fbdev/tgafb: 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/20230927074722.6197-42-tzimmermann@suse.de

drivers/video/fbdev/Kconfig

@@ -416,10 +416,11 @@ config FB_TGA
 	depends on FB
 	depends on PCI || TC
 	depends on ALPHA || TC
+	select BITREVERSE
 	select FB_CFB_FILLRECT
 	select FB_CFB_COPYAREA
 	select FB_CFB_IMAGEBLIT
-	select BITREVERSE
+	select FB_IOMEM_FOPS
 	select VIDEO_NOMODESET
 	help
 	  This is the frame buffer device driver for generic TGA and SFB+

drivers/video/fbdev/tgafb.c

@@ -73,6 +73,7 @@ static struct tc_driver tgafb_tc_driver;
 
 static const struct fb_ops tgafb_ops = {
 	.owner			= THIS_MODULE,
+	__FB_DEFAULT_IOMEM_OPS_RDWR,
 	.fb_check_var		= tgafb_check_var,
 	.fb_set_par		= tgafb_set_par,
 	.fb_setcolreg		= tgafb_setcolreg,
@@ -81,6 +82,7 @@ static const struct fb_ops tgafb_ops = {
 	.fb_fillrect		= tgafb_fillrect,
 	.fb_copyarea		= tgafb_copyarea,
 	.fb_imageblit		= tgafb_imageblit,
+	__FB_DEFAULT_IOMEM_OPS_MMAP,
 };