hwmon: Add support for LTC4151
LTC4151 is High Voltage I2C Current and Voltage Monitor from Linear
Technology.
Signed-off-by: Per Dalen <per.dalen@appeartv.com>
Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
diff --git a/drivers/hwmon/ltc4151.c b/drivers/hwmon/ltc4151.c
new file mode 100644
index 0000000..4ac06b7
--- /dev/null
+++ b/drivers/hwmon/ltc4151.c
@@ -0,0 +1,256 @@
+/*
+ * Driver for Linear Technology LTC4151 High Voltage I2C Current
+ * and Voltage Monitor
+ *
+ * Copyright (C) 2011 AppearTV AS
+ *
+ * Derived from:
+ *
+ * Driver for Linear Technology LTC4261 I2C Negative Voltage Hot
+ * Swap Controller
+ * Copyright (C) 2010 Ericsson AB.
+ *
+ * Datasheet: http://www.linear.com/docs/Datasheet/4151fc.pdf
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/err.h>
+#include <linux/slab.h>
+#include <linux/i2c.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+
+/* chip registers */
+#define LTC4151_SENSE_H 0x00
+#define LTC4151_SENSE_L 0x01
+#define LTC4151_VIN_H 0x02
+#define LTC4151_VIN_L 0x03
+#define LTC4151_ADIN_H 0x04
+#define LTC4151_ADIN_L 0x05
+
+struct ltc4151_data {
+ struct device *hwmon_dev;
+
+ struct mutex update_lock;
+ bool valid;
+ unsigned long last_updated; /* in jiffies */
+
+ /* Registers */
+ u8 regs[6];
+};
+
+static struct ltc4151_data *ltc4151_update_device(struct device *dev)
+{
+ struct i2c_client *client = to_i2c_client(dev);
+ struct ltc4151_data *data = i2c_get_clientdata(client);
+ struct ltc4151_data *ret = data;
+
+ mutex_lock(&data->update_lock);
+
+ /*
+ * The chip's A/D updates 6 times per second
+ * (Conversion Rate 6 - 9 Hz)
+ */
+ if (time_after(jiffies, data->last_updated + HZ / 6) || !data->valid) {
+ int i;
+
+ dev_dbg(&client->dev, "Starting ltc4151 update\n");
+
+ /* Read all registers */
+ for (i = 0; i < ARRAY_SIZE(data->regs); i++) {
+ int val;
+
+ val = i2c_smbus_read_byte_data(client, i);
+ if (unlikely(val < 0)) {
+ dev_dbg(dev,
+ "Failed to read ADC value: error %d\n",
+ val);
+ ret = ERR_PTR(val);
+ goto abort;
+ }
+ data->regs[i] = val;
+ }
+ data->last_updated = jiffies;
+ data->valid = 1;
+ }
+abort:
+ mutex_unlock(&data->update_lock);
+ return ret;
+}
+
+/* Return the voltage from the given register in mV */
+static int ltc4151_get_value(struct ltc4151_data *data, u8 reg)
+{
+ u32 val;
+
+ val = (data->regs[reg] << 4) + (data->regs[reg + 1] >> 4);
+
+ switch (reg) {
+ case LTC4151_ADIN_H:
+ /* 500uV resolution. Convert to mV. */
+ val = val * 500 / 1000;
+ break;
+ case LTC4151_SENSE_H:
+ /*
+ * 20uV resolution. Convert to current as measured with
+ * an 1 mOhm sense resistor, in mA.
+ */
+ val = val * 20;
+ break;
+ case LTC4151_VIN_H:
+ /* 25 mV per increment */
+ val = val * 25;
+ break;
+ default:
+ /* If we get here, the developer messed up */
+ WARN_ON_ONCE(1);
+ val = 0;
+ break;
+ }
+
+ return val;
+}
+
+static ssize_t ltc4151_show_value(struct device *dev,
+ struct device_attribute *da, char *buf)
+{
+ struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
+ struct ltc4151_data *data = ltc4151_update_device(dev);
+ int value;
+
+ if (IS_ERR(data))
+ return PTR_ERR(data);
+
+ value = ltc4151_get_value(data, attr->index);
+ return snprintf(buf, PAGE_SIZE, "%d\n", value);
+}
+
+/*
+ * Input voltages.
+ */
+static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, \
+ ltc4151_show_value, NULL, LTC4151_VIN_H);
+static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, \
+ ltc4151_show_value, NULL, LTC4151_ADIN_H);
+
+/* Currents (via sense resistor) */
+static SENSOR_DEVICE_ATTR(curr1_input, S_IRUGO, \
+ ltc4151_show_value, NULL, LTC4151_SENSE_H);
+
+/* Finally, construct an array of pointers to members of the above objects,
+ * as required for sysfs_create_group()
+ */
+static struct attribute *ltc4151_attributes[] = {
+ &sensor_dev_attr_in1_input.dev_attr.attr,
+ &sensor_dev_attr_in2_input.dev_attr.attr,
+
+ &sensor_dev_attr_curr1_input.dev_attr.attr,
+
+ NULL,
+};
+
+static const struct attribute_group ltc4151_group = {
+ .attrs = ltc4151_attributes,
+};
+
+static int ltc4151_probe(struct i2c_client *client,
+ const struct i2c_device_id *id)
+{
+ struct i2c_adapter *adapter = client->adapter;
+ struct ltc4151_data *data;
+ int ret;
+
+ if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
+ return -ENODEV;
+
+ data = kzalloc(sizeof(*data), GFP_KERNEL);
+ if (!data) {
+ ret = -ENOMEM;
+ goto out_kzalloc;
+ }
+
+ i2c_set_clientdata(client, data);
+ mutex_init(&data->update_lock);
+
+ /* Register sysfs hooks */
+ ret = sysfs_create_group(&client->dev.kobj, <c4151_group);
+ if (ret)
+ goto out_sysfs_create_group;
+
+ data->hwmon_dev = hwmon_device_register(&client->dev);
+ if (IS_ERR(data->hwmon_dev)) {
+ ret = PTR_ERR(data->hwmon_dev);
+ goto out_hwmon_device_register;
+ }
+
+ return 0;
+
+out_hwmon_device_register:
+ sysfs_remove_group(&client->dev.kobj, <c4151_group);
+out_sysfs_create_group:
+ kfree(data);
+out_kzalloc:
+ return ret;
+}
+
+static int ltc4151_remove(struct i2c_client *client)
+{
+ struct ltc4151_data *data = i2c_get_clientdata(client);
+
+ hwmon_device_unregister(data->hwmon_dev);
+ sysfs_remove_group(&client->dev.kobj, <c4151_group);
+
+ kfree(data);
+
+ return 0;
+}
+
+static const struct i2c_device_id ltc4151_id[] = {
+ { "ltc4151", 0 },
+ { }
+};
+MODULE_DEVICE_TABLE(i2c, ltc4151_id);
+
+/* This is the driver that will be inserted */
+static struct i2c_driver ltc4151_driver = {
+ .driver = {
+ .name = "ltc4151",
+ },
+ .probe = ltc4151_probe,
+ .remove = ltc4151_remove,
+ .id_table = ltc4151_id,
+};
+
+static int __init ltc4151_init(void)
+{
+ return i2c_add_driver(<c4151_driver);
+}
+
+static void __exit ltc4151_exit(void)
+{
+ i2c_del_driver(<c4151_driver);
+}
+
+MODULE_AUTHOR("Per Dalen <per.dalen@appeartv.com>");
+MODULE_DESCRIPTION("LTC4151 driver");
+MODULE_LICENSE("GPL");
+
+module_init(ltc4151_init);
+module_exit(ltc4151_exit);