drm_fbdev_generic.c

// SPDX-License-Identifier: MIT

#include <linux/moduleparam.h>
#include <linux/vmalloc.h>

#include <drm/drm_crtc_helper.h>
#include <drm/drm_drv.h>
#include <drm/drm_fb_helper.h>
#include <drm/drm_framebuffer.h>
#include <drm/drm_gem.h>
#include <drm/drm_print.h>

#include <drm/drm_fbdev_generic.h>

/* @user: 1=userspace, 0=fbcon */
static int drm_fbdev_generic_fb_open(struct fb_info *info, int user)
{
	struct drm_fb_helper *fb_helper = info->par;

	/* No need to take a ref for fbcon because it unbinds on unregister */
	if (user && !try_module_get(fb_helper->dev->driver->fops->owner))
		return -ENODEV;

	return 0;
}

static int drm_fbdev_generic_fb_release(struct fb_info *info, int user)
{
	struct drm_fb_helper *fb_helper = info->par;

	if (user)
		module_put(fb_helper->dev->driver->fops->owner);

	return 0;
}

FB_GEN_DEFAULT_DEFERRED_SYSMEM_OPS(drm_fbdev_generic,
				   drm_fb_helper_damage_range,
				   drm_fb_helper_damage_area);

static void drm_fbdev_generic_fb_destroy(struct fb_info *info)
{
	struct drm_fb_helper *fb_helper = info->par;
	void *shadow = info->screen_buffer;

	if (!fb_helper->dev)
		return;

	fb_deferred_io_cleanup(info);
	drm_fb_helper_fini(fb_helper);
	vfree(shadow);
	drm_client_framebuffer_delete(fb_helper->buffer);

	drm_client_release(&fb_helper->client);
	drm_fb_helper_unprepare(fb_helper);
	kfree(fb_helper);
}

static const struct fb_ops drm_fbdev_generic_fb_ops = {
	.owner		= THIS_MODULE,
	.fb_open	= drm_fbdev_generic_fb_open,
	.fb_release	= drm_fbdev_generic_fb_release,
	FB_DEFAULT_DEFERRED_OPS(drm_fbdev_generic),
	DRM_FB_HELPER_DEFAULT_OPS,
	.fb_destroy	= drm_fbdev_generic_fb_destroy,
};

/*
 * This function uses the client API to create a framebuffer backed by a dumb buffer.
 */