_read_u32(client->dev.of_node, 191 "shunt-resistor-micro-ohms", &shunt)) 192 shunt = 1000; /* 1 mOhm if not set via DT */ 193 194 if (shunt == 0) 195 return -EINVAL; 196 197 data->shunt = shunt; 198 199 data->client = client; 200 mutex_init(&data->update_lock); 201 202 hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name, 203 data, 204 ltc4151_groups); 205 return PTR_ERR_OR_ZERO(hwmon_dev); 206 } 207 208 static const struct i2c_device_id ltc4151_id[] = { 209 { "ltc4151", 0 }, 210 { } 211 }; 212 MODULE_DEVICE_TABLE(i2c, ltc4151_id); 213 214 static const struct of_device_id ltc4151_match[] = { 215 { .compatible = "lltc,ltc4151" }, 216 {}, 217 }; 218 219 /* This is the driver that will be inserted */ 220 static struct i2c_driver ltc4151_driver = { 221 .driver = { 222 .name = "ltc4151", 223 .of_match_table = of_match_ptr(ltc4151_match), 224 }, 225 .probe = ltc4151_probe, 226 .id_table = ltc4151_id, 227 }; 228 229 module_i2c_driver(ltc4151_driver); 230 231 MODULE_AUTHOR("Per Dalen <per.dalen@appeartv.com>"); 232 MODULE_DESCRIPTION("LTC4151 driver"); 233 MODULE_LICENSE("GPL"); 234