iio: accel: Add driver for the mCube MC3230 3-axis accelerometer

Add an IIO driver for the mCube MC3230 3-axis accelerometer.

A datasheet for the mCube MC3230 can be found here:
http://www.mcubemems.com/wp-content/uploads/2014/10/MC3230_2-Datasheet-APS-048-0007v1.6.pdf

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

Documentation/devicetree/bindings/i2c/trivial-devices.txt

@@ -57,6 +57,7 @@ maxim,ds1050		5 Bit Programmable, Pulse-Width Modulator
 maxim,max1237		Low-Power, 4-/12-Channel, 2-Wire Serial, 12-Bit ADCs
 maxim,max6625		9-Bit/12-Bit Temperature Sensors with I²C-Compatible Serial Interface
 mc,rv3029c2		Real Time Clock Module with I2C-Bus
+mcube,mc3230		mCube 3-axis 8-bit digital accelerometer
 microchip,mcp4531-502	Microchip 7-bit Single I2C Digital Potentiometer (5k)
 microchip,mcp4531-103	Microchip 7-bit Single I2C Digital Potentiometer (10k)
 microchip,mcp4531-503	Microchip 7-bit Single I2C Digital Potentiometer (50k)

drivers/iio/accel/Kconfig

@@ -161,6 +161,16 @@ config KXCJK1013
 	  To compile this driver as a module, choose M here: the module will
 	  be called kxcjk-1013.
 
+config MC3230
+	tristate "mCube MC3230 Digital Accelerometer Driver"
+	depends on I2C
+	help
+	  Say yes here to build support for the mCube MC3230 low-g tri-axial
+	  digital accelerometer.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called mc3230.
+
 config MMA7455
 	tristate
 	select IIO_BUFFER

drivers/iio/accel/Makefile

@@ -15,6 +15,7 @@ obj-$(CONFIG_KXCJK1013) += kxcjk-1013.o
 obj-$(CONFIG_KXSD9)	+= kxsd9.o
 obj-$(CONFIG_KXSD9_SPI)	+= kxsd9-spi.o
 obj-$(CONFIG_KXSD9_I2C)	+= kxsd9-i2c.o
+obj-$(CONFIG_MC3230)	+= mc3230.o
 
 obj-$(CONFIG_MMA7455)		+= mma7455_core.o
 obj-$(CONFIG_MMA7455_I2C)	+= mma7455_i2c.o

drivers/iio/accel/mc3230.c

@@ -0,0 +1,211 @@
+/**
+ * mCube MC3230 3-Axis Accelerometer
+ *
+ * Copyright (c) 2016 Hans de Goede <hdegoede@redhat.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * IIO driver for mCube MC3230; 7-bit I2C address: 0x4c.
+ */
+
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+
+#define MC3230_REG_XOUT			0x00
+#define MC3230_REG_YOUT			0x01
+#define MC3230_REG_ZOUT			0x02
+
+#define MC3230_REG_MODE			0x07
+#define MC3230_MODE_OPCON_MASK		0x03
+#define MC3230_MODE_OPCON_WAKE		0x01
+#define MC3230_MODE_OPCON_STANDBY	0x03
+
+#define MC3230_REG_CHIP_ID		0x18
+#define MC3230_CHIP_ID			0x01
+
+#define MC3230_REG_PRODUCT_CODE		0x3b
+#define MC3230_PRODUCT_CODE		0x19
+
+/*
+ * The accelerometer has one measurement range:
+ *
+ * -1.5g - +1.5g (8-bit, signed)
+ *
+ * scale = (1.5 + 1.5) * 9.81 / (2^8 - 1)	= 0.115411765
+ */
+
+static const int mc3230_nscale = 115411765;
+
+#define MC3230_CHANNEL(reg, axis) {	\
+	.type = IIO_ACCEL,	\
+	.address = reg,	\
+	.modified = 1,	\
+	.channel2 = IIO_MOD_##axis,	\
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),	\
+	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
+}
+
+static const struct iio_chan_spec mc3230_channels[] = {
+	MC3230_CHANNEL(MC3230_REG_XOUT, X),
+	MC3230_CHANNEL(MC3230_REG_YOUT, Y),
+	MC3230_CHANNEL(MC3230_REG_ZOUT, Z),
+};
+
+struct mc3230_data {
+	struct i2c_client *client;
+};
+
+static int mc3230_set_opcon(struct mc3230_data *data, int opcon)
+{
+	int ret;
+	struct i2c_client *client = data->client;
+
+	ret = i2c_smbus_read_byte_data(client, MC3230_REG_MODE);
+	if (ret < 0) {
+		dev_err(&client->dev, "failed to read mode reg: %d\n", ret);
+		return ret;
+	}
+
+	ret &= ~MC3230_MODE_OPCON_MASK;
+	ret |= opcon;
+
+	ret = i2c_smbus_write_byte_data(client, MC3230_REG_MODE, ret);
+	if (ret < 0) {
+		dev_err(&client->dev, "failed to write mode reg: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int mc3230_read_raw(struct iio_dev *indio_dev,
+				struct iio_chan_spec const *chan,
+				int *val, int *val2, long mask)
+{
+	struct mc3230_data *data = iio_priv(indio_dev);
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		ret = i2c_smbus_read_byte_data(data->client, chan->address);
+		if (ret < 0)
+			return ret;
+		*val = sign_extend32(ret, 7);
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		*val = 0;
+		*val2 = mc3230_nscale;
+		return IIO_VAL_INT_PLUS_NANO;
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct iio_info mc3230_info = {
+	.driver_module	= THIS_MODULE,
+	.read_raw	= mc3230_read_raw,
+};
+
+static int mc3230_probe(struct i2c_client *client,
+			const struct i2c_device_id *id)
+{
+	int ret;
+	struct iio_dev *indio_dev;
+	struct mc3230_data *data;
+
+	/* First check chip-id and product-id */
+	ret = i2c_smbus_read_byte_data(client, MC3230_REG_CHIP_ID);
+	if (ret != MC3230_CHIP_ID)
+		return (ret < 0) ? ret : -ENODEV;
+
+	ret = i2c_smbus_read_byte_data(client, MC3230_REG_PRODUCT_CODE);
+	if (ret != MC3230_PRODUCT_CODE)
+		return (ret < 0) ? ret : -ENODEV;
+
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
+	if (!indio_dev) {
+		dev_err(&client->dev, "iio allocation failed!\n");
+		return -ENOMEM;
+	}
+
+	data = iio_priv(indio_dev);
+	data->client = client;
+	i2c_set_clientdata(client, indio_dev);
+
+	indio_dev->dev.parent = &client->dev;
+	indio_dev->info = &mc3230_info;
+	indio_dev->name = "mc3230";
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->channels = mc3230_channels;
+	indio_dev->num_channels = ARRAY_SIZE(mc3230_channels);
+
+	ret = mc3230_set_opcon(data, MC3230_MODE_OPCON_WAKE);
+	if (ret < 0)
+		return ret;
+
+	ret = iio_device_register(indio_dev);
+	if (ret < 0) {
+		dev_err(&client->dev, "device_register failed\n");
+		mc3230_set_opcon(data, MC3230_MODE_OPCON_STANDBY);
+	}
+
+	return ret;
+}
+
+static int mc3230_remove(struct i2c_client *client)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(client);
+
+	iio_device_unregister(indio_dev);
+
+	return mc3230_set_opcon(iio_priv(indio_dev), MC3230_MODE_OPCON_STANDBY);
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int mc3230_suspend(struct device *dev)
+{
+	struct mc3230_data *data;
+
+	data = iio_priv(i2c_get_clientdata(to_i2c_client(dev)));
+
+	return mc3230_set_opcon(data, MC3230_MODE_OPCON_STANDBY);
+}
+
+static int mc3230_resume(struct device *dev)
+{
+	struct mc3230_data *data;
+
+	data = iio_priv(i2c_get_clientdata(to_i2c_client(dev)));
+
+	return mc3230_set_opcon(data, MC3230_MODE_OPCON_WAKE);
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(mc3230_pm_ops, mc3230_suspend, mc3230_resume);
+
+static const struct i2c_device_id mc3230_i2c_id[] = {
+	{"mc3230", 0},
+	{}
+};
+MODULE_DEVICE_TABLE(i2c, mc3230_i2c_id);
+
+static struct i2c_driver mc3230_driver = {
+	.driver = {
+		.name = "mc3230",
+		.pm = &mc3230_pm_ops,
+	},
+	.probe		= mc3230_probe,
+	.remove		= mc3230_remove,
+	.id_table	= mc3230_i2c_id,
+};
+
+module_i2c_driver(mc3230_driver);
+
+MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
+MODULE_DESCRIPTION("mCube MC3230 3-Axis Accelerometer driver");
+MODULE_LICENSE("GPL v2");