fbdev/radeon: Initialize fb_ops to fbdev I/O-memory helpers

Initialize the instance of struct fb_ops with fbdev initializer
macros for framebuffers in I/O address space. Set the read/write,
draw and mmap callbacks to the correct implementation and avoid
implicit defaults. Also select the necessary I/O helpers in Kconfig.

Fbdev drivers sometimes rely on the callbacks being NULL for a
default implementation to be invoked; hence requiring the I/O
helpers to be built in any case. Setting all callbacks in all
drivers explicitly will allow to make the I/O helpers optional.
This benefits systems that do not use these functions.

No functional changes.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Javier Martinez Canillas <javierm@redhat.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230927074722.6197-30-tzimmermann@suse.de

drivers/video/fbdev/Kconfig

@@ -1025,11 +1025,12 @@ config FB_RADEON
 	tristate "ATI Radeon display support"
 	depends on FB && PCI
 	select FB_BACKLIGHT if FB_RADEON_BACKLIGHT
-	select FB_MODE_HELPERS
 	select FB_CFB_FILLRECT
 	select FB_CFB_COPYAREA
 	select FB_CFB_IMAGEBLIT
+	select FB_IOMEM_FOPS
 	select FB_MACMODES if PPC
+	select FB_MODE_HELPERS
 	select VIDEO_NOMODESET
 	help
 	  Choose this option if you want to use an ATI Radeon graphics card as

drivers/video/fbdev/aty/radeon_base.c

@@ -1952,6 +1952,7 @@ static int radeonfb_set_par(struct fb_info *info)
 
 static const struct fb_ops radeonfb_ops = {
 	.owner			= THIS_MODULE,
+	__FB_DEFAULT_IOMEM_OPS_RDWR,
 	.fb_check_var		= radeonfb_check_var,
 	.fb_set_par		= radeonfb_set_par,
 	.fb_setcolreg		= radeonfb_setcolreg,
@@ -1963,6 +1964,7 @@ static const struct fb_ops radeonfb_ops = {
 	.fb_fillrect		= radeonfb_fillrect,
 	.fb_copyarea		= radeonfb_copyarea,
 	.fb_imageblit		= radeonfb_imageblit,
+	__FB_DEFAULT_IOMEM_OPS_MMAP,
 };