drm/simpledrm: Acquire memory aperture for framebuffer

We register the simplekms device with the DRM platform helpers. A
native driver for the graphics hardware will kick-out the simpledrm
driver before taking over the device.

The original generic platform device from the simple-framebuffer boot
code will be unregistered. The native driver will use whatever native
hardware device it received.

v4:
	* convert to drm_aperture_acquire_from_firmware()
v3:
	* use platform_device_unregister() and handle detachment
	  like hot-unplug event (Daniel)
v2:
	* adapt to aperture changes
	* use drm_dev_unplug() and drm_dev_enter/exit()
	* don't split error string
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Maxime Ripard <maxime@cerno.tech>
Tested-by: nerdopolis <bluescreen_avenger@verizon.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20210430105840.30515-10-tzimmermann@suse.de

drivers/gpu/drm/tiny/simpledrm.c

@@ -6,6 +6,7 @@
 #include <linux/platform_device.h>
 #include <linux/regulator/consumer.h>
 
+#include <drm/drm_aperture.h>
 #include <drm/drm_atomic_state_helper.h>
 #include <drm/drm_connector.h>
 #include <drm/drm_damage_helper.h>
@@ -517,14 +518,23 @@ static int simpledrm_device_init_fb(struct simpledrm_device *sdev)
 
 static int simpledrm_device_init_mm(struct simpledrm_device *sdev)
 {
+	struct drm_device *dev = &sdev->dev;
 	struct platform_device *pdev = sdev->pdev;
 	struct resource *mem;
 	void __iomem *screen_base;
+	int ret;
 
 	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	if (!mem)
 		return -EINVAL;
 
+	ret = devm_aperture_acquire_from_firmware(dev, mem->start, resource_size(mem));
+	if (ret) {
+		drm_err(dev, "could not acquire memory range [0x%llx:0x%llx]: error %d\n",
+			mem->start, mem->end, ret);
+		return ret;
+	}
+
 	screen_base = devm_ioremap_wc(&pdev->dev, mem->start,
 				      resource_size(mem));
 	if (!screen_base)
@@ -625,12 +635,18 @@ simpledrm_simple_display_pipe_enable(struct drm_simple_display_pipe *pipe,
 	struct drm_shadow_plane_state *shadow_plane_state = to_drm_shadow_plane_state(plane_state);
 	struct drm_framebuffer *fb = plane_state->fb;
 	void *vmap = shadow_plane_state->map[0].vaddr; /* TODO: Use mapping abstraction properly */
+	struct drm_device *dev = &sdev->dev;
+	int idx;
 
 	if (!fb)
 		return;
 
+	if (!drm_dev_enter(dev, &idx))
+		return;
+
 	drm_fb_blit_dstclip(sdev->screen_base, sdev->pitch,
 			    sdev->format->format, vmap, fb);
+	drm_dev_exit(idx);
 }
 
 static void
@@ -658,7 +674,9 @@ simpledrm_simple_display_pipe_update(struct drm_simple_display_pipe *pipe,
 	struct drm_shadow_plane_state *shadow_plane_state = to_drm_shadow_plane_state(plane_state);
 	void *vmap = shadow_plane_state->map[0].vaddr; /* TODO: Use mapping abstraction properly */
 	struct drm_framebuffer *fb = plane_state->fb;
+	struct drm_device *dev = &sdev->dev;
 	struct drm_rect clip;
+	int idx;
 
 	if (!fb)
 		return;
@@ -666,8 +684,13 @@ simpledrm_simple_display_pipe_update(struct drm_simple_display_pipe *pipe,
 	if (!drm_atomic_helper_damage_merged(old_plane_state, plane_state, &clip))
 		return;
 
+	if (!drm_dev_enter(dev, &idx))
+		return;
+
 	drm_fb_blit_rect_dstclip(sdev->screen_base, sdev->pitch,
 				 sdev->format->format, vmap, fb, &clip);
+
+	drm_dev_exit(idx);
 }
 
 static const struct drm_simple_display_pipe_funcs
@@ -847,7 +870,7 @@ static int simpledrm_remove(struct platform_device *pdev)
 	struct simpledrm_device *sdev = platform_get_drvdata(pdev);
 	struct drm_device *dev = &sdev->dev;
 
-	drm_dev_unregister(dev);
+	drm_dev_unplug(dev);
 
 	return 0;
 }