iio: accel: Add support for Freescale MMA7660FC

Minimal implementation of an IIO driver for the Freescale
MMA7660FC 3-axis accelerometer. Datasheet:
http://www.nxp.com/files/sensors/doc/data_sheet/MMA7660FC.pdf

Includes:
- ACPI support;
- read_raw for x,y,z axes;
- reading and setting the scale (range) parameter.
- power management
Signed-off-by: Constantin Musca <constantin.musca@intel.com>
Reviewed-by: Martin Klepplinger <martink@posteo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/accel/Kconfig

@@ -136,6 +136,16 @@ config MMA7455_SPI
 	  To compile this driver as a module, choose M here: the module
 	  will be called mma7455_spi.
 
+config MMA7660
+	tristate "Freescale MMA7660FC 3-Axis Accelerometer Driver"
+	depends on I2C
+	help
+	  Say yes here to get support for the Freescale MMA7660FC 3-Axis
+	  accelerometer.
+
+	  Choosing M will build the driver as a module. If so, the module
+	  will be called mma7660.
+
 config MMA8452
 	tristate "Freescale MMA8452Q and similar Accelerometers Driver"
 	depends on I2C

drivers/iio/accel/Makefile

@@ -15,6 +15,8 @@ obj-$(CONFIG_MMA7455)		+= mma7455_core.o
 obj-$(CONFIG_MMA7455_I2C)	+= mma7455_i2c.o
 obj-$(CONFIG_MMA7455_SPI)	+= mma7455_spi.o
 
+obj-$(CONFIG_MMA7660)	+= mma7660.o
+
 obj-$(CONFIG_MMA8452)	+= mma8452.o
 
 obj-$(CONFIG_MMA9551_CORE)	+= mma9551_core.o

drivers/iio/accel/mma7660.c

+/**
+ * Freescale MMA7660FC 3-Axis Accelerometer
+ *
+ * Copyright (c) 2016, Intel Corporation.
+ *
+ * This file is subject to the terms and conditions of version 2 of
+ * the GNU General Public License. See the file COPYING in the main
+ * directory of this archive for more details.
+ *
+ * IIO driver for Freescale MMA7660FC; 7-bit I2C address: 0x4c.
+ */
+
+#include <linux/acpi.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+
+#define MMA7660_DRIVER_NAME	"mma7660"
+
+#define MMA7660_REG_XOUT	0x00
+#define MMA7660_REG_YOUT	0x01
+#define MMA7660_REG_ZOUT	0x02
+#define MMA7660_REG_OUT_BIT_ALERT	BIT(6)
+
+#define MMA7660_REG_MODE	0x07
+#define MMA7660_REG_MODE_BIT_MODE	BIT(0)
+#define MMA7660_REG_MODE_BIT_TON	BIT(2)
+
+#define MMA7660_I2C_READ_RETRIES	5
+
+/*
+ * The accelerometer has one measurement range:
+ *
+ * -1.5g - +1.5g (6-bit, signed)
+ *
+ * scale = (1.5 + 1.5) * 9.81 / (2^6 - 1)	= 0.467142857
+ */
+
+#define MMA7660_SCALE_AVAIL	"0.467142857"
+
+const int mma7660_nscale = 467142857;
+
+#define MMA7660_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 mma7660_channels[] = {
+	MMA7660_CHANNEL(MMA7660_REG_XOUT, X),
+	MMA7660_CHANNEL(MMA7660_REG_YOUT, Y),
+	MMA7660_CHANNEL(MMA7660_REG_ZOUT, Z),
+};
+
+enum mma7660_mode {
+	MMA7660_MODE_STANDBY,
+	MMA7660_MODE_ACTIVE
+};
+
+struct mma7660_data {
+	struct i2c_client *client;
+	struct mutex lock;
+	enum mma7660_mode mode;
+};
+
+static IIO_CONST_ATTR(in_accel_scale_available, MMA7660_SCALE_AVAIL);
+
+static struct attribute *mma7660_attributes[] = {
+	&iio_const_attr_in_accel_scale_available.dev_attr.attr,
+	NULL,
+};
+
+static const struct attribute_group mma7660_attribute_group = {
+	.attrs = mma7660_attributes
+};
+
+static int mma7660_set_mode(struct mma7660_data *data,
+				enum mma7660_mode mode)
+{
+	int ret;
+	struct i2c_client *client = data->client;
+
+	if (mode == data->mode)
+		return 0;
+
+	ret = i2c_smbus_read_byte_data(client, MMA7660_REG_MODE);
+	if (ret < 0) {
+		dev_err(&client->dev, "failed to read sensor mode\n");
+		return ret;
+	}
+
+	if (mode == MMA7660_MODE_ACTIVE) {
+		ret &= ~MMA7660_REG_MODE_BIT_TON;
+		ret |= MMA7660_REG_MODE_BIT_MODE;
+	} else {
+		ret &= ~MMA7660_REG_MODE_BIT_TON;
+		ret &= ~MMA7660_REG_MODE_BIT_MODE;
+	}
+
+	ret = i2c_smbus_write_byte_data(client, MMA7660_REG_MODE, ret);
+	if (ret < 0) {
+		dev_err(&client->dev, "failed to change sensor mode\n");
+		return ret;
+	}
+
+	data->mode = mode;
+
+	return ret;
+}
+
+static int mma7660_read_accel(struct mma7660_data *data, u8 address)
+{
+	int ret, retries = MMA7660_I2C_READ_RETRIES;
+	struct i2c_client *client = data->client;
+
+	/*
+	 * Read data. If the Alert bit is set, the register was read at
+	 * the same time as the device was attempting to update the content.
+	 * The solution is to read the register again. Do this only
+	 * MMA7660_I2C_READ_RETRIES times to avoid spending too much time
+	 * in the kernel.
+	 */
+	do {
+		ret = i2c_smbus_read_byte_data(client, address);
+		if (ret < 0) {
+			dev_err(&client->dev, "register read failed\n");
+			return ret;
+		}
+	} while (retries-- > 0 && ret & MMA7660_REG_OUT_BIT_ALERT);
+
+	if (ret & MMA7660_REG_OUT_BIT_ALERT) {
+		dev_err(&client->dev, "all register read retries failed\n");
+		return -ETIMEDOUT;
+	}
+
+	return ret;
+}
+
+static int mma7660_read_raw(struct iio_dev *indio_dev,
+				struct iio_chan_spec const *chan,
+				int *val, int *val2, long mask)
+{
+	struct mma7660_data *data = iio_priv(indio_dev);
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		mutex_lock(&data->lock);
+		ret = mma7660_read_accel(data, chan->address);
+		mutex_unlock(&data->lock);
+		if (ret < 0)
+			return ret;
+		*val = sign_extend32(ret, 5);
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		*val = 0;
+		*val2 = mma7660_nscale;
+		return IIO_VAL_INT_PLUS_NANO;
+	default:
+		return -EINVAL;
+	}
+
+	return -EINVAL;
+}
+
+static const struct iio_info mma7660_info = {
+	.driver_module	= THIS_MODULE,
+	.read_raw		= mma7660_read_raw,
+	.attrs			= &mma7660_attribute_group,
+};
+
+static int mma7660_probe(struct i2c_client *client,
+			const struct i2c_device_id *id)
+{
+	int ret;
+	struct iio_dev *indio_dev;
+	struct mma7660_data *data;
+
+	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);
+	mutex_init(&data->lock);
+	data->mode = MMA7660_MODE_STANDBY;
+
+	indio_dev->dev.parent = &client->dev;
+	indio_dev->info = &mma7660_info;
+	indio_dev->name = MMA7660_DRIVER_NAME;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->channels = mma7660_channels;
+	indio_dev->num_channels = ARRAY_SIZE(mma7660_channels);
+
+	ret = mma7660_set_mode(data, MMA7660_MODE_ACTIVE);
+	if (ret < 0)
+		return ret;
+
+	ret = iio_device_register(indio_dev);
+	if (ret < 0) {
+		dev_err(&client->dev, "device_register failed\n");
+		mma7660_set_mode(data, MMA7660_MODE_STANDBY);
+	}
+
+	return ret;
+}
+
+static int mma7660_remove(struct i2c_client *client)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(client);
+
+	iio_device_unregister(indio_dev);
+
+	return mma7660_set_mode(iio_priv(indio_dev), MMA7660_MODE_STANDBY);
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int mma7660_suspend(struct device *dev)
+{
+	struct mma7660_data *data;
+
+	data = iio_priv(i2c_get_clientdata(to_i2c_client(dev)));
+
+	return mma7660_set_mode(data, MMA7660_MODE_STANDBY);
+}
+
+static int mma7660_resume(struct device *dev)
+{
+	struct mma7660_data *data;
+
+	data = iio_priv(i2c_get_clientdata(to_i2c_client(dev)));
+
+	return mma7660_set_mode(data, MMA7660_MODE_ACTIVE);
+}
+
+static SIMPLE_DEV_PM_OPS(mma7660_pm_ops, mma7660_suspend, mma7660_resume);
+
+#define MMA7660_PM_OPS (&mma7660_pm_ops)
+#else
+#define MMA7660_PM_OPS NULL
+#endif
+
+static const struct i2c_device_id mma7660_i2c_id[] = {
+	{"mma7660", 0},
+	{}
+};
+
+static const struct acpi_device_id mma7660_acpi_id[] = {
+	{"MMA7660", 0},
+	{}
+};
+
+MODULE_DEVICE_TABLE(acpi, mma7660_acpi_id);
+
+static struct i2c_driver mma7660_driver = {
+	.driver = {
+		.name = "mma7660",
+		.pm = MMA7660_PM_OPS,
+		.acpi_match_table = ACPI_PTR(mma7660_acpi_id),
+	},
+	.probe		= mma7660_probe,
+	.remove		= mma7660_remove,
+	.id_table	= mma7660_i2c_id,
+};
+
+module_i2c_driver(mma7660_driver);
+
+MODULE_AUTHOR("Constantin Musca <constantin.musca@intel.com>");
+MODULE_DESCRIPTION("Freescale MMA7660FC 3-Axis Accelerometer driver");
+MODULE_LICENSE("GPL v2");