hwmon: Add driver for Renesas HS3001

Add base support for Renesas HS3001 temperature
and humidity sensors and its compatibles HS3002,
HS3003 and HS3004.

The sensor has a fix I2C address 0x44. The resolution
is fixed to 14bit (ref. Missing feature).

Missing feature:
- Accessing non-volatile memory: Custom board has no
  possibility to control voltage supply of sensor. Thus,
  we cannot send the necessary control commands within
  the first 10ms after power-on.

Signed-off-by: Andre Werner <andre.werner@systec-electronic.com>
Link: https://lore.kernel.org/r/20230725042207.22310-2-andre.werner@systec-electronic.com
[groeck: Cosmetic documentation fixup; added documentation to index;
 replaced probe_new with probe dropped unused variable]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

6 files changed, 297 insertions, 0 deletions

diff --git a/Documentation/hwmon/hs3001.rst b/Documentation/hwmon/hs3001.rst
new file mode 100644
index 000000000000..9f59dfc212d9
--- /dev/null
+++ b/Documentation/hwmon/hs3001.rst
@@ -0,0 +1,37 @@
+.. SPDX-License-Identifier: GPL-2.0-or-later
+
+Kernel driver HS3001
+====================
+
+Supported chips:
+
+  * Renesas HS3001, HS3002, HS3003, HS3004
+
+    Prefix: 'hs3001'
+
+    Addresses scanned: -
+
+    Datasheet: https://www.renesas.com/us/en/document/dst/hs300x-datasheet?r=417401
+
+Author:
+
+  - Andre Werner <andre.werner@systec-electronic.com>
+
+Description
+-----------
+
+This driver implements support for the Renesas HS3001 chips, a humidity
+and temperature family. Temperature is measured in degrees celsius, relative
+humidity is expressed as a percentage. In the sysfs interface, all values are
+scaled by 1000, i.e. the value for 31.5 degrees celsius is 31500.
+
+The device communicates with the I2C protocol. Sensors have the I2C
+address 0x44 by default.
+
+sysfs-Interface
+---------------
+
+=================== =================
+temp1_input:        temperature input
+humidity1_input:    humidity input
+=================== =================
diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
index d11924667f76..88dadea85cfc 100644
--- a/Documentation/hwmon/index.rst
+++ b/Documentation/hwmon/index.rst
@@ -78,6 +78,7 @@ Hardware Monitoring Kernel Drivers
    gxp-fan-ctrl
    hih6130
    hp-wmi-sensors
+   hs3001
    ibmaem
    ibm-cffps
    ibmpowernv
diff --git a/MAINTAINERS b/MAINTAINERS
index 080e39424343..2c163adcda2d 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -9497,6 +9497,12 @@ S:	Maintained
 W:	http://artax.karlin.mff.cuni.cz/~mikulas/vyplody/hpfs/index-e.cgi
 F:	fs/hpfs/
 
+HS3001 Hardware Temperature and Humidity Sensor
+M:	Andre Werner <andre.werner@systec-electronic.com>
+L:	linux-hwmon@vger.kernel.org
+S:	Maintained
+F:	drivers/hwmon/hs3001.c
+
 HSI SUBSYSTEM
 M:	Sebastian Reichel <sre@kernel.org>
 S:	Maintained
diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 2913299c2c9e..ec38c8892158 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -734,6 +734,16 @@ config SENSORS_HIH6130
 	  This driver can also be built as a module. If so, the module
 	  will be called hih6130.
 
+config SENSORS_HS3001
+	tristate "Renesas HS3001 humidity and temperature sensors"
+	depends on I2C
+	help
+	  If you say yes here you get support for the Renesas HS3001,
+	  to HS3004 humidity and temperature sensors.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called hs3001.
+
 config SENSORS_IBMAEM
 	tristate "IBM Active Energy Manager temperature/power sensors and control"
 	select IPMI_SI
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index ff6bfd109c72..4ac9452b5430 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -86,6 +86,7 @@ obj-$(CONFIG_SENSORS_GSC)	+= gsc-hwmon.o
 obj-$(CONFIG_SENSORS_GPIO_FAN)	+= gpio-fan.o
 obj-$(CONFIG_SENSORS_GXP_FAN_CTRL) += gxp-fan-ctrl.o
 obj-$(CONFIG_SENSORS_HIH6130)	+= hih6130.o
+obj-$(CONFIG_SENSORS_HS3001)	+= hs3001.o
 obj-$(CONFIG_SENSORS_ULTRA45)	+= ultra45_env.o
 obj-$(CONFIG_SENSORS_I5500)	+= i5500_temp.o
 obj-$(CONFIG_SENSORS_I5K_AMB)	+= i5k_amb.o
diff --git a/drivers/hwmon/hs3001.c b/drivers/hwmon/hs3001.c
new file mode 100644
index 000000000000..ac574e46d069
--- /dev/null
+++ b/drivers/hwmon/hs3001.c
@@ -0,0 +1,242 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * This is a non-complete driver implementation for the
+ * HS3001 humidity and temperature sensor and compatibles. It does not include
+ * the configuration possibilities, where it needs to be set to 'programming mode'
+ * during power-up.
+ *
+ *
+ * Copyright (C) 2023 SYS TEC electronic AG
+ * Author: Andre Werner <andre.werner@systec-electronic.com>
+ */
+
+#include <linux/bitfield.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/hwmon.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+
+/* Measurement times */
+#define HS3001_WAKEUP_TIME	100	/* us */
+#define HS3001_8BIT_RESOLUTION	550	/* us */
+#define HS3001_10BIT_RESOLUTION	1310	/* us */
+#define HS3001_12BIT_RESOLUTION	4500	/* us */
+#define HS3001_14BIT_RESOLUTION	16900	/* us */
+
+#define HS3001_RESPONSE_LENGTH	4
+
+#define HS3001_FIXPOINT_ARITH	1000U
+
+#define HS3001_MASK_HUMIDITY_0X3FFF	GENMASK(13, 0)
+#define HS3001_MASK_STATUS_0XC0	GENMASK(7, 6)
+
+/* Definitions for Status Bits of A/D Data */
+#define HS3001_DATA_VALID	0x00	/* Valid Data */
+#define HS3001_DATA_STALE	0x01	/* Stale Data */
+
+struct hs3001_data {
+	struct i2c_client *client;
+	struct mutex i2c_lock; /* lock for sending i2c commands */
+	u32 wait_time;		/* in us */
+	int temperature;	/* in milli degree */
+	u32 humidity;		/* in milli % */
+};
+
+static int hs3001_extract_temperature(u16 raw)
+{
+	/* fixpoint arithmetic 1 digit */
+	u32 temp = (raw >> 2) * HS3001_FIXPOINT_ARITH * 165;
+
+	temp /= (1 << 14) - 1;
+
+	return (int)temp - 40 * HS3001_FIXPOINT_ARITH;
+}
+
+static u32 hs3001_extract_humidity(u16 raw)
+{
+	u32 hum = (raw & HS3001_MASK_HUMIDITY_0X3FFF) * HS3001_FIXPOINT_ARITH * 100;
+
+	return hum /= (1 << 14) - 1;
+}
+
+static int hs3001_data_fetch_command(struct i2c_client *client,
+				     struct hs3001_data *data)
+{
+	int ret;
+	u8 buf[HS3001_RESPONSE_LENGTH];
+	u8 hs3001_status;
+
+	ret = i2c_master_recv(client, buf, HS3001_RESPONSE_LENGTH);
+	if (ret != HS3001_RESPONSE_LENGTH) {
+		ret = ret < 0 ? ret : -EIO;
+		dev_dbg(&client->dev,
+			"Error in i2c communication. Error code: %d.\n", ret);
+		return ret;
+	}
+
+	hs3001_status = FIELD_GET(HS3001_MASK_STATUS_0XC0, buf[0]);
+	if (hs3001_status == HS3001_DATA_STALE) {
+		dev_dbg(&client->dev, "Sensor busy.\n");
+		return -EBUSY;
+	}
+	if (hs3001_status != HS3001_DATA_VALID) {
+		dev_dbg(&client->dev, "Data invalid.\n");
+		return -EIO;
+	}
+
+	data->humidity =
+		hs3001_extract_humidity(be16_to_cpup((__be16 *)&buf[0]));
+	data->temperature =
+		hs3001_extract_temperature(be16_to_cpup((__be16 *)&buf[2]));
+
+	return 0;
+}
+
+static umode_t hs3001_is_visible(const void *data, enum hwmon_sensor_types type,
+				 u32 attr, int channel)
+{
+	/* Both, humidity and temperature can only be read. */
+	return 0444;
+}
+
+static int hs3001_read(struct device *dev, enum hwmon_sensor_types type,
+		       u32 attr, int channel, long *val)
+{
+	struct hs3001_data *data = dev_get_drvdata(dev);
+	struct i2c_client *client = data->client;
+	int ret;
+
+	mutex_lock(&data->i2c_lock);
+	ret = i2c_master_send(client, NULL, 0);
+	if (ret < 0) {
+		mutex_unlock(&data->i2c_lock);
+		return ret;
+	}
+
+	/*
+	 * Sensor needs some time to process measurement depending on
+	 * resolution (ref. datasheet)
+	 */
+	fsleep(data->wait_time);
+
+	ret = hs3001_data_fetch_command(client, data);
+	mutex_unlock(&data->i2c_lock);
+
+	if (ret < 0)
+		return ret;
+
+	switch (type) {
+	case hwmon_temp:
+		switch (attr) {
+		case hwmon_temp_input:
+			*val = data->temperature;
+			break;
+		default:
+			return -EINVAL;
+		}
+		break;
+	case hwmon_humidity:
+		switch (attr) {
+		case hwmon_humidity_input:
+			*val = data->humidity;
+			break;
+		default:
+			return -EINVAL;
+		}
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static const struct hwmon_channel_info *hs3001_info[] = {
+	HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT),
+	HWMON_CHANNEL_INFO(humidity, HWMON_H_INPUT),
+	NULL
+};
+
+static const struct hwmon_ops hs3001_hwmon_ops = {
+	.is_visible = hs3001_is_visible,
+	.read = hs3001_read,
+};
+
+static const struct hwmon_chip_info hs3001_chip_info = {
+	.ops = &hs3001_hwmon_ops,
+	.info = hs3001_info,
+};
+
+/* device ID table */
+static const struct i2c_device_id hs3001_ids[] = {
+	{ "hs3001", 0 },
+	{ },
+};
+
+MODULE_DEVICE_TABLE(i2c, hs3001_ids);
+
+static const struct of_device_id hs3001_of_match[] = {
+	{.compatible = "renesas,hs3001"},
+	{ },
+};
+
+MODULE_DEVICE_TABLE(of, hs3001_of_match);
+
+static int hs3001_probe(struct i2c_client *client)
+{
+	struct hs3001_data *data;
+	struct device *hwmon_dev;
+	struct device *dev = &client->dev;
+
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
+		return -EOPNOTSUPP;
+
+	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->client = client;
+
+	/*
+	 * Measurement time = wake-up time + measurement time temperature
+	 * + measurement time humidity. This is currently static, because
+	 * enabling programming mode is not supported, yet.
+	 */
+	data->wait_time = (HS3001_WAKEUP_TIME + HS3001_14BIT_RESOLUTION +
+			   HS3001_14BIT_RESOLUTION);
+
+	mutex_init(&data->i2c_lock);
+
+	hwmon_dev = devm_hwmon_device_register_with_info(dev,
+							 client->name,
+							 data,
+							 &hs3001_chip_info,
+							 NULL);
+
+	if (IS_ERR(hwmon_dev))
+		return dev_err_probe(dev, PTR_ERR(hwmon_dev),
+				     "Unable to register hwmon device.\n");
+
+	return 0;
+}
+
+static struct i2c_driver hs3001_i2c_driver = {
+	.driver = {
+		   .name = "hs3001",
+		   .of_match_table = hs3001_of_match,
+	},
+	.probe = hs3001_probe,
+	.id_table = hs3001_ids,
+};
+
+module_i2c_driver(hs3001_i2c_driver);
+
+MODULE_AUTHOR("Andre Werner <andre.werner@systec-electronic.com>");
+MODULE_DESCRIPTION("HS3001 humidity and temperature sensor base driver");
+MODULE_LICENSE("GPL");