drm/simpledrm: Use struct iosys_map consistently

The majority of the driver already uses struct iosys_map to encapsulate
accesses to I/O remapped vs. system memory. Accesses via the screen base
pointer still use __iomem annotations, which can lead to inconsistencies
and conflicts with subsequent patches.

Convert the screen base to a struct iosys_map as well for consistency
and to avoid these issues.
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230120173103.4002342-5-thierry.reding@gmail.com

drivers/gpu/drm/tiny/simpledrm.c

@@ -208,7 +208,7 @@ struct simpledrm_device {
 	unsigned int pitch;
 
 	/* memory management */
-	void __iomem *screen_base;
+	struct iosys_map screen_base;
 
 	/* modesetting */
 	uint32_t formats[8];
@@ -473,15 +473,15 @@ static void simpledrm_primary_plane_helper_atomic_update(struct drm_plane *plane
 
 	drm_atomic_helper_damage_iter_init(&iter, old_plane_state, plane_state);
 	drm_atomic_for_each_plane_damage(&iter, &damage) {
-		struct iosys_map dst = IOSYS_MAP_INIT_VADDR(sdev->screen_base);
 		struct drm_rect dst_clip = plane_state->dst;
+		struct iosys_map dst = sdev->screen_base;
 
 		if (!drm_rect_intersect(&dst_clip, &damage))
 			continue;
 
 		iosys_map_incr(&dst, drm_fb_clip_offset(sdev->pitch, sdev->format, &dst_clip));
-		drm_fb_blit(&dst, &sdev->pitch, sdev->format->format, shadow_plane_state->data, fb,
-			    &damage);
+		drm_fb_blit(&dst, &sdev->pitch, sdev->format->format, shadow_plane_state->data,
+			    fb, &damage);
 	}
 
 	drm_dev_exit(idx);
@@ -500,7 +500,7 @@ static void simpledrm_primary_plane_helper_atomic_disable(struct drm_plane *plan
 		return;
 
 	/* Clear screen to black if disabled */
-	memset_io(sdev->screen_base, 0, sdev->pitch * sdev->mode.vdisplay);
+	iosys_map_memset(&sdev->screen_base, 0, 0, sdev->pitch * sdev->mode.vdisplay);
 
 	drm_dev_exit(idx);
 }
@@ -703,7 +703,8 @@ static struct simpledrm_device *simpledrm_device_create(struct drm_driver *drv,
 	screen_base = devm_ioremap_wc(&pdev->dev, mem->start, resource_size(mem));
 	if (!screen_base)
 		return ERR_PTR(-ENOMEM);
-	sdev->screen_base = screen_base;
+
+	iosys_map_set_vaddr_iomem(&sdev->screen_base, screen_base);
 
 	/*
 	 * Modesetting