/* 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/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>

/* 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",
};

static const char * const iio_modifier_names[] = {
        [IIO_MOD_X] = "x",
        [IIO_MOD_Y] = "y",
        [IIO_MOD_Z] = "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",
};

/* 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_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_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 __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 sprintf(buf, "%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);

/**
 * iio_format_value() - Formats a IIO value into its string representation
 * @buf: The buffer to which the formated value gets written
 * @type: One of the IIO_VAL_... constants. This decides how the val and val2
 *        parameters are formatted.
 * @val: First part of the value, exact meaning depends on the type parameter.
 * @val2: Second part of the value, exact meaning depends on the type parameter.
 */
ssize_t iio_format_value(char *buf, unsigned int type, int val, int val2)
{
        unsigned long long tmp;
        bool scale_db = false;

        switch (type) {
        case IIO_VAL_INT:
                return sprintf(buf, "%d\n", val);
        case IIO_VAL_INT_PLUS_MICRO_DB:
                scale_db = true;
        case IIO_VAL_INT_PLUS_MICRO:
                if (val2 < 0)
                        return sprintf(buf, "-%ld.%06u%s\n", abs(val), -val2,
                                scale_db ? " dB" : "");
                else
                        return sprintf(buf, "%d.%06u%s\n", val, val2,
                                scale_db ? " dB" : "");
        case IIO_VAL_INT_PLUS_NANO:
                if (val2 < 0)
                        return sprintf(buf, "-%ld.%09u\n", abs(val), -val2);
                else
                        return sprintf(buf, "%d.%09u\n", val, val2);
        case IIO_VAL_FRACTIONAL:
                tmp = div_s64((s64)val * 1000000000LL, val2);
                val2 = do_div(tmp, 1000000000LL);
                val = tmp;
                return sprintf(buf, "%d.%09u\n", val, val2);
        case IIO_VAL_FRACTIONAL_LOG2:
                tmp = (s64)val * 1000000000LL >> val2;
                val2 = do_div(tmp, 1000000000LL);
                val = tmp;
                return sprintf(buf, "%d.%09u\n", val, val2);
        default:
                return 0;
        }
}

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 val, val2;
        int ret = indio_dev->info->read_raw(indio_dev, this_attr->c,
                                            &val, &val2, this_attr->address);

        if (ret < 0)
                return ret;

        return iio_format_value(buf, ret, val, val2);
}

/**
 * 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 (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_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_ON("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) {
                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_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(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(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(indio_dev, chan,
                                            IIO_SHARED_BY_ALL,
                                            &chan->info_mask_shared_by_all);
        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. Note: if you want to reuse the list after calling
 * this function you have to reinitialize it using INIT_LIST_HEAD().
 */
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);
                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 sprintf(buf, "%s\n", indio_dev->name);
}

static DEVICE_ATTR(name, S_IRUGO, iio_show_dev_name, NULL);

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;

        /* 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++) {
                        ret = iio_device_add_channel_sysfs(indio_dev,
                                                           &indio_dev
                                                           ->channels[i]);
                        if (ret < 0)
                                goto error_clear_attrs;
                        attrcount += ret;
                }

        if (indio_dev->name)
                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;

        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);
}

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)
                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);
}

static 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;
}

/**
 * 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;

        /* use raw alloc_dr for kmalloc caller tracing */
        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
 **/
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
 **/
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 (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 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;

        /* 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_device_register_sysfs(indio_dev);
        if (ret) {
                dev_err(indio_dev->dev.parent,
                        "Failed to register sysfs interfaces\n");
                goto error_unreg_debugfs;
        }
        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)
                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_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);
}
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);

subsys_initcall(iio_init);
module_exit(iio_exit);

MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>");
MODULE_DESCRIPTION("Industrial I/O core");
MODULE_LICENSE("GPL");