iio: Add Freescale MMA8452Q 3-axis accelerometer driver

3-axis accelerometer sensor (2/4/8 g) with 12-bit resolution
and I2C interface

many extra features are unsupported (freefall detection, orientation
change, autosleep)

datasheet is here:
http://cache.freescale.com/files/sensors/doc/data_sheet/MMA8452Q.pdf

v2: (thanks to Jonathan Cameron)
* use ARRAY_SIZE()
Signed-off-by: Peter Meerwald <pmeerw@pmeerw.net>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/accel/Kconfig

@@ -65,4 +65,16 @@ config KXSD9
 	  Say yes here to build support for the Kionix KXSD9 accelerometer.
 	  Currently this only supports the device via an SPI interface.
 
+config MMA8452
+	tristate "Freescale MMA8452Q Accelerometer Driver"
+	depends on I2C
+	select IIO_BUFFER
+	select IIO_TRIGGERED_BUFFER
+	help
+	  Say yes here to build support for the Freescale MMA8452Q 3-axis
+	  accelerometer.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called mma8452.
+
 endmenu

drivers/iio/accel/Makefile

@@ -6,6 +6,7 @@
 obj-$(CONFIG_BMA180) += bma180.o
 obj-$(CONFIG_HID_SENSOR_ACCEL_3D) += hid-sensor-accel-3d.o
 obj-$(CONFIG_KXSD9)	+= kxsd9.o
+obj-$(CONFIG_MMA8452)	+= mma8452.o
 
 obj-$(CONFIG_IIO_ST_ACCEL_3AXIS) += st_accel.o
 st_accel-y := st_accel_core.o

drivers/iio/accel/mma8452.c

+/*
+ * mma8452.c - Support for Freescale MMA8452Q 3-axis 12-bit accelerometer
+ *
+ * Copyright 2014 Peter Meerwald <pmeerw@pmeerw.net>
+ *
+ * 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.
+ *
+ * 7-bit I2C slave address 0x1c/0x1d (pin selectable)
+ *
+ * TODO: interrupt, thresholding, orientation / freefall events, autosleep
+ */
+
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/triggered_buffer.h>
+#include <linux/delay.h>
+
+#define MMA8452_STATUS 0x00
+#define MMA8452_OUT_X 0x01 /* MSB first, 12-bit  */
+#define MMA8452_OUT_Y 0x03
+#define MMA8452_OUT_Z 0x05
+#define MMA8452_WHO_AM_I 0x0d
+#define MMA8452_DATA_CFG 0x0e
+#define MMA8452_OFF_X 0x2f
+#define MMA8452_OFF_Y 0x30
+#define MMA8452_OFF_Z 0x31
+#define MMA8452_CTRL_REG1 0x2a
+#define MMA8452_CTRL_REG2 0x2b
+
+#define MMA8452_STATUS_DRDY (BIT(2) | BIT(1) | BIT(0))
+
+#define MMA8452_CTRL_DR_MASK (BIT(5) | BIT(4) | BIT(3))
+#define MMA8452_CTRL_DR_SHIFT 3
+#define MMA8452_CTRL_DR_DEFAULT 0x4 /* 50 Hz sample frequency */
+#define MMA8452_CTRL_ACTIVE BIT(0)
+
+#define MMA8452_DATA_CFG_FS_MASK (BIT(1) | BIT(0))
+#define MMA8452_DATA_CFG_FS_2G 0
+#define MMA8452_DATA_CFG_FS_4G 1
+#define MMA8452_DATA_CFG_FS_8G 2
+
+#define MMA8452_DEVICE_ID 0x2a
+
+struct mma8452_data {
+	struct i2c_client *client;
+	struct mutex lock;
+	u8 ctrl_reg1;
+	u8 data_cfg;
+};
+
+static int mma8452_drdy(struct mma8452_data *data)
+{
+	int tries = 150;
+
+	while (tries-- > 0) {
+		int ret = i2c_smbus_read_byte_data(data->client,
+			MMA8452_STATUS);
+		if (ret < 0)
+			return ret;
+		if ((ret & MMA8452_STATUS_DRDY) == MMA8452_STATUS_DRDY)
+			return 0;
+		msleep(20);
+	}
+
+	dev_err(&data->client->dev, "data not ready\n");
+	return -EIO;
+}
+
+static int mma8452_read(struct mma8452_data *data, __be16 buf[3])
+{
+	int ret = mma8452_drdy(data);
+	if (ret < 0)
+		return ret;
+	return i2c_smbus_read_i2c_block_data(data->client,
+		MMA8452_OUT_X, 3 * sizeof(__be16), (u8 *) buf);
+}
+
+static ssize_t mma8452_show_int_plus_micros(char *buf,
+	const int (*vals)[2], int n)
+{
+	size_t len = 0;
+
+	while (n-- > 0)
+		len += scnprintf(buf + len, PAGE_SIZE - len,
+			"%d.%06d ", vals[n][0], vals[n][1]);
+
+	/* replace trailing space by newline */
+	buf[len - 1] = '\n';
+
+	return len;
+}
+
+static int mma8452_get_int_plus_micros_index(const int (*vals)[2], int n,
+					int val, int val2)
+{
+	while (n-- > 0)
+		if (val == vals[n][0] && val2 == vals[n][1])
+			return n;
+
+	return -EINVAL;
+}
+
+static const int mma8452_samp_freq[8][2] = {
+	{800, 0}, {400, 0}, {200, 0}, {100, 0}, {50, 0}, {12, 500000},
+	{6, 250000}, {1, 560000}
+};
+
+static const int mma8452_scales[3][2] = {
+	{0, 977}, {0, 1953}, {0, 3906}
+};
+
+static ssize_t mma8452_show_samp_freq_avail(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	return mma8452_show_int_plus_micros(buf, mma8452_samp_freq,
+		ARRAY_SIZE(mma8452_samp_freq));
+}
+
+static ssize_t mma8452_show_scale_avail(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	return mma8452_show_int_plus_micros(buf, mma8452_scales,
+		ARRAY_SIZE(mma8452_scales));
+}
+
+static IIO_DEV_ATTR_SAMP_FREQ_AVAIL(mma8452_show_samp_freq_avail);
+static IIO_DEVICE_ATTR(in_accel_scale_available, S_IRUGO,
+	mma8452_show_scale_avail, NULL, 0);
+
+static int mma8452_get_samp_freq_index(struct mma8452_data *data,
+	int val, int val2)
+{
+	return mma8452_get_int_plus_micros_index(mma8452_samp_freq,
+		ARRAY_SIZE(mma8452_samp_freq), val, val2);
+}
+
+static int mma8452_get_scale_index(struct mma8452_data *data,
+	int val, int val2)
+{
+	return mma8452_get_int_plus_micros_index(mma8452_scales,
+		ARRAY_SIZE(mma8452_scales), val, val2);
+}
+
+static int mma8452_read_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan,
+			    int *val, int *val2, long mask)
+{
+	struct mma8452_data *data = iio_priv(indio_dev);
+	__be16 buffer[3];
+	int i, ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		if (iio_buffer_enabled(indio_dev))
+			return -EBUSY;
+
+		mutex_lock(&data->lock);
+		ret = mma8452_read(data, buffer);
+		mutex_unlock(&data->lock);
+		if (ret < 0)
+			return ret;
+		*val = sign_extend32(
+			be16_to_cpu(buffer[chan->scan_index]) >> 4, 11);
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		i = data->data_cfg & MMA8452_DATA_CFG_FS_MASK;
+		*val = mma8452_scales[i][0];
+		*val2 = mma8452_scales[i][1];
+		return IIO_VAL_INT_PLUS_MICRO;
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		i = (data->ctrl_reg1 & MMA8452_CTRL_DR_MASK) >>
+			MMA8452_CTRL_DR_SHIFT;
+		*val = mma8452_samp_freq[i][0];
+		*val2 = mma8452_samp_freq[i][1];
+		return IIO_VAL_INT_PLUS_MICRO;
+	case IIO_CHAN_INFO_CALIBBIAS:
+		ret = i2c_smbus_read_byte_data(data->client, MMA8452_OFF_X +
+			chan->scan_index);
+		if (ret < 0)
+			return ret;
+		*val = sign_extend32(ret, 7);
+		return IIO_VAL_INT;
+	}
+	return -EINVAL;
+}
+
+static int mma8452_standby(struct mma8452_data *data)
+{
+	return i2c_smbus_write_byte_data(data->client, MMA8452_CTRL_REG1,
+		data->ctrl_reg1 & ~MMA8452_CTRL_ACTIVE);
+}
+
+static int mma8452_active(struct mma8452_data *data)
+{
+	return i2c_smbus_write_byte_data(data->client, MMA8452_CTRL_REG1,
+		data->ctrl_reg1);
+}
+
+static int mma8452_change_config(struct mma8452_data *data, u8 reg, u8 val)
+{
+	int ret;
+
+	mutex_lock(&data->lock);
+
+	/* config can only be changed when in standby */
+	ret = mma8452_standby(data);
+	if (ret < 0)
+		goto fail;
+
+	ret = i2c_smbus_write_byte_data(data->client, reg, val);
+	if (ret < 0)
+		goto fail;
+
+	ret = mma8452_active(data);
+	if (ret < 0)
+		goto fail;
+
+	ret = 0;
+fail:
+	mutex_unlock(&data->lock);
+	return ret;
+}
+
+static int mma8452_write_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan,
+			     int val, int val2, long mask)
+{
+	struct mma8452_data *data = iio_priv(indio_dev);
+	int i;
+
+	if (iio_buffer_enabled(indio_dev))
+		return -EBUSY;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		i = mma8452_get_samp_freq_index(data, val, val2);
+		if (i < 0)
+			return -EINVAL;
+
+		data->ctrl_reg1 &= ~MMA8452_CTRL_DR_MASK;
+		data->ctrl_reg1 |= i << MMA8452_CTRL_DR_SHIFT;
+		return mma8452_change_config(data, MMA8452_CTRL_REG1,
+			data->ctrl_reg1);
+	case IIO_CHAN_INFO_SCALE:
+		i = mma8452_get_scale_index(data, val, val2);
+		if (i < 0)
+			return -EINVAL;
+		data->data_cfg &= ~MMA8452_DATA_CFG_FS_MASK;
+		data->data_cfg |= i;
+		return mma8452_change_config(data, MMA8452_DATA_CFG,
+			data->data_cfg);
+	case IIO_CHAN_INFO_CALIBBIAS:
+		if (val < -128 || val > 127)
+			return -EINVAL;
+		return mma8452_change_config(data, MMA8452_OFF_X +
+			chan->scan_index, val);
+	default:
+		return -EINVAL;
+	}
+}
+
+static irqreturn_t mma8452_trigger_handler(int irq, void *p)
+{
+	struct iio_poll_func *pf = p;
+	struct iio_dev *indio_dev = pf->indio_dev;
+	struct mma8452_data *data = iio_priv(indio_dev);
+	u8 buffer[16]; /* 3 16-bit channels + padding + ts */
+	int ret;
+
+	ret = mma8452_read(data, (__be16 *) buffer);
+	if (ret < 0)
+		goto done;
+
+	iio_push_to_buffers_with_timestamp(indio_dev, buffer,
+		iio_get_time_ns());
+
+done:
+	iio_trigger_notify_done(indio_dev->trig);
+	return IRQ_HANDLED;
+}
+
+#define MMA8452_CHANNEL(axis, idx) { \
+	.type = IIO_ACCEL, \
+	.modified = 1, \
+	.channel2 = IIO_MOD_##axis, \
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
+		BIT(IIO_CHAN_INFO_CALIBBIAS), \
+	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ) | \
+		BIT(IIO_CHAN_INFO_SCALE), \
+	.scan_index = idx, \
+	.scan_type = { \
+		.sign = 's', \
+		.realbits = 12, \
+		.storagebits = 16, \
+		.shift = 4, \
+		.endianness = IIO_BE, \
+	}, \
+}
+
+static const struct iio_chan_spec mma8452_channels[] = {
+	MMA8452_CHANNEL(X, 0),
+	MMA8452_CHANNEL(Y, 1),
+	MMA8452_CHANNEL(Z, 2),
+	IIO_CHAN_SOFT_TIMESTAMP(3),
+};
+
+static struct attribute *mma8452_attributes[] = {
+	&iio_dev_attr_sampling_frequency_available.dev_attr.attr,
+	&iio_dev_attr_in_accel_scale_available.dev_attr.attr,
+	NULL
+};
+
+static const struct attribute_group mma8452_group = {
+	.attrs = mma8452_attributes,
+};
+
+static const struct iio_info mma8452_info = {
+	.attrs = &mma8452_group,
+	.read_raw = &mma8452_read_raw,
+	.write_raw = &mma8452_write_raw,
+	.driver_module = THIS_MODULE,
+};
+
+static const unsigned long mma8452_scan_masks[] = {0x7, 0};
+
+static int mma8452_probe(struct i2c_client *client,
+			 const struct i2c_device_id *id)
+{
+	struct mma8452_data *data;
+	struct iio_dev *indio_dev;
+	int ret;
+
+	ret = i2c_smbus_read_byte_data(client, MMA8452_WHO_AM_I);
+	if (ret < 0)
+		return ret;
+	if (ret != MMA8452_DEVICE_ID)
+		return -ENODEV;
+
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	data = iio_priv(indio_dev);
+	data->client = client;
+	mutex_init(&data->lock);
+
+	i2c_set_clientdata(client, indio_dev);
+	indio_dev->info = &mma8452_info;
+	indio_dev->name = id->name;
+	indio_dev->dev.parent = &client->dev;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->channels = mma8452_channels;
+	indio_dev->num_channels = ARRAY_SIZE(mma8452_channels);
+	indio_dev->available_scan_masks = mma8452_scan_masks;
+
+	data->ctrl_reg1 = MMA8452_CTRL_ACTIVE |
+		(MMA8452_CTRL_DR_DEFAULT << MMA8452_CTRL_DR_SHIFT);
+	ret = i2c_smbus_write_byte_data(client, MMA8452_CTRL_REG1,
+		data->ctrl_reg1);
+	if (ret < 0)
+		return ret;
+
+	data->data_cfg = MMA8452_DATA_CFG_FS_2G;
+	ret = i2c_smbus_write_byte_data(client, MMA8452_DATA_CFG,
+		data->data_cfg);
+	if (ret < 0)
+		return ret;
+
+	ret = iio_triggered_buffer_setup(indio_dev, NULL,
+		mma8452_trigger_handler, NULL);
+	if (ret < 0)
+		return ret;
+
+	ret = iio_device_register(indio_dev);
+	if (ret < 0)
+		goto buffer_cleanup;
+	return 0;
+
+buffer_cleanup:
+	iio_triggered_buffer_cleanup(indio_dev);
+	return ret;
+}
+
+static int mma8452_remove(struct i2c_client *client)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(client);
+
+	iio_device_unregister(indio_dev);
+	iio_triggered_buffer_cleanup(indio_dev);
+	mma8452_standby(iio_priv(indio_dev));
+
+	return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int mma8452_suspend(struct device *dev)
+{
+	return mma8452_standby(iio_priv(i2c_get_clientdata(
+		to_i2c_client(dev))));
+}
+
+static int mma8452_resume(struct device *dev)
+{
+	return mma8452_active(iio_priv(i2c_get_clientdata(
+		to_i2c_client(dev))));
+}
+
+static SIMPLE_DEV_PM_OPS(mma8452_pm_ops, mma8452_suspend, mma8452_resume);
+#define MMA8452_PM_OPS (&mma8452_pm_ops)
+#else
+#define MMA8452_PM_OPS NULL
+#endif
+
+static const struct i2c_device_id mma8452_id[] = {
+	{ "mma8452", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, mma8452_id);
+
+static struct i2c_driver mma8452_driver = {
+	.driver = {
+		.name	= "mma8452",
+		.pm	= MMA8452_PM_OPS,
+	},
+	.probe = mma8452_probe,
+	.remove = mma8452_remove,
+	.id_table = mma8452_id,
+};
+module_i2c_driver(mma8452_driver);
+
+MODULE_AUTHOR("Peter Meerwald <pmeerw@pmeerw.net>");
+MODULE_DESCRIPTION("Freescale MMA8452 accelerometer driver");
+MODULE_LICENSE("GPL");