/**
 * \file drm_context.h 
 * IOCTLs for generic contexts
 * 
 * \author Rickard E. (Rik) Faith <faith@valinux.com>
 * \author Gareth Hughes <gareth@valinux.com>
 */

/*
 * Created: Fri Nov 24 18:31:37 2000 by gareth@valinux.com
 *
 * Copyright 1999, 2000 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.
 */

/*
 * ChangeLog:
 *  2001-11-16  Torsten Duwe <duwe@caldera.de>
 *              added context constructor/destructor hooks,
 *              needed by SiS driver's memory management.
 */

#include "drmP.h"

/******************************************************************/
/** \name Context bitmap support */
/*@{*/

/**
 * Free a handle from the context bitmap.
 *
 * \param dev DRM device.
 * \param ctx_handle context handle.
 *
 * Clears the bit specified by \p ctx_handle in drm_device::ctx_bitmap and the entry
 * in drm_device::context_sareas, while holding the drm_device::struct_sem
 * lock.
 */
void drm_ctxbitmap_free( drm_device_t *dev, int ctx_handle )
{
        if ( ctx_handle < 0 ) goto failed;
        if ( !dev->ctx_bitmap ) goto failed;

        if ( ctx_handle < DRM_MAX_CTXBITMAP ) {
                down(&dev->struct_sem);
                clear_bit( ctx_handle, dev->ctx_bitmap );
                dev->context_sareas[ctx_handle] = NULL;
                up(&dev->struct_sem);
                return;
        }
failed:
        DRM_ERROR( "Attempt to free invalid context handle: %d\n",
                   ctx_handle );
        return;
}

/** 
 * Context bitmap allocation.
 *
 * \param dev DRM device.
 * \return (non-negative) context handle on success or a negative number on failure.
 *
 * Find the first zero bit in drm_device::ctx_bitmap and (re)allocates
 * drm_device::context_sareas to accommodate the new entry while holding the
 * drm_device::struct_sem lock.
 */
int drm_ctxbitmap_next( drm_device_t *dev )
{
        int bit;

        if(!dev->ctx_bitmap) return -1;

        down(&dev->struct_sem);
        bit = find_first_zero_bit( dev->ctx_bitmap, DRM_MAX_CTXBITMAP );
        if ( bit < DRM_MAX_CTXBITMAP ) {
                set_bit( bit, dev->ctx_bitmap );
                DRM_DEBUG( "drm_ctxbitmap_next bit : %d\n", bit );
                if((bit+1) > dev->max_context) {
                        dev->max_context = (bit+1);
                        if(dev->context_sareas) {
                                drm_map_t **ctx_sareas;

                                ctx_sareas = drm_realloc(dev->context_sareas,
                                                (dev->max_context - 1) * 
                                                sizeof(*dev->context_sareas),
                                                dev->max_context * 
                                                sizeof(*dev->context_sareas),
                                                DRM_MEM_MAPS);
                                if(!ctx_sareas) {
                                        clear_bit(bit, dev->ctx_bitmap);
                                        up(&dev->struct_sem);
                                        return -1;
                                }
                                dev->context_sareas = ctx_sareas;
                                dev->context_sareas[bit] = NULL;
                        } else {
                                /* max_context == 1 at this point */
                                dev->context_sareas = drm_alloc(
                                                dev->max_context * 
                                                sizeof(*dev->context_sareas),
                                                DRM_MEM_MAPS);
                                if(!dev->context_sareas) {
                                        clear_bit(bit, dev->ctx_bitmap);
                                        up(&dev->struct_sem);
                                        return -1;
                                }
                                dev->context_sareas[bit] = NULL;
                        }
                }
                up(&dev->struct_sem);
                return bit;
        }
        up(&dev->struct_sem);
        return -1;
}

/**
 * Context bitmap initialization.
 *
 * \param dev DRM device.
 *
 * Allocates and initialize drm_device::ctx_bitmap and drm_device::context_sareas, while holding
 * the drm_device::struct_sem lock.
 */
int drm_ctxbitmap_init( drm_device_t *dev )
{
        int i;
        int temp;

        down(&dev->struct_sem);
        dev->ctx_bitmap = (unsigned long *) drm_alloc( PAGE_SIZE,
                                                        DRM_MEM_CTXBITMAP );
        if ( dev->ctx_bitmap == NULL ) {
                up(&dev->struct_sem);
                return -ENOMEM;
        }
        memset( (void *)dev->ctx_bitmap, 0, PAGE_SIZE );
        dev->context_sareas = NULL;
        dev->max_context = -1;
        up(&dev->struct_sem);

        for ( i = 0 ; i < DRM_RESERVED_CONTEXTS ; i++ ) {
                temp = drm_ctxbitmap_next( dev );
                DRM_DEBUG( "drm_ctxbitmap_init : %d\n", temp );
        }

        return 0;
}

/**
 * Context bitmap cleanup.
 *
 * \param dev DRM device.
 *
 * Frees drm_device::ctx_bitmap and drm_device::context_sareas, while holding
 * the drm_device::struct_sem lock.
 */
void drm_ctxbitmap_cleanup( drm_device_t *dev )
{
        down(&dev->struct_sem);
        if( dev->context_sareas ) drm_free( dev->context_sareas,
                                             sizeof(*dev->context_sareas) * 
                                             dev->max_context,
                                             DRM_MEM_MAPS );
        drm_free( (void *)dev->ctx_bitmap, PAGE_SIZE, DRM_MEM_CTXBITMAP );
        up(&dev->struct_sem);
}

/*@}*/

/******************************************************************/
/** \name Per Context SAREA Support */
/*@{*/

/**
 * Get per-context SAREA.
 * 
 * \param inode device inode.
 * \param filp file pointer.
 * \param cmd command.
 * \param arg user argument pointing to a drm_ctx_priv_map structure.
 * \return zero on success or a negative number on failure.
 *
 * Gets the map from drm_device::context_sareas with the handle specified and
 * returns its handle.
 */
int drm_getsareactx(struct inode *inode, struct file *filp,
                     unsigned int cmd, unsigned long arg)
{
        drm_file_t      *priv   = filp->private_data;
        drm_device_t    *dev    = priv->dev;
        drm_ctx_priv_map_t __user *argp = (void __user *)arg;
        drm_ctx_priv_map_t request;
        drm_map_t *map;

        if (copy_from_user(&request, argp, sizeof(request)))
                return -EFAULT;

        down(&dev->struct_sem);
        if (dev->max_context < 0 || request.ctx_id >= (unsigned) dev->max_context) {
                up(&dev->struct_sem);
                return -EINVAL;
        }

        map = dev->context_sareas[request.ctx_id];
        up(&dev->struct_sem);

        request.handle = map->handle;
        if (copy_to_user(argp, &request, sizeof(request)))
                return -EFAULT;
        return 0;
}

/**
 * Set per-context SAREA.
 * 
 * \param inode device inode.
 * \param filp file pointer.
 * \param cmd command.
 * \param arg user argument pointing to a drm_ctx_priv_map structure.
 * \return zero on success or a negative number on failure.
 *
 * Searches the mapping specified in \p arg and update the entry in
 * drm_device::context_sareas with it.
 */
int drm_setsareactx(struct inode *inode, struct file *filp,
                     unsigned int cmd, unsigned long arg)
{
        drm_file_t      *priv   = filp->private_data;
        drm_device_t    *dev    = priv->dev;
        drm_ctx_priv_map_t request;
        drm_map_t *map = NULL;
        drm_map_list_t *r_list = NULL;
        struct list_head *list;

        if (copy_from_user(&request,
                           (drm_ctx_priv_map_t __user *)arg,
                           sizeof(request)))
                return -EFAULT;

        down(&dev->struct_sem);
        list_for_each(list, &dev->maplist->head) {
                r_list = list_entry(list, drm_map_list_t, head);
                if(r_list->map &&
                   r_list->map->handle == request.handle)
                        goto found;
        }
bad:
        up(&dev->struct_sem);
        return -EINVAL;

found:
        map = r_list->map;
        if (!map) goto bad;
        if (dev->max_context < 0)
                goto bad;
        if (request.ctx_id >= (unsigned) dev->max_context)
                goto bad;
        dev->context_sareas[request.ctx_id] = map;
        up(&dev->struct_sem);
        return 0;
}

/*@}*/

/******************************************************************/
/** \name The actual DRM context handling routines */
/*@{*/

/**
 * Switch context.
 *
 * \param dev DRM device.
 * \param old old context handle.
 * \param new new context handle.
 * \return zero on success or a negative number on failure.
 *
 * Attempt to set drm_device::context_flag.
 */
int drm_context_switch( drm_device_t *dev, int old, int new )
{
        if ( test_and_set_bit( 0, &dev->context_flag ) ) {
                DRM_ERROR( "Reentering -- FIXME\n" );
                return -EBUSY;
        }


        DRM_DEBUG( "Context switch from %d to %d\n", old, new );

        if ( new == dev->last_context ) {
                clear_bit( 0, &dev->context_flag );
                return 0;
        }

        return 0;
}

/**
 * Complete context switch.
 *
 * \param dev DRM device.
 * \param new new context handle.
 * \return zero on success or a negative number on failure.
 *
 * Updates drm_device::last_context and drm_device::last_switch. Verifies the
 * hardware lock is held, clears the drm_device::context_flag and wakes up
 * drm_device::context_wait.
 */
int drm_context_switch_complete( drm_device_t *dev, int new )
{
        dev->last_context = new;  /* PRE/POST: This is the _only_ writer. */
        dev->last_switch  = jiffies;

        if ( !_DRM_LOCK_IS_HELD(dev->lock.hw_lock->lock) ) {
                DRM_ERROR( "Lock isn't held after context switch\n" );
        }

                                /* If a context switch is ever initiated
                                   when the kernel holds the lock, release
                                   that lock here. */
        clear_bit( 0, &dev->context_flag );
        wake_up( &dev->context_wait );

        return 0;
}

/**
 * Reserve contexts.
 *
 * \param inode device inode.
 * \param filp file pointer.
 * \param cmd command.
 * \param arg user argument pointing to a drm_ctx_res structure.
 * \return zero on success or a negative number on failure.
 */
int drm_resctx( struct inode *inode, struct file *filp,
                 unsigned int cmd, unsigned long arg )
{
        drm_ctx_res_t res;
        drm_ctx_t __user *argp = (void __user *)arg;
        drm_ctx_t ctx;
        int i;

        if ( copy_from_user( &res, argp, sizeof(res) ) )
                return -EFAULT;

        if ( res.count >= DRM_RESERVED_CONTEXTS ) {
                memset( &ctx, 0, sizeof(ctx) );
                for ( i = 0 ; i < DRM_RESERVED_CONTEXTS ; i++ ) {
                        ctx.handle = i;
                        if ( copy_to_user( &res.contexts[i],
                                           &i, sizeof(i) ) )
                                return -EFAULT;
                }
        }
        res.count = DRM_RESERVED_CONTEXTS;

        if ( copy_to_user( argp, &res, sizeof(res) ) )
                return -EFAULT;
        return 0;
}

/**
 * Add context.
 *
 * \param inode device inode.
 * \param filp file pointer.
 * \param cmd command.
 * \param arg user argument pointing to a drm_ctx structure.
 * \return zero on success or a negative number on failure.
 *
 * Get a new handle for the context and copy to userspace.
 */
int drm_addctx( struct inode *inode, struct file *filp,
                 unsigned int cmd, unsigned long arg )
{
        drm_file_t *priv = filp->private_data;
        drm_device_t *dev = priv->dev;
        drm_ctx_list_t * ctx_entry;
        drm_ctx_t __user *argp = (void __user *)arg;
        drm_ctx_t ctx;

        if ( copy_from_user( &ctx, argp, sizeof(ctx) ) )
                return -EFAULT;

        ctx.handle = drm_ctxbitmap_next( dev );
        if ( ctx.handle == DRM_KERNEL_CONTEXT ) {
                                /* Skip kernel's context and get a new one. */
                ctx.handle = drm_ctxbitmap_next( dev );
        }
        DRM_DEBUG( "%d\n", ctx.handle );
        if ( ctx.handle == -1 ) {
                DRM_DEBUG( "Not enough free contexts.\n" );
                                /* Should this return -EBUSY instead? */
                return -ENOMEM;
        }

        if ( ctx.handle != DRM_KERNEL_CONTEXT )
        {
                if (dev->driver->context_ctor)
                        dev->driver->context_ctor(dev, ctx.handle);
        }

        ctx_entry = drm_alloc( sizeof(*ctx_entry), DRM_MEM_CTXLIST );
        if ( !ctx_entry ) {
                DRM_DEBUG("out of memory\n");
                return -ENOMEM;
        }

        INIT_LIST_HEAD( &ctx_entry->head );
        ctx_entry->handle = ctx.handle;
        ctx_entry->tag = priv;

        down( &dev->ctxlist_sem );
        list_add( &ctx_entry->head, &dev->ctxlist->head );
        ++dev->ctx_count;
        up( &dev->ctxlist_sem );

        if ( copy_to_user( argp, &ctx, sizeof(ctx) ) )
                return -EFAULT;
        return 0;
}

int drm_modctx( struct inode *inode, struct file *filp,
                 unsigned int cmd, unsigned long arg )
{
        /* This does nothing */
        return 0;
}

/**
 * Get context.
 *
 * \param inode device inode.
 * \param filp file pointer.
 * \param cmd command.
 * \param arg user argument pointing to a drm_ctx structure.
 * \return zero on success or a negative number on failure.
 */
int drm_getctx( struct inode *inode, struct file *filp,
                 unsigned int cmd, unsigned long arg )
{
        drm_ctx_t __user *argp = (void __user *)arg;
        drm_ctx_t ctx;

        if ( copy_from_user( &ctx, argp, sizeof(ctx) ) )
                return -EFAULT;

        /* This is 0, because we don't handle any context flags */
        ctx.flags = 0;

        if ( copy_to_user( argp, &ctx, sizeof(ctx) ) )
                return -EFAULT;
        return 0;
}

/**
 * Switch context.
 *
 * \param inode device inode.
 * \param filp file pointer.
 * \param cmd command.
 * \param arg user argument pointing to a drm_ctx structure.
 * \return zero on success or a negative number on failure.
 *
 * Calls context_switch().
 */
int drm_switchctx( struct inode *inode, struct file *filp,
                    unsigned int cmd, unsigned long arg )
{
        drm_file_t *priv = filp->private_data;
        drm_device_t *dev = priv->dev;
        drm_ctx_t ctx;

        if ( copy_from_user( &ctx, (drm_ctx_t __user *)arg, sizeof(ctx) ) )
                return -EFAULT;

        DRM_DEBUG( "%d\n", ctx.handle );
        return drm_context_switch( dev, dev->last_context, ctx.handle );
}

/**
 * New context.
 *
 * \param inode device inode.
 * \param filp file pointer.
 * \param cmd command.
 * \param arg user argument pointing to a drm_ctx structure.
 * \return zero on success or a negative number on failure.
 *
 * Calls context_switch_complete().
 */
int drm_newctx( struct inode *inode, struct file *filp,
                 unsigned int cmd, unsigned long arg )
{
        drm_file_t *priv = filp->private_data;
        drm_device_t *dev = priv->dev;
        drm_ctx_t ctx;

        if ( copy_from_user( &ctx, (drm_ctx_t __user *)arg, sizeof(ctx) ) )
                return -EFAULT;

        DRM_DEBUG( "%d\n", ctx.handle );
        drm_context_switch_complete( dev, ctx.handle );

        return 0;
}

/**
 * Remove context.
 *
 * \param inode device inode.
 * \param filp file pointer.
 * \param cmd command.
 * \param arg user argument pointing to a drm_ctx structure.
 * \return zero on success or a negative number on failure.
 *
 * If not the special kernel context, calls ctxbitmap_free() to free the specified context.
 */
int drm_rmctx( struct inode *inode, struct file *filp,
                unsigned int cmd, unsigned long arg )
{
        drm_file_t *priv = filp->private_data;
        drm_device_t *dev = priv->dev;
        drm_ctx_t ctx;

        if ( copy_from_user( &ctx, (drm_ctx_t __user *)arg, sizeof(ctx) ) )
                return -EFAULT;

        DRM_DEBUG( "%d\n", ctx.handle );
        if ( ctx.handle == DRM_KERNEL_CONTEXT + 1 ) {
                priv->remove_auth_on_close = 1;
        }
        if ( ctx.handle != DRM_KERNEL_CONTEXT ) {
                if (dev->driver->context_dtor)
                        dev->driver->context_dtor(dev, ctx.handle);
                drm_ctxbitmap_free( dev, ctx.handle );
        }

        down( &dev->ctxlist_sem );
        if ( !list_empty( &dev->ctxlist->head ) ) {
                drm_ctx_list_t *pos, *n;

                list_for_each_entry_safe( pos, n, &dev->ctxlist->head, head ) {
                        if ( pos->handle == ctx.handle ) {
                                list_del( &pos->head );
                                drm_free( pos, sizeof(*pos), DRM_MEM_CTXLIST );
                                --dev->ctx_count;
                        }
                }
        }
        up( &dev->ctxlist_sem );

        return 0;
}

/*@}*/