[PATCH 01/25] drm/fb_helper: Add drm_fb_helper functions to manage fb_info creation

[Archit Taneja]

Every drm driver calls framebuffer_alloc, fb_alloc_cmap,
unregister_framebuffer, fb_dealloc_cmap and framebuffer_release in
order to emulate fbdev support.

Create drm_fb_helper functions that perform the above operations.

This is part of an effort to prevent drm drivers from calling fbdev
functions directly. It also removes repetitive code from drivers.

There are some drivers that call alloc_apertures after framebuffer_alloc
and some that don't. Make the helper always call alloc_apertures. This
would make certain drivers allocate memory for apertures but not use
them. Since it's a small amount of memory, it shouldn't be an issue.

Signed-off-by: Archit Taneja <architt at codeaurora.org>
---
 drivers/gpu/drm/drm_fb_helper.c | 53 +++++++++++++++++++++++++++++++++++++++++
 include/drm/drm_fb_helper.h     |  4 ++++
 2 files changed, 57 insertions(+)

diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index cac4229..78859ad 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -667,6 +667,59 @@ out_free:
 }
 EXPORT_SYMBOL(drm_fb_helper_init);
 
+struct fb_info *drm_fb_helper_alloc_fbi(struct drm_fb_helper *fb_helper)
+{
+	struct device *dev = fb_helper->dev->dev;
+	struct fb_info *info;
+	int ret;
+
+	info = framebuffer_alloc(0, dev);
+	if (!info)
+		return ERR_PTR(-ENOMEM);
+
+	ret = fb_alloc_cmap(&info->cmap, 256, 0);
+	if (ret)
+		goto err_release;
+
+	info->apertures = alloc_apertures(1);
+	if (!info->apertures) {
+		ret = -ENOMEM;
+		goto err_free_cmap;
+	}
+
+	fb_helper->fbdev = info;
+
+	return info;
+
+err_free_cmap:
+	fb_dealloc_cmap(&info->cmap);
+err_release:
+	framebuffer_release(info);
+	return ERR_PTR(ret);
+}
+EXPORT_SYMBOL(drm_fb_helper_alloc_fbi);
+
+void drm_fb_helper_unregister_fbi(struct drm_fb_helper *fb_helper)
+{
+	if (fb_helper->fbdev)
+		unregister_framebuffer(fb_helper->fbdev);
+}
+EXPORT_SYMBOL(drm_fb_helper_unregister_fbi);
+
+void drm_fb_helper_release_fbi(struct drm_fb_helper *fb_helper)
+{
+	struct fb_info *info = fb_helper->fbdev;
+
+	if (info) {
+		if (info->cmap.len)
+			fb_dealloc_cmap(&info->cmap);
+		framebuffer_release(info);
+	}
+
+	fb_helper->fbdev = NULL;
+}
+EXPORT_SYMBOL(drm_fb_helper_release_fbi);
+
 void drm_fb_helper_fini(struct drm_fb_helper *fb_helper)
 {
 	if (!list_empty(&fb_helper->kernel_fb_list)) {
diff --git a/include/drm/drm_fb_helper.h b/include/drm/drm_fb_helper.h
index 0dfd94def..2ee4ec5 100644
--- a/include/drm/drm_fb_helper.h
+++ b/include/drm/drm_fb_helper.h
@@ -136,6 +136,10 @@ int drm_fb_helper_check_var(struct fb_var_screeninfo *var,
 			    struct fb_info *info);
 
 bool drm_fb_helper_restore_fbdev_mode_unlocked(struct drm_fb_helper *fb_helper);
+
+struct fb_info *drm_fb_helper_alloc_fbi(struct drm_fb_helper *fb_helper);
+void drm_fb_helper_unregister_fbi(struct drm_fb_helper *fb_helper);
+void drm_fb_helper_release_fbi(struct drm_fb_helper *fb_helper);
 void drm_fb_helper_fill_var(struct fb_info *info, struct drm_fb_helper *fb_helper,
 			    uint32_t fb_width, uint32_t fb_height);
 void drm_fb_helper_fill_fix(struct fb_info *info, uint32_t pitch,
-- 
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