1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * lm77.c - Part of lm_sensors, Linux kernel modules for hardware
4 * monitoring
5 *
6 * Copyright (c) 2004 Andras BALI <drewie@freemail.hu>
7 *
8 * Heavily based on lm75.c by Frodo Looijaard <frodol@dds.nl>. The LM77
9 * is a temperature sensor and thermal window comparator with 0.5 deg
10 * resolution made by National Semiconductor. Complete datasheet can be
11 * obtained at their site:
12 * http://www.national.com/pf/LM/LM77.html
13 */
14
15 #include <linux/module.h>
16 #include <linux/init.h>
17 #include <linux/slab.h>
18 #include <linux/jiffies.h>
19 #include <linux/i2c.h>
20 #include <linux/hwmon.h>
21 #include <linux/hwmon-sysfs.h>
22 #include <linux/err.h>
23 #include <linux/mutex.h>
24
25 /* Addresses to scan */
26 static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b,
27 I2C_CLIENT_END };
28
29 /* The LM77 registers */
30 #define LM77_REG_TEMP 0x00
31 #define LM77_REG_CONF 0x01
32 #define LM77_REG_TEMP_HYST 0x02
33 #define LM77_REG_TEMP_CRIT 0x03
34 #define LM77_REG_TEMP_MIN 0x04
35 #define LM77_REG_TEMP_MAX 0x05
36
37 enum temp_index {
38 t_input = 0,
39 t_crit,
40 t_min,
41 t_max,
42 t_hyst,
43 t_num_temp
44 };
45
46 static const u8 temp_regs[t_num_temp] = {
47 [t_input] = LM77_REG_TEMP,
48 [t_min] = LM77_REG_TEMP_MIN,
49 [t_max] = LM77_REG_TEMP_MAX,
50 [t_crit] = LM77_REG_TEMP_CRIT,
51 [t_hyst] = LM77_REG_TEMP_HYST,
52 };
53
54 /* Each client has this additional data */
55 struct lm77_data {
56 struct i2c_client *client;
57 struct mutex update_lock;
58 char valid;
59 unsigned long last_updated; /* In jiffies */
60 int temp[t_num_temp]; /* index using temp_index */
61 u8 alarms;
62 };
63
64 /* straight from the datasheet */
65 #define LM77_TEMP_MIN (-55000)
66 #define LM77_TEMP_MAX 125000
67
68 /*
69 * In the temperature registers, the low 3 bits are not part of the
70 * temperature values; they are the status bits.
71 */
LM77_TEMP_TO_REG(int temp)72 static inline s16 LM77_TEMP_TO_REG(int temp)
73 {
74 return (temp / 500) * 8;
75 }
76
LM77_TEMP_FROM_REG(s16 reg)77 static inline int LM77_TEMP_FROM_REG(s16 reg)
78 {
79 return (reg / 8) * 500;
80 }
81
82 /*
83 * All registers are word-sized, except for the configuration register.
84 * The LM77 uses the high-byte first convention.
85 */
lm77_read_value(struct i2c_client * client,u8 reg)86 static u16 lm77_read_value(struct i2c_client *client, u8 reg)
87 {
88 if (reg == LM77_REG_CONF)
89 return i2c_smbus_read_byte_data(client, reg);
90 else
91 return i2c_smbus_read_word_swapped(client, reg);
92 }
93
lm77_write_value(struct i2c_client * client,u8 reg,u16 value)94 static int lm77_write_value(struct i2c_client *client, u8 reg, u16 value)
95 {
96 if (reg == LM77_REG_CONF)
97 return i2c_smbus_write_byte_data(client, reg, value);
98 else
99 return i2c_smbus_write_word_swapped(client, reg, value);
100 }
101
lm77_update_device(struct device * dev)102 static struct lm77_data *lm77_update_device(struct device *dev)
103 {
104 struct lm77_data *data = dev_get_drvdata(dev);
105 struct i2c_client *client = data->client;
106 int i;
107
108 mutex_lock(&data->update_lock);
109
110 if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
111 || !data->valid) {
112 dev_dbg(&client->dev, "Starting lm77 update\n");
113 for (i = 0; i < t_num_temp; i++) {
114 data->temp[i] =
115 LM77_TEMP_FROM_REG(lm77_read_value(client,
116 temp_regs[i]));
117 }
118 data->alarms =
119 lm77_read_value(client, LM77_REG_TEMP) & 0x0007;
120 data->last_updated = jiffies;
121 data->valid = 1;
122 }
123
124 mutex_unlock(&data->update_lock);
125
126 return data;
127 }
128
129 /* sysfs stuff */
130
temp_show(struct device * dev,struct device_attribute * devattr,char * buf)131 static ssize_t temp_show(struct device *dev, struct device_attribute *devattr,
132 char *buf)
133 {
134 struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
135 struct lm77_data *data = lm77_update_device(dev);
136
137 return sprintf(buf, "%d\n", data->temp[attr->index]);
138 }
139
temp_hyst_show(struct device * dev,struct device_attribute * devattr,char * buf)140 static ssize_t temp_hyst_show(struct device *dev,
141 struct device_attribute *devattr, char *buf)
142 {
143 struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
144 struct lm77_data *data = lm77_update_device(dev);
145 int nr = attr->index;
146 int temp;
147
148 temp = nr == t_min ? data->temp[nr] + data->temp[t_hyst] :
149 data->temp[nr] - data->temp[t_hyst];
150
151 return sprintf(buf, "%d\n", temp);
152 }
153
temp_store(struct device * dev,struct device_attribute * devattr,const char * buf,size_t count)154 static ssize_t temp_store(struct device *dev,
155 struct device_attribute *devattr, const char *buf,
156 size_t count)
157 {
158 struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
159 struct lm77_data *data = dev_get_drvdata(dev);
160 struct i2c_client *client = data->client;
161 int nr = attr->index;
162 long val;
163 int err;
164
165 err = kstrtol(buf, 10, &val);
166 if (err)
167 return err;
168
169 val = clamp_val(val, LM77_TEMP_MIN, LM77_TEMP_MAX);
170 mutex_lock(&data->update_lock);
171 data->temp[nr] = val;
172 lm77_write_value(client, temp_regs[nr], LM77_TEMP_TO_REG(val));
173 mutex_unlock(&data->update_lock);
174 return count;
175 }
176
177 /*
178 * hysteresis is stored as a relative value on the chip, so it has to be
179 * converted first.
180 */
temp_hyst_store(struct device * dev,struct device_attribute * devattr,const char * buf,size_t count)181 static ssize_t temp_hyst_store(struct device *dev,
182 struct device_attribute *devattr,
183 const char *buf, size_t count)
184 {
185 struct lm77_data *data = dev_get_drvdata(dev);
186 struct i2c_client *client = data->client;
187 long val;
188 int err;
189
190 err = kstrtol(buf, 10, &val);
191 if (err)
192 return err;
193
194 mutex_lock(&data->update_lock);
195 val = clamp_val(data->temp[t_crit] - val, LM77_TEMP_MIN, LM77_TEMP_MAX);
196 data->temp[t_hyst] = val;
197 lm77_write_value(client, LM77_REG_TEMP_HYST,
198 LM77_TEMP_TO_REG(data->temp[t_hyst]));
199 mutex_unlock(&data->update_lock);
200 return count;
201 }
202
alarm_show(struct device * dev,struct device_attribute * attr,char * buf)203 static ssize_t alarm_show(struct device *dev, struct device_attribute *attr,
204 char *buf)
205 {
206 int bitnr = to_sensor_dev_attr(attr)->index;
207 struct lm77_data *data = lm77_update_device(dev);
208 return sprintf(buf, "%u\n", (data->alarms >> bitnr) & 1);
209 }
210
211 static SENSOR_DEVICE_ATTR_RO(temp1_input, temp, t_input);
212 static SENSOR_DEVICE_ATTR_RW(temp1_crit, temp, t_crit);
213 static SENSOR_DEVICE_ATTR_RW(temp1_min, temp, t_min);
214 static SENSOR_DEVICE_ATTR_RW(temp1_max, temp, t_max);
215
216 static SENSOR_DEVICE_ATTR_RW(temp1_crit_hyst, temp_hyst, t_crit);
217 static SENSOR_DEVICE_ATTR_RO(temp1_min_hyst, temp_hyst, t_min);
218 static SENSOR_DEVICE_ATTR_RO(temp1_max_hyst, temp_hyst, t_max);
219
220 static SENSOR_DEVICE_ATTR_RO(temp1_crit_alarm, alarm, 2);
221 static SENSOR_DEVICE_ATTR_RO(temp1_min_alarm, alarm, 0);
222 static SENSOR_DEVICE_ATTR_RO(temp1_max_alarm, alarm, 1);
223
224 static struct attribute *lm77_attrs[] = {
225 &sensor_dev_attr_temp1_input.dev_attr.attr,
226 &sensor_dev_attr_temp1_crit.dev_attr.attr,
227 &sensor_dev_attr_temp1_min.dev_attr.attr,
228 &sensor_dev_attr_temp1_max.dev_attr.attr,
229 &sensor_dev_attr_temp1_crit_hyst.dev_attr.attr,
230 &sensor_dev_attr_temp1_min_hyst.dev_attr.attr,
231 &sensor_dev_attr_temp1_max_hyst.dev_attr.attr,
232 &sensor_dev_attr_temp1_crit_alarm.dev_attr.attr,
233 &sensor_dev_attr_temp1_min_alarm.dev_attr.attr,
234 &sensor_dev_attr_temp1_max_alarm.dev_attr.attr,
235 NULL
236 };
237 ATTRIBUTE_GROUPS(lm77);
238
239 /* Return 0 if detection is successful, -ENODEV otherwise */
lm77_detect(struct i2c_client * client,struct i2c_board_info * info)240 static int lm77_detect(struct i2c_client *client, struct i2c_board_info *info)
241 {
242 struct i2c_adapter *adapter = client->adapter;
243 int i, cur, conf, hyst, crit, min, max;
244
245 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
246 I2C_FUNC_SMBUS_WORD_DATA))
247 return -ENODEV;
248
249 /*
250 * Here comes the remaining detection. Since the LM77 has no
251 * register dedicated to identification, we have to rely on the
252 * following tricks:
253 *
254 * 1. the high 4 bits represent the sign and thus they should
255 * always be the same
256 * 2. the high 3 bits are unused in the configuration register
257 * 3. addresses 0x06 and 0x07 return the last read value
258 * 4. registers cycling over 8-address boundaries
259 *
260 * Word-sized registers are high-byte first.
261 */
262
263 /* addresses cycling */
264 cur = i2c_smbus_read_word_data(client, 0);
265 conf = i2c_smbus_read_byte_data(client, 1);
266 hyst = i2c_smbus_read_word_data(client, 2);
267 crit = i2c_smbus_read_word_data(client, 3);
268 min = i2c_smbus_read_word_data(client, 4);
269 max = i2c_smbus_read_word_data(client, 5);
270 for (i = 8; i <= 0xff; i += 8) {
271 if (i2c_smbus_read_byte_data(client, i + 1) != conf
272 || i2c_smbus_read_word_data(client, i + 2) != hyst
273 || i2c_smbus_read_word_data(client, i + 3) != crit
274 || i2c_smbus_read_word_data(client, i + 4) != min
275 || i2c_smbus_read_word_data(client, i + 5) != max)
276 return -ENODEV;
277 }
278
279 /* sign bits */
280 if (((cur & 0x00f0) != 0xf0 && (cur & 0x00f0) != 0x0)
281 || ((hyst & 0x00f0) != 0xf0 && (hyst & 0x00f0) != 0x0)
282 || ((crit & 0x00f0) != 0xf0 && (crit & 0x00f0) != 0x0)
283 || ((min & 0x00f0) != 0xf0 && (min & 0x00f0) != 0x0)
284 || ((max & 0x00f0) != 0xf0 && (max & 0x00f0) != 0x0))
285 return -ENODEV;
286
287 /* unused bits */
288 if (conf & 0xe0)
289 return -ENODEV;
290
291 /* 0x06 and 0x07 return the last read value */
292 cur = i2c_smbus_read_word_data(client, 0);
293 if (i2c_smbus_read_word_data(client, 6) != cur
294 || i2c_smbus_read_word_data(client, 7) != cur)
295 return -ENODEV;
296 hyst = i2c_smbus_read_word_data(client, 2);
297 if (i2c_smbus_read_word_data(client, 6) != hyst
298 || i2c_smbus_read_word_data(client, 7) != hyst)
299 return -ENODEV;
300 min = i2c_smbus_read_word_data(client, 4);
301 if (i2c_smbus_read_word_data(client, 6) != min
302 || i2c_smbus_read_word_data(client, 7) != min)
303 return -ENODEV;
304
305 strlcpy(info->type, "lm77", I2C_NAME_SIZE);
306
307 return 0;
308 }
309
lm77_init_client(struct i2c_client * client)310 static void lm77_init_client(struct i2c_client *client)
311 {
312 /* Initialize the LM77 chip - turn off shutdown mode */
313 int conf = lm77_read_value(client, LM77_REG_CONF);
314 if (conf & 1)
315 lm77_write_value(client, LM77_REG_CONF, conf & 0xfe);
316 }
317
lm77_probe(struct i2c_client * client)318 static int lm77_probe(struct i2c_client *client)
319 {
320 struct device *dev = &client->dev;
321 struct device *hwmon_dev;
322 struct lm77_data *data;
323
324 data = devm_kzalloc(dev, sizeof(struct lm77_data), GFP_KERNEL);
325 if (!data)
326 return -ENOMEM;
327
328 data->client = client;
329 mutex_init(&data->update_lock);
330
331 /* Initialize the LM77 chip */
332 lm77_init_client(client);
333
334 hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
335 data, lm77_groups);
336 return PTR_ERR_OR_ZERO(hwmon_dev);
337 }
338
339 static const struct i2c_device_id lm77_id[] = {
340 { "lm77", 0 },
341 { }
342 };
343 MODULE_DEVICE_TABLE(i2c, lm77_id);
344
345 /* This is the driver that will be inserted */
346 static struct i2c_driver lm77_driver = {
347 .class = I2C_CLASS_HWMON,
348 .driver = {
349 .name = "lm77",
350 },
351 .probe_new = lm77_probe,
352 .id_table = lm77_id,
353 .detect = lm77_detect,
354 .address_list = normal_i2c,
355 };
356
357 module_i2c_driver(lm77_driver);
358
359 MODULE_AUTHOR("Andras BALI <drewie@freemail.hu>");
360 MODULE_DESCRIPTION("LM77 driver");
361 MODULE_LICENSE("GPL");
362
