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 = false; 77 goto abort; 78 } 79 data->regs[i] = val; 80 } 81 data->last_updated = jiffies; 82 data->valid = true; 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 sysfs_emit(buf, "%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 sysfs_emit(buf, "%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 { 195 struct i2c_adapter *adapter = client->adapter; 196 struct device *dev = &client->dev; 197 struct ltc4261_data *data; 198 struct device *hwmon_dev; 199 200 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)) 201 return -ENODEV; 202 203 if (i2c_smbus_read_byte_data(client, LTC4261_STATUS) < 0) { 204 dev_err(dev, "Failed to read status register\n"); 205 return -ENODEV; 206 } 207 208 data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL); 209 if (!data) 210 return -ENOMEM; 211 212 data->client = client; 213 mutex_init(&data->update_lock); 214 215 /* Clear faults */ 216 i2c_smbus_write_byte_data(client, LTC4261_FAULT, 0x00); 217 218 hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name, 219 data, 220 ltc4261_groups); 221 return PTR_ERR_OR_ZERO(hwmon_dev); 222 } 223 224 static const struct i2c_device_id ltc4261_id[] = { 225 {"ltc4261", 0}, 226 {} 227 }; 228 229 MODULE_DEVICE_TABLE(i2c, ltc4261_id); 230 231 /* This is the driver that will be inserted */ 232 static struct i2c_driver ltc4261_driver = { 233 .driver = { 234 .name = "ltc4261", 235 }, 236 .probe = ltc4261_probe, 237 .id_table = ltc4261_id, 238 }; 239 240 module_i2c_driver(ltc4261_driver); 241 242 MODULE_AUTHOR("Guenter Roeck <linux@roeck-us.net>"); 243 MODULE_DESCRIPTION("LTC4261 driver"); 244 MODULE_LICENSE("GPL"); 245