fbdev/savagefb: 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: Antonino Daplas <adaplas@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230927074722.6197-35-tzimmermann@suse.de

drivers/video/fbdev/Kconfig

@@ -1163,10 +1163,11 @@ config FB_S3_DDC
 config FB_SAVAGE
 	tristate "S3 Savage support"
 	depends on FB && PCI
-	select FB_MODE_HELPERS
 	select FB_CFB_FILLRECT
 	select FB_CFB_COPYAREA
 	select FB_CFB_IMAGEBLIT
+	select FB_IOMEM_FOPS
+	select FB_MODE_HELPERS
 	select VGASTATE
 	select VIDEO_NOMODESET
 	help

drivers/video/fbdev/savage/savagefb_driver.c

@@ -1641,6 +1641,7 @@ static const struct fb_ops savagefb_ops = {
 	.owner          = THIS_MODULE,
 	.fb_open        = savagefb_open,
 	.fb_release     = savagefb_release,
+	__FB_DEFAULT_IOMEM_OPS_RDWR,
 	.fb_check_var   = savagefb_check_var,
 	.fb_set_par     = savagefb_set_par,
 	.fb_setcolreg   = savagefb_setcolreg,
@@ -1652,10 +1653,9 @@ static const struct fb_ops savagefb_ops = {
 	.fb_imageblit   = savagefb_imageblit,
 	.fb_sync        = savagefb_sync,
 #else
-	.fb_fillrect    = cfb_fillrect,
-	.fb_copyarea    = cfb_copyarea,
-	.fb_imageblit   = cfb_imageblit,
+	__FB_DEFAULT_IOMEM_OPS_DRAW,
 #endif
+	__FB_DEFAULT_IOMEM_OPS_MMAP,
 };
 
 /* --------------------------------------------------------------------- */