[deliverable/linux.git] / drivers / hwmon / ltc4215.c

/*
 * 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 device *hwmon_dev;

	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 i2c_client *client = to_i2c_client(dev);
	struct ltc4215_data *data = i2c_get_clientdata(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_attributes[] = {
	&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,
};

static const struct attribute_group ltc4215_group = {
	.attrs = ltc4215_attributes,
};

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

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

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

	i2c_set_clientdata(client, data);
	mutex_init(&data->update_lock);

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

	/* Register sysfs hooks */
	ret = sysfs_create_group(&client->dev.kobj, &ltc4215_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_hwmon_device_register;
	}

	return 0;

out_hwmon_device_register:
	sysfs_remove_group(&client->dev.kobj, &ltc4215_group);
	return ret;
}

static int ltc4215_remove(struct i2c_client *client)
{
	struct ltc4215_data *data = i2c_get_clientdata(client);

	hwmon_device_unregister(data->hwmon_dev);
	sysfs_remove_group(&client->dev.kobj, &ltc4215_group);

	return 0;
}

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,
	.remove		= ltc4215_remove,
	.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");
Commit	Line	Data
72f5de92 IS	1	/*
	2	* Driver for Linear Technology LTC4215 I2C Hot Swap Controller
	3	*
	4	* Copyright (C) 2009 Ira W. Snyder <iws@ovro.caltech.edu>
	5	*
	6	* This program is free software; you can redistribute it and/or modify
	7	* it under the terms of the GNU General Public License as published by
	8	* the Free Software Foundation; version 2 of the License.
	9	*
	10	* Datasheet:
	11	* http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1003,C1006,C1163,P17572,D12697
	12	*/
	13
	14	#include <linux/kernel.h>
	15	#include <linux/module.h>
	16	#include <linux/init.h>
	17	#include <linux/err.h>
	18	#include <linux/slab.h>
	19	#include <linux/i2c.h>
	20	#include <linux/hwmon.h>
	21	#include <linux/hwmon-sysfs.h>
dcd8f392	22	#include <linux/jiffies.h>
72f5de92	23
72f5de92 IS	24	/* Here are names of the chip's registers (a.k.a. commands) */
	25	enum ltc4215_cmd {
	26	LTC4215_CONTROL = 0x00, /* rw */
	27	LTC4215_ALERT = 0x01, /* rw */
	28	LTC4215_STATUS = 0x02, /* ro */
	29	LTC4215_FAULT = 0x03, /* rw */
	30	LTC4215_SENSE = 0x04, /* rw */
	31	LTC4215_SOURCE = 0x05, /* rw */
	32	LTC4215_ADIN = 0x06, /* rw */
	33	};
	34
	35	struct ltc4215_data {
	36	struct device *hwmon_dev;
	37
	38	struct mutex update_lock;
	39	bool valid;
	40	unsigned long last_updated; /* in jiffies */
	41
	42	/* Registers */
	43	u8 regs[7];
	44	};
	45
	46	static struct ltc4215_data ltc4215_update_device(struct device dev)
	47	{
	48	struct i2c_client *client = to_i2c_client(dev);
	49	struct ltc4215_data *data = i2c_get_clientdata(client);
	50	s32 val;
	51	int i;
	52
	53	mutex_lock(&data->update_lock);
	54
	55	/* The chip's A/D updates 10 times per second */
	56	if (time_after(jiffies, data->last_updated + HZ / 10) \|\| !data->valid) {
	57
	58	dev_dbg(&client->dev, "Starting ltc4215 update\n");
	59
	60	/* Read all registers */
	61	for (i = 0; i < ARRAY_SIZE(data->regs); i++) {
	62	val = i2c_smbus_read_byte_data(client, i);
	63	if (unlikely(val < 0))
	64	data->regs[i] = 0;
	65	else
	66	data->regs[i] = val;
	67	}
	68
	69	data->last_updated = jiffies;
	70	data->valid = 1;
	71	}
	72
	73	mutex_unlock(&data->update_lock);
	74
	75	return data;
	76	}
	77
	78	/* Return the voltage from the given register in millivolts */
	79	static int ltc4215_get_voltage(struct device *dev, u8 reg)
	80	{
	81	struct ltc4215_data *data = ltc4215_update_device(dev);
	82	const u8 regval = data->regs[reg];
	83	u32 voltage = 0;
	84
	85	switch (reg) {
	86	case LTC4215_SENSE:
	87	/* 151 uV per increment */
88	voltage = regval * 151 / 1000;
89	break;
90	case LTC4215_SOURCE:
91	/* 60.5 mV per increment */
92	voltage = regval * 605 / 10;
93	break;
94	case LTC4215_ADIN:
790fa38c GR	95	/*
	96	* The ADIN input is divided by 12.5, and has 4.82 mV
	97	* per increment, so we have the additional multiply
	98	*/
72f5de92 IS	99	voltage = regval * 482 * 125 / 1000;
	100	break;
	101	default:
	102	/* If we get here, the developer messed up */
	103	WARN_ON_ONCE(1);
	104	break;
	105	}
	106
	107	return voltage;
	108	}
	109
	110	/* Return the current from the sense resistor in mA */
	111	static unsigned int ltc4215_get_current(struct device *dev)
	112	{
	113	struct ltc4215_data *data = ltc4215_update_device(dev);
	114
790fa38c GR	115	/*
790fa38c GR	116	* The strange looking conversions that follow are fixed-point
72f5de92 IS	117	* math, since we cannot do floating point in the kernel.
	118	*
	119	* Step 1: convert sense register to microVolts
	120	* Step 2: convert voltage to milliAmperes
	121	*
	122	* If you play around with the V=IR equation, you come up with
	123	* the following: X uV / Y mOhm == Z mA
	124	*
	125	* With the resistors that are fractions of a milliOhm, we multiply
	126	* the voltage and resistance by 10, to shift the decimal point.
	127	* Now we can use the normal division operator again.
	128	*/
	129
	130	/* Calculate voltage in microVolts (151 uV per increment) */
	131	const unsigned int voltage = data->regs[LTC4215_SENSE] * 151;
	132
	133	/* Calculate current in milliAmperes (4 milliOhm sense resistor) */
	134	const unsigned int curr = voltage / 4;
	135
	136	return curr;
	137	}
	138
	139	static ssize_t ltc4215_show_voltage(struct device *dev,
	140	struct device_attribute *da,
	141	char *buf)
	142	{
	143	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
	144	const int voltage = ltc4215_get_voltage(dev, attr->index);
	145
	146	return snprintf(buf, PAGE_SIZE, "%d\n", voltage);
	147	}
	148
	149	static ssize_t ltc4215_show_current(struct device *dev,
	150	struct device_attribute *da,
	151	char *buf)
	152	{
	153	const unsigned int curr = ltc4215_get_current(dev);
	154
	155	return snprintf(buf, PAGE_SIZE, "%u\n", curr);
	156	}
	157
	158	static ssize_t ltc4215_show_power(struct device *dev,
	159	struct device_attribute *da,
	160	char *buf)
	161	{
	162	const unsigned int curr = ltc4215_get_current(dev);
	163	const int output_voltage = ltc4215_get_voltage(dev, LTC4215_ADIN);
	164
	165	/* current in mA * voltage in mV == power in uW */
	166	const unsigned int power = abs(output_voltage * curr);
	167
	168	return snprintf(buf, PAGE_SIZE, "%u\n", power);
	169	}
	170
	171	static ssize_t ltc4215_show_alarm(struct device *dev,
	172	struct device_attribute *da,
	173	char *buf)
	174	{
b5f0f1ea	175	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
72f5de92	176	struct ltc4215_data *data = ltc4215_update_device(dev);
b5f0f1ea GR	177	const u8 reg = data->regs[LTC4215_STATUS];
b5f0f1ea GR	178	const u32 mask = attr->index;
72f5de92	179
b5f0f1ea	180	return snprintf(buf, PAGE_SIZE, "%u\n", !!(reg & mask));
72f5de92 IS	181	}
72f5de92 IS	182
790fa38c GR	183	/*
790fa38c GR	184	* These macros are used below in constructing device attribute objects
72f5de92 IS	185	* for use with sysfs_create_group() to make a sysfs device file
	186	* for each register.
	187	*/
	188
72f5de92 IS	189	/* Construct a sensor_device_attribute structure for each register */
	190
	191	/* Current */
b5f0f1ea GR	192	static SENSOR_DEVICE_ATTR(curr1_input, S_IRUGO, ltc4215_show_current, NULL, 0);
	193	static SENSOR_DEVICE_ATTR(curr1_max_alarm, S_IRUGO, ltc4215_show_alarm, NULL,
	194	1 << 2);
72f5de92 IS	195
72f5de92 IS	196	/* Power (virtual) */
b5f0f1ea	197	static SENSOR_DEVICE_ATTR(power1_input, S_IRUGO, ltc4215_show_power, NULL, 0);
72f5de92 IS	198
72f5de92 IS	199	/* Input Voltage */
b5f0f1ea GR	200	static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, ltc4215_show_voltage, NULL,
	201	LTC4215_ADIN);
	202	static SENSOR_DEVICE_ATTR(in1_max_alarm, S_IRUGO, ltc4215_show_alarm, NULL,
	203	1 << 0);
	204	static SENSOR_DEVICE_ATTR(in1_min_alarm, S_IRUGO, ltc4215_show_alarm, NULL,
	205	1 << 1);
72f5de92 IS	206
72f5de92 IS	207	/* Output Voltage */
b5f0f1ea GR	208	static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, ltc4215_show_voltage, NULL,
	209	LTC4215_SOURCE);
	210	static SENSOR_DEVICE_ATTR(in2_min_alarm, S_IRUGO, ltc4215_show_alarm, NULL,
	211	1 << 3);
72f5de92	212
790fa38c GR	213	/*
790fa38c GR	214	* Finally, construct an array of pointers to members of the above objects,
72f5de92 IS	215	* as required for sysfs_create_group()
	216	*/
	217	static struct attribute *ltc4215_attributes[] = {
	218	&sensor_dev_attr_curr1_input.dev_attr.attr,
	219	&sensor_dev_attr_curr1_max_alarm.dev_attr.attr,
	220
	221	&sensor_dev_attr_power1_input.dev_attr.attr,
72f5de92 IS	222
	223	&sensor_dev_attr_in1_input.dev_attr.attr,
	224	&sensor_dev_attr_in1_max_alarm.dev_attr.attr,
	225	&sensor_dev_attr_in1_min_alarm.dev_attr.attr,
	226
	227	&sensor_dev_attr_in2_input.dev_attr.attr,
0a6bf658	228	&sensor_dev_attr_in2_min_alarm.dev_attr.attr,
72f5de92 IS	229
	230	NULL,
	231	};
	232
	233	static const struct attribute_group ltc4215_group = {
	234	.attrs = ltc4215_attributes,
	235	};
	236
	237	static int ltc4215_probe(struct i2c_client *client,
	238	const struct i2c_device_id *id)
	239	{
2d2a7cff	240	struct i2c_adapter *adapter = client->adapter;
72f5de92 IS	241	struct ltc4215_data *data;
	242	int ret;
	243
2d2a7cff JD	244	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
	245	return -ENODEV;
	246
d2b95e58 GR	247	data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL);
	248	if (!data)
	249	return -ENOMEM;
72f5de92 IS	250
	251	i2c_set_clientdata(client, data);
	252	mutex_init(&data->update_lock);
	253
	254	/* Initialize the LTC4215 chip */
b6b9d696	255	i2c_smbus_write_byte_data(client, LTC4215_FAULT, 0x00);
72f5de92 IS	256
	257	/* Register sysfs hooks */
	258	ret = sysfs_create_group(&client->dev.kobj, &ltc4215_group);
	259	if (ret)
d2b95e58	260	return ret;
72f5de92 IS	261
	262	data->hwmon_dev = hwmon_device_register(&client->dev);
	263	if (IS_ERR(data->hwmon_dev)) {
	264	ret = PTR_ERR(data->hwmon_dev);
	265	goto out_hwmon_device_register;
	266	}
	267
	268	return 0;
	269
	270	out_hwmon_device_register:
	271	sysfs_remove_group(&client->dev.kobj, &ltc4215_group);
72f5de92 IS	272	return ret;
	273	}
	274
	275	static int ltc4215_remove(struct i2c_client *client)
	276	{
	277	struct ltc4215_data *data = i2c_get_clientdata(client);
	278
	279	hwmon_device_unregister(data->hwmon_dev);
	280	sysfs_remove_group(&client->dev.kobj, &ltc4215_group);
	281
72f5de92 IS	282	return 0;
	283	}
	284
72f5de92	285	static const struct i2c_device_id ltc4215_id[] = {
2d2a7cff	286	{ "ltc4215", 0 },
72f5de92 IS	287	{ }
	288	};
	289	MODULE_DEVICE_TABLE(i2c, ltc4215_id);
	290
	291	/* This is the driver that will be inserted */
	292	static struct i2c_driver ltc4215_driver = {
72f5de92 IS	293	.driver = {
	294	.name = "ltc4215",
	295	},
	296	.probe = ltc4215_probe,
	297	.remove = ltc4215_remove,
	298	.id_table = ltc4215_id,
72f5de92 IS	299	};
72f5de92 IS	300
f0967eea	301	module_i2c_driver(ltc4215_driver);
72f5de92 IS	302
	303	MODULE_AUTHOR("Ira W. Snyder <iws@ovro.caltech.edu>");
	304	MODULE_DESCRIPTION("LTC4215 driver");
	305	MODULE_LICENSE("GPL");