firmware: sysfb: Add a sysfb_handles_screen_info() helper function

That can be used by drivers to check if the Generic System Framebuffers
(sysfb) support can handle the data contained in the global screen_info.

Drivers might need this information to know if have to setup the system
framebuffer, or if they have to delegate this action to sysfb instead.

Suggested-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://lore.kernel.org/r/20240916110040.1688511-2-javierm@redhat.com
Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>

Author: martinezjavier

drivers/firmware/sysfb.c

@@ -77,6 +77,25 @@ void sysfb_disable(struct device *dev)
 }
 EXPORT_SYMBOL_GPL(sysfb_disable);
 
+/**
+ * sysfb_handles_screen_info() - reports if sysfb handles the global screen_info
+ *
+ * Callers can use sysfb_handles_screen_info() to determine whether the Generic
+ * System Framebuffers (sysfb) can handle the global screen_info data structure
+ * or not. Drivers might need this information to know if they have to setup the
+ * system framebuffer, or if they have to delegate this action to sysfb instead.
+ *
+ * Returns:
+ * True if sysfb handles the global screen_info data structure.
+ */
+bool sysfb_handles_screen_info(void)
+{
+	const struct screen_info *si = &screen_info;
+
+	return !!screen_info_video_type(si);
+}
+EXPORT_SYMBOL_GPL(sysfb_handles_screen_info);
+
 #if defined(CONFIG_PCI)
 static bool sysfb_pci_dev_is_enabled(struct pci_dev *pdev)
 {

include/linux/sysfb.h

@@ -60,12 +60,19 @@ struct efifb_dmi_info {
 
 void sysfb_disable(struct device *dev);
 
+bool sysfb_handles_screen_info(void);
+
 #else /* CONFIG_SYSFB */
 
 static inline void sysfb_disable(struct device *dev)
 {
 }
 
+static inline bool sysfb_handles_screen_info(void)
+{
+	return false;
+}
+
 #endif /* CONFIG_SYSFB */
 
 #ifdef CONFIG_EFI