iio: adxl372: Add support for I2C communication

The adxl372 is designed to communicate in either SPI or I2C protocol. It
autodetects the format being used, requiring no configuration control to
select the format.

Signed-off-by: Stefan Popa <stefan.popa@analog.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

MAINTAINERS

@@ -549,6 +549,7 @@ W:	http://ez.analog.com/community/linux-device-drivers
 S:	Supported
 F:	drivers/iio/accel/adxl372.c
 F:	drivers/iio/accel/adxl372_spi.c
+F:	drivers/iio/accel/adxl372_i2c.c
 F:	Documentation/devicetree/bindings/iio/accel/adxl372.txt
 
 AF9013 MEDIA DRIVER

drivers/iio/accel/Kconfig

@@ -76,6 +76,17 @@ config ADXL372_SPI
 	  To compile this driver as a module, choose M here: the
 	  module will be called adxl372_spi.
 
+config ADXL372_I2C
+	tristate "Analog Devices ADXL372 3-Axis Accelerometer I2C Driver"
+	depends on I2C
+	select ADXL372
+	select REGMAP_I2C
+	help
+	  Say yes here to add support for the Analog Devices ADXL372 triaxial
+	  acceleration sensor.
+	  To compile this driver as a module, choose M here: the
+	  module will be called adxl372_i2c.
+
 config BMA180
 	tristate "Bosch BMA180/BMA250 3-Axis Accelerometer Driver"
 	depends on I2C

drivers/iio/accel/Makefile

@@ -10,6 +10,7 @@ obj-$(CONFIG_ADXL345) += adxl345_core.o
 obj-$(CONFIG_ADXL345_I2C) += adxl345_i2c.o
 obj-$(CONFIG_ADXL345_SPI) += adxl345_spi.o
 obj-$(CONFIG_ADXL372) += adxl372.o
+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

drivers/iio/accel/adxl372.c

@@ -26,7 +26,6 @@
 #define ADXL372_DEVID			0x00
 #define ADXL372_DEVID_MST		0x01
 #define ADXL372_PARTID			0x02
-#define ADXL372_REVID			0x03
 #define ADXL372_STATUS_1		0x04
 #define ADXL372_STATUS_2		0x05
 #define ADXL372_FIFO_ENTRIES_2		0x06

drivers/iio/accel/adxl372.h

@@ -8,6 +8,8 @@
 #ifndef _ADXL372_H_
 #define _ADXL372_H_
 
+#define ADXL372_REVID	0x03
+
 int adxl372_probe(struct device *dev, struct regmap *regmap,
 		  int irq, const char *name);
 bool adxl372_readable_noinc_reg(struct device *dev, unsigned int reg);

drivers/iio/accel/adxl372_i2c.c

@@ -0,0 +1,61 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * ADXL372 3-Axis Digital Accelerometer I2C driver
+ *
+ * Copyright 2018 Analog Devices Inc.
+ */
+
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+
+#include "adxl372.h"
+
+static const struct regmap_config adxl372_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.readable_noinc_reg = adxl372_readable_noinc_reg,
+};
+
+static int adxl372_i2c_probe(struct i2c_client *client,
+			     const struct i2c_device_id *id)
+{
+	struct regmap *regmap;
+	unsigned int regval;
+	int ret;
+
+	regmap = devm_regmap_init_i2c(client, &adxl372_regmap_config);
+	if (IS_ERR(regmap))
+		return PTR_ERR(regmap);
+
+	ret = regmap_read(regmap, ADXL372_REVID, &regval);
+	if (ret < 0)
+		return ret;
+
+	/* Starting with the 3rd revision an I2C chip bug was fixed */
+	if (regval < 3)
+		dev_warn(&client->dev,
+		"I2C might not work properly with other devices on the bus");
+
+	return adxl372_probe(&client->dev, regmap, client->irq, id->name);
+}
+
+static const struct i2c_device_id adxl372_i2c_id[] = {
+	{ "adxl372", 0 },
+	{}
+};
+MODULE_DEVICE_TABLE(i2c, adxl372_i2c_id);
+
+static struct i2c_driver adxl372_i2c_driver = {
+	.driver = {
+		.name = "adxl372_i2c",
+	},
+	.probe = adxl372_i2c_probe,
+	.id_table = adxl372_i2c_id,
+};
+
+module_i2c_driver(adxl372_i2c_driver);
+
+MODULE_AUTHOR("Stefan Popa <stefan.popa@analog.com>");
+MODULE_DESCRIPTION("Analog Devices ADXL372 3-axis accelerometer I2C driver");
+MODULE_LICENSE("GPL");