fbdev/s3fb: 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>
Link: https://patchwork.freedesktop.org/patch/msgid/20230927074722.6197-33-tzimmermann@suse.de

drivers/video/fbdev/Kconfig

@@ -1145,6 +1145,7 @@ config FB_S3
 	select FB_CFB_FILLRECT
 	select FB_CFB_COPYAREA
 	select FB_CFB_IMAGEBLIT
+	select FB_IOMEM_FOPS
 	select FB_TILEBLITTING
 	select FB_SVGALIB
 	select VGASTATE

drivers/video/fbdev/s3fb.c

@@ -1047,6 +1047,7 @@ static const struct fb_ops s3fb_ops = {
 	.owner		= THIS_MODULE,
 	.fb_open	= s3fb_open,
 	.fb_release	= s3fb_release,
+	__FB_DEFAULT_IOMEM_OPS_RDWR,
 	.fb_check_var	= s3fb_check_var,
 	.fb_set_par	= s3fb_set_par,
 	.fb_setcolreg	= s3fb_setcolreg,
@@ -1055,6 +1056,7 @@ static const struct fb_ops s3fb_ops = {
 	.fb_fillrect	= s3fb_fillrect,
 	.fb_copyarea	= cfb_copyarea,
 	.fb_imageblit	= s3fb_imageblit,
+	__FB_DEFAULT_IOMEM_OPS_MMAP,
 	.fb_get_caps    = svga_get_caps,
 };