1/*
2 * lm77.c - Part of lm_sensors, Linux kernel modules for hardware
3 * monitoring
4 *
5 * Copyright (c) 2004 Andras BALI <drewie@freemail.hu>
6 *
7 * Heavily based on lm75.c by Frodo Looijaard <frodol@dds.nl>. The LM77
8 * is a temperature sensor and thermal window comparator with 0.5 deg
9 * resolution made by National Semiconductor. Complete datasheet can be
10 * obtained at their site:
11 * http://www.national.com/pf/LM/LM77.html
12 *
13 * This program is free software; you can redistribute it and/or modify
14 * it under the terms of the GNU General Public License as published by
15 * the Free Software Foundation; either version 2 of the License, or
16 * (at your option) any later version.
17 *
18 * This program is distributed in the hope that it will be useful,
19 * but WITHOUT ANY WARRANTY; without even the implied warranty of
20 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
21 * GNU General Public License for more details.
22 */
23
24#include <linux/module.h>
25#include <linux/init.h>
26#include <linux/slab.h>
27#include <linux/jiffies.h>
28#include <linux/i2c.h>
29#include <linux/hwmon.h>
30#include <linux/hwmon-sysfs.h>
31#include <linux/err.h>
32#include <linux/mutex.h>
33
34/* Addresses to scan */
35static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b,
36 I2C_CLIENT_END };
37
38/* The LM77 registers */
39#define LM77_REG_TEMP 0x00
40#define LM77_REG_CONF 0x01
41#define LM77_REG_TEMP_HYST 0x02
42#define LM77_REG_TEMP_CRIT 0x03
43#define LM77_REG_TEMP_MIN 0x04
44#define LM77_REG_TEMP_MAX 0x05
45
46enum temp_index {
47 t_input = 0,
48 t_crit,
49 t_min,
50 t_max,
51 t_hyst,
52 t_num_temp
53};
54
55static const u8 temp_regs[t_num_temp] = {
56 [t_input] = LM77_REG_TEMP,
57 [t_min] = LM77_REG_TEMP_MIN,
58 [t_max] = LM77_REG_TEMP_MAX,
59 [t_crit] = LM77_REG_TEMP_CRIT,
60 [t_hyst] = LM77_REG_TEMP_HYST,
61};
62
63/* Each client has this additional data */
64struct lm77_data {
65 struct i2c_client *client;
66 struct mutex update_lock;
67 char valid;
68 unsigned long last_updated; /* In jiffies */
69 int temp[t_num_temp]; /* index using temp_index */
70 u8 alarms;
71};
72
73/* straight from the datasheet */
74#define LM77_TEMP_MIN (-55000)
75#define LM77_TEMP_MAX 125000
76
77/*
78 * In the temperature registers, the low 3 bits are not part of the
79 * temperature values; they are the status bits.
80 */
81static inline s16 LM77_TEMP_TO_REG(int temp)
82{
83 return (temp / 500) * 8;
84}
85
86static inline int LM77_TEMP_FROM_REG(s16 reg)
87{
88 return (reg / 8) * 500;
89}
90
91/*
92 * All registers are word-sized, except for the configuration register.
93 * The LM77 uses the high-byte first convention.
94 */
95static u16 lm77_read_value(struct i2c_client *client, u8 reg)
96{
97 if (reg == LM77_REG_CONF)
98 return i2c_smbus_read_byte_data(client, reg);
99 else
100 return i2c_smbus_read_word_swapped(client, reg);
101}
102
103static int lm77_write_value(struct i2c_client *client, u8 reg, u16 value)
104{
105 if (reg == LM77_REG_CONF)
106 return i2c_smbus_write_byte_data(client, reg, value);
107 else
108 return i2c_smbus_write_word_swapped(client, reg, value);
109}
110
111static struct lm77_data *lm77_update_device(struct device *dev)
112{
113 struct lm77_data *data = dev_get_drvdata(dev);
114 struct i2c_client *client = data->client;
115 int i;
116
117 mutex_lock(&data->update_lock);
118
119 if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
120 || !data->valid) {
121 dev_dbg(&client->dev, "Starting lm77 update\n");
122 for (i = 0; i < t_num_temp; i++) {
123 data->temp[i] =
124 LM77_TEMP_FROM_REG(lm77_read_value(client,
125 temp_regs[i]));
126 }
127 data->alarms =
128 lm77_read_value(client, LM77_REG_TEMP) & 0x0007;
129 data->last_updated = jiffies;
130 data->valid = 1;
131 }
132
133 mutex_unlock(&data->update_lock);
134
135 return data;
136}
137
138/* sysfs stuff */
139
140static ssize_t temp_show(struct device *dev, struct device_attribute *devattr,
141 char *buf)
142{
143 struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
144 struct lm77_data *data = lm77_update_device(dev);
145
146 return sprintf(buf, "%d\n", data->temp[attr->index]);
147}
148
149static ssize_t temp_hyst_show(struct device *dev,
150 struct device_attribute *devattr, char *buf)
151{
152 struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
153 struct lm77_data *data = lm77_update_device(dev);
154 int nr = attr->index;
155 int temp;
156
157 temp = nr == t_min ? data->temp[nr] + data->temp[t_hyst] :
158 data->temp[nr] - data->temp[t_hyst];
159
160 return sprintf(buf, "%d\n", temp);
161}
162
163static ssize_t temp_store(struct device *dev,
164 struct device_attribute *devattr, const char *buf,
165 size_t count)
166{
167 struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
168 struct lm77_data *data = dev_get_drvdata(dev);
169 struct i2c_client *client = data->client;
170 int nr = attr->index;
171 long val;
172 int err;
173
174 err = kstrtol(buf, 10, &val);
175 if (err)
176 return err;
177
178 val = clamp_val(val, LM77_TEMP_MIN, LM77_TEMP_MAX);
179 mutex_lock(&data->update_lock);
180 data->temp[nr] = val;
181 lm77_write_value(client, temp_regs[nr], LM77_TEMP_TO_REG(val));
182 mutex_unlock(&data->update_lock);
183 return count;
184}
185
186/*
187 * hysteresis is stored as a relative value on the chip, so it has to be
188 * converted first.
189 */
190static ssize_t temp_hyst_store(struct device *dev,
191 struct device_attribute *devattr,
192 const char *buf, size_t count)
193{
194 struct lm77_data *data = dev_get_drvdata(dev);
195 struct i2c_client *client = data->client;
196 long val;
197 int err;
198
199 err = kstrtol(buf, 10, &val);
200 if (err)
201 return err;
202
203 mutex_lock(&data->update_lock);
204 val = clamp_val(data->temp[t_crit] - val, LM77_TEMP_MIN, LM77_TEMP_MAX);
205 data->temp[t_hyst] = val;
206 lm77_write_value(client, LM77_REG_TEMP_HYST,
207 LM77_TEMP_TO_REG(data->temp[t_hyst]));
208 mutex_unlock(&data->update_lock);
209 return count;
210}
211
212static ssize_t alarm_show(struct device *dev, struct device_attribute *attr,
213 char *buf)
214{
215 int bitnr = to_sensor_dev_attr(attr)->index;
216 struct lm77_data *data = lm77_update_device(dev);
217 return sprintf(buf, "%u\n", (data->alarms >> bitnr) & 1);
218}
219
220static SENSOR_DEVICE_ATTR_RO(temp1_input, temp, t_input);
221static SENSOR_DEVICE_ATTR_RW(temp1_crit, temp, t_crit);
222static SENSOR_DEVICE_ATTR_RW(temp1_min, temp, t_min);
223static SENSOR_DEVICE_ATTR_RW(temp1_max, temp, t_max);
224
225static SENSOR_DEVICE_ATTR_RW(temp1_crit_hyst, temp_hyst, t_crit);
226static SENSOR_DEVICE_ATTR_RO(temp1_min_hyst, temp_hyst, t_min);
227static SENSOR_DEVICE_ATTR_RO(temp1_max_hyst, temp_hyst, t_max);
228
229static SENSOR_DEVICE_ATTR_RO(temp1_crit_alarm, alarm, 2);
230static SENSOR_DEVICE_ATTR_RO(temp1_min_alarm, alarm, 0);
231static SENSOR_DEVICE_ATTR_RO(temp1_max_alarm, alarm, 1);
232
233static struct attribute *lm77_attrs[] = {
234 &sensor_dev_attr_temp1_input.dev_attr.attr,
235 &sensor_dev_attr_temp1_crit.dev_attr.attr,
236 &sensor_dev_attr_temp1_min.dev_attr.attr,
237 &sensor_dev_attr_temp1_max.dev_attr.attr,
238 &sensor_dev_attr_temp1_crit_hyst.dev_attr.attr,
239 &sensor_dev_attr_temp1_min_hyst.dev_attr.attr,
240 &sensor_dev_attr_temp1_max_hyst.dev_attr.attr,
241 &sensor_dev_attr_temp1_crit_alarm.dev_attr.attr,
242 &sensor_dev_attr_temp1_min_alarm.dev_attr.attr,
243 &sensor_dev_attr_temp1_max_alarm.dev_attr.attr,
244 NULL
245};
246ATTRIBUTE_GROUPS(lm77);
247
248/* Return 0 if detection is successful, -ENODEV otherwise */
249static int lm77_detect(struct i2c_client *client, struct i2c_board_info *info)
250{
251 struct i2c_adapter *adapter = client->adapter;
252 int i, cur, conf, hyst, crit, min, max;
253
254 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
255 I2C_FUNC_SMBUS_WORD_DATA))
256 return -ENODEV;
257
258 /*
259 * Here comes the remaining detection. Since the LM77 has no
260 * register dedicated to identification, we have to rely on the
261 * following tricks:
262 *
263 * 1. the high 4 bits represent the sign and thus they should
264 * always be the same
265 * 2. the high 3 bits are unused in the configuration register
266 * 3. addresses 0x06 and 0x07 return the last read value
267 * 4. registers cycling over 8-address boundaries
268 *
269 * Word-sized registers are high-byte first.
270 */
271
272 /* addresses cycling */
273 cur = i2c_smbus_read_word_data(client, 0);
274 conf = i2c_smbus_read_byte_data(client, 1);
275 hyst = i2c_smbus_read_word_data(client, 2);
276 crit = i2c_smbus_read_word_data(client, 3);
277 min = i2c_smbus_read_word_data(client, 4);
278 max = i2c_smbus_read_word_data(client, 5);
279 for (i = 8; i <= 0xff; i += 8) {
280 if (i2c_smbus_read_byte_data(client, i + 1) != conf
281 || i2c_smbus_read_word_data(client, i + 2) != hyst
282 || i2c_smbus_read_word_data(client, i + 3) != crit
283 || i2c_smbus_read_word_data(client, i + 4) != min
284 || i2c_smbus_read_word_data(client, i + 5) != max)
285 return -ENODEV;
286 }
287
288 /* sign bits */
289 if (((cur & 0x00f0) != 0xf0 && (cur & 0x00f0) != 0x0)
290 || ((hyst & 0x00f0) != 0xf0 && (hyst & 0x00f0) != 0x0)
291 || ((crit & 0x00f0) != 0xf0 && (crit & 0x00f0) != 0x0)
292 || ((min & 0x00f0) != 0xf0 && (min & 0x00f0) != 0x0)
293 || ((max & 0x00f0) != 0xf0 && (max & 0x00f0) != 0x0))
294 return -ENODEV;
295
296 /* unused bits */
297 if (conf & 0xe0)
298 return -ENODEV;
299
300 /* 0x06 and 0x07 return the last read value */
301 cur = i2c_smbus_read_word_data(client, 0);
302 if (i2c_smbus_read_word_data(client, 6) != cur
303 || i2c_smbus_read_word_data(client, 7) != cur)
304 return -ENODEV;
305 hyst = i2c_smbus_read_word_data(client, 2);
306 if (i2c_smbus_read_word_data(client, 6) != hyst
307 || i2c_smbus_read_word_data(client, 7) != hyst)
308 return -ENODEV;
309 min = i2c_smbus_read_word_data(client, 4);
310 if (i2c_smbus_read_word_data(client, 6) != min
311 || i2c_smbus_read_word_data(client, 7) != min)
312 return -ENODEV;
313
314 strlcpy(info->type, "lm77", I2C_NAME_SIZE);
315
316 return 0;
317}
318
319static void lm77_init_client(struct i2c_client *client)
320{
321 /* Initialize the LM77 chip - turn off shutdown mode */
322 int conf = lm77_read_value(client, LM77_REG_CONF);
323 if (conf & 1)
324 lm77_write_value(client, LM77_REG_CONF, conf & 0xfe);
325}
326
327static int lm77_probe(struct i2c_client *client, const struct i2c_device_id *id)
328{
329 struct device *dev = &client->dev;
330 struct device *hwmon_dev;
331 struct lm77_data *data;
332
333 data = devm_kzalloc(dev, sizeof(struct lm77_data), GFP_KERNEL);
334 if (!data)
335 return -ENOMEM;
336
337 data->client = client;
338 mutex_init(&data->update_lock);
339
340 /* Initialize the LM77 chip */
341 lm77_init_client(client);
342
343 hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
344 data, lm77_groups);
345 return PTR_ERR_OR_ZERO(hwmon_dev);
346}
347
348static const struct i2c_device_id lm77_id[] = {
349 { "lm77", 0 },
350 { }
351};
352MODULE_DEVICE_TABLE(i2c, lm77_id);
353
354/* This is the driver that will be inserted */
355static struct i2c_driver lm77_driver = {
356 .class = I2C_CLASS_HWMON,
357 .driver = {
358 .name = "lm77",
359 },
360 .probe = lm77_probe,
361 .id_table = lm77_id,
362 .detect = lm77_detect,
363 .address_list = normal_i2c,
364};
365
366module_i2c_driver(lm77_driver);
367
368MODULE_AUTHOR("Andras BALI <drewie@freemail.hu>");
369MODULE_DESCRIPTION("LM77 driver");
370MODULE_LICENSE("GPL");
371