1/*
2    lm75.c - Part of lm_sensors, Linux kernel modules for hardware
3             monitoring
4    Copyright (c) 1998, 1999  Frodo Looijaard <frodol@dds.nl>
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; either version 2 of the License, or
9    (at your option) any later version.
10
11    This program is distributed in the hope that it will be useful,
12    but WITHOUT ANY WARRANTY; without even the implied warranty of
13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14    GNU General Public License for more details.
15
16    You should have received a copy of the GNU General Public License
17    along with this program; if not, write to the Free Software
18    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
19*/
20
21#include <linux/module.h>
22#include <linux/init.h>
23#include <linux/slab.h>
24#include <linux/jiffies.h>
25#include <linux/i2c.h>
26#include <linux/hwmon.h>
27#include <linux/hwmon-sysfs.h>
28#include <linux/err.h>
29#include <linux/mutex.h>
30#include "lm75.h"
31
32
33/* Addresses to scan */
34static unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b, 0x4c,
35					0x4d, 0x4e, 0x4f, I2C_CLIENT_END };
36
37/* Insmod parameters */
38I2C_CLIENT_INSMOD_1(lm75);
39
40/* Many LM75 constants specified below */
41
42/* The LM75 registers */
43#define LM75_REG_CONF		0x01
44static const u8 LM75_REG_TEMP[3] = {
45	0x00,		/* input */
46	0x03,		/* max */
47	0x02,		/* hyst */
48};
49
50/* Each client has this additional data */
51struct lm75_data {
52	struct i2c_client	client;
53	struct class_device *class_dev;
54	struct mutex		update_lock;
55	char			valid;		/* !=0 if following fields are valid */
56	unsigned long		last_updated;	/* In jiffies */
57	u16			temp[3];	/* Register values,
58						   0 = input
59						   1 = max
60						   2 = hyst */
61};
62
63static int lm75_attach_adapter(struct i2c_adapter *adapter);
64static int lm75_detect(struct i2c_adapter *adapter, int address, int kind);
65static void lm75_init_client(struct i2c_client *client);
66static int lm75_detach_client(struct i2c_client *client);
67static int lm75_read_value(struct i2c_client *client, u8 reg);
68static int lm75_write_value(struct i2c_client *client, u8 reg, u16 value);
69static struct lm75_data *lm75_update_device(struct device *dev);
70
71
72/* This is the driver that will be inserted */
73static struct i2c_driver lm75_driver = {
74	.driver = {
75		.name	= "lm75",
76	},
77	.id		= I2C_DRIVERID_LM75,
78	.attach_adapter	= lm75_attach_adapter,
79	.detach_client	= lm75_detach_client,
80};
81
82static ssize_t show_temp(struct device *dev, struct device_attribute *da,
83			 char *buf)
84{
85	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
86	struct lm75_data *data = lm75_update_device(dev);
87	return sprintf(buf, "%d\n",
88		       LM75_TEMP_FROM_REG(data->temp[attr->index]));
89}
90
91static ssize_t set_temp(struct device *dev, struct device_attribute *da,
92			const char *buf, size_t count)
93{
94	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
95	struct i2c_client *client = to_i2c_client(dev);
96	struct lm75_data *data = i2c_get_clientdata(client);
97	int nr = attr->index;
98	unsigned long temp = simple_strtoul(buf, NULL, 10);
99
100	mutex_lock(&data->update_lock);
101	data->temp[nr] = LM75_TEMP_TO_REG(temp);
102	lm75_write_value(client, LM75_REG_TEMP[nr], data->temp[nr]);
103	mutex_unlock(&data->update_lock);
104	return count;
105}
106
107static SENSOR_DEVICE_ATTR(temp1_max, S_IWUSR | S_IRUGO,
108			show_temp, set_temp, 1);
109static SENSOR_DEVICE_ATTR(temp1_max_hyst, S_IWUSR | S_IRUGO,
110			show_temp, set_temp, 2);
111static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_temp, NULL, 0);
112
113static int lm75_attach_adapter(struct i2c_adapter *adapter)
114{
115	if (!(adapter->class & I2C_CLASS_HWMON))
116		return 0;
117	return i2c_probe(adapter, &addr_data, lm75_detect);
118}
119
120static struct attribute *lm75_attributes[] = {
121	&sensor_dev_attr_temp1_input.dev_attr.attr,
122	&sensor_dev_attr_temp1_max.dev_attr.attr,
123	&sensor_dev_attr_temp1_max_hyst.dev_attr.attr,
124
125	NULL
126};
127
128static const struct attribute_group lm75_group = {
129	.attrs = lm75_attributes,
130};
131
132/* This function is called by i2c_probe */
133static int lm75_detect(struct i2c_adapter *adapter, int address, int kind)
134{
135	int i;
136	struct i2c_client *new_client;
137	struct lm75_data *data;
138	int err = 0;
139	const char *name = "";
140
141	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
142				     I2C_FUNC_SMBUS_WORD_DATA))
143		goto exit;
144
145	/* OK. For now, we presume we have a valid client. We now create the
146	   client structure, even though we cannot fill it completely yet.
147	   But it allows us to access lm75_{read,write}_value. */
148	if (!(data = kzalloc(sizeof(struct lm75_data), GFP_KERNEL))) {
149		err = -ENOMEM;
150		goto exit;
151	}
152
153	new_client = &data->client;
154	i2c_set_clientdata(new_client, data);
155	new_client->addr = address;
156	new_client->adapter = adapter;
157	new_client->driver = &lm75_driver;
158	new_client->flags = 0;
159
160	/* Now, we do the remaining detection. There is no identification-
161	   dedicated register so we have to rely on several tricks:
162	   unused bits, registers cycling over 8-address boundaries,
163	   addresses 0x04-0x07 returning the last read value.
164	   The cycling+unused addresses combination is not tested,
165	   since it would significantly slow the detection down and would
166	   hardly add any value. */
167	if (kind < 0) {
168		int cur, conf, hyst, os;
169
170		/* Unused addresses */
171		cur = i2c_smbus_read_word_data(new_client, 0);
172		conf = i2c_smbus_read_byte_data(new_client, 1);
173		hyst = i2c_smbus_read_word_data(new_client, 2);
174		if (i2c_smbus_read_word_data(new_client, 4) != hyst
175		 || i2c_smbus_read_word_data(new_client, 5) != hyst
176		 || i2c_smbus_read_word_data(new_client, 6) != hyst
177		 || i2c_smbus_read_word_data(new_client, 7) != hyst)
178		 	goto exit_free;
179		os = i2c_smbus_read_word_data(new_client, 3);
180		if (i2c_smbus_read_word_data(new_client, 4) != os
181		 || i2c_smbus_read_word_data(new_client, 5) != os
182		 || i2c_smbus_read_word_data(new_client, 6) != os
183		 || i2c_smbus_read_word_data(new_client, 7) != os)
184		 	goto exit_free;
185
186		/* Unused bits */
187		if (conf & 0xe0)
188		 	goto exit_free;
189
190		/* Addresses cycling */
191		for (i = 8; i < 0xff; i += 8)
192			if (i2c_smbus_read_byte_data(new_client, i + 1) != conf
193			 || i2c_smbus_read_word_data(new_client, i + 2) != hyst
194			 || i2c_smbus_read_word_data(new_client, i + 3) != os)
195				goto exit_free;
196	}
197
198	/* Determine the chip type - only one kind supported! */
199	if (kind <= 0)
200		kind = lm75;
201
202	if (kind == lm75) {
203		name = "lm75";
204	}
205
206	/* Fill in the remaining client fields and put it into the global list */
207	strlcpy(new_client->name, name, I2C_NAME_SIZE);
208	data->valid = 0;
209	mutex_init(&data->update_lock);
210
211	/* Tell the I2C layer a new client has arrived */
212	if ((err = i2c_attach_client(new_client)))
213		goto exit_free;
214
215	/* Initialize the LM75 chip */
216	lm75_init_client(new_client);
217
218	/* Register sysfs hooks */
219	if ((err = sysfs_create_group(&new_client->dev.kobj, &lm75_group)))
220		goto exit_detach;
221
222	data->class_dev = hwmon_device_register(&new_client->dev);
223	if (IS_ERR(data->class_dev)) {
224		err = PTR_ERR(data->class_dev);
225		goto exit_remove;
226	}
227
228	return 0;
229
230exit_remove:
231	sysfs_remove_group(&new_client->dev.kobj, &lm75_group);
232exit_detach:
233	i2c_detach_client(new_client);
234exit_free:
235	kfree(data);
236exit:
237	return err;
238}
239
240static int lm75_detach_client(struct i2c_client *client)
241{
242	struct lm75_data *data = i2c_get_clientdata(client);
243	hwmon_device_unregister(data->class_dev);
244	sysfs_remove_group(&client->dev.kobj, &lm75_group);
245	i2c_detach_client(client);
246	kfree(data);
247	return 0;
248}
249
250/* All registers are word-sized, except for the configuration register.
251   LM75 uses a high-byte first convention, which is exactly opposite to
252   the usual practice. */
253static int lm75_read_value(struct i2c_client *client, u8 reg)
254{
255	if (reg == LM75_REG_CONF)
256		return i2c_smbus_read_byte_data(client, reg);
257	else
258		return swab16(i2c_smbus_read_word_data(client, reg));
259}
260
261/* All registers are word-sized, except for the configuration register.
262   LM75 uses a high-byte first convention, which is exactly opposite to
263   the usual practice. */
264static int lm75_write_value(struct i2c_client *client, u8 reg, u16 value)
265{
266	if (reg == LM75_REG_CONF)
267		return i2c_smbus_write_byte_data(client, reg, value);
268	else
269		return i2c_smbus_write_word_data(client, reg, swab16(value));
270}
271
272static void lm75_init_client(struct i2c_client *client)
273{
274	int reg;
275
276	/* Enable if in shutdown mode */
277	reg = lm75_read_value(client, LM75_REG_CONF);
278	if (reg >= 0 && (reg & 0x01))
279		lm75_write_value(client, LM75_REG_CONF, reg & 0xfe);
280}
281
282static struct lm75_data *lm75_update_device(struct device *dev)
283{
284	struct i2c_client *client = to_i2c_client(dev);
285	struct lm75_data *data = i2c_get_clientdata(client);
286
287	mutex_lock(&data->update_lock);
288
289	if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
290	    || !data->valid) {
291		int i;
292		dev_dbg(&client->dev, "Starting lm75 update\n");
293
294		for (i = 0; i < ARRAY_SIZE(data->temp); i++)
295			data->temp[i] = lm75_read_value(client,
296							LM75_REG_TEMP[i]);
297		data->last_updated = jiffies;
298		data->valid = 1;
299	}
300
301	mutex_unlock(&data->update_lock);
302
303	return data;
304}
305
306static int __init sensors_lm75_init(void)
307{
308	return i2c_add_driver(&lm75_driver);
309}
310
311static void __exit sensors_lm75_exit(void)
312{
313	i2c_del_driver(&lm75_driver);
314}
315
316MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl>");
317MODULE_DESCRIPTION("LM75 driver");
318MODULE_LICENSE("GPL");
319
320module_init(sensors_lm75_init);
321module_exit(sensors_lm75_exit);
322