1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Driver for MAX31730 3-Channel Remote Temperature Sensor
4 *
5 * Copyright (c) 2019 Guenter Roeck <linux@roeck-us.net>
6 */
7
8 #include <linux/bits.h>
9 #include <linux/err.h>
10 #include <linux/i2c.h>
11 #include <linux/init.h>
12 #include <linux/hwmon.h>
13 #include <linux/module.h>
14 #include <linux/of_device.h>
15 #include <linux/of.h>
16 #include <linux/slab.h>
17
18 /* Addresses scanned */
19 static const unsigned short normal_i2c[] = { 0x1c, 0x1d, 0x1e, 0x1f, 0x4c,
20 0x4d, 0x4e, 0x4f, I2C_CLIENT_END };
21
22 /* The MAX31730 registers */
23 #define MAX31730_REG_TEMP 0x00
24 #define MAX31730_REG_CONF 0x13
25 #define MAX31730_STOP BIT(7)
26 #define MAX31730_EXTRANGE BIT(1)
27 #define MAX31730_REG_TEMP_OFFSET 0x16
28 #define MAX31730_TEMP_OFFSET_BASELINE 0x77
29 #define MAX31730_REG_OFFSET_ENABLE 0x17
30 #define MAX31730_REG_TEMP_MAX 0x20
31 #define MAX31730_REG_TEMP_MIN 0x30
32 #define MAX31730_REG_STATUS_HIGH 0x32
33 #define MAX31730_REG_STATUS_LOW 0x33
34 #define MAX31730_REG_CHANNEL_ENABLE 0x35
35 #define MAX31730_REG_TEMP_FAULT 0x36
36
37 #define MAX31730_REG_MFG_ID 0x50
38 #define MAX31730_MFG_ID 0x4d
39 #define MAX31730_REG_MFG_REV 0x51
40 #define MAX31730_MFG_REV 0x01
41
42 #define MAX31730_TEMP_MIN (-128000)
43 #define MAX31730_TEMP_MAX 127937
44
45 /* Each client has this additional data */
46 struct max31730_data {
47 struct i2c_client *client;
48 u8 orig_conf;
49 u8 current_conf;
50 u8 offset_enable;
51 u8 channel_enable;
52 };
53
54 /*-----------------------------------------------------------------------*/
55
max31730_reg_to_mc(s16 temp)56 static inline long max31730_reg_to_mc(s16 temp)
57 {
58 return DIV_ROUND_CLOSEST((temp >> 4) * 1000, 16);
59 }
60
max31730_write_config(struct max31730_data * data,u8 set_mask,u8 clr_mask)61 static int max31730_write_config(struct max31730_data *data, u8 set_mask,
62 u8 clr_mask)
63 {
64 u8 value;
65
66 clr_mask |= MAX31730_EXTRANGE;
67 value = data->current_conf & ~clr_mask;
68 value |= set_mask;
69
70 if (data->current_conf != value) {
71 s32 err;
72
73 err = i2c_smbus_write_byte_data(data->client, MAX31730_REG_CONF,
74 value);
75 if (err)
76 return err;
77 data->current_conf = value;
78 }
79 return 0;
80 }
81
max31730_set_enable(struct i2c_client * client,int reg,u8 * confdata,int channel,bool enable)82 static int max31730_set_enable(struct i2c_client *client, int reg,
83 u8 *confdata, int channel, bool enable)
84 {
85 u8 regval = *confdata;
86 int err;
87
88 if (enable)
89 regval |= BIT(channel);
90 else
91 regval &= ~BIT(channel);
92
93 if (regval != *confdata) {
94 err = i2c_smbus_write_byte_data(client, reg, regval);
95 if (err)
96 return err;
97 *confdata = regval;
98 }
99 return 0;
100 }
101
max31730_set_offset_enable(struct max31730_data * data,int channel,bool enable)102 static int max31730_set_offset_enable(struct max31730_data *data, int channel,
103 bool enable)
104 {
105 return max31730_set_enable(data->client, MAX31730_REG_OFFSET_ENABLE,
106 &data->offset_enable, channel, enable);
107 }
108
max31730_set_channel_enable(struct max31730_data * data,int channel,bool enable)109 static int max31730_set_channel_enable(struct max31730_data *data, int channel,
110 bool enable)
111 {
112 return max31730_set_enable(data->client, MAX31730_REG_CHANNEL_ENABLE,
113 &data->channel_enable, channel, enable);
114 }
115
max31730_read(struct device * dev,enum hwmon_sensor_types type,u32 attr,int channel,long * val)116 static int max31730_read(struct device *dev, enum hwmon_sensor_types type,
117 u32 attr, int channel, long *val)
118 {
119 struct max31730_data *data = dev_get_drvdata(dev);
120 int regval, reg, offset;
121
122 if (type != hwmon_temp)
123 return -EINVAL;
124
125 switch (attr) {
126 case hwmon_temp_input:
127 if (!(data->channel_enable & BIT(channel)))
128 return -ENODATA;
129 reg = MAX31730_REG_TEMP + (channel * 2);
130 break;
131 case hwmon_temp_max:
132 reg = MAX31730_REG_TEMP_MAX + (channel * 2);
133 break;
134 case hwmon_temp_min:
135 reg = MAX31730_REG_TEMP_MIN;
136 break;
137 case hwmon_temp_enable:
138 *val = !!(data->channel_enable & BIT(channel));
139 return 0;
140 case hwmon_temp_offset:
141 if (!channel)
142 return -EINVAL;
143 if (!(data->offset_enable & BIT(channel))) {
144 *val = 0;
145 return 0;
146 }
147 offset = i2c_smbus_read_byte_data(data->client,
148 MAX31730_REG_TEMP_OFFSET);
149 if (offset < 0)
150 return offset;
151 *val = (offset - MAX31730_TEMP_OFFSET_BASELINE) * 125;
152 return 0;
153 case hwmon_temp_fault:
154 regval = i2c_smbus_read_byte_data(data->client,
155 MAX31730_REG_TEMP_FAULT);
156 if (regval < 0)
157 return regval;
158 *val = !!(regval & BIT(channel));
159 return 0;
160 case hwmon_temp_min_alarm:
161 regval = i2c_smbus_read_byte_data(data->client,
162 MAX31730_REG_STATUS_LOW);
163 if (regval < 0)
164 return regval;
165 *val = !!(regval & BIT(channel));
166 return 0;
167 case hwmon_temp_max_alarm:
168 regval = i2c_smbus_read_byte_data(data->client,
169 MAX31730_REG_STATUS_HIGH);
170 if (regval < 0)
171 return regval;
172 *val = !!(regval & BIT(channel));
173 return 0;
174 default:
175 return -EINVAL;
176 }
177 regval = i2c_smbus_read_word_swapped(data->client, reg);
178 if (regval < 0)
179 return regval;
180
181 *val = max31730_reg_to_mc(regval);
182
183 return 0;
184 }
185
max31730_write(struct device * dev,enum hwmon_sensor_types type,u32 attr,int channel,long val)186 static int max31730_write(struct device *dev, enum hwmon_sensor_types type,
187 u32 attr, int channel, long val)
188 {
189 struct max31730_data *data = dev_get_drvdata(dev);
190 int reg, err;
191
192 if (type != hwmon_temp)
193 return -EINVAL;
194
195 switch (attr) {
196 case hwmon_temp_max:
197 reg = MAX31730_REG_TEMP_MAX + channel * 2;
198 break;
199 case hwmon_temp_min:
200 reg = MAX31730_REG_TEMP_MIN;
201 break;
202 case hwmon_temp_enable:
203 if (val != 0 && val != 1)
204 return -EINVAL;
205 return max31730_set_channel_enable(data, channel, val);
206 case hwmon_temp_offset:
207 val = clamp_val(val, -14875, 17000) + 14875;
208 val = DIV_ROUND_CLOSEST(val, 125);
209 err = max31730_set_offset_enable(data, channel,
210 val != MAX31730_TEMP_OFFSET_BASELINE);
211 if (err)
212 return err;
213 return i2c_smbus_write_byte_data(data->client,
214 MAX31730_REG_TEMP_OFFSET, val);
215 default:
216 return -EINVAL;
217 }
218
219 val = clamp_val(val, MAX31730_TEMP_MIN, MAX31730_TEMP_MAX);
220 val = DIV_ROUND_CLOSEST(val << 4, 1000) << 4;
221
222 return i2c_smbus_write_word_swapped(data->client, reg, (u16)val);
223 }
224
max31730_is_visible(const void * data,enum hwmon_sensor_types type,u32 attr,int channel)225 static umode_t max31730_is_visible(const void *data,
226 enum hwmon_sensor_types type,
227 u32 attr, int channel)
228 {
229 switch (type) {
230 case hwmon_temp:
231 switch (attr) {
232 case hwmon_temp_input:
233 case hwmon_temp_min_alarm:
234 case hwmon_temp_max_alarm:
235 case hwmon_temp_fault:
236 return 0444;
237 case hwmon_temp_min:
238 return channel ? 0444 : 0644;
239 case hwmon_temp_offset:
240 case hwmon_temp_enable:
241 case hwmon_temp_max:
242 return 0644;
243 }
244 break;
245 default:
246 break;
247 }
248 return 0;
249 }
250
251 static const struct hwmon_channel_info *max31730_info[] = {
252 HWMON_CHANNEL_INFO(chip,
253 HWMON_C_REGISTER_TZ),
254 HWMON_CHANNEL_INFO(temp,
255 HWMON_T_INPUT | HWMON_T_MIN | HWMON_T_MAX |
256 HWMON_T_ENABLE |
257 HWMON_T_MIN_ALARM | HWMON_T_MAX_ALARM,
258 HWMON_T_INPUT | HWMON_T_MIN | HWMON_T_MAX |
259 HWMON_T_OFFSET | HWMON_T_ENABLE |
260 HWMON_T_MIN_ALARM | HWMON_T_MAX_ALARM |
261 HWMON_T_FAULT,
262 HWMON_T_INPUT | HWMON_T_MIN | HWMON_T_MAX |
263 HWMON_T_OFFSET | HWMON_T_ENABLE |
264 HWMON_T_MIN_ALARM | HWMON_T_MAX_ALARM |
265 HWMON_T_FAULT,
266 HWMON_T_INPUT | HWMON_T_MIN | HWMON_T_MAX |
267 HWMON_T_OFFSET | HWMON_T_ENABLE |
268 HWMON_T_MIN_ALARM | HWMON_T_MAX_ALARM |
269 HWMON_T_FAULT
270 ),
271 NULL
272 };
273
274 static const struct hwmon_ops max31730_hwmon_ops = {
275 .is_visible = max31730_is_visible,
276 .read = max31730_read,
277 .write = max31730_write,
278 };
279
280 static const struct hwmon_chip_info max31730_chip_info = {
281 .ops = &max31730_hwmon_ops,
282 .info = max31730_info,
283 };
284
max31730_remove(void * data)285 static void max31730_remove(void *data)
286 {
287 struct max31730_data *max31730 = data;
288 struct i2c_client *client = max31730->client;
289
290 i2c_smbus_write_byte_data(client, MAX31730_REG_CONF,
291 max31730->orig_conf);
292 }
293
294 static int
max31730_probe(struct i2c_client * client)295 max31730_probe(struct i2c_client *client)
296 {
297 struct device *dev = &client->dev;
298 struct device *hwmon_dev;
299 struct max31730_data *data;
300 int status, err;
301
302 if (!i2c_check_functionality(client->adapter,
303 I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA))
304 return -EIO;
305
306 data = devm_kzalloc(dev, sizeof(struct max31730_data), GFP_KERNEL);
307 if (!data)
308 return -ENOMEM;
309
310 data->client = client;
311
312 /* Cache original configuration and enable status */
313 status = i2c_smbus_read_byte_data(client, MAX31730_REG_CHANNEL_ENABLE);
314 if (status < 0)
315 return status;
316 data->channel_enable = status;
317
318 status = i2c_smbus_read_byte_data(client, MAX31730_REG_OFFSET_ENABLE);
319 if (status < 0)
320 return status;
321 data->offset_enable = status;
322
323 status = i2c_smbus_read_byte_data(client, MAX31730_REG_CONF);
324 if (status < 0)
325 return status;
326 data->orig_conf = status;
327 data->current_conf = status;
328
329 err = max31730_write_config(data,
330 data->channel_enable ? 0 : MAX31730_STOP,
331 data->channel_enable ? MAX31730_STOP : 0);
332 if (err)
333 return err;
334
335 dev_set_drvdata(dev, data);
336
337 err = devm_add_action_or_reset(dev, max31730_remove, data);
338 if (err)
339 return err;
340
341 hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name,
342 data,
343 &max31730_chip_info,
344 NULL);
345 return PTR_ERR_OR_ZERO(hwmon_dev);
346 }
347
348 static const struct i2c_device_id max31730_ids[] = {
349 { "max31730", 0, },
350 { }
351 };
352 MODULE_DEVICE_TABLE(i2c, max31730_ids);
353
354 static const struct of_device_id __maybe_unused max31730_of_match[] = {
355 {
356 .compatible = "maxim,max31730",
357 },
358 { },
359 };
360 MODULE_DEVICE_TABLE(of, max31730_of_match);
361
max31730_check_reg_temp(struct i2c_client * client,int reg)362 static bool max31730_check_reg_temp(struct i2c_client *client,
363 int reg)
364 {
365 int regval;
366
367 regval = i2c_smbus_read_byte_data(client, reg + 1);
368 return regval < 0 || (regval & 0x0f);
369 }
370
371 /* Return 0 if detection is successful, -ENODEV otherwise */
max31730_detect(struct i2c_client * client,struct i2c_board_info * info)372 static int max31730_detect(struct i2c_client *client,
373 struct i2c_board_info *info)
374 {
375 struct i2c_adapter *adapter = client->adapter;
376 int regval;
377 int i;
378
379 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
380 I2C_FUNC_SMBUS_WORD_DATA))
381 return -ENODEV;
382
383 regval = i2c_smbus_read_byte_data(client, MAX31730_REG_MFG_ID);
384 if (regval != MAX31730_MFG_ID)
385 return -ENODEV;
386 regval = i2c_smbus_read_byte_data(client, MAX31730_REG_MFG_REV);
387 if (regval != MAX31730_MFG_REV)
388 return -ENODEV;
389
390 /* lower 4 bit of temperature and limit registers must be 0 */
391 if (max31730_check_reg_temp(client, MAX31730_REG_TEMP_MIN))
392 return -ENODEV;
393
394 for (i = 0; i < 4; i++) {
395 if (max31730_check_reg_temp(client, MAX31730_REG_TEMP + i * 2))
396 return -ENODEV;
397 if (max31730_check_reg_temp(client,
398 MAX31730_REG_TEMP_MAX + i * 2))
399 return -ENODEV;
400 }
401
402 strlcpy(info->type, "max31730", I2C_NAME_SIZE);
403
404 return 0;
405 }
406
max31730_suspend(struct device * dev)407 static int __maybe_unused max31730_suspend(struct device *dev)
408 {
409 struct max31730_data *data = dev_get_drvdata(dev);
410
411 return max31730_write_config(data, MAX31730_STOP, 0);
412 }
413
max31730_resume(struct device * dev)414 static int __maybe_unused max31730_resume(struct device *dev)
415 {
416 struct max31730_data *data = dev_get_drvdata(dev);
417
418 return max31730_write_config(data, 0, MAX31730_STOP);
419 }
420
421 static SIMPLE_DEV_PM_OPS(max31730_pm_ops, max31730_suspend, max31730_resume);
422
423 static struct i2c_driver max31730_driver = {
424 .class = I2C_CLASS_HWMON,
425 .driver = {
426 .name = "max31730",
427 .of_match_table = of_match_ptr(max31730_of_match),
428 .pm = &max31730_pm_ops,
429 },
430 .probe_new = max31730_probe,
431 .id_table = max31730_ids,
432 .detect = max31730_detect,
433 .address_list = normal_i2c,
434 };
435
436 module_i2c_driver(max31730_driver);
437
438 MODULE_AUTHOR("Guenter Roeck <linux@roeck-us.net>");
439 MODULE_DESCRIPTION("MAX31730 driver");
440 MODULE_LICENSE("GPL");
441