iio: accel: Add driver for the MiraMEMS DA280 3-axis 14-bit digital accelerometer

Add an iio driver for the MiraMEMS DA280 3-axis 14-bit accelerometer, as
well as for the DA226 which is a fully compatible 2-axis version.

Datasheets for the DA280 and DA226 can be found at the manufacturers site:
http://www.miramems.com/en/products.asp?list=1

Signed-off-by: Hans de Goede <[e-mail]>
Acked-by: Rob Herring <[e-mail]>
Signed-off-by: Jonathan Cameron <[e-mail]>

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

···
 microchip,mcp4662-103	Microchip 8-bit Dual I2C Digital Potentiometer with NV Memory (10k)
 microchip,mcp4662-503	Microchip 8-bit Dual I2C Digital Potentiometer with NV Memory (50k)
 microchip,mcp4662-104	Microchip 8-bit Dual I2C Digital Potentiometer with NV Memory (100k)
+miramems,da226		MiraMEMS DA226 2-axis 14-bit digital accelerometer
+miramems,da280		MiraMEMS DA280 3-axis 14-bit digital accelerometer
 miramems,da311		MiraMEMS DA311 3-axis 12-bit digital accelerometer
 national,lm63		Temperature sensor with integrated fan control
 national,lm75		I2C TEMP SENSOR

drivers/iio/accel/Kconfig

···
 	tristate
 	select REGMAP_SPI
 
+config DA280
+	tristate "MiraMEMS DA280 3-axis 14-bit digital accelerometer driver"
+	depends on I2C
+	help
+	  Say yes here to build support for the MiraMEMS DA280 3-axis 14-bit
+	  digital accelerometer.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called da280.
+
 config DA311
 	tristate "MiraMEMS DA311 3-axis 12-bit digital accelerometer driver"
 	depends on I2C

drivers/iio/accel/Makefile

···
 obj-$(CONFIG_BMC150_ACCEL) += bmc150-accel-core.o
 obj-$(CONFIG_BMC150_ACCEL_I2C) += bmc150-accel-i2c.o
 obj-$(CONFIG_BMC150_ACCEL_SPI) += bmc150-accel-spi.o
+obj-$(CONFIG_DA280)	+= da280.o
 obj-$(CONFIG_DA311)	+= da311.o
 obj-$(CONFIG_DMARD06)	+= dmard06.o
 obj-$(CONFIG_DMARD09)	+= dmard09.o

drivers/iio/accel/da280.c

···
+/**
+ * IIO driver for the MiraMEMS DA280 3-axis accelerometer and
+ * IIO driver for the MiraMEMS DA226 2-axis accelerometer
+ *
+ * Copyright (c) 2016 Hans de Goede <[e-mail]>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ */
+
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/byteorder/generic.h>
+
+#define DA280_REG_CHIP_ID		0x01
+#define DA280_REG_ACC_X_LSB		0x02
+#define DA280_REG_ACC_Y_LSB		0x04
+#define DA280_REG_ACC_Z_LSB		0x06
+#define DA280_REG_MODE_BW		0x11
+
+#define DA280_CHIP_ID			0x13
+#define DA280_MODE_ENABLE		0x1e
+#define DA280_MODE_DISABLE		0x9e
+
+enum { da226, da280 };
+
+/*
+ * a value of + or -4096 corresponds to + or - 1G
+ * scale = 9.81 / 4096 = 0.002395019
+ */
+
+static const int da280_nscale = 2395019;
+
+#define DA280_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 da280_channels[] = {
+	DA280_CHANNEL(DA280_REG_ACC_X_LSB, X),
+	DA280_CHANNEL(DA280_REG_ACC_Y_LSB, Y),
+	DA280_CHANNEL(DA280_REG_ACC_Z_LSB, Z),
+};
+
+struct da280_data {
+	struct i2c_client *client;
+};
+
+static int da280_enable(struct i2c_client *client, bool enable)
+{
+	u8 data = enable ? DA280_MODE_ENABLE : DA280_MODE_DISABLE;
+
+	return i2c_smbus_write_byte_data(client, DA280_REG_MODE_BW, data);
+}
+
+static int da280_read_raw(struct iio_dev *indio_dev,
+				struct iio_chan_spec const *chan,
+				int *val, int *val2, long mask)
+{
+	struct da280_data *data = iio_priv(indio_dev);
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		ret = i2c_smbus_read_word_data(data->client, chan->address);
+		if (ret < 0)
+			return ret;
+		/*
+		 * Values are 14 bits, stored as 16 bits with the 2
+		 * least significant bits always 0.
+		 */
+		*val = (short)ret >> 2;
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		*val = 0;
+		*val2 = da280_nscale;
+		return IIO_VAL_INT_PLUS_NANO;
+	default:
+		return -EINVAL;
+	}
+}
+
+static const struct iio_info da280_info = {
+	.driver_module	= THIS_MODULE,
+	.read_raw	= da280_read_raw,
+};
+
+static int da280_probe(struct i2c_client *client,
+			const struct i2c_device_id *id)
+{
+	int ret;
+	struct iio_dev *indio_dev;
+	struct da280_data *data;
+
+	ret = i2c_smbus_read_byte_data(client, DA280_REG_CHIP_ID);
+	if (ret != DA280_CHIP_ID)
+		return (ret < 0) ? ret : -ENODEV;
+
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
+	if (!indio_dev)
+		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 = &da280_info;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->channels = da280_channels;
+	if (id->driver_data == da226) {
+		indio_dev->name = "da226";
+		indio_dev->num_channels = 2;
+	} else {
+		indio_dev->name = "da280";
+		indio_dev->num_channels = 3;
+	}
+
+	ret = da280_enable(client, true);
+	if (ret < 0)
+		return ret;
+
+	ret = iio_device_register(indio_dev);
+	if (ret < 0) {
+		dev_err(&client->dev, "device_register failed\n");
+		da280_enable(client, false);
+	}
+
+	return ret;
+}
+
+static int da280_remove(struct i2c_client *client)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(client);
+
+	iio_device_unregister(indio_dev);
+
+	return da280_enable(client, false);
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int da280_suspend(struct device *dev)
+{
+	return da280_enable(to_i2c_client(dev), false);
+}
+
+static int da280_resume(struct device *dev)
+{
+	return da280_enable(to_i2c_client(dev), true);
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(da280_pm_ops, da280_suspend, da280_resume);
+
+static const struct i2c_device_id da280_i2c_id[] = {
+	{ "da226", da226 },
+	{ "da280", da280 },
+	{}
+};
+MODULE_DEVICE_TABLE(i2c, da280_i2c_id);
+
+static struct i2c_driver da280_driver = {
+	.driver = {
+		.name = "da280",
+		.pm = &da280_pm_ops,
+	},
+	.probe		= da280_probe,
+	.remove		= da280_remove,
+	.id_table	= da280_i2c_id,
+};
+
+module_i2c_driver(da280_driver);
+
+MODULE_AUTHOR("Hans de Goede <[e-mail]>");
+MODULE_DESCRIPTION("MiraMEMS DA280 3-Axis Accelerometer driver");
+MODULE_LICENSE("GPL v2");