[PATCH 1/4] hwmon: Add driver for wsen tids-2521020222501

[Thomas Marangoni <Thomas.Marangoni@becom-group.com>]

This commit adds support for the wsen tids-2521020222501. It is a
low cost and small-form-factor i2c temperature sensor.

It supports the following features:
- Continuous temperature reading in four intervals: 5 ms, 10 ms,
  20 ms and 40 ms.
- Low temperature alarm
- High temperature alarm

The driver supports following hwmon features:
- hwmon_temp_input
- hwmon_temp_min_alarm
- hwmon_temp_max_alarm
- hwmon_temp_min_hyst
- hwmon_temp_max_hyst
- hwmon_chip_update_interval

Additional notes:
- The update interval only supports four fixed values.
- The alarm is reset on reading.
---
 drivers/hwmon/Kconfig  |  10 +
 drivers/hwmon/Makefile |   1 +
 drivers/hwmon/tids.c   | 560 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 571 insertions(+)
 create mode 100644 drivers/hwmon/tids.c

diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 8c852bcac26f..5e578241001f 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -2647,6 +2647,16 @@ config SENSORS_WM8350
 	  This driver can also be built as a module. If so, the module
 	  will be called wm8350-hwmon.
 
+config SENSORS_TIDS
+	tristate "TIDS"
+	depends on I2C
+	help
+	  If you say yes here you get support for the temperature
+	  sensor WSEN TIDS from Würth Elektronik.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called tids.
+
 config SENSORS_ULTRA45
 	tristate "Sun Ultra45 PIC16F747"
 	depends on SPARC64
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index a8de5bc69f2a..def052b2bdfa 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -244,6 +244,7 @@ obj-$(CONFIG_SENSORS_W83L785TS)	+= w83l785ts.o
 obj-$(CONFIG_SENSORS_W83L786NG)	+= w83l786ng.o
 obj-$(CONFIG_SENSORS_WM831X)	+= wm831x-hwmon.o
 obj-$(CONFIG_SENSORS_WM8350)	+= wm8350-hwmon.o
+obj-$(CONFIG_SENSORS_TIDS) += tids.o
 obj-$(CONFIG_SENSORS_XGENE)	+= xgene-hwmon.o
 
 obj-$(CONFIG_SENSORS_OCC)	+= occ/
diff --git a/drivers/hwmon/tids.c b/drivers/hwmon/tids.c
new file mode 100644
index 000000000000..0176a5e8b574
--- /dev/null
+++ b/drivers/hwmon/tids.c
@@ -0,0 +1,560 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+/*
+ * Copyright (c) BECOM Electronics GmbH
+ *
+ * wsen_tids_2521020222501.c - Linux hwmon driver for WSEN-TIDS
+ *                             2521020222501 Temperature sensor
+ *
+ * Author: Thomas Marangoni <thomas.marangoni@becom-group.com>
+ */
+
+#include <linux/bits.h>
+#include <linux/delay.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+/*
+ * TIDS registers
+ */
+#define TIDS_CMD_DEVICE_ID	0x01
+#define TIDS_CMD_T_H_LIMIT	0x02
+#define TIDS_CMD_T_L_LIMIT	0x03
+#define TIDS_CMD_CTRL		0x04
+#define TIDS_CMD_STATUS		0x05
+#define TIDS_CMD_DATA_T_L	0x06
+#define TIDS_CMD_DATA_T_H	0x07
+#define TIDS_CMD_SOFT_REST	0x0C
+
+/*
+ * TIDS device IDs
+ */
+#define TIDS_ID_2521020222501 0xa0
+
+enum tids_update_interval {
+	tids_update_interval_40ms = 0,
+	tids_update_interval_20ms = 1,
+	tids_update_interval_10ms = 2,
+	tids_update_interval_5ms = 3,
+};
+
+/* TIDS control register */
+static const struct reg_field tids_reg_field_ctrl_one_shot =
+	REG_FIELD(TIDS_CMD_CTRL, 0, 0);
+static const struct reg_field tids_reg_field_ctrl_freerun =
+	REG_FIELD(TIDS_CMD_CTRL, 2, 2);
+static const struct reg_field tids_reg_field_ctrl_if_add_inc =
+	REG_FIELD(TIDS_CMD_CTRL, 3, 3);
+static const struct reg_field tids_reg_field_ctrl_avg =
+	REG_FIELD(TIDS_CMD_CTRL, 4, 5);
+static const struct reg_field tids_reg_field_ctrl_bdu =
+	REG_FIELD(TIDS_CMD_CTRL, 6, 6);
+/* TIDS status register */
+static const struct reg_field tids_reg_field_status_busy =
+	REG_FIELD(TIDS_CMD_STATUS, 0, 0);
+static const struct reg_field tids_reg_field_status_over_thl =
+	REG_FIELD(TIDS_CMD_STATUS, 1, 1);
+static const struct reg_field tids_reg_field_status_under_tll =
+	REG_FIELD(TIDS_CMD_STATUS, 2, 2);
+/* TIDS reset register */
+static const struct reg_field tids_reg_field_soft_reset =
+	REG_FIELD(TIDS_CMD_SOFT_REST, 1, 1);
+
+struct tids_data {
+	struct i2c_client *client;
+
+	struct regmap *regmap;
+
+	/* regmap field for ctrl register */
+	struct regmap_field *reg_ctrl_one_shot;
+	struct regmap_field *reg_ctrl_freerun;
+	struct regmap_field *reg_ctrl_if_add_inc;
+	struct regmap_field *reg_ctrl_avg;
+	struct regmap_field *reg_ctrl_bdu;
+
+	/* regmap field for status register */
+	struct regmap_field *reg_status_busy;
+	struct regmap_field *reg_status_over_thl;
+	struct regmap_field *reg_status_under_tll;
+
+	/* regmap field for soft reset register*/
+	struct regmap_field *reg_soft_reset;
+
+	int irq;
+	int temperature;
+};
+
+static ssize_t tids_interval_read(struct device *dev, long *val)
+{
+	int ret = 0;
+	unsigned int avg_value = 0;
+	struct tids_data *data = dev_get_drvdata(dev);
+
+	ret = regmap_field_read(data->reg_ctrl_avg, &avg_value);
+	if (ret < 0)
+		return ret;
+
+	switch (avg_value) {
+	case tids_update_interval_40ms:
+		*val = 40;
+		break;
+	case tids_update_interval_20ms:
+		*val = 20;
+		break;
+	case tids_update_interval_10ms:
+		*val = 10;
+		break;
+	case tids_update_interval_5ms:
+		*val = 5;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static ssize_t tids_interval_write(struct device *dev, long val)
+{
+	unsigned int avg_value = 0;
+	struct tids_data *data = dev_get_drvdata(dev);
+
+	switch (val) {
+	case 40:
+		avg_value = tids_update_interval_40ms;
+		break;
+	case 20:
+		avg_value = tids_update_interval_20ms;
+		break;
+	case 10:
+		avg_value = tids_update_interval_10ms;
+		break;
+	case 5:
+		avg_value = tids_update_interval_5ms;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return regmap_field_write(data->reg_ctrl_avg, avg_value);
+}
+
+static int tids_temperature1_read(struct device *dev, long *val)
+{
+	int ret;
+	u8 buf[2] = { 0 };
+	struct tids_data *data = dev_get_drvdata(dev);
+
+	ret = regmap_bulk_read(data->regmap, TIDS_CMD_DATA_T_L, buf, 2);
+	if (ret < 0)
+		return ret;
+
+	// temperature in °mC
+	*val = (((s16)(buf[1] << 8) | buf[0])) * 10;
+
+	return 0;
+}
+
+static ssize_t tids_temperature_alarm_read(struct device *dev, u32 attr,
+					   long *val)
+{
+	int ret = 0;
+	unsigned int reg_data = 0;
+	struct tids_data *data = dev_get_drvdata(dev);
+
+	if (attr == hwmon_temp_min_alarm)
+		ret = regmap_field_read(data->reg_status_under_tll, &reg_data);
+	else if (attr == hwmon_temp_max_alarm)
+		ret = regmap_field_read(data->reg_status_over_thl, &reg_data);
+	else
+		return -EOPNOTSUPP;
+
+	if (ret < 0)
+		return ret;
+
+	*val = reg_data;
+
+	return 0;
+}
+
+static int tids_temperature_hyst_read(struct device *dev, u32 attr, long *val)
+{
+	int ret;
+	struct tids_data *data = dev_get_drvdata(dev);
+	unsigned int reg_data = 0;
+
+	if (attr == hwmon_temp_min_hyst)
+		ret = regmap_read(data->regmap, TIDS_CMD_T_L_LIMIT, &reg_data);
+	else if (attr == hwmon_temp_max_hyst)
+		ret = regmap_read(data->regmap, TIDS_CMD_T_H_LIMIT, &reg_data);
+	else
+		return -EOPNOTSUPP;
+
+	if (ret < 0)
+		return ret;
+
+	// temperature from register conversion in °mC
+	*val = (((u8)reg_data - 63) * 640);
+
+	return 0;
+}
+
+static ssize_t tids_temperature_hyst_write(struct device *dev, u32 attr,
+					   long val)
+{
+	u8 reg_data = 0;
+	struct tids_data *data = dev_get_drvdata(dev);
+
+	// temperature in °mC
+	if (val < -39680 || val > 122880)
+		return -EINVAL;
+
+	// temperature to register conversion in °mC
+	reg_data = (u8)((val / 640) + 63);
+
+	if (attr == hwmon_temp_min_hyst)
+		return regmap_write(data->regmap, TIDS_CMD_T_L_LIMIT, reg_data);
+	else if (attr == hwmon_temp_max_hyst)
+		return regmap_write(data->regmap, TIDS_CMD_T_H_LIMIT, reg_data);
+	else
+		return -EOPNOTSUPP;
+}
+
+static umode_t tids_hwmon_visible(const void *data,
+				  enum hwmon_sensor_types type, u32 attr,
+				  int channel)
+{
+	umode_t mode = 0;
+
+	switch (type) {
+	case hwmon_temp:
+		switch (attr) {
+		case hwmon_temp_input:
+		case hwmon_temp_min_alarm:
+		case hwmon_temp_max_alarm:
+			mode = 0444;
+			break;
+		case hwmon_temp_min_hyst:
+		case hwmon_temp_max_hyst:
+			mode = 0644;
+			break;
+		default:
+			break;
+		}
+		break;
+	case hwmon_chip:
+		switch (attr) {
+		case hwmon_chip_update_interval:
+			mode = 0644;
+			break;
+		default:
+			break;
+		}
+		break;
+	default:
+		break;
+	}
+
+	return mode;
+}
+
+static int tids_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
+			   u32 attr, int channel, long *val)
+{
+	switch (type) {
+	case hwmon_temp:
+		switch (attr) {
+		case hwmon_temp_input:
+			return tids_temperature1_read(dev, val);
+		case hwmon_temp_min_alarm:
+		case hwmon_temp_max_alarm:
+			return tids_temperature_alarm_read(dev, attr, val);
+		case hwmon_temp_min_hyst:
+		case hwmon_temp_max_hyst:
+			return tids_temperature_hyst_read(dev, attr, val);
+		default:
+			return -EOPNOTSUPP;
+		}
+	case hwmon_chip:
+		switch (attr) {
+		case hwmon_chip_update_interval:
+			return tids_interval_read(dev, val);
+		default:
+			return -EOPNOTSUPP;
+		}
+	default:
+		return -EOPNOTSUPP;
+	}
+}
+
+static int tids_hwmon_write(struct device *dev, enum hwmon_sensor_types type,
+			    u32 attr, int channel, long val)
+{
+	switch (type) {
+	case hwmon_temp:
+		switch (attr) {
+		case hwmon_temp_min_hyst:
+		case hwmon_temp_max_hyst:
+			return tids_temperature_hyst_write(dev, attr, val);
+		default:
+			return -EOPNOTSUPP;
+		}
+	case hwmon_chip:
+		switch (attr) {
+		case hwmon_chip_update_interval:
+			return tids_interval_write(dev, val);
+		default:
+			return -EOPNOTSUPP;
+		}
+	default:
+		return -EOPNOTSUPP;
+	}
+}
+
+static const struct hwmon_channel_info *const tids_info[] = {
+	HWMON_CHANNEL_INFO(chip, HWMON_C_UPDATE_INTERVAL),
+	HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT | HWMON_T_MIN_ALARM |
+					 HWMON_T_MAX_ALARM | HWMON_T_MIN_HYST |
+					 HWMON_T_MAX_HYST),
+	NULL
+};
+
+static const struct hwmon_ops tids_ops = {
+	.is_visible = tids_hwmon_visible,
+	.read		= tids_hwmon_read,
+	.write		= tids_hwmon_write,
+};
+
+static const struct hwmon_chip_info tids_chip_info = {
+	.ops	= &tids_ops,
+	.info	= tids_info,
+};
+
+static bool tids_regmap_writeable_reg(struct device *dev, unsigned int reg)
+{
+	if (reg >= 0x02 && reg <= 0x04)
+		return true;
+
+	if (reg == 0x0c)
+		return true;
+
+	return false;
+}
+
+static bool tids_regmap_readable_reg(struct device *dev, unsigned int reg)
+{
+	if (reg >= 0x01 && reg <= 0x07)
+		return true;
+
+	if (reg == 0x0c)
+		return true;
+
+	return false;
+}
+
+static bool tids_regmap_volatile_reg(struct device *dev, unsigned int reg)
+{
+	if (reg >= 0x05 && reg <= 0x07)
+		return true;
+
+	if (reg == 0x0c)
+		return true;
+
+	return false;
+}
+
+static const struct regmap_config regmap_config = {
+	.reg_bits			= 8,
+	.val_bits			= 8,
+	.max_register		= TIDS_CMD_SOFT_REST,
+	.writeable_reg		= tids_regmap_writeable_reg,
+	.readable_reg		= tids_regmap_readable_reg,
+	.volatile_reg		= tids_regmap_volatile_reg,
+	.use_single_read	= 0,
+};
+
+static int tids_probe_regmap(struct tids_data *data)
+{
+	struct device *dev = &data->client->dev;
+
+	/* Init regmap */
+	data->regmap = devm_regmap_init_i2c(data->client, &regmap_config);
+	if (IS_ERR(data->regmap))
+		return dev_err_probe(dev, PTR_ERR(data->regmap),
+				     "regmap initialization failed\n");
+
+	/* Allocate regmap_field for ctrl register */
+	data->reg_ctrl_one_shot = devm_regmap_field_alloc(
+		dev, data->regmap, tids_reg_field_ctrl_one_shot);
+	if (IS_ERR(data->reg_ctrl_one_shot))
+		return dev_err_probe(
+			dev, PTR_ERR(data->reg_ctrl_one_shot),
+			"regmap_field reg_ctrl_one_shot initialization failed\n");
+
+	data->reg_ctrl_freerun = devm_regmap_field_alloc(
+		dev, data->regmap, tids_reg_field_ctrl_freerun);
+	if (IS_ERR(data->reg_ctrl_freerun))
+		return dev_err_probe(
+			dev, PTR_ERR(data->reg_ctrl_freerun),
+			"regmap_field reg_ctrl_freerun initialization failed\n");
+
+	data->reg_ctrl_if_add_inc = devm_regmap_field_alloc(
+		dev, data->regmap, tids_reg_field_ctrl_if_add_inc);
+	if (IS_ERR(data->reg_ctrl_if_add_inc))
+		return dev_err_probe(
+			dev, PTR_ERR(data->reg_ctrl_if_add_inc),
+			"regmap_field reg_ctrl_if_add_inc initialization failed\n");
+
+	data->reg_ctrl_avg = devm_regmap_field_alloc(dev, data->regmap,
+						     tids_reg_field_ctrl_avg);
+	if (IS_ERR(data->reg_ctrl_avg))
+		return dev_err_probe(
+			dev, PTR_ERR(data->reg_ctrl_avg),
+			"regmap_field reg_ctrl_avg initialization failed\n");
+
+	data->reg_ctrl_bdu = devm_regmap_field_alloc(dev, data->regmap,
+						     tids_reg_field_ctrl_bdu);
+	if (IS_ERR(data->reg_ctrl_bdu))
+		return dev_err_probe(
+			dev, PTR_ERR(data->reg_ctrl_bdu),
+			"regmap_field reg_ctrl_bdu initialization failed\n");
+
+	/* Allocate regmap_field for status register */
+	data->reg_status_busy = devm_regmap_field_alloc(
+		dev, data->regmap, tids_reg_field_status_busy);
+	if (IS_ERR(data->reg_status_busy))
+		return dev_err_probe(
+			dev, PTR_ERR(data->reg_status_busy),
+			"regmap_field reg_status_busy initialization failed\n");
+
+	data->reg_status_over_thl = devm_regmap_field_alloc(
+		dev, data->regmap, tids_reg_field_status_over_thl);
+	if (IS_ERR(data->reg_status_over_thl))
+		return dev_err_probe(
+			dev, PTR_ERR(data->reg_status_over_thl),
+			"regmap_field reg_status_over_thl initialization failed\n");
+
+	data->reg_status_under_tll = devm_regmap_field_alloc(
+		dev, data->regmap, tids_reg_field_status_under_tll);
+	if (IS_ERR(data->reg_status_under_tll))
+		return dev_err_probe(
+			dev, PTR_ERR(data->reg_status_under_tll),
+			"regmap_field reg_status_under_tll initialization failed\n");
+
+	/* Allocate regmap_field for software_reset */
+	data->reg_soft_reset = devm_regmap_field_alloc(
+		dev, data->regmap, tids_reg_field_soft_reset);
+	if (IS_ERR(data->reg_soft_reset))
+		return dev_err_probe(
+			dev, PTR_ERR(data->reg_soft_reset),
+			"regmap_field reg_soft_reset initialization failed\n");
+
+	return 0;
+}
+
+static int tids_probe(struct i2c_client *client)
+{
+	struct device *device = &client->dev;
+	struct device *hwmon_dev;
+	struct tids_data *data;
+	unsigned int value;
+	int ret = 0;
+
+	data = devm_kzalloc(device, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->client = client;
+
+	ret = tids_probe_regmap(data);
+	if (ret != 0)
+		return ret;
+
+	/* Read device id, to check if i2c is working */
+	ret = regmap_read(data->regmap, TIDS_CMD_DEVICE_ID, &value);
+	if (ret < 0)
+		return ret;
+
+	/* Triggering soft reset */
+	ret = regmap_field_write(data->reg_soft_reset, 1);
+	if (ret < 0)
+		return ret;
+
+	ret = regmap_field_write(data->reg_soft_reset, 0);
+	if (ret < 0)
+		return ret;
+
+	/* Allowing bulk read */
+	ret = regmap_field_write(data->reg_ctrl_if_add_inc, 1);
+	if (ret < 0)
+		return ret;
+
+	/* Set meassurement interval */
+	ret = regmap_field_write(data->reg_ctrl_avg, tids_update_interval_40ms);
+	if (ret < 0)
+		return ret;
+
+	/* Set device to free run mode */
+	ret = regmap_field_write(data->reg_ctrl_freerun, 1);
+	if (ret < 0)
+		return ret;
+
+	/* Don't update temperature register until high and low value are read */
+	ret = regmap_field_write(data->reg_ctrl_bdu, 1);
+	if (ret < 0)
+		return ret;
+
+	hwmon_dev = devm_hwmon_device_register_with_info(
+		device, device->driver->name, data, &tids_chip_info, NULL);
+
+	return PTR_ERR_OR_ZERO(hwmon_dev);
+}
+
+static int tids_suspend(struct device *dev)
+{
+	struct tids_data *data = dev_get_drvdata(dev);
+
+	return regmap_field_write(data->reg_ctrl_freerun, 0);
+}
+
+static int tids_resume(struct device *dev)
+{
+	struct tids_data *data = dev_get_drvdata(dev);
+
+	return regmap_field_write(data->reg_ctrl_freerun, 1);
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(tids_dev_pm_ops, tids_resume, tids_suspend);
+
+static const struct i2c_device_id tids_id[] = {
+	{ "tids", 0 },
+	{},
+};
+MODULE_DEVICE_TABLE(i2c, tids_id);
+
+static const struct of_device_id tids_of_match[] = {
+	{ .compatible = "wsen,tids-2521020222501" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, tids_of_match);
+
+static struct i2c_driver tids_driver = {
+	.class	= I2C_CLASS_HWMON,
+	.driver = {
+		.name			= "tids",
+		.pm				= pm_sleep_ptr(&tids_dev_pm_ops),
+		.of_match_table = tids_of_match,
+	},
+	.probe		= tids_probe,
+	.id_table	= tids_id,
+};
+
+module_i2c_driver(tids_driver);
+
+MODULE_AUTHOR("Thomas Marangoni <Thomas.Marangoni@becom-group.com>");
+MODULE_DESCRIPTION("WSEN TIDS temperature sensor driver");
+MODULE_LICENSE("GPL");
-- 
2.51.1