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/Documentation/hwmon/ltc4151 b/Documentation/hwmon/ltc4151
new file mode 100644 (file)
index 0000000..43c667e
--- /dev/null
+++ b/Documentation/hwmon/ltc4151
@@ -0,0 +1,47 @@
+Kernel driver ltc4151
+=====================
+
+Supported chips:
+  * Linear Technology LTC4151
+    Prefix: 'ltc4151'
+    Addresses scanned: -
+    Datasheet:
+        http://www.linear.com/docs/Datasheet/4151fc.pdf
+
+Author: Per Dalen <per.dalen@appeartv.com>
+
+
+Description
+-----------
+
+The LTC4151 is a High Voltage I2C Current and Voltage Monitor.
+
+
+Usage Notes
+-----------
+
+This driver does not probe for LTC4151 devices, since there is no register
+which can be safely used to identify the chip. You will have to instantiate
+the devices explicitly.
+
+Example: the following will load the driver for an LTC4151 at address 0x6f
+on I2C bus #0:
+# modprobe ltc4151
+# echo ltc4151 0x6f > /sys/bus/i2c/devices/i2c-0/new_device
+
+
+Sysfs entries
+-------------
+
+Voltage readings provided by this driver are reported as obtained from the ADIN
+and VIN registers.
+
+Current reading provided by this driver is reported as obtained from the Current
+Sense register. The reported value assumes that a 1 mOhm sense resistor is
+installed.
+
+in1_input              VDIN voltage (mV)
+
+in2_input              ADIN voltage (mV)
+
+curr1_input            SENSE current (mA)

diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 19b0af4..7bda622 100644 (file)
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -636,6 +636,17 @@ config SENSORS_LM93
          This driver can also be built as a module.  If so, the module
          will be called lm93.
 
+config SENSORS_LTC4151
+       tristate "Linear Technology LTC4151"
+       depends on I2C
+       default n
+       help
+         If you say yes here you get support for Linear Technology LTC4151
+         High Voltage I2C Current and Voltage Monitor interface.
+
+         This driver can also be built as a module. If so, the module will
+         be called ltc4151.
+
 config SENSORS_LTC4215
        tristate "Linear Technology LTC4215"
        depends on I2C && EXPERIMENTAL

diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index feacc7c..bd0410e 100644 (file)
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -80,6 +80,7 @@ obj-$(CONFIG_SENSORS_LM90)    += lm90.o
 obj-$(CONFIG_SENSORS_LM92)     += lm92.o
 obj-$(CONFIG_SENSORS_LM93)     += lm93.o
 obj-$(CONFIG_SENSORS_LM95241)  += lm95241.o
+obj-$(CONFIG_SENSORS_LTC4151)  += ltc4151.o
 obj-$(CONFIG_SENSORS_LTC4215)  += ltc4215.o
 obj-$(CONFIG_SENSORS_LTC4245)  += ltc4245.o
 obj-$(CONFIG_SENSORS_LTC4261)  += ltc4261.o

diff --git a/drivers/hwmon/ltc4151.c b/drivers/hwmon/ltc4151.c
new file mode 100644 (file)
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, &ltc4151_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, &ltc4151_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, &ltc4151_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(&ltc4151_driver);
+}
+
+static void __exit ltc4151_exit(void)
+{
+       i2c_del_driver(&ltc4151_driver);
+}
+
+MODULE_AUTHOR("Per Dalen <per.dalen@appeartv.com>");
+MODULE_DESCRIPTION("LTC4151 driver");
+MODULE_LICENSE("GPL");
+
+module_init(ltc4151_init);
+module_exit(ltc4151_exit);