summaryrefslogtreecommitdiffstats
path: root/drivers/hwmon/lm75.c
blob: fa7696905154ca1e14444ca2a95e946470084cd4 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
/*
    lm75.c - Part of lm_sensors, Linux kernel modules for hardware
             monitoring
    Copyright (c) 1998, 1999  Frodo Looijaard <frodol@dds.nl>

    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/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/jiffies.h>
#include <linux/i2c.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/err.h>
#include <linux/mutex.h>
#include "lm75.h"


/* Addresses to scan */
static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b, 0x4c,
					0x4d, 0x4e, 0x4f, I2C_CLIENT_END };

/* Insmod parameters */
I2C_CLIENT_INSMOD_1(lm75);

/* Many LM75 constants specified below */

/* The LM75 registers */
#define LM75_REG_CONF		0x01
static const u8 LM75_REG_TEMP[3] = {
	0x00,		/* input */
	0x03,		/* max */
	0x02,		/* hyst */
};

/* Each client has this additional data */
struct lm75_data {
	struct i2c_client	client;
	struct device *hwmon_dev;
	struct mutex		update_lock;
	char			valid;		/* !=0 if following fields are valid */
	unsigned long		last_updated;	/* In jiffies */
	u16			temp[3];	/* Register values,
						   0 = input
						   1 = max
						   2 = hyst */
};

static int lm75_attach_adapter(struct i2c_adapter *adapter);
static int lm75_detect(struct i2c_adapter *adapter, int address, int kind);
static void lm75_init_client(struct i2c_client *client);
static int lm75_detach_client(struct i2c_client *client);
static int lm75_read_value(struct i2c_client *client, u8 reg);
static int lm75_write_value(struct i2c_client *client, u8 reg, u16 value);
static struct lm75_data *lm75_update_device(struct device *dev);


/* This is the driver that will be inserted */
static struct i2c_driver lm75_driver = {
	.driver = {
		.name	= "lm75",
	},
	.attach_adapter	= lm75_attach_adapter,
	.detach_client	= lm75_detach_client,
};

static ssize_t show_temp(struct device *dev, struct device_attribute *da,
			 char *buf)
{
	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
	struct lm75_data *data = lm75_update_device(dev);
	return sprintf(buf, "%d\n",
		       LM75_TEMP_FROM_REG(data->temp[attr->index]));
}

static ssize_t set_temp(struct device *dev, struct device_attribute *da,
			const char *buf, size_t count)
{
	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
	struct i2c_client *client = to_i2c_client(dev);
	struct lm75_data *data = i2c_get_clientdata(client);
	int nr = attr->index;
	long temp = simple_strtol(buf, NULL, 10);

	mutex_lock(&data->update_lock);
	data->temp[nr] = LM75_TEMP_TO_REG(temp);
	lm75_write_value(client, LM75_REG_TEMP[nr], data->temp[nr]);
	mutex_unlock(&data->update_lock);
	return count;
}

static SENSOR_DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO,
			show_temp, set_temp, 1);
static SENSOR_DEVICE_ATTR(temp1_max_hyst, S_IWUSR | S_IRUGO,
			show_temp, set_temp, 2);
static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_temp, NULL, 0);

static int lm75_attach_adapter(struct i2c_adapter *adapter)
{
	if (!(adapter->class & I2C_CLASS_HWMON))
		return 0;
	return i2c_probe(adapter, &addr_data, lm75_detect);
}

static struct attribute *lm75_attributes[] = {
	&sensor_dev_attr_temp1_input.dev_attr.attr,
	&sensor_dev_attr_temp1_max.dev_attr.attr,
	&sensor_dev_attr_temp1_max_hyst.dev_attr.attr,

	NULL
};

static const struct attribute_group lm75_group = {
	.attrs = lm75_attributes,
};

/* This function is called by i2c_probe */
static int lm75_detect(struct i2c_adapter *adapter, int address, int kind)
{
	int i;
	struct i2c_client *new_client;
	struct lm75_data *data;
	int err = 0;
	const char *name = "";

	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
				     I2C_FUNC_SMBUS_WORD_DATA))
		goto exit;

	/* OK. For now, we presume we have a valid client. We now create the
	   client structure, even though we cannot fill it completely yet.
	   But it allows us to access lm75_{read,write}_value. */
	if (!(data = kzalloc(sizeof(struct lm75_data), GFP_KERNEL))) {
		err = -ENOMEM;
		goto exit;
	}

	new_client = &data->client;
	i2c_set_clientdata(new_client, data);
	new_client->addr = address;
	new_client->adapter = adapter;
	new_client->driver = &lm75_driver;
	new_client->flags = 0;

	/* Now, we do the remaining detection. There is no identification-
	   dedicated register so we have to rely on several tricks:
	   unused bits, registers cycling over 8-address boundaries,
	   addresses 0x04-0x07 returning the last read value.
	   The cycling+unused addresses combination is not tested,
	   since it would significantly slow the detection down and would
	   hardly add any value. */
	if (kind < 0) {
		int cur, conf, hyst, os;

		/* Unused addresses */
		cur = i2c_smbus_read_word_data(new_client, 0);
		conf = i2c_smbus_read_byte_data(new_client, 1);
		hyst = i2c_smbus_read_word_data(new_client, 2);
		if (i2c_smbus_read_word_data(new_client, 4) != hyst
		 || i2c_smbus_read_word_data(new_client, 5) != hyst
		 || i2c_smbus_read_word_data(new_client, 6) != hyst
		 || i2c_smbus_read_word_data(new_client, 7) != hyst)
		 	goto exit_free;
		os = i2c_smbus_read_word_data(new_client, 3);
		if (i2c_smbus_read_word_data(new_client, 4) != os
		 || i2c_smbus_read_word_data(new_client, 5) != os
		 || i2c_smbus_read_word_data(new_client, 6) != os
		 || i2c_smbus_read_word_data(new_client, 7) != os)
		 	goto exit_free;

		/* Unused bits */
		if (conf & 0xe0)
		 	goto exit_free;

		/* Addresses cycling */
		for (i = 8; i < 0xff; i += 8)
			if (i2c_smbus_read_byte_data(new_client, i + 1) != conf
			 || i2c_smbus_read_word_data(new_client, i + 2) != hyst
			 || i2c_smbus_read_word_data(new_client, i + 3) != os)
				goto exit_free;
	}

	/* Determine the chip type - only one kind supported! */
	if (kind <= 0)
		kind = lm75;

	if (kind == lm75) {
		name = "lm75";
	}

	/* Fill in the remaining client fields and put it into the global list */
	strlcpy(new_client->name, name, I2C_NAME_SIZE);
	data->valid = 0;
	mutex_init(&data->update_lock);

	/* Tell the I2C layer a new client has arrived */
	if ((err = i2c_attach_client(new_client)))
		goto exit_free;

	/* Initialize the LM75 chip */
	lm75_init_client(new_client);
	
	/* Register sysfs hooks */
	if ((err = sysfs_create_group(&new_client->dev.kobj, &lm75_group)))
		goto exit_detach;

	data->hwmon_dev = hwmon_device_register(&new_client->dev);
	if (IS_ERR(data->hwmon_dev)) {
		err = PTR_ERR(data->hwmon_dev);
		goto exit_remove;
	}

	return 0;

exit_remove:
	sysfs_remove_group(&new_client->dev.kobj, &lm75_group);
exit_detach:
	i2c_detach_client(new_client);
exit_free:
	kfree(data);
exit:
	return err;
}

static int lm75_detach_client(struct i2c_client *client)
{
	struct lm75_data *data = i2c_get_clientdata(client);
	hwmon_device_unregister(data->hwmon_dev);
	sysfs_remove_group(&client->dev.kobj, &lm75_group);
	i2c_detach_client(client);
	kfree(data);
	return 0;
}

/* All registers are word-sized, except for the configuration register.
   LM75 uses a high-byte first convention, which is exactly opposite to
   the SMBus standard. */
static int lm75_read_value(struct i2c_client *client, u8 reg)
{
	if (reg == LM75_REG_CONF)
		return i2c_smbus_read_byte_data(client, reg);
	else
		return swab16(i2c_smbus_read_word_data(client, reg));
}

static int lm75_write_value(struct i2c_client *client, u8 reg, u16 value)
{
	if (reg == LM75_REG_CONF)
		return i2c_smbus_write_byte_data(client, reg, value);
	else
		return i2c_smbus_write_word_data(client, reg, swab16(value));
}

static void lm75_init_client(struct i2c_client *client)
{
	int reg;

	/* Enable if in shutdown mode */
	reg = lm75_read_value(client, LM75_REG_CONF);
	if (reg >= 0 && (reg & 0x01))
		lm75_write_value(client, LM75_REG_CONF, reg & 0xfe);
}

static struct lm75_data *lm75_update_device(struct device *dev)
{
	struct i2c_client *client = to_i2c_client(dev);
	struct lm75_data *data = i2c_get_clientdata(client);

	mutex_lock(&data->update_lock);

	if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
	    || !data->valid) {
		int i;
		dev_dbg(&client->dev, "Starting lm75 update\n");

		for (i = 0; i < ARRAY_SIZE(data->temp); i++)
			data->temp[i] = lm75_read_value(client,
							LM75_REG_TEMP[i]);
		data->last_updated = jiffies;
		data->valid = 1;
	}

	mutex_unlock(&data->update_lock);

	return data;
}

static int __init sensors_lm75_init(void)
{
	return i2c_add_driver(&lm75_driver);
}

static void __exit sensors_lm75_exit(void)
{
	i2c_del_driver(&lm75_driver);
}

MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl>");
MODULE_DESCRIPTION("LM75 driver");
MODULE_LICENSE("GPL");

module_init(sensors_lm75_init);
module_exit(sensors_lm75_exit);
OpenPOWER on IntegriCloud