/* The industrial I/O core, trigger handling functions
 *
 * Copyright (c) 2008 Jonathan Cameron
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published by
 * the Free Software Foundation.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/idr.h>
#include <linux/err.h>
#include <linux/device.h>
#include <linux/interrupt.h>
#include <linux/list.h>

#include "iio.h"
#include "trigger.h"

/* RFC - Question of approach
 * Make the common case (single sensor single trigger)
 * simple by starting trigger capture from when first sensors
 * is added.
 *
 * Complex simultaneous start requires use of 'hold' functionality
 * of the trigger. (not implemented)
 *
 * Any other suggestions?
 */


static DEFINE_IDR(iio_trigger_idr);
static DEFINE_SPINLOCK(iio_trigger_idr_lock);

/* Single list of all available triggers */
static LIST_HEAD(iio_trigger_list);
static DEFINE_MUTEX(iio_trigger_list_lock);

/**
 * iio_trigger_register_sysfs() - create a device for this trigger
 * @trig_info:  the trigger
 *
 * Also adds any control attribute registered by the trigger driver
 **/
static int iio_trigger_register_sysfs(struct iio_trigger *trig_info)
{
        int ret = 0;

        if (trig_info->control_attrs)
                ret = sysfs_create_group(&trig_info->dev.kobj,
                                         trig_info->control_attrs);

        return ret;
}

static void iio_trigger_unregister_sysfs(struct iio_trigger *trig_info)
{
        if (trig_info->control_attrs)
                sysfs_remove_group(&trig_info->dev.kobj,
                                   trig_info->control_attrs);
}


/**
 * iio_trigger_register_id() - get a unique id for this trigger
 * @trig_info:  the trigger
 **/
static int iio_trigger_register_id(struct iio_trigger *trig_info)
{
        int ret = 0;

idr_again:
        if (unlikely(idr_pre_get(&iio_trigger_idr, GFP_KERNEL) == 0))
                return -ENOMEM;

        spin_lock(&iio_trigger_idr_lock);
        ret = idr_get_new(&iio_trigger_idr, NULL, &trig_info->id);
        spin_unlock(&iio_trigger_idr_lock);
        if (unlikely(ret == -EAGAIN))
                goto idr_again;
        else if (likely(!ret))
                trig_info->id = trig_info->id & MAX_ID_MASK;

        return ret;
}

/**
 * iio_trigger_unregister_id() - free up unique id for use by another trigger
 * @trig_info: the trigger
 **/
static void iio_trigger_unregister_id(struct iio_trigger *trig_info)
{
                spin_lock(&iio_trigger_idr_lock);
                idr_remove(&iio_trigger_idr, trig_info->id);
                spin_unlock(&iio_trigger_idr_lock);
}

int iio_trigger_register(struct iio_trigger *trig_info)
{
        int ret;

        ret = iio_trigger_register_id(trig_info);
        if (ret)
                goto error_ret;
        /* Set the name used for the sysfs directory etc */
        dev_set_name(&trig_info->dev, "trigger%ld",
                     (unsigned long) trig_info->id);

        ret = device_add(&trig_info->dev);
        if (ret)
                goto error_unregister_id;

        ret = iio_trigger_register_sysfs(trig_info);
        if (ret)
                goto error_device_del;

        /* Add to list of available triggers held by the IIO core */
        mutex_lock(&iio_trigger_list_lock);
        list_add_tail(&trig_info->list, &iio_trigger_list);
        mutex_unlock(&iio_trigger_list_lock);

        return 0;

error_device_del:
        device_del(&trig_info->dev);
error_unregister_id:
        iio_trigger_unregister_id(trig_info);
error_ret:
        return ret;
}
EXPORT_SYMBOL(iio_trigger_register);

void iio_trigger_unregister(struct iio_trigger *trig_info)
{
        struct iio_trigger *cursor;

        mutex_lock(&iio_trigger_list_lock);
        list_for_each_entry(cursor, &iio_trigger_list, list)
                if (cursor == trig_info) {
                        list_del(&cursor->list);
                        break;
                }
        mutex_unlock(&iio_trigger_list_lock);

        iio_trigger_unregister_sysfs(trig_info);
        iio_trigger_unregister_id(trig_info);
        /* Possible issue in here */
        device_unregister(&trig_info->dev);
}
EXPORT_SYMBOL(iio_trigger_unregister);

struct iio_trigger *iio_trigger_find_by_name(const char *name, size_t len)
{
        struct iio_trigger *trig;
        bool found = false;

        mutex_lock(&iio_trigger_list_lock);
        list_for_each_entry(trig, &iio_trigger_list, list) {
                if (strncmp(trig->name, name, len) == 0) {
                        found = true;
                        break;
                }
        }
        mutex_unlock(&iio_trigger_list_lock);

        return found ? trig : NULL;
};
EXPORT_SYMBOL(iio_trigger_find_by_name);

void iio_trigger_poll(struct iio_trigger *trig)
{
        struct iio_poll_func *pf_cursor;

        list_for_each_entry(pf_cursor, &trig->pollfunc_list, list) {
                if (pf_cursor->poll_func_immediate) {
                        pf_cursor->poll_func_immediate(pf_cursor->private_data);
                        trig->use_count++;
                }
        }
        list_for_each_entry(pf_cursor, &trig->pollfunc_list, list) {
                if (pf_cursor->poll_func_main) {
                        pf_cursor->poll_func_main(pf_cursor->private_data);
                        trig->use_count++;
                }
        }
}
EXPORT_SYMBOL(iio_trigger_poll);

void iio_trigger_notify_done(struct iio_trigger *trig)
{
        trig->use_count--;
        if (trig->use_count == 0 && trig->try_reenable)
                if (trig->try_reenable(trig)) {
                        /* Missed and interrupt so launch new poll now */
                        trig->timestamp = 0;
                        iio_trigger_poll(trig);
                }
}
EXPORT_SYMBOL(iio_trigger_notify_done);

/**
 * iio_trigger_read_name() - retrieve useful identifying name
 **/
ssize_t iio_trigger_read_name(struct device *dev,
                              struct device_attribute *attr,
                              char *buf)
{
        struct iio_trigger *trig = dev_get_drvdata(dev);
        return sprintf(buf, "%s\n", trig->name);
}
EXPORT_SYMBOL(iio_trigger_read_name);

/* Trigger Consumer related functions */

/* Complexity in here.  With certain triggers (datardy) an acknowledgement
 * may be needed if the pollfuncs do not include the data read for the
 * triggering device.
 * This is not currently handled.  Alternative of not enabling trigger unless
 * the relevant function is in there may be the best option.
 */
/* Worth protecting against double additions?*/
int iio_trigger_attach_poll_func(struct iio_trigger *trig,
                                 struct iio_poll_func *pf)
{
        int ret = 0;
        unsigned long flags;

        spin_lock_irqsave(&trig->pollfunc_list_lock, flags);
        list_add_tail(&pf->list, &trig->pollfunc_list);
        spin_unlock_irqrestore(&trig->pollfunc_list_lock, flags);

        if (trig->set_trigger_state)
                ret = trig->set_trigger_state(trig, true);
        if (ret) {
                printk(KERN_ERR "set trigger state failed\n");
                list_del(&pf->list);
        }
        return ret;
}
EXPORT_SYMBOL(iio_trigger_attach_poll_func);

int iio_trigger_dettach_poll_func(struct iio_trigger *trig,
                                  struct iio_poll_func *pf)
{
        struct iio_poll_func *pf_cursor;
        unsigned long flags;
        int ret = -EINVAL;

        spin_lock_irqsave(&trig->pollfunc_list_lock, flags);
        list_for_each_entry(pf_cursor, &trig->pollfunc_list, list)
                if (pf_cursor == pf) {
                        ret = 0;
                        break;
                }
        if (!ret) {
                if (list_is_singular(&trig->pollfunc_list)
                    && trig->set_trigger_state) {
                        spin_unlock_irqrestore(&trig->pollfunc_list_lock,
                                               flags);
                        /* May sleep hence cannot hold the spin lock */
                        ret = trig->set_trigger_state(trig, false);
                        if (ret)
                                goto error_ret;
                        spin_lock_irqsave(&trig->pollfunc_list_lock, flags);
                }
                /*
                 * Now we can delete safe in the knowledge that, if this is
                 * the last pollfunc then we have disabled the trigger anyway
                 * and so nothing should be able to call the pollfunc.
                 */
                list_del(&pf_cursor->list);
        }
        spin_unlock_irqrestore(&trig->pollfunc_list_lock, flags);

error_ret:
        return ret;
}
EXPORT_SYMBOL(iio_trigger_dettach_poll_func);

/**
 * iio_trigger_read_currrent() trigger consumer sysfs query which trigger
 *
 * For trigger consumers the current_trigger interface allows the trigger
 * used by the device to be queried.
 **/
static ssize_t iio_trigger_read_current(struct device *dev,
                                        struct device_attribute *attr,
                                        char *buf)
{
        struct iio_dev *dev_info = dev_get_drvdata(dev);
        int len = 0;
        if (dev_info->trig)
                len = snprintf(buf,
                               IIO_TRIGGER_NAME_LENGTH,
                               "%s\n",
                               dev_info->trig->name);
        return len;
}

/**
 * iio_trigger_write_current() trigger consumer sysfs set current trigger
 *
 * For trigger consumers the current_trigger interface allows the trigger
 * used for this device to be specified at run time based on the triggers
 * name.
 **/
static ssize_t iio_trigger_write_current(struct device *dev,
                                         struct device_attribute *attr,
                                         const char *buf,
                                         size_t len)
{
        struct iio_dev *dev_info = dev_get_drvdata(dev);
        struct iio_trigger *oldtrig = dev_info->trig;
        mutex_lock(&dev_info->mlock);
        if (dev_info->currentmode == INDIO_RING_TRIGGERED) {
                mutex_unlock(&dev_info->mlock);
                return -EBUSY;
        }
        mutex_unlock(&dev_info->mlock);

        len = len < IIO_TRIGGER_NAME_LENGTH ? len : IIO_TRIGGER_NAME_LENGTH;

        dev_info->trig = iio_trigger_find_by_name(buf, len);
        if (oldtrig && dev_info->trig != oldtrig)
                iio_put_trigger(oldtrig);
        if (dev_info->trig)
                iio_get_trigger(dev_info->trig);

        return len;
}

DEVICE_ATTR(current_trigger, S_IRUGO | S_IWUSR,
            iio_trigger_read_current,
            iio_trigger_write_current);

static struct attribute *iio_trigger_consumer_attrs[] = {
        &dev_attr_current_trigger.attr,
        NULL,
};

static const struct attribute_group iio_trigger_consumer_attr_group = {
        .name = "trigger",
        .attrs = iio_trigger_consumer_attrs,
};

static void iio_trig_release(struct device *device)
{
        struct iio_trigger *trig = to_iio_trigger(device);
        kfree(trig);
        iio_put();
}

static struct device_type iio_trig_type = {
        .release = iio_trig_release,
};

struct iio_trigger *iio_allocate_trigger(void)
{
        struct iio_trigger *trig;
        trig = kzalloc(sizeof *trig, GFP_KERNEL);
        if (trig) {
                trig->dev.type = &iio_trig_type;
                trig->dev.class = &iio_class;
                device_initialize(&trig->dev);
                dev_set_drvdata(&trig->dev, (void *)trig);
                spin_lock_init(&trig->pollfunc_list_lock);
                INIT_LIST_HEAD(&trig->list);
                INIT_LIST_HEAD(&trig->pollfunc_list);
                iio_get();
        }
        return trig;
}
EXPORT_SYMBOL(iio_allocate_trigger);

void iio_free_trigger(struct iio_trigger *trig)
{
        if (trig)
                put_device(&trig->dev);
}
EXPORT_SYMBOL(iio_free_trigger);

int iio_device_register_trigger_consumer(struct iio_dev *dev_info)
{
        int ret;
        ret = sysfs_create_group(&dev_info->dev.kobj,
                                 &iio_trigger_consumer_attr_group);
        return ret;
}
EXPORT_SYMBOL(iio_device_register_trigger_consumer);

int iio_device_unregister_trigger_consumer(struct iio_dev *dev_info)
{
        sysfs_remove_group(&dev_info->dev.kobj,
                           &iio_trigger_consumer_attr_group);
        return 0;
}
EXPORT_SYMBOL(iio_device_unregister_trigger_consumer);