[RFC 1/3] iio: imu: bme680: Add initial support for Bosch BME680

[Himanshu Jha <himanshujha199640@gmail.com>]

Implement a minimal probe function to register the device to the kernel.
The probe does a simple power on reset and then checks for chip id.

Datasheet: https://ae-bst.resource.bosch.com/media/_tech/media/datasheets/BST-BME680-DS001-00.pdf

Cc: Daniel Baluta <daniel.baluta@gmail.com>
Signed-off-by: Himanshu Jha <himanshujha199640@gmail.com>
---
 drivers/iio/imu/Kconfig              |   1 +
 drivers/iio/imu/Makefile             |   1 +
 drivers/iio/imu/bme680/Kconfig       |  32 +++++++++++
 drivers/iio/imu/bme680/Makefile      |   6 +++
 drivers/iio/imu/bme680/bme680.h      |  11 ++++
 drivers/iio/imu/bme680/bme680_core.c | 101 +++++++++++++++++++++++++++++++++++
 drivers/iio/imu/bme680/bme680_i2c.c  |  56 +++++++++++++++++++
 drivers/iio/imu/bme680/bme680_spi.c  |  49 +++++++++++++++++
 8 files changed, 257 insertions(+)
 create mode 100644 drivers/iio/imu/bme680/Kconfig
 create mode 100644 drivers/iio/imu/bme680/Makefile
 create mode 100644 drivers/iio/imu/bme680/bme680.h
 create mode 100644 drivers/iio/imu/bme680/bme680_core.c
 create mode 100644 drivers/iio/imu/bme680/bme680_i2c.c
 create mode 100644 drivers/iio/imu/bme680/bme680_spi.c

diff --git a/drivers/iio/imu/Kconfig b/drivers/iio/imu/Kconfig
index 156630a..cb7d2c0 100644
--- a/drivers/iio/imu/Kconfig
+++ b/drivers/iio/imu/Kconfig
@@ -26,6 +26,7 @@ config ADIS16480
 	  ADIS16485, ADIS16488 inertial sensors.
 
 source "drivers/iio/imu/bmi160/Kconfig"
+source "drivers/iio/imu/bme680/Kconfig"
 
 config KMX61
 	tristate "Kionix KMX61 6-axis accelerometer and magnetometer"
diff --git a/drivers/iio/imu/Makefile b/drivers/iio/imu/Makefile
index 68629c68..6c8c937 100644
--- a/drivers/iio/imu/Makefile
+++ b/drivers/iio/imu/Makefile
@@ -15,6 +15,7 @@ adis_lib-$(CONFIG_IIO_ADIS_LIB_BUFFER) += adis_buffer.o
 obj-$(CONFIG_IIO_ADIS_LIB) += adis_lib.o
 
 obj-y += bmi160/
+obj-y += bme680/
 obj-y += inv_mpu6050/
 
 obj-$(CONFIG_KMX61) += kmx61.o
diff --git a/drivers/iio/imu/bme680/Kconfig b/drivers/iio/imu/bme680/Kconfig
new file mode 100644
index 0000000..71c392b
--- /dev/null
+++ b/drivers/iio/imu/bme680/Kconfig
@@ -0,0 +1,32 @@
+#
+# Bosch BME680 Driver
+#
+
+config BME680
+	tristate
+	select IIO_BUFFER
+
+config BME680_I2C
+	tristate "Bosch BME680 I2C Driver"
+	depends on I2C
+	select BME680
+	select REGMAP_I2C
+	help
+	  If you say yes here you get support for BME680 on I2C with
+	  temperature, pressure, humidity & gas sensing.
+
+	  This driver can also be built as a module. If so, the module will be
+	  called bme68_i2c.
+
+config BME680_SPI
+	tristate "Bosch BME680 SPI Driver"
+	depends on SPI
+	select BME680
+	select REGMAP_SPI
+	help
+	  If you say yes here you get support for BME680 on SPI with
+	  temperature, pressure, humidity & gas sensing.
+
+	  This driver can also be built as a module. If so, the module will be
+	  called bme68_spi.
+
diff --git a/drivers/iio/imu/bme680/Makefile b/drivers/iio/imu/bme680/Makefile
new file mode 100644
index 0000000..562a708
--- /dev/null
+++ b/drivers/iio/imu/bme680/Makefile
@@ -0,0 +1,6 @@
+#
+# Makefile for Bosch BME680
+#
+obj-$(CONFIG_BME680) += bme680_core.o
+obj-$(CONFIG_BME680_I2C) += bme680_i2c.o
+obj-$(CONFIG_BME680_SPI) += bme680_spi.o
diff --git a/drivers/iio/imu/bme680/bme680.h b/drivers/iio/imu/bme680/bme680.h
new file mode 100644
index 0000000..9ee0cf5
--- /dev/null
+++ b/drivers/iio/imu/bme680/bme680.h
@@ -0,0 +1,11 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef BME680_H_
+#define BME680_H_
+
+extern const struct regmap_config bme680_regmap_config;
+
+int bme680_core_probe(struct device *dev, struct regmap *regmap,
+		      const char *name, bool use_spi);
+void bme680_core_remove(struct device *dev);
+
+#endif  /* BME680_H_ */
diff --git a/drivers/iio/imu/bme680/bme680_core.c b/drivers/iio/imu/bme680/bme680_core.c
new file mode 100644
index 0000000..a6d013d
--- /dev/null
+++ b/drivers/iio/imu/bme680/bme680_core.c
@@ -0,0 +1,101 @@
+/*
+ * Bosch BME680 - Temperature, Pressure, Humidity & Gas Sensor
+ *
+ * IIO core driver - I2C & SPI bus support
+ */
+#include <linux/iio/iio.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+
+#define BME680_REG_CHIP_I2C_ID	0xD0
+#define BME680_REG_CHIP_SPI_ID	0x50
+#define BME680_CHIP_ID_VAL	0x61
+#define BME680_SOFT_RESET	0xE0
+#define BME680_CMD_SOFTRESET	0xB6
+
+struct bme680_data {
+	struct regmap *regmap;
+};
+
+const struct regmap_config bme680_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+};
+EXPORT_SYMBOL(bme680_regmap_config);
+
+static const struct iio_info bme680_info = {
+};
+
+static int bme680_chip_init(struct bme680_data *data, bool use_spi)
+{
+	struct device *dev = regmap_get_device(data->regmap);
+	unsigned int val;
+	int ret;
+
+	/* Power on Soft Reset */
+	ret = regmap_write(data->regmap, BME680_SOFT_RESET, BME680_CMD_SOFTRESET);
+	if (ret < 0)
+		return ret;
+
+	if (!use_spi) {
+		ret = regmap_read(data->regmap, BME680_REG_CHIP_I2C_ID, &val);
+	} else {
+		ret = regmap_read(data->regmap, BME680_REG_CHIP_SPI_ID, &val);
+	}
+
+	if (ret < 0) {
+		dev_err(dev, "Error reading chip ID\n");
+		return ret;
+	}
+
+	if (val != BME680_CHIP_ID_VAL) {
+		dev_err(dev, "Wrong chip ID, got %x expected %x\n",
+				val, BME680_CHIP_ID_VAL);
+		return -ENODEV;
+	}
+
+	return 0;
+}
+
+int bme680_core_probe(struct device *dev, struct regmap *regmap,
+		      const char *name, bool use_spi)
+{
+	struct iio_dev *indio_dev;
+	struct bme680_data *data;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	data = iio_priv(indio_dev);
+	dev_set_drvdata(dev, indio_dev);
+	data->regmap = regmap;
+
+	ret = bme680_chip_init(data, use_spi);
+	if (ret < 0)
+		return ret;
+
+	indio_dev->dev.parent = dev;
+	indio_dev->name = name;
+	indio_dev->info = &bme680_info;
+
+	ret = iio_device_register(indio_dev);
+	if (ret < 0)
+		return ret;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(bme680_core_probe);
+
+void bme680_core_remove(struct device *dev)
+{
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct bme680_data *data = iio_priv(indio_dev);
+
+	iio_device_unregister(indio_dev);
+}
+EXPORT_SYMBOL_GPL(bme680_core_remove);
+
+MODULE_AUTHOR("Himanshu Jha <himanshujha199640@gmail.com>");
+MODULE_DESCRIPTION("Bosch BME680 Driver");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/iio/imu/bme680/bme680_i2c.c b/drivers/iio/imu/bme680/bme680_i2c.c
new file mode 100644
index 0000000..1c8223e
--- /dev/null
+++ b/drivers/iio/imu/bme680/bme680_i2c.c
@@ -0,0 +1,56 @@
+/*
+ * 7-Bit I2C slave address is:
+ *	- 0x76 if SDO is pulled to GND
+ *	- 0x77 if SDO is pulled to VDDIO
+ */
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+
+#include "bme680.h"
+
+static int bme680_i2c_probe(struct i2c_client *client,
+			    const struct i2c_device_id *id)
+{
+	struct regmap *regmap;
+	const char *name = NULL;
+
+	regmap = devm_regmap_init_i2c(client, &bme680_regmap_config);
+	if (IS_ERR(regmap)) {
+		dev_err(&client->dev, "Failed to register i2c regmap %d\n",
+				(int)PTR_ERR(regmap));
+		return PTR_ERR(regmap);
+	}
+
+	if (id)
+		name = id->name;
+
+	return bme680_core_probe(&client->dev, regmap, name, false);
+}
+
+static int bme680_i2c_remove(struct i2c_client *client)
+{
+	bme680_core_remove(&client->dev);
+
+	return 0;
+}
+
+static const struct i2c_device_id bme680_i2c_id[] = {
+	{"bme680", 0},
+	{},
+};
+MODULE_DEVICE_TABLE(i2c, bme680_i2c_id);
+
+static struct i2c_driver bme680_i2c_driver = {
+	.driver = {
+		.name = "bme680_i2c",
+	},
+	.probe = bme680_i2c_probe,
+	.remove = bme680_i2c_remove,
+	.id_table = bme680_i2c_id,
+};
+module_i2c_driver(bme680_i2c_driver);
+
+MODULE_AUTHOR("Himanshu Jha <himanshujha199640@gmail.com>");
+MODULE_DESCRIPTION("BME680 I2C driver");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/iio/imu/bme680/bme680_spi.c b/drivers/iio/imu/bme680/bme680_spi.c
new file mode 100644
index 0000000..c135924
--- /dev/null
+++ b/drivers/iio/imu/bme680/bme680_spi.c
@@ -0,0 +1,49 @@
+/*
+ * BME680 - SPI Driver
+ */
+#include <linux/module.h>
+#include <linux/spi/spi.h>
+#include <linux/regmap.h>
+
+#include "bme680.h"
+
+static int bme680_spi_probe(struct spi_device *spi)
+{
+	struct regmap *regmap;
+	const struct spi_device_id *id = spi_get_device_id(spi);
+
+	regmap = devm_regmap_init_spi(spi, &bme680_regmap_config);
+	if (IS_ERR(regmap)) {
+		dev_err(&spi->dev, "Failed to register spi regmap %d\n",
+				(int)PTR_ERR(regmap));
+		return PTR_ERR(regmap);
+	}
+	return bme680_core_probe(&spi->dev, regmap, id->name, true);
+}
+
+static int bme680_spi_remove(struct spi_device *spi)
+{
+	bme680_core_remove(&spi->dev);
+
+	return 0;
+}
+
+static const struct spi_device_id bme680_spi_id[] = {
+	{"bme680", 0},
+	{}
+};
+MODULE_DEVICE_TABLE(spi, bme680_spi_id);
+
+static struct spi_driver bme680_spi_driver = {
+	.driver = {
+		.name = "bme680_spi",
+	},
+	.probe = bme680_spi_probe,
+	.remove = bme680_spi_remove,
+	.id_table = bme680_spi_id,
+};
+module_spi_driver(bme680_spi_driver);
+
+MODULE_AUTHOR("Himanshu Jha <himanshujha199640@gmail.com>");
+MODULE_DESCRIPTION("Bosch BME680 SPI driver");
+MODULE_LICENSE("GPL v2");
-- 
2.7.4