hwmon: (htu21) Remove driver

HTU21 is now supported by IIO, and can be instantiated as hwmon driver
using the iio-hwmon bridge. An explicit hwmon driver is no longer needed.

Cc: William Markezana <william.markezana@meas-spec.com>
Cc: Ludovic Tancerel <ludovic.tancerel@maplehightech.com>
Cc: Jonathan Cameron <jic23@kernel.org>
Reviewed-by: Jean Delvare <jdelvare@suse.de>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Documentation/hwmon/htu21

-Kernel driver htu21
-===================
-
-Supported chips:
-  * Measurement Specialties HTU21D
-    Prefix: 'htu21'
-    Addresses scanned: none
-    Datasheet: Publicly available at the Measurement Specialties website
-    http://www.meas-spec.com/downloads/HTU21D.pdf
-
-
-Author:
-  William Markezana <william.markezana@meas-spec.com>
-
-Description
------------
-
-The HTU21D is a humidity and temperature sensor in a DFN package of
-only 3 x 3 mm footprint and 0.9 mm height.
-
-The devices communicate with the I2C protocol. All sensors are set to the
-same I2C address 0x40, so an entry with I2C_BOARD_INFO("htu21", 0x40) can
-be used in the board setup code.
-
-This driver does not auto-detect devices. You will have to instantiate the
-devices explicitly. Please see Documentation/i2c/instantiating-devices
-for details.
-
-sysfs-Interface
----------------
-
-temp1_input - temperature input
-humidity1_input - humidity input
-
-Notes
------
-
-The driver uses the default resolution settings of 12 bit for humidity and 14
-bit for temperature, which results in typical measurement times of 11 ms for
-humidity and 44 ms for temperature. To keep self heating below 0.1 degree
-Celsius, the device should not be active for more than 10% of the time. For
-this reason, the driver performs no more than two measurements per second and
-reports cached information if polled more frequently.
-
-Different resolutions, the on-chip heater, using the CRC checksum and reading
-the serial number are not supported yet.

drivers/hwmon/Kconfig

@@ -859,16 +859,6 @@ config SENSORS_MAX31790
 	  This driver can also be built as a module.  If so, the module
 	  will be called max31790.
 
-config SENSORS_HTU21
-	tristate "Measurement Specialties HTU21D humidity/temperature sensors"
-	depends on I2C
-	help
-	  If you say yes here you get support for the Measurement Specialties
-	  HTU21D humidity and temperature sensors.
-
-	  This driver can also be built as a module.  If so, the module
-	  will be called htu21.
-
 config SENSORS_MCP3021
 	tristate "Microchip MCP3021 and compatibles"
 	depends on I2C

drivers/hwmon/Makefile

@@ -68,7 +68,6 @@ obj-$(CONFIG_SENSORS_GL518SM)	+= gl518sm.o
 obj-$(CONFIG_SENSORS_GL520SM)	+= gl520sm.o
 obj-$(CONFIG_SENSORS_GPIO_FAN)	+= gpio-fan.o
 obj-$(CONFIG_SENSORS_HIH6130)	+= hih6130.o
-obj-$(CONFIG_SENSORS_HTU21)	+= htu21.o
 obj-$(CONFIG_SENSORS_ULTRA45)	+= ultra45_env.o
 obj-$(CONFIG_SENSORS_I5500)	+= i5500_temp.o
 obj-$(CONFIG_SENSORS_I5K_AMB)	+= i5k_amb.o

drivers/hwmon/htu21.c

-/*
- * Measurement Specialties HTU21D humidity and temperature sensor driver
- *
- * Copyright (C) 2013 William Markezana <william.markezana@meas-spec.com>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- */
-
-#include <linux/module.h>
-#include <linux/init.h>
-#include <linux/slab.h>
-#include <linux/i2c.h>
-#include <linux/hwmon.h>
-#include <linux/hwmon-sysfs.h>
-#include <linux/err.h>
-#include <linux/mutex.h>
-#include <linux/device.h>
-#include <linux/jiffies.h>
-
-/* HTU21 Commands */
-#define HTU21_T_MEASUREMENT_HM	0xE3
-#define HTU21_RH_MEASUREMENT_HM	0xE5
-
-struct htu21 {
-	struct i2c_client *client;
-	struct mutex lock;
-	bool valid;
-	unsigned long last_update;
-	int temperature;
-	int humidity;
-};
-
-static inline int htu21_temp_ticks_to_millicelsius(int ticks)
-{
-	ticks &= ~0x0003; /* clear status bits */
-	/*
-	 * Formula T = -46.85 + 175.72 * ST / 2^16 from datasheet p14,
-	 * optimized for integer fixed point (3 digits) arithmetic
-	 */
-	return ((21965 * ticks) >> 13) - 46850;
-}
-
-static inline int htu21_rh_ticks_to_per_cent_mille(int ticks)
-{
-	ticks &= ~0x0003; /* clear status bits */
-	/*
-	 * Formula RH = -6 + 125 * SRH / 2^16 from datasheet p14,
-	 * optimized for integer fixed point (3 digits) arithmetic
-	 */
-	return ((15625 * ticks) >> 13) - 6000;
-}
-
-static int htu21_update_measurements(struct device *dev)
-{
-	struct htu21 *htu21 = dev_get_drvdata(dev);
-	struct i2c_client *client = htu21->client;
-	int ret = 0;
-
-	mutex_lock(&htu21->lock);
-
-	if (time_after(jiffies, htu21->last_update + HZ / 2) ||
-	    !htu21->valid) {
-		ret = i2c_smbus_read_word_swapped(client,
-						  HTU21_T_MEASUREMENT_HM);
-		if (ret < 0)
-			goto out;
-		htu21->temperature = htu21_temp_ticks_to_millicelsius(ret);
-		ret = i2c_smbus_read_word_swapped(client,
-						  HTU21_RH_MEASUREMENT_HM);
-		if (ret < 0)
-			goto out;
-		htu21->humidity = htu21_rh_ticks_to_per_cent_mille(ret);
-		htu21->last_update = jiffies;
-		htu21->valid = true;
-	}
-out:
-	mutex_unlock(&htu21->lock);
-
-	return ret >= 0 ? 0 : ret;
-}
-
-static ssize_t htu21_show_temperature(struct device *dev,
-				      struct device_attribute *attr, char *buf)
-{
-	struct htu21 *htu21 = dev_get_drvdata(dev);
-	int ret;
-
-	ret = htu21_update_measurements(dev);
-	if (ret < 0)
-		return ret;
-	return sprintf(buf, "%d\n", htu21->temperature);
-}
-
-static ssize_t htu21_show_humidity(struct device *dev,
-				   struct device_attribute *attr, char *buf)
-{
-	struct htu21 *htu21 = dev_get_drvdata(dev);
-	int ret;
-
-	ret = htu21_update_measurements(dev);
-	if (ret < 0)
-		return ret;
-	return sprintf(buf, "%d\n", htu21->humidity);
-}
-
-static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO,
-			  htu21_show_temperature, NULL, 0);
-static SENSOR_DEVICE_ATTR(humidity1_input, S_IRUGO,
-			  htu21_show_humidity, NULL, 0);
-
-static struct attribute *htu21_attrs[] = {
-	&sensor_dev_attr_temp1_input.dev_attr.attr,
-	&sensor_dev_attr_humidity1_input.dev_attr.attr,
-	NULL
-};
-
-ATTRIBUTE_GROUPS(htu21);
-
-static int htu21_probe(struct i2c_client *client,
-		       const struct i2c_device_id *id)
-{
-	struct device *dev = &client->dev;
-	struct htu21 *htu21;
-	struct device *hwmon_dev;
-
-	if (!i2c_check_functionality(client->adapter,
-				     I2C_FUNC_SMBUS_READ_WORD_DATA)) {
-		dev_err(&client->dev,
-			"adapter does not support SMBus word transactions\n");
-		return -ENODEV;
-	}
-
-	htu21 = devm_kzalloc(dev, sizeof(*htu21), GFP_KERNEL);
-	if (!htu21)
-		return -ENOMEM;
-
-	htu21->client = client;
-	mutex_init(&htu21->lock);
-
-	hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
-							   htu21,
-							   htu21_groups);
-	return PTR_ERR_OR_ZERO(hwmon_dev);
-}
-
-static const struct i2c_device_id htu21_id[] = {
-	{ "htu21", 0 },
-	{ }
-};
-MODULE_DEVICE_TABLE(i2c, htu21_id);
-
-static struct i2c_driver htu21_driver = {
-	.class = I2C_CLASS_HWMON,
-	.driver = {
-		.name	= "htu21",
-	},
-	.probe       = htu21_probe,
-	.id_table    = htu21_id,
-};
-
-module_i2c_driver(htu21_driver);
-
-MODULE_AUTHOR("William Markezana <william.markezana@meas-spec.com>");
-MODULE_DESCRIPTION("MEAS HTU21D humidity and temperature sensor driver");
-MODULE_LICENSE("GPL");