text: /* The industrial I/O core
   *
   * Copyright (c) 2008 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.
   *
   * Based on elements of hwmon and input subsystems.
   */
  
  #define pr_fmt(fmt) "iio-core: " fmt
  
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/idr.h>
  #include <linux/kdev_t.h>
  #include <linux/err.h>
  #include <linux/device.h>
  #include <linux/fs.h>
  #include <linux/poll.h>
  #include <linux/sched.h>
  #include <linux/wait.h>
  #include <linux/cdev.h>
  #include <linux/slab.h>
  #include <linux/anon_inodes.h>
  #include <linux/debugfs.h>
  #include <linux/mutex.h>
  #include <linux/iio/iio.h>
  #include "iio_core.h"
  #include "iio_core_trigger.h"
  #include <linux/iio/sysfs.h>
  #include <linux/iio/events.h>
  #include <linux/iio/buffer.h>
  #include <linux/iio/buffer_impl.h>
  
  /* IDA to assign each registered device a unique id */
  static DEFINE_IDA(iio_ida);
  
  static dev_t iio_devt;
  
  #define IIO_DEV_MAX 256
  struct bus_type iio_bus_type = {
  	.name = "iio",
  };
  EXPORT_SYMBOL(iio_bus_type);
  
  static struct dentry *iio_debugfs_dentry;
  
  static const char * const iio_direction[] = {
  	[0] = "in",
  	[1] = "out",
  };
  
  static const char * const iio_chan_type_name_spec[] = {
  	[IIO_VOLTAGE] = "voltage",
  	[IIO_CURRENT] = "current",
  	[IIO_POWER] = "power",
  	[IIO_ACCEL] = "accel",
  	[IIO_ANGL_VEL] = "anglvel",
  	[IIO_MAGN] = "magn",
  	[IIO_LIGHT] = "illuminance",
  	[IIO_INTENSITY] = "intensity",
  	[IIO_PROXIMITY] = "proximity",
  	[IIO_TEMP] = "temp",
  	[IIO_INCLI] = "incli",
  	[IIO_ROT] = "rot",
  	[IIO_ANGL] = "angl",
  	[IIO_TIMESTAMP] = "timestamp",
  	[IIO_CAPACITANCE] = "capacitance",
  	[IIO_ALTVOLTAGE] = "altvoltage",
  	[IIO_CCT] = "cct",
  	[IIO_PRESSURE] = "pressure",
  	[IIO_HUMIDITYRELATIVE] = "humidityrelative",
  	[IIO_ACTIVITY] = "activity",
  	[IIO_STEPS] = "steps",
  	[IIO_ENERGY] = "energy",
  	[IIO_DISTANCE] = "distance",
  	[IIO_VELOCITY] = "velocity",
  	[IIO_CONCENTRATION] = "concentration",
  	[IIO_RESISTANCE] = "resistance",
  	[IIO_PH] = "ph",
  	[IIO_UVINDEX] = "uvindex",
  	[IIO_ELECTRICALCONDUCTIVITY] = "electricalconductivity",
  	[IIO_COUNT] = "count",
  	[IIO_INDEX] = "index",
  	[IIO_GRAVITY]  = "gravity",
  };
  
  static const char * const iio_modifier_names[] = {
  	[IIO_MOD_X] = "x",
  	[IIO_MOD_Y] = "y",
  	[IIO_MOD_Z] = "z",
  	[IIO_MOD_X_AND_Y] = "x&y",
  	[IIO_MOD_X_AND_Z] = "x&z",
  	[IIO_MOD_Y_AND_Z] = "y&z",
  	[IIO_MOD_X_AND_Y_AND_Z] = "x&y&z",
  	[IIO_MOD_X_OR_Y] = "x|y",
  	[IIO_MOD_X_OR_Z] = "x|z",
  	[IIO_MOD_Y_OR_Z] = "y|z",
  	[IIO_MOD_X_OR_Y_OR_Z] = "x|y|z",
  	[IIO_MOD_ROOT_SUM_SQUARED_X_Y] = "sqrt(x^2+y^2)",
  	[IIO_MOD_SUM_SQUARED_X_Y_Z] = "x^2+y^2+z^2",
  	[IIO_MOD_LIGHT_BOTH] = "both",
  	[IIO_MOD_LIGHT_IR] = "ir",
  	[IIO_MOD_LIGHT_CLEAR] = "clear",
  	[IIO_MOD_LIGHT_RED] = "red",
  	[IIO_MOD_LIGHT_GREEN] = "green",
  	[IIO_MOD_LIGHT_BLUE] = "blue",
  	[IIO_MOD_LIGHT_UV] = "uv",
  	[IIO_MOD_QUATERNION] = "quaternion",
  	[IIO_MOD_TEMP_AMBIENT] = "ambient",
  	[IIO_MOD_TEMP_OBJECT] = "object",
  	[IIO_MOD_NORTH_MAGN] = "from_north_magnetic",
  	[IIO_MOD_NORTH_TRUE] = "from_north_true",
  	[IIO_MOD_NORTH_MAGN_TILT_COMP] = "from_north_magnetic_tilt_comp",
  	[IIO_MOD_NORTH_TRUE_TILT_COMP] = "from_north_true_tilt_comp",
  	[IIO_MOD_RUNNING] = "running",
  	[IIO_MOD_JOGGING] = "jogging",
  	[IIO_MOD_WALKING] = "walking",
  	[IIO_MOD_STILL] = "still",
  	[IIO_MOD_ROOT_SUM_SQUARED_X_Y_Z] = "sqrt(x^2+y^2+z^2)",
  	[IIO_MOD_I] = "i",
  	[IIO_MOD_Q] = "q",
  	[IIO_MOD_CO2] = "co2",
  	[IIO_MOD_VOC] = "voc",
  };
  
  /* relies on pairs of these shared then separate */
  static const char * const iio_chan_info_postfix[] = {
  	[IIO_CHAN_INFO_RAW] = "raw",
  	[IIO_CHAN_INFO_PROCESSED] = "input",
  	[IIO_CHAN_INFO_SCALE] = "scale",
  	[IIO_CHAN_INFO_OFFSET] = "offset",
  	[IIO_CHAN_INFO_CALIBSCALE] = "calibscale",
  	[IIO_CHAN_INFO_CALIBBIAS] = "calibbias",
  	[IIO_CHAN_INFO_PEAK] = "peak_raw",
  	[IIO_CHAN_INFO_PEAK_SCALE] = "peak_scale",
  	[IIO_CHAN_INFO_QUADRATURE_CORRECTION_RAW] = "quadrature_correction_raw",
  	[IIO_CHAN_INFO_AVERAGE_RAW] = "mean_raw",
  	[IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY]
  	= "filter_low_pass_3db_frequency",
  	[IIO_CHAN_INFO_HIGH_PASS_FILTER_3DB_FREQUENCY]
  	= "filter_high_pass_3db_frequency",
  	[IIO_CHAN_INFO_SAMP_FREQ] = "sampling_frequency",
  	[IIO_CHAN_INFO_FREQUENCY] = "frequency",
  	[IIO_CHAN_INFO_PHASE] = "phase",
  	[IIO_CHAN_INFO_HARDWAREGAIN] = "hardwaregain",
  	[IIO_CHAN_INFO_HYSTERESIS] = "hysteresis",
  	[IIO_CHAN_INFO_INT_TIME] = "integration_time",
  	[IIO_CHAN_INFO_ENABLE] = "en",
  	[IIO_CHAN_INFO_CALIBHEIGHT] = "calibheight",
  	[IIO_CHAN_INFO_CALIBWEIGHT] = "calibweight",
  	[IIO_CHAN_INFO_DEBOUNCE_COUNT] = "debounce_count",
  	[IIO_CHAN_INFO_DEBOUNCE_TIME] = "debounce_time",
  	[IIO_CHAN_INFO_CALIBEMISSIVITY] = "calibemissivity",
  	[IIO_CHAN_INFO_OVERSAMPLING_RATIO] = "oversampling_ratio",
  };
  
  /**
   * iio_find_channel_from_si() - get channel from its scan index
   * @indio_dev:		device
   * @si:			scan index to match
   */
  const struct iio_chan_spec
  *iio_find_channel_from_si(struct iio_dev *indio_dev, int si)
  {
  	int i;
  
  	for (i = 0; i < indio_dev->num_channels; i++)
  		if (indio_dev->channels[i].scan_index == si)
  			return &indio_dev->channels[i];
  	return NULL;
  }
  
  /* This turns up an awful lot */
  ssize_t iio_read_const_attr(struct device *dev,
  			    struct device_attribute *attr,
  			    char *buf)
  {
  	return sprintf(buf, "%s\n", to_iio_const_attr(attr)->string);
  }
  EXPORT_SYMBOL(iio_read_const_attr);
  
  static int iio_device_set_clock(struct iio_dev *indio_dev, clockid_t clock_id)
  {
  	int ret;
  	const struct iio_event_interface *ev_int = indio_dev->event_interface;
  
  	ret = mutex_lock_interruptible(&indio_dev->mlock);
  	if (ret)
  		return ret;
  	if ((ev_int && iio_event_enabled(ev_int)) ||
  	    iio_buffer_enabled(indio_dev)) {
  		mutex_unlock(&indio_dev->mlock);
  		return -EBUSY;
  	}
  	indio_dev->clock_id = clock_id;
  	mutex_unlock(&indio_dev->mlock);
  
  	return 0;
  }
  
  /**
   * iio_get_time_ns() - utility function to get a time stamp for events etc
   * @indio_dev: device
   */
  s64 iio_get_time_ns(const struct iio_dev *indio_dev)
  {
  	struct timespec tp;
  
  	switch (iio_device_get_clock(indio_dev)) {
  	case CLOCK_REALTIME:
  		ktime_get_real_ts(&tp);
  		break;
  	case CLOCK_MONOTONIC:
  		ktime_get_ts(&tp);
  		break;
  	case CLOCK_MONOTONIC_RAW:
  		getrawmonotonic(&tp);
  		break;
  	case CLOCK_REALTIME_COARSE:
  		tp = current_kernel_time();
  		break;
  	case CLOCK_MONOTONIC_COARSE:
  		tp = get_monotonic_coarse();
  		break;
  	case CLOCK_BOOTTIME:
  		get_monotonic_boottime(&tp);
  		break;
  	case CLOCK_TAI:
  		timekeeping_clocktai(&tp);
  		break;
  	default:
  		BUG();
  	}
  
  	return timespec_to_ns(&tp);
  }
  EXPORT_SYMBOL(iio_get_time_ns);
  
  /**
   * iio_get_time_res() - utility function to get time stamp clock resolution in
   *                      nano seconds.
   * @indio_dev: device
   */
  unsigned int iio_get_time_res(const struct iio_dev *indio_dev)
  {
  	switch (iio_device_get_clock(indio_dev)) {
  	case CLOCK_REALTIME:
  	case CLOCK_MONOTONIC:
  	case CLOCK_MONOTONIC_RAW:
  	case CLOCK_BOOTTIME:
  	case CLOCK_TAI:
  		return hrtimer_resolution;
  	case CLOCK_REALTIME_COARSE:
  	case CLOCK_MONOTONIC_COARSE:
  		return LOW_RES_NSEC;
  	default:
  		BUG();
  	}
  }
  EXPORT_SYMBOL(iio_get_time_res);
  
  static int __init iio_init(void)
  {
  	int ret;
  
  	/* Register sysfs bus */
  	ret  = bus_register(&iio_bus_type);
  	if (ret < 0) {
  		pr_err("could not register bus type\n");
  		goto error_nothing;
  	}
  
  	ret = alloc_chrdev_region(&iio_devt, 0, IIO_DEV_MAX, "iio");
  	if (ret < 0) {
  		pr_err("failed to allocate char dev region\n");
  		goto error_unregister_bus_type;
  	}
  
  	iio_debugfs_dentry = debugfs_create_dir("iio", NULL);
  
  	return 0;
  
  error_unregister_bus_type:
  	bus_unregister(&iio_bus_type);
  error_nothing:
  	return ret;
  }
  
  static void __exit iio_exit(void)
  {
  	if (iio_devt)
  		unregister_chrdev_region(iio_devt, IIO_DEV_MAX);
  	bus_unregister(&iio_bus_type);
  	debugfs_remove(iio_debugfs_dentry);
  }
  
  #if defined(CONFIG_DEBUG_FS)
  static ssize_t iio_debugfs_read_reg(struct file *file, char __user *userbuf,
  			      size_t count, loff_t *ppos)
  {
  	struct iio_dev *indio_dev = file->private_data;
  	char buf[20];
  	unsigned val = 0;
  	ssize_t len;
  	int ret;
  
  	ret = indio_dev->info->debugfs_reg_access(indio_dev,
  						  indio_dev->cached_reg_addr,
  						  0, &val);
  	if (ret)
  		dev_err(indio_dev->dev.parent, "%s: read failed\n", __func__);
  
  	len = snprintf(buf, sizeof(buf), "0x%X\n", val);
  
  	return simple_read_from_buffer(userbuf, count, ppos, buf, len);
  }
  
  static ssize_t iio_debugfs_write_reg(struct file *file,
  		     const char __user *userbuf, size_t count, loff_t *ppos)
  {
  	struct iio_dev *indio_dev = file->private_data;
  	unsigned reg, val;
  	char buf[80];
  	int ret;
  
  	count = min_t(size_t, count, (sizeof(buf)-1));
  	if (copy_from_user(buf, userbuf, count))
  		return -EFAULT;
  
  	buf[count] = 0;
  
  	ret = sscanf(buf, "%i %i", &reg, &val);
  
  	switch (ret) {
  	case 1:
  		indio_dev->cached_reg_addr = reg;
  		break;
  	case 2:
  		indio_dev->cached_reg_addr = reg;
  		ret = indio_dev->info->debugfs_reg_access(indio_dev, reg,
  							  val, NULL);
  		if (ret) {
  			dev_err(indio_dev->dev.parent, "%s: write failed\n",
  				__func__);
  			return ret;
  		}
  		break;
  	default:
  		return -EINVAL;
  	}
  
  	return count;
  }
  
  static const struct file_operations iio_debugfs_reg_fops = {
  	.open = simple_open,
  	.read = iio_debugfs_read_reg,
  	.write = iio_debugfs_write_reg,
  };
  
  static void iio_device_unregister_debugfs(struct iio_dev *indio_dev)
  {
  	debugfs_remove_recursive(indio_dev->debugfs_dentry);
  }
  
  static int iio_device_register_debugfs(struct iio_dev *indio_dev)
  {
  	struct dentry *d;
  
  	if (indio_dev->info->debugfs_reg_access == NULL)
  		return 0;
  
  	if (!iio_debugfs_dentry)
  		return 0;
  
  	indio_dev->debugfs_dentry =
  		debugfs_create_dir(dev_name(&indio_dev->dev),
  				   iio_debugfs_dentry);
  	if (indio_dev->debugfs_dentry == NULL) {
  		dev_warn(indio_dev->dev.parent,
  			 "Failed to create debugfs directory\n");
  		return -EFAULT;
  	}
  
  	d = debugfs_create_file("direct_reg_access", 0644,
  				indio_dev->debugfs_dentry,
  				indio_dev, &iio_debugfs_reg_fops);
  	if (!d) {
  		iio_device_unregister_debugfs(indio_dev);
  		return -ENOMEM;
  	}
  
  	return 0;
  }
  #else
  static int iio_device_register_debugfs(struct iio_dev *indio_dev)
  {
  	return 0;
  }
  
  static void iio_device_unregister_debugfs(struct iio_dev *indio_dev)
  {
  }
  #endif /* CONFIG_DEBUG_FS */
  
  static ssize_t iio_read_channel_ext_info(struct device *dev,
  				     struct device_attribute *attr,
  				     char *buf)
  {
  	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
  	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
  	const struct iio_chan_spec_ext_info *ext_info;
  
  	ext_info = &this_attr->c->ext_info[this_attr->address];
  
  	return ext_info->read(indio_dev, ext_info->private, this_attr->c, buf);
  }
  
  static ssize_t iio_write_channel_ext_info(struct device *dev,
  				     struct device_attribute *attr,
  				     const char *buf,
  					 size_t len)
  {
  	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
  	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
  	const struct iio_chan_spec_ext_info *ext_info;
  
  	ext_info = &this_attr->c->ext_info[this_attr->address];
  
  	return ext_info->write(indio_dev, ext_info->private,
  			       this_attr->c, buf, len);
  }
  
  ssize_t iio_enum_available_read(struct iio_dev *indio_dev,
  	uintptr_t priv, const struct iio_chan_spec *chan, char *buf)
  {
  	const struct iio_enum *e = (const struct iio_enum *)priv;
  	unsigned int i;
  	size_t len = 0;
  
  	if (!e->num_items)
  		return 0;
  
  	for (i = 0; i < e->num_items; ++i)
  		len += scnprintf(buf + len, PAGE_SIZE - len, "%s ", e->items[i]);
  
  	/* replace last space with a newline */
  	buf[len - 1] = '\n';
  
  	return len;
  }
  EXPORT_SYMBOL_GPL(iio_enum_available_read);
  
  ssize_t iio_enum_read(struct iio_dev *indio_dev,
  	uintptr_t priv, const struct iio_chan_spec *chan, char *buf)
  {
  	const struct iio_enum *e = (const struct iio_enum *)priv;
  	int i;
  
  	if (!e->get)
  		return -EINVAL;
  
  	i = e->get(indio_dev, chan);
  	if (i < 0)
  		return i;
  	else if (i >= e->num_items)
  		return -EINVAL;
  
  	return snprintf(buf, PAGE_SIZE, "%s\n", e->items[i]);
  }
  EXPORT_SYMBOL_GPL(iio_enum_read);
  
  ssize_t iio_enum_write(struct iio_dev *indio_dev,
  	uintptr_t priv, const struct iio_chan_spec *chan, const char *buf,
  	size_t len)
  {
  	const struct iio_enum *e = (const struct iio_enum *)priv;
  	unsigned int i;
  	int ret;
  
  	if (!e->set)
  		return -EINVAL;
  
  	for (i = 0; i < e->num_items; i++) {
  		if (sysfs_streq(buf, e->items[i]))
  			break;
  	}
  
  	if (i == e->num_items)
  		return -EINVAL;
  
  	ret = e->set(indio_dev, chan, i);
  	return ret ? ret : len;
  }
  EXPORT_SYMBOL_GPL(iio_enum_write);
  
  static const struct iio_mount_matrix iio_mount_idmatrix = {
  	.rotation = {
  		"1", "0", "0",
  		"0", "1", "0",
  		"0", "0", "1"
  	}
  };
  
  static int iio_setup_mount_idmatrix(const struct device *dev,
  				    struct iio_mount_matrix *matrix)
  {
  	*matrix = iio_mount_idmatrix;
  	dev_info(dev, "mounting matrix not found: using identity...\n");
  	return 0;
  }
  
  ssize_t iio_show_mount_matrix(struct iio_dev *indio_dev, uintptr_t priv,
  			      const struct iio_chan_spec *chan, char *buf)
  {
  	const struct iio_mount_matrix *mtx = ((iio_get_mount_matrix_t *)
  					      priv)(indio_dev, chan);
  
  	if (IS_ERR(mtx))
  		return PTR_ERR(mtx);
  
  	if (!mtx)
  		mtx = &iio_mount_idmatrix;
  
  	return snprintf(buf, PAGE_SIZE, "%s, %s, %s; %s, %s, %s; %s, %s, %s\n",
  			mtx->rotation[0], mtx->rotation[1], mtx->rotation[2],
  			mtx->rotation[3], mtx->rotation[4], mtx->rotation[5],
  			mtx->rotation[6], mtx->rotation[7], mtx->rotation[8]);
  }
  EXPORT_SYMBOL_GPL(iio_show_mount_matrix);
  
  /**
   * of_iio_read_mount_matrix() - retrieve iio device mounting matrix from
   *                              device-tree "mount-matrix" property
   * @dev:	device the mounting matrix property is assigned to
   * @propname:	device specific mounting matrix property name
   * @matrix:	where to store retrieved matrix
   *
   * If device is assigned no mounting matrix property, a default 3x3 identity
   * matrix will be filled in.
   *
   * Return: 0 if success, or a negative error code on failure.
   */
  #ifdef CONFIG_OF
  int of_iio_read_mount_matrix(const struct device *dev,
  			     const char *propname,
  			     struct iio_mount_matrix *matrix)
  {
  	if (dev->of_node) {
  		int err = of_property_read_string_array(dev->of_node,
  				propname, matrix->rotation,
  				ARRAY_SIZE(iio_mount_idmatrix.rotation));
  
  		if (err == ARRAY_SIZE(iio_mount_idmatrix.rotation))
  			return 0;
  
  		if (err >= 0)
  			/* Invalid number of matrix entries. */
  			return -EINVAL;
  
  		if (err != -EINVAL)
  			/* Invalid matrix declaration format. */
  			return err;
  	}
  
  	/* Matrix was not declared at all: fallback to identity. */
  	return iio_setup_mount_idmatrix(dev, matrix);
  }
  #else
  int of_iio_read_mount_matrix(const struct device *dev,
  			     const char *propname,
  			     struct iio_mount_matrix *matrix)
  {
  	return iio_setup_mount_idmatrix(dev, matrix);
  }
  #endif
  EXPORT_SYMBOL(of_iio_read_mount_matrix);
  
  static ssize_t __iio_format_value(char *buf, size_t len, unsigned int type,
  				  int size, const int *vals)
  {
  	unsigned long long tmp;
  	int tmp0, tmp1;
  	bool scale_db = false;
  
  	switch (type) {
  	case IIO_VAL_INT:
  		return snprintf(buf, len, "%d", vals[0]);
  	case IIO_VAL_INT_PLUS_MICRO_DB:
  		scale_db = true;
  	case IIO_VAL_INT_PLUS_MICRO:
  		if (vals[1] < 0)
  			return snprintf(buf, len, "-%d.%06u%s", abs(vals[0]),
  					-vals[1], scale_db ? " dB" : "");
  		else
  			return snprintf(buf, len, "%d.%06u%s", vals[0], vals[1],
  					scale_db ? " dB" : "");
  	case IIO_VAL_INT_PLUS_NANO:
  		if (vals[1] < 0)
  			return snprintf(buf, len, "-%d.%09u", abs(vals[0]),
  					-vals[1]);
  		else
  			return snprintf(buf, len, "%d.%09u", vals[0], vals[1]);
  	case IIO_VAL_FRACTIONAL:
  		tmp = div_s64((s64)vals[0] * 1000000000LL, vals[1]);
  		tmp1 = vals[1];
  		tmp0 = (int)div_s64_rem(tmp, 1000000000, &tmp1);
  		return snprintf(buf, len, "%d.%09u", tmp0, abs(tmp1));
  	case IIO_VAL_FRACTIONAL_LOG2:
  		tmp = (s64)vals[0] * 1000000000LL >> vals[1];
  		tmp1 = do_div(tmp, 1000000000LL);
  		tmp0 = tmp;
  		return snprintf(buf, len, "%d.%09u", tmp0, tmp1);
  	case IIO_VAL_INT_MULTIPLE:
  	{
  		int i;
  		int l = 0;
  
  		for (i = 0; i < size; ++i) {
  			l += snprintf(&buf[l], len - l, "%d ", vals[i]);
  			if (l >= len)
  				break;
  		}
  		return l;
  	}
  	default:
  		return 0;
  	}
  }
  
  /**
   * iio_format_value() - Formats a IIO value into its string representation
   * @buf:	The buffer to which the formatted value gets written
   *		which is assumed to be big enough (i.e. PAGE_SIZE).
   * @type:	One of the IIO_VAL_... constants. This decides how the val
   *		and val2 parameters are formatted.
   * @size:	Number of IIO value entries contained in vals
   * @vals:	Pointer to the values, exact meaning depends on the
   *		type parameter.
   *
   * Return: 0 by default, a negative number on failure or the
   *	   total number of characters written for a type that belongs
   *	   to the IIO_VAL_... constant.
   */
  ssize_t iio_format_value(char *buf, unsigned int type, int size, int *vals)
  {
  	ssize_t len;
  
  	len = __iio_format_value(buf, PAGE_SIZE, type, size, vals);
  	if (len >= PAGE_SIZE - 1)
  		return -EFBIG;
  
  	return len + sprintf(buf + len, "\n");
  }
  EXPORT_SYMBOL_GPL(iio_format_value);
  
  static ssize_t iio_read_channel_info(struct device *dev,
  				     struct device_attribute *attr,
  				     char *buf)
  {
  	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
  	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
  	int vals[INDIO_MAX_RAW_ELEMENTS];
  	int ret;
  	int val_len = 2;
  
  	if (indio_dev->info->read_raw_multi)
  		ret = indio_dev->info->read_raw_multi(indio_dev, this_attr->c,
  							INDIO_MAX_RAW_ELEMENTS,
  							vals, &val_len,
  							this_attr->address);
  	else
  		ret = indio_dev->info->read_raw(indio_dev, this_attr->c,
  				    &vals[0], &vals[1], this_attr->address);
  
  	if (ret < 0)
  		return ret;
  
  	return iio_format_value(buf, ret, val_len, vals);
  }
  
  static ssize_t iio_format_avail_list(char *buf, const int *vals,
  				     int type, int length)
  {
  	int i;
  	ssize_t len = 0;
  
  	switch (type) {
  	case IIO_VAL_INT:
  		for (i = 0; i < length; i++) {
  			len += __iio_format_value(buf + len, PAGE_SIZE - len,
  						  type, 1, &vals[i]);
  			if (len >= PAGE_SIZE)
  				return -EFBIG;
  			if (i < length - 1)
  				len += snprintf(buf + len, PAGE_SIZE - len,
  						" ");
  			else
  				len += snprintf(buf + len, PAGE_SIZE - len,
  						"\n");
  			if (len >= PAGE_SIZE)
  				return -EFBIG;
  		}
  		break;
  	default:
  		for (i = 0; i < length / 2; i++) {
  			len += __iio_format_value(buf + len, PAGE_SIZE - len,
  						  type, 2, &vals[i * 2]);
  			if (len >= PAGE_SIZE)
  				return -EFBIG;
  			if (i < length / 2 - 1)
  				len += snprintf(buf + len, PAGE_SIZE - len,
  						" ");
  			else
  				len += snprintf(buf + len, PAGE_SIZE - len,
  						"\n");
  			if (len >= PAGE_SIZE)
  				return -EFBIG;
  		}
  	}
  
  	return len;
  }
  
  static ssize_t iio_format_avail_range(char *buf, const int *vals, int type)
  {
  	int i;
  	ssize_t len;
  
  	len = snprintf(buf, PAGE_SIZE, "[");
  	switch (type) {
  	case IIO_VAL_INT:
  		for (i = 0; i < 3; i++) {
  			len += __iio_format_value(buf + len, PAGE_SIZE - len,
  						  type, 1, &vals[i]);
  			if (len >= PAGE_SIZE)
  				return -EFBIG;
  			if (i < 2)
  				len += snprintf(buf + len, PAGE_SIZE - len,
  						" ");
  			else
  				len += snprintf(buf + len, PAGE_SIZE - len,
  						"]\n");
  			if (len >= PAGE_SIZE)
  				return -EFBIG;
  		}
  		break;
  	default:
  		for (i = 0; i < 3; i++) {
  			len += __iio_format_value(buf + len, PAGE_SIZE - len,
  						  type, 2, &vals[i * 2]);
  			if (len >= PAGE_SIZE)
  				return -EFBIG;
  			if (i < 2)
  				len += snprintf(buf + len, PAGE_SIZE - len,
  						" ");
  			else
  				len += snprintf(buf + len, PAGE_SIZE - len,
  						"]\n");
  			if (len >= PAGE_SIZE)
  				return -EFBIG;
  		}
  	}
  
  	return len;
  }
  
  static ssize_t iio_read_channel_info_avail(struct device *dev,
  					   struct device_attribute *attr,
  					   char *buf)
  {
  	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
  	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
  	const int *vals;
  	int ret;
  	int length;
  	int type;
  
  	ret = indio_dev->info->read_avail(indio_dev, this_attr->c,
  					  &vals, &type, &length,
  					  this_attr->address);
  
  	if (ret < 0)
  		return ret;
  	switch (ret) {
  	case IIO_AVAIL_LIST:
  		return iio_format_avail_list(buf, vals, type, length);
  	case IIO_AVAIL_RANGE:
  		return iio_format_avail_range(buf, vals, type);
  	default:
  		return -EINVAL;
  	}
  }
  
  /**
   * iio_str_to_fixpoint() - Parse a fixed-point number from a string
   * @str: The string to parse
   * @fract_mult: Multiplier for the first decimal place, should be a power of 10
   * @integer: The integer part of the number
   * @fract: The fractional part of the number
   *
   * Returns 0 on success, or a negative error code if the string could not be
   * parsed.
   */
  int iio_str_to_fixpoint(const char *str, int fract_mult,
  	int *integer, int *fract)
  {
  	int i = 0, f = 0;
  	bool integer_part = true, negative = false;
  
  	if (fract_mult == 0) {
  		*fract = 0;
  
  		return kstrtoint(str, 0, integer);
  	}
  
  	if (str[0] == '-') {
  		negative = true;
  		str++;
  	} else if (str[0] == '+') {
  		str++;
  	}
  
  	while (*str) {
  		if ('0' <= *str && *str <= '9') {
  			if (integer_part) {
  				i = i * 10 + *str - '0';
  			} else {
  				f += fract_mult * (*str - '0');
  				fract_mult /= 10;
  			}
  		} else if (*str == '\n') {
  			if (*(str + 1) == '\0')
  				break;
  			else
  				return -EINVAL;
  		} else if (*str == '.' && integer_part) {
  			integer_part = false;
  		} else {
  			return -EINVAL;
  		}
  		str++;
  	}
  
  	if (negative) {
  		if (i)
  			i = -i;
  		else
  			f = -f;
  	}
  
  	*integer = i;
  	*fract = f;
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(iio_str_to_fixpoint);
  
  static ssize_t iio_write_channel_info(struct device *dev,
  				      struct device_attribute *attr,
  				      const char *buf,
  				      size_t len)
  {
  	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
  	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
  	int ret, fract_mult = 100000;
  	int integer, fract;
  
  	/* Assumes decimal - precision based on number of digits */
  	if (!indio_dev->info->write_raw)
  		return -EINVAL;
  
  	if (indio_dev->info->write_raw_get_fmt)
  		switch (indio_dev->info->write_raw_get_fmt(indio_dev,
  			this_attr->c, this_attr->address)) {
  		case IIO_VAL_INT:
  			fract_mult = 0;
  			break;
  		case IIO_VAL_INT_PLUS_MICRO:
  			fract_mult = 100000;
  			break;
  		case IIO_VAL_INT_PLUS_NANO:
  			fract_mult = 100000000;
  			break;
  		default:
  			return -EINVAL;
  		}
  
  	ret = iio_str_to_fixpoint(buf, fract_mult, &integer, &fract);
  	if (ret)
  		return ret;
  
  	ret = indio_dev->info->write_raw(indio_dev, this_attr->c,
  					 integer, fract, this_attr->address);
  	if (ret)
  		return ret;
  
  	return len;
  }
  
  static
  int __iio_device_attr_init(struct device_attribute *dev_attr,
  			   const char *postfix,
  			   struct iio_chan_spec const *chan,
  			   ssize_t (*readfunc)(struct device *dev,
  					       struct device_attribute *attr,
  					       char *buf),
  			   ssize_t (*writefunc)(struct device *dev,
  						struct device_attribute *attr,
  						const char *buf,
  						size_t len),
  			   enum iio_shared_by shared_by)
  {
  	int ret = 0;
  	char *name = NULL;
  	char *full_postfix;
  	sysfs_attr_init(&dev_attr->attr);
  
  	/* Build up postfix of <extend_name>_<modifier>_postfix */
  	if (chan->modified && (shared_by == IIO_SEPARATE)) {
  		if (chan->extend_name)
  			full_postfix = kasprintf(GFP_KERNEL, "%s_%s_%s",
  						 iio_modifier_names[chan
  								    ->channel2],
  						 chan->extend_name,
  						 postfix);
  		else
  			full_postfix = kasprintf(GFP_KERNEL, "%s_%s",
  						 iio_modifier_names[chan
  								    ->channel2],
  						 postfix);
  	} else {
  		if (chan->extend_name == NULL || shared_by != IIO_SEPARATE)
  			full_postfix = kstrdup(postfix, GFP_KERNEL);
  		else
  			full_postfix = kasprintf(GFP_KERNEL,
  						 "%s_%s",
  						 chan->extend_name,
  						 postfix);
  	}
  	if (full_postfix == NULL)
  		return -ENOMEM;
  
  	if (chan->differential) { /* Differential can not have modifier */
  		switch (shared_by) {
  		case IIO_SHARED_BY_ALL:
  			name = kasprintf(GFP_KERNEL, "%s", full_postfix);
  			break;
  		case IIO_SHARED_BY_DIR:
  			name = kasprintf(GFP_KERNEL, "%s_%s",
  						iio_direction[chan->output],
  						full_postfix);
  			break;
  		case IIO_SHARED_BY_TYPE:
  			name = kasprintf(GFP_KERNEL, "%s_%s-%s_%s",
  					    iio_direction[chan->output],
  					    iio_chan_type_name_spec[chan->type],
  					    iio_chan_type_name_spec[chan->type],
  					    full_postfix);
  			break;
  		case IIO_SEPARATE:
  			if (!chan->indexed) {
  				WARN(1, "Differential channels must be indexed\n");
  				ret = -EINVAL;
  				goto error_free_full_postfix;
  			}
  			name = kasprintf(GFP_KERNEL,
  					    "%s_%s%d-%s%d_%s",
  					    iio_direction[chan->output],
  					    iio_chan_type_name_spec[chan->type],
  					    chan->channel,
  					    iio_chan_type_name_spec[chan->type],
  					    chan->channel2,
  					    full_postfix);
  			break;
  		}
  	} else { /* Single ended */
  		switch (shared_by) {
  		case IIO_SHARED_BY_ALL:
  			name = kasprintf(GFP_KERNEL, "%s", full_postfix);
  			break;
  		case IIO_SHARED_BY_DIR:
  			name = kasprintf(GFP_KERNEL, "%s_%s",
  						iio_direction[chan->output],
  						full_postfix);
  			break;
  		case IIO_SHARED_BY_TYPE:
  			name = kasprintf(GFP_KERNEL, "%s_%s_%s",
  					    iio_direction[chan->output],
  					    iio_chan_type_name_spec[chan->type],
  					    full_postfix);
  			break;
  
  		case IIO_SEPARATE:
  			if (chan->indexed)
  				name = kasprintf(GFP_KERNEL, "%s_%s%d_%s",
  						    iio_direction[chan->output],
  						    iio_chan_type_name_spec[chan->type],
  						    chan->channel,
  						    full_postfix);
  			else
  				name = kasprintf(GFP_KERNEL, "%s_%s_%s",
  						    iio_direction[chan->output],
  						    iio_chan_type_name_spec[chan->type],
  						    full_postfix);
  			break;
  		}
  	}
  	if (name == NULL) {
  		ret = -ENOMEM;
  		goto error_free_full_postfix;
  	}
  	dev_attr->attr.name = name;
  
  	if (readfunc) {
  		dev_attr->attr.mode |= S_IRUGO;
  		dev_attr->show = readfunc;
  	}
  
  	if (writefunc) {
  		dev_attr->attr.mode |= S_IWUSR;
  		dev_attr->store = writefunc;
  	}
  
  error_free_full_postfix:
  	kfree(full_postfix);
  
  	return ret;
  }
  
  static void __iio_device_attr_deinit(struct device_attribute *dev_attr)
  {
  	kfree(dev_attr->attr.name);
  }
  
  int __iio_add_chan_devattr(const char *postfix,
  			   struct iio_chan_spec const *chan,
  			   ssize_t (*readfunc)(struct device *dev,
  					       struct device_attribute *attr,
  					       char *buf),
  			   ssize_t (*writefunc)(struct device *dev,
  						struct device_attribute *attr,
  						const char *buf,
  						size_t len),
  			   u64 mask,
  			   enum iio_shared_by shared_by,
  			   struct device *dev,
  			   struct list_head *attr_list)
  {
  	int ret;
  	struct iio_dev_attr *iio_attr, *t;
  
  	iio_attr = kzalloc(sizeof(*iio_attr), GFP_KERNEL);
  	if (iio_attr == NULL)
  		return -ENOMEM;
  	ret = __iio_device_attr_init(&iio_attr->dev_attr,
  				     postfix, chan,
  				     readfunc, writefunc, shared_by);
  	if (ret)
  		goto error_iio_dev_attr_free;
  	iio_attr->c = chan;
  	iio_attr->address = mask;
  	list_for_each_entry(t, attr_list, l)
  		if (strcmp(t->dev_attr.attr.name,
  			   iio_attr->dev_attr.attr.name) == 0) {
  			if (shared_by == IIO_SEPARATE)
  				dev_err(dev, "tried to double register : %s\n",
  					t->dev_attr.attr.name);
  			ret = -EBUSY;
  			goto error_device_attr_deinit;
  		}
  	list_add(&iio_attr->l, attr_list);
  
  	return 0;
  
  error_device_attr_deinit:
  	__iio_device_attr_deinit(&iio_attr->dev_attr);
  error_iio_dev_attr_free:
  	kfree(iio_attr);
  	return ret;
  }
  
  static int iio_device_add_info_mask_type(struct iio_dev *indio_dev,
  					 struct iio_chan_spec const *chan,
  					 enum iio_shared_by shared_by,
  					 const long *infomask)
  {
  	int i, ret, attrcount = 0;
  
  	for_each_set_bit(i, infomask, sizeof(infomask)*8) {
  		if (i >= ARRAY_SIZE(iio_chan_info_postfix))
  			return -EINVAL;
  		ret = __iio_add_chan_devattr(iio_chan_info_postfix[i],
  					     chan,
  					     &iio_read_channel_info,
  					     &iio_write_channel_info,
  					     i,
  					     shared_by,
  					     &indio_dev->dev,
  					     &indio_dev->channel_attr_list);
  		if ((ret == -EBUSY) && (shared_by != IIO_SEPARATE))
  			continue;
  		else if (ret < 0)
  			return ret;
  		attrcount++;
  	}
  
  	return attrcount;
  }
  
  static int iio_device_add_info_mask_type_avail(struct iio_dev *indio_dev,
  					       struct iio_chan_spec const *chan,
  					       enum iio_shared_by shared_by,
  					       const long *infomask)
  {
  	int i, ret, attrcount = 0;
  	char *avail_postfix;
  
  	for_each_set_bit(i, infomask, sizeof(infomask) * 8) {
  		avail_postfix = kasprintf(GFP_KERNEL,
  					  "%s_available",
  					  iio_chan_info_postfix[i]);
  		if (!avail_postfix)
  			return -ENOMEM;
  
  		ret = __iio_add_chan_devattr(avail_postfix,
  					     chan,
  					     &iio_read_channel_info_avail,
  					     NULL,
  					     i,
  					     shared_by,
  					     &indio_dev->dev,
  					     &indio_dev->channel_attr_list);
  		kfree(avail_postfix);
  		if ((ret == -EBUSY) && (shared_by != IIO_SEPARATE))
  			continue;
  		else if (ret < 0)
  			return ret;
  		attrcount++;
  	}
  
  	return attrcount;
  }
  
  static int iio_device_add_channel_sysfs(struct iio_dev *indio_dev,
  					struct iio_chan_spec const *chan)
  {
  	int ret, attrcount = 0;
  	const struct iio_chan_spec_ext_info *ext_info;
  
  	if (chan->channel < 0)
  		return 0;
  	ret = iio_device_add_info_mask_type(indio_dev, chan,
  					    IIO_SEPARATE,
  					    &chan->info_mask_separate);
  	if (ret < 0)
  		return ret;
  	attrcount += ret;
  
  	ret = iio_device_add_info_mask_type_avail(indio_dev, chan,
  						  IIO_SEPARATE,
  						  &chan->
  						  info_mask_separate_available);
  	if (ret < 0)
  		return ret;
  	attrcount += ret;
  
  	ret = iio_device_add_info_mask_type(indio_dev, chan,
  					    IIO_SHARED_BY_TYPE,
  					    &chan->info_mask_shared_by_type);
  	if (ret < 0)
  		return ret;
  	attrcount += ret;
  
  	ret = iio_device_add_info_mask_type_avail(indio_dev, chan,
  						  IIO_SHARED_BY_TYPE,
  						  &chan->
  						  info_mask_shared_by_type_available);
  	if (ret < 0)
  		return ret;
  	attrcount += ret;
  
  	ret = iio_device_add_info_mask_type(indio_dev, chan,
  					    IIO_SHARED_BY_DIR,
  					    &chan->info_mask_shared_by_dir);
  	if (ret < 0)
  		return ret;
  	attrcount += ret;
  
  	ret = iio_device_add_info_mask_type_avail(indio_dev, chan,
  						  IIO_SHARED_BY_DIR,
  						  &chan->info_mask_shared_by_dir_available);
  	if (ret < 0)
  		return ret;
  	attrcount += ret;
  
  	ret = iio_device_add_info_mask_type(indio_dev, chan,
  					    IIO_SHARED_BY_ALL,
  					    &chan->info_mask_shared_by_all);
  	if (ret < 0)
  		return ret;
  	attrcount += ret;
  
  	ret = iio_device_add_info_mask_type_avail(indio_dev, chan,
  						  IIO_SHARED_BY_ALL,
  						  &chan->info_mask_shared_by_all_available);
  	if (ret < 0)
  		return ret;
  	attrcount += ret;
  
  	if (chan->ext_info) {
  		unsigned int i = 0;
  		for (ext_info = chan->ext_info; ext_info->name; ext_info++) {
  			ret = __iio_add_chan_devattr(ext_info->name,
  					chan,
  					ext_info->read ?
  					    &iio_read_channel_ext_info : NULL,
  					ext_info->write ?
  					    &iio_write_channel_ext_info : NULL,
  					i,
  					ext_info->shared,
  					&indio_dev->dev,
  					&indio_dev->channel_attr_list);
  			i++;
  			if (ret == -EBUSY && ext_info->shared)
  				continue;
  
  			if (ret)
  				return ret;
  
  			attrcount++;
  		}
  	}
  
  	return attrcount;
  }
  
  /**
   * iio_free_chan_devattr_list() - Free a list of IIO device attributes
   * @attr_list: List of IIO device attributes
   *
   * This function frees the memory allocated for each of the IIO device
   * attributes in the list.
   */
  void iio_free_chan_devattr_list(struct list_head *attr_list)
  {
  	struct iio_dev_attr *p, *n;
  
  	list_for_each_entry_safe(p, n, attr_list, l) {
  		kfree(p->dev_attr.attr.name);
  		list_del(&p->l);
  		kfree(p);
  	}
  }
  
  static ssize_t iio_show_dev_name(struct device *dev,
  				 struct device_attribute *attr,
  				 char *buf)
  {
  	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
  	return snprintf(buf, PAGE_SIZE, "%s\n", indio_dev->name);
  }
  
  static DEVICE_ATTR(name, S_IRUGO, iio_show_dev_name, NULL);
  
  static ssize_t iio_show_timestamp_clock(struct device *dev,
  					struct device_attribute *attr,
  					char *buf)
  {
  	const struct iio_dev *indio_dev = dev_to_iio_dev(dev);
  	const clockid_t clk = iio_device_get_clock(indio_dev);
  	const char *name;
  	ssize_t sz;
  
  	switch (clk) {
  	case CLOCK_REALTIME:
  		name = "realtime\n";
  		sz = sizeof("realtime\n");
  		break;
  	case CLOCK_MONOTONIC:
  		name = "monotonic\n";
  		sz = sizeof("monotonic\n");
  		break;
  	case CLOCK_MONOTONIC_RAW:
  		name = "monotonic_raw\n";
  		sz = sizeof("monotonic_raw\n");
  		break;
  	case CLOCK_REALTIME_COARSE:
  		name = "realtime_coarse\n";
  		sz = sizeof("realtime_coarse\n");
  		break;
  	case CLOCK_MONOTONIC_COARSE:
  		name = "monotonic_coarse\n";
  		sz = sizeof("monotonic_coarse\n");
  		break;
  	case CLOCK_BOOTTIME:
  		name = "boottime\n";
  		sz = sizeof("boottime\n");
  		break;
  	case CLOCK_TAI:
  		name = "tai\n";
  		sz = sizeof("tai\n");
  		break;
  	default:
  		BUG();
  	}
  
  	memcpy(buf, name, sz);
  	return sz;
  }
  
  static ssize_t iio_store_timestamp_clock(struct device *dev,
  					 struct device_attribute *attr,
  					 const char *buf, size_t len)
  {
  	clockid_t clk;
  	int ret;
  
  	if (sysfs_streq(buf, "realtime"))
  		clk = CLOCK_REALTIME;
  	else if (sysfs_streq(buf, "monotonic"))
  		clk = CLOCK_MONOTONIC;
  	else if (sysfs_streq(buf, "monotonic_raw"))
  		clk = CLOCK_MONOTONIC_RAW;
  	else if (sysfs_streq(buf, "realtime_coarse"))
  		clk = CLOCK_REALTIME_COARSE;
  	else if (sysfs_streq(buf, "monotonic_coarse"))
  		clk = CLOCK_MONOTONIC_COARSE;
  	else if (sysfs_streq(buf, "boottime"))
  		clk = CLOCK_BOOTTIME;
  	else if (sysfs_streq(buf, "tai"))
  		clk = CLOCK_TAI;
  	else
  		return -EINVAL;
  
  	ret = iio_device_set_clock(dev_to_iio_dev(dev), clk);
  	if (ret)
  		return ret;
  
  	return len;
  }
  
  static DEVICE_ATTR(current_timestamp_clock, S_IRUGO | S_IWUSR,
  		   iio_show_timestamp_clock, iio_store_timestamp_clock);
  
  static int iio_device_register_sysfs(struct iio_dev *indio_dev)
  {
  	int i, ret = 0, attrcount, attrn, attrcount_orig = 0;
  	struct iio_dev_attr *p;
  	struct attribute **attr, *clk = NULL;
  
  	/* First count elements in any existing group */
  	if (indio_dev->info->attrs) {
  		attr = indio_dev->info->attrs->attrs;
  		while (*attr++ != NULL)
  			attrcount_orig++;
  	}
  	attrcount = attrcount_orig;
  	/*
  	 * New channel registration method - relies on the fact a group does
  	 * not need to be initialized if its name is NULL.
  	 */
  	if (indio_dev->channels)
  		for (i = 0; i < indio_dev->num_channels; i++) {
  			const struct iio_chan_spec *chan =
  				&indio_dev->channels[i];
  
  			if (chan->type == IIO_TIMESTAMP)
  				clk = &dev_attr_current_timestamp_clock.attr;
  
  			ret = iio_device_add_channel_sysfs(indio_dev, chan);
  			if (ret < 0)
  				goto error_clear_attrs;
  			attrcount += ret;
  		}
  
  	if (indio_dev->event_interface)
  		clk = &dev_attr_current_timestamp_clock.attr;
  
  	if (indio_dev->name)
  		attrcount++;
  	if (clk)
  		attrcount++;
  
  	indio_dev->chan_attr_group.attrs = kcalloc(attrcount + 1,
  						   sizeof(indio_dev->chan_attr_group.attrs[0]),
  						   GFP_KERNEL);
  	if (indio_dev->chan_attr_group.attrs == NULL) {
  		ret = -ENOMEM;
  		goto error_clear_attrs;
  	}
  	/* Copy across original attributes */
  	if (indio_dev->info->attrs)
  		memcpy(indio_dev->chan_attr_group.attrs,
  		       indio_dev->info->attrs->attrs,
  		       sizeof(indio_dev->chan_attr_group.attrs[0])
  		       *attrcount_orig);
  	attrn = attrcount_orig;
  	/* Add all elements from the list. */
  	list_for_each_entry(p, &indio_dev->channel_attr_list, l)
  		indio_dev->chan_attr_group.attrs[attrn++] = &p->dev_attr.attr;
  	if (indio_dev->name)
  		indio_dev->chan_attr_group.attrs[attrn++] = &dev_attr_name.attr;
  	if (clk)
  		indio_dev->chan_attr_group.attrs[attrn++] = clk;
  
  	indio_dev->groups[indio_dev->groupcounter++] =
  		&indio_dev->chan_attr_group;
  
  	return 0;
  
  error_clear_attrs:
  	iio_free_chan_devattr_list(&indio_dev->channel_attr_list);
  
  	return ret;
  }
  
  static void iio_device_unregister_sysfs(struct iio_dev *indio_dev)
  {
  
  	iio_free_chan_devattr_list(&indio_dev->channel_attr_list);
  	kfree(indio_dev->chan_attr_group.attrs);
  	indio_dev->chan_attr_group.attrs = NULL;
  }
  
  static void iio_dev_release(struct device *device)
  {
  	struct iio_dev *indio_dev = dev_to_iio_dev(device);
  	if (indio_dev->modes & (INDIO_BUFFER_TRIGGERED | INDIO_EVENT_TRIGGERED))
  		iio_device_unregister_trigger_consumer(indio_dev);
  	iio_device_unregister_eventset(indio_dev);
  	iio_device_unregister_sysfs(indio_dev);
  
  	iio_buffer_put(indio_dev->buffer);
  
  	ida_simple_remove(&iio_ida, indio_dev->id);
  	kfree(indio_dev);
  }
  
  struct device_type iio_device_type = {
  	.name = "iio_device",
  	.release = iio_dev_release,
  };
  
  /**
   * iio_device_alloc() - allocate an iio_dev from a driver
   * @sizeof_priv:	Space to allocate for private structure.
   **/
  struct iio_dev *iio_device_alloc(int sizeof_priv)
  {
  	struct iio_dev *dev;
  	size_t alloc_size;
  
  	alloc_size = sizeof(struct iio_dev);
  	if (sizeof_priv) {
  		alloc_size = ALIGN(alloc_size, IIO_ALIGN);
  		alloc_size += sizeof_priv;
  	}
  	/* ensure 32-byte alignment of whole construct ? */
  	alloc_size += IIO_ALIGN - 1;
  
  	dev = kzalloc(alloc_size, GFP_KERNEL);
  
  	if (dev) {
  		dev->dev.groups = dev->groups;
  		dev->dev.type = &iio_device_type;
  		dev->dev.bus = &iio_bus_type;
  		device_initialize(&dev->dev);
  		dev_set_drvdata(&dev->dev, (void *)dev);
  		mutex_init(&dev->mlock);
  		mutex_init(&dev->info_exist_lock);
  		INIT_LIST_HEAD(&dev->channel_attr_list);
  
  		dev->id = ida_simple_get(&iio_ida, 0, 0, GFP_KERNEL);
  		if (dev->id < 0) {
  			/* cannot use a dev_err as the name isn't available */
  			pr_err("failed to get device id\n");
  			kfree(dev);
  			return NULL;
  		}
  		dev_set_name(&dev->dev, "iio:device%d", dev->id);
  		INIT_LIST_HEAD(&dev->buffer_list);
  	}
  
  	return dev;
  }
  EXPORT_SYMBOL(iio_device_alloc);
  
  /**
   * iio_device_free() - free an iio_dev from a driver
   * @dev:		the iio_dev associated with the device
   **/
  void iio_device_free(struct iio_dev *dev)
  {
  	if (dev)
  		put_device(&dev->dev);
  }
  EXPORT_SYMBOL(iio_device_free);
  
  static void devm_iio_device_release(struct device *dev, void *res)
  {
  	iio_device_free(*(struct iio_dev **)res);
  }
  
  int devm_iio_device_match(struct device *dev, void *res, void *data)
  {
  	struct iio_dev **r = res;
  	if (!r || !*r) {
  		WARN_ON(!r || !*r);
  		return 0;
  	}
  	return *r == data;
  }
  EXPORT_SYMBOL_GPL(devm_iio_device_match);
  
  /**
   * devm_iio_device_alloc - Resource-managed iio_device_alloc()
   * @dev:		Device to allocate iio_dev for
   * @sizeof_priv:	Space to allocate for private structure.
   *
   * Managed iio_device_alloc. iio_dev allocated with this function is
   * automatically freed on driver detach.
   *
   * If an iio_dev allocated with this function needs to be freed separately,
   * devm_iio_device_free() must be used.
   *
   * RETURNS:
   * Pointer to allocated iio_dev on success, NULL on failure.
   */
  struct iio_dev *devm_iio_device_alloc(struct device *dev, int sizeof_priv)
  {
  	struct iio_dev **ptr, *iio_dev;
  
  	ptr = devres_alloc(devm_iio_device_release, sizeof(*ptr),
  			   GFP_KERNEL);
  	if (!ptr)
  		return NULL;
  
  	iio_dev = iio_device_alloc(sizeof_priv);
  	if (iio_dev) {
  		*ptr = iio_dev;
  		devres_add(dev, ptr);
  	} else {
  		devres_free(ptr);
  	}
  
  	return iio_dev;
  }
  EXPORT_SYMBOL_GPL(devm_iio_device_alloc);
  
  /**
   * devm_iio_device_free - Resource-managed iio_device_free()
   * @dev:		Device this iio_dev belongs to
   * @iio_dev:		the iio_dev associated with the device
   *
   * Free iio_dev allocated with devm_iio_device_alloc().
   */
  void devm_iio_device_free(struct device *dev, struct iio_dev *iio_dev)
  {
  	int rc;
  
  	rc = devres_release(dev, devm_iio_device_release,
  			    devm_iio_device_match, iio_dev);
  	WARN_ON(rc);
  }
  EXPORT_SYMBOL_GPL(devm_iio_device_free);
  
  /**
   * iio_chrdev_open() - chrdev file open for buffer access and ioctls
   * @inode:	Inode structure for identifying the device in the file system
   * @filp:	File structure for iio device used to keep and later access
   *		private data
   *
   * Return: 0 on success or -EBUSY if the device is already opened
   **/
  static int iio_chrdev_open(struct inode *inode, struct file *filp)
  {
  	struct iio_dev *indio_dev = container_of(inode->i_cdev,
  						struct iio_dev, chrdev);
  
  	if (test_and_set_bit(IIO_BUSY_BIT_POS, &indio_dev->flags))
  		return -EBUSY;
  
  	iio_device_get(indio_dev);
  
  	filp->private_data = indio_dev;
  
  	return 0;
  }
  
  /**
   * iio_chrdev_release() - chrdev file close buffer access and ioctls
   * @inode:	Inode structure pointer for the char device
   * @filp:	File structure pointer for the char device
   *
   * Return: 0 for successful release
   */
  static int iio_chrdev_release(struct inode *inode, struct file *filp)
  {
  	struct iio_dev *indio_dev = container_of(inode->i_cdev,
  						struct iio_dev, chrdev);
  	clear_bit(IIO_BUSY_BIT_POS, &indio_dev->flags);
  	iio_device_put(indio_dev);
  
  	return 0;
  }
  
  /* Somewhat of a cross file organization violation - ioctls here are actually
   * event related */
  static long iio_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
  {
  	struct iio_dev *indio_dev = filp->private_data;
  	int __user *ip = (int __user *)arg;
  	int fd;
  
  	if (!indio_dev->info)
  		return -ENODEV;
  
  	if (cmd == IIO_GET_EVENT_FD_IOCTL) {
  		fd = iio_event_getfd(indio_dev);
  		if (fd < 0)
  			return fd;
  		if (copy_to_user(ip, &fd, sizeof(fd)))
  			return -EFAULT;
  		return 0;
  	}
  	return -EINVAL;
  }
  
  static const struct file_operations iio_buffer_fileops = {
  	.read = iio_buffer_read_first_n_outer_addr,
  	.release = iio_chrdev_release,
  	.open = iio_chrdev_open,
  	.poll = iio_buffer_poll_addr,
  	.owner = THIS_MODULE,
  	.llseek = noop_llseek,
  	.unlocked_ioctl = iio_ioctl,
  	.compat_ioctl = iio_ioctl,
  };
  
  static int iio_check_unique_scan_index(struct iio_dev *indio_dev)
  {
  	int i, j;
  	const struct iio_chan_spec *channels = indio_dev->channels;
  
  	if (!(indio_dev->modes & INDIO_ALL_BUFFER_MODES))
  		return 0;
  
  	for (i = 0; i < indio_dev->num_channels - 1; i++) {
  		if (channels[i].scan_index < 0)
  			continue;
  		for (j = i + 1; j < indio_dev->num_channels; j++)
  			if (channels[i].scan_index == channels[j].scan_index) {
  				dev_err(&indio_dev->dev,
  					"Duplicate scan index %d\n",
  					channels[i].scan_index);
  				return -EINVAL;
  			}
  	}
  
  	return 0;
  }
  
  static const struct iio_buffer_setup_ops noop_ring_setup_ops;
  
  /**
   * iio_device_register() - register a device with the IIO subsystem
   * @indio_dev:		Device structure filled by the device driver
   **/
  int iio_device_register(struct iio_dev *indio_dev)
  {
  	int ret;
  
  	/* If the calling driver did not initialize of_node, do it here */
  	if (!indio_dev->dev.of_node && indio_dev->dev.parent)
  		indio_dev->dev.of_node = indio_dev->dev.parent->of_node;
  
  	ret = iio_check_unique_scan_index(indio_dev);
  	if (ret < 0)
  		return ret;
  
  	/* configure elements for the chrdev */
  	indio_dev->dev.devt = MKDEV(MAJOR(iio_devt), indio_dev->id);
  
  	ret = iio_device_register_debugfs(indio_dev);
  	if (ret) {
  		dev_err(indio_dev->dev.parent,
  			"Failed to register debugfs interfaces\n");
  		return ret;
  	}
  
  	ret = iio_buffer_alloc_sysfs_and_mask(indio_dev);
  	if (ret) {
  		dev_err(indio_dev->dev.parent,
  			"Failed to create buffer sysfs interfaces\n");
  		goto error_unreg_debugfs;
  	}
  
  	ret = iio_device_register_sysfs(indio_dev);
  	if (ret) {
  		dev_err(indio_dev->dev.parent,
  			"Failed to register sysfs interfaces\n");
  		goto error_buffer_free_sysfs;
  	}
  	ret = iio_device_register_eventset(indio_dev);
  	if (ret) {
  		dev_err(indio_dev->dev.parent,
  			"Failed to register event set\n");
  		goto error_free_sysfs;
  	}
  	if (indio_dev->modes & (INDIO_BUFFER_TRIGGERED | INDIO_EVENT_TRIGGERED))
  		iio_device_register_trigger_consumer(indio_dev);
  
  	if ((indio_dev->modes & INDIO_ALL_BUFFER_MODES) &&
  		indio_dev->setup_ops == NULL)
  		indio_dev->setup_ops = &noop_ring_setup_ops;
  
  	cdev_init(&indio_dev->chrdev, &iio_buffer_fileops);
  	indio_dev->chrdev.owner = indio_dev->info->driver_module;
  	indio_dev->chrdev.kobj.parent = &indio_dev->dev.kobj;
  	ret = cdev_add(&indio_dev->chrdev, indio_dev->dev.devt, 1);
  	if (ret < 0)
  		goto error_unreg_eventset;
  
  	ret = device_add(&indio_dev->dev);
  	if (ret < 0)
  		goto error_cdev_del;
  
  	return 0;
  error_cdev_del:
  	cdev_del(&indio_dev->chrdev);
  error_unreg_eventset:
  	iio_device_unregister_eventset(indio_dev);
  error_free_sysfs:
  	iio_device_unregister_sysfs(indio_dev);
  error_buffer_free_sysfs:
  	iio_buffer_free_sysfs_and_mask(indio_dev);
  error_unreg_debugfs:
  	iio_device_unregister_debugfs(indio_dev);
  	return ret;
  }
  EXPORT_SYMBOL(iio_device_register);
  
  /**
   * iio_device_unregister() - unregister a device from the IIO subsystem
   * @indio_dev:		Device structure representing the device.
   **/
  void iio_device_unregister(struct iio_dev *indio_dev)
  {
  	mutex_lock(&indio_dev->info_exist_lock);
  
  	device_del(&indio_dev->dev);
  
  	if (indio_dev->chrdev.dev)
  		cdev_del(&indio_dev->chrdev);
  	iio_device_unregister_debugfs(indio_dev);
  
  	iio_disable_all_buffers(indio_dev);
  
  	indio_dev->info = NULL;
  
  	iio_device_wakeup_eventset(indio_dev);
  	iio_buffer_wakeup_poll(indio_dev);
  
  	mutex_unlock(&indio_dev->info_exist_lock);
  
  	iio_buffer_free_sysfs_and_mask(indio_dev);
  }
  EXPORT_SYMBOL(iio_device_unregister);
  
  static void devm_iio_device_unreg(struct device *dev, void *res)
  {
  	iio_device_unregister(*(struct iio_dev **)res);
  }
  
  /**
   * devm_iio_device_register - Resource-managed iio_device_register()
   * @dev:	Device to allocate iio_dev for
   * @indio_dev:	Device structure filled by the device driver
   *
   * Managed iio_device_register.  The IIO device registered with this
   * function is automatically unregistered on driver detach. This function
   * calls iio_device_register() internally. Refer to that function for more
   * information.
   *
   * If an iio_dev registered with this function needs to be unregistered
   * separately, devm_iio_device_unregister() must be used.
   *
   * RETURNS:
   * 0 on success, negative error number on failure.
   */
  int devm_iio_device_register(struct device *dev, struct iio_dev *indio_dev)
  {
  	struct iio_dev **ptr;
  	int ret;
  
  	ptr = devres_alloc(devm_iio_device_unreg, sizeof(*ptr), GFP_KERNEL);
  	if (!ptr)
  		return -ENOMEM;
  
  	*ptr = indio_dev;
  	ret = iio_device_register(indio_dev);
  	if (!ret)
  		devres_add(dev, ptr);
  	else
  		devres_free(ptr);
  
  	return ret;
  }
  EXPORT_SYMBOL_GPL(devm_iio_device_register);
  
  /**
   * devm_iio_device_unregister - Resource-managed iio_device_unregister()
   * @dev:	Device this iio_dev belongs to
   * @indio_dev:	the iio_dev associated with the device
   *
   * Unregister iio_dev registered with devm_iio_device_register().
   */
  void devm_iio_device_unregister(struct device *dev, struct iio_dev *indio_dev)
  {
  	int rc;
  
  	rc = devres_release(dev, devm_iio_device_unreg,
  			    devm_iio_device_match, indio_dev);
  	WARN_ON(rc);
  }
  EXPORT_SYMBOL_GPL(devm_iio_device_unregister);
  
  /**
   * iio_device_claim_direct_mode - Keep device in direct mode
   * @indio_dev:	the iio_dev associated with the device
   *
   * If the device is in direct mode it is guaranteed to stay
   * that way until iio_device_release_direct_mode() is called.
   *
   * Use with iio_device_release_direct_mode()
   *
   * Returns: 0 on success, -EBUSY on failure
   */
  int iio_device_claim_direct_mode(struct iio_dev *indio_dev)
  {
  	mutex_lock(&indio_dev->mlock);
  
  	if (iio_buffer_enabled(indio_dev)) {
  		mutex_unlock(&indio_dev->mlock);
  		return -EBUSY;
  	}
  	return 0;
  }
  EXPORT_SYMBOL_GPL(iio_device_claim_direct_mode);
  
  /**
   * iio_device_release_direct_mode - releases claim on direct mode
   * @indio_dev:	the iio_dev associated with the device
   *
   * Release the claim. Device is no longer guaranteed to stay
   * in direct mode.
   *
   * Use with iio_device_claim_direct_mode()
   */
  void iio_device_release_direct_mode(struct iio_dev *indio_dev)
  {
  	mutex_unlock(&indio_dev->mlock);
  }
  EXPORT_SYMBOL_GPL(iio_device_release_direct_mode);
  
  subsys_initcall(iio_init);
  module_exit(iio_exit);
  
  MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>");
  MODULE_DESCRIPTION("Industrial I/O core");
  MODULE_LICENSE("GPL");
  