1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Driver for Linear Technology LTC4151 High Voltage I2C Current 4 * and Voltage Monitor 5 * 6 * Copyright (C) 2011 AppearTV AS 7 * 8 * Derived from: 9 * 10 * Driver for Linear Technology LTC4261 I2C Negative Voltage Hot 11 * Swap Controller 12 * Copyright (C) 2010 Ericsson AB. 13 * 14 * Datasheet: http://www.linear.com/docs/Datasheet/4151fc.pdf 15 */ 16 17 #include <linux/kernel.h> 18 #include <linux/module.h> 19 #include <linux/of.h> 20 #include <linux/init.h> 21 #include <linux/err.h> 22 #include <linux/slab.h> 23 #include <linux/i2c.h> 24 #include <linux/hwmon.h> 25 #include <linux/hwmon-sysfs.h> 26 #include <linux/jiffies.h> 27 28 /* chip registers */ 29 #define LTC4151_SENSE_H 0x00 30 #define LTC4151_SENSE_L 0x01 31 #define LTC4151_VIN_H 0x02 32 #define LTC4151_VIN_L 0x03 33 #define LTC4151_ADIN_H 0x04 34 #define LTC4151_ADIN_L 0x05 35 36 struct ltc4151_data { 37 struct i2c_client *client; 38 39 struct mutex update_lock; 40 bool valid; 41 unsigned long last_updated; /* in jiffies */ 42 unsigned int shunt; /* in micro ohms */ 43 44 /* Registers */ 45 u8 regs[6]; 46 }; 47 48 static struct ltc4151_data *ltc4151_update_device(struct device *dev) 49 { 50 struct ltc4151_data *data = dev_get_drvdata(dev); 51 struct i2c_client *client = data->client; 52 struct ltc4151_data *ret = data; 53 54 mutex_lock(&data->update_lock); 55 56 /* 57 * The chip's A/D updates 6 times per second 58 * (Conversion Rate 6 - 9 Hz) 59 */ 60 if (time_after(jiffies, data->last_updated + HZ / 6) || !data->valid) { 61 int i; 62 63 dev_dbg(&client->dev, "Starting ltc4151 update\n"); 64 65 /* Read all registers */ 66 for (i = 0; i < ARRAY_SIZE(data->regs); i++) { 67 int val; 68 69 val = i2c_smbus_read_byte_data(client, i); 70 if (unlikely(val < 0)) { 71 dev_dbg(dev, 72 "Failed to read ADC value: error %d\n", 73 val); 74 ret = ERR_PTR(val); 75 goto abort; 76 } 77 data->regs[i] = val; 78 } 79 data->last_updated = jiffies; 80 data->valid = true; 81 } 82 abort: 83 mutex_unlock(&data->update_lock); 84 return ret; 85 } 86 87 /* Return the voltage from the given register in mV */ 88 static int ltc4151_get_value(struct ltc4151_data *data, u8 reg) 89 { 90 u32 val; 91 92 val = (data->regs[reg] << 4) + (data->regs[reg + 1] >> 4); 93 94 switch (reg) { 95 case LTC4151_ADIN_H: 96 /* 500uV resolution. Convert to mV. */ 97 val = val * 500 / 1000; 98 break; 99 case LTC4151_SENSE_H: 100 /* 101 * 20uV resolution. Convert to current as measured with 102 * a given sense resistor, in mA. 103 */ 104 val = val * 20 * 1000 / data->shunt; 105 break; 106 case LTC4151_VIN_H: 107 /* 25 mV per increment */ 108 val = val * 25; 109 break; 110 default: 111 /* If we get here, the developer messed up */ 112 WARN_ON_ONCE(1); 113 val = 0; 114 break; 115 } 116 117 return val; 118 } 119 120 static ssize_t ltc4151_value_show(struct device *dev, 121 struct device_attribute *da, char *buf) 122 { 123 struct sensor_device_attribute *attr = to_sensor_dev_attr(da); 124 struct ltc4151_data *data = ltc4151_update_device(dev); 125 int value; 126 127 if (IS_ERR(data)) 128 return PTR_ERR(data); 129 130 value = ltc4151_get_value(data, attr->index); 131 return sysfs_emit(buf, "%d\n", value); 132 } 133 134 /* 135 * Input voltages. 136 */ 137 static SENSOR_DEVICE_ATTR_RO(in1_input, ltc4151_value, LTC4151_VIN_H); 138 static SENSOR_DEVICE_ATTR_RO(in2_input, ltc4151_value, LTC4151_ADIN_H); 139 140 /* Currents (via sense resistor) */ 141 static SENSOR_DEVICE_ATTR_RO(curr1_input, ltc4151_value, LTC4151_SENSE_H); 142 143 /* 144 * Finally, construct an array of pointers to members of the above objects, 145 * as required for sysfs_create_group() 146 */ 147 static struct attribute *ltc4151_attrs[] = { 148 &sensor_dev_attr_in1_input.dev_attr.attr, 149 &sensor_dev_attr_in2_input.dev_attr.attr, 150 151 &sensor_dev_attr_curr1_input.dev_attr.attr, 152 153 NULL, 154 }; 155 ATTRIBUTE_GROUPS(ltc4151); 156 157 static int ltc4151_probe(struct i2c_client *client) 158 { 159 struct i2c_adapter *adapter = client->adapter; 160 struct device *dev = &client->dev; 161 struct ltc4151_data *data; 162 struct device *hwmon_dev; 163 u32 shunt; 164 165 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)) 166 return -ENODEV; 167 168 data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL); 169 if (!data) 170 return -ENOMEM; 171 172 if (of_property_read_u32(client->dev.of_node, 173 "shunt-resistor-micro-ohms", &shunt)) 174 shunt = 1000; /* 1 mOhm if not set via DT */ 175 176 if (shunt == 0) 177 return -EINVAL; 178 179 data->shunt = shunt; 180 181 data->client = client; 182 mutex_init(&data->update_lock); 183 184 hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name, 185 data, 186 ltc4151_groups); 187 return PTR_ERR_OR_ZERO(hwmon_dev); 188 } 189 190 static const struct i2c_device_id ltc4151_id[] = { 191 { "ltc4151", 0 }, 192 { } 193 }; 194 MODULE_DEVICE_TABLE(i2c, ltc4151_id); 195 196 static const struct of_device_id __maybe_unused ltc4151_match[] = { 197 { .compatible = "lltc,ltc4151" }, 198 {}, 199 }; 200 MODULE_DEVICE_TABLE(of, ltc4151_match); 201 202 /* This is the driver that will be inserted */ 203 static struct i2c_driver ltc4151_driver = { 204 .driver = { 205 .name = "ltc4151", 206 .of_match_table = of_match_ptr(ltc4151_match), 207 }, 208 .probe_new = ltc4151_probe, 209 .id_table = ltc4151_id, 210 }; 211 212 module_i2c_driver(ltc4151_driver); 213 214 MODULE_AUTHOR("Per Dalen <per.dalen@appeartv.com>"); 215 MODULE_DESCRIPTION("LTC4151 driver"); 216 MODULE_LICENSE("GPL"); 217