hwmon: INA219 and INA226 support

Add support for the Texas Instruments INA219 and INA226 power monitors.
Signed-off-by: Lothar Felten <l-felten@ti.com>
[guenter.roeck@ericsson.com: formatting cleanup; check for smbus word data;
 select PGA=8 for INA219]
Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>

Documentation/hwmon/ina2xx

+Kernel driver ina2xx
+====================
+
+Supported chips:
+  * Texas Instruments INA219
+    Prefix: 'ina219'
+    Addresses: I2C 0x40 - 0x4f
+    Datasheet: Publicly available at the Texas Instruments website
+               http://www.ti.com/
+
+  * Texas Instruments INA226
+    Prefix: 'ina226'
+    Addresses: I2C 0x40 - 0x4f
+    Datasheet: Publicly available at the Texas Instruments website
+               http://www.ti.com/
+
+Author: Lothar Felten <l-felten@ti.com>
+
+Description
+-----------
+
+The INA219 is a high-side current shunt and power monitor with an I2C
+interface. The INA219 monitors both shunt drop and supply voltage, with
+programmable conversion times and filtering.
+
+The INA226 is a current shunt and power monitor with an I2C interface.
+The INA226 monitors both a shunt voltage drop and bus supply voltage.
+
+The shunt value in micro-ohms can be set via platform data.

drivers/hwmon/Kconfig

@@ -1102,6 +1102,19 @@ config SENSORS_AMC6821
 	  This driver can also be build as a module.  If so, the module
 	  will be called amc6821.
 
+config SENSORS_INA2XX
+	tristate "Texas Instruments INA219, INA226"
+	depends on I2C && EXPERIMENTAL
+	help
+	  If you say yes here you get support for INA219 and INA226 power
+	  monitor chips.
+
+	  The INA2xx driver is configured for the default configuration of
+	  the part as described in the datasheet.
+	  Default value for Rshunt is 10 mOhms.
+	  This driver can also be built as a module.  If so, the module
+	  will be called ina2xx.
+
 config SENSORS_THMC50
 	tristate "Texas Instruments THMC50 / Analog Devices ADM1022"
 	depends on I2C

drivers/hwmon/Makefile

@@ -62,6 +62,7 @@ obj-$(CONFIG_SENSORS_ULTRA45)	+= ultra45_env.o
 obj-$(CONFIG_SENSORS_I5K_AMB)	+= i5k_amb.o
 obj-$(CONFIG_SENSORS_IBMAEM)	+= ibmaem.o
 obj-$(CONFIG_SENSORS_IBMPEX)	+= ibmpex.o
+obj-$(CONFIG_SENSORS_INA2XX)	+= ina2xx.o
 obj-$(CONFIG_SENSORS_IT87)	+= it87.o
 obj-$(CONFIG_SENSORS_JC42)	+= jc42.o
 obj-$(CONFIG_SENSORS_JZ4740)	+= jz4740-hwmon.o

drivers/hwmon/ina2xx.c

+/*
+ * Driver for Texas Instruments INA219, INA226 power monitor chips
+ *
+ * INA219:
+ * Zero Drift Bi-Directional Current/Power Monitor with I2C Interface
+ * Datasheet: http://www.ti.com/product/ina219
+ *
+ * INA226:
+ * Bi-Directional Current/Power Monitor with I2C Interface
+ * Datasheet: http://www.ti.com/product/ina226
+ *
+ * Copyright (C) 2012 Lothar Felten <l-felten@ti.com>
+ * Thanks to Jan Volkering
+ *
+ * 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; version 2 of the License.
+ */
+
+#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>
+
+#include <linux/platform_data/ina2xx.h>
+
+/* common register definitions */
+#define INA2XX_CONFIG			0x00
+#define INA2XX_SHUNT_VOLTAGE		0x01 /* readonly */
+#define INA2XX_BUS_VOLTAGE		0x02 /* readonly */
+#define INA2XX_POWER			0x03 /* readonly */
+#define INA2XX_CURRENT			0x04 /* readonly */
+#define INA2XX_CALIBRATION		0x05
+
+/* INA226 register definitions */
+#define INA226_MASK_ENABLE		0x06
+#define INA226_ALERT_LIMIT		0x07
+#define INA226_DIE_ID			0xFF
+
+
+/* register count */
+#define INA219_REGISTERS		6
+#define INA226_REGISTERS		8
+
+#define INA2XX_MAX_REGISTERS		8
+
+/* settings - depend on use case */
+#define INA219_CONFIG_DEFAULT		0x399F	/* PGA=8 */
+#define INA226_CONFIG_DEFAULT		0x4527	/* averages=16 */
+
+/* worst case is 68.10 ms (~14.6Hz, ina219) */
+#define INA2XX_CONVERSION_RATE		15
+
+enum ina2xx_ids { ina219, ina226 };
+
+struct ina2xx_data {
+	struct device *hwmon_dev;
+
+	struct mutex update_lock;
+	bool valid;
+	unsigned long last_updated;
+
+	int kind;
+	int registers;
+	u16 regs[INA2XX_MAX_REGISTERS];
+};
+
+int ina2xx_read_word(struct i2c_client *client, int reg)
+{
+	int val = i2c_smbus_read_word_data(client, reg);
+	if (unlikely(val < 0)) {
+		dev_dbg(&client->dev,
+			"Failed to read register: %d\n", reg);
+		return val;
+	}
+	return be16_to_cpu(val);
+}
+
+void ina2xx_write_word(struct i2c_client *client, int reg, int data)
+{
+	i2c_smbus_write_word_data(client, reg, cpu_to_be16(data));
+}
+
+static struct ina2xx_data *ina2xx_update_device(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct ina2xx_data *data = i2c_get_clientdata(client);
+	struct ina2xx_data *ret = data;
+
+	mutex_lock(&data->update_lock);
+
+	if (time_after(jiffies, data->last_updated +
+		       HZ / INA2XX_CONVERSION_RATE) || !data->valid) {
+
+		int i;
+
+		dev_dbg(&client->dev, "Starting ina2xx update\n");
+
+		/* Read all registers */
+		for (i = 0; i < data->registers; i++) {
+			int rv = ina2xx_read_word(client, i);
+			if (rv < 0) {
+				ret = ERR_PTR(rv);
+				goto abort;
+			}
+			data->regs[i] = rv;
+		}
+		data->last_updated = jiffies;
+		data->valid = 1;
+	}
+abort:
+	mutex_unlock(&data->update_lock);
+	return ret;
+}
+
+static int ina219_get_value(struct ina2xx_data *data, u8 reg)
+{
+	/*
+	 * calculate exact value for the given register
+	 * we assume default power-on reset settings:
+	 * bus voltage range 32V
+	 * gain = /8
+	 * adc 1 & 2 -> conversion time 532uS
+	 * mode is continuous shunt and bus
+	 * calibration value is INA219_CALIBRATION_VALUE
+	 */
+	int val = data->regs[reg];
+
+	switch (reg) {
+	case INA2XX_SHUNT_VOLTAGE:
+		/* LSB=10uV. Convert to mV. */
+		val = DIV_ROUND_CLOSEST(val, 100);
+		break;
+	case INA2XX_BUS_VOLTAGE:
+		/* LSB=4mV. Register is not right aligned, convert to mV. */
+		val = (val >> 3) * 4;
+		break;
+	case INA2XX_POWER:
+		/* LSB=20mW. Convert to uW */
+		val = val * 20 * 1000;
+		break;
+	case INA2XX_CURRENT:
+		/* LSB=1mA (selected). Is in mA */
+		break;
+	default:
+		/* programmer goofed */
+		WARN_ON_ONCE(1);
+		val = 0;
+		break;
+	}
+
+	return val;
+}
+
+static int ina226_get_value(struct ina2xx_data *data, u8 reg)
+{
+	/*
+	 * calculate exact value for the given register
+	 * we assume default power-on reset settings:
+	 * bus voltage range 32V
+	 * gain = /8
+	 * adc 1 & 2 -> conversion time 532uS
+	 * mode is continuous shunt and bus
+	 * calibration value is INA226_CALIBRATION_VALUE
+	 */
+	int val = data->regs[reg];
+
+	switch (reg) {
+	case INA2XX_SHUNT_VOLTAGE:
+		/* LSB=2.5uV. Convert to mV. */
+		val = DIV_ROUND_CLOSEST(val, 400);
+		break;
+	case INA2XX_BUS_VOLTAGE:
+		/* LSB=1.25mV. Convert to mV. */
+		val = val + DIV_ROUND_CLOSEST(val, 4);
+		break;
+	case INA2XX_POWER:
+		/* LSB=25mW. Convert to uW */
+		val = val * 25 * 1000;
+		break;
+	case INA2XX_CURRENT:
+		/* LSB=1mA (selected). Is in mA */
+		break;
+	default:
+		/* programmer goofed */
+		WARN_ON_ONCE(1);
+		val = 0;
+		break;
+	}
+
+	return val;
+}
+
+static ssize_t ina2xx_show_value(struct device *dev,
+				 struct device_attribute *da, char *buf)
+{
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
+	struct ina2xx_data *data = ina2xx_update_device(dev);
+	int value = 0;
+
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
+	switch (data->kind) {
+	case ina219:
+		value = ina219_get_value(data, attr->index);
+		break;
+	case ina226:
+		value = ina226_get_value(data, attr->index);
+		break;
+	default:
+		WARN_ON_ONCE(1);
+		break;
+	}
+	return snprintf(buf, PAGE_SIZE, "%d\n", value);
+}
+
+/* shunt voltage */
+static SENSOR_DEVICE_ATTR(in0_input, S_IRUGO, \
+	ina2xx_show_value, NULL, INA2XX_SHUNT_VOLTAGE);
+
+/* bus voltage */
+static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, \
+	ina2xx_show_value, NULL, INA2XX_BUS_VOLTAGE);
+
+/* calculated current */
+static SENSOR_DEVICE_ATTR(curr1_input, S_IRUGO, \
+	ina2xx_show_value, NULL, INA2XX_CURRENT);
+
+/* calculated power */
+static SENSOR_DEVICE_ATTR(power1_input, S_IRUGO, \
+	ina2xx_show_value, NULL, INA2XX_POWER);
+
+/* pointers to created device attributes */
+static struct attribute *ina2xx_attributes[] = {
+	&sensor_dev_attr_in0_input.dev_attr.attr,
+	&sensor_dev_attr_in1_input.dev_attr.attr,
+	&sensor_dev_attr_curr1_input.dev_attr.attr,
+	&sensor_dev_attr_power1_input.dev_attr.attr,
+	NULL,
+};
+
+static const struct attribute_group ina2xx_group = {
+	.attrs = ina2xx_attributes,
+};
+
+static int ina2xx_probe(struct i2c_client *client,
+			const struct i2c_device_id *id)
+{
+	struct i2c_adapter *adapter = client->adapter;
+	struct ina2xx_data *data;
+	struct ina2xx_platform_data *pdata;
+	int ret = 0;
+	long shunt = 10000; /* default shunt value 10mOhms */
+
+	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_WORD_DATA))
+		return -ENODEV;
+
+	data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	if (client->dev.platform_data) {
+		pdata =
+		  (struct ina2xx_platform_data *)client->dev.platform_data;
+		shunt = pdata->shunt_uohms;
+	}
+
+	if (shunt <= 0)
+		return -ENODEV;
+
+	/* set the device type */
+	data->kind = id->driver_data;
+
+	switch (data->kind) {
+	case ina219:
+		/* device configuration */
+		ina2xx_write_word(client, INA2XX_CONFIG, INA219_CONFIG_DEFAULT);
+
+		/* set current LSB to 1mA, shunt is in uOhms */
+		/* (equation 13 in datasheet) */
+		ina2xx_write_word(client, INA2XX_CALIBRATION, 40960000 / shunt);
+		dev_info(&client->dev,
+			 "power monitor INA219 (Rshunt = %li uOhm)\n", shunt);
+		data->registers = INA219_REGISTERS;
+		break;
+	case ina226:
+		/* device configuration */
+		ina2xx_write_word(client, INA2XX_CONFIG, INA226_CONFIG_DEFAULT);
+
+		/* set current LSB to 1mA, shunt is in uOhms */
+		/* (equation 1 in datasheet)*/
+		ina2xx_write_word(client, INA2XX_CALIBRATION, 5120000 / shunt);
+		dev_info(&client->dev,
+			 "power monitor INA226 (Rshunt = %li uOhm)\n", shunt);
+		data->registers = INA226_REGISTERS;
+		break;
+	default:
+		/* unknown device id */
+		return -ENODEV;
+	}
+
+	i2c_set_clientdata(client, data);
+	mutex_init(&data->update_lock);
+
+	ret = sysfs_create_group(&client->dev.kobj, &ina2xx_group);
+	if (ret)
+		return ret;
+
+	data->hwmon_dev = hwmon_device_register(&client->dev);
+	if (IS_ERR(data->hwmon_dev)) {
+		ret = PTR_ERR(data->hwmon_dev);
+		goto out_err_hwmon;
+	}
+
+	return 0;
+
+out_err_hwmon:
+	sysfs_remove_group(&client->dev.kobj, &ina2xx_group);
+	return ret;
+}
+
+static int ina2xx_remove(struct i2c_client *client)
+{
+	struct ina2xx_data *data = i2c_get_clientdata(client);
+
+	hwmon_device_unregister(data->hwmon_dev);
+	sysfs_remove_group(&client->dev.kobj, &ina2xx_group);
+
+	return 0;
+}
+
+static const struct i2c_device_id ina2xx_id[] = {
+	{ "ina219", ina219 },
+	{ "ina226", ina226 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, ina2xx_id);
+
+static struct i2c_driver ina2xx_driver = {
+	.driver = {
+		.name	= "ina2xx",
+	},
+	.probe		= ina2xx_probe,
+	.remove		= ina2xx_remove,
+	.id_table	= ina2xx_id,
+};
+
+static int __init ina2xx_init(void)
+{
+	return i2c_add_driver(&ina2xx_driver);
+}
+
+static void __exit ina2xx_exit(void)
+{
+	i2c_del_driver(&ina2xx_driver);
+}
+
+MODULE_AUTHOR("Lothar Felten <l-felten@ti.com>");
+MODULE_DESCRIPTION("ina2xx driver");
+MODULE_LICENSE("GPL");
+
+module_init(ina2xx_init);
+module_exit(ina2xx_exit);

include/linux/platform_data/ina2xx.h

+/*
+ * Driver for Texas Instruments INA219, INA226 power monitor chips
+ *
+ * Copyright (C) 2012 Lothar Felten <l-felten@ti.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * For further information, see the Documentation/hwmon/ina2xx file.
+ */
+
+/**
+ * struct ina2xx_platform_data - ina2xx info
+ * @shunt_uohms		shunt resistance in microohms
+ */
+struct ina2xx_platform_data {
+	long shunt_uohms;
+};