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))
96 #define DAC_LIMIT(v12) ((v12) ? 180 : 76)
99 * Client data (each client gets its own)
102 struct max6650_data {
103 struct i2c_client *client;
104 struct mutex update_lock;
106 bool valid; /* false until following fields are valid */
107 unsigned long last_updated; /* in jiffies */
109 /* 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 int dac_to_pwm(int dac, bool v12)
143 * Useful range for dac is 0-180 for 12V fans and 0-76 for 5V fans.
144 * Lower DAC values mean higher speeds.
146 return clamp_val(255 - (255 * dac) / DAC_LIMIT(v12), 0, 255);
149 static u8 pwm_to_dac(unsigned int pwm, bool v12)
151 int limit = DAC_LIMIT(v12);
153 return limit - (limit * pwm) / 255;
156 static struct max6650_data *max6650_update_device(struct device *dev)
158 struct max6650_data *data = dev_get_drvdata(dev);
159 struct i2c_client *client = data->client;
162 mutex_lock(&data->update_lock);
164 if (time_after(jiffies, data->last_updated + HZ) || !data->valid) {
165 data->speed = i2c_smbus_read_byte_data(client,
167 data->config = i2c_smbus_read_byte_data(client,
169 for (i = 0; i < data->nr_fans; i++) {
170 data->tach[i] = i2c_smbus_read_byte_data(client,
173 data->count = i2c_smbus_read_byte_data(client,
175 data->dac = i2c_smbus_read_byte_data(client, MAX6650_REG_DAC);
178 * Alarms are cleared on read in case the condition that
179 * caused the alarm is removed. Keep the value latched here
180 * for providing the register through different alarm files.
182 data->alarm |= i2c_smbus_read_byte_data(client,
185 data->last_updated = jiffies;
189 mutex_unlock(&data->update_lock);
195 * Change the operating mode of the chip (if needed).
196 * mode is one of the MAX6650_CFG_MODE_* values.
198 static int max6650_set_operating_mode(struct max6650_data *data, u8 mode)
201 u8 config = data->config;
203 if (mode == (config & MAX6650_CFG_MODE_MASK))
206 config = (config & ~MAX6650_CFG_MODE_MASK) | mode;
208 result = i2c_smbus_write_byte_data(data->client, MAX6650_REG_CONFIG,
213 data->config = config;
219 * Set the fan speed to the specified RPM (or read back the RPM setting).
220 * This works in closed loop mode only. Use pwm1 for open loop speed setting.
222 * The MAX6650/1 will automatically control fan speed when in closed loop
227 * 1) The MAX6650/1 internal 254kHz clock frequency is set correctly. Use
228 * the clock module parameter if you need to fine tune this.
230 * 2) The prescaler (low three bits of the config register) has already
231 * been set to an appropriate value. Use the prescaler module parameter
232 * if your BIOS doesn't initialize the chip properly.
234 * The relevant equations are given on pages 21 and 22 of the datasheet.
236 * From the datasheet, the relevant equation when in regulation is:
238 * [fCLK / (128 x (KTACH + 1))] = 2 x FanSpeed / KSCALE
242 * fCLK is the oscillator frequency (either the 254kHz internal
243 * oscillator or the externally applied clock)
245 * KTACH is the value in the speed register
247 * FanSpeed is the speed of the fan in rps
249 * KSCALE is the prescaler value (1, 2, 4, 8, or 16)
251 * When reading, we need to solve for FanSpeed. When writing, we need to
254 * Note: this tachometer is completely separate from the tachometers
255 * used to measure the fan speeds. Only one fan's speed (fan1) is
259 static int max6650_set_target(struct max6650_data *data, unsigned long rpm)
264 return max6650_set_operating_mode(data, MAX6650_CFG_MODE_OFF);
266 rpm = clamp_val(rpm, FAN_RPM_MIN, FAN_RPM_MAX);
269 * Divide the required speed by 60 to get from rpm to rps, then
270 * use the datasheet equation:
272 * KTACH = [(fCLK x KSCALE) / (256 x FanSpeed)] - 1
275 kscale = DIV_FROM_REG(data->config);
276 ktach = ((clock * kscale) / (256 * rpm / 60)) - 1;
283 return i2c_smbus_write_byte_data(data->client, MAX6650_REG_SPEED,
288 * Get gpio alarm status:
294 static ssize_t alarm_show(struct device *dev,
295 struct device_attribute *devattr, char *buf)
297 struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
298 struct max6650_data *data = max6650_update_device(dev);
299 bool alarm = data->alarm & attr->index;
302 mutex_lock(&data->update_lock);
303 data->alarm &= ~attr->index;
305 mutex_unlock(&data->update_lock);
308 return sprintf(buf, "%d\n", alarm);
311 static SENSOR_DEVICE_ATTR_RO(gpio1_alarm, alarm, MAX6650_ALRM_GPIO1);
312 static SENSOR_DEVICE_ATTR_RO(gpio2_alarm, alarm, MAX6650_ALRM_GPIO2);
314 static umode_t max6650_attrs_visible(struct kobject *kobj, struct attribute *a,
317 struct device *dev = container_of(kobj, struct device, kobj);
318 struct max6650_data *data = dev_get_drvdata(dev);
319 struct device_attribute *devattr;
322 * Hide the alarms that have not been enabled by the firmware
325 devattr = container_of(a, struct device_attribute, attr);
326 if (devattr == &sensor_dev_attr_gpio1_alarm.dev_attr ||
327 devattr == &sensor_dev_attr_gpio2_alarm.dev_attr) {
328 if (!(data->alarm_en & to_sensor_dev_attr(devattr)->index))
335 static struct attribute *max6650_attrs[] = {
336 &sensor_dev_attr_gpio1_alarm.dev_attr.attr,
337 &sensor_dev_attr_gpio2_alarm.dev_attr.attr,
341 static const struct attribute_group max6650_group = {
342 .attrs = max6650_attrs,
343 .is_visible = max6650_attrs_visible,
346 static const struct attribute_group *max6650_groups[] = {
351 static int max6650_init_client(struct max6650_data *data,
352 struct i2c_client *client)
354 struct device *dev = &client->dev;
361 if (of_property_read_u32(dev->of_node, "maxim,fan-microvolt",
363 voltage = fan_voltage;
365 voltage /= 1000000; /* Microvolts to volts */
366 if (of_property_read_u32(dev->of_node, "maxim,fan-prescale",
368 prescale = prescaler;
370 reg = i2c_smbus_read_byte_data(client, MAX6650_REG_CONFIG);
372 dev_err(dev, "Error reading config register, aborting.\n");
380 reg &= ~MAX6650_CFG_V12;
383 reg |= MAX6650_CFG_V12;
386 dev_err(dev, "illegal value for fan_voltage (%d)\n", voltage);
393 reg &= ~MAX6650_CFG_PRESCALER_MASK;
396 reg = (reg & ~MAX6650_CFG_PRESCALER_MASK)
397 | MAX6650_CFG_PRESCALER_2;
400 reg = (reg & ~MAX6650_CFG_PRESCALER_MASK)
401 | MAX6650_CFG_PRESCALER_4;
404 reg = (reg & ~MAX6650_CFG_PRESCALER_MASK)
405 | MAX6650_CFG_PRESCALER_8;
408 reg = (reg & ~MAX6650_CFG_PRESCALER_MASK)
409 | MAX6650_CFG_PRESCALER_16;
412 dev_err(dev, "illegal value for prescaler (%d)\n", prescale);
415 dev_info(dev, "Fan voltage: %dV, prescaler: %d.\n",
416 (reg & MAX6650_CFG_V12) ? 12 : 5,
417 1 << (reg & MAX6650_CFG_PRESCALER_MASK));
419 err = i2c_smbus_write_byte_data(client, MAX6650_REG_CONFIG, reg);
421 dev_err(dev, "Config write error, aborting.\n");
426 reg = i2c_smbus_read_byte_data(client, MAX6650_REG_COUNT);
428 dev_err(dev, "Failed to read count register, aborting.\n");
433 reg = i2c_smbus_read_byte_data(client, MAX6650_REG_ALARM_EN);
435 dev_err(dev, "Failed to read alarm configuration, aborting.\n");
438 data->alarm_en = reg;
440 if (!of_property_read_u32(client->dev.of_node, "maxim,fan-target-rpm",
442 max6650_set_target(data, target_rpm);
443 max6650_set_operating_mode(data, MAX6650_CFG_MODE_CLOSED_LOOP);
449 #if IS_ENABLED(CONFIG_THERMAL)
451 static int max6650_get_max_state(struct thermal_cooling_device *cdev,
452 unsigned long *state)
459 static int max6650_get_cur_state(struct thermal_cooling_device *cdev,
460 unsigned long *state)
462 struct max6650_data *data = cdev->devdata;
464 *state = data->cooling_dev_state;
469 static int max6650_set_cur_state(struct thermal_cooling_device *cdev,
472 struct max6650_data *data = cdev->devdata;
473 struct i2c_client *client = data->client;
476 state = clamp_val(state, 0, 255);
478 mutex_lock(&data->update_lock);
480 data->dac = pwm_to_dac(state, data->config & MAX6650_CFG_V12);
481 err = i2c_smbus_write_byte_data(client, MAX6650_REG_DAC, data->dac);
484 max6650_set_operating_mode(data, state ?
485 MAX6650_CFG_MODE_OPEN_LOOP :
486 MAX6650_CFG_MODE_OFF);
487 data->cooling_dev_state = state;
490 mutex_unlock(&data->update_lock);
495 static const struct thermal_cooling_device_ops max6650_cooling_ops = {
496 .get_max_state = max6650_get_max_state,
497 .get_cur_state = max6650_get_cur_state,
498 .set_cur_state = max6650_set_cur_state,
502 static int max6650_read(struct device *dev, enum hwmon_sensor_types type,
503 u32 attr, int channel, long *val)
505 struct max6650_data *data = max6650_update_device(dev);
511 case hwmon_pwm_input:
512 *val = dac_to_pwm(data->dac,
513 data->config & MAX6650_CFG_V12);
515 case hwmon_pwm_enable:
519 * 1 = Open loop, Voltage is set according to speed,
521 * 2 = Closed loop, RPM for all fans regulated by fan1
525 mode = (data->config & MAX6650_CFG_MODE_MASK) >> 4;
526 *val = (4 - mode) & 3; /* {0 1 2 3} -> {0 3 2 1} */
534 case hwmon_fan_input:
536 * Calculation details:
538 * Each tachometer counts over an interval given by the
539 * "count" register (0.25, 0.5, 1 or 2 seconds).
540 * The driver assumes that the fans produce two pulses
541 * per revolution (this seems to be the most common).
543 *val = DIV_ROUND_CLOSEST(data->tach[channel] * 120,
544 DIV_FROM_REG(data->count));
547 *val = DIV_FROM_REG(data->count);
549 case hwmon_fan_target:
551 * Use the datasheet equation:
552 * FanSpeed = KSCALE x fCLK / [256 x (KTACH + 1)]
553 * then multiply by 60 to give rpm.
555 *val = 60 * DIV_FROM_REG(data->config) * clock /
556 (256 * (data->speed + 1));
558 case hwmon_fan_min_alarm:
559 *val = !!(data->alarm & MAX6650_ALRM_MIN);
560 data->alarm &= ~MAX6650_ALRM_MIN;
563 case hwmon_fan_max_alarm:
564 *val = !!(data->alarm & MAX6650_ALRM_MAX);
565 data->alarm &= ~MAX6650_ALRM_MAX;
568 case hwmon_fan_fault:
569 *val = !!(data->alarm & MAX6650_ALRM_TACH);
570 data->alarm &= ~MAX6650_ALRM_TACH;
583 static const u8 max6650_pwm_modes[] = {
585 MAX6650_CFG_MODE_OPEN_LOOP,
586 MAX6650_CFG_MODE_CLOSED_LOOP,
587 MAX6650_CFG_MODE_OFF,
590 static int max6650_write(struct device *dev, enum hwmon_sensor_types type,
591 u32 attr, int channel, long val)
593 struct max6650_data *data = dev_get_drvdata(dev);
597 mutex_lock(&data->update_lock);
602 case hwmon_pwm_input:
603 reg = pwm_to_dac(clamp_val(val, 0, 255),
604 data->config & MAX6650_CFG_V12);
605 ret = i2c_smbus_write_byte_data(data->client,
606 MAX6650_REG_DAC, reg);
611 case hwmon_pwm_enable:
612 if (val < 0 || val >= ARRAY_SIZE(max6650_pwm_modes)) {
616 ret = max6650_set_operating_mode(data,
617 max6650_pwm_modes[val]);
644 ret = i2c_smbus_write_byte_data(data->client,
645 MAX6650_REG_COUNT, reg);
650 case hwmon_fan_target:
655 ret = max6650_set_target(data, val);
668 mutex_unlock(&data->update_lock);
672 static umode_t max6650_is_visible(const void *_data,
673 enum hwmon_sensor_types type, u32 attr,
676 const struct max6650_data *data = _data;
678 if (channel && (channel >= data->nr_fans || type != hwmon_fan))
684 case hwmon_fan_input:
686 case hwmon_fan_target:
689 case hwmon_fan_min_alarm:
690 if (data->alarm_en & MAX6650_ALRM_MIN)
693 case hwmon_fan_max_alarm:
694 if (data->alarm_en & MAX6650_ALRM_MAX)
697 case hwmon_fan_fault:
698 if (data->alarm_en & MAX6650_ALRM_TACH)
707 case hwmon_pwm_input:
708 case hwmon_pwm_enable:
720 static const struct hwmon_channel_info *max6650_info[] = {
721 HWMON_CHANNEL_INFO(fan, HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_DIV |
722 HWMON_F_MIN_ALARM | HWMON_F_MAX_ALARM |
724 HWMON_F_INPUT, HWMON_F_INPUT, HWMON_F_INPUT),
725 HWMON_CHANNEL_INFO(pwm, HWMON_PWM_INPUT | HWMON_PWM_ENABLE),
729 static const struct hwmon_ops max6650_hwmon_ops = {
730 .read = max6650_read,
731 .write = max6650_write,
732 .is_visible = max6650_is_visible,
735 static const struct hwmon_chip_info max6650_chip_info = {
736 .ops = &max6650_hwmon_ops,
737 .info = max6650_info,
740 static int max6650_probe(struct i2c_client *client,
741 const struct i2c_device_id *id)
743 struct thermal_cooling_device *cooling_dev;
744 struct device *dev = &client->dev;
745 const struct of_device_id *of_id =
746 of_match_device(of_match_ptr(max6650_dt_match), dev);
747 struct max6650_data *data;
748 struct device *hwmon_dev;
751 data = devm_kzalloc(dev, sizeof(struct max6650_data), GFP_KERNEL);
755 data->client = client;
756 i2c_set_clientdata(client, data);
757 mutex_init(&data->update_lock);
758 data->nr_fans = of_id ? (int)(uintptr_t)of_id->data : id->driver_data;
761 * Initialize the max6650 chip
763 err = max6650_init_client(data, client);
767 hwmon_dev = devm_hwmon_device_register_with_info(dev,
771 err = PTR_ERR_OR_ZERO(hwmon_dev);
775 #if IS_ENABLED(CONFIG_THERMAL)
776 cooling_dev = devm_thermal_of_cooling_device_register(dev, dev->of_node,
777 client->name, data, &max6650_cooling_ops);
778 if (IS_ERR(cooling_dev)) {
779 dev_warn(dev, "thermal cooling device register failed: %ld\n",
780 PTR_ERR(cooling_dev));
786 static const struct i2c_device_id max6650_id[] = {
791 MODULE_DEVICE_TABLE(i2c, max6650_id);
793 static struct i2c_driver max6650_driver = {
796 .of_match_table = of_match_ptr(max6650_dt_match),
798 .probe = max6650_probe,
799 .id_table = max6650_id,
802 module_i2c_driver(max6650_driver);
804 MODULE_AUTHOR("Hans J. Koch");
805 MODULE_DESCRIPTION("MAX6650 sensor driver");
806 MODULE_LICENSE("GPL");