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@xxxxxxxxxx> --- Documentation/hwmon/max31827.rst | 88 +++++++++ MAINTAINERS | 2 + drivers/hwmon/Kconfig | 11 ++ drivers/hwmon/Makefile | 1 + drivers/hwmon/max31827.c | 324 +++++++++++++++++++++++++++++++ 5 files changed, 426 insertions(+) create mode 100644 Documentation/hwmon/max31827.rst create mode 100644 drivers/hwmon/max31827.c diff --git a/Documentation/hwmon/max31827.rst b/Documentation/hwmon/max31827.rst new file mode 100644 index 000000000000..fe4d5bae8785 --- /dev/null +++ b/Documentation/hwmon/max31827.rst @@ -0,0 +1,88 @@ +.. 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@xxxxxxxxxx> + +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 implemets 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 (default) and interrupt mode. 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. + +In Interrupt mode exceeding TH also sets OT status to 1, which remains set until +a read operation is performed on the configuration/status register; at this +point, it returns to 0. Once OT status is set to 1 from exceeding TH and reset, +it is set to 1 again only when the temperature drops below TH_HYST. The output +remains asserted until it is reset by a read. It is set again if the temperature +rises above TH, and so on. The same logic applies to the operation of the UT +status bit. + +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 manuel with the one-shot functionality and automatic with +a set frequency. When powered on, the chip measures temperatures with 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. + + +Notes +----- + +Currently fault queue, alarm polarity and resolution cannot be modified. +PEC is not implemented either. diff --git a/MAINTAINERS b/MAINTAINERS index 8af1296ff1a0..cfb15f3f4606 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -12541,6 +12541,8 @@ L: linux-hwmon@xxxxxxxxxxxxxxx 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@xxxxxxxxxxxxxxx diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig index 5b3b76477b0e..80c44a787d42 100644 --- a/drivers/hwmon/Kconfig +++ b/drivers/hwmon/Kconfig @@ -2401,4 +2401,15 @@ config SENSORS_ASUS_EC endif # ACPI +config MAX31827 + tristate "MAX31827 low-power temperature switch" + depends on I2C + select REGMAP_I2C + help + If you say yes here you get support for MAX31827 + low-power temperature switch and sensor connected with I2C. + + This driver can also be built as a module. If so, the module + will be called max31827. + endif # HWMON diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile index 88712b5031c8..d00f0a1e73f6 100644 --- a/drivers/hwmon/Makefile +++ b/drivers/hwmon/Makefile @@ -224,3 +224,4 @@ obj-$(CONFIG_PMBUS) += pmbus/ ccflags-$(CONFIG_HWMON_DEBUG_CHIP) := -DDEBUG +obj-$(CONFIG_MAX31827) += max31827.o diff --git a/drivers/hwmon/max31827.c b/drivers/hwmon/max31827.c new file mode 100644 index 000000000000..8eb708adac49 --- /dev/null +++ b/drivers/hwmon/max31827.c @@ -0,0 +1,324 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * max31827.c - Support for Maxim Low-Power Switch + * + * Copyright (c) 2023 Daniel Matyas <daniel.matyas@xxxxxxxxxx> + */ + +#include <linux/bitfield.h> +#include <linux/delay.h> +#include <linux/hwmon.h> +#include <linux/i2c.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 140 + +#define MAX31827_DEVICE_ENABLE(x) ((x) ? 0xA : 0x0) + +enum chips { max31827, max31828, max31829 }; + +struct max31827_state { + 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, + unsigned int val) +{ + unsigned int cfg; + unsigned int tmp; + int ret; + + if (!st->enable) + return regmap_write(st->regmap, reg, val); + + ret = regmap_read(st->regmap, MAX31827_CONFIGURATION_REG, &cfg); + if (ret) + return ret; + + tmp = cfg & ~(MAX31827_CONFIGURATION_1SHOT_MASK | + MAX31827_CONFIGURATION_CNV_RATE_MASK); + ret = regmap_write(st->regmap, MAX31827_CONFIGURATION_REG, tmp); + if (ret) + return ret; + + ret = regmap_write(st->regmap, reg, val); + if (ret) + return ret; + + ret = regmap_write(st->regmap, MAX31827_CONFIGURATION_REG, cfg); + + 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; + } + } 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; + + switch (type) { + case hwmon_temp: + switch (attr) { + case hwmon_temp_enable: + ret = regmap_read(st->regmap, + MAX31827_CONFIGURATION_REG, &uval); + uval = FIELD_GET(MAX31827_CONFIGURATION_1SHOT_MASK | + MAX31827_CONFIGURATION_CNV_RATE_MASK, + uval); + if (uval) + uval = 1; + break; + case hwmon_temp_input: + if (!st->enable) { + ret = regmap_update_bits(st->regmap, + MAX31827_CONFIGURATION_REG, + MAX31827_CONFIGURATION_1SHOT_MASK, + 1); + if (ret) + return ret; + + msleep(MAX31827_12_BIT_CNV_TIME); + } + ret = regmap_read(st->regmap, MAX31827_T_REG, &uval); + + break; + case hwmon_temp_max: + ret = regmap_read(st->regmap, MAX31827_TH_REG, &uval); + break; + case hwmon_temp_max_hyst: + ret = regmap_read(st->regmap, MAX31827_TH_HYST_REG, + &uval); + break; + case hwmon_temp_max_alarm: + ret = regmap_read(st->regmap, + MAX31827_CONFIGURATION_REG, &uval); + uval = FIELD_GET(MAX31827_CONFIGURATION_O_TEMP_STAT_MASK, + uval); + break; + case hwmon_temp_min: + ret = regmap_read(st->regmap, MAX31827_TL_REG, &uval); + break; + case hwmon_temp_min_hyst: + ret = regmap_read(st->regmap, MAX31827_TL_HYST_REG, + &uval); + break; + case hwmon_temp_min_alarm: + ret = regmap_read(st->regmap, + MAX31827_CONFIGURATION_REG, &uval); + uval = FIELD_GET(MAX31827_CONFIGURATION_U_TEMP_STAT_MASK, + uval); + break; + default: + ret = -EOPNOTSUPP; + } + break; + + case hwmon_chip: + if (attr == hwmon_chip_update_interval) { + ret = regmap_read(st->regmap, + MAX31827_CONFIGURATION_REG, &uval); + uval = FIELD_GET(MAX31827_CONFIGURATION_CNV_RATE_MASK, + uval); + } + break; + + default: + ret = -EOPNOTSUPP; + } + + if (ret) + return ret; + + *val = (short)uval; + + return 0; +} + +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); + + switch (type) { + case hwmon_temp: + switch (attr) { + case hwmon_temp_enable: + if (val >> 1) + return -EOPNOTSUPP; + + st->enable = val; + + return regmap_update_bits(st->regmap, + MAX31827_CONFIGURATION_REG, + MAX31827_CONFIGURATION_1SHOT_MASK | + MAX31827_CONFIGURATION_CNV_RATE_MASK, + MAX31827_DEVICE_ENABLE(val)); + + 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) { + 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; + + 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", max31827 }, + { "max31828", max31828 }, + { "max31829", max31829 }, + { } +}; +MODULE_DEVICE_TABLE(i2c, max31827_i2c_ids); + +static const struct of_device_id max31827_of_match[] = { + { .compatible = "adi,max31827" }, + { .compatible = "adi,max31828" }, + { .compatible = "adi,max31829" }, + { } +}; +MODULE_DEVICE_TABLE(of, max31827_of_match); + +static struct i2c_driver max31827_driver = { + .class = I2C_CLASS_HWMON, + .driver = { + .name = "adi,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@xxxxxxxxxx>"); +MODULE_DESCRIPTION("Maxim MAX31827 low-power temperature switch driver"); +MODULE_LICENSE("GPL"); -- 2.34.1
