1 // SPDX-License-Identifier: GPL-2.0-or-later
3  * Driver for Linear Technology LTC4151 High Voltage I2C Current
25 #include <linux/hwmon-sysfs.h>
42 	unsigned int shunt; /* in micro ohms */  member
51 	struct i2c_client *client = data->client;  in ltc4151_update_device()
54 	mutex_lock(&data->update_lock);  in ltc4151_update_device()
58 	 * (Conversion Rate 6 - 9 Hz)  in ltc4151_update_device()
60 	if (time_after(jiffies, data->last_updated + HZ / 6) || !data->valid) {  in ltc4151_update_device()
63 		dev_dbg(&client->dev, "Starting ltc4151 update\n");  in ltc4151_update_device()
66 		for (i = 0; i < ARRAY_SIZE(data->regs); i++) {  in ltc4151_update_device()
77 			data->regs[i] = val;  in ltc4151_update_device()
79 		data->last_updated = jiffies;  in ltc4151_update_device()
80 		data->valid = true;  in ltc4151_update_device()
83 	mutex_unlock(&data->update_lock);  in ltc4151_update_device()
92 	val = (data->regs[reg] << 4) + (data->regs[reg + 1] >> 4);  in ltc4151_get_value()
101 		 * 20uV resolution. Convert to current as measured with  in ltc4151_get_value()
102 		 * a given sense resistor, in mA.  in ltc4151_get_value()
104 		val = val * 20 * 1000 / data->shunt;  in ltc4151_get_value()
130 	value = ltc4151_get_value(data, attr->index);  in ltc4151_value_show()
140 /* Currents (via sense resistor) */
159 	struct i2c_adapter *adapter = client->adapter;  in ltc4151_probe()
160 	struct device *dev = &client->dev;  in ltc4151_probe()
163 	u32 shunt;  in ltc4151_probe()  local
166 		return -ENODEV;  in ltc4151_probe()
170 		return -ENOMEM;  in ltc4151_probe()
172 	if (of_property_read_u32(client->dev.of_node,  in ltc4151_probe()
173 				 "shunt-resistor-micro-ohms", &shunt))  in ltc4151_probe()
174 		shunt = 1000; /* 1 mOhm if not set via DT */  in ltc4151_probe()
176 	if (shunt == 0)  in ltc4151_probe()
177 		return -EINVAL;  in ltc4151_probe()
179 	data->shunt = shunt;  in ltc4151_probe()
181 	data->client = client;  in ltc4151_probe()
182 	mutex_init(&data->update_lock);  in ltc4151_probe()
184 	hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,  in ltc4151_probe()