fbdev/pm3fb: 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/20230927074722.6197-28-tzimmermann@suse.de

drivers/video/fbdev/Kconfig

@@ -1404,6 +1404,7 @@ config FB_PM3
 	select FB_CFB_FILLRECT
 	select FB_CFB_COPYAREA
 	select FB_CFB_IMAGEBLIT
+	select FB_IOMEM_FOPS
 	select VIDEO_NOMODESET
 	help
 	  This is the frame buffer device driver for the 3DLabs Permedia3

drivers/video/fbdev/pm3fb.c

@@ -1203,6 +1203,7 @@ static int pm3fb_blank(int blank_mode, struct fb_info *info)
 
 static const struct fb_ops pm3fb_ops = {
 	.owner		= THIS_MODULE,
+	__FB_DEFAULT_IOMEM_OPS_RDWR,
 	.fb_check_var	= pm3fb_check_var,
 	.fb_set_par	= pm3fb_set_par,
 	.fb_setcolreg	= pm3fb_setcolreg,
@@ -1213,6 +1214,7 @@ static const struct fb_ops pm3fb_ops = {
 	.fb_blank	= pm3fb_blank,
 	.fb_sync	= pm3fb_sync,
 	.fb_cursor	= pm3fb_cursor,
+	__FB_DEFAULT_IOMEM_OPS_MMAP,
 };
 
 /* ------------------------------------------------------------------------- */