1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * Hardware monitoring driver for EMC2305 fan controller
4 *
5 * Copyright (C) 2022 Nvidia Technologies Ltd.
6 */
7
8 #include <linux/err.h>
9 #include <linux/hwmon.h>
10 #include <linux/i2c.h>
11 #include <linux/module.h>
12 #include <linux/platform_data/emc2305.h>
13 #include <linux/thermal.h>
14
15 #define EMC2305_REG_DRIVE_FAIL_STATUS 0x27
16 #define EMC2305_REG_VENDOR 0xfe
17 #define EMC2305_FAN_MAX 0xff
18 #define EMC2305_FAN_MIN 0x00
19 #define EMC2305_FAN_MAX_STATE 10
20 #define EMC2305_DEVICE 0x34
21 #define EMC2305_VENDOR 0x5d
22 #define EMC2305_REG_PRODUCT_ID 0xfd
23 #define EMC2305_TACH_REGS_UNUSE_BITS 3
24 #define EMC2305_TACH_CNT_MULTIPLIER 0x02
25 #define EMC2305_TACH_RANGE_MIN 480
26
27 #define EMC2305_PWM_DUTY2STATE(duty, max_state, pwm_max) \
28 DIV_ROUND_CLOSEST((duty) * (max_state), (pwm_max))
29 #define EMC2305_PWM_STATE2DUTY(state, max_state, pwm_max) \
30 DIV_ROUND_CLOSEST((state) * (pwm_max), (max_state))
31
32 /*
33 * Factor by equations [2] and [3] from data sheet; valid for fans where the number of edges
34 * equal (poles * 2 + 1).
35 */
36 #define EMC2305_RPM_FACTOR 3932160
37
38 #define EMC2305_REG_FAN_DRIVE(n) (0x30 + 0x10 * (n))
39 #define EMC2305_REG_FAN_MIN_DRIVE(n) (0x38 + 0x10 * (n))
40 #define EMC2305_REG_FAN_TACH(n) (0x3e + 0x10 * (n))
41
42 enum emc230x_product_id {
43 EMC2305 = 0x34,
44 EMC2303 = 0x35,
45 EMC2302 = 0x36,
46 EMC2301 = 0x37,
47 };
48
49 static const struct i2c_device_id emc2305_ids[] = {
50 { "emc2305" },
51 { "emc2303" },
52 { "emc2302" },
53 { "emc2301" },
54 { }
55 };
56 MODULE_DEVICE_TABLE(i2c, emc2305_ids);
57
58 /**
59 * struct emc2305_cdev_data - device-specific cooling device state
60 * @cdev: cooling device
61 * @cur_state: cooling current state
62 * @last_hwmon_state: last cooling state updated by hwmon subsystem
63 * @last_thermal_state: last cooling state updated by thermal subsystem
64 *
65 * The 'last_hwmon_state' and 'last_thermal_state' fields are provided to support fan low limit
66 * speed feature. The purpose of this feature is to provides ability to limit fan speed
67 * according to some system wise considerations, like absence of some replaceable units (PSU or
68 * line cards), high system ambient temperature, unreliable transceivers temperature sensing or
69 * some other factors which indirectly impacts system's airflow
70 * Fan low limit feature is supported through 'hwmon' interface: 'hwmon' 'pwm' attribute is
71 * used for setting low limit for fan speed in case 'thermal' subsystem is configured in
72 * kernel. In this case setting fan speed through 'hwmon' will never let the 'thermal'
73 * subsystem to select a lower duty cycle than the duty cycle selected with the 'pwm'
74 * attribute.
75 * From other side, fan speed is to be updated in hardware through 'pwm' only in case the
76 * requested fan speed is above last speed set by 'thermal' subsystem, otherwise requested fan
77 * speed will be just stored with no PWM update.
78 */
79 struct emc2305_cdev_data {
80 struct thermal_cooling_device *cdev;
81 unsigned int cur_state;
82 unsigned long last_hwmon_state;
83 unsigned long last_thermal_state;
84 };
85
86 /**
87 * struct emc2305_data - device-specific data
88 * @client: i2c client
89 * @hwmon_dev: hwmon device
90 * @max_state: maximum cooling state of the cooling device
91 * @pwm_num: number of PWM channels
92 * @pwm_separate: separate PWM settings for every channel
93 * @pwm_min: array of minimum PWM per channel
94 * @cdev_data: array of cooling devices data
95 */
96 struct emc2305_data {
97 struct i2c_client *client;
98 struct device *hwmon_dev;
99 u8 max_state;
100 u8 pwm_num;
101 bool pwm_separate;
102 u8 pwm_min[EMC2305_PWM_MAX];
103 struct emc2305_cdev_data cdev_data[EMC2305_PWM_MAX];
104 };
105
106 static char *emc2305_fan_name[] = {
107 "emc2305_fan",
108 "emc2305_fan1",
109 "emc2305_fan2",
110 "emc2305_fan3",
111 "emc2305_fan4",
112 "emc2305_fan5",
113 };
114
115 static void emc2305_unset_tz(struct device *dev);
116
emc2305_get_max_channel(const struct emc2305_data * data)117 static int emc2305_get_max_channel(const struct emc2305_data *data)
118 {
119 return data->pwm_num;
120 }
121
emc2305_get_cdev_idx(struct thermal_cooling_device * cdev)122 static int emc2305_get_cdev_idx(struct thermal_cooling_device *cdev)
123 {
124 struct emc2305_data *data = cdev->devdata;
125 size_t len = strlen(cdev->type);
126 int ret;
127
128 if (len <= 0)
129 return -EINVAL;
130
131 /*
132 * Returns index of cooling device 0..4 in case of separate PWM setting.
133 * Zero index is used in case of one common PWM setting.
134 * If the mode is not set as pwm_separate, all PWMs are to be bound
135 * to the common thermal zone and should work at the same speed
136 * to perform cooling for the same thermal junction.
137 * Otherwise, return specific channel that will be used in bound
138 * related PWM to the thermal zone.
139 */
140 if (!data->pwm_separate)
141 return 0;
142
143 ret = cdev->type[len - 1];
144 switch (ret) {
145 case '1' ... '5':
146 return ret - '1';
147 default:
148 break;
149 }
150 return -EINVAL;
151 }
152
emc2305_get_cur_state(struct thermal_cooling_device * cdev,unsigned long * state)153 static int emc2305_get_cur_state(struct thermal_cooling_device *cdev, unsigned long *state)
154 {
155 int cdev_idx;
156 struct emc2305_data *data = cdev->devdata;
157
158 cdev_idx = emc2305_get_cdev_idx(cdev);
159 if (cdev_idx < 0)
160 return cdev_idx;
161
162 *state = data->cdev_data[cdev_idx].cur_state;
163 return 0;
164 }
165
emc2305_get_max_state(struct thermal_cooling_device * cdev,unsigned long * state)166 static int emc2305_get_max_state(struct thermal_cooling_device *cdev, unsigned long *state)
167 {
168 struct emc2305_data *data = cdev->devdata;
169 *state = data->max_state;
170 return 0;
171 }
172
__emc2305_set_cur_state(struct emc2305_data * data,int cdev_idx,unsigned long state)173 static int __emc2305_set_cur_state(struct emc2305_data *data, int cdev_idx, unsigned long state)
174 {
175 int ret;
176 struct i2c_client *client = data->client;
177 u8 val, i;
178
179 state = max_t(unsigned long, state, data->cdev_data[cdev_idx].last_hwmon_state);
180
181 val = EMC2305_PWM_STATE2DUTY(state, data->max_state, EMC2305_FAN_MAX);
182
183 data->cdev_data[cdev_idx].cur_state = state;
184 if (data->pwm_separate) {
185 ret = i2c_smbus_write_byte_data(client, EMC2305_REG_FAN_DRIVE(cdev_idx), val);
186 if (ret < 0)
187 return ret;
188 } else {
189 /*
190 * Set the same PWM value in all channels
191 * if common PWM channel is used.
192 */
193 for (i = 0; i < data->pwm_num; i++) {
194 ret = i2c_smbus_write_byte_data(client, EMC2305_REG_FAN_DRIVE(i), val);
195 if (ret < 0)
196 return ret;
197 }
198 }
199
200 return 0;
201 }
202
emc2305_set_cur_state(struct thermal_cooling_device * cdev,unsigned long state)203 static int emc2305_set_cur_state(struct thermal_cooling_device *cdev, unsigned long state)
204 {
205 int cdev_idx, ret;
206 struct emc2305_data *data = cdev->devdata;
207
208 if (state > data->max_state)
209 return -EINVAL;
210
211 cdev_idx = emc2305_get_cdev_idx(cdev);
212 if (cdev_idx < 0)
213 return cdev_idx;
214
215 /* Save thermal state. */
216 data->cdev_data[cdev_idx].last_thermal_state = state;
217 ret = __emc2305_set_cur_state(data, cdev_idx, state);
218 if (ret < 0)
219 return ret;
220
221 return 0;
222 }
223
224 static const struct thermal_cooling_device_ops emc2305_cooling_ops = {
225 .get_max_state = emc2305_get_max_state,
226 .get_cur_state = emc2305_get_cur_state,
227 .set_cur_state = emc2305_set_cur_state,
228 };
229
emc2305_show_fault(struct device * dev,int channel)230 static int emc2305_show_fault(struct device *dev, int channel)
231 {
232 struct emc2305_data *data = dev_get_drvdata(dev);
233 struct i2c_client *client = data->client;
234 int status_reg;
235
236 status_reg = i2c_smbus_read_byte_data(client, EMC2305_REG_DRIVE_FAIL_STATUS);
237 if (status_reg < 0)
238 return status_reg;
239
240 return status_reg & (1 << channel) ? 1 : 0;
241 }
242
emc2305_show_fan(struct device * dev,int channel)243 static int emc2305_show_fan(struct device *dev, int channel)
244 {
245 struct emc2305_data *data = dev_get_drvdata(dev);
246 struct i2c_client *client = data->client;
247 int ret;
248
249 ret = i2c_smbus_read_word_swapped(client, EMC2305_REG_FAN_TACH(channel));
250 if (ret <= 0)
251 return ret;
252
253 ret = ret >> EMC2305_TACH_REGS_UNUSE_BITS;
254 ret = EMC2305_RPM_FACTOR / ret;
255 if (ret <= EMC2305_TACH_RANGE_MIN)
256 return 0;
257
258 return ret * EMC2305_TACH_CNT_MULTIPLIER;
259 }
260
emc2305_show_pwm(struct device * dev,int channel)261 static int emc2305_show_pwm(struct device *dev, int channel)
262 {
263 struct emc2305_data *data = dev_get_drvdata(dev);
264 struct i2c_client *client = data->client;
265
266 return i2c_smbus_read_byte_data(client, EMC2305_REG_FAN_DRIVE(channel));
267 }
268
emc2305_set_pwm(struct device * dev,long val,int channel)269 static int emc2305_set_pwm(struct device *dev, long val, int channel)
270 {
271 struct emc2305_data *data = dev_get_drvdata(dev);
272 struct i2c_client *client = data->client;
273 int ret;
274
275 if (val < data->pwm_min[channel] || val > EMC2305_FAN_MAX)
276 return -EINVAL;
277
278 ret = i2c_smbus_write_byte_data(client, EMC2305_REG_FAN_DRIVE(channel), val);
279 if (ret < 0)
280 return ret;
281 data->cdev_data[channel].cur_state = EMC2305_PWM_DUTY2STATE(val, data->max_state,
282 EMC2305_FAN_MAX);
283 return 0;
284 }
285
emc2305_set_single_tz(struct device * dev,int idx)286 static int emc2305_set_single_tz(struct device *dev, int idx)
287 {
288 struct emc2305_data *data = dev_get_drvdata(dev);
289 long pwm;
290 int i, cdev_idx, ret;
291
292 cdev_idx = (idx) ? idx - 1 : 0;
293 pwm = data->pwm_min[cdev_idx];
294
295 data->cdev_data[cdev_idx].cdev =
296 thermal_cooling_device_register(emc2305_fan_name[idx], data,
297 &emc2305_cooling_ops);
298
299 if (IS_ERR(data->cdev_data[cdev_idx].cdev)) {
300 dev_err(dev, "Failed to register cooling device %s\n", emc2305_fan_name[idx]);
301 return PTR_ERR(data->cdev_data[cdev_idx].cdev);
302 }
303
304 if (data->cdev_data[cdev_idx].cur_state > 0)
305 /* Update pwm when temperature is above trips */
306 pwm = EMC2305_PWM_STATE2DUTY(data->cdev_data[cdev_idx].cur_state,
307 data->max_state, EMC2305_FAN_MAX);
308
309 /* Set minimal PWM speed. */
310 if (data->pwm_separate) {
311 ret = emc2305_set_pwm(dev, pwm, cdev_idx);
312 if (ret < 0)
313 return ret;
314 } else {
315 for (i = 0; i < data->pwm_num; i++) {
316 ret = emc2305_set_pwm(dev, pwm, i);
317 if (ret < 0)
318 return ret;
319 }
320 }
321 data->cdev_data[cdev_idx].cur_state =
322 EMC2305_PWM_DUTY2STATE(pwm, data->max_state,
323 EMC2305_FAN_MAX);
324 data->cdev_data[cdev_idx].last_hwmon_state =
325 EMC2305_PWM_DUTY2STATE(pwm, data->max_state,
326 EMC2305_FAN_MAX);
327 return 0;
328 }
329
emc2305_set_tz(struct device * dev)330 static int emc2305_set_tz(struct device *dev)
331 {
332 struct emc2305_data *data = dev_get_drvdata(dev);
333 int i, ret;
334
335 if (!data->pwm_separate)
336 return emc2305_set_single_tz(dev, 0);
337
338 for (i = 0; i < data->pwm_num; i++) {
339 ret = emc2305_set_single_tz(dev, i + 1);
340 if (ret)
341 goto thermal_cooling_device_register_fail;
342 }
343 return 0;
344
345 thermal_cooling_device_register_fail:
346 emc2305_unset_tz(dev);
347 return ret;
348 }
349
emc2305_unset_tz(struct device * dev)350 static void emc2305_unset_tz(struct device *dev)
351 {
352 struct emc2305_data *data = dev_get_drvdata(dev);
353 int i;
354
355 /* Unregister cooling device. */
356 for (i = 0; i < EMC2305_PWM_MAX; i++)
357 if (data->cdev_data[i].cdev)
358 thermal_cooling_device_unregister(data->cdev_data[i].cdev);
359 }
360
361 static umode_t
emc2305_is_visible(const void * data,enum hwmon_sensor_types type,u32 attr,int channel)362 emc2305_is_visible(const void *data, enum hwmon_sensor_types type, u32 attr, int channel)
363 {
364 int max_channel = emc2305_get_max_channel(data);
365
366 /* Don't show channels which are not physically connected. */
367 if (channel >= max_channel)
368 return 0;
369 switch (type) {
370 case hwmon_fan:
371 switch (attr) {
372 case hwmon_fan_input:
373 return 0444;
374 case hwmon_fan_fault:
375 return 0444;
376 default:
377 break;
378 }
379 break;
380 case hwmon_pwm:
381 switch (attr) {
382 case hwmon_pwm_input:
383 return 0644;
384 default:
385 break;
386 }
387 break;
388 default:
389 break;
390 }
391
392 return 0;
393 };
394
395 static int
emc2305_write(struct device * dev,enum hwmon_sensor_types type,u32 attr,int channel,long val)396 emc2305_write(struct device *dev, enum hwmon_sensor_types type, u32 attr, int channel, long val)
397 {
398 struct emc2305_data *data = dev_get_drvdata(dev);
399 int cdev_idx;
400
401 switch (type) {
402 case hwmon_pwm:
403 switch (attr) {
404 case hwmon_pwm_input:
405 /* If thermal is configured - handle PWM limit setting. */
406 if (IS_REACHABLE(CONFIG_THERMAL)) {
407 if (data->pwm_separate)
408 cdev_idx = channel;
409 else
410 cdev_idx = 0;
411 data->cdev_data[cdev_idx].last_hwmon_state =
412 EMC2305_PWM_DUTY2STATE(val, data->max_state,
413 EMC2305_FAN_MAX);
414 /*
415 * Update PWM only in case requested state is not less than the
416 * last thermal state.
417 */
418 if (data->cdev_data[cdev_idx].last_hwmon_state >=
419 data->cdev_data[cdev_idx].last_thermal_state)
420 return __emc2305_set_cur_state(data, cdev_idx,
421 data->cdev_data[cdev_idx].last_hwmon_state);
422 return 0;
423 }
424 return emc2305_set_pwm(dev, val, channel);
425 default:
426 break;
427 }
428 break;
429 default:
430 break;
431 }
432
433 return -EOPNOTSUPP;
434 };
435
436 static int
emc2305_read(struct device * dev,enum hwmon_sensor_types type,u32 attr,int channel,long * val)437 emc2305_read(struct device *dev, enum hwmon_sensor_types type, u32 attr, int channel, long *val)
438 {
439 int ret;
440
441 switch (type) {
442 case hwmon_fan:
443 switch (attr) {
444 case hwmon_fan_input:
445 ret = emc2305_show_fan(dev, channel);
446 if (ret < 0)
447 return ret;
448 *val = ret;
449 return 0;
450 case hwmon_fan_fault:
451 ret = emc2305_show_fault(dev, channel);
452 if (ret < 0)
453 return ret;
454 *val = ret;
455 return 0;
456 default:
457 break;
458 }
459 break;
460 case hwmon_pwm:
461 switch (attr) {
462 case hwmon_pwm_input:
463 ret = emc2305_show_pwm(dev, channel);
464 if (ret < 0)
465 return ret;
466 *val = ret;
467 return 0;
468 default:
469 break;
470 }
471 break;
472 default:
473 break;
474 }
475
476 return -EOPNOTSUPP;
477 };
478
479 static const struct hwmon_ops emc2305_ops = {
480 .is_visible = emc2305_is_visible,
481 .read = emc2305_read,
482 .write = emc2305_write,
483 };
484
485 static const struct hwmon_channel_info * const emc2305_info[] = {
486 HWMON_CHANNEL_INFO(fan,
487 HWMON_F_INPUT | HWMON_F_FAULT,
488 HWMON_F_INPUT | HWMON_F_FAULT,
489 HWMON_F_INPUT | HWMON_F_FAULT,
490 HWMON_F_INPUT | HWMON_F_FAULT,
491 HWMON_F_INPUT | HWMON_F_FAULT),
492 HWMON_CHANNEL_INFO(pwm,
493 HWMON_PWM_INPUT,
494 HWMON_PWM_INPUT,
495 HWMON_PWM_INPUT,
496 HWMON_PWM_INPUT,
497 HWMON_PWM_INPUT),
498 NULL
499 };
500
501 static const struct hwmon_chip_info emc2305_chip_info = {
502 .ops = &emc2305_ops,
503 .info = emc2305_info,
504 };
505
emc2305_identify(struct device * dev)506 static int emc2305_identify(struct device *dev)
507 {
508 struct i2c_client *client = to_i2c_client(dev);
509 struct emc2305_data *data = i2c_get_clientdata(client);
510 int ret;
511
512 ret = i2c_smbus_read_byte_data(client, EMC2305_REG_PRODUCT_ID);
513 if (ret < 0)
514 return ret;
515
516 switch (ret) {
517 case EMC2305:
518 data->pwm_num = 5;
519 break;
520 case EMC2303:
521 data->pwm_num = 3;
522 break;
523 case EMC2302:
524 data->pwm_num = 2;
525 break;
526 case EMC2301:
527 data->pwm_num = 1;
528 break;
529 default:
530 return -ENODEV;
531 }
532
533 return 0;
534 }
535
emc2305_probe(struct i2c_client * client)536 static int emc2305_probe(struct i2c_client *client)
537 {
538 struct i2c_adapter *adapter = client->adapter;
539 struct device *dev = &client->dev;
540 struct emc2305_data *data;
541 struct emc2305_platform_data *pdata;
542 int vendor;
543 int ret;
544 int i;
545
546 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA))
547 return -ENODEV;
548
549 vendor = i2c_smbus_read_byte_data(client, EMC2305_REG_VENDOR);
550 if (vendor != EMC2305_VENDOR)
551 return -ENODEV;
552
553 data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
554 if (!data)
555 return -ENOMEM;
556
557 i2c_set_clientdata(client, data);
558 data->client = client;
559
560 ret = emc2305_identify(dev);
561 if (ret)
562 return ret;
563
564 pdata = dev_get_platdata(&client->dev);
565 if (pdata) {
566 if (!pdata->max_state || pdata->max_state > EMC2305_FAN_MAX_STATE)
567 return -EINVAL;
568 data->max_state = pdata->max_state;
569 /*
570 * Validate a number of active PWM channels. Note that
571 * configured number can be less than the actual maximum
572 * supported by the device.
573 */
574 if (!pdata->pwm_num || pdata->pwm_num > EMC2305_PWM_MAX)
575 return -EINVAL;
576 data->pwm_num = pdata->pwm_num;
577 data->pwm_separate = pdata->pwm_separate;
578 for (i = 0; i < EMC2305_PWM_MAX; i++)
579 data->pwm_min[i] = pdata->pwm_min[i];
580 } else {
581 data->max_state = EMC2305_FAN_MAX_STATE;
582 data->pwm_separate = false;
583 for (i = 0; i < EMC2305_PWM_MAX; i++)
584 data->pwm_min[i] = EMC2305_FAN_MIN;
585 }
586
587 data->hwmon_dev = devm_hwmon_device_register_with_info(dev, "emc2305", data,
588 &emc2305_chip_info, NULL);
589 if (IS_ERR(data->hwmon_dev))
590 return PTR_ERR(data->hwmon_dev);
591
592 if (IS_REACHABLE(CONFIG_THERMAL)) {
593 ret = emc2305_set_tz(dev);
594 if (ret != 0)
595 return ret;
596 }
597
598 for (i = 0; i < data->pwm_num; i++) {
599 ret = i2c_smbus_write_byte_data(client, EMC2305_REG_FAN_MIN_DRIVE(i),
600 data->pwm_min[i]);
601 if (ret < 0)
602 return ret;
603 }
604
605 return 0;
606 }
607
emc2305_remove(struct i2c_client * client)608 static void emc2305_remove(struct i2c_client *client)
609 {
610 struct device *dev = &client->dev;
611
612 if (IS_REACHABLE(CONFIG_THERMAL))
613 emc2305_unset_tz(dev);
614 }
615
616 static struct i2c_driver emc2305_driver = {
617 .driver = {
618 .name = "emc2305",
619 },
620 .probe = emc2305_probe,
621 .remove = emc2305_remove,
622 .id_table = emc2305_ids,
623 };
624
625 module_i2c_driver(emc2305_driver);
626
627 MODULE_AUTHOR("Nvidia");
628 MODULE_DESCRIPTION("Microchip EMC2305 fan controller driver");
629 MODULE_LICENSE("GPL");
630