1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * max6650.c - Part of lm_sensors, Linux kernel modules for hardware
6 * (C) 2007 by Hans J. Koch <hjk@hansjkoch.de>
8 * based on code written by John Morris <john.morris@spirentcom.com>
9 * Copyright (c) 2003 Spirent Communications
10 * and Claus Gindhart <claus.gindhart@kontron.com>
12 * This module has only been tested with the MAX6650 chip. It should
13 * also work with the MAX6651. It does not distinguish max6650 and max6651
16 * The datasheet was last seen at:
18 * http://pdfserv.maxim-ic.com/en/ds/MAX6650-MAX6651.pdf
21 #include <linux/module.h>
22 #include <linux/init.h>
23 #include <linux/slab.h>
24 #include <linux/jiffies.h>
25 #include <linux/i2c.h>
26 #include <linux/hwmon.h>
27 #include <linux/hwmon-sysfs.h>
28 #include <linux/err.h>
29 #include <linux/of_device.h>
30 #include <linux/thermal.h>
36 /* fan_voltage: 5=5V fan, 12=12V fan, 0=don't change */
37 static int fan_voltage;
38 /* prescaler: Possible values are 1, 2, 4, 8, 16 or 0 for don't change */
40 /* clock: The clock frequency of the chip (max6651 can be clocked externally) */
41 static int clock = 254000;
43 module_param(fan_voltage, int, 0444);
44 module_param(prescaler, int, 0444);
45 module_param(clock, int, 0444);
48 * MAX 6650/6651 registers
51 #define MAX6650_REG_SPEED 0x00
52 #define MAX6650_REG_CONFIG 0x02
53 #define MAX6650_REG_GPIO_DEF 0x04
54 #define MAX6650_REG_DAC 0x06
55 #define MAX6650_REG_ALARM_EN 0x08
56 #define MAX6650_REG_ALARM 0x0A
57 #define MAX6650_REG_TACH0 0x0C
58 #define MAX6650_REG_TACH1 0x0E
59 #define MAX6650_REG_TACH2 0x10
60 #define MAX6650_REG_TACH3 0x12
61 #define MAX6650_REG_GPIO_STAT 0x14
62 #define MAX6650_REG_COUNT 0x16
65 * Config register bits
68 #define MAX6650_CFG_V12 0x08
69 #define MAX6650_CFG_PRESCALER_MASK 0x07
70 #define MAX6650_CFG_PRESCALER_2 0x01
71 #define MAX6650_CFG_PRESCALER_4 0x02
72 #define MAX6650_CFG_PRESCALER_8 0x03
73 #define MAX6650_CFG_PRESCALER_16 0x04
74 #define MAX6650_CFG_MODE_MASK 0x30
75 #define MAX6650_CFG_MODE_ON 0x00
76 #define MAX6650_CFG_MODE_OFF 0x10
77 #define MAX6650_CFG_MODE_CLOSED_LOOP 0x20
78 #define MAX6650_CFG_MODE_OPEN_LOOP 0x30
79 #define MAX6650_COUNT_MASK 0x03
82 * Alarm status register bits
85 #define MAX6650_ALRM_MAX 0x01
86 #define MAX6650_ALRM_MIN 0x02
87 #define MAX6650_ALRM_TACH 0x04
88 #define MAX6650_ALRM_GPIO1 0x08
89 #define MAX6650_ALRM_GPIO2 0x10
91 /* Minimum and maximum values of the FAN-RPM */
92 #define FAN_RPM_MIN 240
93 #define FAN_RPM_MAX 30000
95 #define DIV_FROM_REG(reg) (1 << (reg & 7))
98 * Client data (each client gets its own)
101 struct max6650_data {
102 struct i2c_client *client;
103 const struct attribute_group *groups[3];
104 struct thermal_cooling_device *cooling_dev;
105 struct mutex update_lock;
107 char valid; /* zero until following fields are valid */
108 unsigned long last_updated; /* in jiffies */
110 /* register values */
117 unsigned long cooling_dev_state;
120 static const u8 tach_reg[] = {
127 static const struct of_device_id __maybe_unused max6650_dt_match[] = {
129 .compatible = "maxim,max6650",
133 .compatible = "maxim,max6651",
138 MODULE_DEVICE_TABLE(of, max6650_dt_match);
140 static struct max6650_data *max6650_update_device(struct device *dev)
142 struct max6650_data *data = dev_get_drvdata(dev);
143 struct i2c_client *client = data->client;
146 mutex_lock(&data->update_lock);
148 if (time_after(jiffies, data->last_updated + HZ) || !data->valid) {
149 data->speed = i2c_smbus_read_byte_data(client,
151 data->config = i2c_smbus_read_byte_data(client,
153 for (i = 0; i < data->nr_fans; i++) {
154 data->tach[i] = i2c_smbus_read_byte_data(client,
157 data->count = i2c_smbus_read_byte_data(client,
159 data->dac = i2c_smbus_read_byte_data(client, MAX6650_REG_DAC);
162 * Alarms are cleared on read in case the condition that
163 * caused the alarm is removed. Keep the value latched here
164 * for providing the register through different alarm files.
166 data->alarm |= i2c_smbus_read_byte_data(client,
169 data->last_updated = jiffies;
173 mutex_unlock(&data->update_lock);
179 * Change the operating mode of the chip (if needed).
180 * mode is one of the MAX6650_CFG_MODE_* values.
182 static int max6650_set_operating_mode(struct max6650_data *data, u8 mode)
185 u8 config = data->config;
187 if (mode == (config & MAX6650_CFG_MODE_MASK))
190 config = (config & ~MAX6650_CFG_MODE_MASK) | mode;
192 result = i2c_smbus_write_byte_data(data->client, MAX6650_REG_CONFIG,
197 data->config = config;
202 static ssize_t fan_show(struct device *dev, struct device_attribute *devattr,
205 struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
206 struct max6650_data *data = max6650_update_device(dev);
210 * Calculation details:
212 * Each tachometer counts over an interval given by the "count"
213 * register (0.25, 0.5, 1 or 2 seconds). This module assumes
214 * that the fans produce two pulses per revolution (this seems
215 * to be the most common).
218 rpm = ((data->tach[attr->index] * 120) / DIV_FROM_REG(data->count));
219 return sprintf(buf, "%d\n", rpm);
223 * Set the fan speed to the specified RPM (or read back the RPM setting).
224 * This works in closed loop mode only. Use pwm1 for open loop speed setting.
226 * The MAX6650/1 will automatically control fan speed when in closed loop
231 * 1) The MAX6650/1 internal 254kHz clock frequency is set correctly. Use
232 * the clock module parameter if you need to fine tune this.
234 * 2) The prescaler (low three bits of the config register) has already
235 * been set to an appropriate value. Use the prescaler module parameter
236 * if your BIOS doesn't initialize the chip properly.
238 * The relevant equations are given on pages 21 and 22 of the datasheet.
240 * From the datasheet, the relevant equation when in regulation is:
242 * [fCLK / (128 x (KTACH + 1))] = 2 x FanSpeed / KSCALE
246 * fCLK is the oscillator frequency (either the 254kHz internal
247 * oscillator or the externally applied clock)
249 * KTACH is the value in the speed register
251 * FanSpeed is the speed of the fan in rps
253 * KSCALE is the prescaler value (1, 2, 4, 8, or 16)
255 * When reading, we need to solve for FanSpeed. When writing, we need to
258 * Note: this tachometer is completely separate from the tachometers
259 * used to measure the fan speeds. Only one fan's speed (fan1) is
263 static ssize_t fan1_target_show(struct device *dev,
264 struct device_attribute *devattr, char *buf)
266 struct max6650_data *data = max6650_update_device(dev);
267 int kscale, ktach, rpm;
270 * Use the datasheet equation:
272 * FanSpeed = KSCALE x fCLK / [256 x (KTACH + 1)]
274 * then multiply by 60 to give rpm.
277 kscale = DIV_FROM_REG(data->config);
279 rpm = 60 * kscale * clock / (256 * (ktach + 1));
280 return sprintf(buf, "%d\n", rpm);
283 static int max6650_set_target(struct max6650_data *data, unsigned long rpm)
288 return max6650_set_operating_mode(data, MAX6650_CFG_MODE_OFF);
290 rpm = clamp_val(rpm, FAN_RPM_MIN, FAN_RPM_MAX);
293 * Divide the required speed by 60 to get from rpm to rps, then
294 * use the datasheet equation:
296 * KTACH = [(fCLK x KSCALE) / (256 x FanSpeed)] - 1
299 kscale = DIV_FROM_REG(data->config);
300 ktach = ((clock * kscale) / (256 * rpm / 60)) - 1;
307 return i2c_smbus_write_byte_data(data->client, MAX6650_REG_SPEED,
311 static ssize_t fan1_target_store(struct device *dev,
312 struct device_attribute *devattr,
313 const char *buf, size_t count)
315 struct max6650_data *data = dev_get_drvdata(dev);
319 err = kstrtoul(buf, 10, &rpm);
323 mutex_lock(&data->update_lock);
325 err = max6650_set_target(data, rpm);
327 mutex_unlock(&data->update_lock);
336 * Get/set the fan speed in open loop mode using pwm1 sysfs file.
337 * Speed is given as a relative value from 0 to 255, where 255 is maximum
338 * speed. Note that this is done by writing directly to the chip's DAC,
339 * it won't change the closed loop speed set by fan1_target.
340 * Also note that due to rounding errors it is possible that you don't read
341 * back exactly the value you have set.
344 static ssize_t pwm1_show(struct device *dev, struct device_attribute *devattr,
348 struct max6650_data *data = max6650_update_device(dev);
351 * Useful range for dac is 0-180 for 12V fans and 0-76 for 5V fans.
352 * Lower DAC values mean higher speeds.
354 if (data->config & MAX6650_CFG_V12)
355 pwm = 255 - (255 * (int)data->dac)/180;
357 pwm = 255 - (255 * (int)data->dac)/76;
362 return sprintf(buf, "%d\n", pwm);
365 static ssize_t pwm1_store(struct device *dev,
366 struct device_attribute *devattr, const char *buf,
369 struct max6650_data *data = dev_get_drvdata(dev);
370 struct i2c_client *client = data->client;
374 err = kstrtoul(buf, 10, &pwm);
378 pwm = clamp_val(pwm, 0, 255);
380 mutex_lock(&data->update_lock);
382 if (data->config & MAX6650_CFG_V12)
383 data->dac = 180 - (180 * pwm)/255;
385 data->dac = 76 - (76 * pwm)/255;
386 err = i2c_smbus_write_byte_data(client, MAX6650_REG_DAC, data->dac);
388 mutex_unlock(&data->update_lock);
390 return err < 0 ? err : count;
394 * Get/Set controller mode:
397 * 1 = Open loop, Voltage is set according to speed, not regulated.
398 * 2 = Closed loop, RPM for all fans regulated by fan1 tachometer
401 static ssize_t pwm1_enable_show(struct device *dev,
402 struct device_attribute *devattr, char *buf)
404 struct max6650_data *data = max6650_update_device(dev);
405 int mode = (data->config & MAX6650_CFG_MODE_MASK) >> 4;
406 int sysfs_modes[4] = {0, 3, 2, 1};
408 return sprintf(buf, "%d\n", sysfs_modes[mode]);
411 static ssize_t pwm1_enable_store(struct device *dev,
412 struct device_attribute *devattr,
413 const char *buf, size_t count)
415 struct max6650_data *data = dev_get_drvdata(dev);
418 const u8 max6650_modes[] = {
420 MAX6650_CFG_MODE_OPEN_LOOP,
421 MAX6650_CFG_MODE_CLOSED_LOOP,
422 MAX6650_CFG_MODE_OFF,
425 err = kstrtoul(buf, 10, &mode);
429 if (mode >= ARRAY_SIZE(max6650_modes))
432 mutex_lock(&data->update_lock);
434 max6650_set_operating_mode(data, max6650_modes[mode]);
436 mutex_unlock(&data->update_lock);
442 * Read/write functions for fan1_div sysfs file. The MAX6650 has no such
443 * divider. We handle this by converting between divider and counttime:
445 * (counttime == k) <==> (divider == 2^k), k = 0, 1, 2, or 3
447 * Lower values of k allow to connect a faster fan without the risk of
448 * counter overflow. The price is lower resolution. You can also set counttime
449 * using the module parameter. Note that the module parameter "prescaler" also
450 * influences the behaviour. Unfortunately, there's no sysfs attribute
451 * defined for that. See the data sheet for details.
454 static ssize_t fan1_div_show(struct device *dev,
455 struct device_attribute *devattr, char *buf)
457 struct max6650_data *data = max6650_update_device(dev);
459 return sprintf(buf, "%d\n", DIV_FROM_REG(data->count));
462 static ssize_t fan1_div_store(struct device *dev,
463 struct device_attribute *devattr,
464 const char *buf, size_t count)
466 struct max6650_data *data = dev_get_drvdata(dev);
467 struct i2c_client *client = data->client;
471 err = kstrtoul(buf, 10, &div);
475 mutex_lock(&data->update_lock);
490 mutex_unlock(&data->update_lock);
494 i2c_smbus_write_byte_data(client, MAX6650_REG_COUNT, data->count);
495 mutex_unlock(&data->update_lock);
507 static ssize_t alarm_show(struct device *dev,
508 struct device_attribute *devattr, char *buf)
510 struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
511 struct max6650_data *data = max6650_update_device(dev);
512 struct i2c_client *client = data->client;
515 if (data->alarm & attr->index) {
516 mutex_lock(&data->update_lock);
518 data->alarm &= ~attr->index;
519 data->alarm |= i2c_smbus_read_byte_data(client,
521 mutex_unlock(&data->update_lock);
524 return sprintf(buf, "%d\n", alarm);
527 static SENSOR_DEVICE_ATTR_RO(fan1_input, fan, 0);
528 static SENSOR_DEVICE_ATTR_RO(fan2_input, fan, 1);
529 static SENSOR_DEVICE_ATTR_RO(fan3_input, fan, 2);
530 static SENSOR_DEVICE_ATTR_RO(fan4_input, fan, 3);
531 static DEVICE_ATTR_RW(fan1_target);
532 static DEVICE_ATTR_RW(fan1_div);
533 static DEVICE_ATTR_RW(pwm1_enable);
534 static DEVICE_ATTR_RW(pwm1);
535 static SENSOR_DEVICE_ATTR_RO(fan1_max_alarm, alarm, MAX6650_ALRM_MAX);
536 static SENSOR_DEVICE_ATTR_RO(fan1_min_alarm, alarm, MAX6650_ALRM_MIN);
537 static SENSOR_DEVICE_ATTR_RO(fan1_fault, alarm, MAX6650_ALRM_TACH);
538 static SENSOR_DEVICE_ATTR_RO(gpio1_alarm, alarm, MAX6650_ALRM_GPIO1);
539 static SENSOR_DEVICE_ATTR_RO(gpio2_alarm, alarm, MAX6650_ALRM_GPIO2);
541 static umode_t max6650_attrs_visible(struct kobject *kobj, struct attribute *a,
544 struct device *dev = container_of(kobj, struct device, kobj);
545 struct max6650_data *data = dev_get_drvdata(dev);
546 struct i2c_client *client = data->client;
547 u8 alarm_en = i2c_smbus_read_byte_data(client, MAX6650_REG_ALARM_EN);
548 struct device_attribute *devattr;
551 * Hide the alarms that have not been enabled by the firmware
554 devattr = container_of(a, struct device_attribute, attr);
555 if (devattr == &sensor_dev_attr_fan1_max_alarm.dev_attr
556 || devattr == &sensor_dev_attr_fan1_min_alarm.dev_attr
557 || devattr == &sensor_dev_attr_fan1_fault.dev_attr
558 || devattr == &sensor_dev_attr_gpio1_alarm.dev_attr
559 || devattr == &sensor_dev_attr_gpio2_alarm.dev_attr) {
560 if (!(alarm_en & to_sensor_dev_attr(devattr)->index))
567 static struct attribute *max6650_attrs[] = {
568 &sensor_dev_attr_fan1_input.dev_attr.attr,
569 &dev_attr_fan1_target.attr,
570 &dev_attr_fan1_div.attr,
571 &dev_attr_pwm1_enable.attr,
573 &sensor_dev_attr_fan1_max_alarm.dev_attr.attr,
574 &sensor_dev_attr_fan1_min_alarm.dev_attr.attr,
575 &sensor_dev_attr_fan1_fault.dev_attr.attr,
576 &sensor_dev_attr_gpio1_alarm.dev_attr.attr,
577 &sensor_dev_attr_gpio2_alarm.dev_attr.attr,
581 static const struct attribute_group max6650_group = {
582 .attrs = max6650_attrs,
583 .is_visible = max6650_attrs_visible,
586 static struct attribute *max6651_attrs[] = {
587 &sensor_dev_attr_fan2_input.dev_attr.attr,
588 &sensor_dev_attr_fan3_input.dev_attr.attr,
589 &sensor_dev_attr_fan4_input.dev_attr.attr,
593 static const struct attribute_group max6651_group = {
594 .attrs = max6651_attrs,
601 static int max6650_init_client(struct max6650_data *data,
602 struct i2c_client *client)
604 struct device *dev = &client->dev;
611 if (of_property_read_u32(dev->of_node, "maxim,fan-microvolt",
613 voltage = fan_voltage;
615 voltage /= 1000000; /* Microvolts to volts */
616 if (of_property_read_u32(dev->of_node, "maxim,fan-prescale",
618 prescale = prescaler;
620 config = i2c_smbus_read_byte_data(client, MAX6650_REG_CONFIG);
623 dev_err(dev, "Error reading config, aborting.\n");
631 config &= ~MAX6650_CFG_V12;
634 config |= MAX6650_CFG_V12;
637 dev_err(dev, "illegal value for fan_voltage (%d)\n", voltage);
644 config &= ~MAX6650_CFG_PRESCALER_MASK;
647 config = (config & ~MAX6650_CFG_PRESCALER_MASK)
648 | MAX6650_CFG_PRESCALER_2;
651 config = (config & ~MAX6650_CFG_PRESCALER_MASK)
652 | MAX6650_CFG_PRESCALER_4;
655 config = (config & ~MAX6650_CFG_PRESCALER_MASK)
656 | MAX6650_CFG_PRESCALER_8;
659 config = (config & ~MAX6650_CFG_PRESCALER_MASK)
660 | MAX6650_CFG_PRESCALER_16;
663 dev_err(dev, "illegal value for prescaler (%d)\n", prescale);
666 dev_info(dev, "Fan voltage: %dV, prescaler: %d.\n",
667 (config & MAX6650_CFG_V12) ? 12 : 5,
668 1 << (config & MAX6650_CFG_PRESCALER_MASK));
670 if (i2c_smbus_write_byte_data(client, MAX6650_REG_CONFIG, config)) {
671 dev_err(dev, "Config write error, aborting.\n");
675 data->config = config;
676 data->count = i2c_smbus_read_byte_data(client, MAX6650_REG_COUNT);
678 if (!of_property_read_u32(client->dev.of_node, "maxim,fan-target-rpm",
680 max6650_set_target(data, target_rpm);
681 max6650_set_operating_mode(data, MAX6650_CFG_MODE_CLOSED_LOOP);
687 #if IS_ENABLED(CONFIG_THERMAL)
689 static int max6650_get_max_state(struct thermal_cooling_device *cdev,
690 unsigned long *state)
697 static int max6650_get_cur_state(struct thermal_cooling_device *cdev,
698 unsigned long *state)
700 struct max6650_data *data = cdev->devdata;
702 *state = data->cooling_dev_state;
707 static int max6650_set_cur_state(struct thermal_cooling_device *cdev,
710 struct max6650_data *data = cdev->devdata;
711 struct i2c_client *client = data->client;
714 state = clamp_val(state, 0, 255);
716 mutex_lock(&data->update_lock);
718 if (data->config & MAX6650_CFG_V12)
719 data->dac = 180 - (180 * state)/255;
721 data->dac = 76 - (76 * state)/255;
723 err = i2c_smbus_write_byte_data(client, MAX6650_REG_DAC, data->dac);
726 max6650_set_operating_mode(data, state ?
727 MAX6650_CFG_MODE_OPEN_LOOP :
728 MAX6650_CFG_MODE_OFF);
729 data->cooling_dev_state = state;
732 mutex_unlock(&data->update_lock);
734 return err < 0 ? err : 0;
737 static const struct thermal_cooling_device_ops max6650_cooling_ops = {
738 .get_max_state = max6650_get_max_state,
739 .get_cur_state = max6650_get_cur_state,
740 .set_cur_state = max6650_set_cur_state,
744 static int max6650_probe(struct i2c_client *client,
745 const struct i2c_device_id *id)
747 struct device *dev = &client->dev;
748 const struct of_device_id *of_id =
749 of_match_device(of_match_ptr(max6650_dt_match), dev);
750 struct max6650_data *data;
751 struct device *hwmon_dev;
754 data = devm_kzalloc(dev, sizeof(struct max6650_data), GFP_KERNEL);
758 data->client = client;
759 i2c_set_clientdata(client, data);
760 mutex_init(&data->update_lock);
761 data->nr_fans = of_id ? (int)(uintptr_t)of_id->data : id->driver_data;
764 * Initialize the max6650 chip
766 err = max6650_init_client(data, client);
770 data->groups[0] = &max6650_group;
771 /* 3 additional fan inputs for the MAX6651 */
772 if (data->nr_fans == 4)
773 data->groups[1] = &max6651_group;
775 hwmon_dev = devm_hwmon_device_register_with_groups(dev,
778 err = PTR_ERR_OR_ZERO(hwmon_dev);
782 #if IS_ENABLED(CONFIG_THERMAL)
784 thermal_of_cooling_device_register(client->dev.of_node,
786 &max6650_cooling_ops);
787 if (IS_ERR(data->cooling_dev))
788 dev_warn(&client->dev,
789 "thermal cooling device register failed: %ld\n",
790 PTR_ERR(data->cooling_dev));
795 static int max6650_remove(struct i2c_client *client)
797 struct max6650_data *data = i2c_get_clientdata(client);
799 if (!IS_ERR(data->cooling_dev))
800 thermal_cooling_device_unregister(data->cooling_dev);
805 static const struct i2c_device_id max6650_id[] = {
810 MODULE_DEVICE_TABLE(i2c, max6650_id);
812 static struct i2c_driver max6650_driver = {
815 .of_match_table = of_match_ptr(max6650_dt_match),
817 .probe = max6650_probe,
818 .remove = max6650_remove,
819 .id_table = max6650_id,
822 module_i2c_driver(max6650_driver);
824 MODULE_AUTHOR("Hans J. Koch");
825 MODULE_DESCRIPTION("MAX6650 sensor driver");
826 MODULE_LICENSE("GPL");