[net-next-2.6.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>

/* 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_2 *attr = to_sensor_dev_attr_2(da);
	struct ltc4215_data *data = ltc4215_update_device(dev);
	const u8 reg = data->regs[attr->index];
	const u32 mask = attr->nr;

	return snprintf(buf, PAGE_SIZE, "%u\n", (reg & mask) ? 1 : 0);
}

/* 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.
 */

#define LTC4215_VOLTAGE(name, ltc4215_cmd_idx) \
	static SENSOR_DEVICE_ATTR(name, S_IRUGO, \
	ltc4215_show_voltage, NULL, ltc4215_cmd_idx)

#define LTC4215_CURRENT(name) \
	static SENSOR_DEVICE_ATTR(name, S_IRUGO, \
	ltc4215_show_current, NULL, 0);

#define LTC4215_POWER(name) \
	static SENSOR_DEVICE_ATTR(name, S_IRUGO, \
	ltc4215_show_power, NULL, 0);

#define LTC4215_ALARM(name, mask, reg) \
	static SENSOR_DEVICE_ATTR_2(name, S_IRUGO, \
	ltc4215_show_alarm, NULL, (mask), reg)

/* Construct a sensor_device_attribute structure for each register */

/* Current */
LTC4215_CURRENT(curr1_input);
LTC4215_ALARM(curr1_max_alarm,	(1 << 2),	LTC4215_STATUS);

/* Power (virtual) */
LTC4215_POWER(power1_input);
LTC4215_ALARM(power1_alarm,	(1 << 3),	LTC4215_STATUS);

/* Input Voltage */
LTC4215_VOLTAGE(in1_input,			LTC4215_ADIN);
LTC4215_ALARM(in1_max_alarm,	(1 << 0),	LTC4215_STATUS);
LTC4215_ALARM(in1_min_alarm,	(1 << 1),	LTC4215_STATUS);

/* Output Voltage */
LTC4215_VOLTAGE(in2_input,			LTC4215_SOURCE);

/* 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_power1_alarm.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,

	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 = kzalloc(sizeof(*data), GFP_KERNEL);
	if (!data) {
		ret = -ENOMEM;
		goto out_kzalloc;
	}

	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)
		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, &ltc4215_group);
out_sysfs_create_group:
	kfree(data);
out_kzalloc:
	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);

	kfree(data);

	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,
};

static int __init ltc4215_init(void)
{
	return i2c_add_driver(&ltc4215_driver);
}

static void __exit ltc4215_exit(void)
{
	i2c_del_driver(&ltc4215_driver);
}

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

module_init(ltc4215_init);
module_exit(ltc4215_exit);
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>
	22
72f5de92 IS	23	/* Here are names of the chip's registers (a.k.a. commands) */
	24	enum ltc4215_cmd {
	25	LTC4215_CONTROL = 0x00, /* rw */
	26	LTC4215_ALERT = 0x01, /* rw */
	27	LTC4215_STATUS = 0x02, /* ro */
	28	LTC4215_FAULT = 0x03, /* rw */
	29	LTC4215_SENSE = 0x04, /* rw */
	30	LTC4215_SOURCE = 0x05, /* rw */
	31	LTC4215_ADIN = 0x06, /* rw */
	32	};
	33
	34	struct ltc4215_data {
	35	struct device *hwmon_dev;
	36
	37	struct mutex update_lock;
	38	bool valid;
	39	unsigned long last_updated; /* in jiffies */
	40
	41	/* Registers */
	42	u8 regs[7];
	43	};
	44
	45	static struct ltc4215_data ltc4215_update_device(struct device dev)
	46	{
	47	struct i2c_client *client = to_i2c_client(dev);
	48	struct ltc4215_data *data = i2c_get_clientdata(client);
	49	s32 val;
	50	int i;
	51
	52	mutex_lock(&data->update_lock);
	53
	54	/* The chip's A/D updates 10 times per second */
	55	if (time_after(jiffies, data->last_updated + HZ / 10) \|\| !data->valid) {
	56
	57	dev_dbg(&client->dev, "Starting ltc4215 update\n");
	58
	59	/* Read all registers */
	60	for (i = 0; i < ARRAY_SIZE(data->regs); i++) {
	61	val = i2c_smbus_read_byte_data(client, i);
	62	if (unlikely(val < 0))
	63	data->regs[i] = 0;
	64	else
	65	data->regs[i] = val;
	66	}
	67
	68	data->last_updated = jiffies;
	69	data->valid = 1;
	70	}
	71
	72	mutex_unlock(&data->update_lock);
	73
	74	return data;
	75	}
	76
	77	/* Return the voltage from the given register in millivolts */
	78	static int ltc4215_get_voltage(struct device *dev, u8 reg)
	79	{
	80	struct ltc4215_data *data = ltc4215_update_device(dev);
	81	const u8 regval = data->regs[reg];
	82	u32 voltage = 0;
	83
	84	switch (reg) {
	85	case LTC4215_SENSE:
	86	/* 151 uV per increment */
87	voltage = regval * 151 / 1000;
88	break;
89	case LTC4215_SOURCE:
90	/* 60.5 mV per increment */
91	voltage = regval * 605 / 10;
92	break;
93	case LTC4215_ADIN:
94	/* The ADIN input is divided by 12.5, and has 4.82 mV
95	* per increment, so we have the additional multiply */
96	voltage = regval * 482 * 125 / 1000;
97	break;
98	default:
99	/* If we get here, the developer messed up */
100	WARN_ON_ONCE(1);
101	break;
102	}
103
104	return voltage;
105	}
106
107	/* Return the current from the sense resistor in mA */
108	static unsigned int ltc4215_get_current(struct device *dev)
109	{
110	struct ltc4215_data *data = ltc4215_update_device(dev);
111
112	/* The strange looking conversions that follow are fixed-point
113	* math, since we cannot do floating point in the kernel.
114	*
115	* Step 1: convert sense register to microVolts
116	* Step 2: convert voltage to milliAmperes
117	*
118	* If you play around with the V=IR equation, you come up with
119	* the following: X uV / Y mOhm == Z mA
120	*
121	* With the resistors that are fractions of a milliOhm, we multiply
122	* the voltage and resistance by 10, to shift the decimal point.
123	* Now we can use the normal division operator again.
124	*/
125
126	/* Calculate voltage in microVolts (151 uV per increment) */
127	const unsigned int voltage = data->regs[LTC4215_SENSE] * 151;
128
129	/* Calculate current in milliAmperes (4 milliOhm sense resistor) */
130	const unsigned int curr = voltage / 4;
131
132	return curr;
133	}
134
135	static ssize_t ltc4215_show_voltage(struct device *dev,
136	struct device_attribute *da,
137	char *buf)
138	{
139	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
140	const int voltage = ltc4215_get_voltage(dev, attr->index);
141
142	return snprintf(buf, PAGE_SIZE, "%d\n", voltage);
143	}
144
145	static ssize_t ltc4215_show_current(struct device *dev,
146	struct device_attribute *da,
147	char *buf)
148	{
149	const unsigned int curr = ltc4215_get_current(dev);
150
151	return snprintf(buf, PAGE_SIZE, "%u\n", curr);
152	}
153
154	static ssize_t ltc4215_show_power(struct device *dev,
155	struct device_attribute *da,
156	char *buf)
157	{
158	const unsigned int curr = ltc4215_get_current(dev);
159	const int output_voltage = ltc4215_get_voltage(dev, LTC4215_ADIN);
160
161	/* current in mA * voltage in mV == power in uW */
162	const unsigned int power = abs(output_voltage * curr);
163
164	return snprintf(buf, PAGE_SIZE, "%u\n", power);
165	}
166
167	static ssize_t ltc4215_show_alarm(struct device *dev,
168	struct device_attribute *da,
169	char *buf)
170	{
171	struct sensor_device_attribute_2 *attr = to_sensor_dev_attr_2(da);
172	struct ltc4215_data *data = ltc4215_update_device(dev);
173	const u8 reg = data->regs[attr->index];
174	const u32 mask = attr->nr;
175
176	return snprintf(buf, PAGE_SIZE, "%u\n", (reg & mask) ? 1 : 0);
177	}
178
179	/* These macros are used below in constructing device attribute objects
180	* for use with sysfs_create_group() to make a sysfs device file
181	* for each register.
182	*/
183
184	#define LTC4215_VOLTAGE(name, ltc4215_cmd_idx) \
185	static SENSOR_DEVICE_ATTR(name, S_IRUGO, \
186	ltc4215_show_voltage, NULL, ltc4215_cmd_idx)
187
188	#define LTC4215_CURRENT(name) \
189	static SENSOR_DEVICE_ATTR(name, S_IRUGO, \
190	ltc4215_show_current, NULL, 0);
191
192	#define LTC4215_POWER(name) \
193	static SENSOR_DEVICE_ATTR(name, S_IRUGO, \
194	ltc4215_show_power, NULL, 0);
195
196	#define LTC4215_ALARM(name, mask, reg) \
197	static SENSOR_DEVICE_ATTR_2(name, S_IRUGO, \
198	ltc4215_show_alarm, NULL, (mask), reg)
199
200	/* Construct a sensor_device_attribute structure for each register */
201
202	/* Current */
203	LTC4215_CURRENT(curr1_input);
204	LTC4215_ALARM(curr1_max_alarm, (1 << 2), LTC4215_STATUS);
205
206	/* Power (virtual) */
207	LTC4215_POWER(power1_input);
208	LTC4215_ALARM(power1_alarm, (1 << 3), LTC4215_STATUS);
209
210	/* Input Voltage */
211	LTC4215_VOLTAGE(in1_input, LTC4215_ADIN);
212	LTC4215_ALARM(in1_max_alarm, (1 << 0), LTC4215_STATUS);
213	LTC4215_ALARM(in1_min_alarm, (1 << 1), LTC4215_STATUS);
214
215	/* Output Voltage */
216	LTC4215_VOLTAGE(in2_input, LTC4215_SOURCE);
217
218	/* Finally, construct an array of pointers to members of the above objects,
219	* as required for sysfs_create_group()
220	*/
221	static struct attribute *ltc4215_attributes[] = {
222	&sensor_dev_attr_curr1_input.dev_attr.attr,
223	&sensor_dev_attr_curr1_max_alarm.dev_attr.attr,
224
225	&sensor_dev_attr_power1_input.dev_attr.attr,
226	&sensor_dev_attr_power1_alarm.dev_attr.attr,
227
228	&sensor_dev_attr_in1_input.dev_attr.attr,
229	&sensor_dev_attr_in1_max_alarm.dev_attr.attr,
230	&sensor_dev_attr_in1_min_alarm.dev_attr.attr,
231
232	&sensor_dev_attr_in2_input.dev_attr.attr,
233
234	NULL,
235	};
236
237	static const struct attribute_group ltc4215_group = {
238	.attrs = ltc4215_attributes,
239	};
240
241	static int ltc4215_probe(struct i2c_client *client,
242	const struct i2c_device_id *id)
243	{
2d2a7cff	244	struct i2c_adapter *adapter = client->adapter;
72f5de92 IS	245	struct ltc4215_data *data;
	246	int ret;
	247
2d2a7cff JD	248	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
	249	return -ENODEV;
	250
72f5de92 IS	251	data = kzalloc(sizeof(*data), GFP_KERNEL);
	252	if (!data) {
	253	ret = -ENOMEM;
	254	goto out_kzalloc;
	255	}
	256
	257	i2c_set_clientdata(client, data);
	258	mutex_init(&data->update_lock);
	259
	260	/* Initialize the LTC4215 chip */
b6b9d696	261	i2c_smbus_write_byte_data(client, LTC4215_FAULT, 0x00);
72f5de92 IS	262
	263	/* Register sysfs hooks */
	264	ret = sysfs_create_group(&client->dev.kobj, &ltc4215_group);
	265	if (ret)
	266	goto out_sysfs_create_group;
	267
	268	data->hwmon_dev = hwmon_device_register(&client->dev);
	269	if (IS_ERR(data->hwmon_dev)) {
	270	ret = PTR_ERR(data->hwmon_dev);
	271	goto out_hwmon_device_register;
	272	}
	273
	274	return 0;
	275
	276	out_hwmon_device_register:
	277	sysfs_remove_group(&client->dev.kobj, &ltc4215_group);
	278	out_sysfs_create_group:
	279	kfree(data);
	280	out_kzalloc:
	281	return ret;
	282	}
	283
	284	static int ltc4215_remove(struct i2c_client *client)
	285	{
	286	struct ltc4215_data *data = i2c_get_clientdata(client);
	287
	288	hwmon_device_unregister(data->hwmon_dev);
	289	sysfs_remove_group(&client->dev.kobj, &ltc4215_group);
	290
	291	kfree(data);
	292
	293	return 0;
	294	}
	295
72f5de92	296	static const struct i2c_device_id ltc4215_id[] = {
2d2a7cff	297	{ "ltc4215", 0 },
72f5de92 IS	298	{ }
	299	};
	300	MODULE_DEVICE_TABLE(i2c, ltc4215_id);
	301
	302	/* This is the driver that will be inserted */
	303	static struct i2c_driver ltc4215_driver = {
72f5de92 IS	304	.driver = {
	305	.name = "ltc4215",
	306	},
	307	.probe = ltc4215_probe,
	308	.remove = ltc4215_remove,
	309	.id_table = ltc4215_id,
72f5de92 IS	310	};
	311
	312	static int __init ltc4215_init(void)
	313	{
	314	return i2c_add_driver(&ltc4215_driver);
	315	}
	316
	317	static void __exit ltc4215_exit(void)
	318	{
	319	i2c_del_driver(&ltc4215_driver);
	320	}
	321
	322	MODULE_AUTHOR("Ira W. Snyder <iws@ovro.caltech.edu>");
	323	MODULE_DESCRIPTION("LTC4215 driver");
	324	MODULE_LICENSE("GPL");
	325
	326	module_init(ltc4215_init);
	327	module_exit(ltc4215_exit);