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
42enum emc230x_product_id {
43 EMC2305 = 0x34,
44 EMC2303 = 0x35,
45 EMC2302 = 0x36,
46 EMC2301 = 0x37,
47};
48
49static const struct i2c_device_id emc2305_ids[] = {
50 { "emc2305", 0 },
51 { "emc2303", 0 },
52 { "emc2302", 0 },
53 { "emc2301", 0 },
54 { }
55};
56MODULE_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 */
79struct 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 */
96struct 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
106static char *emc2305_fan_name[] = {
107 "emc2305_fan",
108 "emc2305_fan1",
109 "emc2305_fan2",
110 "emc2305_fan3",
111 "emc2305_fan4",
112 "emc2305_fan5",
113};
114
115static void emc2305_unset_tz(struct device *dev);
116
117static int emc2305_get_max_channel(const struct emc2305_data *data)
118{
119 return data->pwm_num;
120}
121
122static 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
153static 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
166static 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
173static 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), value: 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), value: val);
195 if (ret < 0)
196 return ret;
197 }
198 }
199
200 return 0;
201}
202
203static 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
224static 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
230static 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
243static 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
261static 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
269static 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), value: 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
286static 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(ptr: 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(ptr: data->cdev_data[cdev_idx].cdev);
302 }
303 /* Set minimal PWM speed. */
304 if (data->pwm_separate) {
305 ret = emc2305_set_pwm(dev, val: pwm, channel: cdev_idx);
306 if (ret < 0)
307 return ret;
308 } else {
309 for (i = 0; i < data->pwm_num; i++) {
310 ret = emc2305_set_pwm(dev, val: pwm, channel: i);
311 if (ret < 0)
312 return ret;
313 }
314 }
315 data->cdev_data[cdev_idx].cur_state =
316 EMC2305_PWM_DUTY2STATE(data->pwm_min[cdev_idx], data->max_state,
317 EMC2305_FAN_MAX);
318 data->cdev_data[cdev_idx].last_hwmon_state =
319 EMC2305_PWM_DUTY2STATE(data->pwm_min[cdev_idx], data->max_state,
320 EMC2305_FAN_MAX);
321 return 0;
322}
323
324static int emc2305_set_tz(struct device *dev)
325{
326 struct emc2305_data *data = dev_get_drvdata(dev);
327 int i, ret;
328
329 if (!data->pwm_separate)
330 return emc2305_set_single_tz(dev, idx: 0);
331
332 for (i = 0; i < data->pwm_num; i++) {
333 ret = emc2305_set_single_tz(dev, idx: i + 1);
334 if (ret)
335 goto thermal_cooling_device_register_fail;
336 }
337 return 0;
338
339thermal_cooling_device_register_fail:
340 emc2305_unset_tz(dev);
341 return ret;
342}
343
344static void emc2305_unset_tz(struct device *dev)
345{
346 struct emc2305_data *data = dev_get_drvdata(dev);
347 int i;
348
349 /* Unregister cooling device. */
350 for (i = 0; i < EMC2305_PWM_MAX; i++)
351 if (data->cdev_data[i].cdev)
352 thermal_cooling_device_unregister(data->cdev_data[i].cdev);
353}
354
355static umode_t
356emc2305_is_visible(const void *data, enum hwmon_sensor_types type, u32 attr, int channel)
357{
358 int max_channel = emc2305_get_max_channel(data);
359
360 /* Don't show channels which are not physically connected. */
361 if (channel >= max_channel)
362 return 0;
363 switch (type) {
364 case hwmon_fan:
365 switch (attr) {
366 case hwmon_fan_input:
367 return 0444;
368 case hwmon_fan_fault:
369 return 0444;
370 default:
371 break;
372 }
373 break;
374 case hwmon_pwm:
375 switch (attr) {
376 case hwmon_pwm_input:
377 return 0644;
378 default:
379 break;
380 }
381 break;
382 default:
383 break;
384 }
385
386 return 0;
387};
388
389static int
390emc2305_write(struct device *dev, enum hwmon_sensor_types type, u32 attr, int channel, long val)
391{
392 struct emc2305_data *data = dev_get_drvdata(dev);
393 int cdev_idx;
394
395 switch (type) {
396 case hwmon_pwm:
397 switch (attr) {
398 case hwmon_pwm_input:
399 /* If thermal is configured - handle PWM limit setting. */
400 if (IS_REACHABLE(CONFIG_THERMAL)) {
401 if (data->pwm_separate)
402 cdev_idx = channel;
403 else
404 cdev_idx = 0;
405 data->cdev_data[cdev_idx].last_hwmon_state =
406 EMC2305_PWM_DUTY2STATE(val, data->max_state,
407 EMC2305_FAN_MAX);
408 /*
409 * Update PWM only in case requested state is not less than the
410 * last thermal state.
411 */
412 if (data->cdev_data[cdev_idx].last_hwmon_state >=
413 data->cdev_data[cdev_idx].last_thermal_state)
414 return __emc2305_set_cur_state(data, cdev_idx,
415 state: data->cdev_data[cdev_idx].last_hwmon_state);
416 return 0;
417 }
418 return emc2305_set_pwm(dev, val, channel);
419 default:
420 break;
421 }
422 break;
423 default:
424 break;
425 }
426
427 return -EOPNOTSUPP;
428};
429
430static int
431emc2305_read(struct device *dev, enum hwmon_sensor_types type, u32 attr, int channel, long *val)
432{
433 int ret;
434
435 switch (type) {
436 case hwmon_fan:
437 switch (attr) {
438 case hwmon_fan_input:
439 ret = emc2305_show_fan(dev, channel);
440 if (ret < 0)
441 return ret;
442 *val = ret;
443 return 0;
444 case hwmon_fan_fault:
445 ret = emc2305_show_fault(dev, channel);
446 if (ret < 0)
447 return ret;
448 *val = ret;
449 return 0;
450 default:
451 break;
452 }
453 break;
454 case hwmon_pwm:
455 switch (attr) {
456 case hwmon_pwm_input:
457 ret = emc2305_show_pwm(dev, channel);
458 if (ret < 0)
459 return ret;
460 *val = ret;
461 return 0;
462 default:
463 break;
464 }
465 break;
466 default:
467 break;
468 }
469
470 return -EOPNOTSUPP;
471};
472
473static const struct hwmon_ops emc2305_ops = {
474 .is_visible = emc2305_is_visible,
475 .read = emc2305_read,
476 .write = emc2305_write,
477};
478
479static const struct hwmon_channel_info * const emc2305_info[] = {
480 HWMON_CHANNEL_INFO(fan,
481 HWMON_F_INPUT | HWMON_F_FAULT,
482 HWMON_F_INPUT | HWMON_F_FAULT,
483 HWMON_F_INPUT | HWMON_F_FAULT,
484 HWMON_F_INPUT | HWMON_F_FAULT,
485 HWMON_F_INPUT | HWMON_F_FAULT),
486 HWMON_CHANNEL_INFO(pwm,
487 HWMON_PWM_INPUT,
488 HWMON_PWM_INPUT,
489 HWMON_PWM_INPUT,
490 HWMON_PWM_INPUT,
491 HWMON_PWM_INPUT),
492 NULL
493};
494
495static const struct hwmon_chip_info emc2305_chip_info = {
496 .ops = &emc2305_ops,
497 .info = emc2305_info,
498};
499
500static int emc2305_identify(struct device *dev)
501{
502 struct i2c_client *client = to_i2c_client(dev);
503 struct emc2305_data *data = i2c_get_clientdata(client);
504 int ret;
505
506 ret = i2c_smbus_read_byte_data(client, EMC2305_REG_PRODUCT_ID);
507 if (ret < 0)
508 return ret;
509
510 switch (ret) {
511 case EMC2305:
512 data->pwm_num = 5;
513 break;
514 case EMC2303:
515 data->pwm_num = 3;
516 break;
517 case EMC2302:
518 data->pwm_num = 2;
519 break;
520 case EMC2301:
521 data->pwm_num = 1;
522 break;
523 default:
524 return -ENODEV;
525 }
526
527 return 0;
528}
529
530static int emc2305_probe(struct i2c_client *client)
531{
532 struct i2c_adapter *adapter = client->adapter;
533 struct device *dev = &client->dev;
534 struct emc2305_data *data;
535 struct emc2305_platform_data *pdata;
536 int vendor;
537 int ret;
538 int i;
539
540 if (!i2c_check_functionality(adap: adapter, I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA))
541 return -ENODEV;
542
543 vendor = i2c_smbus_read_byte_data(client, EMC2305_REG_VENDOR);
544 if (vendor != EMC2305_VENDOR)
545 return -ENODEV;
546
547 data = devm_kzalloc(dev, size: sizeof(*data), GFP_KERNEL);
548 if (!data)
549 return -ENOMEM;
550
551 i2c_set_clientdata(client, data);
552 data->client = client;
553
554 ret = emc2305_identify(dev);
555 if (ret)
556 return ret;
557
558 pdata = dev_get_platdata(dev: &client->dev);
559 if (pdata) {
560 if (!pdata->max_state || pdata->max_state > EMC2305_FAN_MAX_STATE)
561 return -EINVAL;
562 data->max_state = pdata->max_state;
563 /*
564 * Validate a number of active PWM channels. Note that
565 * configured number can be less than the actual maximum
566 * supported by the device.
567 */
568 if (!pdata->pwm_num || pdata->pwm_num > EMC2305_PWM_MAX)
569 return -EINVAL;
570 data->pwm_num = pdata->pwm_num;
571 data->pwm_separate = pdata->pwm_separate;
572 for (i = 0; i < EMC2305_PWM_MAX; i++)
573 data->pwm_min[i] = pdata->pwm_min[i];
574 } else {
575 data->max_state = EMC2305_FAN_MAX_STATE;
576 data->pwm_separate = false;
577 for (i = 0; i < EMC2305_PWM_MAX; i++)
578 data->pwm_min[i] = EMC2305_FAN_MIN;
579 }
580
581 data->hwmon_dev = devm_hwmon_device_register_with_info(dev, name: "emc2305", drvdata: data,
582 info: &emc2305_chip_info, NULL);
583 if (IS_ERR(ptr: data->hwmon_dev))
584 return PTR_ERR(ptr: data->hwmon_dev);
585
586 if (IS_REACHABLE(CONFIG_THERMAL)) {
587 ret = emc2305_set_tz(dev);
588 if (ret != 0)
589 return ret;
590 }
591
592 for (i = 0; i < data->pwm_num; i++) {
593 ret = i2c_smbus_write_byte_data(client, EMC2305_REG_FAN_MIN_DRIVE(i),
594 value: data->pwm_min[i]);
595 if (ret < 0)
596 return ret;
597 }
598
599 return 0;
600}
601
602static void emc2305_remove(struct i2c_client *client)
603{
604 struct device *dev = &client->dev;
605
606 if (IS_REACHABLE(CONFIG_THERMAL))
607 emc2305_unset_tz(dev);
608}
609
610static struct i2c_driver emc2305_driver = {
611 .driver = {
612 .name = "emc2305",
613 },
614 .probe = emc2305_probe,
615 .remove = emc2305_remove,
616 .id_table = emc2305_ids,
617};
618
619module_i2c_driver(emc2305_driver);
620
621MODULE_AUTHOR("Nvidia");
622MODULE_DESCRIPTION("Microchip EMC2305 fan controller driver");
623MODULE_LICENSE("GPL");
624

source code of linux/drivers/hwmon/emc2305.c