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hwmon: Add MAX31827 driver

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MAX31827 is a low-power temperature switch with I2C interface.

The device is a ±1°C accuracy from -40°C to +125°C
(12 bits) local temperature switch and sensor with I2C/SM-
Bus interface. The combination of small 6-bump wafer-lev-
el package (WLP) and high accuracy makes this temper-
ature sensor/switch ideal for a wide range of applications.

Signed-off-by: Daniel Matyas <daniel.matyas@analog.com>
Link: https://lore.kernel.org/r/20230524160131.14081-2-daniel.matyas@analog.com
[groeck: Improved define alignment, return -EINVAL after bad user input,
 fixed up compatible statement]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
This commit is contained in:
Daniel Matyas 2023-05-24 19:01:30 +03:00 committed by Guenter Roeck
parent 9702fc8768
commit 16d60ba8fd
6 changed files with 571 additions and 1 deletions
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1
Documentation/hwmon/index.rst
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@ -140,6 +140,7 @@ Hardware Monitoring Kernel Drivers
max31760
max31785
max31790
max31827
max34440
max6620
max6639

90
Documentation/hwmon/max31827.rst Normal file
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@ -0,0 +1,90 @@
.. SPDX-License-Identifier: GPL-2.0
Kernel driver max31827
======================
Supported chips:
* Maxim MAX31827
Prefix: 'max31827'
Addresses scanned: I2C 0x40 - 0x5f
Datasheet: Publicly available at the Analog Devices website
* Maxim MAX31828
Prefix: 'max31828'
Addresses scanned: I2C 0x40 - 0x5f
Datasheet: Publicly available at the Analog Devices website
* Maxim MAX31829
Prefix: 'max31829'
Addresses scanned: I2C 0x40 - 0x5f
Datasheet: Publicly available at the Analog Devices website
Authors:
- Daniel Matyas <daniel.matyas@analog.com>
Description
-----------
The chips supported by this driver are quite similar. The only difference
between them is found in the default power-on behaviour of the chips. While the
MAX31827's fault queue is set to 1, the other two chip's fault queue is set to
4. Besides this, the MAX31829's alarm active state is high, while the other two
chip's alarms are active on low. It is important to note that the chips can be
configured to operate in the same manner with 1 write operation to the
configuration register. From here on, we will refer to all these chips as
MAX31827.
MAX31827 implements a temperature sensor with a 6 WLP packaging scheme. This
sensor measures the temperature of the chip itself.
MAX31827 has low and over temperature alarms with an effective value and a
hysteresis value: -40 and -30 degrees for under temperature alarm and +100 and
+90 degrees for over temperature alarm.
The alarm can be configured in comparator and interrupt mode. Currently only
comparator mode is implemented. In Comparator mode, the OT/UT status bits have a
value of 1 when the temperature rises above the TH value or falls below TL,
which is also subject to the Fault Queue selection. OT status returns to 0 when
the temperature drops below the TH_HYST value or when shutdown mode is entered.
Similarly, UT status returns to 0 when the temperature rises above TL_HYST value
or when shutdown mode is entered.
Putting the MAX31827 into shutdown mode also resets the OT/UT status bits. Note
that if the mode is changed while OT/UT status bits are set, an OT/UT status
reset may be required before it begins to behave normally. To prevent this,
it is recommended to perform a read of the configuration/status register to
clear the status bits before changing the operating mode.
The conversions can be manual with the one-shot functionality and automatic with
a set frequency. When powered on, the chip measures temperatures with 1 conv/s.
Enabling the device when it is already enabled has the side effect of setting
the conversion frequency to 1 conv/s. The conversion time varies depending on
the resolution. The conversion time doubles with every bit of increased
resolution. For 10 bit resolution 35ms are needed, while for 12 bit resolution
(default) 140ms. When chip is in shutdown mode and a read operation is
requested, one-shot is triggered, the device waits for 140 (conversion time) + 1
(error) ms, and only after that is the temperature value register read.
The LSB of the temperature values is 0.0625 degrees Celsius, but the values of
the temperatures are displayed in milli-degrees. This means, that some data is
lost. The step between 2 consecutive values is 62 or 63. This effect can be seen
in the writing of alarm values too. For positive numbers the user-input value
will always be rounded down to the nearest possible value, for negative numbers
the user-input will always be rounded up to the nearest possible value.
Notes
-----
Currently fault queue, alarm polarity and resolution cannot be modified.
PEC is not implemented either.

2
MAINTAINERS
View File

@ -12623,6 +12623,8 @@ L: linux-hwmon@vger.kernel.org
S: Supported
W: http://ez.analog.com/community/linux-device-drivers
F: Documentation/devicetree/bindings/hwmon/adi,max31827.yaml
F: Documentation/hwmon/max31827.rst
F: drivers/hwmon/max31827.c
MAX6650 HARDWARE MONITOR AND FAN CONTROLLER DRIVER
L: linux-hwmon@vger.kernel.org

11
drivers/hwmon/Kconfig
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@ -1098,6 +1098,17 @@ config SENSORS_MAX31760
This driver can also be built as a module. If so, the module
will be called max31760.
config MAX31827
tristate "MAX31827 low-power temperature switch and similar devices"
depends on I2C
select REGMAP_I2C
help
If you say yes here you get support for MAX31827, MAX31828 and
MAX31829 low-power temperature switches and sensors connected with I2C.
This driver can also be built as a module. If so, the module
will be called max31827.
config SENSORS_MAX6620
tristate "Maxim MAX6620 fan controller"
depends on I2C

2
drivers/hwmon/Makefile
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@ -149,6 +149,7 @@ obj-$(CONFIG_SENSORS_MAX6642) += max6642.o
obj-$(CONFIG_SENSORS_MAX6650) += max6650.o
obj-$(CONFIG_SENSORS_MAX6697) += max6697.o
obj-$(CONFIG_SENSORS_MAX31790) += max31790.o
obj-$(CONFIG_MAX31827) += max31827.o
obj-$(CONFIG_SENSORS_MC13783_ADC)+= mc13783-adc.o
obj-$(CONFIG_SENSORS_MC34VR500) += mc34vr500.o
obj-$(CONFIG_SENSORS_MCP3021) += mcp3021.o
@ -224,4 +225,3 @@ obj-$(CONFIG_SENSORS_PECI) += peci/
obj-$(CONFIG_PMBUS) += pmbus/
ccflags-$(CONFIG_HWMON_DEBUG_CHIP) := -DDEBUG

466
drivers/hwmon/max31827.c Normal file
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@ -0,0 +1,466 @@
// SPDX-License-Identifier: GPL-2.0
/*
* max31827.c - Support for Maxim Low-Power Switch
*
* Copyright (c) 2023 Daniel Matyas <daniel.matyas@analog.com>
*/
#include <linux/bitfield.h>
#include <linux/bitops.h>
#include <linux/delay.h>
#include <linux/hwmon.h>
#include <linux/i2c.h>
#include <linux/mutex.h>
#include <linux/regmap.h>
#define MAX31827_T_REG 0x0
#define MAX31827_CONFIGURATION_REG 0x2
#define MAX31827_TH_REG 0x4
#define MAX31827_TL_REG 0x6
#define MAX31827_TH_HYST_REG 0x8
#define MAX31827_TL_HYST_REG 0xA
#define MAX31827_CONFIGURATION_1SHOT_MASK BIT(0)
#define MAX31827_CONFIGURATION_CNV_RATE_MASK GENMASK(3, 1)
#define MAX31827_CONFIGURATION_U_TEMP_STAT_MASK BIT(14)
#define MAX31827_CONFIGURATION_O_TEMP_STAT_MASK BIT(15)
#define MAX31827_12_BIT_CNV_TIME 141
#define MAX31827_CNV_1_DIV_64_HZ 0x1
#define MAX31827_CNV_1_DIV_32_HZ 0x2
#define MAX31827_CNV_1_DIV_16_HZ 0x3
#define MAX31827_CNV_1_DIV_4_HZ 0x4
#define MAX31827_CNV_1_HZ 0x5
#define MAX31827_CNV_4_HZ 0x6
#define MAX31827_CNV_8_HZ 0x7
#define MAX31827_16_BIT_TO_M_DGR(x) (sign_extend32(x, 15) * 1000 / 16)
#define MAX31827_M_DGR_TO_16_BIT(x) (((x) << 4) / 1000)
#define MAX31827_DEVICE_ENABLE(x) ((x) ? 0xA : 0x0)
struct max31827_state {
/*
* Prevent simultaneous access to the i2c client.
*/
struct mutex lock;
struct regmap *regmap;
bool enable;
};
static const struct regmap_config max31827_regmap = {
.reg_bits = 8,
.val_bits = 16,
.max_register = 0xA,
};
static int write_alarm_val(struct max31827_state *st, unsigned int reg,
long val)
{
unsigned int cfg;
unsigned int tmp;
int ret;
val = MAX31827_M_DGR_TO_16_BIT(val);
/*
* Before the Temperature Threshold Alarm and Alarm Hysteresis Threshold
* register values are changed over I2C, the part must be in shutdown
* mode.
*
* Mutex is used to ensure, that some other process doesn't change the
* configuration register.
*/
mutex_lock(&st->lock);
if (!st->enable) {
ret = regmap_write(st->regmap, reg, val);
goto unlock;
}
ret = regmap_read(st->regmap, MAX31827_CONFIGURATION_REG, &cfg);
if (ret)
goto unlock;
tmp = cfg & ~(MAX31827_CONFIGURATION_1SHOT_MASK |
MAX31827_CONFIGURATION_CNV_RATE_MASK);
ret = regmap_write(st->regmap, MAX31827_CONFIGURATION_REG, tmp);
if (ret)
goto unlock;
ret = regmap_write(st->regmap, reg, val);
if (ret)
goto unlock;
ret = regmap_write(st->regmap, MAX31827_CONFIGURATION_REG, cfg);
unlock:
mutex_unlock(&st->lock);
return ret;
}
static umode_t max31827_is_visible(const void *state,
enum hwmon_sensor_types type, u32 attr,
int channel)
{
if (type == hwmon_temp) {
switch (attr) {
case hwmon_temp_enable:
case hwmon_temp_max:
case hwmon_temp_min:
case hwmon_temp_max_hyst:
case hwmon_temp_min_hyst:
return 0644;
case hwmon_temp_input:
case hwmon_temp_min_alarm:
case hwmon_temp_max_alarm:
return 0444;
default:
return 0;
}
} else if (type == hwmon_chip) {
if (attr == hwmon_chip_update_interval)
return 0644;
}
return 0;
}
static int max31827_read(struct device *dev, enum hwmon_sensor_types type,
u32 attr, int channel, long *val)
{
struct max31827_state *st = dev_get_drvdata(dev);
unsigned int uval;
int ret = 0;
switch (type) {
case hwmon_temp:
switch (attr) {
case hwmon_temp_enable:
ret = regmap_read(st->regmap,
MAX31827_CONFIGURATION_REG, &uval);
if (ret)
break;
uval = FIELD_GET(MAX31827_CONFIGURATION_1SHOT_MASK |
MAX31827_CONFIGURATION_CNV_RATE_MASK,
uval);
*val = !!uval;
break;
case hwmon_temp_input:
mutex_lock(&st->lock);
if (!st->enable) {
/*
* This operation requires mutex protection,
* because the chip configuration should not
* be changed during the conversion process.
*/
ret = regmap_update_bits(st->regmap,
MAX31827_CONFIGURATION_REG,
MAX31827_CONFIGURATION_1SHOT_MASK,
1);
if (ret) {
mutex_unlock(&st->lock);
return ret;
}
msleep(MAX31827_12_BIT_CNV_TIME);
}
ret = regmap_read(st->regmap, MAX31827_T_REG, &uval);
mutex_unlock(&st->lock);
if (ret)
break;
*val = MAX31827_16_BIT_TO_M_DGR(uval);
break;
case hwmon_temp_max:
ret = regmap_read(st->regmap, MAX31827_TH_REG, &uval);
if (ret)
break;
*val = MAX31827_16_BIT_TO_M_DGR(uval);
break;
case hwmon_temp_max_hyst:
ret = regmap_read(st->regmap, MAX31827_TH_HYST_REG,
&uval);
if (ret)
break;
*val = MAX31827_16_BIT_TO_M_DGR(uval);
break;
case hwmon_temp_max_alarm:
ret = regmap_read(st->regmap,
MAX31827_CONFIGURATION_REG, &uval);
if (ret)
break;
*val = FIELD_GET(MAX31827_CONFIGURATION_O_TEMP_STAT_MASK,
uval);
break;
case hwmon_temp_min:
ret = regmap_read(st->regmap, MAX31827_TL_REG, &uval);
if (ret)
break;
*val = MAX31827_16_BIT_TO_M_DGR(uval);
break;
case hwmon_temp_min_hyst:
ret = regmap_read(st->regmap, MAX31827_TL_HYST_REG,
&uval);
if (ret)
break;
*val = MAX31827_16_BIT_TO_M_DGR(uval);
break;
case hwmon_temp_min_alarm:
ret = regmap_read(st->regmap,
MAX31827_CONFIGURATION_REG, &uval);
if (ret)
break;
*val = FIELD_GET(MAX31827_CONFIGURATION_U_TEMP_STAT_MASK,
uval);
break;
default:
ret = -EOPNOTSUPP;
break;
}
break;
case hwmon_chip:
if (attr == hwmon_chip_update_interval) {
ret = regmap_read(st->regmap,
MAX31827_CONFIGURATION_REG, &uval);
if (ret)
break;
uval = FIELD_GET(MAX31827_CONFIGURATION_CNV_RATE_MASK,
uval);
switch (uval) {
case MAX31827_CNV_1_DIV_64_HZ:
*val = 64000;
break;
case MAX31827_CNV_1_DIV_32_HZ:
*val = 32000;
break;
case MAX31827_CNV_1_DIV_16_HZ:
*val = 16000;
break;
case MAX31827_CNV_1_DIV_4_HZ:
*val = 4000;
break;
case MAX31827_CNV_1_HZ:
*val = 1000;
break;
case MAX31827_CNV_4_HZ:
*val = 250;
break;
case MAX31827_CNV_8_HZ:
*val = 125;
break;
default:
*val = 0;
break;
}
}
break;
default:
ret = -EOPNOTSUPP;
break;
}
return ret;
}
static int max31827_write(struct device *dev, enum hwmon_sensor_types type,
u32 attr, int channel, long val)
{
struct max31827_state *st = dev_get_drvdata(dev);
int ret;
switch (type) {
case hwmon_temp:
switch (attr) {
case hwmon_temp_enable:
if (val >> 1)
return -EINVAL;
mutex_lock(&st->lock);
/**
* The chip should not be enabled while a conversion is
* performed. Neither should the chip be enabled when
* the alarm values are changed.
*/
st->enable = val;
ret = regmap_update_bits(st->regmap,
MAX31827_CONFIGURATION_REG,
MAX31827_CONFIGURATION_1SHOT_MASK |
MAX31827_CONFIGURATION_CNV_RATE_MASK,
MAX31827_DEVICE_ENABLE(val));
mutex_unlock(&st->lock);
return ret;
case hwmon_temp_max:
return write_alarm_val(st, MAX31827_TH_REG, val);
case hwmon_temp_max_hyst:
return write_alarm_val(st, MAX31827_TH_HYST_REG, val);
case hwmon_temp_min:
return write_alarm_val(st, MAX31827_TL_REG, val);
case hwmon_temp_min_hyst:
return write_alarm_val(st, MAX31827_TL_HYST_REG, val);
default:
return -EOPNOTSUPP;
}
case hwmon_chip:
if (attr == hwmon_chip_update_interval) {
if (!st->enable)
return -EINVAL;
switch (val) {
case 125:
val = MAX31827_CNV_8_HZ;
break;
case 250:
val = MAX31827_CNV_4_HZ;
break;
case 1000:
val = MAX31827_CNV_1_HZ;
break;
case 4000:
val = MAX31827_CNV_1_DIV_4_HZ;
break;
case 16000:
val = MAX31827_CNV_1_DIV_16_HZ;
break;
case 32000:
val = MAX31827_CNV_1_DIV_32_HZ;
break;
case 64000:
val = MAX31827_CNV_1_DIV_64_HZ;
break;
default:
return -EINVAL;
}
val = FIELD_PREP(MAX31827_CONFIGURATION_CNV_RATE_MASK,
val);
return regmap_update_bits(st->regmap,
MAX31827_CONFIGURATION_REG,
MAX31827_CONFIGURATION_CNV_RATE_MASK,
val);
}
break;
default:
return -EOPNOTSUPP;
}
return -EOPNOTSUPP;
}
static int max31827_init_client(struct max31827_state *st)
{
st->enable = true;
return regmap_update_bits(st->regmap, MAX31827_CONFIGURATION_REG,
MAX31827_CONFIGURATION_1SHOT_MASK |
MAX31827_CONFIGURATION_CNV_RATE_MASK,
MAX31827_DEVICE_ENABLE(1));
}
static const struct hwmon_channel_info *max31827_info[] = {
HWMON_CHANNEL_INFO(temp, HWMON_T_ENABLE | HWMON_T_INPUT | HWMON_T_MIN |
HWMON_T_MIN_HYST | HWMON_T_MIN_ALARM |
HWMON_T_MAX | HWMON_T_MAX_HYST |
HWMON_T_MAX_ALARM),
HWMON_CHANNEL_INFO(chip, HWMON_C_UPDATE_INTERVAL),
NULL,
};
static const struct hwmon_ops max31827_hwmon_ops = {
.is_visible = max31827_is_visible,
.read = max31827_read,
.write = max31827_write,
};
static const struct hwmon_chip_info max31827_chip_info = {
.ops = &max31827_hwmon_ops,
.info = max31827_info,
};
static int max31827_probe(struct i2c_client *client)
{
struct device *dev = &client->dev;
struct device *hwmon_dev;
struct max31827_state *st;
int err;
if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_WORD_DATA))
return -EOPNOTSUPP;
st = devm_kzalloc(dev, sizeof(*st), GFP_KERNEL);
if (!st)
return -ENOMEM;
mutex_init(&st->lock);
st->regmap = devm_regmap_init_i2c(client, &max31827_regmap);
if (IS_ERR(st->regmap))
return dev_err_probe(dev, PTR_ERR(st->regmap),
"Failed to allocate regmap.\n");
err = max31827_init_client(st);
if (err)
return err;
hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name, st,
&max31827_chip_info,
NULL);
return PTR_ERR_OR_ZERO(hwmon_dev);
}
static const struct i2c_device_id max31827_i2c_ids[] = {
{ "max31827", 0 },
{ }
};
MODULE_DEVICE_TABLE(i2c, max31827_i2c_ids);
static const struct of_device_id max31827_of_match[] = {
{ .compatible = "adi,max31827" },
{ }
};
MODULE_DEVICE_TABLE(of, max31827_of_match);
static struct i2c_driver max31827_driver = {
.class = I2C_CLASS_HWMON,
.driver = {
.name = "max31827",
.of_match_table = max31827_of_match,
},
.probe_new = max31827_probe,
.id_table = max31827_i2c_ids,
};
module_i2c_driver(max31827_driver);
MODULE_AUTHOR("Daniel Matyas <daniel.matyas@analog.com>");
MODULE_DESCRIPTION("Maxim MAX31827 low-power temperature switch driver");
MODULE_LICENSE("GPL");