drivers/hwmon/ltc4261.c

   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                                 data->valid = 0;
  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 or mA */
 102 static int ltc4261_get_value(struct ltc4261_data *data, u8 reg)
 103 {
 104         u32 val;
 105
 106         val = (data->regs[reg] << 2) + (data->regs[reg + 1] >> 6);
 107
 108         switch (reg) {
 109         case LTC4261_ADIN_H:
 110         case LTC4261_ADIN2_H:
 111                 /* 2.5mV resolution. Convert to mV. */
 112                 val = val * 25 / 10;
 113                 break;
 114         case LTC4261_SENSE_H:
 115                 /*
 116                  * 62.5uV resolution. Convert to current as measured with
 117                  * an 1 mOhm sense resistor, in mA. If a different sense
 118                  * resistor is installed, calculate the actual current by
 119                  * dividing the reported current by the sense resistor value
 120                  * in mOhm.
 121                  */
 122                 val = val * 625 / 10;
 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 ltc4261_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 ltc4261_data *data = ltc4261_update_device(dev);
 139         int value;
 140
 141         if (IS_ERR(data))
 142                 return PTR_ERR(data);
 143
 144         value = ltc4261_get_value(data, attr->index);
 145         return snprintf(buf, PAGE_SIZE, "%d\n", value);
 146 }
 147
 148 static ssize_t ltc4261_show_bool(struct device *dev,
 149                                  struct device_attribute *da, char *buf)
 150 {
 151         struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
 152         struct i2c_client *client = to_i2c_client(dev);
 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(client, LTC4261_FAULT, ~fault);
 162
 163         return snprintf(buf, PAGE_SIZE, "%d\n", fault ? 1 : 0);
 164 }
 165
 166 /*
 167  * These macros are used below in constructing device attribute objects
 168  * for use with sysfs_create_group() to make a sysfs device file
 169  * for each register.
 170  */
 171
 172 #define LTC4261_VALUE(name, ltc4261_cmd_idx) \
 173         static SENSOR_DEVICE_ATTR(name, S_IRUGO, \
 174         ltc4261_show_value, NULL, ltc4261_cmd_idx)
 175
 176 #define LTC4261_BOOL(name, mask) \
 177         static SENSOR_DEVICE_ATTR(name, S_IRUGO, \
 178         ltc4261_show_bool, NULL, (mask))
 179
 180 /*
 181  * Input voltages.
 182  */
 183 LTC4261_VALUE(in1_input, LTC4261_ADIN_H);
 184 LTC4261_VALUE(in2_input, LTC4261_ADIN2_H);
 185
 186 /*
 187  * Voltage alarms. The chip has only one set of voltage alarm status bits,
 188  * triggered by input voltage alarms. In many designs, those alarms are
 189  * associated with the ADIN2 sensor, due to the proximity of the ADIN2 pin
 190  * to the OV pin. ADIN2 is, however, not available on all chip variants.
 191  * To ensure that the alarm condition is reported to the user, report it
 192  * with both voltage sensors.
 193  */
 194 LTC4261_BOOL(in1_min_alarm, FAULT_UV);
 195 LTC4261_BOOL(in1_max_alarm, FAULT_OV);
 196 LTC4261_BOOL(in2_min_alarm, FAULT_UV);
 197 LTC4261_BOOL(in2_max_alarm, FAULT_OV);
 198
 199 /* Currents (via sense resistor) */
 200 LTC4261_VALUE(curr1_input, LTC4261_SENSE_H);
 201
 202 /* Overcurrent alarm */
 203 LTC4261_BOOL(curr1_max_alarm, FAULT_OC);
 204
 205 static struct attribute *ltc4261_attributes[] = {
 206         &sensor_dev_attr_in1_input.dev_attr.attr,
 207         &sensor_dev_attr_in1_min_alarm.dev_attr.attr,
 208         &sensor_dev_attr_in1_max_alarm.dev_attr.attr,
 209         &sensor_dev_attr_in2_input.dev_attr.attr,
 210         &sensor_dev_attr_in2_min_alarm.dev_attr.attr,
 211         &sensor_dev_attr_in2_max_alarm.dev_attr.attr,
 212
 213         &sensor_dev_attr_curr1_input.dev_attr.attr,
 214         &sensor_dev_attr_curr1_max_alarm.dev_attr.attr,
 215
 216         NULL,
 217 };
 218
 219 static const struct attribute_group ltc4261_group = {
 220         .attrs = ltc4261_attributes,
 221 };
 222
 223 static int ltc4261_probe(struct i2c_client *client,
 224                          const struct i2c_device_id *id)
 225 {
 226         struct i2c_adapter *adapter = client->adapter;
 227         struct ltc4261_data *data;
 228         int ret;
 229
 230         if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
 231                 return -ENODEV;
 232
 233         if (i2c_smbus_read_byte_data(client, LTC4261_STATUS) < 0) {
 234                 dev_err(&client->dev, "Failed to read status register\n");
 235                 return -ENODEV;
 236         }
 237
 238         data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL);
 239         if (!data)
 240                 return -ENOMEM;
 241
 242         i2c_set_clientdata(client, data);
 243         mutex_init(&data->update_lock);
 244
 245         /* Clear faults */
 246         i2c_smbus_write_byte_data(client, LTC4261_FAULT, 0x00);
 247
 248         /* Register sysfs hooks */
 249         ret = sysfs_create_group(&client->dev.kobj, &ltc4261_group);
 250         if (ret)
 251                 return ret;
 252
 253         data->hwmon_dev = hwmon_device_register(&client->dev);
 254         if (IS_ERR(data->hwmon_dev)) {
 255                 ret = PTR_ERR(data->hwmon_dev);
 256                 goto out_hwmon_device_register;
 257         }
 258
 259         return 0;
 260
 261 out_hwmon_device_register:
 262         sysfs_remove_group(&client->dev.kobj, &ltc4261_group);
 263         return ret;
 264 }
 265
 266 static int ltc4261_remove(struct i2c_client *client)
 267 {
 268         struct ltc4261_data *data = i2c_get_clientdata(client);
 269
 270         hwmon_device_unregister(data->hwmon_dev);
 271         sysfs_remove_group(&client->dev.kobj, &ltc4261_group);
 272
 273         return 0;
 274 }
 275
 276 static const struct i2c_device_id ltc4261_id[] = {
 277         {"ltc4261", 0},
 278         {}
 279 };
 280
 281 MODULE_DEVICE_TABLE(i2c, ltc4261_id);
 282
 283 /* This is the driver that will be inserted */
 284 static struct i2c_driver ltc4261_driver = {
 285         .driver = {
 286                    .name = "ltc4261",
 287                    },
 288         .probe = ltc4261_probe,
 289         .remove = ltc4261_remove,
 290         .id_table = ltc4261_id,
 291 };
 292
 293 module_i2c_driver(ltc4261_driver);
 294
 295 MODULE_AUTHOR("Guenter Roeck <guenter.roeck@ericsson.com>");
 296 MODULE_DESCRIPTION("LTC4261 driver");
 297 MODULE_LICENSE("GPL");