drm/omapdrm: Use regular fbdev I/O helpers

Use the regular fbdev helpers for framebuffer I/O instead of DRM's
helpers. Omapdrm does not use damage handling, so DRM's fbdev helpers
are mere wrappers around the fbdev code.

By using fbdev helpers directly within each DRM fbdev emulation,
we can eventually remove DRM's wrapper functions entirely.

v4:
	* use initializer macros for struct fb_ops
v2:
	* use FB_SYS_HELPERS option

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Tomi Valkeinen <tomba@kernel.org>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230530151228.22979-9-tzimmermann@suse.de

drivers/gpu/drm/omapdrm/Kconfig

@@ -4,6 +4,7 @@ config DRM_OMAP
 	depends on DRM && OF
 	depends on ARCH_OMAP2PLUS
 	select DRM_KMS_HELPER
+	select FB_SYS_HELPERS if DRM_FBDEV_EMULATION
 	select VIDEOMODE_HELPERS
 	select HDMI
 	default n

drivers/gpu/drm/omapdrm/omap_fbdev.c

@@ -4,6 +4,8 @@
  * Author: Rob Clark <rob@ti.com>
  */
 
+#include <linux/fb.h>
+
 #include <drm/drm_drv.h>
 #include <drm/drm_crtc_helper.h>
 #include <drm/drm_fb_helper.h>
@@ -95,20 +97,13 @@ static void omap_fbdev_fb_destroy(struct fb_info *info)
 
 static const struct fb_ops omap_fb_ops = {
 	.owner = THIS_MODULE,
-
+	FB_DEFAULT_SYS_OPS,
 	.fb_check_var	= drm_fb_helper_check_var,
 	.fb_set_par	= drm_fb_helper_set_par,
 	.fb_setcmap	= drm_fb_helper_setcmap,
 	.fb_blank	= drm_fb_helper_blank,
 	.fb_pan_display = omap_fbdev_pan_display,
 	.fb_ioctl	= drm_fb_helper_ioctl,
-
-	.fb_read = drm_fb_helper_sys_read,
-	.fb_write = drm_fb_helper_sys_write,
-	.fb_fillrect = drm_fb_helper_sys_fillrect,
-	.fb_copyarea = drm_fb_helper_sys_copyarea,
-	.fb_imageblit = drm_fb_helper_sys_imageblit,
-
 	.fb_destroy = omap_fbdev_fb_destroy,
 };