[PATCH v2 2/2] [PATCH v1 2/2] hwmon: max31827: add MAX31827 driver
From: Daniel Matyas
Date: Wed Apr 12 2023 - 11:35:57 EST
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