drm_vm.c

底层驱动开发

static struct page *drm_vm_shm_nopage(struct vm_area_struct *vma,
				       unsigned long address,
				       int *type) {
	if (type) *type = VM_FAULT_MINOR;
	return drm_do_vm_shm_nopage(vma, address);
}

static struct page *drm_vm_dma_nopage(struct vm_area_struct *vma,
				       unsigned long address,
				       int *type) {
	if (type) *type = VM_FAULT_MINOR;
	return drm_do_vm_dma_nopage(vma, address);
}

static struct page *drm_vm_sg_nopage(struct vm_area_struct *vma,
				      unsigned long address,
				      int *type) {
	if (type) *type = VM_FAULT_MINOR;
	return drm_do_vm_sg_nopage(vma, address);
}

/** AGP virtual memory operations */
static struct vm_operations_struct   drm_vm_ops = {
	.nopage = drm_vm_nopage,
	.open	= drm_vm_open,
	.close	= drm_vm_close,
};

/** Shared virtual memory operations */
static struct vm_operations_struct   drm_vm_shm_ops = {
	.nopage = drm_vm_shm_nopage,
	.open	= drm_vm_open,
	.close	= drm_vm_shm_close,
};

/** DMA virtual memory operations */
static struct vm_operations_struct   drm_vm_dma_ops = {
	.nopage = drm_vm_dma_nopage,
	.open	= drm_vm_open,
	.close	= drm_vm_close,
};

/** Scatter-gather virtual memory operations */
static struct vm_operations_struct   drm_vm_sg_ops = {
	.nopage = drm_vm_sg_nopage,
	.open   = drm_vm_open,
	.close  = drm_vm_close,
};


/**
 * \c open method for shared virtual memory.
 * 
 * \param vma virtual memory area.
 * 
 * Create a new drm_vma_entry structure as the \p vma private data entry and
 * add it to drm_device::vmalist.
 */
static void drm_vm_open(struct vm_area_struct *vma)
{
	drm_file_t	*priv	= vma->vm_file->private_data;
	drm_device_t	*dev	= priv->head->dev;
	drm_vma_entry_t *vma_entry;

	DRM_DEBUG("0x%08lx,0x%08lx\n",
		  vma->vm_start, vma->vm_end - vma->vm_start);
	atomic_inc(&dev->vma_count);

	vma_entry = drm_alloc(sizeof(*vma_entry), DRM_MEM_VMAS);
	if (vma_entry) {
		down(&dev->struct_sem);
		vma_entry->vma	= vma;
		vma_entry->next = dev->vmalist;
		vma_entry->pid	= current->pid;
		dev->vmalist	= vma_entry;
		up(&dev->struct_sem);
	}
}

/**
 * \c close method for all virtual memory types.
 * 
 * \param vma virtual memory area.
 * 
 * Search the \p vma private data entry in drm_device::vmalist, unlink it, and
 * free it.
 */
static void drm_vm_close(struct vm_area_struct *vma)
{
	drm_file_t	*priv	= vma->vm_file->private_data;
	drm_device_t	*dev	= priv->head->dev;
	drm_vma_entry_t *pt, *prev;

	DRM_DEBUG("0x%08lx,0x%08lx\n",
		  vma->vm_start, vma->vm_end - vma->vm_start);
	atomic_dec(&dev->vma_count);

	down(&dev->struct_sem);
	for (pt = dev->vmalist, prev = NULL; pt; prev = pt, pt = pt->next) {
		if (pt->vma == vma) {
			if (prev) {
				prev->next = pt->next;
			} else {
				dev->vmalist = pt->next;
			}
			drm_free(pt, sizeof(*pt), DRM_MEM_VMAS);
			break;
		}
	}
	up(&dev->struct_sem);
}

/**
 * mmap DMA memory.
 *
 * \param filp file pointer.
 * \param vma virtual memory area.
 * \return zero on success or a negative number on failure.
 * 
 * Sets the virtual memory area operations structure to vm_dma_ops, the file
 * pointer, and calls vm_open().
 */
static int drm_mmap_dma(struct file *filp, struct vm_area_struct *vma)
{
	drm_file_t	 *priv	 = filp->private_data;
	drm_device_t	 *dev;
	drm_device_dma_t *dma;
	unsigned long	 length	 = vma->vm_end - vma->vm_start;

	lock_kernel();
	dev	 = priv->head->dev;
	dma	 = dev->dma;
	DRM_DEBUG("start = 0x%lx, end = 0x%lx, offset = 0x%lx\n",
		  vma->vm_start, vma->vm_end, VM_OFFSET(vma));

				/* Length must match exact page count */
	if (!dma || (length >> PAGE_SHIFT) != dma->page_count) {
		unlock_kernel();
		return -EINVAL;
	}
	unlock_kernel();

	vma->vm_ops   = &drm_vm_dma_ops;

	vma->vm_flags |= VM_RESERVED; /* Don't swap */

	vma->vm_file  =	 filp;	/* Needed for drm_vm_open() */
	drm_vm_open(vma);
	return 0;
}

unsigned long drm_core_get_map_ofs(drm_map_t *map)
{
	return map->offset;
}
EXPORT_SYMBOL(drm_core_get_map_ofs);

unsigned long drm_core_get_reg_ofs(struct drm_device *dev)
{
#ifdef __alpha__
	return dev->hose->dense_mem_base - dev->hose->mem_space->start;
#else
	return 0;
#endif
}
EXPORT_SYMBOL(drm_core_get_reg_ofs);

/**
 * mmap DMA memory.
 *
 * \param filp file pointer.
 * \param vma virtual memory area.
 * \return zero on success or a negative number on failure.
 * 
 * If the virtual memory area has no offset associated with it then it's a DMA
 * area, so calls mmap_dma(). Otherwise searches the map in drm_device::maplist,
 * checks that the restricted flag is not set, sets the virtual memory operations
 * according to the mapping type and remaps the pages. Finally sets the file
 * pointer and calls vm_open().
 */
int drm_mmap(struct file *filp, struct vm_area_struct *vma)
{
	drm_file_t	*priv	= filp->private_data;
	drm_device_t	*dev	= priv->head->dev;
	drm_map_t	*map	= NULL;
	drm_map_list_t  *r_list;
	unsigned long   offset  = 0;
	struct list_head *list;

	DRM_DEBUG("start = 0x%lx, end = 0x%lx, offset = 0x%lx\n",
		  vma->vm_start, vma->vm_end, VM_OFFSET(vma));

	if ( !priv->authenticated ) return -EACCES;

	/* We check for "dma". On Apple's UniNorth, it's valid to have
	 * the AGP mapped at physical address 0
	 * --BenH.
	 */
	if (!VM_OFFSET(vma)
#if __OS_HAS_AGP
	    && (!dev->agp || dev->agp->agp_info.device->vendor != PCI_VENDOR_ID_APPLE)
#endif
	    )
		return drm_mmap_dma(filp, vma);

				/* A sequential search of a linked list is
				   fine here because: 1) there will only be
				   about 5-10 entries in the list and, 2) a
				   DRI client only has to do this mapping
				   once, so it doesn't have to be optimized
				   for performance, even if the list was a
				   bit longer. */
	list_for_each(list, &dev->maplist->head) {

		r_list = list_entry(list, drm_map_list_t, head);
		map = r_list->map;
		if (!map) continue;
		if (r_list->user_token == VM_OFFSET(vma))
			break;
	}

	if (!map || ((map->flags&_DRM_RESTRICTED) && !capable(CAP_SYS_ADMIN)))
		return -EPERM;

				/* Check for valid size. */
	if (map->size != vma->vm_end - vma->vm_start) return -EINVAL;

	if (!capable(CAP_SYS_ADMIN) && (map->flags & _DRM_READ_ONLY)) {
		vma->vm_flags &= ~(VM_WRITE | VM_MAYWRITE);
#if defined(__i386__) || defined(__x86_64__)
		pgprot_val(vma->vm_page_prot) &= ~_PAGE_RW;
#else
				/* Ye gads this is ugly.  With more thought
                                   we could move this up higher and use
                                   `protection_map' instead.  */
		vma->vm_page_prot = __pgprot(pte_val(pte_wrprotect(
			__pte(pgprot_val(vma->vm_page_prot)))));
#endif
	}

	switch (map->type) {
        case _DRM_AGP:
	  if (drm_core_has_AGP(dev) && dev->agp->cant_use_aperture) {
                /*
                 * On some platforms we can't talk to bus dma address from the CPU, so for
                 * memory of type DRM_AGP, we'll deal with sorting out the real physical
                 * pages and mappings in nopage()
                 */
#if defined(__powerpc__)
		pgprot_val(vma->vm_page_prot) |= _PAGE_NO_CACHE;
#endif
                vma->vm_ops = &drm_vm_ops;
                break;
	  }
                /* fall through to _DRM_FRAME_BUFFER... */        
	case _DRM_FRAME_BUFFER:
	case _DRM_REGISTERS:
#if defined(__i386__) || defined(__x86_64__)
		if (boot_cpu_data.x86 > 3 && map->type != _DRM_AGP) {
			pgprot_val(vma->vm_page_prot) |= _PAGE_PCD;
			pgprot_val(vma->vm_page_prot) &= ~_PAGE_PWT;
		}
#elif defined(__powerpc__)
		pgprot_val(vma->vm_page_prot) |= _PAGE_NO_CACHE;
		if (map->type == _DRM_REGISTERS)
			pgprot_val(vma->vm_page_prot) |= _PAGE_GUARDED;
#endif
		vma->vm_flags |= VM_IO;	/* not in core dump */
#if defined(__ia64__)
		if (efi_range_is_wc(vma->vm_start, vma->vm_end -
				    vma->vm_start))
			vma->vm_page_prot =
				pgprot_writecombine(vma->vm_page_prot);
		else
			vma->vm_page_prot =
				pgprot_noncached(vma->vm_page_prot);
#endif
		offset = dev->driver->get_reg_ofs(dev);
#ifdef __sparc__
		if (io_remap_pfn_range(DRM_RPR_ARG(vma) vma->vm_start,
					(map->offset + offset) >> PAGE_SHIFT,
					vma->vm_end - vma->vm_start,
					vma->vm_page_prot))
#else
		if (io_remap_pfn_range(vma, vma->vm_start,
				     (map->offset + offset) >> PAGE_SHIFT,
				     vma->vm_end - vma->vm_start,
				     vma->vm_page_prot))
#endif
				return -EAGAIN;
		DRM_DEBUG("   Type = %d; start = 0x%lx, end = 0x%lx,"
			  " offset = 0x%lx\n",
			  map->type,
			  vma->vm_start, vma->vm_end, map->offset + offset);
		vma->vm_ops = &drm_vm_ops;
		break;
	case _DRM_SHM:
	case _DRM_CONSISTENT:
		/* Consistent memory is really like shared memory. It's only
		 * allocate in a different way */
		vma->vm_ops = &drm_vm_shm_ops;
		vma->vm_private_data = (void *)map;
				/* Don't let this area swap.  Change when
				   DRM_KERNEL advisory is supported. */
		vma->vm_flags |= VM_RESERVED;
		break;
	case _DRM_SCATTER_GATHER:
		vma->vm_ops = &drm_vm_sg_ops;
		vma->vm_private_data = (void *)map;
		vma->vm_flags |= VM_RESERVED;
                break;
	default:
		return -EINVAL;	/* This should never happen. */
	}
	vma->vm_flags |= VM_RESERVED; /* Don't swap */

	vma->vm_file  =	 filp;	/* Needed for drm_vm_open() */
	drm_vm_open(vma);
	return 0;
}
EXPORT_SYMBOL(drm_mmap);