iio: imu: Add support for the FXOS8700 IMU

FXOS8700CQ is a small, low-power, 3-axis linear accelerometer and 3-axis
magnetometer combined into a single package. The device features a
selectable I2C or point-to-point SPI serial interface with 14-bit
accelerometer and 16-bit magnetometer ADC resolution along with
smart-embedded functions.

FXOS8700CQ has dynamically selectable accelerationfull-scale ranges of
±2 g/±4 g/±8 g and a fixed magnetic measurement range of ±1200 μT.
Output data rates (ODR) from 1.563 Hz to 800 Hz are selectable by the user
for each sensor. Interleaved magnetic and acceleration data is available
at ODR rates of up to 400 Hz. FXOS8700CQ is available in a plastic QFN
package and it is guaranteed to operate over the extended temperature
range of –40 °C to +85 °C.

TODO: Trigger and IRQ configuration support

Datasheet:
  http://cache.freescale.com/files/sensors/doc/data_sheet/FXOS8700CQ.pdf

Signed-off-by: Robert Jones <rjones@gateworks.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/imu/Kconfig

@@ -40,6 +40,33 @@ config ADIS16480
 
 source "drivers/iio/imu/bmi160/Kconfig"
 
+config FXOS8700
+	tristate
+
+config FXOS8700_I2C
+	tristate "NXP FXOS8700 I2C driver"
+	depends on I2C
+	select FXOS8700
+	select REGMAP_I2C
+	help
+	  Say yes here to build support for the NXP FXOS8700 m+g combo
+	  sensor on I2C.
+
+	  This driver can also be built as a module. If so, the module will be
+	  called fxos8700_i2c.
+
+config FXOS8700_SPI
+	tristate "NXP FXOS8700 SPI driver"
+	depends on SPI
+	select FXOS8700
+	select REGMAP_SPI
+	help
+	  Say yes here to build support for the NXP FXOS8700 m+g combo
+	  sensor on SPI.
+
+	  This driver can also be built as a module. If so, the module will be
+	  called fxos8700_spi.
+
 config KMX61
 	tristate "Kionix KMX61 6-axis accelerometer and magnetometer"
 	depends on I2C

drivers/iio/imu/Makefile

@@ -14,6 +14,11 @@ adis_lib-$(CONFIG_IIO_ADIS_LIB_BUFFER) += adis_buffer.o
 obj-$(CONFIG_IIO_ADIS_LIB) += adis_lib.o
 
 obj-y += bmi160/
+
+obj-$(CONFIG_FXOS8700) += fxos8700_core.o
+obj-$(CONFIG_FXOS8700_I2C) += fxos8700_i2c.o
+obj-$(CONFIG_FXOS8700_SPI) += fxos8700_spi.o
+
 obj-y += inv_mpu6050/
 
 obj-$(CONFIG_KMX61) += kmx61.o

drivers/iio/imu/fxos8700.h

@@ -0,0 +1,10 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef FXOS8700_H_
+#define FXOS8700_H_
+
+extern const struct regmap_config fxos8700_regmap_config;
+
+int fxos8700_core_probe(struct device *dev, struct regmap *regmap,
+			const char *name, bool use_spi);
+
+#endif  /* FXOS8700_H_ */

drivers/iio/imu/fxos8700_i2c.c

@@ -0,0 +1,71 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * FXOS8700 - NXP IMU, I2C bits
+ *
+ * 7-bit I2C slave address determined by SA1 and SA0 logic level
+ * inputs represented in the following table:
+ *      SA1  |  SA0  |  Slave Address
+ *      0    |  0    |  0x1E
+ *      0    |  1    |  0x1D
+ *      1    |  0    |  0x1C
+ *      1    |  1    |  0x1F
+ */
+#include <linux/acpi.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/mod_devicetable.h>
+#include <linux/regmap.h>
+
+#include "fxos8700.h"
+
+static int fxos8700_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, &fxos8700_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 fxos8700_core_probe(&client->dev, regmap, name, false);
+}
+
+static const struct i2c_device_id fxos8700_i2c_id[] = {
+	{"fxos8700", 0},
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, fxos8700_i2c_id);
+
+static const struct acpi_device_id fxos8700_acpi_match[] = {
+	{"FXOS8700", 0},
+	{ }
+};
+MODULE_DEVICE_TABLE(acpi, fxos8700_acpi_match);
+
+static const struct of_device_id fxos8700_of_match[] = {
+	{ .compatible = "nxp,fxos8700" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, fxos8700_of_match);
+
+static struct i2c_driver fxos8700_i2c_driver = {
+	.driver = {
+		.name                   = "fxos8700_i2c",
+		.acpi_match_table       = ACPI_PTR(fxos8700_acpi_match),
+		.of_match_table         = fxos8700_of_match,
+	},
+	.probe          = fxos8700_i2c_probe,
+	.id_table       = fxos8700_i2c_id,
+};
+module_i2c_driver(fxos8700_i2c_driver);
+
+MODULE_AUTHOR("Robert Jones <rjones@gateworks.com>");
+MODULE_DESCRIPTION("FXOS8700 I2C driver");
+MODULE_LICENSE("GPL v2");

drivers/iio/imu/fxos8700_spi.c

@@ -0,0 +1,59 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * FXOS8700 - NXP IMU, SPI bits
+ */
+#include <linux/acpi.h>
+#include <linux/module.h>
+#include <linux/mod_devicetable.h>
+#include <linux/regmap.h>
+#include <linux/spi/spi.h>
+
+#include "fxos8700.h"
+
+static int fxos8700_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, &fxos8700_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 fxos8700_core_probe(&spi->dev, regmap, id->name, true);
+}
+
+static const struct spi_device_id fxos8700_spi_id[] = {
+	{"fxos8700", 0},
+	{ }
+};
+MODULE_DEVICE_TABLE(spi, fxos8700_spi_id);
+
+static const struct acpi_device_id fxos8700_acpi_match[] = {
+	{"FXOS8700", 0},
+	{ }
+};
+MODULE_DEVICE_TABLE(acpi, fxos8700_acpi_match);
+
+static const struct of_device_id fxos8700_of_match[] = {
+	{ .compatible = "nxp,fxos8700" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, fxos8700_of_match);
+
+static struct spi_driver fxos8700_spi_driver = {
+	.probe          = fxos8700_spi_probe,
+	.id_table       = fxos8700_spi_id,
+	.driver = {
+		.acpi_match_table       = ACPI_PTR(fxos8700_acpi_match),
+		.of_match_table         = fxos8700_of_match,
+		.name                   = "fxos8700_spi",
+	},
+};
+module_spi_driver(fxos8700_spi_driver);
+
+MODULE_AUTHOR("Robert Jones <rjones@gateworks.com>");
+MODULE_DESCRIPTION("FXOS8700 SPI driver");
+MODULE_LICENSE("GPL v2");