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linux/drivers/hwmon/max31790.c
Guenter Roeck 1814c4e84d hwmon: (max31790) Detect and report zero fan speed 
If a fan is not running or not connected, of if fan monitoring is disabled,
the fan count register returns a fixed value of 0xffe0. So far this is then
translated to a RPM value larger than 0. Since this is misleading and does
not really make much sense, report a fan RPM of 0 in this situation.

Cc: Jan Kundrát <jan.kundrat@cesnet.cz>
Cc: Václav Kubernát <kubernat@cesnet.cz>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Tested-by: Václav Kubernát <kubernat@cesnet.cz>
Link: https://lore.kernel.org/r/20210526154022.3223012-7-linux@roeck-us.net
2021-06-17 04:21:46 -07:00

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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* max31790.c - Part of lm_sensors, Linux kernel modules for hardware
* monitoring.
*
* (C) 2015 by Il Han <corone.il.han@gmail.com>
*/
#include <linux/err.h>
#include <linux/hwmon.h>
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/jiffies.h>
#include <linux/module.h>
#include <linux/slab.h>
/* MAX31790 registers */
#define MAX31790_REG_GLOBAL_CONFIG 0x00
#define MAX31790_REG_FAN_CONFIG(ch) (0x02 + (ch))
#define MAX31790_REG_FAN_DYNAMICS(ch) (0x08 + (ch))
#define MAX31790_REG_FAN_FAULT_STATUS2 0x10
#define MAX31790_REG_FAN_FAULT_STATUS1 0x11
#define MAX31790_REG_TACH_COUNT(ch) (0x18 + (ch) * 2)
#define MAX31790_REG_PWM_DUTY_CYCLE(ch) (0x30 + (ch) * 2)
#define MAX31790_REG_PWMOUT(ch) (0x40 + (ch) * 2)
#define MAX31790_REG_TARGET_COUNT(ch) (0x50 + (ch) * 2)
/* Fan Config register bits */
#define MAX31790_FAN_CFG_RPM_MODE 0x80
#define MAX31790_FAN_CFG_CTRL_MON 0x10
#define MAX31790_FAN_CFG_TACH_INPUT_EN 0x08
#define MAX31790_FAN_CFG_TACH_INPUT 0x01
/* Fan Dynamics register bits */
#define MAX31790_FAN_DYN_SR_SHIFT 5
#define MAX31790_FAN_DYN_SR_MASK 0xE0
#define SR_FROM_REG(reg) (((reg) & MAX31790_FAN_DYN_SR_MASK) \
>> MAX31790_FAN_DYN_SR_SHIFT)
#define FAN_RPM_MIN 120
#define FAN_RPM_MAX 7864320
#define FAN_COUNT_REG_MAX 0xffe0
#define RPM_FROM_REG(reg, sr) (((reg) >> 4) ? \
((60 * (sr) * 8192) / ((reg) >> 4)) : \
FAN_RPM_MAX)
#define RPM_TO_REG(rpm, sr) ((60 * (sr) * 8192) / ((rpm) * 2))
#define NR_CHANNEL 6
/*
* Client data (each client gets its own)
*/
struct max31790_data {
struct i2c_client *client;
struct mutex update_lock;
bool valid; /* zero until following fields are valid */
unsigned long last_updated; /* in jiffies */
/* register values */
u8 fan_config[NR_CHANNEL];
u8 fan_dynamics[NR_CHANNEL];
u16 fault_status;
u16 tach[NR_CHANNEL * 2];
u16 pwm[NR_CHANNEL];
u16 target_count[NR_CHANNEL];
};
static struct max31790_data *max31790_update_device(struct device *dev)
{
struct max31790_data *data = dev_get_drvdata(dev);
struct i2c_client *client = data->client;
struct max31790_data *ret = data;
int i;
int rv;
mutex_lock(&data->update_lock);
if (time_after(jiffies, data->last_updated + HZ) || !data->valid) {
rv = i2c_smbus_read_byte_data(client,
MAX31790_REG_FAN_FAULT_STATUS1);
if (rv < 0)
goto abort;
data->fault_status |= rv & 0x3F;
rv = i2c_smbus_read_byte_data(client,
MAX31790_REG_FAN_FAULT_STATUS2);
if (rv < 0)
goto abort;
data->fault_status |= (rv & 0x3F) << 6;
for (i = 0; i < NR_CHANNEL; i++) {
rv = i2c_smbus_read_word_swapped(client,
MAX31790_REG_TACH_COUNT(i));
if (rv < 0)
goto abort;
data->tach[i] = rv;
if (data->fan_config[i]
& MAX31790_FAN_CFG_TACH_INPUT) {
rv = i2c_smbus_read_word_swapped(client,
MAX31790_REG_TACH_COUNT(NR_CHANNEL
+ i));
if (rv < 0)
goto abort;
data->tach[NR_CHANNEL + i] = rv;
} else {
rv = i2c_smbus_read_word_swapped(client,
MAX31790_REG_PWM_DUTY_CYCLE(i));
if (rv < 0)
goto abort;
data->pwm[i] = rv;
rv = i2c_smbus_read_word_swapped(client,
MAX31790_REG_TARGET_COUNT(i));
if (rv < 0)
goto abort;
data->target_count[i] = rv;
}
}
data->last_updated = jiffies;
data->valid = true;
}
goto done;
abort:
data->valid = false;
ret = ERR_PTR(rv);
done:
mutex_unlock(&data->update_lock);
return ret;
}
static const u8 tach_period[8] = { 1, 2, 4, 8, 16, 32, 32, 32 };
static u8 get_tach_period(u8 fan_dynamics)
{
return tach_period[SR_FROM_REG(fan_dynamics)];
}
static u8 bits_for_tach_period(int rpm)
{
u8 bits;
if (rpm < 500)
bits = 0x0;
else if (rpm < 1000)
bits = 0x1;
else if (rpm < 2000)
bits = 0x2;
else if (rpm < 4000)
bits = 0x3;
else if (rpm < 8000)
bits = 0x4;
else
bits = 0x5;
return bits;
}
static int max31790_read_fan(struct device *dev, u32 attr, int channel,
long *val)
{
struct max31790_data *data = max31790_update_device(dev);
int sr, rpm;
if (IS_ERR(data))
return PTR_ERR(data);
switch (attr) {
case hwmon_fan_input:
sr = get_tach_period(data->fan_dynamics[channel % NR_CHANNEL]);
if (data->tach[channel] == FAN_COUNT_REG_MAX)
rpm = 0;
else
rpm = RPM_FROM_REG(data->tach[channel], sr);
*val = rpm;
return 0;
case hwmon_fan_target:
sr = get_tach_period(data->fan_dynamics[channel]);
rpm = RPM_FROM_REG(data->target_count[channel], sr);
*val = rpm;
return 0;
case hwmon_fan_fault:
mutex_lock(&data->update_lock);
*val = !!(data->fault_status & (1 << channel));
data->fault_status &= ~(1 << channel);
/*
* If a fault bit is set, we need to write into one of the fan
* configuration registers to clear it. Note that this also
* clears the fault for the companion channel if enabled.
*/
if (*val) {
int reg = MAX31790_REG_TARGET_COUNT(channel % NR_CHANNEL);
i2c_smbus_write_byte_data(data->client, reg,
data->target_count[channel % NR_CHANNEL] >> 8);
}
mutex_unlock(&data->update_lock);
return 0;
default:
return -EOPNOTSUPP;
}
}
static int max31790_write_fan(struct device *dev, u32 attr, int channel,
long val)
{
struct max31790_data *data = dev_get_drvdata(dev);
struct i2c_client *client = data->client;
int target_count;
int err = 0;
u8 bits;
int sr;
mutex_lock(&data->update_lock);
switch (attr) {
case hwmon_fan_target:
val = clamp_val(val, FAN_RPM_MIN, FAN_RPM_MAX);
bits = bits_for_tach_period(val);
data->fan_dynamics[channel] =
((data->fan_dynamics[channel] &
~MAX31790_FAN_DYN_SR_MASK) |
(bits << MAX31790_FAN_DYN_SR_SHIFT));
err = i2c_smbus_write_byte_data(client,
MAX31790_REG_FAN_DYNAMICS(channel),
data->fan_dynamics[channel]);
if (err < 0)
break;
sr = get_tach_period(data->fan_dynamics[channel]);
target_count = RPM_TO_REG(val, sr);
target_count = clamp_val(target_count, 0x1, 0x7FF);
data->target_count[channel] = target_count << 5;
err = i2c_smbus_write_word_swapped(client,
MAX31790_REG_TARGET_COUNT(channel),
data->target_count[channel]);
break;
default:
err = -EOPNOTSUPP;
break;
}
mutex_unlock(&data->update_lock);
return err;
}
static umode_t max31790_fan_is_visible(const void *_data, u32 attr, int channel)
{
const struct max31790_data *data = _data;
u8 fan_config = data->fan_config[channel % NR_CHANNEL];
switch (attr) {
case hwmon_fan_input:
case hwmon_fan_fault:
if (channel < NR_CHANNEL ||
(fan_config & MAX31790_FAN_CFG_TACH_INPUT))
return 0444;
return 0;
case hwmon_fan_target:
if (channel < NR_CHANNEL &&
!(fan_config & MAX31790_FAN_CFG_TACH_INPUT))
return 0644;
return 0;
default:
return 0;
}
}
static int max31790_read_pwm(struct device *dev, u32 attr, int channel,
long *val)
{
struct max31790_data *data = max31790_update_device(dev);
u8 fan_config;
if (IS_ERR(data))
return PTR_ERR(data);
fan_config = data->fan_config[channel];
switch (attr) {
case hwmon_pwm_input:
*val = data->pwm[channel] >> 8;
return 0;
case hwmon_pwm_enable:
if (fan_config & MAX31790_FAN_CFG_CTRL_MON)
*val = 0;
else if (fan_config & MAX31790_FAN_CFG_RPM_MODE)
*val = 2;
else
*val = 1;
return 0;
default:
return -EOPNOTSUPP;
}
}
static int max31790_write_pwm(struct device *dev, u32 attr, int channel,
long val)
{
struct max31790_data *data = dev_get_drvdata(dev);
struct i2c_client *client = data->client;
u8 fan_config;
int err = 0;
mutex_lock(&data->update_lock);
switch (attr) {
case hwmon_pwm_input:
if (val < 0 || val > 255) {
err = -EINVAL;
break;
}
data->valid = false;
err = i2c_smbus_write_word_swapped(client,
MAX31790_REG_PWMOUT(channel),
val << 8);
break;
case hwmon_pwm_enable:
fan_config = data->fan_config[channel];
if (val == 0) {
fan_config |= MAX31790_FAN_CFG_CTRL_MON;
/*
* Disable RPM mode; otherwise disabling fan speed
* monitoring is not possible.
*/
fan_config &= ~MAX31790_FAN_CFG_RPM_MODE;
} else if (val == 1) {
fan_config &= ~(MAX31790_FAN_CFG_CTRL_MON | MAX31790_FAN_CFG_RPM_MODE);
} else if (val == 2) {
fan_config &= ~MAX31790_FAN_CFG_CTRL_MON;
/*
* The chip sets MAX31790_FAN_CFG_TACH_INPUT_EN on its
* own if MAX31790_FAN_CFG_RPM_MODE is set.
* Do it here as well to reflect the actual register
* value in the cache.
*/
fan_config |= (MAX31790_FAN_CFG_RPM_MODE | MAX31790_FAN_CFG_TACH_INPUT_EN);
} else {
err = -EINVAL;
break;
}
if (fan_config != data->fan_config[channel]) {
err = i2c_smbus_write_byte_data(client, MAX31790_REG_FAN_CONFIG(channel),
fan_config);
if (!err)
data->fan_config[channel] = fan_config;
}
break;
default:
err = -EOPNOTSUPP;
break;
}
mutex_unlock(&data->update_lock);
return err;
}
static umode_t max31790_pwm_is_visible(const void *_data, u32 attr, int channel)
{
const struct max31790_data *data = _data;
u8 fan_config = data->fan_config[channel];
switch (attr) {
case hwmon_pwm_input:
case hwmon_pwm_enable:
if (!(fan_config & MAX31790_FAN_CFG_TACH_INPUT))
return 0644;
return 0;
default:
return 0;
}
}
static int max31790_read(struct device *dev, enum hwmon_sensor_types type,
u32 attr, int channel, long *val)
{
switch (type) {
case hwmon_fan:
return max31790_read_fan(dev, attr, channel, val);
case hwmon_pwm:
return max31790_read_pwm(dev, attr, channel, val);
default:
return -EOPNOTSUPP;
}
}
static int max31790_write(struct device *dev, enum hwmon_sensor_types type,
u32 attr, int channel, long val)
{
switch (type) {
case hwmon_fan:
return max31790_write_fan(dev, attr, channel, val);
case hwmon_pwm:
return max31790_write_pwm(dev, attr, channel, val);
default:
return -EOPNOTSUPP;
}
}
static umode_t max31790_is_visible(const void *data,
enum hwmon_sensor_types type,
u32 attr, int channel)
{
switch (type) {
case hwmon_fan:
return max31790_fan_is_visible(data, attr, channel);
case hwmon_pwm:
return max31790_pwm_is_visible(data, attr, channel);
default:
return 0;
}
}
static const struct hwmon_channel_info *max31790_info[] = {
HWMON_CHANNEL_INFO(fan,
HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT,
HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT,
HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT,
HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT,
HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT,
HWMON_F_INPUT | HWMON_F_TARGET | HWMON_F_FAULT,
HWMON_F_INPUT | HWMON_F_FAULT,
HWMON_F_INPUT | HWMON_F_FAULT,
HWMON_F_INPUT | HWMON_F_FAULT,
HWMON_F_INPUT | HWMON_F_FAULT,
HWMON_F_INPUT | HWMON_F_FAULT,
HWMON_F_INPUT | HWMON_F_FAULT),
HWMON_CHANNEL_INFO(pwm,
HWMON_PWM_INPUT | HWMON_PWM_ENABLE,
HWMON_PWM_INPUT | HWMON_PWM_ENABLE,
HWMON_PWM_INPUT | HWMON_PWM_ENABLE,
HWMON_PWM_INPUT | HWMON_PWM_ENABLE,
HWMON_PWM_INPUT | HWMON_PWM_ENABLE,
HWMON_PWM_INPUT | HWMON_PWM_ENABLE),
NULL
};
static const struct hwmon_ops max31790_hwmon_ops = {
.is_visible = max31790_is_visible,
.read = max31790_read,
.write = max31790_write,
};
static const struct hwmon_chip_info max31790_chip_info = {
.ops = &max31790_hwmon_ops,
.info = max31790_info,
};
static int max31790_init_client(struct i2c_client *client,
struct max31790_data *data)
{
int i, rv;
for (i = 0; i < NR_CHANNEL; i++) {
rv = i2c_smbus_read_byte_data(client,
MAX31790_REG_FAN_CONFIG(i));
if (rv < 0)
return rv;
data->fan_config[i] = rv;
rv = i2c_smbus_read_byte_data(client,
MAX31790_REG_FAN_DYNAMICS(i));
if (rv < 0)
return rv;
data->fan_dynamics[i] = rv;
}
return 0;
}
static int max31790_probe(struct i2c_client *client)
{
struct i2c_adapter *adapter = client->adapter;
struct device *dev = &client->dev;
struct max31790_data *data;
struct device *hwmon_dev;
int err;
if (!i2c_check_functionality(adapter,
I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA))
return -ENODEV;
data = devm_kzalloc(dev, sizeof(struct max31790_data), GFP_KERNEL);
if (!data)
return -ENOMEM;
data->client = client;
mutex_init(&data->update_lock);
/*
* Initialize the max31790 chip
*/
err = max31790_init_client(client, data);
if (err)
return err;
hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name,
data,
&max31790_chip_info,
NULL);
return PTR_ERR_OR_ZERO(hwmon_dev);
}
static const struct i2c_device_id max31790_id[] = {
{ "max31790", 0 },
{ }
};
MODULE_DEVICE_TABLE(i2c, max31790_id);
static struct i2c_driver max31790_driver = {
.class = I2C_CLASS_HWMON,
.probe_new = max31790_probe,
.driver = {
.name = "max31790",
},
.id_table = max31790_id,
};
module_i2c_driver(max31790_driver);
MODULE_AUTHOR("Il Han <corone.il.han@gmail.com>");
MODULE_DESCRIPTION("MAX31790 sensor driver");
MODULE_LICENSE("GPL");
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