// SPDX-License-Identifier: GPL-2.0-only
/* Industrial I/O event handling
 *
 * Copyright (c) 2008 Jonathan Cameron
 *
 * Based on elements of hwmon and input subsystems.
 */

#include <linux/anon_inodes.h>
#include <linux/device.h>
#include <linux/fs.h>
#include <linux/kernel.h>
#include <linux/kfifo.h>
#include <linux/module.h>
#include <linux/poll.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/wait.h>
#include <linux/iio/iio.h>
#include <linux/iio/iio-opaque.h>
#include "iio_core.h"
#include <linux/iio/sysfs.h>
#include <linux/iio/events.h>

/**
 * struct iio_event_interface - chrdev interface for an event line
 * @wait:               wait queue to allow blocking reads of events
 * @det_events:         list of detected events
 * @dev_attr_list:      list of event interface sysfs attribute
 * @flags:              file operations related flags including busy flag.
 * @group:              event interface sysfs attribute group
 * @read_lock:          lock to protect kfifo read operations
 * @ioctl_handler:      handler for event ioctl() calls
 */
struct iio_event_interface {
        wait_queue_head_t       wait;
        DECLARE_KFIFO(det_events, struct iio_event_data, 16);

        struct list_head        dev_attr_list;
        unsigned long           flags;
        struct attribute_group  group;
        struct mutex            read_lock;
        struct iio_ioctl_handler        ioctl_handler;
};

bool iio_event_enabled(const struct iio_event_interface *ev_int)
{
        return !!test_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
}

/**
 * iio_push_event() - try to add event to the list for userspace reading
 * @indio_dev:          IIO device structure
 * @ev_code:            What event
 * @timestamp:          When the event occurred
 *
 * Note: The caller must make sure that this function is not running
 * concurrently for the same indio_dev more than once.
 *
 * This function may be safely used as soon as a valid reference to iio_dev has
 * been obtained via iio_device_alloc(), but any events that are submitted
 * before iio_device_register() has successfully completed will be silently
 * discarded.
 **/
int iio_push_event(struct iio_dev *indio_dev, u64 ev_code, s64 timestamp)
{
        struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
        struct iio_event_interface *ev_int = iio_dev_opaque->event_interface;
        struct iio_event_data ev;
        int copied;

        if (!ev_int)
                return 0;

        /* Does anyone care? */
        if (iio_event_enabled(ev_int)) {

                ev.id = ev_code;
                ev.timestamp = timestamp;

                copied = kfifo_put(&ev_int->det_events, ev);
                if (copied != 0)
                        wake_up_poll(&ev_int->wait, EPOLLIN);
        }

        return 0;
}
EXPORT_SYMBOL(iio_push_event);

/**
 * iio_event_poll() - poll the event queue to find out if it has data
 * @filep:      File structure pointer to identify the device
 * @wait:       Poll table pointer to add the wait queue on
 *
 * Return: (EPOLLIN | EPOLLRDNORM) if data is available for reading
 *         or a negative error code on failure
 */
static __poll_t iio_event_poll(struct file *filep,
                             struct poll_table_struct *wait)
{
        struct iio_dev *indio_dev = filep->private_data;
        struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
        struct iio_event_interface *ev_int = iio_dev_opaque->event_interface;
        __poll_t events = 0;

        if (!indio_dev->info)
                return events;

        poll_wait(filep, &ev_int->wait, wait);

        if (!kfifo_is_empty(&ev_int->det_events))
                events = EPOLLIN | EPOLLRDNORM;

        return events;
}

static ssize_t iio_event_chrdev_read(struct file *filep,
                                     char __user *buf,
                                     size_t count,
                                     loff_t *f_ps)
{
        struct iio_dev *indio_dev = filep->private_data;
        struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
        struct iio_event_interface *ev_int = iio_dev_opaque->event_interface;
        unsigned int copied;
        int ret;

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

        if (count < sizeof(struct iio_event_data))
                return -EINVAL;

        do {
                if (kfifo_is_empty(&ev_int->det_events)) {
                        if (filep->f_flags & O_NONBLOCK)
                                return -EAGAIN;

                        ret = wait_event_interruptible(ev_int->wait,
                                        !kfifo_is_empty(&ev_int->det_events) ||
                                        indio_dev->info == NULL);
                        if (ret)
                                return ret;
                        if (indio_dev->info == NULL)
                                return -ENODEV;
                }

                if (mutex_lock_interruptible(&ev_int->read_lock))
                        return -ERESTARTSYS;
                ret = kfifo_to_user(&ev_int->det_events, buf, count, &copied);
                mutex_unlock(&ev_int->read_lock);

                if (ret)
                        return ret;

                /*
                 * If we couldn't read anything from the fifo (a different
                 * thread might have been faster) we either return -EAGAIN if
                 * the file descriptor is non-blocking, otherwise we go back to
                 * sleep and wait for more data to arrive.
                 */
                if (copied == 0 && (filep->f_flags & O_NONBLOCK))
                        return -EAGAIN;

        } while (copied == 0);

        return copied;
}

static int iio_event_chrdev_release(struct inode *inode, struct file *filep)
{
        struct iio_dev *indio_dev = filep->private_data;
        struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
        struct iio_event_interface *ev_int = iio_dev_opaque->event_interface;

        clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags);

        iio_device_put(indio_dev);

        return 0;
}

static const struct file_operations iio_event_chrdev_fileops = {
        .read =  iio_event_chrdev_read,
        .poll =  iio_event_poll,
        .release = iio_event_chrdev_release,
        .owner = THIS_MODULE,
        .llseek = noop_llseek,
};

static int iio_event_getfd(struct iio_dev *indio_dev)
{
        struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
        struct iio_event_interface *ev_int = iio_dev_opaque->event_interface;
        int fd;

        if (ev_int == NULL)
                return -ENODEV;

        fd = mutex_lock_interruptible(&iio_dev_opaque->mlock);
        if (fd)
                return fd;

        if (test_and_set_bit(IIO_BUSY_BIT_POS, &ev_int->flags)) {
                fd = -EBUSY;
                goto unlock;
        }

        iio_device_get(indio_dev);

        fd = anon_inode_getfd("iio:event", &iio_event_chrdev_fileops,
                                indio_dev, O_RDONLY | O_CLOEXEC);
        if (fd < 0) {
                clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
                iio_device_put(indio_dev);
        } else {
                kfifo_reset_out(&ev_int->det_events);
        }

unlock:
        mutex_unlock(&iio_dev_opaque->mlock);
        return fd;
}

static const char * const iio_ev_type_text[] = {
        [IIO_EV_TYPE_THRESH] = "thresh",
        [IIO_EV_TYPE_MAG] = "mag",
        [IIO_EV_TYPE_ROC] = "roc",
        [IIO_EV_TYPE_THRESH_ADAPTIVE] = "thresh_adaptive",
        [IIO_EV_TYPE_MAG_ADAPTIVE] = "mag_adaptive",
        [IIO_EV_TYPE_CHANGE] = "change",
        [IIO_EV_TYPE_MAG_REFERENCED] = "mag_referenced",
        [IIO_EV_TYPE_GESTURE] = "gesture",
        [IIO_EV_TYPE_FAULT] = "fault",
};

static const char * const iio_ev_dir_text[] = {
        [IIO_EV_DIR_EITHER] = "either",
        [IIO_EV_DIR_RISING] = "rising",
        [IIO_EV_DIR_FALLING] = "falling",
        [IIO_EV_DIR_SINGLETAP] = "singletap",
        [IIO_EV_DIR_DOUBLETAP] = "doubletap",
        [IIO_EV_DIR_FAULT_OPENWIRE] = "openwire",
};

static const char * const iio_ev_info_text[] = {
        [IIO_EV_INFO_ENABLE] = "en",
        [IIO_EV_INFO_VALUE] = "value",
        [IIO_EV_INFO_HYSTERESIS] = "hysteresis",
        [IIO_EV_INFO_PERIOD] = "period",
        [IIO_EV_INFO_HIGH_PASS_FILTER_3DB] = "high_pass_filter_3db",
        [IIO_EV_INFO_LOW_PASS_FILTER_3DB] = "low_pass_filter_3db",
        [IIO_EV_INFO_TIMEOUT] = "timeout",
        [IIO_EV_INFO_RESET_TIMEOUT] = "reset_timeout",
        [IIO_EV_INFO_TAP2_MIN_DELAY] = "tap2_min_delay",
        [IIO_EV_INFO_RUNNING_PERIOD] = "runningperiod",
        [IIO_EV_INFO_RUNNING_COUNT] = "runningcount",
};

static enum iio_event_direction iio_ev_attr_dir(struct iio_dev_attr *attr)
{
        return attr->c->event_spec[attr->address & 0xffff].dir;
}

static enum iio_event_type iio_ev_attr_type(struct iio_dev_attr *attr)
{
        return attr->c->event_spec[attr->address & 0xffff].type;
}

static enum iio_event_info iio_ev_attr_info(struct iio_dev_attr *attr)
{
        return (attr->address >> 16) & 0xffff;
}

static ssize_t iio_ev_state_store(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;
        bool val;

        ret = kstrtobool(buf, &val);
        if (ret < 0)
                return ret;

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

        ret = indio_dev->info->write_event_config(indio_dev,
                this_attr->c, iio_ev_attr_type(this_attr),
                iio_ev_attr_dir(this_attr), val);

        return (ret < 0) ? ret : len;
}

static ssize_t iio_ev_state_show(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;

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

        val = indio_dev->info->read_event_config(indio_dev,
                this_attr->c, iio_ev_attr_type(this_attr),
                iio_ev_attr_dir(this_attr));
        if (val < 0)
                return val;
        else
                return sysfs_emit(buf, "%d\n", val);
}

static ssize_t iio_ev_value_show(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, val_arr[2];
        int ret;

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

        ret = indio_dev->info->read_event_value(indio_dev,
                this_attr->c, iio_ev_attr_type(this_attr),
                iio_ev_attr_dir(this_attr), iio_ev_attr_info(this_attr),
                &val, &val2);
        if (ret < 0)
                return ret;
        val_arr[0] = val;
        val_arr[1] = val2;
        return iio_format_value(buf, ret, 2, val_arr);
}

static ssize_t iio_ev_value_store(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 val, val2;
        int ret;

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

        ret = iio_str_to_fixpoint(buf, 100000, &val, &val2);
        if (ret)
                return ret;
        ret = indio_dev->info->write_event_value(indio_dev,
                this_attr->c, iio_ev_attr_type(this_attr),
                iio_ev_attr_dir(this_attr), iio_ev_attr_info(this_attr),
                val, val2);
        if (ret < 0)
                return ret;

        return len;
}

static ssize_t iio_ev_label_show(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_event_label)
                return indio_dev->info->read_event_label(indio_dev,
                                 this_attr->c, iio_ev_attr_type(this_attr),
                                 iio_ev_attr_dir(this_attr), buf);

        return -EINVAL;
}

static int iio_device_add_event(struct iio_dev *indio_dev,
        const struct iio_chan_spec *chan, unsigned int spec_index,
        enum iio_event_type type, enum iio_event_direction dir,
        enum iio_shared_by shared_by, const unsigned long *mask)
{
        struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
        ssize_t (*show)(struct device *dev, struct device_attribute *attr,
                char *buf);
        ssize_t (*store)(struct device *dev, struct device_attribute *attr,
                const char *buf, size_t len);
        unsigned int attrcount = 0;
        unsigned int i;
        char *postfix;
        int ret;

        for_each_set_bit(i, mask, sizeof(*mask)*8) {
                if (i >= ARRAY_SIZE(iio_ev_info_text))
                        return -EINVAL;
                if (dir != IIO_EV_DIR_NONE)
                        postfix = kasprintf(GFP_KERNEL, "%s_%s_%s",
                                        iio_ev_type_text[type],
                                        iio_ev_dir_text[dir],
                                        iio_ev_info_text[i]);
                else
                        postfix = kasprintf(GFP_KERNEL, "%s_%s",
                                        iio_ev_type_text[type],
                                        iio_ev_info_text[i]);
                if (postfix == NULL)
                        return -ENOMEM;

                if (i == IIO_EV_INFO_ENABLE) {
                        show = iio_ev_state_show;
                        store = iio_ev_state_store;
                } else {
                        show = iio_ev_value_show;
                        store = iio_ev_value_store;
                }

                ret = __iio_add_chan_devattr(postfix, chan, show, store,
                         (i << 16) | spec_index, shared_by, &indio_dev->dev,
                         NULL,
                        &iio_dev_opaque->event_interface->dev_attr_list);
                kfree(postfix);

                if ((ret == -EBUSY) && (shared_by != IIO_SEPARATE))
                        continue;

                if (ret)
                        return ret;

                attrcount++;
        }

        return attrcount;
}

static int iio_device_add_event_label(struct iio_dev *indio_dev,
                                      const struct iio_chan_spec *chan,
                                      unsigned int spec_index,
                                      enum iio_event_type type,
                                      enum iio_event_direction dir)
{
        struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
        char *postfix;
        int ret;

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

        if (dir != IIO_EV_DIR_NONE)
                postfix = kasprintf(GFP_KERNEL, "%s_%s_label",
                                iio_ev_type_text[type],
                                iio_ev_dir_text[dir]);
        else
                postfix = kasprintf(GFP_KERNEL, "%s_label",
                                iio_ev_type_text[type]);
        if (postfix == NULL)
                return -ENOMEM;

        ret = __iio_add_chan_devattr(postfix, chan, &iio_ev_label_show, NULL,
                                spec_index, IIO_SEPARATE, &indio_dev->dev, NULL,
                                &iio_dev_opaque->event_interface->dev_attr_list);

        kfree(postfix);

        if (ret < 0)
                return ret;

        return 1;
}

static int iio_device_add_event_sysfs(struct iio_dev *indio_dev,
        struct iio_chan_spec const *chan)
{
        int ret = 0, i, attrcount = 0;
        enum iio_event_direction dir;
        enum iio_event_type type;

        for (i = 0; i < chan->num_event_specs; i++) {
                type = chan->event_spec[i].type;
                dir = chan->event_spec[i].dir;

                ret = iio_device_add_event(indio_dev, chan, i, type, dir,
                        IIO_SEPARATE, &chan->event_spec[i].mask_separate);
                if (ret < 0)
                        return ret;
                attrcount += ret;

                ret = iio_device_add_event(indio_dev, chan, i, type, dir,
                        IIO_SHARED_BY_TYPE,
                        &chan->event_spec[i].mask_shared_by_type);
                if (ret < 0)
                        return ret;
                attrcount += ret;

                ret = iio_device_add_event(indio_dev, chan, i, type, dir,
                        IIO_SHARED_BY_DIR,
                        &chan->event_spec[i].mask_shared_by_dir);
                if (ret < 0)
                        return ret;
                attrcount += ret;

                ret = iio_device_add_event(indio_dev, chan, i, type, dir,
                        IIO_SHARED_BY_ALL,
                        &chan->event_spec[i].mask_shared_by_all);
                if (ret < 0)
                        return ret;
                attrcount += ret;

                ret = iio_device_add_event_label(indio_dev, chan, i, type, dir);
                if (ret < 0)
                        return ret;
                attrcount += ret;
        }
        ret = attrcount;
        return ret;
}

static inline int __iio_add_event_config_attrs(struct iio_dev *indio_dev)
{
        int j, ret, attrcount = 0;

        /* Dynamically created from the channels array */
        for (j = 0; j < indio_dev->num_channels; j++) {
                ret = iio_device_add_event_sysfs(indio_dev,
                                                 &indio_dev->channels[j]);
                if (ret < 0)
                        return ret;
                attrcount += ret;
        }
        return attrcount;
}

static bool iio_check_for_dynamic_events(struct iio_dev *indio_dev)
{
        int j;

        for (j = 0; j < indio_dev->num_channels; j++) {
                if (indio_dev->channels[j].num_event_specs != 0)
                        return true;
        }
        return false;
}

static void iio_setup_ev_int(struct iio_event_interface *ev_int)
{
        INIT_KFIFO(ev_int->det_events);
        init_waitqueue_head(&ev_int->wait);
        mutex_init(&ev_int->read_lock);
}

static long iio_event_ioctl(struct iio_dev *indio_dev, struct file *filp,
                            unsigned int cmd, unsigned long arg)
{
        int __user *ip = (int __user *)arg;
        int fd;

        if (cmd == IIO_GET_EVENT_FD_IOCTL) {
                fd = iio_event_getfd(indio_dev);
                if (fd < 0)
                        return fd;
                if (copy_to_user(ip, &fd, sizeof(fd)))
                        return -EFAULT;
                return 0;
        }

        return IIO_IOCTL_UNHANDLED;
}

static const char *iio_event_group_name = "events";
int iio_device_register_eventset(struct iio_dev *indio_dev)
{
        struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
        struct iio_event_interface *ev_int;
        struct iio_dev_attr *p;
        int ret = 0, attrcount_orig = 0, attrcount, attrn;
        struct attribute **attr;

        if (!(indio_dev->info->event_attrs ||
              iio_check_for_dynamic_events(indio_dev)))
                return 0;

        ev_int = kzalloc_obj(*ev_int);
        if (!ev_int)
                return -ENOMEM;

        iio_dev_opaque->event_interface = ev_int;

        INIT_LIST_HEAD(&ev_int->dev_attr_list);

        iio_setup_ev_int(ev_int);
        if (indio_dev->info->event_attrs != NULL) {
                attr = indio_dev->info->event_attrs->attrs;
                while (*attr++ != NULL)
                        attrcount_orig++;
        }
        attrcount = attrcount_orig;
        if (indio_dev->channels) {
                ret = __iio_add_event_config_attrs(indio_dev);
                if (ret < 0)
                        goto error_free_setup_event_lines;
                attrcount += ret;
        }

        ev_int->group.name = iio_event_group_name;
        ev_int->group.attrs = kzalloc_objs(ev_int->group.attrs[0],
                                           attrcount + 1);
        if (ev_int->group.attrs == NULL) {
                ret = -ENOMEM;
                goto error_free_setup_event_lines;
        }
        if (indio_dev->info->event_attrs)
                memcpy(ev_int->group.attrs,
                       indio_dev->info->event_attrs->attrs,
                       sizeof(ev_int->group.attrs[0]) * attrcount_orig);
        attrn = attrcount_orig;
        /* Add all elements from the list. */
        list_for_each_entry(p, &ev_int->dev_attr_list, l)
                ev_int->group.attrs[attrn++] = &p->dev_attr.attr;

        ret = iio_device_register_sysfs_group(indio_dev, &ev_int->group);
        if (ret)
                goto error_free_group_attrs;

        ev_int->ioctl_handler.ioctl = iio_event_ioctl;
        iio_device_ioctl_handler_register(&iio_dev_opaque->indio_dev,
                                          &ev_int->ioctl_handler);

        return 0;

error_free_group_attrs:
        kfree(ev_int->group.attrs);
error_free_setup_event_lines:
        iio_free_chan_devattr_list(&ev_int->dev_attr_list);
        kfree(ev_int);
        iio_dev_opaque->event_interface = NULL;
        return ret;
}

/**
 * iio_device_wakeup_eventset - Wakes up the event waitqueue
 * @indio_dev: The IIO device
 *
 * Wakes up the event waitqueue used for poll() and blocking read().
 * Should usually be called when the device is unregistered.
 */
void iio_device_wakeup_eventset(struct iio_dev *indio_dev)
{
        struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);

        if (iio_dev_opaque->event_interface == NULL)
                return;
        wake_up(&iio_dev_opaque->event_interface->wait);
}

void iio_device_unregister_eventset(struct iio_dev *indio_dev)
{
        struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev);
        struct iio_event_interface *ev_int = iio_dev_opaque->event_interface;

        if (ev_int == NULL)
                return;

        iio_device_ioctl_handler_unregister(&ev_int->ioctl_handler);
        iio_free_chan_devattr_list(&ev_int->dev_attr_list);
        kfree(ev_int->group.attrs);
        kfree(ev_int);
        iio_dev_opaque->event_interface = NULL;
}