1 /* 2 * Driver for Linear Technology LTC4261 I2C Negative Voltage Hot Swap Controller 3 * 4 * Copyright (C) 2010 Ericsson AB. 5 * 6 * Derived from: 7 * 8 * Driver for Linear Technology LTC4245 I2C Multiple Supply Hot Swap Controller 9 * Copyright (C) 2008 Ira W. Snyder <iws@ovro.caltech.edu> 10 * 11 * Datasheet: http://cds.linear.com/docs/Datasheet/42612fb.pdf 12 * 13 * This program is free software; you can redistribute it and/or modify 14 * it under the terms of the GNU General Public License as published by 15 * the Free Software Foundation; either version 2 of the License, or 16 * (at your option) any later version. 17 * 18 * This program is distributed in the hope that it will be useful, 19 * but WITHOUT ANY WARRANTY; without even the implied warranty of 20 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 21 * GNU General Public License for more details. 22 * 23 * You should have received a copy of the GNU General Public License 24 * along with this program; if not, write to the Free Software 25 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 26 */ 27 28 #include <linux/kernel.h> 29 #include <linux/module.h> 30 #include <linux/init.h> 31 #include <linux/err.h> 32 #include <linux/slab.h> 33 #include <linux/i2c.h> 34 #include <linux/hwmon.h> 35 #include <linux/hwmon-sysfs.h> 36 #include <linux/jiffies.h> 37 38 /* chip registers */ 39 #define LTC4261_STATUS 0x00 /* readonly */ 40 #define LTC4261_FAULT 0x01 41 #define LTC4261_ALERT 0x02 42 #define LTC4261_CONTROL 0x03 43 #define LTC4261_SENSE_H 0x04 44 #define LTC4261_SENSE_L 0x05 45 #define LTC4261_ADIN2_H 0x06 46 #define LTC4261_ADIN2_L 0x07 47 #define LTC4261_ADIN_H 0x08 48 #define LTC4261_ADIN_L 0x09 49 50 /* 51 * Fault register bits 52 */ 53 #define FAULT_OV (1<<0) 54 #define FAULT_UV (1<<1) 55 #define FAULT_OC (1<<2) 56 57 struct ltc4261_data { 58 struct i2c_client *client; 59 60 struct mutex update_lock; 61 bool valid; 62 unsigned long last_updated; /* in jiffies */ 63 64 /* Registers */ 65 u8 regs[10]; 66 }; 67 68 static struct ltc4261_data *ltc4261_update_device(struct device *dev) 69 { 70 struct ltc4261_data *data = dev_get_drvdata(dev); 71 struct i2c_client *client = data->client; 72 struct ltc4261_data *ret = data; 73 74 mutex_lock(&data->update_lock); 75 76 if (time_after(jiffies, data->last_updated + HZ / 4) || !data->valid) { 77 int i; 78 79 /* Read registers -- 0x00 to 0x09 */ 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 data->valid = 0; 90 goto abort; 91 } 92 data->regs[i] = val; 93 } 94 data->last_updated = jiffies; 95 data->valid = 1; 96 } 97 abort: 98 mutex_unlock(&data->update_lock); 99 return ret; 100 } 101 102 /* Return the voltage from the given register in mV or mA */ 103 static int ltc4261_get_value(struct ltc4261_data *data, u8 reg) 104 { 105 u32 val; 106 107 val = (data->regs[reg] << 2) + (data->regs[reg + 1] >> 6); 108 109 switch (reg) { 110 case LTC4261_ADIN_H: 111 case LTC4261_ADIN2_H: 112 /* 2.5mV resolution. Convert to mV. */ 113 val = val * 25 / 10; 114 break; 115 case LTC4261_SENSE_H: 116 /* 117 * 62.5uV resolution. Convert to current as measured with 118 * an 1 mOhm sense resistor, in mA. If a different sense 119 * resistor is installed, calculate the actual current by 120 * dividing the reported current by the sense resistor value 121 * in mOhm. 122 */ 123 val = val * 625 / 10; 124 break; 125 default: 126 /* If we get here, the developer messed up */ 127 WARN_ON_ONCE(1); 128 val = 0; 129 break; 130 } 131 132 return val; 133 } 134 135 static ssize_t ltc4261_show_value(struct device *dev, 136 struct device_attribute *da, char *buf) 137 { 138 struct sensor_device_attribute *attr = to_sensor_dev_attr(da); 139 struct ltc4261_data *data = ltc4261_update_device(dev); 140 int value; 141 142 if (IS_ERR(data)) 143 return PTR_ERR(data); 144 145 value = ltc4261_get_value(data, attr->index); 146 return snprintf(buf, PAGE_SIZE, "%d\n", value); 147 } 148 149 static ssize_t ltc4261_show_bool(struct device *dev, 150 struct device_attribute *da, char *buf) 151 { 152 struct sensor_device_attribute *attr = to_sensor_dev_attr(da); 153 struct ltc4261_data *data = ltc4261_update_device(dev); 154 u8 fault; 155 156 if (IS_ERR(data)) 157 return PTR_ERR(data); 158 159 fault = data->regs[LTC4261_FAULT] & attr->index; 160 if (fault) /* Clear reported faults in chip register */ 161 i2c_smbus_write_byte_data(data->client, LTC4261_FAULT, ~fault); 162 163 return snprintf(buf, PAGE_SIZE, "%d\n", fault ? 1 : 0); 164 } 165 166 /* 167 * Input voltages. 168 */ 169 static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, ltc4261_show_value, NULL, 170 LTC4261_ADIN_H); 171 static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, ltc4261_show_value, NULL, 172 LTC4261_ADIN2_H); 173 174 /* 175 * Voltage alarms. The chip has only one set of voltage alarm status bits, 176 * triggered by input voltage alarms. In many designs, those alarms are 177 * associated with the ADIN2 sensor, due to the proximity of the ADIN2 pin 178 * to the OV pin. ADIN2 is, however, not available on all chip variants. 179 * To ensure that the alarm condition is reported to the user, report it 180 * with both voltage sensors. 181 */ 182 static SENSOR_DEVICE_ATTR(in1_min_alarm, S_IRUGO, ltc4261_show_bool, NULL, 183 FAULT_UV); 184 static SENSOR_DEVICE_ATTR(in1_max_alarm, S_IRUGO, ltc4261_show_bool, NULL, 185 FAULT_OV); 186 static SENSOR_DEVICE_ATTR(in2_min_alarm, S_IRUGO, ltc4261_show_bool, NULL, 187 FAULT_UV); 188 static SENSOR_DEVICE_ATTR(in2_max_alarm, S_IRUGO, ltc4261_show_bool, NULL, 189 FAULT_OV); 190 191 /* Currents (via sense resistor) */ 192 static SENSOR_DEVICE_ATTR(curr1_input, S_IRUGO, ltc4261_show_value, NULL, 193 LTC4261_SENSE_H); 194 195 /* Overcurrent alarm */ 196 static SENSOR_DEVICE_ATTR(curr1_max_alarm, S_IRUGO, ltc4261_show_bool, NULL, 197 FAULT_OC); 198 199 static struct attribute *ltc4261_attrs[] = { 200 &sensor_dev_attr_in1_input.dev_attr.attr, 201 &sensor_dev_attr_in1_min_alarm.dev_attr.attr, 202 &sensor_dev_attr_in1_max_alarm.dev_attr.attr, 203 &sensor_dev_attr_in2_input.dev_attr.attr, 204 &sensor_dev_attr_in2_min_alarm.dev_attr.attr, 205 &sensor_dev_attr_in2_max_alarm.dev_attr.attr, 206 207 &sensor_dev_attr_curr1_input.dev_attr.attr, 208 &sensor_dev_attr_curr1_max_alarm.dev_attr.attr, 209 210 NULL, 211 }; 212 ATTRIBUTE_GROUPS(ltc4261); 213 214 static int ltc4261_probe(struct i2c_client *client, 215 const struct i2c_device_id *id) 216 { 217 struct i2c_adapter *adapter = client->adapter; 218 struct device *dev = &client->dev; 219 struct ltc4261_data *data; 220 struct device *hwmon_dev; 221 222 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)) 223 return -ENODEV; 224 225 if (i2c_smbus_read_byte_data(client, LTC4261_STATUS) < 0) { 226 dev_err(dev, "Failed to read status register\n"); 227 return -ENODEV; 228 } 229 230 data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL); 231 if (!data) 232 return -ENOMEM; 233 234 data->client = client; 235 mutex_init(&data->update_lock); 236 237 /* Clear faults */ 238 i2c_smbus_write_byte_data(client, LTC4261_FAULT, 0x00); 239 240 hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name, 241 data, 242 ltc4261_groups); 243 return PTR_ERR_OR_ZERO(hwmon_dev); 244 } 245 246 static const struct i2c_device_id ltc4261_id[] = { 247 {"ltc4261", 0}, 248 {} 249 }; 250 251 MODULE_DEVICE_TABLE(i2c, ltc4261_id); 252 253 /* This is the driver that will be inserted */ 254 static struct i2c_driver ltc4261_driver = { 255 .driver = { 256 .name = "ltc4261", 257 }, 258 .probe = ltc4261_probe, 259 .id_table = ltc4261_id, 260 }; 261 262 module_i2c_driver(ltc4261_driver); 263 264 MODULE_AUTHOR("Guenter Roeck <linux@roeck-us.net>"); 265 MODULE_DESCRIPTION("LTC4261 driver"); 266 MODULE_LICENSE("GPL"); 267