/**
 * \file drm_fops.c
 * File operations for DRM
 *
 * \author Rickard E. (Rik) Faith <faith@valinux.com>
 * \author Daryll Strauss <daryll@valinux.com>
 * \author Gareth Hughes <gareth@valinux.com>
 */

/*
 * Created: Mon Jan  4 08:58:31 1999 by faith@valinux.com
 *
 * Copyright 1999 Precision Insight, Inc., Cedar Park, Texas.
 * Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California.
 * All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 */

#include "drmP.h"
#include <linux/poll.h>
#include <linux/slab.h>

/* from BKL pushdown: note that nothing else serializes idr_find() */
DEFINE_MUTEX(drm_global_mutex);
EXPORT_SYMBOL(drm_global_mutex);

static int drm_open_helper(struct inode *inode, struct file *filp,
                           struct drm_device * dev);

static int drm_setup(struct drm_device * dev)
{
        int i;
        int ret;

        if (dev->driver->firstopen) {
                ret = dev->driver->firstopen(dev);
                if (ret != 0)
                        return ret;
        }

        atomic_set(&dev->ioctl_count, 0);
        atomic_set(&dev->vma_count, 0);

        if (drm_core_check_feature(dev, DRIVER_HAVE_DMA) &&
            !drm_core_check_feature(dev, DRIVER_MODESET)) {
                dev->buf_use = 0;
                atomic_set(&dev->buf_alloc, 0);

                i = drm_dma_setup(dev);
                if (i < 0)
                        return i;
        }

        for (i = 0; i < ARRAY_SIZE(dev->counts); i++)
                atomic_set(&dev->counts[i], 0);

        dev->sigdata.lock = NULL;

        dev->queue_count = 0;
        dev->queue_reserved = 0;
        dev->queue_slots = 0;
        dev->queuelist = NULL;
        dev->context_flag = 0;
        dev->interrupt_flag = 0;
        dev->dma_flag = 0;
        dev->last_context = 0;
        dev->last_switch = 0;
        dev->last_checked = 0;
        init_waitqueue_head(&dev->context_wait);
        dev->if_version = 0;

        dev->ctx_start = 0;
        dev->lck_start = 0;

        dev->buf_async = NULL;
        init_waitqueue_head(&dev->buf_readers);
        init_waitqueue_head(&dev->buf_writers);

        DRM_DEBUG("\n");

        /*
         * The kernel's context could be created here, but is now created
         * in drm_dma_enqueue.  This is more resource-efficient for
         * hardware that does not do DMA, but may mean that
         * drm_select_queue fails between the time the interrupt is
         * initialized and the time the queues are initialized.
         */

        return 0;
}

/**
 * Open file.
 *
 * \param inode device inode
 * \param filp file pointer.
 * \return zero on success or a negative number on failure.
 *
 * Searches the DRM device with the same minor number, calls open_helper(), and
 * increments the device open count. If the open count was previous at zero,
 * i.e., it's the first that the device is open, then calls setup().
 */
int drm_open(struct inode *inode, struct file *filp)
{
        struct drm_device *dev = NULL;
        int minor_id = iminor(inode);
        struct drm_minor *minor;
        int retcode = 0;

        minor = idr_find(&drm_minors_idr, minor_id);
        if (!minor)
                return -ENODEV;

        if (!(dev = minor->dev))
                return -ENODEV;

        retcode = drm_open_helper(inode, filp, dev);
        if (!retcode) {
                atomic_inc(&dev->counts[_DRM_STAT_OPENS]);
                if (!dev->open_count++)
                        retcode = drm_setup(dev);
        }
        if (!retcode) {
                mutex_lock(&dev->struct_mutex);
                if (minor->type == DRM_MINOR_LEGACY) {
                        if (dev->dev_mapping == NULL)
                                dev->dev_mapping = inode->i_mapping;
                        else if (dev->dev_mapping != inode->i_mapping)
                                retcode = -ENODEV;
                }
                mutex_unlock(&dev->struct_mutex);
        }

        return retcode;
}
EXPORT_SYMBOL(drm_open);

/**
 * File \c open operation.
 *
 * \param inode device inode.
 * \param filp file pointer.
 *
 * Puts the dev->fops corresponding to the device minor number into
 * \p filp, call the \c open method, and restore the file operations.
 */
int drm_stub_open(struct inode *inode, struct file *filp)
{
        struct drm_device *dev = NULL;
        struct drm_minor *minor;
        int minor_id = iminor(inode);
        int err = -ENODEV;
        const struct file_operations *old_fops;

        DRM_DEBUG("\n");

        mutex_lock(&drm_global_mutex);
        minor = idr_find(&drm_minors_idr, minor_id);
        if (!minor)
                goto out;

        if (!(dev = minor->dev))
                goto out;

        old_fops = filp->f_op;
        filp->f_op = fops_get(&dev->driver->fops);
        if (filp->f_op == NULL) {
                filp->f_op = old_fops;
                goto out;
        }
        if (filp->f_op->open && (err = filp->f_op->open(inode, filp))) {
                fops_put(filp->f_op);
                filp->f_op = fops_get(old_fops);
        }
        fops_put(old_fops);

out:
        mutex_unlock(&drm_global_mutex);
        return err;
}

/**
 * Check whether DRI will run on this CPU.
 *
 * \return non-zero if the DRI will run on this CPU, or zero otherwise.
 */
static int drm_cpu_valid(void)
{
#if defined(__i386__)
        if (boot_cpu_data.x86 == 3)
                return 0;       /* No cmpxchg on a 386 */
#endif
#if defined(__sparc__) && !defined(__sparc_v9__)
        return 0;               /* No cmpxchg before v9 sparc. */
#endif
        return 1;
}

/**
 * Called whenever a process opens /dev/drm.
 *
 * \param inode device inode.
 * \param filp file pointer.
 * \param dev device.
 * \return zero on success or a negative number on failure.
 *
 * Creates and initializes a drm_file structure for the file private data in \p
 * filp and add it into the double linked list in \p dev.
 */
static int drm_open_helper(struct inode *inode, struct file *filp,
                           struct drm_device * dev)
{
        int minor_id = iminor(inode);
        struct drm_file *priv;
        int ret;

        if (filp->f_flags & O_EXCL)
                return -EBUSY;  /* No exclusive opens */
        if (!drm_cpu_valid())
                return -EINVAL;
        if (dev->switch_power_state != DRM_SWITCH_POWER_ON)
                return -EINVAL;

        DRM_DEBUG("pid = %d, minor = %d\n", task_pid_nr(current), minor_id);

        priv = kzalloc(sizeof(*priv), GFP_KERNEL);
        if (!priv)
                return -ENOMEM;

        filp->private_data = priv;
        priv->filp = filp;
        priv->uid = current_euid();
        priv->pid = task_pid_nr(current);
        priv->minor = idr_find(&drm_minors_idr, minor_id);
        priv->ioctl_count = 0;
        /* for compatibility root is always authenticated */
        priv->authenticated = capable(CAP_SYS_ADMIN);
        priv->lock_count = 0;

        INIT_LIST_HEAD(&priv->lhead);
        INIT_LIST_HEAD(&priv->fbs);
        INIT_LIST_HEAD(&priv->event_list);
        init_waitqueue_head(&priv->event_wait);
        priv->event_space = 4096; /* set aside 4k for event buffer */

        if (dev->driver->driver_features & DRIVER_GEM)
                drm_gem_open(dev, priv);

        if (dev->driver->open) {
                ret = dev->driver->open(dev, priv);
                if (ret < 0)
                        goto out_free;
        }


        /* if there is no current master make this fd it */
        mutex_lock(&dev->struct_mutex);
        if (!priv->minor->master) {
                /* create a new master */
                priv->minor->master = drm_master_create(priv->minor);
                if (!priv->minor->master) {
                        mutex_unlock(&dev->struct_mutex);
                        ret = -ENOMEM;
                        goto out_free;
                }

                priv->is_master = 1;
                /* take another reference for the copy in the local file priv */
                priv->master = drm_master_get(priv->minor->master);

                priv->authenticated = 1;

                mutex_unlock(&dev->struct_mutex);
                if (dev->driver->master_create) {
                        ret = dev->driver->master_create(dev, priv->master);
                        if (ret) {
                                mutex_lock(&dev->struct_mutex);
                                /* drop both references if this fails */
                                drm_master_put(&priv->minor->master);
                                drm_master_put(&priv->master);
                                mutex_unlock(&dev->struct_mutex);
                                goto out_free;
                        }
                }
                mutex_lock(&dev->struct_mutex);
                if (dev->driver->master_set) {
                        ret = dev->driver->master_set(dev, priv, true);
                        if (ret) {
                                /* drop both references if this fails */
                                drm_master_put(&priv->minor->master);
                                drm_master_put(&priv->master);
                                mutex_unlock(&dev->struct_mutex);
                                goto out_free;
                        }
                }
                mutex_unlock(&dev->struct_mutex);
        } else {
                /* get a reference to the master */
                priv->master = drm_master_get(priv->minor->master);
                mutex_unlock(&dev->struct_mutex);
        }

        mutex_lock(&dev->struct_mutex);
        list_add(&priv->lhead, &dev->filelist);
        mutex_unlock(&dev->struct_mutex);

#ifdef __alpha__
        /*
         * Default the hose
         */
        if (!dev->hose) {
                struct pci_dev *pci_dev;
                pci_dev = pci_get_class(PCI_CLASS_DISPLAY_VGA << 8, NULL);
                if (pci_dev) {
                        dev->hose = pci_dev->sysdata;
                        pci_dev_put(pci_dev);
                }
                if (!dev->hose) {
                        struct pci_bus *b = pci_bus_b(pci_root_buses.next);
                        if (b)
                                dev->hose = b->sysdata;
                }
        }
#endif

        return 0;
      out_free:
        kfree(priv);
        filp->private_data = NULL;
        return ret;
}

/** No-op. */
int drm_fasync(int fd, struct file *filp, int on)
{
        struct drm_file *priv = filp->private_data;
        struct drm_device *dev = priv->minor->dev;

        DRM_DEBUG("fd = %d, device = 0x%lx\n", fd,
                  (long)old_encode_dev(priv->minor->device));
        return fasync_helper(fd, filp, on, &dev->buf_async);
}
EXPORT_SYMBOL(drm_fasync);

/*
 * Reclaim locked buffers; note that this may be a bad idea if the current
 * context doesn't have the hw lock...
 */
static void drm_reclaim_locked_buffers(struct drm_device *dev, struct file *f)
{
        struct drm_file *file_priv = f->private_data;

        if (drm_i_have_hw_lock(dev, file_priv)) {
                dev->driver->reclaim_buffers_locked(dev, file_priv);
        } else {
                unsigned long _end = jiffies + 3 * DRM_HZ;
                int locked = 0;

                drm_idlelock_take(&file_priv->master->lock);

                /*
                 * Wait for a while.
                 */
                do {
                        spin_lock_bh(&file_priv->master->lock.spinlock);
                        locked = file_priv->master->lock.idle_has_lock;
                        spin_unlock_bh(&file_priv->master->lock.spinlock);
                        if (locked)
                                break;
                        schedule();
                } while (!time_after_eq(jiffies, _end));

                if (!locked) {
                        DRM_ERROR("reclaim_buffers_locked() deadlock. Please rework this\n"
                                  "\tdriver to use reclaim_buffers_idlelocked() instead.\n"
                                  "\tI will go on reclaiming the buffers anyway.\n");
                }

                dev->driver->reclaim_buffers_locked(dev, file_priv);
                drm_idlelock_release(&file_priv->master->lock);
        }
}

static void drm_master_release(struct drm_device *dev, struct file *filp)
{
        struct drm_file *file_priv = filp->private_data;

        if (dev->driver->reclaim_buffers_locked &&
            file_priv->master->lock.hw_lock)
                drm_reclaim_locked_buffers(dev, filp);

        if (dev->driver->reclaim_buffers_idlelocked &&
            file_priv->master->lock.hw_lock) {
                drm_idlelock_take(&file_priv->master->lock);
                dev->driver->reclaim_buffers_idlelocked(dev, file_priv);
                drm_idlelock_release(&file_priv->master->lock);
        }


        if (drm_i_have_hw_lock(dev, file_priv)) {
                DRM_DEBUG("File %p released, freeing lock for context %d\n",
                          filp, _DRM_LOCKING_CONTEXT(file_priv->master->lock.hw_lock->lock));
                drm_lock_free(&file_priv->master->lock,
                              _DRM_LOCKING_CONTEXT(file_priv->master->lock.hw_lock->lock));
        }

        if (drm_core_check_feature(dev, DRIVER_HAVE_DMA) &&
            !dev->driver->reclaim_buffers_locked) {
                dev->driver->reclaim_buffers(dev, file_priv);
        }
}

static void drm_events_release(struct drm_file *file_priv)
{
        struct drm_device *dev = file_priv->minor->dev;
        struct drm_pending_event *e, *et;
        struct drm_pending_vblank_event *v, *vt;
        unsigned long flags;

        spin_lock_irqsave(&dev->event_lock, flags);

        /* Remove pending flips */
        list_for_each_entry_safe(v, vt, &dev->vblank_event_list, base.link)
                if (v->base.file_priv == file_priv) {
                        list_del(&v->base.link);
                        drm_vblank_put(dev, v->pipe);
                        v->base.destroy(&v->base);
                }

        /* Remove unconsumed events */
        list_for_each_entry_safe(e, et, &file_priv->event_list, link)
                e->destroy(e);

        spin_unlock_irqrestore(&dev->event_lock, flags);
}

/**
 * Release file.
 *
 * \param inode device inode
 * \param file_priv DRM file private.
 * \return zero on success or a negative number on failure.
 *
 * If the hardware lock is held then free it, and take it again for the kernel
 * context since it's necessary to reclaim buffers. Unlink the file private
 * data from its list and free it. Decreases the open count and if it reaches
 * zero calls drm_lastclose().
 */
int drm_release(struct inode *inode, struct file *filp)
{
        struct drm_file *file_priv = filp->private_data;
        struct drm_device *dev = file_priv->minor->dev;
        int retcode = 0;

        mutex_lock(&drm_global_mutex);

        DRM_DEBUG("open_count = %d\n", dev->open_count);

        if (dev->driver->preclose)
                dev->driver->preclose(dev, file_priv);

        /* ========================================================
         * Begin inline drm_release
         */

        DRM_DEBUG("pid = %d, device = 0x%lx, open_count = %d\n",
                  task_pid_nr(current),
                  (long)old_encode_dev(file_priv->minor->device),
                  dev->open_count);

        /* if the master has gone away we can't do anything with the lock */
        if (file_priv->minor->master)
                drm_master_release(dev, filp);

        drm_events_release(file_priv);

        if (dev->driver->driver_features & DRIVER_GEM)
                drm_gem_release(dev, file_priv);

        if (dev->driver->driver_features & DRIVER_MODESET)
                drm_fb_release(file_priv);

        mutex_lock(&dev->ctxlist_mutex);
        if (!list_empty(&dev->ctxlist)) {
                struct drm_ctx_list *pos, *n;

                list_for_each_entry_safe(pos, n, &dev->ctxlist, head) {
                        if (pos->tag == file_priv &&
                            pos->handle != DRM_KERNEL_CONTEXT) {
                                if (dev->driver->context_dtor)
                                        dev->driver->context_dtor(dev,
                                                                  pos->handle);

                                drm_ctxbitmap_free(dev, pos->handle);

                                list_del(&pos->head);
                                kfree(pos);
                                --dev->ctx_count;
                        }
                }
        }
        mutex_unlock(&dev->ctxlist_mutex);

        mutex_lock(&dev->struct_mutex);

        if (file_priv->is_master) {
                struct drm_master *master = file_priv->master;
                struct drm_file *temp;
                list_for_each_entry(temp, &dev->filelist, lhead) {
                        if ((temp->master == file_priv->master) &&
                            (temp != file_priv))
                                temp->authenticated = 0;
                }

                /**
                 * Since the master is disappearing, so is the
                 * possibility to lock.
                 */

                if (master->lock.hw_lock) {
                        if (dev->sigdata.lock == master->lock.hw_lock)
                                dev->sigdata.lock = NULL;
                        master->lock.hw_lock = NULL;
                        master->lock.file_priv = NULL;
                        wake_up_interruptible_all(&master->lock.lock_queue);
                }

                if (file_priv->minor->master == file_priv->master) {
                        /* drop the reference held my the minor */
                        if (dev->driver->master_drop)
                                dev->driver->master_drop(dev, file_priv, true);
                        drm_master_put(&file_priv->minor->master);
                }
        }

        /* drop the reference held my the file priv */
        drm_master_put(&file_priv->master);
        file_priv->is_master = 0;
        list_del(&file_priv->lhead);
        mutex_unlock(&dev->struct_mutex);

        if (dev->driver->postclose)
                dev->driver->postclose(dev, file_priv);
        kfree(file_priv);

        /* ========================================================
         * End inline drm_release
         */

        atomic_inc(&dev->counts[_DRM_STAT_CLOSES]);
        if (!--dev->open_count) {
                if (atomic_read(&dev->ioctl_count)) {
                        DRM_ERROR("Device busy: %d\n",
                                  atomic_read(&dev->ioctl_count));
                        retcode = -EBUSY;
                } else
                        retcode = drm_lastclose(dev);
        }
        mutex_unlock(&drm_global_mutex);

        return retcode;
}
EXPORT_SYMBOL(drm_release);

static bool
drm_dequeue_event(struct drm_file *file_priv,
                  size_t total, size_t max, struct drm_pending_event **out)
{
        struct drm_device *dev = file_priv->minor->dev;
        struct drm_pending_event *e;
        unsigned long flags;
        bool ret = false;

        spin_lock_irqsave(&dev->event_lock, flags);

        *out = NULL;
        if (list_empty(&file_priv->event_list))
                goto out;
        e = list_first_entry(&file_priv->event_list,
                             struct drm_pending_event, link);
        if (e->event->length + total > max)
                goto out;

        file_priv->event_space += e->event->length;
        list_del(&e->link);
        *out = e;
        ret = true;

out:
        spin_unlock_irqrestore(&dev->event_lock, flags);
        return ret;
}

ssize_t drm_read(struct file *filp, char __user *buffer,
                 size_t count, loff_t *offset)
{
        struct drm_file *file_priv = filp->private_data;
        struct drm_pending_event *e;
        size_t total;
        ssize_t ret;

        ret = wait_event_interruptible(file_priv->event_wait,
                                       !list_empty(&file_priv->event_list));
        if (ret < 0)
                return ret;

        total = 0;
        while (drm_dequeue_event(file_priv, total, count, &e)) {
                if (copy_to_user(buffer + total,
                                 e->event, e->event->length)) {
                        total = -EFAULT;
                        break;
                }

                total += e->event->length;
                e->destroy(e);
        }

        return total;
}
EXPORT_SYMBOL(drm_read);

unsigned int drm_poll(struct file *filp, struct poll_table_struct *wait)
{
        struct drm_file *file_priv = filp->private_data;
        unsigned int mask = 0;

        poll_wait(filp, &file_priv->event_wait, wait);

        if (!list_empty(&file_priv->event_list))
                mask |= POLLIN | POLLRDNORM;

        return mask;
}
EXPORT_SYMBOL(drm_poll);