drm/gma500: Implement client-based fbdev emulation

Implement fbdevemulation on top of struct drm_client and its helpers.
This ad-hoc interfaces for restoring and closing fbdev emulation with
per-client callback for hotplugging, restoring and unregistering.

A single function, psb_fbdev_setup(), starts fbdev emulation after
the DRM device has been registered. Hence, fbdev acts like a regular
DRM client.

The setup call only prepares the fbdev emulation. It then implements
connector hotplugging. The first successful hotplug event initializes
fbdev emulation.

Unregistering depends on the hotplugging. Fully initialized emulation
is cleaned up through drm_fb_helper_unregister_info() and fb_destroy.
For prepared-only setups, unregistering unprepares the emulation and
releases all resources. In both cases, fbdev emulation will be cleaned
up.

v2:
	* declare empty setup function as 'static inline' (kernel
	  test robot)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Patrik Jakobsson <patrik.r.jakobsson@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230313151610.14367-7-tzimmermann@suse.de

1 files changed, 102 insertions, 51 deletions

diff --git a/drivers/gpu/drm/gma500/fbdev.c b/drivers/gpu/drm/gma500/fbdev.c
index 74e843f8e64d..0433392c7fbf 100644
--- a/drivers/gpu/drm/gma500/fbdev.c
+++ b/drivers/gpu/drm/gma500/fbdev.c
@@ -8,6 +8,7 @@
 #include <linux/pfn_t.h>
 
 #include <drm/drm_crtc_helper.h>
+#include <drm/drm_drv.h>
 #include <drm/drm_fb_helper.h>
 #include <drm/drm_framebuffer.h>
 
@@ -121,6 +122,27 @@ static int psb_fbdev_fb_mmap(struct fb_info *info, struct vm_area_struct *vma)
 	return 0;
 }
 
+static void psb_fbdev_fb_destroy(struct fb_info *info)
+{
+	struct drm_fb_helper *fb_helper = info->par;
+	struct drm_framebuffer *fb = fb_helper->fb;
+	struct drm_gem_object *obj = fb->obj[0];
+
+	drm_fb_helper_fini(fb_helper);
+
+	drm_framebuffer_unregister_private(fb);
+	fb->obj[0] = NULL;
+	drm_framebuffer_cleanup(fb);
+	kfree(fb);
+
+	drm_gem_object_put(obj);
+
+	drm_client_release(&fb_helper->client);
+
+	drm_fb_helper_unprepare(fb_helper);
+	kfree(fb_helper);
+}
+
 static const struct fb_ops psb_fbdev_fb_ops = {
 	.owner = THIS_MODULE,
 	DRM_FB_HELPER_DEFAULT_OPS,
@@ -131,6 +153,7 @@ static const struct fb_ops psb_fbdev_fb_ops = {
 	.fb_copyarea = drm_fb_helper_cfb_copyarea,
 	.fb_imageblit = drm_fb_helper_cfb_imageblit,
 	.fb_mmap = psb_fbdev_fb_mmap,
+	.fb_destroy = psb_fbdev_fb_destroy,
 };
 
 /*
@@ -190,14 +213,6 @@ static int psb_fbdev_fb_probe(struct drm_fb_helper *fb_helper,
 		return PTR_ERR(backing);
 	obj = &backing->base;
 
-	memset(dev_priv->vram_addr + backing->offset, 0, size);
-
-	info = drm_fb_helper_alloc_info(fb_helper);
-	if (IS_ERR(info)) {
-		ret = PTR_ERR(info);
-		goto err_drm_gem_object_put;
-	}
-
 	fb = psb_framebuffer_create(dev, &mode_cmd, obj);
 	if (IS_ERR(fb)) {
 		ret = PTR_ERR(fb);
@@ -206,28 +221,40 @@ static int psb_fbdev_fb_probe(struct drm_fb_helper *fb_helper,
 
 	fb_helper->fb = fb;
 
-	info->fbops = &psb_fbdev_fb_ops;
-
-	info->fix.smem_start = dev_priv->fb_base;
-	info->fix.smem_len = size;
-	info->fix.ywrapstep = 0;
-	info->fix.ypanstep = 0;
+	info = drm_fb_helper_alloc_info(fb_helper);
+	if (IS_ERR(info)) {
+		ret = PTR_ERR(info);
+		goto err_drm_framebuffer_unregister_private;
+	}
 
+	info->fbops = &psb_fbdev_fb_ops;
+	info->flags = FBINFO_DEFAULT;
 	/* Accessed stolen memory directly */
 	info->screen_base = dev_priv->vram_addr + backing->offset;
 	info->screen_size = size;
 
 	drm_fb_helper_fill_info(info, fb_helper, sizes);
 
+	info->fix.smem_start = dev_priv->fb_base;
+	info->fix.smem_len = size;
+	info->fix.ywrapstep = 0;
+	info->fix.ypanstep = 0;
 	info->fix.mmio_start = pci_resource_start(pdev, 0);
 	info->fix.mmio_len = pci_resource_len(pdev, 0);
 
+	memset(info->screen_base, 0, info->screen_size);
+
 	/* Use default scratch pixmap (info->pixmap.flags = FB_PIXMAP_SYSTEM) */
 
 	dev_dbg(dev->dev, "allocated %dx%d fb\n", fb->width, fb->height);
 
 	return 0;
 
+err_drm_framebuffer_unregister_private:
+	drm_framebuffer_unregister_private(fb);
+	fb->obj[0] = NULL;
+	drm_framebuffer_cleanup(fb);
+	kfree(fb);
 err_drm_gem_object_put:
 	drm_gem_object_put(obj);
 	return ret;
@@ -237,68 +264,92 @@ static const struct drm_fb_helper_funcs psb_fbdev_fb_helper_funcs = {
 	.fb_probe = psb_fbdev_fb_probe,
 };
 
-static int psb_fbdev_destroy(struct drm_device *dev,
-			     struct drm_fb_helper *fb_helper)
-{
-	struct drm_framebuffer *fb = fb_helper->fb;
-
-	drm_fb_helper_unregister_info(fb_helper);
+/*
+ * struct drm_client_funcs and setup code
+ */
 
-	drm_fb_helper_fini(fb_helper);
-	drm_framebuffer_unregister_private(fb);
-	drm_framebuffer_cleanup(fb);
+static void psb_fbdev_client_unregister(struct drm_client_dev *client)
+{
+	struct drm_fb_helper *fb_helper = drm_fb_helper_from_client(client);
+
+	if (fb_helper->info) {
+		drm_fb_helper_unregister_info(fb_helper);
+	} else {
+		drm_fb_helper_unprepare(fb_helper);
+		drm_client_release(&fb_helper->client);
+		kfree(fb_helper);
+	}
+}
 
-	if (fb->obj[0])
-		drm_gem_object_put(fb->obj[0]);
-	kfree(fb);
+static int psb_fbdev_client_restore(struct drm_client_dev *client)
+{
+	drm_fb_helper_lastclose(client->dev);
 
 	return 0;
 }
 
-int psb_fbdev_init(struct drm_device *dev)
+static int psb_fbdev_client_hotplug(struct drm_client_dev *client)
 {
-	struct drm_fb_helper *fb_helper;
-	struct drm_psb_private *dev_priv = to_drm_psb_private(dev);
+	struct drm_fb_helper *fb_helper = drm_fb_helper_from_client(client);
+	struct drm_device *dev = client->dev;
 	int ret;
 
-	fb_helper = kzalloc(sizeof(*fb_helper), GFP_KERNEL);
-	if (!fb_helper)
-		return -ENOMEM;
-
-	dev_priv->fb_helper = fb_helper;
-
-	drm_fb_helper_prepare(dev, fb_helper, 32, &psb_fbdev_fb_helper_funcs);
+	if (dev->fb_helper)
+		return drm_fb_helper_hotplug_event(dev->fb_helper);
 
 	ret = drm_fb_helper_init(dev, fb_helper);
 	if (ret)
-		goto free;
+		goto err_drm_err;
 
-	/* disable all the possible outputs/crtcs before entering KMS mode */
-	drm_helper_disable_unused_functions(dev);
+	if (!drm_drv_uses_atomic_modeset(dev))
+		drm_helper_disable_unused_functions(dev);
 
 	ret = drm_fb_helper_initial_config(fb_helper);
 	if (ret)
-		goto fini;
+		goto err_drm_fb_helper_fini;
 
 	return 0;
 
-fini:
+err_drm_fb_helper_fini:
 	drm_fb_helper_fini(fb_helper);
-free:
-	drm_fb_helper_unprepare(fb_helper);
-	kfree(fb_helper);
+err_drm_err:
+	drm_err(dev, "Failed to setup gma500 fbdev emulation (ret=%d)\n", ret);
 	return ret;
 }
 
-void psb_fbdev_fini(struct drm_device *dev)
+static const struct drm_client_funcs psb_fbdev_client_funcs = {
+	.owner		= THIS_MODULE,
+	.unregister	= psb_fbdev_client_unregister,
+	.restore	= psb_fbdev_client_restore,
+	.hotplug	= psb_fbdev_client_hotplug,
+};
+
+void psb_fbdev_setup(struct drm_psb_private *dev_priv)
 {
-	struct drm_psb_private *dev_priv = to_drm_psb_private(dev);
+	struct drm_device *dev = &dev_priv->dev;
+	struct drm_fb_helper *fb_helper;
+	int ret;
 
-	if (!dev_priv->fb_helper)
+	fb_helper = kzalloc(sizeof(*fb_helper), GFP_KERNEL);
+	if (!fb_helper)
 		return;
+	drm_fb_helper_prepare(dev, fb_helper, 32, &psb_fbdev_fb_helper_funcs);
+
+	ret = drm_client_init(dev, &fb_helper->client, "fbdev-gma500", &psb_fbdev_client_funcs);
+	if (ret) {
+		drm_err(dev, "Failed to register client: %d\n", ret);
+		goto err_drm_fb_helper_unprepare;
+	}
+
+	ret = psb_fbdev_client_hotplug(&fb_helper->client);
+	if (ret)
+		drm_dbg_kms(dev, "client hotplug ret=%d\n", ret);
+
+	drm_client_register(&fb_helper->client);
+
+	return;
 
-	psb_fbdev_destroy(dev, dev_priv->fb_helper);
-	drm_fb_helper_unprepare(dev_priv->fb_helper);
-	kfree(dev_priv->fb_helper);
-	dev_priv->fb_helper = NULL;
+err_drm_fb_helper_unprepare:
+	drm_fb_helper_unprepare(fb_helper);
+	kfree(fb_helper);
 }