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 #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 device *hwmon_dev;
  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 i2c_client *client = to_i2c_client(dev);
  71         struct ltc4261_data *data = i2c_get_clientdata(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 i2c_client *client = to_i2c_client(dev);
 154         struct ltc4261_data *data = ltc4261_update_device(dev);
 155         u8 fault;
 156
 157         if (IS_ERR(data))
 158                 return PTR_ERR(data);
 159
 160         fault = data->regs[LTC4261_FAULT] & attr->index;
 161         if (fault)              /* Clear reported faults in chip register */
 162                 i2c_smbus_write_byte_data(client, LTC4261_FAULT, ~fault);
 163
 164         return snprintf(buf, PAGE_SIZE, "%d\n", fault ? 1 : 0);
 165 }
 166
 167 /*
 168  * These macros are used below in constructing device attribute objects
 169  * for use with sysfs_create_group() to make a sysfs device file
 170  * for each register.
 171  */
 172
 173 #define LTC4261_VALUE(name, ltc4261_cmd_idx) \
 174         static SENSOR_DEVICE_ATTR(name, S_IRUGO, \
 175         ltc4261_show_value, NULL, ltc4261_cmd_idx)
 176
 177 #define LTC4261_BOOL(name, mask) \
 178         static SENSOR_DEVICE_ATTR(name, S_IRUGO, \
 179         ltc4261_show_bool, NULL, (mask))
 180
 181 /*
 182  * Input voltages.
 183  */
 184 LTC4261_VALUE(in1_input, LTC4261_ADIN_H);
 185 LTC4261_VALUE(in2_input, LTC4261_ADIN2_H);
 186
 187 /*
 188  * Voltage alarms. The chip has only one set of voltage alarm status bits,
 189  * triggered by input voltage alarms. In many designs, those alarms are
 190  * associated with the ADIN2 sensor, due to the proximity of the ADIN2 pin
 191  * to the OV pin. ADIN2 is, however, not available on all chip variants.
 192  * To ensure that the alarm condition is reported to the user, report it
 193  * with both voltage sensors.
 194  */
 195 LTC4261_BOOL(in1_min_alarm, FAULT_UV);
 196 LTC4261_BOOL(in1_max_alarm, FAULT_OV);
 197 LTC4261_BOOL(in2_min_alarm, FAULT_UV);
 198 LTC4261_BOOL(in2_max_alarm, FAULT_OV);
 199
 200 /* Currents (via sense resistor) */
 201 LTC4261_VALUE(curr1_input, LTC4261_SENSE_H);
 202
 203 /* Overcurrent alarm */
 204 LTC4261_BOOL(curr1_max_alarm, FAULT_OC);
 205
 206 static struct attribute *ltc4261_attributes[] = {
 207         &sensor_dev_attr_in1_input.dev_attr.attr,
 208         &sensor_dev_attr_in1_min_alarm.dev_attr.attr,
 209         &sensor_dev_attr_in1_max_alarm.dev_attr.attr,
 210         &sensor_dev_attr_in2_input.dev_attr.attr,
 211         &sensor_dev_attr_in2_min_alarm.dev_attr.attr,
 212         &sensor_dev_attr_in2_max_alarm.dev_attr.attr,
 213
 214         &sensor_dev_attr_curr1_input.dev_attr.attr,
 215         &sensor_dev_attr_curr1_max_alarm.dev_attr.attr,
 216
 217         NULL,
 218 };
 219
 220 static const struct attribute_group ltc4261_group = {
 221         .attrs = ltc4261_attributes,
 222 };
 223
 224 static int ltc4261_probe(struct i2c_client *client,
 225                          const struct i2c_device_id *id)
 226 {
 227         struct i2c_adapter *adapter = client->adapter;
 228         struct ltc4261_data *data;
 229         int ret;
 230
 231         if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
 232                 return -ENODEV;
 233
 234         if (i2c_smbus_read_byte_data(client, LTC4261_STATUS) < 0) {
 235                 dev_err(&client->dev, "Failed to read status register\n");
 236                 return -ENODEV;
 237         }
 238
 239         data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL);
 240         if (!data)
 241                 return -ENOMEM;
 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, &ltc4261_group);
 251         if (ret)
 252                 return ret;
 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, &ltc4261_group);
 264         return ret;
 265 }
 266
 267 static int ltc4261_remove(struct i2c_client *client)
 268 {
 269         struct ltc4261_data *data = i2c_get_clientdata(client);
 270
 271         hwmon_device_unregister(data->hwmon_dev);
 272         sysfs_remove_group(&client->dev.kobj, &ltc4261_group);
 273
 274         return 0;
 275 }
 276
 277 static const struct i2c_device_id ltc4261_id[] = {
 278         {"ltc4261", 0},
 279         {}
 280 };
 281
 282 MODULE_DEVICE_TABLE(i2c, ltc4261_id);
 283
 284 /* This is the driver that will be inserted */
 285 static struct i2c_driver ltc4261_driver = {
 286         .driver = {
 287                    .name = "ltc4261",
 288                    },
 289         .probe = ltc4261_probe,
 290         .remove = ltc4261_remove,
 291         .id_table = ltc4261_id,
 292 };
 293
 294 module_i2c_driver(ltc4261_driver);
 295
 296 MODULE_AUTHOR("Guenter Roeck <linux@roeck-us.net>");
 297 MODULE_DESCRIPTION("LTC4261 driver");
 298 MODULE_LICENSE("GPL");