// SPDX-License-Identifier: GPL-2.0-only
/* The industrial I/O core
 *
 * Copyright (c) 2008 Jonathan Cameron
 *
 * 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/property.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 <linux/iio/iio-opaque.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",
        [IIO_POSITIONRELATIVE]  = "positionrelative",
        [IIO_PHASE] = "phase",
        [IIO_MASSCONCENTRATION] = "massconcentration",
};

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_LIGHT_DUV] = "duv",
        [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",
        [IIO_MOD_PM1] = "pm1",
        [IIO_MOD_PM2P5] = "pm2p5",
        [IIO_MOD_PM4] = "pm4",
        [IIO_MOD_PM10] = "pm10",
        [IIO_MOD_ETHANOL] = "ethanol",
        [IIO_MOD_H2] = "h2",
        [IIO_MOD_O2] = "o2",
};

/* 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_HYSTERESIS_RELATIVE] = "hysteresis_relative",
        [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_CHAN_INFO_THERMOCOUPLE_TYPE] = "thermocouple_type",
        [IIO_CHAN_INFO_CALIBAMBIENT] = "calibambient",
};
/**
 * iio_device_id() - query the unique ID for the device
 * @indio_dev:          Device structure whose ID is being queried
 *
 * The IIO device ID is a unique index used for example for the naming
 * of the character device /dev/iio\:device[ID]
 */
int iio_device_id(struct iio_dev *indio_dev)
{
        struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);

        return iio_dev_opaque->id;
}
EXPORT_SYMBOL_GPL(iio_device_id);

/**
 * iio_sysfs_match_string_with_gaps - matches given string in an array with gaps
 * @array: array of strings
 * @n: number of strings in the array
 * @str: string to match with
 *
 * Returns index of @str in the @array or -EINVAL, similar to match_string().
 * Uses sysfs_streq instead of strcmp for matching.
 *
 * This routine will look for a string in an array of strings.
 * The search will continue until the element is found or the n-th element
 * is reached, regardless of any NULL elements in the array.
 */
static int iio_sysfs_match_string_with_gaps(const char * const *array, size_t n,
                                            const char *str)
{
        const char *item;
        int index;

        for (index = 0; index < n; index++) {
                item = array[index];
                if (!item)
                        continue;
                if (sysfs_streq(item, str))
                        return index;
        }

        return -EINVAL;
}

#if defined(CONFIG_DEBUG_FS)
/*
 * There's also a CONFIG_DEBUG_FS guard in include/linux/iio/iio.h for
 * iio_get_debugfs_dentry() to make it inline if CONFIG_DEBUG_FS is undefined
 */
struct dentry *iio_get_debugfs_dentry(struct iio_dev *indio_dev)
{
        struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
        return iio_dev_opaque->debugfs_dentry;
}
EXPORT_SYMBOL_GPL(iio_get_debugfs_dentry);
#endif

/**
 * 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 sysfs_emit(buf, "%s\n", to_iio_const_attr(attr)->string);
}
EXPORT_SYMBOL(iio_read_const_attr);

/**
 * iio_device_set_clock() - Set current timestamping clock for the device
 * @indio_dev: IIO device structure containing the device
 * @clock_id: timestamping clock posix identifier to set.
 */
int iio_device_set_clock(struct iio_dev *indio_dev, clockid_t clock_id)
{
        int ret;
        struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
        const struct iio_event_interface *ev_int = iio_dev_opaque->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;
        }
        iio_dev_opaque->clock_id = clock_id;
        mutex_unlock(&indio_dev->mlock);

        return 0;
}
EXPORT_SYMBOL(iio_device_set_clock);

/**
 * iio_device_get_clock() - Retrieve current timestamping clock for the device
 * @indio_dev: IIO device structure containing the device
 */
clockid_t iio_device_get_clock(const struct iio_dev *indio_dev)
{
        struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);

        return iio_dev_opaque->clock_id;
}
EXPORT_SYMBOL(iio_device_get_clock);

/**
 * 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 timespec64 tp;

        switch (iio_device_get_clock(indio_dev)) {
        case CLOCK_REALTIME:
                return ktime_get_real_ns();
        case CLOCK_MONOTONIC:
                return ktime_get_ns();
        case CLOCK_MONOTONIC_RAW:
                return ktime_get_raw_ns();
        case CLOCK_REALTIME_COARSE:
                return ktime_to_ns(ktime_get_coarse_real());
        case CLOCK_MONOTONIC_COARSE:
                ktime_get_coarse_ts64(&tp);
                return timespec64_to_ns(&tp);
        case CLOCK_BOOTTIME:
                return ktime_get_boottime_ns();
        case CLOCK_TAI:
                return ktime_get_clocktai_ns();
        default:
                BUG();
        }
}
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;
        struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
        unsigned val = 0;
        int ret;

        if (*ppos > 0)
                return simple_read_from_buffer(userbuf, count, ppos,
                                               iio_dev_opaque->read_buf,
                                               iio_dev_opaque->read_buf_len);

        ret = indio_dev->info->debugfs_reg_access(indio_dev,
                                                  iio_dev_opaque->cached_reg_addr,
                                                  0, &val);
        if (ret) {
                dev_err(indio_dev->dev.parent, "%s: read failed\n", __func__);
                return ret;
        }

        iio_dev_opaque->read_buf_len = snprintf(iio_dev_opaque->read_buf,
                                              sizeof(iio_dev_opaque->read_buf),
                                              "0x%X\n", val);

        return simple_read_from_buffer(userbuf, count, ppos,
                                       iio_dev_opaque->read_buf,
                                       iio_dev_opaque->read_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;
        struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
        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:
                iio_dev_opaque->cached_reg_addr = reg;
                break;
        case 2:
                iio_dev_opaque->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)
{
        struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
        debugfs_remove_recursive(iio_dev_opaque->debugfs_dentry);
}

static void iio_device_register_debugfs(struct iio_dev *indio_dev)
{
        struct iio_dev_opaque *iio_dev_opaque;

        if (indio_dev->info->debugfs_reg_access == NULL)
                return;

        if (!iio_debugfs_dentry)
                return;

        iio_dev_opaque = to_iio_dev_opaque(indio_dev);

        iio_dev_opaque->debugfs_dentry =
                debugfs_create_dir(dev_name(&indio_dev->dev),
                                   iio_debugfs_dentry);

        debugfs_create_file("direct_reg_access", 0644,
                            iio_dev_opaque->debugfs_dentry, indio_dev,
                            &iio_debugfs_reg_fops);
}
#else
static void iio_device_register_debugfs(struct iio_dev *indio_dev)
{
}

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) {
                if (!e->items[i])
                        continue;
                len += sysfs_emit_at(buf, 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 || !e->items[i])
                return -EINVAL;

        return sysfs_emit(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;
        int ret;

        if (!e->set)
                return -EINVAL;

        ret = iio_sysfs_match_string_with_gaps(e->items, e->num_items, buf);
        if (ret < 0)
                return ret;

        ret = e->set(indio_dev, chan, ret);
        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 sysfs_emit(buf, "%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);

/**
 * iio_read_mount_matrix() - retrieve iio device mounting matrix from
 *                           device "mount-matrix" property
 * @dev:        device the mounting matrix property is assigned to
 * @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.
 */
int iio_read_mount_matrix(struct device *dev, struct iio_mount_matrix *matrix)
{
        size_t len = ARRAY_SIZE(iio_mount_idmatrix.rotation);
        int err;

        err = device_property_read_string_array(dev, "mount-matrix", matrix->rotation, len);
        if (err == len)
                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);
}
EXPORT_SYMBOL(iio_read_mount_matrix);

static ssize_t __iio_format_value(char *buf, size_t offset, unsigned int type,
                                  int size, const int *vals)
{
        int tmp0, tmp1;
        s64 tmp2;
        bool scale_db = false;

        switch (type) {
        case IIO_VAL_INT:
                return sysfs_emit_at(buf, offset, "%d", vals[0]);
        case IIO_VAL_INT_PLUS_MICRO_DB:
                scale_db = true;
                fallthrough;
        case IIO_VAL_INT_PLUS_MICRO:
                if (vals[1] < 0)
                        return sysfs_emit_at(buf, offset, "-%d.%06u%s",
                                             abs(vals[0]), -vals[1],
                                             scale_db ? " dB" : "");
                else
                        return sysfs_emit_at(buf, offset, "%d.%06u%s", vals[0],
                                             vals[1], scale_db ? " dB" : "");
        case IIO_VAL_INT_PLUS_NANO:
                if (vals[1] < 0)
                        return sysfs_emit_at(buf, offset, "-%d.%09u",
                                             abs(vals[0]), -vals[1]);
                else
                        return sysfs_emit_at(buf, offset, "%d.%09u", vals[0],
                                             vals[1]);
        case IIO_VAL_FRACTIONAL:
                tmp2 = div_s64((s64)vals[0] * 1000000000LL, vals[1]);
                tmp1 = vals[1];
                tmp0 = (int)div_s64_rem(tmp2, 1000000000, &tmp1);
                if ((tmp2 < 0) && (tmp0 == 0))
                        return sysfs_emit_at(buf, offset, "-0.%09u", abs(tmp1));
                else
                        return sysfs_emit_at(buf, offset, "%d.%09u", tmp0,
                                             abs(tmp1));
        case IIO_VAL_FRACTIONAL_LOG2:
                tmp2 = shift_right((s64)vals[0] * 1000000000LL, vals[1]);
                tmp0 = (int)div_s64_rem(tmp2, 1000000000LL, &tmp1);
                if (tmp0 == 0 && tmp2 < 0)
                        return sysfs_emit_at(buf, offset, "-0.%09u", abs(tmp1));
                else
                        return sysfs_emit_at(buf, offset, "%d.%09u", tmp0,
                                             abs(tmp1));
        case IIO_VAL_INT_MULTIPLE:
        {
                int i;
                int l = 0;

                for (i = 0; i < size; ++i)
                        l += sysfs_emit_at(buf, offset + l, "%d ", vals[i]);
                return l;
        }
        case IIO_VAL_CHAR:
                return sysfs_emit_at(buf, offset, "%c", (char)vals[0]);
        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, 0, type, size, vals);
        if (len >= PAGE_SIZE - 1)
                return -EFBIG;

        return len + sysfs_emit_at(buf, len, "\n");
}
EXPORT_SYMBOL_GPL(iio_format_value);

static ssize_t iio_read_channel_label(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);

        if (indio_dev->info->read_label)
                return indio_dev->info->read_label(indio_dev, this_attr->c, buf);

        if (this_attr->c->extend_name)
                return sprintf(buf, "%s\n", this_attr->c->extend_name);

        return -EINVAL;
}

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_list(char *buf, const int *vals, int type, int length,
                               const char *prefix, const char *suffix)
{
        ssize_t len;
        int stride;
        int i;

        switch (type) {
        case IIO_VAL_INT:
                stride = 1;
                break;
        default:
                stride = 2;
                break;
        }

        len = sysfs_emit(buf, prefix);

        for (i = 0; i <= length - stride; i += stride) {
                if (i != 0) {
                        len += sysfs_emit_at(buf, len, " ");
                        if (len >= PAGE_SIZE)
                                return -EFBIG;
                }

                len += __iio_format_value(buf, len, type, stride, &vals[i]);
                if (len >= PAGE_SIZE)
                        return -EFBIG;
        }

        len += sysfs_emit_at(buf, len, "%s\n", suffix);

        return len;
}

static ssize_t iio_format_avail_list(char *buf, const int *vals,
                                     int type, int length)
{

        return iio_format_list(buf, vals, type, length, "", "");
}

static ssize_t iio_format_avail_range(char *buf, const int *vals, int type)
{
        return iio_format_list(buf, vals, type, 3, "[", "]");
}

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
 * @scale_db: True if this should parse as dB
 *
 * Returns 0 on success, or a negative error code if the string could not be
 * parsed.
 */
static int __iio_str_to_fixpoint(const char *str, int fract_mult,
                                 int *integer, int *fract, bool scale_db)
{
        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 (!strncmp(str, " dB", sizeof(" dB") - 1) && scale_db) {
                        /* Ignore the dB suffix */
                        str += sizeof(" dB") - 1;
                        continue;
                } else if (!strncmp(str, "dB", sizeof("dB") - 1) && scale_db) {
                        /* Ignore the dB suffix */
                        str += sizeof("dB") - 1;
                        continue;
                } 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;
}

/**
 * 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)
{
        return __iio_str_to_fixpoint(str, fract_mult, integer, fract, false);
}
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 = 0;
        bool is_char = false;
        bool scale_db = false;

        /* 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_DB:
                        scale_db = true;
                        fallthrough;
                case IIO_VAL_INT_PLUS_MICRO:
                        fract_mult = 100000;
                        break;
                case IIO_VAL_INT_PLUS_NANO:
                        fract_mult = 100000000;
                        break;
                case IIO_VAL_CHAR:
                        is_char = true;
                        break;
                default:
                        return -EINVAL;
                }

        if (is_char) {
                char ch;

                if (sscanf(buf, "%c", &ch) != 1)
                        return -EINVAL;
                integer = ch;
        } else {
                ret = __iio_str_to_fixpoint(buf, fract_mult, &integer, &fract,
                                            scale_db);
                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 iio_buffer *buffer,
                           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;
        iio_attr->buffer = buffer;
        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_channel_label(struct iio_dev *indio_dev,
                                         struct iio_chan_spec const *chan)
{
        struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
        int ret;

        if (!indio_dev->info->read_label && !chan->extend_name)
                return 0;

        ret = __iio_add_chan_devattr("label",
                                     chan,
                                     &iio_read_channel_label,
                                     NULL,
                                     0,
                                     IIO_SEPARATE,
                                     &indio_dev->dev,
                                     NULL,
                                     &iio_dev_opaque->channel_attr_list);
        if (ret < 0)
                return ret;

        return 1;
}

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)
{
        struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
        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,
                                             NULL,
                                             &iio_dev_opaque->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)
{
        struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
        int i, ret, attrcount = 0;
        char *avail_postfix;

        for_each_set_bit(i, infomask, sizeof(*infomask) * 8) {
                if (i >= ARRAY_SIZE(iio_chan_info_postfix))
                        return -EINVAL;
                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,
                                             NULL,
                                             &iio_dev_opaque->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)
{
        struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
        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;

        ret = iio_device_add_channel_label(indio_dev, chan);
        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,
                                        NULL,
                                        &iio_dev_opaque->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_const(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 sysfs_emit(buf, "%s\n", indio_dev->name);
}

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

static ssize_t iio_show_dev_label(struct device *dev,
                                 struct device_attribute *attr,
                                 char *buf)
{
        struct iio_dev *indio_dev = dev_to_iio_dev(dev);
        return sysfs_emit(buf, "%s\n", indio_dev->label);
}

static DEVICE_ATTR(label, S_IRUGO, iio_show_dev_label, 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;
}

int iio_device_register_sysfs_group(struct iio_dev *indio_dev,
                                    const struct attribute_group *group)
{
        struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
        const struct attribute_group **new, **old = iio_dev_opaque->groups;
        unsigned int cnt = iio_dev_opaque->groupcounter;

        new = krealloc(old, sizeof(*new) * (cnt + 2), GFP_KERNEL);
        if (!new)
                return -ENOMEM;

        new[iio_dev_opaque->groupcounter++] = group;
        new[iio_dev_opaque->groupcounter] = NULL;

        iio_dev_opaque->groups = new;

        return 0;
}

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)
{
        struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(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 (iio_dev_opaque->event_interface)
                clk = &dev_attr_current_timestamp_clock.attr;

        if (indio_dev->name)
                attrcount++;
        if (indio_dev->label)
                attrcount++;
        if (clk)
                attrcount++;

        iio_dev_opaque->chan_attr_group.attrs =
                kcalloc(attrcount + 1,
                        sizeof(iio_dev_opaque->chan_attr_group.attrs[0]),
                        GFP_KERNEL);
        if (iio_dev_opaque->chan_attr_group.attrs == NULL) {
                ret = -ENOMEM;
                goto error_clear_attrs;
        }
        /* Copy across original attributes */
        if (indio_dev->info->attrs) {
                memcpy(iio_dev_opaque->chan_attr_group.attrs,
                       indio_dev->info->attrs->attrs,
                       sizeof(iio_dev_opaque->chan_attr_group.attrs[0])
                       *attrcount_orig);
                iio_dev_opaque->chan_attr_group.is_visible =
                        indio_dev->info->attrs->is_visible;
        }
        attrn = attrcount_orig;
        /* Add all elements from the list. */
        list_for_each_entry(p, &iio_dev_opaque->channel_attr_list, l)
                iio_dev_opaque->chan_attr_group.attrs[attrn++] = &p->dev_attr.attr;
        if (indio_dev->name)
                iio_dev_opaque->chan_attr_group.attrs[attrn++] = &dev_attr_name.attr;
        if (indio_dev->label)
                iio_dev_opaque->chan_attr_group.attrs[attrn++] = &dev_attr_label.attr;
        if (clk)
                iio_dev_opaque->chan_attr_group.attrs[attrn++] = clk;

        ret = iio_device_register_sysfs_group(indio_dev,
                                              &iio_dev_opaque->chan_attr_group);
        if (ret)
                goto error_clear_attrs;

        return 0;

error_clear_attrs:
        iio_free_chan_devattr_list(&iio_dev_opaque->channel_attr_list);

        return ret;
}

static void iio_device_unregister_sysfs(struct iio_dev *indio_dev)
{
        struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);

        iio_free_chan_devattr_list(&iio_dev_opaque->channel_attr_list);
        kfree(iio_dev_opaque->chan_attr_group.attrs);
        iio_dev_opaque->chan_attr_group.attrs = NULL;
        kfree(iio_dev_opaque->groups);
}

static void iio_dev_release(struct device *device)
{
        struct iio_dev *indio_dev = dev_to_iio_dev(device);
        struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);

        if (indio_dev->modes & INDIO_ALL_TRIGGERED_MODES)
                iio_device_unregister_trigger_consumer(indio_dev);
        iio_device_unregister_eventset(indio_dev);
        iio_device_unregister_sysfs(indio_dev);

        iio_device_detach_buffers(indio_dev);

        ida_simple_remove(&iio_ida, iio_dev_opaque->id);
        kfree(iio_dev_opaque);
}

struct device_type iio_device_type = {
        .name = "iio_device",
        .release = iio_dev_release,
};

/**
 * iio_device_alloc() - allocate an iio_dev from a driver
 * @parent:             Parent device.
 * @sizeof_priv:        Space to allocate for private structure.
 **/
struct iio_dev *iio_device_alloc(struct device *parent, int sizeof_priv)
{
        struct iio_dev_opaque *iio_dev_opaque;
        struct iio_dev *indio_dev;
        size_t alloc_size;

        alloc_size = sizeof(struct iio_dev_opaque);
        if (sizeof_priv) {
                alloc_size = ALIGN(alloc_size, IIO_ALIGN);
                alloc_size += sizeof_priv;
        }

        iio_dev_opaque = kzalloc(alloc_size, GFP_KERNEL);
        if (!iio_dev_opaque)
                return NULL;

        indio_dev = &iio_dev_opaque->indio_dev;
        indio_dev->priv = (char *)iio_dev_opaque +
                ALIGN(sizeof(struct iio_dev_opaque), IIO_ALIGN);

        indio_dev->dev.parent = parent;
        indio_dev->dev.type = &iio_device_type;
        indio_dev->dev.bus = &iio_bus_type;
        device_initialize(&indio_dev->dev);
        iio_device_set_drvdata(indio_dev, (void *)indio_dev);
        mutex_init(&indio_dev->mlock);
        mutex_init(&iio_dev_opaque->info_exist_lock);
        INIT_LIST_HEAD(&iio_dev_opaque->channel_attr_list);

        iio_dev_opaque->id = ida_simple_get(&iio_ida, 0, 0, GFP_KERNEL);
        if (iio_dev_opaque->id < 0) {
                /* cannot use a dev_err as the name isn't available */
                pr_err("failed to get device id\n");
                kfree(iio_dev_opaque);
                return NULL;
        }
        dev_set_name(&indio_dev->dev, "iio:device%d", iio_dev_opaque->id);
        INIT_LIST_HEAD(&iio_dev_opaque->buffer_list);
        INIT_LIST_HEAD(&iio_dev_opaque->ioctl_handlers);

        return indio_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(void *iio_dev)
{
        iio_device_free(iio_dev);
}

/**
 * devm_iio_device_alloc - Resource-managed iio_device_alloc()
 * @parent:             Device to allocate iio_dev for, and parent for this IIO device
 * @sizeof_priv:        Space to allocate for private structure.
 *
 * Managed iio_device_alloc. iio_dev allocated with this function is
 * automatically freed on driver detach.
 *
 * RETURNS:
 * Pointer to allocated iio_dev on success, NULL on failure.
 */
struct iio_dev *devm_iio_device_alloc(struct device *parent, int sizeof_priv)
{
        struct iio_dev *iio_dev;
        int ret;

        iio_dev = iio_device_alloc(parent, sizeof_priv);
        if (!iio_dev)
                return NULL;

        ret = devm_add_action_or_reset(parent, devm_iio_device_release,
                                       iio_dev);
        if (ret)
                return NULL;

        return iio_dev;
}
EXPORT_SYMBOL_GPL(devm_iio_device_alloc);

/**
 * 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_opaque *iio_dev_opaque =
                container_of(inode->i_cdev, struct iio_dev_opaque, chrdev);
        struct iio_dev *indio_dev = &iio_dev_opaque->indio_dev;
        struct iio_dev_buffer_pair *ib;

        if (test_and_set_bit(IIO_BUSY_BIT_POS, &iio_dev_opaque->flags))
                return -EBUSY;

        iio_device_get(indio_dev);

        ib = kmalloc(sizeof(*ib), GFP_KERNEL);
        if (!ib) {
                iio_device_put(indio_dev);
                clear_bit(IIO_BUSY_BIT_POS, &iio_dev_opaque->flags);
                return -ENOMEM;
        }

        ib->indio_dev = indio_dev;
        ib->buffer = indio_dev->buffer;

        filp->private_data = ib;

        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_buffer_pair *ib = filp->private_data;
        struct iio_dev_opaque *iio_dev_opaque =
                container_of(inode->i_cdev, struct iio_dev_opaque, chrdev);
        struct iio_dev *indio_dev = &iio_dev_opaque->indio_dev;
        kfree(ib);
        clear_bit(IIO_BUSY_BIT_POS, &iio_dev_opaque->flags);
        iio_device_put(indio_dev);

        return 0;
}

void iio_device_ioctl_handler_register(struct iio_dev *indio_dev,
                                       struct iio_ioctl_handler *h)
{
        struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);

        list_add_tail(&h->entry, &iio_dev_opaque->ioctl_handlers);
}

void iio_device_ioctl_handler_unregister(struct iio_ioctl_handler *h)
{
        list_del(&h->entry);
}

static long iio_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
        struct iio_dev_buffer_pair *ib = filp->private_data;
        struct iio_dev *indio_dev = ib->indio_dev;
        struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
        struct iio_ioctl_handler *h;
        int ret = -ENODEV;

        mutex_lock(&iio_dev_opaque->info_exist_lock);

        /**
         * The NULL check here is required to prevent crashing when a device
         * is being removed while userspace would still have open file handles
         * to try to access this device.
         */
        if (!indio_dev->info)
                goto out_unlock;

        list_for_each_entry(h, &iio_dev_opaque->ioctl_handlers, entry) {
                ret = h->ioctl(indio_dev, filp, cmd, arg);
                if (ret != IIO_IOCTL_UNHANDLED)
                        break;
        }

        if (ret == IIO_IOCTL_UNHANDLED)
                ret = -ENODEV;

out_unlock:
        mutex_unlock(&iio_dev_opaque->info_exist_lock);

        return ret;
}

static const struct file_operations iio_buffer_fileops = {
        .owner = THIS_MODULE,
        .llseek = noop_llseek,
        .read = iio_buffer_read_outer_addr,
        .poll = iio_buffer_poll_addr,
        .unlocked_ioctl = iio_ioctl,
        .compat_ioctl = compat_ptr_ioctl,
        .open = iio_chrdev_open,
        .release = iio_chrdev_release,
};

static const struct file_operations iio_event_fileops = {
        .owner = THIS_MODULE,
        .llseek = noop_llseek,
        .unlocked_ioctl = iio_ioctl,
        .compat_ioctl = compat_ptr_ioctl,
        .open = iio_chrdev_open,
        .release = iio_chrdev_release,
};

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 int iio_check_extended_name(const struct iio_dev *indio_dev)
{
        unsigned int i;

        if (!indio_dev->info->read_label)
                return 0;

        for (i = 0; i < indio_dev->num_channels; i++) {
                if (indio_dev->channels[i].extend_name) {
                        dev_err(&indio_dev->dev,
                                "Cannot use labels and extend_name at the same time\n");
                        return -EINVAL;
                }
        }

        return 0;
}

static const struct iio_buffer_setup_ops noop_ring_setup_ops;

int __iio_device_register(struct iio_dev *indio_dev, struct module *this_mod)
{
        struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
        const char *label;
        int ret;

        if (!indio_dev->info)
                return -EINVAL;

        iio_dev_opaque->driver_module = this_mod;
        /* 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;

        label = of_get_property(indio_dev->dev.of_node, "label", NULL);
        if (label)
                indio_dev->label = label;

        ret = iio_check_unique_scan_index(indio_dev);
        if (ret < 0)
                return ret;

        ret = iio_check_extended_name(indio_dev);
        if (ret < 0)
                return ret;

        iio_device_register_debugfs(indio_dev);

        ret = iio_buffers_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_ALL_TRIGGERED_MODES)
                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;

        if (iio_dev_opaque->attached_buffers_cnt)
                cdev_init(&iio_dev_opaque->chrdev, &iio_buffer_fileops);
        else if (iio_dev_opaque->event_interface)
                cdev_init(&iio_dev_opaque->chrdev, &iio_event_fileops);

        if (iio_dev_opaque->attached_buffers_cnt || iio_dev_opaque->event_interface) {
                indio_dev->dev.devt = MKDEV(MAJOR(iio_devt), iio_dev_opaque->id);
                iio_dev_opaque->chrdev.owner = this_mod;
        }

        /* assign device groups now; they should be all registered now */
        indio_dev->dev.groups = iio_dev_opaque->groups;

        ret = cdev_device_add(&iio_dev_opaque->chrdev, &indio_dev->dev);
        if (ret < 0)
                goto error_unreg_eventset;

        return 0;

error_unreg_eventset:
        iio_device_unregister_eventset(indio_dev);
error_free_sysfs:
        iio_device_unregister_sysfs(indio_dev);
error_buffer_free_sysfs:
        iio_buffers_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)
{
        struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);

        cdev_device_del(&iio_dev_opaque->chrdev, &indio_dev->dev);

        mutex_lock(&iio_dev_opaque->info_exist_lock);

        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(&iio_dev_opaque->info_exist_lock);

        iio_buffers_free_sysfs_and_mask(indio_dev);
}
EXPORT_SYMBOL(iio_device_unregister);

static void devm_iio_device_unreg(void *indio_dev)
{
        iio_device_unregister(indio_dev);
}

int __devm_iio_device_register(struct device *dev, struct iio_dev *indio_dev,
                               struct module *this_mod)
{
        int ret;

        ret = __iio_device_register(indio_dev, this_mod);
        if (ret)
                return ret;

        return devm_add_action_or_reset(dev, devm_iio_device_unreg, indio_dev);
}
EXPORT_SYMBOL_GPL(__devm_iio_device_register);

/**
 * 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");