import of bmp280 code from mainline kernel

linux_kernel_modules/bmp280/Kconfig

+#
+# Pressure drivers
+#
+# When adding new entries keep the list in alphabetical order
+
+menu "BMP 280 Pressure sensor"
+
+config BMP280
+	tristate "Bosch Sensortec BMP180/BMP280 pressure sensor I2C driver"
+	depends on (I2C || SPI_MASTER)
+	select REGMAP
+	select BMP280_I2C if (I2C)
+	select BMP280_SPI if (SPI_MASTER)
+	help
+	  Say yes here to build support for Bosch Sensortec BMP180 and BMP280
+	  pressure and temperature sensors. Also supports the BE280 with
+	  an additional humidity sensor channel.
+
+	  To compile this driver as a module, choose M here: the core module
+	  will be called bmp280 and you will also get bmp280-i2c for I2C
+	  and/or bmp280-spi for SPI support.
+
+config BMP280_I2C
+	tristate
+	depends on BMP280
+	depends on I2C
+	select REGMAP_I2C
+
+config BMP280_SPI
+	tristate
+	depends on BMP280
+	depends on SPI_MASTER
+	select REGMAP
+
+endmenu

linux_kernel_modules/bmp280/Makefile

+#
+# Makefile for industrial I/O pressure drivers
+#
+
+# When adding new entries keep the list in alphabetical order
+obj-$(CONFIG_BMP280) += bmp280.o
+bmp280-objs := bmp280-core.o bmp280-regmap.o
+obj-$(CONFIG_BMP280_I2C) += bmp280-i2c.o
+obj-$(CONFIG_BMP280_SPI) += bmp280-spi.o

linux_kernel_modules/bmp280/README.md

+BMP280 Linux Kernel Driver
+==========================
+
+This version of the BMP280 Linux kernel driver has been extracted from the mainline kernel at
+revision e6925852d5b862bac749fab9c8d26491cda99e4e.  The files were taken from `drivers/iio/pressure`.

linux_kernel_modules/bmp280/bmp280-core.c

+/*
+ * Copyright (c) 2010 Christoph Mair <christoph.mair@gmail.com>
+ * Copyright (c) 2012 Bosch Sensortec GmbH
+ * Copyright (c) 2012 Unixphere AB
+ * Copyright (c) 2014 Intel Corporation
+ * Copyright (c) 2016 Linus Walleij <linus.walleij@linaro.org>
+ *
+ * Driver for Bosch Sensortec BMP180 and BMP280 digital pressure sensor.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * Datasheet:
+ * https://ae-bst.resource.bosch.com/media/_tech/media/datasheets/BST-BMP180-DS000-121.pdf
+ * https://ae-bst.resource.bosch.com/media/_tech/media/datasheets/BST-BMP280-DS001-12.pdf
+ * https://ae-bst.resource.bosch.com/media/_tech/media/datasheets/BST-BME280_DS001-11.pdf
+ */
+
+#define pr_fmt(fmt) "bmp280: " fmt
+
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <linux/delay.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/gpio/consumer.h>
+#include <linux/regulator/consumer.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h> /* For irq_get_irq_data() */
+#include <linux/completion.h>
+#include <linux/pm_runtime.h>
+#include <linux/random.h>
+
+#include "bmp280.h"
+
+/*
+ * These enums are used for indexing into the array of calibration
+ * coefficients for BMP180.
+ */
+enum { AC1, AC2, AC3, AC4, AC5, AC6, B1, B2, MB, MC, MD };
+
+struct bmp180_calib {
+	s16 AC1;
+	s16 AC2;
+	s16 AC3;
+	u16 AC4;
+	u16 AC5;
+	u16 AC6;
+	s16 B1;
+	s16 B2;
+	s16 MB;
+	s16 MC;
+	s16 MD;
+};
+
+struct bmp280_data {
+	struct device *dev;
+	struct mutex lock;
+	struct regmap *regmap;
+	struct completion done;
+	bool use_eoc;
+	const struct bmp280_chip_info *chip_info;
+	struct bmp180_calib calib;
+	struct regulator *vddd;
+	struct regulator *vdda;
+	unsigned int start_up_time; /* in milliseconds */
+
+	/* log of base 2 of oversampling rate */
+	u8 oversampling_press;
+	u8 oversampling_temp;
+	u8 oversampling_humid;
+
+	/*
+	 * Carryover value from temperature conversion, used in pressure
+	 * calculation.
+	 */
+	s32 t_fine;
+};
+
+struct bmp280_chip_info {
+	const int *oversampling_temp_avail;
+	int num_oversampling_temp_avail;
+
+	const int *oversampling_press_avail;
+	int num_oversampling_press_avail;
+
+	const int *oversampling_humid_avail;
+	int num_oversampling_humid_avail;
+
+	int (*chip_config)(struct bmp280_data *);
+	int (*read_temp)(struct bmp280_data *, int *);
+	int (*read_press)(struct bmp280_data *, int *, int *);
+	int (*read_humid)(struct bmp280_data *, int *, int *);
+};
+
+/*
+ * These enums are used for indexing into the array of compensation
+ * parameters for BMP280.
+ */
+enum { T1, T2, T3 };
+enum { P1, P2, P3, P4, P5, P6, P7, P8, P9 };
+
+static const struct iio_chan_spec bmp280_channels[] = {
+	{
+		.type = IIO_PRESSURE,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED) |
+				      BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
+	},
+	{
+		.type = IIO_TEMP,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED) |
+				      BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
+	},
+	{
+		.type = IIO_HUMIDITYRELATIVE,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED) |
+				      BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
+	},
+};
+
+/*
+ * Returns humidity in percent, resolution is 0.01 percent. Output value of
+ * "47445" represents 47445/1024 = 46.333 %RH.
+ *
+ * Taken from BME280 datasheet, Section 4.2.3, "Compensation formula".
+ */
+
+static u32 bmp280_compensate_humidity(struct bmp280_data *data,
+				      s32 adc_humidity)
+{
+	struct device *dev = data->dev;
+	unsigned int H1, H3, tmp;
+	int H2, H4, H5, H6, ret, var;
+
+	ret = regmap_read(data->regmap, BMP280_REG_COMP_H1, &H1);
+	if (ret < 0) {
+		dev_err(dev, "failed to read H1 comp value\n");
+		return ret;
+	}
+
+	ret = regmap_bulk_read(data->regmap, BMP280_REG_COMP_H2, &tmp, 2);
+	if (ret < 0) {
+		dev_err(dev, "failed to read H2 comp value\n");
+		return ret;
+	}
+	H2 = sign_extend32(le16_to_cpu(tmp), 15);
+
+	ret = regmap_read(data->regmap, BMP280_REG_COMP_H3, &H3);
+	if (ret < 0) {
+		dev_err(dev, "failed to read H3 comp value\n");
+		return ret;
+	}
+
+	ret = regmap_bulk_read(data->regmap, BMP280_REG_COMP_H4, &tmp, 2);
+	if (ret < 0) {
+		dev_err(dev, "failed to read H4 comp value\n");
+		return ret;
+	}
+	H4 = sign_extend32(((be16_to_cpu(tmp) >> 4) & 0xff0) |
+			  (be16_to_cpu(tmp) & 0xf), 11);
+
+	ret = regmap_bulk_read(data->regmap, BMP280_REG_COMP_H5, &tmp, 2);
+	if (ret < 0) {
+		dev_err(dev, "failed to read H5 comp value\n");
+		return ret;
+	}
+	H5 = sign_extend32(((le16_to_cpu(tmp) >> 4) & 0xfff), 11);
+
+	ret = regmap_read(data->regmap, BMP280_REG_COMP_H6, &tmp);
+	if (ret < 0) {
+		dev_err(dev, "failed to read H6 comp value\n");
+		return ret;
+	}
+	H6 = sign_extend32(tmp, 7);
+
+	var = ((s32)data->t_fine) - 76800;
+	var = ((((adc_humidity << 14) - (H4 << 20) - (H5 * var)) + 16384) >> 15)
+		* (((((((var * H6) >> 10) * (((var * H3) >> 11) + 32768)) >> 10)
+		+ 2097152) * H2 + 8192) >> 14);
+	var -= ((((var >> 15) * (var >> 15)) >> 7) * H1) >> 4;
+
+	return var >> 12;
+};
+
+/*
+ * Returns temperature in DegC, resolution is 0.01 DegC.  Output value of
+ * "5123" equals 51.23 DegC.  t_fine carries fine temperature as global
+ * value.
+ *
+ * Taken from datasheet, Section 3.11.3, "Compensation formula".
+ */
+static s32 bmp280_compensate_temp(struct bmp280_data *data,
+				  s32 adc_temp)
+{
+	int ret;
+	s32 var1, var2;
+	__le16 buf[BMP280_COMP_TEMP_REG_COUNT / 2];
+
+	ret = regmap_bulk_read(data->regmap, BMP280_REG_COMP_TEMP_START,
+			       buf, BMP280_COMP_TEMP_REG_COUNT);
+	if (ret < 0) {
+		dev_err(data->dev,
+			"failed to read temperature calibration parameters\n");
+		return ret;
+	}
+
+	/*
+	 * The double casts are necessary because le16_to_cpu returns an
+	 * unsigned 16-bit value.  Casting that value directly to a
+	 * signed 32-bit will not do proper sign extension.
+	 *
+	 * Conversely, T1 and P1 are unsigned values, so they can be
+	 * cast straight to the larger type.
+	 */
+	var1 = (((adc_temp >> 3) - ((s32)le16_to_cpu(buf[T1]) << 1)) *
+		((s32)(s16)le16_to_cpu(buf[T2]))) >> 11;
+	var2 = (((((adc_temp >> 4) - ((s32)le16_to_cpu(buf[T1]))) *
+		  ((adc_temp >> 4) - ((s32)le16_to_cpu(buf[T1])))) >> 12) *
+		((s32)(s16)le16_to_cpu(buf[T3]))) >> 14;
+	data->t_fine = var1 + var2;
+
+	return (data->t_fine * 5 + 128) >> 8;
+}
+
+/*
+ * Returns pressure in Pa as unsigned 32 bit integer in Q24.8 format (24
+ * integer bits and 8 fractional bits).  Output value of "24674867"
+ * represents 24674867/256 = 96386.2 Pa = 963.862 hPa
+ *
+ * Taken from datasheet, Section 3.11.3, "Compensation formula".
+ */
+static u32 bmp280_compensate_press(struct bmp280_data *data,
+				   s32 adc_press)
+{
+	int ret;
+	s64 var1, var2, p;
+	__le16 buf[BMP280_COMP_PRESS_REG_COUNT / 2];
+
+	ret = regmap_bulk_read(data->regmap, BMP280_REG_COMP_PRESS_START,
+			       buf, BMP280_COMP_PRESS_REG_COUNT);
+	if (ret < 0) {
+		dev_err(data->dev,
+			"failed to read pressure calibration parameters\n");
+		return ret;
+	}
+
+	var1 = ((s64)data->t_fine) - 128000;
+	var2 = var1 * var1 * (s64)(s16)le16_to_cpu(buf[P6]);
+	var2 += (var1 * (s64)(s16)le16_to_cpu(buf[P5])) << 17;
+	var2 += ((s64)(s16)le16_to_cpu(buf[P4])) << 35;
+	var1 = ((var1 * var1 * (s64)(s16)le16_to_cpu(buf[P3])) >> 8) +
+		((var1 * (s64)(s16)le16_to_cpu(buf[P2])) << 12);
+	var1 = ((((s64)1) << 47) + var1) * ((s64)le16_to_cpu(buf[P1])) >> 33;
+
+	if (var1 == 0)
+		return 0;
+
+	p = ((((s64)1048576 - adc_press) << 31) - var2) * 3125;
+	p = div64_s64(p, var1);
+	var1 = (((s64)(s16)le16_to_cpu(buf[P9])) * (p >> 13) * (p >> 13)) >> 25;
+	var2 = (((s64)(s16)le16_to_cpu(buf[P8])) * p) >> 19;
+	p = ((p + var1 + var2) >> 8) + (((s64)(s16)le16_to_cpu(buf[P7])) << 4);
+
+	return (u32)p;
+}
+
+static int bmp280_read_temp(struct bmp280_data *data,
+			    int *val)
+{
+	int ret;
+	__be32 tmp = 0;
+	s32 adc_temp, comp_temp;
+
+	ret = regmap_bulk_read(data->regmap, BMP280_REG_TEMP_MSB,
+			       (u8 *) &tmp, 3);
+	if (ret < 0) {
+		dev_err(data->dev, "failed to read temperature\n");
+		return ret;
+	}
+
+	adc_temp = be32_to_cpu(tmp) >> 12;
+	comp_temp = bmp280_compensate_temp(data, adc_temp);
+
+	/*
+	 * val might be NULL if we're called by the read_press routine,
+	 * who only cares about the carry over t_fine value.
+	 */
+	if (val) {
+		*val = comp_temp * 10;
+		return IIO_VAL_INT;
+	}
+
+	return 0;
+}
+
+static int bmp280_read_press(struct bmp280_data *data,
+			     int *val, int *val2)
+{
+	int ret;
+	__be32 tmp = 0;
+	s32 adc_press;
+	u32 comp_press;
+
+	/* Read and compensate temperature so we get a reading of t_fine. */
+	ret = bmp280_read_temp(data, NULL);
+	if (ret < 0)
+		return ret;
+
+	ret = regmap_bulk_read(data->regmap, BMP280_REG_PRESS_MSB,
+			       (u8 *) &tmp, 3);
+	if (ret < 0) {
+		dev_err(data->dev, "failed to read pressure\n");
+		return ret;
+	}
+
+	adc_press = be32_to_cpu(tmp) >> 12;
+	comp_press = bmp280_compensate_press(data, adc_press);
+
+	*val = comp_press;
+	*val2 = 256000;
+
+	return IIO_VAL_FRACTIONAL;
+}
+
+static int bmp280_read_humid(struct bmp280_data *data, int *val, int *val2)
+{
+	int ret;
+	__be16 tmp = 0;
+	s32 adc_humidity;
+	u32 comp_humidity;
+
+	/* Read and compensate temperature so we get a reading of t_fine. */
+	ret = bmp280_read_temp(data, NULL);
+	if (ret < 0)
+		return ret;
+
+	ret = regmap_bulk_read(data->regmap, BMP280_REG_HUMIDITY_MSB,
+			       (u8 *) &tmp, 2);
+	if (ret < 0) {
+		dev_err(data->dev, "failed to read humidity\n");
+		return ret;
+	}
+
+	adc_humidity = be16_to_cpu(tmp);
+	comp_humidity = bmp280_compensate_humidity(data, adc_humidity);
+
+	*val = comp_humidity;
+	*val2 = 1024;
+
+	return IIO_VAL_FRACTIONAL;
+}
+
+static int bmp280_read_raw(struct iio_dev *indio_dev,
+			   struct iio_chan_spec const *chan,
+			   int *val, int *val2, long mask)
+{
+	int ret;
+	struct bmp280_data *data = iio_priv(indio_dev);
+
+	pm_runtime_get_sync(data->dev);
+	mutex_lock(&data->lock);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_PROCESSED:
+		switch (chan->type) {
+		case IIO_HUMIDITYRELATIVE:
+			ret = data->chip_info->read_humid(data, val, val2);
+			break;
+		case IIO_PRESSURE:
+			ret = data->chip_info->read_press(data, val, val2);
+			break;
+		case IIO_TEMP:
+			ret = data->chip_info->read_temp(data, val);
+			break;
+		default:
+			ret = -EINVAL;
+			break;
+		}
+		break;
+	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+		switch (chan->type) {
+		case IIO_HUMIDITYRELATIVE:
+			*val = 1 << data->oversampling_humid;
+			ret = IIO_VAL_INT;
+			break;
+		case IIO_PRESSURE:
+			*val = 1 << data->oversampling_press;
+			ret = IIO_VAL_INT;
+			break;
+		case IIO_TEMP:
+			*val = 1 << data->oversampling_temp;
+			ret = IIO_VAL_INT;
+			break;
+		default:
+			ret = -EINVAL;
+			break;
+		}
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	}
+
+	mutex_unlock(&data->lock);
+	pm_runtime_mark_last_busy(data->dev);
+	pm_runtime_put_autosuspend(data->dev);
+
+	return ret;
+}
+
+static int bmp280_write_oversampling_ratio_humid(struct bmp280_data *data,
+					       int val)
+{
+	int i;
+	const int *avail = data->chip_info->oversampling_humid_avail;
+	const int n = data->chip_info->num_oversampling_humid_avail;
+
+	for (i = 0; i < n; i++) {
+		if (avail[i] == val) {
+			data->oversampling_humid = ilog2(val);
+
+			return data->chip_info->chip_config(data);
+		}
+	}
+	return -EINVAL;
+}
+
+static int bmp280_write_oversampling_ratio_temp(struct bmp280_data *data,
+					       int val)
+{
+	int i;
+	const int *avail = data->chip_info->oversampling_temp_avail;
+	const int n = data->chip_info->num_oversampling_temp_avail;
+
+	for (i = 0; i < n; i++) {
+		if (avail[i] == val) {
+			data->oversampling_temp = ilog2(val);
+
+			return data->chip_info->chip_config(data);
+		}
+	}
+	return -EINVAL;
+}
+
+static int bmp280_write_oversampling_ratio_press(struct bmp280_data *data,
+					       int val)
+{
+	int i;
+	const int *avail = data->chip_info->oversampling_press_avail;
+	const int n = data->chip_info->num_oversampling_press_avail;
+
+	for (i = 0; i < n; i++) {
+		if (avail[i] == val) {
+			data->oversampling_press = ilog2(val);
+
+			return data->chip_info->chip_config(data);
+		}
+	}
+	return -EINVAL;
+}
+
+static int bmp280_write_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan,
+			    int val, int val2, long mask)
+{
+	int ret = 0;
+	struct bmp280_data *data = iio_priv(indio_dev);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+		pm_runtime_get_sync(data->dev);
+		mutex_lock(&data->lock);
+		switch (chan->type) {
+		case IIO_HUMIDITYRELATIVE:
+			ret = bmp280_write_oversampling_ratio_humid(data, val);
+			break;
+		case IIO_PRESSURE:
+			ret = bmp280_write_oversampling_ratio_press(data, val);
+			break;
+		case IIO_TEMP:
+			ret = bmp280_write_oversampling_ratio_temp(data, val);
+			break;
+		default:
+			ret = -EINVAL;
+			break;
+		}
+		mutex_unlock(&data->lock);
+		pm_runtime_mark_last_busy(data->dev);
+		pm_runtime_put_autosuspend(data->dev);
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return ret;
+}
+
+static ssize_t bmp280_show_avail(char *buf, const int *vals, const int n)
+{
+	size_t len = 0;
+	int i;
+
+	for (i = 0; i < n; i++)
+		len += scnprintf(buf + len, PAGE_SIZE - len, "%d ", vals[i]);
+
+	buf[len - 1] = '\n';
+
+	return len;
+}
+
+static ssize_t bmp280_show_temp_oversampling_avail(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct bmp280_data *data = iio_priv(dev_to_iio_dev(dev));
+
+	return bmp280_show_avail(buf, data->chip_info->oversampling_temp_avail,
+				 data->chip_info->num_oversampling_temp_avail);
+}
+
+static ssize_t bmp280_show_press_oversampling_avail(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct bmp280_data *data = iio_priv(dev_to_iio_dev(dev));
+
+	return bmp280_show_avail(buf, data->chip_info->oversampling_press_avail,
+				 data->chip_info->num_oversampling_press_avail);
+}
+
+static IIO_DEVICE_ATTR(in_temp_oversampling_ratio_available,
+	S_IRUGO, bmp280_show_temp_oversampling_avail, NULL, 0);
+
+static IIO_DEVICE_ATTR(in_pressure_oversampling_ratio_available,
+	S_IRUGO, bmp280_show_press_oversampling_avail, NULL, 0);
+
+static struct attribute *bmp280_attributes[] = {
+	&iio_dev_attr_in_temp_oversampling_ratio_available.dev_attr.attr,
+	&iio_dev_attr_in_pressure_oversampling_ratio_available.dev_attr.attr,
+	NULL,
+};
+
+static const struct attribute_group bmp280_attrs_group = {
+	.attrs = bmp280_attributes,
+};
+
+static const struct iio_info bmp280_info = {
+	.driver_module = THIS_MODULE,
+	.read_raw = &bmp280_read_raw,
+	.write_raw = &bmp280_write_raw,
+	.attrs = &bmp280_attrs_group,
+};
+
+static int bmp280_chip_config(struct bmp280_data *data)
+{
+	int ret;
+	u8 osrs = BMP280_OSRS_TEMP_X(data->oversampling_temp + 1) |
+		  BMP280_OSRS_PRESS_X(data->oversampling_press + 1);
+
+	ret = regmap_update_bits(data->regmap, BMP280_REG_CTRL_MEAS,
+				 BMP280_OSRS_TEMP_MASK |
+				 BMP280_OSRS_PRESS_MASK |
+				 BMP280_MODE_MASK,
+				 osrs | BMP280_MODE_NORMAL);
+	if (ret < 0) {
+		dev_err(data->dev,
+			"failed to write ctrl_meas register\n");
+		return ret;
+	}
+
+	ret = regmap_update_bits(data->regmap, BMP280_REG_CONFIG,
+				 BMP280_FILTER_MASK,
+				 BMP280_FILTER_4X);
+	if (ret < 0) {
+		dev_err(data->dev,
+			"failed to write config register\n");
+		return ret;
+	}
+
+	return ret;
+}
+
+static const int bmp280_oversampling_avail[] = { 1, 2, 4, 8, 16 };
+
+static const struct bmp280_chip_info bmp280_chip_info = {
+	.oversampling_temp_avail = bmp280_oversampling_avail,
+	.num_oversampling_temp_avail = ARRAY_SIZE(bmp280_oversampling_avail),
+
+	.oversampling_press_avail = bmp280_oversampling_avail,
+	.num_oversampling_press_avail = ARRAY_SIZE(bmp280_oversampling_avail),
+
+	.chip_config = bmp280_chip_config,
+	.read_temp = bmp280_read_temp,
+	.read_press = bmp280_read_press,
+};
+
+static int bme280_chip_config(struct bmp280_data *data)
+{
+	int ret = bmp280_chip_config(data);
+	u8 osrs = BMP280_OSRS_HUMIDITIY_X(data->oversampling_humid + 1);
+
+	if (ret < 0)
+		return ret;
+
+	return regmap_update_bits(data->regmap, BMP280_REG_CTRL_HUMIDITY,
+				  BMP280_OSRS_HUMIDITY_MASK, osrs);
+}
+
+static const struct bmp280_chip_info bme280_chip_info = {
+	.oversampling_temp_avail = bmp280_oversampling_avail,
+	.num_oversampling_temp_avail = ARRAY_SIZE(bmp280_oversampling_avail),
+
+	.oversampling_press_avail = bmp280_oversampling_avail,
+	.num_oversampling_press_avail = ARRAY_SIZE(bmp280_oversampling_avail),
+
+	.oversampling_humid_avail = bmp280_oversampling_avail,
+	.num_oversampling_humid_avail = ARRAY_SIZE(bmp280_oversampling_avail),
+
+	.chip_config = bme280_chip_config,
+	.read_temp = bmp280_read_temp,
+	.read_press = bmp280_read_press,
+	.read_humid = bmp280_read_humid,
+};
+
+static int bmp180_measure(struct bmp280_data *data, u8 ctrl_meas)
+{
+	int ret;
+	const int conversion_time_max[] = { 4500, 7500, 13500, 25500 };
+	unsigned int delay_us;
+	unsigned int ctrl;
+
+	if (data->use_eoc)
+		init_completion(&data->done);
+
+	ret = regmap_write(data->regmap, BMP280_REG_CTRL_MEAS, ctrl_meas);
+	if (ret)
+		return ret;
+
+	if (data->use_eoc) {
+		/*
+		 * If we have a completion interrupt, use it, wait up to
+		 * 100ms. The longest conversion time listed is 76.5 ms for
+		 * advanced resolution mode.
+		 */
+		ret = wait_for_completion_timeout(&data->done,
+						  1 + msecs_to_jiffies(100));
+		if (!ret)
+			dev_err(data->dev, "timeout waiting for completion\n");
+	} else {
+		if (ctrl_meas == BMP180_MEAS_TEMP)
+			delay_us = 4500;
+		else
+			delay_us =
+				conversion_time_max[data->oversampling_press];
+
+		usleep_range(delay_us, delay_us + 1000);
+	}
+
+	ret = regmap_read(data->regmap, BMP280_REG_CTRL_MEAS, &ctrl);
+	if (ret)
+		return ret;
+
+	/* The value of this bit reset to "0" after conversion is complete */
+	if (ctrl & BMP180_MEAS_SCO)
+		return -EIO;
+
+	return 0;
+}
+
+static int bmp180_read_adc_temp(struct bmp280_data *data, int *val)
+{
+	int ret;
+	__be16 tmp = 0;
+
+	ret = bmp180_measure(data, BMP180_MEAS_TEMP);
+	if (ret)
+		return ret;
+
+	ret = regmap_bulk_read(data->regmap, BMP180_REG_OUT_MSB, (u8 *)&tmp, 2);
+	if (ret)
+		return ret;
+
+	*val = be16_to_cpu(tmp);
+
+	return 0;
+}
+
+static int bmp180_read_calib(struct bmp280_data *data,
+			     struct bmp180_calib *calib)
+{
+	int ret;
+	int i;
+	__be16 buf[BMP180_REG_CALIB_COUNT / 2];
+
+	ret = regmap_bulk_read(data->regmap, BMP180_REG_CALIB_START, buf,
+			       sizeof(buf));
+
+	if (ret < 0)
+		return ret;
+
+	/* None of the words has the value 0 or 0xFFFF */
+	for (i = 0; i < ARRAY_SIZE(buf); i++) {
+		if (buf[i] == cpu_to_be16(0) || buf[i] == cpu_to_be16(0xffff))
+			return -EIO;
+	}
+
+	/* Toss the calibration data into the entropy pool */
+	add_device_randomness(buf, sizeof(buf));
+
+	calib->AC1 = be16_to_cpu(buf[AC1]);
+	calib->AC2 = be16_to_cpu(buf[AC2]);
+	calib->AC3 = be16_to_cpu(buf[AC3]);
+	calib->AC4 = be16_to_cpu(buf[AC4]);
+	calib->AC5 = be16_to_cpu(buf[AC5]);
+	calib->AC6 = be16_to_cpu(buf[AC6]);
+	calib->B1 = be16_to_cpu(buf[B1]);
+	calib->B2 = be16_to_cpu(buf[B2]);
+	calib->MB = be16_to_cpu(buf[MB]);
+	calib->MC = be16_to_cpu(buf[MC]);
+	calib->MD = be16_to_cpu(buf[MD]);
+
+	return 0;
+}
+
+/*
+ * Returns temperature in DegC, resolution is 0.1 DegC.
+ * t_fine carries fine temperature as global value.
+ *
+ * Taken from datasheet, Section 3.5, "Calculating pressure and temperature".
+ */
+static s32 bmp180_compensate_temp(struct bmp280_data *data, s32 adc_temp)
+{
+	s32 x1, x2;
+	struct bmp180_calib *calib = &data->calib;
+
+	x1 = ((adc_temp - calib->AC6) * calib->AC5) >> 15;
+	x2 = (calib->MC << 11) / (x1 + calib->MD);
+	data->t_fine = x1 + x2;
+
+	return (data->t_fine + 8) >> 4;
+}
+
+static int bmp180_read_temp(struct bmp280_data *data, int *val)
+{
+	int ret;
+	s32 adc_temp, comp_temp;
+
+	ret = bmp180_read_adc_temp(data, &adc_temp);
+	if (ret)
+		return ret;
+
+	comp_temp = bmp180_compensate_temp(data, adc_temp);
+
+	/*
+	 * val might be NULL if we're called by the read_press routine,
+	 * who only cares about the carry over t_fine value.
+	 */
+	if (val) {
+		*val = comp_temp * 100;
+		return IIO_VAL_INT;
+	}
+
+	return 0;
+}
+
+static int bmp180_read_adc_press(struct bmp280_data *data, int *val)
+{
+	int ret;
+	__be32 tmp = 0;
+	u8 oss = data->oversampling_press;
+
+	ret = bmp180_measure(data, BMP180_MEAS_PRESS_X(oss));
+	if (ret)
+		return ret;
+
+	ret = regmap_bulk_read(data->regmap, BMP180_REG_OUT_MSB, (u8 *)&tmp, 3);
+	if (ret)
+		return ret;
+
+	*val = (be32_to_cpu(tmp) >> 8) >> (8 - oss);
+
+	return 0;
+}
+
+/*
+ * Returns pressure in Pa, resolution is 1 Pa.
+ *
+ * Taken from datasheet, Section 3.5, "Calculating pressure and temperature".
+ */
+static u32 bmp180_compensate_press(struct bmp280_data *data, s32 adc_press)
+{
+	s32 x1, x2, x3, p;
+	s32 b3, b6;
+	u32 b4, b7;
+	s32 oss = data->oversampling_press;
+	struct bmp180_calib *calib = &data->calib;
+
+	b6 = data->t_fine - 4000;
+	x1 = (calib->B2 * (b6 * b6 >> 12)) >> 11;
+	x2 = calib->AC2 * b6 >> 11;
+	x3 = x1 + x2;
+	b3 = ((((s32)calib->AC1 * 4 + x3) << oss) + 2) / 4;
+	x1 = calib->AC3 * b6 >> 13;
+	x2 = (calib->B1 * ((b6 * b6) >> 12)) >> 16;
+	x3 = (x1 + x2 + 2) >> 2;
+	b4 = calib->AC4 * (u32)(x3 + 32768) >> 15;
+	b7 = ((u32)adc_press - b3) * (50000 >> oss);
+	if (b7 < 0x80000000)
+		p = (b7 * 2) / b4;
+	else
+		p = (b7 / b4) * 2;
+
+	x1 = (p >> 8) * (p >> 8);
+	x1 = (x1 * 3038) >> 16;
+	x2 = (-7357 * p) >> 16;
+
+	return p + ((x1 + x2 + 3791) >> 4);
+}
+
+static int bmp180_read_press(struct bmp280_data *data,
+			     int *val, int *val2)
+{
+	int ret;
+	s32 adc_press;
+	u32 comp_press;
+
+	/* Read and compensate temperature so we get a reading of t_fine. */
+	ret = bmp180_read_temp(data, NULL);
+	if (ret)
+		return ret;
+
+	ret = bmp180_read_adc_press(data, &adc_press);
+	if (ret)
+		return ret;
+
+	comp_press = bmp180_compensate_press(data, adc_press);
+
+	*val = comp_press;
+	*val2 = 1000;
+
+	return IIO_VAL_FRACTIONAL;
+}
+
+static int bmp180_chip_config(struct bmp280_data *data)
+{
+	return 0;
+}
+
+static const int bmp180_oversampling_temp_avail[] = { 1 };
+static const int bmp180_oversampling_press_avail[] = { 1, 2, 4, 8 };
+
+static const struct bmp280_chip_info bmp180_chip_info = {
+	.oversampling_temp_avail = bmp180_oversampling_temp_avail,
+	.num_oversampling_temp_avail =
+		ARRAY_SIZE(bmp180_oversampling_temp_avail),
+
+	.oversampling_press_avail = bmp180_oversampling_press_avail,
+	.num_oversampling_press_avail =
+		ARRAY_SIZE(bmp180_oversampling_press_avail),
+
+	.chip_config = bmp180_chip_config,
+	.read_temp = bmp180_read_temp,
+	.read_press = bmp180_read_press,
+};
+
+static irqreturn_t bmp085_eoc_irq(int irq, void *d)
+{
+	struct bmp280_data *data = d;
+
+	complete(&data->done);
+
+	return IRQ_HANDLED;
+}
+
+static int bmp085_fetch_eoc_irq(struct device *dev,
+				const char *name,
+				int irq,
+				struct bmp280_data *data)
+{
+	unsigned long irq_trig;
+	int ret;
+
+	irq_trig = irqd_get_trigger_type(irq_get_irq_data(irq));
+	if (irq_trig != IRQF_TRIGGER_RISING) {
+		dev_err(dev, "non-rising trigger given for EOC interrupt, "
+			"trying to enforce it\n");
+		irq_trig = IRQF_TRIGGER_RISING;
+	}
+	ret = devm_request_threaded_irq(dev,
+			irq,
+			bmp085_eoc_irq,
+			NULL,
+			irq_trig,
+			name,
+			data);
+	if (ret) {
+		/* Bail out without IRQ but keep the driver in place */
+		dev_err(dev, "unable to request DRDY IRQ\n");
+		return 0;
+	}
+
+	data->use_eoc = true;
+	return 0;
+}
+
+int bmp280_common_probe(struct device *dev,
+			struct regmap *regmap,
+			unsigned int chip,
+			const char *name,
+			int irq)
+{
+	int ret;
+	struct iio_dev *indio_dev;
+	struct bmp280_data *data;
+	unsigned int chip_id;
+	struct gpio_desc *gpiod;
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	data = iio_priv(indio_dev);
+	mutex_init(&data->lock);
+	data->dev = dev;
+
+	indio_dev->dev.parent = dev;
+	indio_dev->name = name;
+	indio_dev->channels = bmp280_channels;
+	indio_dev->info = &bmp280_info;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+
+	switch (chip) {
+	case BMP180_CHIP_ID:
+		indio_dev->num_channels = 2;
+		data->chip_info = &bmp180_chip_info;
+		data->oversampling_press = ilog2(8);
+		data->oversampling_temp = ilog2(1);
+		data->start_up_time = 10;
+		break;
+	case BMP280_CHIP_ID:
+		indio_dev->num_channels = 2;
+		data->chip_info = &bmp280_chip_info;
+		data->oversampling_press = ilog2(16);
+		data->oversampling_temp = ilog2(2);
+		data->start_up_time = 2;
+		break;
+	case BME280_CHIP_ID:
+		indio_dev->num_channels = 3;
+		data->chip_info = &bme280_chip_info;
+		data->oversampling_press = ilog2(16);
+		data->oversampling_humid = ilog2(16);
+		data->oversampling_temp = ilog2(2);
+		data->start_up_time = 2;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	/* Bring up regulators */
+	data->vddd = devm_regulator_get(dev, "vddd");
+	if (IS_ERR(data->vddd)) {
+		dev_err(dev, "failed to get VDDD regulator\n");
+		return PTR_ERR(data->vddd);
+	}
+	ret = regulator_enable(data->vddd);
+	if (ret) {
+		dev_err(dev, "failed to enable VDDD regulator\n");
+		return ret;
+	}
+	data->vdda = devm_regulator_get(dev, "vdda");
+	if (IS_ERR(data->vdda)) {
+		dev_err(dev, "failed to get VDDA regulator\n");
+		ret = PTR_ERR(data->vdda);
+		goto out_disable_vddd;
+	}
+	ret = regulator_enable(data->vdda);
+	if (ret) {
+		dev_err(dev, "failed to enable VDDA regulator\n");
+		goto out_disable_vddd;
+	}
+	/* Wait to make sure we started up properly */
+	mdelay(data->start_up_time);
+
+	/* Bring chip out of reset if there is an assigned GPIO line */
+	gpiod = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
+	/* Deassert the signal */
+	if (!IS_ERR(gpiod)) {
+		dev_info(dev, "release reset\n");
+		gpiod_set_value(gpiod, 0);
+	}
+
+	data->regmap = regmap;
+	ret = regmap_read(regmap, BMP280_REG_ID, &chip_id);
+	if (ret < 0)
+		goto out_disable_vdda;
+	if (chip_id != chip) {
+		dev_err(dev, "bad chip id: expected %x got %x\n",
+			chip, chip_id);
+		ret = -EINVAL;
+		goto out_disable_vdda;
+	}
+
+	ret = data->chip_info->chip_config(data);
+	if (ret < 0)
+		goto out_disable_vdda;
+
+	dev_set_drvdata(dev, indio_dev);
+
+	/*
+	 * The BMP085 and BMP180 has calibration in an E2PROM, read it out
+	 * at probe time. It will not change.
+	 */
+	if (chip_id  == BMP180_CHIP_ID) {
+		ret = bmp180_read_calib(data, &data->calib);
+		if (ret < 0) {
+			dev_err(data->dev,
+				"failed to read calibration coefficients\n");
+			goto out_disable_vdda;
+		}
+	}
+
+	/*
+	 * Attempt to grab an optional EOC IRQ - only the BMP085 has this
+	 * however as it happens, the BMP085 shares the chip ID of BMP180
+	 * so we look for an IRQ if we have that.
+	 */
+	if (irq > 0 || (chip_id  == BMP180_CHIP_ID)) {
+		ret = bmp085_fetch_eoc_irq(dev, name, irq, data);
+		if (ret)
+			goto out_disable_vdda;
+	}
+
+	/* Enable runtime PM */
+	pm_runtime_get_noresume(dev);
+	pm_runtime_set_active(dev);
+	pm_runtime_enable(dev);
+	/*
+	 * Set autosuspend to two orders of magnitude larger than the
+	 * start-up time.
+	 */
+	pm_runtime_set_autosuspend_delay(dev, data->start_up_time *100);
+	pm_runtime_use_autosuspend(dev);
+	pm_runtime_put(dev);
+
+	ret = iio_device_register(indio_dev);
+	if (ret)
+		goto out_runtime_pm_disable;
+
+
+	return 0;
+
+out_runtime_pm_disable:
+	pm_runtime_get_sync(data->dev);
+	pm_runtime_put_noidle(data->dev);
+	pm_runtime_disable(data->dev);
+out_disable_vdda:
+	regulator_disable(data->vdda);
+out_disable_vddd:
+	regulator_disable(data->vddd);
+	return ret;
+}
+EXPORT_SYMBOL(bmp280_common_probe);
+
+int bmp280_common_remove(struct device *dev)
+{
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct bmp280_data *data = iio_priv(indio_dev);
+
+	iio_device_unregister(indio_dev);
+	pm_runtime_get_sync(data->dev);
+	pm_runtime_put_noidle(data->dev);
+	pm_runtime_disable(data->dev);
+	regulator_disable(data->vdda);
+	regulator_disable(data->vddd);
+	return 0;
+}
+EXPORT_SYMBOL(bmp280_common_remove);
+
+#ifdef CONFIG_PM
+static int bmp280_runtime_suspend(struct device *dev)
+{
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct bmp280_data *data = iio_priv(indio_dev);
+	int ret;
+
+	ret = regulator_disable(data->vdda);
+	if (ret)
+		return ret;
+	return regulator_disable(data->vddd);
+}
+
+static int bmp280_runtime_resume(struct device *dev)
+{
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct bmp280_data *data = iio_priv(indio_dev);
+	int ret;
+
+	ret = regulator_enable(data->vddd);
+	if (ret)
+		return ret;
+	ret = regulator_enable(data->vdda);
+	if (ret)
+		return ret;
+	msleep(data->start_up_time);
+	return data->chip_info->chip_config(data);
+}
+#endif /* CONFIG_PM */
+
+const struct dev_pm_ops bmp280_dev_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
+				pm_runtime_force_resume)
+	SET_RUNTIME_PM_OPS(bmp280_runtime_suspend,
+			   bmp280_runtime_resume, NULL)
+};
+EXPORT_SYMBOL(bmp280_dev_pm_ops);
+
+MODULE_AUTHOR("Vlad Dogaru <vlad.dogaru@intel.com>");
+MODULE_DESCRIPTION("Driver for Bosch Sensortec BMP180/BMP280 pressure and temperature sensor");
+MODULE_LICENSE("GPL v2");

linux_kernel_modules/bmp280/bmp280-i2c.c

+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/acpi.h>
+#include <linux/of.h>
+#include <linux/regmap.h>
+
+#include "bmp280.h"
+
+static int bmp280_i2c_probe(struct i2c_client *client,
+			    const struct i2c_device_id *id)
+{
+	struct regmap *regmap;
+	const struct regmap_config *regmap_config;
+
+	switch (id->driver_data) {
+	case BMP180_CHIP_ID:
+		regmap_config = &bmp180_regmap_config;
+		break;
+	case BMP280_CHIP_ID:
+	case BME280_CHIP_ID:
+		regmap_config = &bmp280_regmap_config;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	regmap = devm_regmap_init_i2c(client, regmap_config);
+	if (IS_ERR(regmap)) {
+		dev_err(&client->dev, "failed to allocate register map\n");
+		return PTR_ERR(regmap);
+	}
+
+	return bmp280_common_probe(&client->dev,
+				   regmap,
+				   id->driver_data,
+				   id->name,
+				   client->irq);
+}
+
+static int bmp280_i2c_remove(struct i2c_client *client)
+{
+	return bmp280_common_remove(&client->dev);
+}
+
+static const struct acpi_device_id bmp280_acpi_i2c_match[] = {
+	{"BMP0280", BMP280_CHIP_ID },
+	{"BMP0180", BMP180_CHIP_ID },
+	{"BMP0085", BMP180_CHIP_ID },
+	{"BME0280", BME280_CHIP_ID },
+	{ },
+};
+MODULE_DEVICE_TABLE(acpi, bmp280_acpi_i2c_match);
+
+#ifdef CONFIG_OF
+static const struct of_device_id bmp280_of_i2c_match[] = {
+	{ .compatible = "bosch,bme280", .data = (void *)BME280_CHIP_ID },
+	{ .compatible = "bosch,bmp280", .data = (void *)BMP280_CHIP_ID },
+	{ .compatible = "bosch,bmp180", .data = (void *)BMP180_CHIP_ID },
+	{ .compatible = "bosch,bmp085", .data = (void *)BMP180_CHIP_ID },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, bmp280_of_i2c_match);
+#else
+#define bmp280_of_i2c_match NULL
+#endif
+
+static const struct i2c_device_id bmp280_i2c_id[] = {
+	{"bmp280", BMP280_CHIP_ID },
+	{"bmp180", BMP180_CHIP_ID },
+	{"bmp085", BMP180_CHIP_ID },
+	{"bme280", BME280_CHIP_ID },
+	{ },
+};
+MODULE_DEVICE_TABLE(i2c, bmp280_i2c_id);
+
+static struct i2c_driver bmp280_i2c_driver = {
+	.driver = {
+		.name	= "bmp280",
+		.acpi_match_table = ACPI_PTR(bmp280_acpi_i2c_match),
+		.of_match_table = of_match_ptr(bmp280_of_i2c_match),
+		.pm = &bmp280_dev_pm_ops,
+	},
+	.probe		= bmp280_i2c_probe,
+	.remove		= bmp280_i2c_remove,
+	.id_table	= bmp280_i2c_id,
+};
+module_i2c_driver(bmp280_i2c_driver);
+
+MODULE_AUTHOR("Vlad Dogaru <vlad.dogaru@intel.com>");
+MODULE_DESCRIPTION("Driver for Bosch Sensortec BMP180/BMP280 pressure and temperature sensor");
+MODULE_LICENSE("GPL v2");

linux_kernel_modules/bmp280/bmp280-regmap.c

+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+
+#include "bmp280.h"
+
+static bool bmp180_is_writeable_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case BMP280_REG_CTRL_MEAS:
+	case BMP280_REG_RESET:
+		return true;
+	default:
+		return false;
+	};
+}
+
+static bool bmp180_is_volatile_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case BMP180_REG_OUT_XLSB:
+	case BMP180_REG_OUT_LSB:
+	case BMP180_REG_OUT_MSB:
+	case BMP280_REG_CTRL_MEAS:
+		return true;
+	default:
+		return false;
+	}
+}
+
+const struct regmap_config bmp180_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+
+	.max_register = BMP180_REG_OUT_XLSB,
+	.cache_type = REGCACHE_RBTREE,
+
+	.writeable_reg = bmp180_is_writeable_reg,
+	.volatile_reg = bmp180_is_volatile_reg,
+};
+EXPORT_SYMBOL(bmp180_regmap_config);
+
+static bool bmp280_is_writeable_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case BMP280_REG_CONFIG:
+	case BMP280_REG_CTRL_HUMIDITY:
+	case BMP280_REG_CTRL_MEAS:
+	case BMP280_REG_RESET:
+		return true;
+	default:
+		return false;
+	};
+}
+
+static bool bmp280_is_volatile_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case BMP280_REG_HUMIDITY_LSB:
+	case BMP280_REG_HUMIDITY_MSB:
+	case BMP280_REG_TEMP_XLSB:
+	case BMP280_REG_TEMP_LSB:
+	case BMP280_REG_TEMP_MSB:
+	case BMP280_REG_PRESS_XLSB:
+	case BMP280_REG_PRESS_LSB:
+	case BMP280_REG_PRESS_MSB:
+	case BMP280_REG_STATUS:
+		return true;
+	default:
+		return false;
+	}
+}
+
+const struct regmap_config bmp280_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+
+	.max_register = BMP280_REG_HUMIDITY_LSB,
+	.cache_type = REGCACHE_RBTREE,
+
+	.writeable_reg = bmp280_is_writeable_reg,
+	.volatile_reg = bmp280_is_volatile_reg,
+};
+EXPORT_SYMBOL(bmp280_regmap_config);

linux_kernel_modules/bmp280/bmp280-spi.c

+/*
+ * SPI interface for the BMP280 driver
+ *
+ * Inspired by the older BMP085 driver drivers/misc/bmp085-spi.c
+ */
+#include <linux/module.h>
+#include <linux/spi/spi.h>
+#include <linux/err.h>
+#include <linux/regmap.h>
+
+#include "bmp280.h"
+
+static int bmp280_regmap_spi_write(void *context, const void *data,
+                                   size_t count)
+{
+	struct device *dev = context;
+	struct spi_device *spi = to_spi_device(dev);
+	u8 buf[2];
+
+	memcpy(buf, data, 2);
+	/*
+	 * The SPI register address (= full register address without bit 7) and
+	 * the write command (bit7 = RW = '0')
+	 */
+	buf[0] &= ~0x80;
+
+	return spi_write_then_read(spi, buf, 2, NULL, 0);
+}
+
+static int bmp280_regmap_spi_read(void *context, const void *reg,
+                                  size_t reg_size, void *val, size_t val_size)
+{
+	struct device *dev = context;
+	struct spi_device *spi = to_spi_device(dev);
+
+	return spi_write_then_read(spi, reg, reg_size, val, val_size);
+}
+
+static struct regmap_bus bmp280_regmap_bus = {
+	.write = bmp280_regmap_spi_write,
+	.read = bmp280_regmap_spi_read,
+	.reg_format_endian_default = REGMAP_ENDIAN_BIG,
+	.val_format_endian_default = REGMAP_ENDIAN_BIG,
+};
+
+static int bmp280_spi_probe(struct spi_device *spi)
+{
+	const struct spi_device_id *id = spi_get_device_id(spi);
+	struct regmap *regmap;
+	const struct regmap_config *regmap_config;
+	int ret;
+
+	spi->bits_per_word = 8;
+	ret = spi_setup(spi);
+	if (ret < 0) {
+		dev_err(&spi->dev, "spi_setup failed!\n");
+		return ret;
+	}
+
+	switch (id->driver_data) {
+	case BMP180_CHIP_ID:
+		regmap_config = &bmp180_regmap_config;
+		break;
+	case BMP280_CHIP_ID:
+	case BME280_CHIP_ID:
+		regmap_config = &bmp280_regmap_config;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	regmap = devm_regmap_init(&spi->dev,
+				  &bmp280_regmap_bus,
+				  &spi->dev,
+				  regmap_config);
+	if (IS_ERR(regmap)) {
+		dev_err(&spi->dev, "failed to allocate register map\n");
+		return PTR_ERR(regmap);
+	}
+
+	return bmp280_common_probe(&spi->dev,
+				   regmap,
+				   id->driver_data,
+				   id->name,
+				   spi->irq);
+}
+
+static int bmp280_spi_remove(struct spi_device *spi)
+{
+	return bmp280_common_remove(&spi->dev);
+}
+
+static const struct of_device_id bmp280_of_spi_match[] = {
+	{ .compatible = "bosch,bmp085", },
+	{ .compatible = "bosch,bmp180", },
+	{ .compatible = "bosch,bmp181", },
+	{ .compatible = "bosch,bmp280", },
+	{ .compatible = "bosch,bme280", },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, bmp280_of_spi_match);
+
+static const struct spi_device_id bmp280_spi_id[] = {
+	{ "bmp180", BMP180_CHIP_ID },
+	{ "bmp181", BMP180_CHIP_ID },
+	{ "bmp280", BMP280_CHIP_ID },
+	{ "bme280", BME280_CHIP_ID },
+	{ }
+};
+MODULE_DEVICE_TABLE(spi, bmp280_spi_id);
+
+static struct spi_driver bmp280_spi_driver = {
+	.driver = {
+		.name = "bmp280",
+		.of_match_table = bmp280_of_spi_match,
+		.pm = &bmp280_dev_pm_ops,
+	},
+	.id_table = bmp280_spi_id,
+	.probe = bmp280_spi_probe,
+	.remove = bmp280_spi_remove,
+};
+module_spi_driver(bmp280_spi_driver);
+
+MODULE_DESCRIPTION("BMP280 SPI bus driver");
+MODULE_LICENSE("GPL");

linux_kernel_modules/bmp280/bmp280.h

+#include <linux/bitops.h>
+#include <linux/device.h>
+#include <linux/regmap.h>
+
+/* BMP280 specific registers */
+#define BMP280_REG_HUMIDITY_LSB		0xFE
+#define BMP280_REG_HUMIDITY_MSB		0xFD
+#define BMP280_REG_TEMP_XLSB		0xFC
+#define BMP280_REG_TEMP_LSB		0xFB
+#define BMP280_REG_TEMP_MSB		0xFA
+#define BMP280_REG_PRESS_XLSB		0xF9
+#define BMP280_REG_PRESS_LSB		0xF8
+#define BMP280_REG_PRESS_MSB		0xF7
+
+#define BMP280_REG_CONFIG		0xF5
+#define BMP280_REG_CTRL_MEAS		0xF4
+#define BMP280_REG_STATUS		0xF3
+#define BMP280_REG_CTRL_HUMIDITY	0xF2
+
+/* Due to non linear mapping, and data sizes we can't do a bulk read */
+#define BMP280_REG_COMP_H1		0xA1
+#define BMP280_REG_COMP_H2		0xE1
+#define BMP280_REG_COMP_H3		0xE3
+#define BMP280_REG_COMP_H4		0xE4
+#define BMP280_REG_COMP_H5		0xE5
+#define BMP280_REG_COMP_H6		0xE7
+
+#define BMP280_REG_COMP_TEMP_START	0x88
+#define BMP280_COMP_TEMP_REG_COUNT	6
+
+#define BMP280_REG_COMP_PRESS_START	0x8E
+#define BMP280_COMP_PRESS_REG_COUNT	18
+
+#define BMP280_FILTER_MASK		(BIT(4) | BIT(3) | BIT(2))
+#define BMP280_FILTER_OFF		0
+#define BMP280_FILTER_2X		BIT(2)
+#define BMP280_FILTER_4X		BIT(3)
+#define BMP280_FILTER_8X		(BIT(3) | BIT(2))
+#define BMP280_FILTER_16X		BIT(4)
+
+#define BMP280_OSRS_HUMIDITY_MASK	(BIT(2) | BIT(1) | BIT(0))
+#define BMP280_OSRS_HUMIDITIY_X(osrs_h)	((osrs_h) << 0)
+#define BMP280_OSRS_HUMIDITY_SKIP	0
+#define BMP280_OSRS_HUMIDITY_1X		BMP280_OSRS_HUMIDITIY_X(1)
+#define BMP280_OSRS_HUMIDITY_2X		BMP280_OSRS_HUMIDITIY_X(2)
+#define BMP280_OSRS_HUMIDITY_4X		BMP280_OSRS_HUMIDITIY_X(3)
+#define BMP280_OSRS_HUMIDITY_8X		BMP280_OSRS_HUMIDITIY_X(4)
+#define BMP280_OSRS_HUMIDITY_16X	BMP280_OSRS_HUMIDITIY_X(5)
+
+#define BMP280_OSRS_TEMP_MASK		(BIT(7) | BIT(6) | BIT(5))
+#define BMP280_OSRS_TEMP_SKIP		0
+#define BMP280_OSRS_TEMP_X(osrs_t)	((osrs_t) << 5)
+#define BMP280_OSRS_TEMP_1X		BMP280_OSRS_TEMP_X(1)
+#define BMP280_OSRS_TEMP_2X		BMP280_OSRS_TEMP_X(2)
+#define BMP280_OSRS_TEMP_4X		BMP280_OSRS_TEMP_X(3)
+#define BMP280_OSRS_TEMP_8X		BMP280_OSRS_TEMP_X(4)
+#define BMP280_OSRS_TEMP_16X		BMP280_OSRS_TEMP_X(5)
+
+#define BMP280_OSRS_PRESS_MASK		(BIT(4) | BIT(3) | BIT(2))
+#define BMP280_OSRS_PRESS_SKIP		0
+#define BMP280_OSRS_PRESS_X(osrs_p)	((osrs_p) << 2)
+#define BMP280_OSRS_PRESS_1X		BMP280_OSRS_PRESS_X(1)
+#define BMP280_OSRS_PRESS_2X		BMP280_OSRS_PRESS_X(2)
+#define BMP280_OSRS_PRESS_4X		BMP280_OSRS_PRESS_X(3)
+#define BMP280_OSRS_PRESS_8X		BMP280_OSRS_PRESS_X(4)
+#define BMP280_OSRS_PRESS_16X		BMP280_OSRS_PRESS_X(5)
+
+#define BMP280_MODE_MASK		(BIT(1) | BIT(0))
+#define BMP280_MODE_SLEEP		0
+#define BMP280_MODE_FORCED		BIT(0)
+#define BMP280_MODE_NORMAL		(BIT(1) | BIT(0))
+
+/* BMP180 specific registers */
+#define BMP180_REG_OUT_XLSB		0xF8
+#define BMP180_REG_OUT_LSB		0xF7
+#define BMP180_REG_OUT_MSB		0xF6
+
+#define BMP180_REG_CALIB_START		0xAA
+#define BMP180_REG_CALIB_COUNT		22
+
+#define BMP180_MEAS_SCO			BIT(5)
+#define BMP180_MEAS_TEMP		(0x0E | BMP180_MEAS_SCO)
+#define BMP180_MEAS_PRESS_X(oss)	((oss) << 6 | 0x14 | BMP180_MEAS_SCO)
+#define BMP180_MEAS_PRESS_1X		BMP180_MEAS_PRESS_X(0)
+#define BMP180_MEAS_PRESS_2X		BMP180_MEAS_PRESS_X(1)
+#define BMP180_MEAS_PRESS_4X		BMP180_MEAS_PRESS_X(2)
+#define BMP180_MEAS_PRESS_8X		BMP180_MEAS_PRESS_X(3)
+
+/* BMP180 and BMP280 common registers */
+#define BMP280_REG_CTRL_MEAS		0xF4
+#define BMP280_REG_RESET		0xE0
+#define BMP280_REG_ID			0xD0
+
+#define BMP180_CHIP_ID			0x55
+#define BMP280_CHIP_ID			0x58
+#define BME280_CHIP_ID			0x60
+#define BMP280_SOFT_RESET_VAL		0xB6
+
+/* Regmap configurations */
+extern const struct regmap_config bmp180_regmap_config;
+extern const struct regmap_config bmp280_regmap_config;
+
+/* Probe called from different transports */
+int bmp280_common_probe(struct device *dev,
+			struct regmap *regmap,
+			unsigned int chip,
+			const char *name,
+			int irq);
+int bmp280_common_remove(struct device *dev);
+
+/* PM ops */
+extern const struct dev_pm_ops bmp280_dev_pm_ops;