iio: pressure: bmp280: add support for BMP180

This adds support for the BMP180 to the bmp280 iio driver.

The BMP180 has already been supported by misc/bmp085 driver but it
doesn't use iio framework.  This change adds the kconfig dependency
not to be selected both of them in order to avoid any issues.
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Acked-by: Vlad Dogaru <vlad.dogaru@intel.com>
Cc: Christoph Mair <christoph.mair@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/pressure/Kconfig

@@ -6,12 +6,13 @@
 menu "Pressure sensors"
 
 config BMP280
-	tristate "Bosch Sensortec BMP280 pressure sensor driver"
+	tristate "Bosch Sensortec BMP180 and BMP280 pressure sensor driver"
 	depends on I2C
+	depends on !(BMP085_I2C=y || BMP085_I2C=m)
 	select REGMAP_I2C
 	help
-	  Say yes here to build support for Bosch Sensortec BMP280
-	  pressure and temperature sensor.
+	  Say yes here to build support for Bosch Sensortec BMP180 and BMP280
+	  pressure and temperature sensors.
 
 	  To compile this driver as a module, choose M here: the module
 	  will be called bmp280.

drivers/iio/pressure/bmp280.c

 /*
  * Copyright (c) 2014 Intel Corporation
  *
- * Driver for Bosch Sensortec BMP280 digital pressure sensor.
+ * 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
  */
 
 #define pr_fmt(fmt) "bmp280: " fmt
@@ -15,9 +18,11 @@
 #include <linux/i2c.h>
 #include <linux/acpi.h>
 #include <linux/regmap.h>
+#include <linux/delay.h>
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
 
+/* BMP280 specific registers */
 #define BMP280_REG_TEMP_XLSB		0xFC
 #define BMP280_REG_TEMP_LSB		0xFB
 #define BMP280_REG_TEMP_MSB		0xFA
@@ -26,10 +31,7 @@
 #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_RESET		0xE0
-#define BMP280_REG_ID			0xD0
 
 #define BMP280_REG_COMP_TEMP_START	0x88
 #define BMP280_COMP_TEMP_REG_COUNT	6
@@ -65,6 +67,28 @@
 #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 BMP280_SOFT_RESET_VAL		0xB6
 
@@ -72,6 +96,7 @@ struct bmp280_data {
 	struct i2c_client *client;
 	struct mutex lock;
 	struct regmap *regmap;
+	const struct bmp280_chip_info *chip_info;
 
 	/*
 	 * Carryover value from temperature conversion, used in pressure
@@ -80,9 +105,17 @@ struct bmp280_data {
 	s32 t_fine;
 };
 
+struct bmp280_chip_info {
+	const struct regmap_config *regmap_config;
+
+	int (*chip_config)(struct bmp280_data *);
+	int (*read_temp)(struct bmp280_data *, int *);
+	int (*read_press)(struct bmp280_data *, int *, int *);
+};
+
 /*
  * These enums are used for indexing into the array of compensation
- * parameters.
+ * parameters for BMP280.
  */
 enum { T1, T2, T3 };
 enum { P1, P2, P3, P4, P5, P6, P7, P8, P9 };
@@ -290,10 +323,10 @@ static int bmp280_read_raw(struct iio_dev *indio_dev,
 	case IIO_CHAN_INFO_PROCESSED:
 		switch (chan->type) {
 		case IIO_PRESSURE:
-			ret = bmp280_read_press(data, val, val2);
+			ret = data->chip_info->read_press(data, val, val2);
 			break;
 		case IIO_TEMP:
-			ret = bmp280_read_temp(data, val);
+			ret = data->chip_info->read_temp(data, val);
 			break;
 		default:
 			ret = -EINVAL;
@@ -315,7 +348,7 @@ static const struct iio_info bmp280_info = {
 	.read_raw = &bmp280_read_raw,
 };
 
-static int bmp280_chip_init(struct bmp280_data *data)
+static int bmp280_chip_config(struct bmp280_data *data)
 {
 	int ret;
 
@@ -344,6 +377,296 @@ static int bmp280_chip_init(struct bmp280_data *data)
 	return ret;
 }
 
+static const struct bmp280_chip_info bmp280_chip_info = {
+	.regmap_config = &bmp280_regmap_config,
+	.chip_config = bmp280_chip_config,
+	.read_temp = bmp280_read_temp,
+	.read_press = bmp280_read_press,
+};
+
+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;
+	}
+}
+
+static 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,
+};
+
+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;
+
+	ret = regmap_write(data->regmap, BMP280_REG_CTRL_MEAS, ctrl_meas);
+	if (ret)
+		return ret;
+
+	if (ctrl_meas == BMP180_MEAS_TEMP)
+		delay_us = 4500;
+	else
+		delay_us = conversion_time_max[ilog2(8)];
+
+	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;
+}
+
+/*
+ * 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;
+};
+
+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;
+	}
+
+	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)
+{
+	int ret;
+	s32 x1, x2;
+	struct bmp180_calib calib;
+
+	ret = bmp180_read_calib(data, &calib);
+	if (ret < 0) {
+		dev_err(&data->client->dev,
+			"failed to read calibration coefficients\n");
+		return ret;
+	}
+
+	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 = ilog2(8);
+
+	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)
+{
+	int ret;
+	s32 x1, x2, x3, p;
+	s32 b3, b6;
+	u32 b4, b7;
+	s32 oss = ilog2(8);
+	struct bmp180_calib calib;
+
+	ret = bmp180_read_calib(data, &calib);
+	if (ret < 0) {
+		dev_err(&data->client->dev,
+			"failed to read calibration coefficients\n");
+		return ret;
+	}
+
+	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 struct bmp280_chip_info bmp180_chip_info = {
+	.regmap_config = &bmp180_regmap_config,
+	.chip_config = bmp180_chip_config,
+	.read_temp = bmp180_read_temp,
+	.read_press = bmp180_read_press,
+};
+
 static int bmp280_probe(struct i2c_client *client,
 			const struct i2c_device_id *id)
 {
@@ -367,7 +690,19 @@ static int bmp280_probe(struct i2c_client *client,
 	indio_dev->info = &bmp280_info;
 	indio_dev->modes = INDIO_DIRECT_MODE;
 
-	data->regmap = devm_regmap_init_i2c(client, &bmp280_regmap_config);
+	switch (id->driver_data) {
+	case BMP180_CHIP_ID:
+		data->chip_info = &bmp180_chip_info;
+		break;
+	case BMP280_CHIP_ID:
+		data->chip_info = &bmp280_chip_info;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	data->regmap = devm_regmap_init_i2c(client,
+					data->chip_info->regmap_config);
 	if (IS_ERR(data->regmap)) {
 		dev_err(&client->dev, "failed to allocate register map\n");
 		return PTR_ERR(data->regmap);
@@ -376,13 +711,13 @@ static int bmp280_probe(struct i2c_client *client,
 	ret = regmap_read(data->regmap, BMP280_REG_ID, &chip_id);
 	if (ret < 0)
 		return ret;
-	if (chip_id != BMP280_CHIP_ID) {
+	if (chip_id != id->driver_data) {
 		dev_err(&client->dev, "bad chip id.  expected %x got %x\n",
 			BMP280_CHIP_ID, chip_id);
 		return -EINVAL;
 	}
 
-	ret = bmp280_chip_init(data);
+	ret = data->chip_info->chip_config(data);
 	if (ret < 0)
 		return ret;
 
@@ -390,13 +725,17 @@ static int bmp280_probe(struct i2c_client *client,
 }
 
 static const struct acpi_device_id bmp280_acpi_match[] = {
-	{"BMP0280", 0},
+	{"BMP0280", BMP280_CHIP_ID },
+	{"BMP0180", BMP180_CHIP_ID },
+	{"BMP0085", BMP180_CHIP_ID },
 	{ },
 };
 MODULE_DEVICE_TABLE(acpi, bmp280_acpi_match);
 
 static const struct i2c_device_id bmp280_id[] = {
-	{"bmp280", 0},
+	{"bmp280", BMP280_CHIP_ID },
+	{"bmp180", BMP180_CHIP_ID },
+	{"bmp085", BMP180_CHIP_ID },
 	{ },
 };
 MODULE_DEVICE_TABLE(i2c, bmp280_id);
@@ -412,5 +751,5 @@ static struct i2c_driver bmp280_driver = {
 module_i2c_driver(bmp280_driver);
 
 MODULE_AUTHOR("Vlad Dogaru <vlad.dogaru@intel.com>");
-MODULE_DESCRIPTION("Driver for Bosch Sensortec BMP280 pressure and temperature sensor");
+MODULE_DESCRIPTION("Driver for Bosch Sensortec BMP180/BMP280 pressure and temperature sensor");
 MODULE_LICENSE("GPL v2");