parisc/stifb: Implement fb_is_primary_device()

Implement fb_is_primary_device() function, so that fbcon detects if this
framebuffer belongs to the default graphics card which was used to start
the system.

Signed-off-by: Helge Deller <[e-mail]>
Cc: [e-mail] # v5.10+

arch/parisc/include/asm/fb.h

···
 	pgprot_val(vma->vm_page_prot) |= _PAGE_NO_CACHE;
 }
 
+#if defined(CONFIG_STI_CONSOLE) || defined(CONFIG_FB_STI)
+int fb_is_primary_device(struct fb_info *info);
+#else
 static inline int fb_is_primary_device(struct fb_info *info)
 {
 	return 0;
 }
+#endif
 
 #endif /* _ASM_FB_H_ */

drivers/video/console/sticore.c

···
 #include <asm/pdc.h>
 #include <asm/cacheflush.h>
 #include <asm/grfioctl.h>
+#include <asm/fb.h>
 
 #include "../fbdev/sticore.h"
 
···
 
 	return ret;
 }
+
+/* check if given fb_info is the primary device */
+int fb_is_primary_device(struct fb_info *info)
+{
+	struct sti_struct *sti;
+
+	sti = sti_get_rom(0);
+
+	/* if no built-in graphics card found, allow any fb driver as default */
+	if (!sti)
+		return true;
+
+	/* return true if it's the default built-in framebuffer driver */
+	return (sti->info == info);
+}
+EXPORT_SYMBOL(fb_is_primary_device);
 
 MODULE_AUTHOR("Philipp Rumpf, Helge Deller, Thomas Bogendoerfer");
 MODULE_DESCRIPTION("Core STI driver for HP's NGLE series graphics cards in HP PARISC machines");

drivers/video/fbdev/stifb.c

···
 		goto out_err3;
 	}
 
+	/* save for primary gfx device detection & unregister_framebuffer() */
+	sti->info = info;
 	if (register_framebuffer(&fb->info) < 0)
 		goto out_err4;
-
-	sti->info = info; /* save for unregister_framebuffer() */
 
 	fb_info(&fb->info, "%s %dx%d-%d frame buffer device, %s, id: %04x, mmio: 0x%04lx\n",
 		fix->id,