fbdev: Acquire framebuffer apertures for firmware devices

When registering a generic framebuffer, automatically acquire ownership
of the framebuffer's I/O range. The device will now be handled by the
aperture helpers. Fbdev-based conflict handling is no longer required.

v2:
	* use fb_ prefix instead of fbm_ (Javier)
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220718072322.8927-11-tzimmermann@suse.de

drivers/video/fbdev/core/fbmem.c

@@ -13,6 +13,7 @@
 
 #include <linux/module.h>
 
+#include <linux/aperture.h>
 #include <linux/compat.h>
 #include <linux/types.h>
 #include <linux/errno.h>
@@ -1751,6 +1752,32 @@ static void do_unregister_framebuffer(struct fb_info *fb_info)
 	put_fb_info(fb_info);
 }
 
+static int fb_aperture_acquire_for_platform_device(struct fb_info *fb_info)
+{
+	struct apertures_struct *ap = fb_info->apertures;
+	struct device *dev = fb_info->device;
+	struct platform_device *pdev;
+	unsigned int i;
+	int ret;
+
+	if (!ap)
+		return 0;
+
+	if (!dev_is_platform(dev))
+		return 0;
+
+	pdev = to_platform_device(dev);
+
+	for (ret = 0, i = 0; i < ap->count; ++i) {
+		ret = devm_aperture_acquire_for_platform_device(pdev, ap->ranges[i].base,
+								ap->ranges[i].size);
+		if (ret)
+			break;
+	}
+
+	return ret;
+}
+
 /**
  * remove_conflicting_framebuffers - remove firmware-configured framebuffers
  * @a: memory range, users of which are to be removed
@@ -1801,6 +1828,12 @@ register_framebuffer(struct fb_info *fb_info)
 {
 	int ret;
 
+	if (fb_info->flags & FBINFO_MISC_FIRMWARE) {
+		ret = fb_aperture_acquire_for_platform_device(fb_info);
+		if (ret)
+			return ret;
+	}
+
 	mutex_lock(&registration_lock);
 	ret = do_register_framebuffer(fb_info);
 	mutex_unlock(&registration_lock);