/* fops.c -- File operations for DRM -*- linux-c -*-
 * Created: Mon Jan  4 08:58:31 1999 by faith@precisioninsight.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
 * PRECISION INSIGHT 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.
 * 
 * Authors:
 *    Rickard E. (Rik) Faith <faith@valinux.com>
 *    Daryll Strauss <daryll@valinux.com>
 *
 */

#define __NO_VERSION__
#include "drmP.h"
#include <linux/poll.h>

/* drm_open is called whenever a process opens /dev/drm. */

int drm_open_helper(struct inode *inode, struct file *filp, drm_device_t *dev)
{
        kdev_t       minor = MINOR(inode->i_rdev);
        drm_file_t   *priv;

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

        DRM_DEBUG("pid = %d, minor = %d\n", current->pid, minor);

        priv                = drm_alloc(sizeof(*priv), DRM_MEM_FILES);
        if(priv == NULL)
                return -ENOMEM;
        memset(priv, 0, sizeof(*priv));

        filp->private_data  = priv;
        priv->uid           = current->euid;
        priv->pid           = current->pid;
        priv->minor         = minor;
        priv->dev           = dev;
        priv->ioctl_count   = 0;
        priv->authenticated = capable(CAP_SYS_ADMIN);

        down(&dev->struct_sem);
        if (!dev->file_last) {
                priv->next      = NULL;
                priv->prev      = NULL;
                dev->file_first = priv;
                dev->file_last  = priv;
        } else {
                priv->next           = NULL;
                priv->prev           = dev->file_last;
                dev->file_last->next = priv;
                dev->file_last       = priv;
        }
        up(&dev->struct_sem);
        
        return 0;
}

int drm_flush(struct file *filp)
{
        drm_file_t    *priv   = filp->private_data;
        drm_device_t  *dev    = priv->dev;

        DRM_DEBUG("pid = %d, device = 0x%x, open_count = %d\n",
                  current->pid, dev->device, dev->open_count);
        return 0;
}

/* drm_release is called whenever a process closes /dev/drm*.  Linux calls
   this only if any mappings have been closed. */

int drm_release(struct inode *inode, struct file *filp)
{
        drm_file_t    *priv   = filp->private_data;
        drm_device_t  *dev    = priv->dev;

        DRM_DEBUG("pid = %d, device = 0x%x, open_count = %d\n",
                  current->pid, dev->device, dev->open_count);

        if (dev->lock.hw_lock
            && _DRM_LOCK_IS_HELD(dev->lock.hw_lock->lock)
            && dev->lock.pid == current->pid) {
                DRM_ERROR("Process %d dead, freeing lock for context %d\n",
                          current->pid,
                          _DRM_LOCKING_CONTEXT(dev->lock.hw_lock->lock));
                drm_lock_free(dev,
                              &dev->lock.hw_lock->lock,
                              _DRM_LOCKING_CONTEXT(dev->lock.hw_lock->lock));
                
                                /* FIXME: may require heavy-handed reset of
                                   hardware at this point, possibly
                                   processed via a callback to the X
                                   server. */
        }
        drm_reclaim_buffers(dev, priv->pid);

        drm_fasync(-1, filp, 0);

        down(&dev->struct_sem);
        if (priv->prev) priv->prev->next = priv->next;
        else            dev->file_first  = priv->next;
        if (priv->next) priv->next->prev = priv->prev;
        else            dev->file_last   = priv->prev;
        up(&dev->struct_sem);
        
        drm_free(priv, sizeof(*priv), DRM_MEM_FILES);
        
        return 0;
}

int drm_fasync(int fd, struct file *filp, int on)
{
        drm_file_t    *priv   = filp->private_data;
        drm_device_t  *dev    = priv->dev;
        int           retcode;
        
        DRM_DEBUG("fd = %d, device = 0x%x\n", fd, dev->device);
        retcode = fasync_helper(fd, filp, on, &dev->buf_async);
        if (retcode < 0) return retcode;
        return 0;
}


/* The drm_read and drm_write_string code (especially that which manages
   the circular buffer), is based on Alessandro Rubini's LINUX DEVICE
   DRIVERS (Cambridge: O'Reilly, 1998), pages 111-113. */

ssize_t drm_read(struct file *filp, char *buf, size_t count, loff_t *off)
{
        drm_file_t    *priv   = filp->private_data;
        drm_device_t  *dev    = priv->dev;
        int           left;
        int           avail;
        int           send;
        int           cur;

        DRM_DEBUG("%p, %p\n", dev->buf_rp, dev->buf_wp);
        
        while (dev->buf_rp == dev->buf_wp) {
                DRM_DEBUG("  sleeping\n");
                if (filp->f_flags & O_NONBLOCK) {
                        return -EAGAIN;
                }
                interruptible_sleep_on(&dev->buf_readers);
                if (signal_pending(current)) {
                        DRM_DEBUG("  interrupted\n");
                        return -ERESTARTSYS;
                }
                DRM_DEBUG("  awake\n");
        }

        left  = (dev->buf_rp + DRM_BSZ - dev->buf_wp) % DRM_BSZ;
        avail = DRM_BSZ - left;
        send  = DRM_MIN(avail, count);

        while (send) {
                if (dev->buf_wp > dev->buf_rp) {
                        cur = DRM_MIN(send, dev->buf_wp - dev->buf_rp);
                } else {
                        cur = DRM_MIN(send, dev->buf_end - dev->buf_rp);
                }
                if (copy_to_user(buf, dev->buf_rp, cur))
                        return -EFAULT;
                dev->buf_rp += cur;
                if (dev->buf_rp == dev->buf_end) dev->buf_rp = dev->buf;
                send -= cur;
        }
        
        wake_up_interruptible(&dev->buf_writers);
        return DRM_MIN(avail, count);;
}

int drm_write_string(drm_device_t *dev, const char *s)
{
        int left   = (dev->buf_rp + DRM_BSZ - dev->buf_wp) % DRM_BSZ;
        int send   = strlen(s);
        int count;

        DRM_DEBUG("%d left, %d to send (%p, %p)\n",
                  left, send, dev->buf_rp, dev->buf_wp);
        
        if (left == 1 || dev->buf_wp != dev->buf_rp) {
                DRM_ERROR("Buffer not empty (%d left, wp = %p, rp = %p)\n",
                          left,
                          dev->buf_wp,
                          dev->buf_rp);
        }

        while (send) {
                if (dev->buf_wp >= dev->buf_rp) {
                        count = DRM_MIN(send, dev->buf_end - dev->buf_wp);
                        if (count == left) --count; /* Leave a hole */
                } else {
                        count = DRM_MIN(send, dev->buf_rp - dev->buf_wp - 1);
                }
                strncpy(dev->buf_wp, s, count);
                dev->buf_wp += count;
                if (dev->buf_wp == dev->buf_end) dev->buf_wp = dev->buf;
                send -= count;
        }

#if LINUX_VERSION_CODE < 0x020315 && !defined(KILLFASYNCHASTHREEPARAMETERS)
        /* The extra parameter to kill_fasync was added in 2.3.21, and is
           _not_ present in _stock_ 2.2.14 and 2.2.15.  However, some
           distributions patch 2.2.x kernels to add this parameter.  The
           Makefile.linux attempts to detect this addition and defines
           KILLFASYNCHASTHREEPARAMETERS if three parameters are found. */
        if (dev->buf_async) kill_fasync(dev->buf_async, SIGIO);
#else

                                /* Parameter added in 2.3.21. */
#if LINUX_VERSION_CODE < 0x020400
        if (dev->buf_async) kill_fasync(dev->buf_async, SIGIO, POLL_IN);
#else
                                /* Type of first parameter changed in
                                   Linux 2.4.0-test2... */
        if (dev->buf_async) kill_fasync(&dev->buf_async, SIGIO, POLL_IN);
#endif
#endif
        DRM_DEBUG("waking\n");
        wake_up_interruptible(&dev->buf_readers);
        return 0;
}

unsigned int drm_poll(struct file *filp, struct poll_table_struct *wait)
{
        drm_file_t   *priv = filp->private_data;
        drm_device_t *dev  = priv->dev;

        poll_wait(filp, &dev->buf_readers, wait);
        if (dev->buf_wp != dev->buf_rp) return POLLIN | POLLRDNORM;
        return 0;
}