drivers/hwmon/ltc4215.c - kernel/bruno - Git at Google

 /*
  * Driver for Linear Technology LTC4215 I2C Hot Swap Controller
  *
  * Copyright (C) 2009 Ira W. Snyder <iws@ovro.caltech.edu>
  *
  * 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.
  *
  * Datasheet:
  * http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1003,C1006,C1163,P17572,D12697
  */

 #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/jiffies.h>

 /* Here are names of the chip's registers (a.k.a. commands) */
 enum ltc4215_cmd {
 	LTC4215_CONTROL			= 0x00, /* rw */
 	LTC4215_ALERT			= 0x01, /* rw */
 	LTC4215_STATUS			= 0x02, /* ro */
 	LTC4215_FAULT			= 0x03, /* rw */
 	LTC4215_SENSE			= 0x04, /* rw */
 	LTC4215_SOURCE			= 0x05, /* rw */
 	LTC4215_ADIN			= 0x06, /* rw */
 };

 struct ltc4215_data {
 	struct i2c_client *client;

 	struct mutex update_lock;
 	bool valid;
 	unsigned long last_updated; /* in jiffies */

 	/* Registers */
 	u8 regs[7];
 };

 static struct ltc4215_data *ltc4215_update_device(struct device *dev)
 {
 	struct ltc4215_data *data = dev_get_drvdata(dev);
 	struct i2c_client *client = data->client;
 	s32 val;
 	int i;

 	mutex_lock(&data->update_lock);

 	/* The chip's A/D updates 10 times per second */
 	if (time_after(jiffies, data->last_updated + HZ / 10) || !data->valid) {

 		dev_dbg(&client->dev, "Starting ltc4215 update\n");

 		/* Read all registers */
 		for (i = 0; i < ARRAY_SIZE(data->regs); i++) {
 			val = i2c_smbus_read_byte_data(client, i);
 			if (unlikely(val < 0))
 				data->regs[i] = 0;
 			else
 				data->regs[i] = val;
 		}

 		data->last_updated = jiffies;
 		data->valid = 1;
 	}

 	mutex_unlock(&data->update_lock);

 	return data;
 }

 /* Return the voltage from the given register in millivolts */
 static int ltc4215_get_voltage(struct device *dev, u8 reg)
 {
 	struct ltc4215_data *data = ltc4215_update_device(dev);
 	const u8 regval = data->regs[reg];
 	u32 voltage = 0;

 	switch (reg) {
 	case LTC4215_SENSE:
 		/* 151 uV per increment */
 		voltage = regval * 151 / 1000;
 		break;
 	case LTC4215_SOURCE:
 		/* 60.5 mV per increment */
 		voltage = regval * 605 / 10;
 		break;
 	case LTC4215_ADIN:
 		/*
 		 * The ADIN input is divided by 12.5, and has 4.82 mV
 		 * per increment, so we have the additional multiply
 		 */
 		voltage = regval * 482 * 125 / 1000;
 		break;
 	default:
 		/* If we get here, the developer messed up */
 		WARN_ON_ONCE(1);
 		break;
 	}

 	return voltage;
 }

 /* Return the current from the sense resistor in mA */
 static unsigned int ltc4215_get_current(struct device *dev)
 {
 	struct ltc4215_data *data = ltc4215_update_device(dev);

 	/*
 	 * The strange looking conversions that follow are fixed-point
 	 * math, since we cannot do floating point in the kernel.
 	 *
 	 * Step 1: convert sense register to microVolts
 	 * Step 2: convert voltage to milliAmperes
 	 *
 	 * If you play around with the V=IR equation, you come up with
 	 * the following: X uV / Y mOhm == Z mA
 	 *
 	 * With the resistors that are fractions of a milliOhm, we multiply
 	 * the voltage and resistance by 10, to shift the decimal point.
 	 * Now we can use the normal division operator again.
 	 */

 	/* Calculate voltage in microVolts (151 uV per increment) */
 	const unsigned int voltage = data->regs[LTC4215_SENSE] * 151;

 	/* Calculate current in milliAmperes (4 milliOhm sense resistor) */
 	const unsigned int curr = voltage / 4;

 	return curr;
 }

 static ssize_t ltc4215_show_voltage(struct device *dev,
 				    struct device_attribute *da,
 				    char *buf)
 {
 	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
 	const int voltage = ltc4215_get_voltage(dev, attr->index);

 	return snprintf(buf, PAGE_SIZE, "%d\n", voltage);
 }

 static ssize_t ltc4215_show_current(struct device *dev,
 				    struct device_attribute *da,
 				    char *buf)
 {
 	const unsigned int curr = ltc4215_get_current(dev);

 	return snprintf(buf, PAGE_SIZE, "%u\n", curr);
 }

 static ssize_t ltc4215_show_power(struct device *dev,
 				  struct device_attribute *da,
 				  char *buf)
 {
 	const unsigned int curr = ltc4215_get_current(dev);
 	const int output_voltage = ltc4215_get_voltage(dev, LTC4215_ADIN);

 	/* current in mA * voltage in mV == power in uW */
 	const unsigned int power = abs(output_voltage * curr);

 	return snprintf(buf, PAGE_SIZE, "%u\n", power);
 }

 static ssize_t ltc4215_show_alarm(struct device *dev,
 					  struct device_attribute *da,
 					  char *buf)
 {
 	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
 	struct ltc4215_data *data = ltc4215_update_device(dev);
 	const u8 reg = data->regs[LTC4215_STATUS];
 	const u32 mask = attr->index;

 	return snprintf(buf, PAGE_SIZE, "%u\n", !!(reg & mask));
 }

 /*
  * These macros are used below in constructing device attribute objects
  * for use with sysfs_create_group() to make a sysfs device file
  * for each register.
  */

 /* Construct a sensor_device_attribute structure for each register */

 /* Current */
 static SENSOR_DEVICE_ATTR(curr1_input, S_IRUGO, ltc4215_show_current, NULL, 0);
 static SENSOR_DEVICE_ATTR(curr1_max_alarm, S_IRUGO, ltc4215_show_alarm, NULL,
 			  1 << 2);

 /* Power (virtual) */
 static SENSOR_DEVICE_ATTR(power1_input, S_IRUGO, ltc4215_show_power, NULL, 0);

 /* Input Voltage */
 static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, ltc4215_show_voltage, NULL,
 			  LTC4215_ADIN);
 static SENSOR_DEVICE_ATTR(in1_max_alarm, S_IRUGO, ltc4215_show_alarm, NULL,
 			  1 << 0);
 static SENSOR_DEVICE_ATTR(in1_min_alarm, S_IRUGO, ltc4215_show_alarm, NULL,
 			  1 << 1);

 /* Output Voltage */
 static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, ltc4215_show_voltage, NULL,
 			  LTC4215_SOURCE);
 static SENSOR_DEVICE_ATTR(in2_min_alarm, S_IRUGO, ltc4215_show_alarm, NULL,
 			  1 << 3);

 /*
  * Finally, construct an array of pointers to members of the above objects,
  * as required for sysfs_create_group()
  */
 static struct attribute *ltc4215_attrs[] = {
 	&sensor_dev_attr_curr1_input.dev_attr.attr,
 	&sensor_dev_attr_curr1_max_alarm.dev_attr.attr,

 	&sensor_dev_attr_power1_input.dev_attr.attr,

 	&sensor_dev_attr_in1_input.dev_attr.attr,
 	&sensor_dev_attr_in1_max_alarm.dev_attr.attr,
 	&sensor_dev_attr_in1_min_alarm.dev_attr.attr,

 	&sensor_dev_attr_in2_input.dev_attr.attr,
 	&sensor_dev_attr_in2_min_alarm.dev_attr.attr,

 	NULL,
 };
 ATTRIBUTE_GROUPS(ltc4215);

 static int ltc4215_probe(struct i2c_client *client,
 			 const struct i2c_device_id *id)
 {
 	struct i2c_adapter *adapter = client->adapter;
 	struct device *dev = &client->dev;
 	struct ltc4215_data *data;
 	struct device *hwmon_dev;

 	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
 		return -ENODEV;

 	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
 	if (!data)
 		return -ENOMEM;

 	data->client = client;
 	mutex_init(&data->update_lock);

 	/* Initialize the LTC4215 chip */
 	i2c_smbus_write_byte_data(client, LTC4215_FAULT, 0x00);

 	hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
 							   data,
 							   ltc4215_groups);
 	return PTR_ERR_OR_ZERO(hwmon_dev);
 }

 static const struct i2c_device_id ltc4215_id[] = {
 	{ "ltc4215", 0 },
 	{ }
 };
 MODULE_DEVICE_TABLE(i2c, ltc4215_id);

 /* This is the driver that will be inserted */
 static struct i2c_driver ltc4215_driver = {
 	.driver = {
 		.name	= "ltc4215",
 	},
 	.probe		= ltc4215_probe,
 	.id_table	= ltc4215_id,
 };

 module_i2c_driver(ltc4215_driver);

 MODULE_AUTHOR("Ira W. Snyder <iws@ovro.caltech.edu>");
 MODULE_DESCRIPTION("LTC4215 driver");
 MODULE_LICENSE("GPL");
	/*
	* Driver for Linear Technology LTC4215 I2C Hot Swap Controller
	*
	* Copyright (C) 2009 Ira W. Snyder <iws@ovro.caltech.edu>
	*
	* 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.
	*
	* Datasheet:
	* http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1003,C1006,C1163,P17572,D12697
	*/

	#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/jiffies.h>

	/* Here are names of the chip's registers (a.k.a. commands) */
	enum ltc4215_cmd {
	LTC4215_CONTROL = 0x00, /* rw */
	LTC4215_ALERT = 0x01, /* rw */
	LTC4215_STATUS = 0x02, /* ro */
	LTC4215_FAULT = 0x03, /* rw */
	LTC4215_SENSE = 0x04, /* rw */
	LTC4215_SOURCE = 0x05, /* rw */
	LTC4215_ADIN = 0x06, /* rw */
	};

	struct ltc4215_data {
	struct i2c_client *client;

	struct mutex update_lock;
	bool valid;
	unsigned long last_updated; /* in jiffies */

	/* Registers */
	u8 regs[7];
	};

	static struct ltc4215_data ltc4215_update_device(struct device dev)
	{
	struct ltc4215_data *data = dev_get_drvdata(dev);
	struct i2c_client *client = data->client;
	s32 val;
	int i;

	mutex_lock(&data->update_lock);

	/* The chip's A/D updates 10 times per second */
	if (time_after(jiffies, data->last_updated + HZ / 10) \|\| !data->valid) {

	dev_dbg(&client->dev, "Starting ltc4215 update\n");

	/* Read all registers */
	for (i = 0; i < ARRAY_SIZE(data->regs); i++) {
	val = i2c_smbus_read_byte_data(client, i);
	if (unlikely(val < 0))
	data->regs[i] = 0;
	else
	data->regs[i] = val;
	}

	data->last_updated = jiffies;
	data->valid = 1;
	}

	mutex_unlock(&data->update_lock);

	return data;
	}

	/* Return the voltage from the given register in millivolts */
	static int ltc4215_get_voltage(struct device *dev, u8 reg)
	{
	struct ltc4215_data *data = ltc4215_update_device(dev);
	const u8 regval = data->regs[reg];
	u32 voltage = 0;

	switch (reg) {
	case LTC4215_SENSE:
	/* 151 uV per increment */
	voltage = regval * 151 / 1000;
	break;
	case LTC4215_SOURCE:
	/* 60.5 mV per increment */
	voltage = regval * 605 / 10;
	break;
	case LTC4215_ADIN:
	/*
	* The ADIN input is divided by 12.5, and has 4.82 mV
	* per increment, so we have the additional multiply
	*/
	voltage = regval * 482 * 125 / 1000;
	break;
	default:
	/* If we get here, the developer messed up */
	WARN_ON_ONCE(1);
	break;
	}

	return voltage;
	}

	/* Return the current from the sense resistor in mA */
	static unsigned int ltc4215_get_current(struct device *dev)
	{
	struct ltc4215_data *data = ltc4215_update_device(dev);

	/*
	* The strange looking conversions that follow are fixed-point
	* math, since we cannot do floating point in the kernel.
	*
	* Step 1: convert sense register to microVolts
	* Step 2: convert voltage to milliAmperes
	*
	* If you play around with the V=IR equation, you come up with
	* the following: X uV / Y mOhm == Z mA
	*
	* With the resistors that are fractions of a milliOhm, we multiply
	* the voltage and resistance by 10, to shift the decimal point.
	* Now we can use the normal division operator again.
	*/

	/* Calculate voltage in microVolts (151 uV per increment) */
	const unsigned int voltage = data->regs[LTC4215_SENSE] * 151;

	/* Calculate current in milliAmperes (4 milliOhm sense resistor) */
	const unsigned int curr = voltage / 4;

	return curr;
	}

	static ssize_t ltc4215_show_voltage(struct device *dev,
	struct device_attribute *da,
	char *buf)
	{
	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
	const int voltage = ltc4215_get_voltage(dev, attr->index);

	return snprintf(buf, PAGE_SIZE, "%d\n", voltage);
	}

	static ssize_t ltc4215_show_current(struct device *dev,
	struct device_attribute *da,
	char *buf)
	{
	const unsigned int curr = ltc4215_get_current(dev);

	return snprintf(buf, PAGE_SIZE, "%u\n", curr);
	}

	static ssize_t ltc4215_show_power(struct device *dev,
	struct device_attribute *da,
	char *buf)
	{
	const unsigned int curr = ltc4215_get_current(dev);
	const int output_voltage = ltc4215_get_voltage(dev, LTC4215_ADIN);

	/* current in mA * voltage in mV == power in uW */
	const unsigned int power = abs(output_voltage * curr);

	return snprintf(buf, PAGE_SIZE, "%u\n", power);
	}

	static ssize_t ltc4215_show_alarm(struct device *dev,
	struct device_attribute *da,
	char *buf)
	{
	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
	struct ltc4215_data *data = ltc4215_update_device(dev);
	const u8 reg = data->regs[LTC4215_STATUS];
	const u32 mask = attr->index;

	return snprintf(buf, PAGE_SIZE, "%u\n", !!(reg & mask));
	}

	/*
	* These macros are used below in constructing device attribute objects
	* for use with sysfs_create_group() to make a sysfs device file
	* for each register.
	*/

	/* Construct a sensor_device_attribute structure for each register */

	/* Current */
	static SENSOR_DEVICE_ATTR(curr1_input, S_IRUGO, ltc4215_show_current, NULL, 0);
	static SENSOR_DEVICE_ATTR(curr1_max_alarm, S_IRUGO, ltc4215_show_alarm, NULL,
	1 << 2);

	/* Power (virtual) */
	static SENSOR_DEVICE_ATTR(power1_input, S_IRUGO, ltc4215_show_power, NULL, 0);

	/* Input Voltage */
	static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, ltc4215_show_voltage, NULL,
	LTC4215_ADIN);
	static SENSOR_DEVICE_ATTR(in1_max_alarm, S_IRUGO, ltc4215_show_alarm, NULL,
	1 << 0);
	static SENSOR_DEVICE_ATTR(in1_min_alarm, S_IRUGO, ltc4215_show_alarm, NULL,
	1 << 1);

	/* Output Voltage */
	static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, ltc4215_show_voltage, NULL,
	LTC4215_SOURCE);
	static SENSOR_DEVICE_ATTR(in2_min_alarm, S_IRUGO, ltc4215_show_alarm, NULL,
	1 << 3);

	/*
	* Finally, construct an array of pointers to members of the above objects,
	* as required for sysfs_create_group()
	*/
	static struct attribute *ltc4215_attrs[] = {
	&sensor_dev_attr_curr1_input.dev_attr.attr,
	&sensor_dev_attr_curr1_max_alarm.dev_attr.attr,

	&sensor_dev_attr_power1_input.dev_attr.attr,

	&sensor_dev_attr_in1_input.dev_attr.attr,
	&sensor_dev_attr_in1_max_alarm.dev_attr.attr,
	&sensor_dev_attr_in1_min_alarm.dev_attr.attr,

	&sensor_dev_attr_in2_input.dev_attr.attr,
	&sensor_dev_attr_in2_min_alarm.dev_attr.attr,

	NULL,
	};
	ATTRIBUTE_GROUPS(ltc4215);

	static int ltc4215_probe(struct i2c_client *client,
	const struct i2c_device_id *id)
	{
	struct i2c_adapter *adapter = client->adapter;
	struct device *dev = &client->dev;
	struct ltc4215_data *data;
	struct device *hwmon_dev;

	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
	return -ENODEV;

	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
	if (!data)
	return -ENOMEM;

	data->client = client;
	mutex_init(&data->update_lock);

	/* Initialize the LTC4215 chip */
	i2c_smbus_write_byte_data(client, LTC4215_FAULT, 0x00);

	hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
	data,
	ltc4215_groups);
	return PTR_ERR_OR_ZERO(hwmon_dev);
	}

	static const struct i2c_device_id ltc4215_id[] = {
	{ "ltc4215", 0 },
	{ }
	};
	MODULE_DEVICE_TABLE(i2c, ltc4215_id);

	/* This is the driver that will be inserted */
	static struct i2c_driver ltc4215_driver = {
	.driver = {
	.name = "ltc4215",
	},
	.probe = ltc4215_probe,
	.id_table = ltc4215_id,
	};

	module_i2c_driver(ltc4215_driver);

	MODULE_AUTHOR("Ira W. Snyder <iws@ovro.caltech.edu>");
	MODULE_DESCRIPTION("LTC4215 driver");
	MODULE_LICENSE("GPL");