Merge tag 'iio-for-4.5a' of git://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio into staging-next

Jonathan writes:

First set of new device support, features and cleanups for IIO in the 4.5 cycle

Usual mixed bag, but the big item perhaps in this series is the DMA buffer
support added by Lars-Peter Clausen. It's been in the works for a long time
and it will be interesting to see what hardware support shows up now that
this is available.

New core features + associate cleanup.
* Add generic DMA buffer infrastructure
* Add a DMAengine framework based buffer
 Also associated minor changes.
   - Set the device buffer watermark based on the minimum watermark for all
     attached buffers rather than just the 'primary' one.
   - iio_buffer_init - only set the watermark default if one hasn't already
     been provided.  This allows simple support for devices with a fixed
     watermark.
   - read only attribute for watermark on fixed watermark devices.
   - add explicit buffer enable/disable callbacks to allow the buffer to
     do more than trivial actions when it is being turned on and off.
* IIO_VAL_INT support in write_raw_get_fmt function.

New device support
* Freescale MMA7455/7456L accelerometers
* Memsic MXC6255XC accelerometer
* ST lis2dh12 accelerometer
* TI ADS8688 ADC
* TI Palamas (twl6035/7) gpadc

New driver features
* mma8452
  - support either of the available interrupt pins to cope with the case
    where board layout has lead to a particular one being connected.

Staging graduation
* Dummy driver
  - this driver acts as both an example and a test device for those with
    out hardware to develop userspace code against.

Cleanups and minor bits and bobs.
* treewide
  - Sort out the ordering of iio_device_register/unregister vs runtime
    pm function calls so that it's all nice and consistent and not race
    prone.
  - Check sscanf return values.  None of the cases will actually happen as
    the strings are supplied internally, but best to be consistent on this.
* ad7780
  - switch over to the gpio descriptor interface and remove the now unused
    platform data which gets rid of a header entirely.
* ad7793
  - drop a pointless else statement.
* at91_adc
  - Swap kmalloc_array in for a kmalloc doing the same job.
* dummy
  - get rid of some commented out lines that snuck in during the move of
    the driver.
* lm3533-als
  - Print an error message on provision of an invalid resistance.
* mcp320x
  - Add compatible strings with vendor prefix and deprecate those with
    no vendor prefix.
* mxs-lradc
  - Use BIT macro in various places rather than shifted ones.
* pa12203001
  - Power off the chip if the registration fails.
* pulsedlight-lidar-lite
  - add runtime PM support.
* xilinx XADC
  - constify an iio_buffer_setup_ops structure.

1 files changed, 747 insertions, 0 deletions

diff --git a/drivers/iio/dummy/iio_simple_dummy.c b/drivers/iio/dummy/iio_simple_dummy.c
new file mode 100644
index 000000000000..43fe4ba7d0dc
--- /dev/null
+++ b/drivers/iio/dummy/iio_simple_dummy.c
@@ -0,0 +1,747 @@
+/**
+ * Copyright (c) 2011 Jonathan Cameron
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ * A reference industrial I/O driver to illustrate the functionality available.
+ *
+ * There are numerous real drivers to illustrate the finer points.
+ * The purpose of this driver is to provide a driver with far more comments
+ * and explanatory notes than any 'real' driver would have.
+ * Anyone starting out writing an IIO driver should first make sure they
+ * understand all of this driver except those bits specifically marked
+ * as being present to allow us to 'fake' the presence of hardware.
+ */
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/iio/events.h>
+#include <linux/iio/buffer.h>
+#include "iio_simple_dummy.h"
+
+/*
+ * A few elements needed to fake a bus for this driver
+ * Note instances parameter controls how many of these
+ * dummy devices are registered.
+ */
+static unsigned instances = 1;
+module_param(instances, uint, 0);
+
+/* Pointer array used to fake bus elements */
+static struct iio_dev **iio_dummy_devs;
+
+/* Fake a name for the part number, usually obtained from the id table */
+static const char *iio_dummy_part_number = "iio_dummy_part_no";
+
+/**
+ * struct iio_dummy_accel_calibscale - realworld to register mapping
+ * @val: first value in read_raw - here integer part.
+ * @val2: second value in read_raw etc - here micro part.
+ * @regval: register value - magic device specific numbers.
+ */
+struct iio_dummy_accel_calibscale {
+	int val;
+	int val2;
+	int regval; /* what would be written to hardware */
+};
+
+static const struct iio_dummy_accel_calibscale dummy_scales[] = {
+	{ 0, 100, 0x8 }, /* 0.000100 */
+	{ 0, 133, 0x7 }, /* 0.000133 */
+	{ 733, 13, 0x9 }, /* 733.000013 */
+};
+
+#ifdef CONFIG_IIO_SIMPLE_DUMMY_EVENTS
+
+/*
+ * simple event - triggered when value rises above
+ * a threshold
+ */
+static const struct iio_event_spec iio_dummy_event = {
+	.type = IIO_EV_TYPE_THRESH,
+	.dir = IIO_EV_DIR_RISING,
+	.mask_separate = BIT(IIO_EV_INFO_VALUE) | BIT(IIO_EV_INFO_ENABLE),
+};
+
+/*
+ * simple step detect event - triggered when a step is detected
+ */
+static const struct iio_event_spec step_detect_event = {
+	.type = IIO_EV_TYPE_CHANGE,
+	.dir = IIO_EV_DIR_NONE,
+	.mask_separate = BIT(IIO_EV_INFO_ENABLE),
+};
+
+/*
+ * simple transition event - triggered when the reported running confidence
+ * value rises above a threshold value
+ */
+static const struct iio_event_spec iio_running_event = {
+	.type = IIO_EV_TYPE_THRESH,
+	.dir = IIO_EV_DIR_RISING,
+	.mask_separate = BIT(IIO_EV_INFO_VALUE) | BIT(IIO_EV_INFO_ENABLE),
+};
+
+/*
+ * simple transition event - triggered when the reported walking confidence
+ * value falls under a threshold value
+ */
+static const struct iio_event_spec iio_walking_event = {
+	.type = IIO_EV_TYPE_THRESH,
+	.dir = IIO_EV_DIR_FALLING,
+	.mask_separate = BIT(IIO_EV_INFO_VALUE) | BIT(IIO_EV_INFO_ENABLE),
+};
+#endif
+
+/*
+ * iio_dummy_channels - Description of available channels
+ *
+ * This array of structures tells the IIO core about what the device
+ * actually provides for a given channel.
+ */
+static const struct iio_chan_spec iio_dummy_channels[] = {
+	/* indexed ADC channel in_voltage0_raw etc */
+	{
+		.type = IIO_VOLTAGE,
+		/* Channel has a numeric index of 0 */
+		.indexed = 1,
+		.channel = 0,
+		/* What other information is available? */
+		.info_mask_separate =
+		/*
+		 * in_voltage0_raw
+		 * Raw (unscaled no bias removal etc) measurement
+		 * from the device.
+		 */
+		BIT(IIO_CHAN_INFO_RAW) |
+		/*
+		 * in_voltage0_offset
+		 * Offset for userspace to apply prior to scale
+		 * when converting to standard units (microvolts)
+		 */
+		BIT(IIO_CHAN_INFO_OFFSET) |
+		/*
+		 * in_voltage0_scale
+		 * Multipler for userspace to apply post offset
+		 * when converting to standard units (microvolts)
+		 */
+		BIT(IIO_CHAN_INFO_SCALE),
+		/*
+		 * sampling_frequency
+		 * The frequency in Hz at which the channels are sampled
+		 */
+		.info_mask_shared_by_dir = BIT(IIO_CHAN_INFO_SAMP_FREQ),
+		/* The ordering of elements in the buffer via an enum */
+		.scan_index = DUMMY_INDEX_VOLTAGE_0,
+		.scan_type = { /* Description of storage in buffer */
+			.sign = 'u', /* unsigned */
+			.realbits = 13, /* 13 bits */
+			.storagebits = 16, /* 16 bits used for storage */
+			.shift = 0, /* zero shift */
+		},
+#ifdef CONFIG_IIO_SIMPLE_DUMMY_EVENTS
+		.event_spec = &iio_dummy_event,
+		.num_event_specs = 1,
+#endif /* CONFIG_IIO_SIMPLE_DUMMY_EVENTS */
+	},
+	/* Differential ADC channel in_voltage1-voltage2_raw etc*/
+	{
+		.type = IIO_VOLTAGE,
+		.differential = 1,
+		/*
+		 * Indexing for differential channels uses channel
+		 * for the positive part, channel2 for the negative.
+		 */
+		.indexed = 1,
+		.channel = 1,
+		.channel2 = 2,
+		/*
+		 * in_voltage1-voltage2_raw
+		 * Raw (unscaled no bias removal etc) measurement
+		 * from the device.
+		 */
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+		/*
+		 * in_voltage-voltage_scale
+		 * Shared version of scale - shared by differential
+		 * input channels of type IIO_VOLTAGE.
+		 */
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
+		/*
+		 * sampling_frequency
+		 * The frequency in Hz at which the channels are sampled
+		 */
+		.scan_index = DUMMY_INDEX_DIFFVOLTAGE_1M2,
+		.scan_type = { /* Description of storage in buffer */
+			.sign = 's', /* signed */
+			.realbits = 12, /* 12 bits */
+			.storagebits = 16, /* 16 bits used for storage */
+			.shift = 0, /* zero shift */
+		},
+	},
+	/* Differential ADC channel in_voltage3-voltage4_raw etc*/
+	{
+		.type = IIO_VOLTAGE,
+		.differential = 1,
+		.indexed = 1,
+		.channel = 3,
+		.channel2 = 4,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
+		.info_mask_shared_by_dir = BIT(IIO_CHAN_INFO_SAMP_FREQ),
+		.scan_index = DUMMY_INDEX_DIFFVOLTAGE_3M4,
+		.scan_type = {
+			.sign = 's',
+			.realbits = 11,
+			.storagebits = 16,
+			.shift = 0,
+		},
+	},
+	/*
+	 * 'modified' (i.e. axis specified) acceleration channel
+	 * in_accel_z_raw
+	 */
+	{
+		.type = IIO_ACCEL,
+		.modified = 1,
+		/* Channel 2 is use for modifiers */
+		.channel2 = IIO_MOD_X,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+		/*
+		 * Internal bias and gain correction values. Applied
+		 * by the hardware or driver prior to userspace
+		 * seeing the readings. Typically part of hardware
+		 * calibration.
+		 */
+		BIT(IIO_CHAN_INFO_CALIBSCALE) |
+		BIT(IIO_CHAN_INFO_CALIBBIAS),
+		.info_mask_shared_by_dir = BIT(IIO_CHAN_INFO_SAMP_FREQ),
+		.scan_index = DUMMY_INDEX_ACCELX,
+		.scan_type = { /* Description of storage in buffer */
+			.sign = 's', /* signed */
+			.realbits = 16, /* 16 bits */
+			.storagebits = 16, /* 16 bits used for storage */
+			.shift = 0, /* zero shift */
+		},
+	},
+	/*
+	 * Convenience macro for timestamps. 4 is the index in
+	 * the buffer.
+	 */
+	IIO_CHAN_SOFT_TIMESTAMP(4),
+	/* DAC channel out_voltage0_raw */
+	{
+		.type = IIO_VOLTAGE,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+		.scan_index = -1, /* No buffer support */
+		.output = 1,
+		.indexed = 1,
+		.channel = 0,
+	},
+	{
+		.type = IIO_STEPS,
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_ENABLE) |
+			BIT(IIO_CHAN_INFO_CALIBHEIGHT),
+		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
+		.scan_index = -1, /* No buffer support */
+#ifdef CONFIG_IIO_SIMPLE_DUMMY_EVENTS
+		.event_spec = &step_detect_event,
+		.num_event_specs = 1,
+#endif /* CONFIG_IIO_SIMPLE_DUMMY_EVENTS */
+	},
+	{
+		.type = IIO_ACTIVITY,
+		.modified = 1,
+		.channel2 = IIO_MOD_RUNNING,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
+		.scan_index = -1, /* No buffer support */
+#ifdef CONFIG_IIO_SIMPLE_DUMMY_EVENTS
+		.event_spec = &iio_running_event,
+		.num_event_specs = 1,
+#endif /* CONFIG_IIO_SIMPLE_DUMMY_EVENTS */
+	},
+	{
+		.type = IIO_ACTIVITY,
+		.modified = 1,
+		.channel2 = IIO_MOD_WALKING,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
+		.scan_index = -1, /* No buffer support */
+#ifdef CONFIG_IIO_SIMPLE_DUMMY_EVENTS
+		.event_spec = &iio_walking_event,
+		.num_event_specs = 1,
+#endif /* CONFIG_IIO_SIMPLE_DUMMY_EVENTS */
+	},
+};
+
+/**
+ * iio_dummy_read_raw() - data read function.
+ * @indio_dev:	the struct iio_dev associated with this device instance
+ * @chan:	the channel whose data is to be read
+ * @val:	first element of returned value (typically INT)
+ * @val2:	second element of returned value (typically MICRO)
+ * @mask:	what we actually want to read as per the info_mask_*
+ *		in iio_chan_spec.
+ */
+static int iio_dummy_read_raw(struct iio_dev *indio_dev,
+			      struct iio_chan_spec const *chan,
+			      int *val,
+			      int *val2,
+			      long mask)
+{
+	struct iio_dummy_state *st = iio_priv(indio_dev);
+	int ret = -EINVAL;
+
+	mutex_lock(&st->lock);
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW: /* magic value - channel value read */
+		switch (chan->type) {
+		case IIO_VOLTAGE:
+			if (chan->output) {
+				/* Set integer part to cached value */
+				*val = st->dac_val;
+				ret = IIO_VAL_INT;
+			} else if (chan->differential) {
+				if (chan->channel == 1)
+					*val = st->differential_adc_val[0];
+				else
+					*val = st->differential_adc_val[1];
+				ret = IIO_VAL_INT;
+			} else {
+				*val = st->single_ended_adc_val;
+				ret = IIO_VAL_INT;
+			}
+			break;
+		case IIO_ACCEL:
+			*val = st->accel_val;
+			ret = IIO_VAL_INT;
+			break;
+		default:
+			break;
+		}
+		break;
+	case IIO_CHAN_INFO_PROCESSED:
+		switch (chan->type) {
+		case IIO_STEPS:
+			*val = st->steps;
+			ret = IIO_VAL_INT;
+			break;
+		case IIO_ACTIVITY:
+			switch (chan->channel2) {
+			case IIO_MOD_RUNNING:
+				*val = st->activity_running;
+				ret = IIO_VAL_INT;
+				break;
+			case IIO_MOD_WALKING:
+				*val = st->activity_walking;
+				ret = IIO_VAL_INT;
+				break;
+			default:
+				break;
+			}
+			break;
+		default:
+			break;
+		}
+		break;
+	case IIO_CHAN_INFO_OFFSET:
+		/* only single ended adc -> 7 */
+		*val = 7;
+		ret = IIO_VAL_INT;
+		break;
+	case IIO_CHAN_INFO_SCALE:
+		switch (chan->type) {
+		case IIO_VOLTAGE:
+			switch (chan->differential) {
+			case 0:
+				/* only single ended adc -> 0.001333 */
+				*val = 0;
+				*val2 = 1333;
+				ret = IIO_VAL_INT_PLUS_MICRO;
+				break;
+			case 1:
+				/* all differential adc -> 0.000001344 */
+				*val = 0;
+				*val2 = 1344;
+				ret = IIO_VAL_INT_PLUS_NANO;
+			}
+			break;
+		default:
+			break;
+		}
+		break;
+	case IIO_CHAN_INFO_CALIBBIAS:
+		/* only the acceleration axis - read from cache */
+		*val = st->accel_calibbias;
+		ret = IIO_VAL_INT;
+		break;
+	case IIO_CHAN_INFO_CALIBSCALE:
+		*val = st->accel_calibscale->val;
+		*val2 = st->accel_calibscale->val2;
+		ret = IIO_VAL_INT_PLUS_MICRO;
+		break;
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		*val = 3;
+		*val2 = 33;
+		ret = IIO_VAL_INT_PLUS_NANO;
+		break;
+	case IIO_CHAN_INFO_ENABLE:
+		switch (chan->type) {
+		case IIO_STEPS:
+			*val = st->steps_enabled;
+			ret = IIO_VAL_INT;
+			break;
+		default:
+			break;
+		}
+		break;
+	case IIO_CHAN_INFO_CALIBHEIGHT:
+		switch (chan->type) {
+		case IIO_STEPS:
+			*val = st->height;
+			ret = IIO_VAL_INT;
+			break;
+		default:
+			break;
+		}
+		break;
+
+	default:
+		break;
+	}
+	mutex_unlock(&st->lock);
+	return ret;
+}
+
+/**
+ * iio_dummy_write_raw() - data write function.
+ * @indio_dev:	the struct iio_dev associated with this device instance
+ * @chan:	the channel whose data is to be written
+ * @val:	first element of value to set (typically INT)
+ * @val2:	second element of value to set (typically MICRO)
+ * @mask:	what we actually want to write as per the info_mask_*
+ *		in iio_chan_spec.
+ *
+ * Note that all raw writes are assumed IIO_VAL_INT and info mask elements
+ * are assumed to be IIO_INT_PLUS_MICRO unless the callback write_raw_get_fmt
+ * in struct iio_info is provided by the driver.
+ */
+static int iio_dummy_write_raw(struct iio_dev *indio_dev,
+			       struct iio_chan_spec const *chan,
+			       int val,
+			       int val2,
+			       long mask)
+{
+	int i;
+	int ret = 0;
+	struct iio_dummy_state *st = iio_priv(indio_dev);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		switch (chan->type) {
+		case IIO_VOLTAGE:
+			if (chan->output == 0)
+				return -EINVAL;
+
+			/* Locking not required as writing single value */
+			mutex_lock(&st->lock);
+			st->dac_val = val;
+			mutex_unlock(&st->lock);
+			return 0;
+		default:
+			return -EINVAL;
+		}
+	case IIO_CHAN_INFO_PROCESSED:
+		switch (chan->type) {
+		case IIO_STEPS:
+			mutex_lock(&st->lock);
+			st->steps = val;
+			mutex_unlock(&st->lock);
+			return 0;
+		case IIO_ACTIVITY:
+			if (val < 0)
+				val = 0;
+			if (val > 100)
+				val = 100;
+			switch (chan->channel2) {
+			case IIO_MOD_RUNNING:
+				st->activity_running = val;
+				return 0;
+			case IIO_MOD_WALKING:
+				st->activity_walking = val;
+				return 0;
+			default:
+				return -EINVAL;
+			}
+			break;
+		default:
+			return -EINVAL;
+		}
+	case IIO_CHAN_INFO_CALIBSCALE:
+		mutex_lock(&st->lock);
+		/* Compare against table - hard matching here */
+		for (i = 0; i < ARRAY_SIZE(dummy_scales); i++)
+			if (val == dummy_scales[i].val &&
+			    val2 == dummy_scales[i].val2)
+				break;
+		if (i == ARRAY_SIZE(dummy_scales))
+			ret = -EINVAL;
+		else
+			st->accel_calibscale = &dummy_scales[i];
+		mutex_unlock(&st->lock);
+		return ret;
+	case IIO_CHAN_INFO_CALIBBIAS:
+		mutex_lock(&st->lock);
+		st->accel_calibbias = val;
+		mutex_unlock(&st->lock);
+		return 0;
+	case IIO_CHAN_INFO_ENABLE:
+		switch (chan->type) {
+		case IIO_STEPS:
+			mutex_lock(&st->lock);
+			st->steps_enabled = val;
+			mutex_unlock(&st->lock);
+			return 0;
+		default:
+			return -EINVAL;
+		}
+	case IIO_CHAN_INFO_CALIBHEIGHT:
+		switch (chan->type) {
+		case IIO_STEPS:
+			st->height = val;
+			return 0;
+		default:
+			return -EINVAL;
+		}
+
+	default:
+		return -EINVAL;
+	}
+}
+
+/*
+ * Device type specific information.
+ */
+static const struct iio_info iio_dummy_info = {
+	.driver_module = THIS_MODULE,
+	.read_raw = &iio_dummy_read_raw,
+	.write_raw = &iio_dummy_write_raw,
+#ifdef CONFIG_IIO_SIMPLE_DUMMY_EVENTS
+	.read_event_config = &iio_simple_dummy_read_event_config,
+	.write_event_config = &iio_simple_dummy_write_event_config,
+	.read_event_value = &iio_simple_dummy_read_event_value,
+	.write_event_value = &iio_simple_dummy_write_event_value,
+#endif /* CONFIG_IIO_SIMPLE_DUMMY_EVENTS */
+};
+
+/**
+ * iio_dummy_init_device() - device instance specific init
+ * @indio_dev: the iio device structure
+ *
+ * Most drivers have one of these to set up default values,
+ * reset the device to known state etc.
+ */
+static int iio_dummy_init_device(struct iio_dev *indio_dev)
+{
+	struct iio_dummy_state *st = iio_priv(indio_dev);
+
+	st->dac_val = 0;
+	st->single_ended_adc_val = 73;
+	st->differential_adc_val[0] = 33;
+	st->differential_adc_val[1] = -34;
+	st->accel_val = 34;
+	st->accel_calibbias = -7;
+	st->accel_calibscale = &dummy_scales[0];
+	st->steps = 47;
+	st->activity_running = 98;
+	st->activity_walking = 4;
+
+	return 0;
+}
+
+/**
+ * iio_dummy_probe() - device instance probe
+ * @index: an id number for this instance.
+ *
+ * Arguments are bus type specific.
+ * I2C: iio_dummy_probe(struct i2c_client *client,
+ *                      const struct i2c_device_id *id)
+ * SPI: iio_dummy_probe(struct spi_device *spi)
+ */
+static int iio_dummy_probe(int index)
+{
+	int ret;
+	struct iio_dev *indio_dev;
+	struct iio_dummy_state *st;
+
+	/*
+	 * Allocate an IIO device.
+	 *
+	 * This structure contains all generic state
+	 * information about the device instance.
+	 * It also has a region (accessed by iio_priv()
+	 * for chip specific state information.
+	 */
+	indio_dev = iio_device_alloc(sizeof(*st));
+	if (!indio_dev) {
+		ret = -ENOMEM;
+		goto error_ret;
+	}
+
+	st = iio_priv(indio_dev);
+	mutex_init(&st->lock);
+
+	iio_dummy_init_device(indio_dev);
+	/*
+	 * With hardware: Set the parent device.
+	 * indio_dev->dev.parent = &spi->dev;
+	 * indio_dev->dev.parent = &client->dev;
+	 */
+
+	 /*
+	 * Make the iio_dev struct available to remove function.
+	 * Bus equivalents
+	 * i2c_set_clientdata(client, indio_dev);
+	 * spi_set_drvdata(spi, indio_dev);
+	 */
+	iio_dummy_devs[index] = indio_dev;
+
+	/*
+	 * Set the device name.
+	 *
+	 * This is typically a part number and obtained from the module
+	 * id table.
+	 * e.g. for i2c and spi:
+	 *    indio_dev->name = id->name;
+	 *    indio_dev->name = spi_get_device_id(spi)->name;
+	 */
+	indio_dev->name = iio_dummy_part_number;
+
+	/* Provide description of available channels */
+	indio_dev->channels = iio_dummy_channels;
+	indio_dev->num_channels = ARRAY_SIZE(iio_dummy_channels);
+
+	/*
+	 * Provide device type specific interface functions and
+	 * constant data.
+	 */
+	indio_dev->info = &iio_dummy_info;
+
+	/* Specify that device provides sysfs type interfaces */
+	indio_dev->modes = INDIO_DIRECT_MODE;
+
+	ret = iio_simple_dummy_events_register(indio_dev);
+	if (ret < 0)
+		goto error_free_device;
+
+	ret = iio_simple_dummy_configure_buffer(indio_dev);
+	if (ret < 0)
+		goto error_unregister_events;
+
+	ret = iio_device_register(indio_dev);
+	if (ret < 0)
+		goto error_unconfigure_buffer;
+
+	return 0;
+error_unconfigure_buffer:
+	iio_simple_dummy_unconfigure_buffer(indio_dev);
+error_unregister_events:
+	iio_simple_dummy_events_unregister(indio_dev);
+error_free_device:
+	iio_device_free(indio_dev);
+error_ret:
+	return ret;
+}
+
+/**
+ * iio_dummy_remove() - device instance removal function
+ * @index: device index.
+ *
+ * Parameters follow those of iio_dummy_probe for buses.
+ */
+static void iio_dummy_remove(int index)
+{
+	/*
+	 * Get a pointer to the device instance iio_dev structure
+	 * from the bus subsystem. E.g.
+	 * struct iio_dev *indio_dev = i2c_get_clientdata(client);
+	 * struct iio_dev *indio_dev = spi_get_drvdata(spi);
+	 */
+	struct iio_dev *indio_dev = iio_dummy_devs[index];
+
+	/* Unregister the device */
+	iio_device_unregister(indio_dev);
+
+	/* Device specific code to power down etc */
+
+	/* Buffered capture related cleanup */
+	iio_simple_dummy_unconfigure_buffer(indio_dev);
+
+	iio_simple_dummy_events_unregister(indio_dev);
+
+	/* Free all structures */
+	iio_device_free(indio_dev);
+}
+
+/**
+ * iio_dummy_init() -  device driver registration
+ *
+ * Varies depending on bus type of the device. As there is no device
+ * here, call probe directly. For information on device registration
+ * i2c:
+ * Documentation/i2c/writing-clients
+ * spi:
+ * Documentation/spi/spi-summary
+ */
+static __init int iio_dummy_init(void)
+{
+	int i, ret;
+
+	if (instances > 10) {
+		instances = 1;
+		return -EINVAL;
+	}
+
+	/* Fake a bus */
+	iio_dummy_devs = kcalloc(instances, sizeof(*iio_dummy_devs),
+				 GFP_KERNEL);
+	/* Here we have no actual device so call probe */
+	for (i = 0; i < instances; i++) {
+		ret = iio_dummy_probe(i);
+		if (ret < 0)
+			goto error_remove_devs;
+	}
+	return 0;
+
+error_remove_devs:
+	while (i--)
+		iio_dummy_remove(i);
+
+	kfree(iio_dummy_devs);
+	return ret;
+}
+module_init(iio_dummy_init);
+
+/**
+ * iio_dummy_exit() - device driver removal
+ *
+ * Varies depending on bus type of the device.
+ * As there is no device here, call remove directly.
+ */
+static __exit void iio_dummy_exit(void)
+{
+	int i;
+
+	for (i = 0; i < instances; i++)
+		iio_dummy_remove(i);
+	kfree(iio_dummy_devs);
+}
+module_exit(iio_dummy_exit);
+
+MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>");
+MODULE_DESCRIPTION("IIO dummy driver");
+MODULE_LICENSE("GPL v2");