/* drm_fops.h -- File operations for DRM -*- linux-c -*-
 * 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.
 *
 * Authors:
 *    Rickard E. (Rik) Faith <faith@valinux.com>
 *    Daryll Strauss <daryll@valinux.com>
 *    Gareth Hughes <gareth@valinux.com>
 */

#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)
{
        int          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) 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);

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

        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%lx, open_count = %d\n",
                  current->pid, (long)dev->device, dev->open_count);
        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%lx\n", fd, (long)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;
        DECLARE_WAITQUEUE(wait, current);

        DRM_DEBUG("%p, %p\n", dev->buf_rp, dev->buf_wp);

        add_wait_queue(&dev->buf_readers, &wait);
        set_current_state(TASK_INTERRUPTIBLE);
        while (dev->buf_rp == dev->buf_wp) {
                DRM_DEBUG("  sleeping\n");
                if (filp->f_flags & O_NONBLOCK) {
                        remove_wait_queue(&dev->buf_readers, &wait);
                        set_current_state(TASK_RUNNING);
                        return -EAGAIN;
                }
                schedule(); /* wait for dev->buf_readers */
                if (signal_pending(current)) {
                        DRM_DEBUG("  interrupted\n");
                        remove_wait_queue(&dev->buf_readers, &wait);
                        set_current_state(TASK_RUNNING);
                        return -ERESTARTSYS;
                }
                DRM_DEBUG("  awake\n");
                set_current_state(TASK_INTERRUPTIBLE);
        }
        remove_wait_queue(&dev->buf_readers, &wait);
        set_current_state(TASK_RUNNING);

        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 (dev->buf_async) kill_fasync(&dev->buf_async, SIGIO, POLL_IN);

        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;
}