iio: accel: Add driver for the BMA400

Add a IIO driver for the Bosch BMA400 3-axes ultra-low power accelerometer.
The driver supports reading from the acceleration and temperature
registers. The driver also supports reading and configuring the output data
rate, oversampling ratio, and scale.

Signed-off-by: Dan Robertson <dan@dlrobertson.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

MAINTAINERS

@@ -3064,6 +3064,13 @@ S:	Supported
 F:	drivers/net/bonding/
 F:	include/uapi/linux/if_bonding.h
 
+BOSCH SENSORTEC BMA400 ACCELEROMETER IIO DRIVER
+M:	Dan Robertson <dan@dlrobertson.com>
+L:	linux-iio@vger.kernel.org
+S:	Maintained
+F:	drivers/iio/accel/bma400*
+F:	Documentation/devicetree/bindings/iio/accel/bosch,bma400.yaml
+
 BPF (Safe dynamic programs and tools)
 M:	Alexei Starovoitov <ast@kernel.org>
 M:	Daniel Borkmann <daniel@iogearbox.net>

drivers/iio/accel/Kconfig

@@ -112,6 +112,22 @@ config BMA220
 	  To compile this driver as a module, choose M here: the
 	  module will be called bma220_spi.
 
+config BMA400
+	tristate "Bosch BMA400 3-Axis Accelerometer Driver"
+	select REGMAP
+	select BMA400_I2C if I2C
+	help
+	  Say Y here if you want to build a driver for the Bosch BMA400
+	  triaxial acceleration sensor.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called bma400_core and you will also get
+	  bma400_i2c if I2C is enabled.
+
+config BMA400_I2C
+	tristate
+	depends on BMA400
+
 config BMC150_ACCEL
 	tristate "Bosch BMC150 Accelerometer Driver"
 	select IIO_BUFFER

drivers/iio/accel/Makefile

@@ -14,6 +14,8 @@ obj-$(CONFIG_ADXL372_I2C) += adxl372_i2c.o
 obj-$(CONFIG_ADXL372_SPI) += adxl372_spi.o
 obj-$(CONFIG_BMA180) += bma180.o
 obj-$(CONFIG_BMA220) += bma220_spi.o
+obj-$(CONFIG_BMA400) += bma400_core.o
+obj-$(CONFIG_BMA400_I2C) += bma400_i2c.o
 obj-$(CONFIG_BMC150_ACCEL) += bmc150-accel-core.o
 obj-$(CONFIG_BMC150_ACCEL_I2C) += bmc150-accel-i2c.o
 obj-$(CONFIG_BMC150_ACCEL_SPI) += bmc150-accel-spi.o

drivers/iio/accel/bma400.h

@@ -0,0 +1,95 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Register constants and other forward declarations needed by the bma400
+ * sources.
+ *
+ * Copyright 2019 Dan Robertson <dan@dlrobertson.com>
+ */
+
+#ifndef _BMA400_H_
+#define _BMA400_H_
+
+#include <linux/bits.h>
+#include <linux/regmap.h>
+
+/*
+ * Read-Only Registers
+ */
+
+/* Status and ID registers */
+#define BMA400_CHIP_ID_REG          0x00
+#define BMA400_ERR_REG              0x02
+#define BMA400_STATUS_REG           0x03
+
+/* Acceleration registers */
+#define BMA400_X_AXIS_LSB_REG       0x04
+#define BMA400_X_AXIS_MSB_REG       0x05
+#define BMA400_Y_AXIS_LSB_REG       0x06
+#define BMA400_Y_AXIS_MSB_REG       0x07
+#define BMA400_Z_AXIS_LSB_REG       0x08
+#define BMA400_Z_AXIS_MSB_REG       0x09
+
+/* Sensor time registers */
+#define BMA400_SENSOR_TIME0         0x0a
+#define BMA400_SENSOR_TIME1         0x0b
+#define BMA400_SENSOR_TIME2         0x0c
+
+/* Event and interrupt registers */
+#define BMA400_EVENT_REG            0x0d
+#define BMA400_INT_STAT0_REG        0x0e
+#define BMA400_INT_STAT1_REG        0x0f
+#define BMA400_INT_STAT2_REG        0x10
+
+/* Temperature register */
+#define BMA400_TEMP_DATA_REG        0x11
+
+/* FIFO length and data registers */
+#define BMA400_FIFO_LENGTH0_REG     0x12
+#define BMA400_FIFO_LENGTH1_REG     0x13
+#define BMA400_FIFO_DATA_REG        0x14
+
+/* Step count registers */
+#define BMA400_STEP_CNT0_REG        0x15
+#define BMA400_STEP_CNT1_REG        0x16
+#define BMA400_STEP_CNT3_REG        0x17
+#define BMA400_STEP_STAT_REG        0x18
+
+/*
+ * Read-write configuration registers
+ */
+#define BMA400_ACC_CONFIG0_REG      0x19
+#define BMA400_ACC_CONFIG1_REG      0x1a
+#define BMA400_ACC_CONFIG2_REG      0x1b
+#define BMA400_CMD_REG              0x7e
+
+/* Chip ID of BMA 400 devices found in the chip ID register. */
+#define BMA400_ID_REG_VAL           0x90
+
+#define BMA400_LP_OSR_SHIFT         5
+#define BMA400_NP_OSR_SHIFT         4
+#define BMA400_SCALE_SHIFT          6
+
+#define BMA400_TWO_BITS_MASK        GENMASK(1, 0)
+#define BMA400_LP_OSR_MASK          GENMASK(6, 5)
+#define BMA400_NP_OSR_MASK          GENMASK(5, 4)
+#define BMA400_ACC_ODR_MASK         GENMASK(3, 0)
+#define BMA400_ACC_SCALE_MASK       GENMASK(7, 6)
+
+#define BMA400_ACC_ODR_MIN_RAW      0x05
+#define BMA400_ACC_ODR_LP_RAW       0x06
+#define BMA400_ACC_ODR_MAX_RAW      0x0b
+
+#define BMA400_ACC_ODR_MAX_HZ       800
+#define BMA400_ACC_ODR_MIN_WHOLE_HZ 25
+#define BMA400_ACC_ODR_MIN_HZ       12
+
+#define BMA400_SCALE_MIN            38357
+#define BMA400_SCALE_MAX            306864
+
+extern const struct regmap_config bma400_regmap_config;
+
+int bma400_probe(struct device *dev, struct regmap *regmap, const char *name);
+
+int bma400_remove(struct device *dev);
+
+#endif

drivers/iio/accel/bma400_i2c.c

@@ -0,0 +1,61 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * I2C IIO driver for Bosch BMA400 triaxial acceleration sensor.
+ *
+ * Copyright 2019 Dan Robertson <dan@dlrobertson.com>
+ *
+ * I2C address is either 0x14 or 0x15 depending on SDO
+ */
+#include <linux/i2c.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+
+#include "bma400.h"
+
+static int bma400_i2c_probe(struct i2c_client *client,
+			    const struct i2c_device_id *id)
+{
+	struct regmap *regmap;
+
+	regmap = devm_regmap_init_i2c(client, &bma400_regmap_config);
+	if (IS_ERR(regmap)) {
+		dev_err(&client->dev, "failed to create regmap\n");
+		return PTR_ERR(regmap);
+	}
+
+	return bma400_probe(&client->dev, regmap, id->name);
+}
+
+static int bma400_i2c_remove(struct i2c_client *client)
+{
+	return bma400_remove(&client->dev);
+}
+
+static const struct i2c_device_id bma400_i2c_ids[] = {
+	{ "bma400", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, bma400_i2c_ids);
+
+static const struct of_device_id bma400_of_i2c_match[] = {
+	{ .compatible = "bosch,bma400" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, bma400_of_i2c_match);
+
+static struct i2c_driver bma400_i2c_driver = {
+	.driver = {
+		.name = "bma400",
+		.of_match_table = bma400_of_i2c_match,
+	},
+	.probe    = bma400_i2c_probe,
+	.remove   = bma400_i2c_remove,
+	.id_table = bma400_i2c_ids,
+};
+
+module_i2c_driver(bma400_i2c_driver);
+
+MODULE_AUTHOR("Dan Robertson <dan@dlrobertson.com>");
+MODULE_DESCRIPTION("Bosch BMA400 triaxial acceleration sensor (I2C)");
+MODULE_LICENSE("GPL");