Linux内核DRM实现分析——基于i915

1  接口
     我们先看看i915_drv.c里面申明的driver变量：
static struct drm_driver driver = {
 /* don't use mtrr's here, the Xserver or user space app should
  * deal with them for intel hardware.
  */
 .driver_features =
     DRIVER_USE_AGP | DRIVER_REQUIRE_AGP | /* DRIVER_USE_MTRR |*/
     DRIVER_HAVE_IRQ | DRIVER_IRQ_SHARED | DRIVER_GEM,
 .load = i915_driver_load,
 .unload = i915_driver_unload,
 .open = i915_driver_open,
 .lastclose = i915_driver_lastclose,
 .preclose = i915_driver_preclose,
 .postclose = i915_driver_postclose,
 .suspend = i915_suspend,
 .resume = i915_resume,
 .device_is_agp = i915_driver_device_is_agp,
 .enable_vblank = i915_enable_vblank,
 .disable_vblank = i915_disable_vblank,
 .irq_preinstall = i915_driver_irq_preinstall,
 .irq_postinstall = i915_driver_irq_postinstall,
 .irq_uninstall = i915_driver_irq_uninstall,
 .irq_handler = i915_driver_irq_handler,
 .reclaim_buffers = drm_core_reclaim_buffers,
 .get_map_ofs = drm_core_get_map_ofs,
 .get_reg_ofs = drm_core_get_reg_ofs,
 .master_create = i915_master_create,
 .master_destroy = i915_master_destroy,
#if defined(CONFIG_DEBUG_FS)
 .debugfs_init = i915_gem_debugfs_init,
 .debugfs_cleanup = i915_gem_debugfs_cleanup,
#endif
 .gem_init_object = i915_gem_init_object,
 .gem_free_object = i915_gem_free_object,
 .gem_vm_ops = &i915_gem_vm_ops,
 .ioctls = i915_ioctls,
 .fops = {
   .owner = THIS_MODULE,
   .open = drm_open,
   .release = drm_release,
   .ioctl = drm_ioctl,
   .mmap = drm_gem_mmap,
   .poll = drm_poll,
   .fasync = drm_fasync,
#ifdef CONFIG_COMPAT
   .compat_ioctl = i915_compat_ioctl,
#endif
 },
 .pci_driver = {
   .name