drivers/hwmon/ltc4261.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Driver for Linear Technology LTC4261 I2C Negative Voltage Hot Swap Controller
   4  *
   5  * Copyright (C) 2010 Ericsson AB.
   6  *
   7  * Derived from:
   8  *
   9  *  Driver for Linear Technology LTC4245 I2C Multiple Supply Hot Swap Controller
  10  *  Copyright (C) 2008 Ira W. Snyder <iws@ovro.caltech.edu>
  11  *
  12  * Datasheet: http://cds.linear.com/docs/Datasheet/42612fb.pdf
  13  */
  14
  15 #include <linux/kernel.h>
  16 #include <linux/module.h>
  17 #include <linux/init.h>
  18 #include <linux/err.h>
  19 #include <linux/slab.h>
  20 #include <linux/i2c.h>
  21 #include <linux/hwmon.h>
  22 #include <linux/hwmon-sysfs.h>
  23 #include <linux/jiffies.h>
  24
  25 /* chip registers */
  26 #define LTC4261_STATUS  0x00    /* readonly */
  27 #define LTC4261_FAULT   0x01
  28 #define LTC4261_ALERT   0x02
  29 #define LTC4261_CONTROL 0x03
  30 #define LTC4261_SENSE_H 0x04
  31 #define LTC4261_SENSE_L 0x05
  32 #define LTC4261_ADIN2_H 0x06
  33 #define LTC4261_ADIN2_L 0x07
  34 #define LTC4261_ADIN_H  0x08
  35 #define LTC4261_ADIN_L  0x09
  36
  37 /*
  38  * Fault register bits
  39  */
  40 #define FAULT_OV        (1<<0)
  41 #define FAULT_UV        (1<<1)
  42 #define FAULT_OC        (1<<2)
  43
  44 struct ltc4261_data {
  45         struct i2c_client *client;
  46
  47         struct mutex update_lock;
  48         bool valid;
  49         unsigned long last_updated;     /* in jiffies */
  50
  51         /* Registers */
  52         u8 regs[10];
  53 };
  54
  55 static struct ltc4261_data *ltc4261_update_device(struct device *dev)
  56 {
  57         struct ltc4261_data *data = dev_get_drvdata(dev);
  58         struct i2c_client *client = data->client;
  59         struct ltc4261_data *ret = data;
  60
  61         mutex_lock(&data->update_lock);
  62
  63         if (time_after(jiffies, data->last_updated + HZ / 4) || !data->valid) {
  64                 int i;
  65
  66                 /* Read registers -- 0x00 to 0x09 */
  67                 for (i = 0; i < ARRAY_SIZE(data->regs); i++) {
  68                         int val;
  69
  70                         val = i2c_smbus_read_byte_data(client, i);
  71                         if (unlikely(val < 0)) {
  72                                 dev_dbg(dev,
  73                                         "Failed to read ADC value: error %d\n",
  74                                         val);
  75                                 ret = ERR_PTR(val);
  76                                 data->valid = 0;
  77                                 goto abort;
  78                         }
  79                         data->regs[i] = val;
  80                 }
  81                 data->last_updated = jiffies;
  82                 data->valid = 1;
  83         }
  84 abort:
  85         mutex_unlock(&data->update_lock);
  86         return ret;
  87 }
  88
  89 /* Return the voltage from the given register in mV or mA */
  90 static int ltc4261_get_value(struct ltc4261_data *data, u8 reg)
  91 {
  92         u32 val;
  93
  94         val = (data->regs[reg] << 2) + (data->regs[reg + 1] >> 6);
  95
  96         switch (reg) {
  97         case LTC4261_ADIN_H:
  98         case LTC4261_ADIN2_H:
  99                 /* 2.5mV resolution. Convert to mV. */
 100                 val = val * 25 / 10;
 101                 break;
 102         case LTC4261_SENSE_H:
 103                 /*
 104                  * 62.5uV resolution. Convert to current as measured with
 105                  * an 1 mOhm sense resistor, in mA. If a different sense
 106                  * resistor is installed, calculate the actual current by
 107                  * dividing the reported current by the sense resistor value
 108                  * in mOhm.
 109                  */
 110                 val = val * 625 / 10;
 111                 break;
 112         default:
 113                 /* If we get here, the developer messed up */
 114                 WARN_ON_ONCE(1);
 115                 val = 0;
 116                 break;
 117         }
 118
 119         return val;
 120 }
 121
 122 static ssize_t ltc4261_value_show(struct device *dev,
 123                                   struct device_attribute *da, char *buf)
 124 {
 125         struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
 126         struct ltc4261_data *data = ltc4261_update_device(dev);
 127         int value;
 128
 129         if (IS_ERR(data))
 130                 return PTR_ERR(data);
 131
 132         value = ltc4261_get_value(data, attr->index);
 133         return snprintf(buf, PAGE_SIZE, "%d\n", value);
 134 }
 135
 136 static ssize_t ltc4261_bool_show(struct device *dev,
 137                                  struct device_attribute *da, char *buf)
 138 {
 139         struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
 140         struct ltc4261_data *data = ltc4261_update_device(dev);
 141         u8 fault;
 142
 143         if (IS_ERR(data))
 144                 return PTR_ERR(data);
 145
 146         fault = data->regs[LTC4261_FAULT] & attr->index;
 147         if (fault)              /* Clear reported faults in chip register */
 148                 i2c_smbus_write_byte_data(data->client, LTC4261_FAULT, ~fault);
 149
 150         return snprintf(buf, PAGE_SIZE, "%d\n", fault ? 1 : 0);
 151 }
 152
 153 /*
 154  * Input voltages.
 155  */
 156 static SENSOR_DEVICE_ATTR_RO(in1_input, ltc4261_value, LTC4261_ADIN_H);
 157 static SENSOR_DEVICE_ATTR_RO(in2_input, ltc4261_value, LTC4261_ADIN2_H);
 158
 159 /*
 160  * Voltage alarms. The chip has only one set of voltage alarm status bits,
 161  * triggered by input voltage alarms. In many designs, those alarms are
 162  * associated with the ADIN2 sensor, due to the proximity of the ADIN2 pin
 163  * to the OV pin. ADIN2 is, however, not available on all chip variants.
 164  * To ensure that the alarm condition is reported to the user, report it
 165  * with both voltage sensors.
 166  */
 167 static SENSOR_DEVICE_ATTR_RO(in1_min_alarm, ltc4261_bool, FAULT_UV);
 168 static SENSOR_DEVICE_ATTR_RO(in1_max_alarm, ltc4261_bool, FAULT_OV);
 169 static SENSOR_DEVICE_ATTR_RO(in2_min_alarm, ltc4261_bool, FAULT_UV);
 170 static SENSOR_DEVICE_ATTR_RO(in2_max_alarm, ltc4261_bool, FAULT_OV);
 171
 172 /* Currents (via sense resistor) */
 173 static SENSOR_DEVICE_ATTR_RO(curr1_input, ltc4261_value, LTC4261_SENSE_H);
 174
 175 /* Overcurrent alarm */
 176 static SENSOR_DEVICE_ATTR_RO(curr1_max_alarm, ltc4261_bool, FAULT_OC);
 177
 178 static struct attribute *ltc4261_attrs[] = {
 179         &sensor_dev_attr_in1_input.dev_attr.attr,
 180         &sensor_dev_attr_in1_min_alarm.dev_attr.attr,
 181         &sensor_dev_attr_in1_max_alarm.dev_attr.attr,
 182         &sensor_dev_attr_in2_input.dev_attr.attr,
 183         &sensor_dev_attr_in2_min_alarm.dev_attr.attr,
 184         &sensor_dev_attr_in2_max_alarm.dev_attr.attr,
 185
 186         &sensor_dev_attr_curr1_input.dev_attr.attr,
 187         &sensor_dev_attr_curr1_max_alarm.dev_attr.attr,
 188
 189         NULL,
 190 };
 191 ATTRIBUTE_GROUPS(ltc4261);
 192
 193 static int ltc4261_probe(struct i2c_client *client,
 194                          const struct i2c_device_id *id)
 195 {
 196         struct i2c_adapter *adapter = client->adapter;
 197         struct device *dev = &client->dev;
 198         struct ltc4261_data *data;
 199         struct device *hwmon_dev;
 200
 201         if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
 202                 return -ENODEV;
 203
 204         if (i2c_smbus_read_byte_data(client, LTC4261_STATUS) < 0) {
 205                 dev_err(dev, "Failed to read status register\n");
 206                 return -ENODEV;
 207         }
 208
 209         data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
 210         if (!data)
 211                 return -ENOMEM;
 212
 213         data->client = client;
 214         mutex_init(&data->update_lock);
 215
 216         /* Clear faults */
 217         i2c_smbus_write_byte_data(client, LTC4261_FAULT, 0x00);
 218
 219         hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
 220                                                            data,
 221                                                            ltc4261_groups);
 222         return PTR_ERR_OR_ZERO(hwmon_dev);
 223 }
 224
 225 static const struct i2c_device_id ltc4261_id[] = {
 226         {"ltc4261", 0},
 227         {}
 228 };
 229
 230 MODULE_DEVICE_TABLE(i2c, ltc4261_id);
 231
 232 /* This is the driver that will be inserted */
 233 static struct i2c_driver ltc4261_driver = {
 234         .driver = {
 235                    .name = "ltc4261",
 236                    },
 237         .probe = ltc4261_probe,
 238         .id_table = ltc4261_id,
 239 };
 240
 241 module_i2c_driver(ltc4261_driver);
 242
 243 MODULE_AUTHOR("Guenter Roeck <linux@roeck-us.net>");
 244 MODULE_DESCRIPTION("LTC4261 driver");
 245 MODULE_LICENSE("GPL");