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 37 /* chip registers */ 38 #define LTC4261_STATUS 0x00 /* readonly */ 39 #define LTC4261_FAULT 0x01 40 #define LTC4261_ALERT 0x02 41 #define LTC4261_CONTROL 0x03 42 #define LTC4261_SENSE_H 0x04 43 #define LTC4261_SENSE_L 0x05 44 #define LTC4261_ADIN2_H 0x06 45 #define LTC4261_ADIN2_L 0x07 46 #define LTC4261_ADIN_H 0x08 47 #define LTC4261_ADIN_L 0x09 48 49 /* 50 * Fault register bits 51 */ 52 #define FAULT_OV (1<<0) 53 #define FAULT_UV (1<<1) 54 #define FAULT_OC (1<<2) 55 56 struct ltc4261_data { 57 struct device *hwmon_dev; 58 59 struct mutex update_lock; 60 bool valid; 61 unsigned long last_updated; /* in jiffies */ 62 63 /* Registers */ 64 u8 regs[10]; 65 }; 66 67 static struct ltc4261_data *ltc4261_update_device(struct device *dev) 68 { 69 struct i2c_client *client = to_i2c_client(dev); 70 struct ltc4261_data *data = i2c_get_clientdata(client); 71 struct ltc4261_data *ret = data; 72 73 mutex_lock(&data->update_lock); 74 75 if (time_after(jiffies, data->last_updated + HZ / 4) || !data->valid) { 76 int i; 77 78 /* Read registers -- 0x00 to 0x09 */ 79 for (i = 0; i < ARRAY_SIZE(data->regs); i++) { 80 int val; 81 82 val = i2c_smbus_read_byte_data(client, i); 83 if (unlikely(val < 0)) { 84 dev_dbg(dev, 85 "Failed to read ADC value: error %d\n", 86 val); 87 ret = ERR_PTR(val); 88 goto abort; 89 } 90 data->regs[i] = val; 91 } 92 data->last_updated = jiffies; 93 data->valid = 1; 94 } 95 abort: 96 mutex_unlock(&data->update_lock); 97 return ret; 98 } 99 100 /* Return the voltage from the given register in mV or mA */ 101 static int ltc4261_get_value(struct ltc4261_data *data, u8 reg) 102 { 103 u32 val; 104 105 val = (data->regs[reg] << 2) + (data->regs[reg + 1] >> 6); 106 107 switch (reg) { 108 case LTC4261_ADIN_H: 109 case LTC4261_ADIN2_H: 110 /* 2.5mV resolution. Convert to mV. */ 111 val = val * 25 / 10; 112 break; 113 case LTC4261_SENSE_H: 114 /* 115 * 62.5uV resolution. Convert to current as measured with 116 * an 1 mOhm sense resistor, in mA. If a different sense 117 * resistor is installed, calculate the actual current by 118 * dividing the reported current by the sense resistor value 119 * in mOhm. 120 */ 121 val = val * 625 / 10; 122 break; 123 default: 124 /* If we get here, the developer messed up */ 125 WARN_ON_ONCE(1); 126 val = 0; 127 break; 128 } 129 130 return val; 131 } 132 133 static ssize_t ltc4261_show_value(struct device *dev, 134 struct device_attribute *da, char *buf) 135 { 136 struct sensor_device_attribute *attr = to_sensor_dev_attr(da); 137 struct ltc4261_data *data = ltc4261_update_device(dev); 138 int value; 139 140 if (IS_ERR(data)) 141 return PTR_ERR(data); 142 143 value = ltc4261_get_value(data, attr->index); 144 return snprintf(buf, PAGE_SIZE, "%d\n", value); 145 } 146 147 static ssize_t ltc4261_show_bool(struct device *dev, 148 struct device_attribute *da, char *buf) 149 { 150 struct sensor_device_attribute *attr = to_sensor_dev_attr(da); 151 struct i2c_client *client = to_i2c_client(dev); 152 struct ltc4261_data *data = ltc4261_update_device(dev); 153 u8 fault; 154 155 if (IS_ERR(data)) 156 return PTR_ERR(data); 157 158 fault = data->regs[LTC4261_FAULT] & attr->index; 159 if (fault) /* Clear reported faults in chip register */ 160 i2c_smbus_write_byte_data(client, LTC4261_FAULT, ~fault); 161 162 return snprintf(buf, PAGE_SIZE, "%d\n", fault ? 1 : 0); 163 } 164 165 /* 166 * These macros are used below in constructing device attribute objects 167 * for use with sysfs_create_group() to make a sysfs device file 168 * for each register. 169 */ 170 171 #define LTC4261_VALUE(name, ltc4261_cmd_idx) \ 172 static SENSOR_DEVICE_ATTR(name, S_IRUGO, \ 173 ltc4261_show_value, NULL, ltc4261_cmd_idx) 174 175 #define LTC4261_BOOL(name, mask) \ 176 static SENSOR_DEVICE_ATTR(name, S_IRUGO, \ 177 ltc4261_show_bool, NULL, (mask)) 178 179 /* 180 * Input voltages. 181 */ 182 LTC4261_VALUE(in1_input, LTC4261_ADIN_H); 183 LTC4261_VALUE(in2_input, LTC4261_ADIN2_H); 184 185 /* 186 * Voltage alarms. The chip has only one set of voltage alarm status bits, 187 * triggered by input voltage alarms. In many designs, those alarms are 188 * associated with the ADIN2 sensor, due to the proximity of the ADIN2 pin 189 * to the OV pin. ADIN2 is, however, not available on all chip variants. 190 * To ensure that the alarm condition is reported to the user, report it 191 * with both voltage sensors. 192 */ 193 LTC4261_BOOL(in1_min_alarm, FAULT_UV); 194 LTC4261_BOOL(in1_max_alarm, FAULT_OV); 195 LTC4261_BOOL(in2_min_alarm, FAULT_UV); 196 LTC4261_BOOL(in2_max_alarm, FAULT_OV); 197 198 /* Currents (via sense resistor) */ 199 LTC4261_VALUE(curr1_input, LTC4261_SENSE_H); 200 201 /* Overcurrent alarm */ 202 LTC4261_BOOL(curr1_max_alarm, FAULT_OC); 203 204 static struct attribute *ltc4261_attributes[] = { 205 &sensor_dev_attr_in1_input.dev_attr.attr, 206 &sensor_dev_attr_in1_min_alarm.dev_attr.attr, 207 &sensor_dev_attr_in1_max_alarm.dev_attr.attr, 208 &sensor_dev_attr_in2_input.dev_attr.attr, 209 &sensor_dev_attr_in2_min_alarm.dev_attr.attr, 210 &sensor_dev_attr_in2_max_alarm.dev_attr.attr, 211 212 &sensor_dev_attr_curr1_input.dev_attr.attr, 213 &sensor_dev_attr_curr1_max_alarm.dev_attr.attr, 214 215 NULL, 216 }; 217 218 static const struct attribute_group ltc4261_group = { 219 .attrs = ltc4261_attributes, 220 }; 221 222 static int ltc4261_probe(struct i2c_client *client, 223 const struct i2c_device_id *id) 224 { 225 struct i2c_adapter *adapter = client->adapter; 226 struct ltc4261_data *data; 227 int ret; 228 229 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)) 230 return -ENODEV; 231 232 if (i2c_smbus_read_byte_data(client, LTC4261_STATUS) < 0) { 233 dev_err(&client->dev, "Failed to read status register\n"); 234 return -ENODEV; 235 } 236 237 data = kzalloc(sizeof(*data), GFP_KERNEL); 238 if (!data) { 239 ret = -ENOMEM; 240 goto out_kzalloc; 241 } 242 243 i2c_set_clientdata(client, data); 244 mutex_init(&data->update_lock); 245 246 /* Clear faults */ 247 i2c_smbus_write_byte_data(client, LTC4261_FAULT, 0x00); 248 249 /* Register sysfs hooks */ 250 ret = sysfs_create_group(&client->dev.kobj, <c4261_group); 251 if (ret) 252 goto out_sysfs_create_group; 253 254 data->hwmon_dev = hwmon_device_register(&client->dev); 255 if (IS_ERR(data->hwmon_dev)) { 256 ret = PTR_ERR(data->hwmon_dev); 257 goto out_hwmon_device_register; 258 } 259 260 return 0; 261 262 out_hwmon_device_register: 263 sysfs_remove_group(&client->dev.kobj, <c4261_group); 264 out_sysfs_create_group: 265 kfree(data); 266 out_kzalloc: 267 return ret; 268 } 269 270 static int ltc4261_remove(struct i2c_client *client) 271 { 272 struct ltc4261_data *data = i2c_get_clientdata(client); 273 274 hwmon_device_unregister(data->hwmon_dev); 275 sysfs_remove_group(&client->dev.kobj, <c4261_group); 276 277 kfree(data); 278 279 return 0; 280 } 281 282 static const struct i2c_device_id ltc4261_id[] = { 283 {"ltc4261", 0}, 284 {} 285 }; 286 287 MODULE_DEVICE_TABLE(i2c, ltc4261_id); 288 289 /* This is the driver that will be inserted */ 290 static struct i2c_driver ltc4261_driver = { 291 .driver = { 292 .name = "ltc4261", 293 }, 294 .probe = ltc4261_probe, 295 .remove = ltc4261_remove, 296 .id_table = ltc4261_id, 297 }; 298 299 static int __init ltc4261_init(void) 300 { 301 return i2c_add_driver(<c4261_driver); 302 } 303 304 static void __exit ltc4261_exit(void) 305 { 306 i2c_del_driver(<c4261_driver); 307 } 308 309 MODULE_AUTHOR("Guenter Roeck <guenter.roeck@ericsson.com>"); 310 MODULE_DESCRIPTION("LTC4261 driver"); 311 MODULE_LICENSE("GPL"); 312 313 module_init(ltc4261_init); 314 module_exit(ltc4261_exit); 315