drm/fb-helper: Perform all fbdev I/O with the same implementation

Implement the fbdev's read/write helpers with the same functions. Use
the generic fbdev's code as template. Convert all drivers.

DRM's fb helpers must implement regular I/O functionality in struct
fb_ops and possibly perform a damage update. Handle all this in the
same functions and convert drivers. The functionality has been used
as part of the generic fbdev code for some time. The drivers don't
set struct drm_fb_helper.fb_dirty, so they will not be affected by
damage handling.

For I/O memory, fb helpers now provide drm_fb_helper_cfb_read() and
drm_fb_helper_cfb_write(). Several drivers require these. Until now
tegra used I/O read and write, although the memory buffer appears to
be in system memory. So use _sys_ helpers now.

v3:
	* fix docs (Javier)
v2:
	* rebase onto vmwgfx changes
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221103151446.2638-18-tzimmermann@suse.de

drivers/gpu/drm/armada/armada_fbdev.c

@@ -19,6 +19,8 @@
 static const struct fb_ops armada_fb_ops = {
 	.owner		= THIS_MODULE,
 	DRM_FB_HELPER_DEFAULT_OPS,
+	.fb_read	= drm_fb_helper_cfb_read,
+	.fb_write	= drm_fb_helper_cfb_write,
 	.fb_fillrect	= drm_fb_helper_cfb_fillrect,
 	.fb_copyarea	= drm_fb_helper_cfb_copyarea,
 	.fb_imageblit	= drm_fb_helper_cfb_imageblit,

drivers/gpu/drm/exynos/exynos_drm_fbdev.c

@@ -49,6 +49,8 @@ static const struct fb_ops exynos_drm_fb_ops = {
 	.owner		= THIS_MODULE,
 	DRM_FB_HELPER_DEFAULT_OPS,
 	.fb_mmap        = exynos_drm_fb_mmap,
+	.fb_read	= drm_fb_helper_cfb_read,
+	.fb_write	= drm_fb_helper_cfb_write,
 	.fb_fillrect	= drm_fb_helper_cfb_fillrect,
 	.fb_copyarea	= drm_fb_helper_cfb_copyarea,
 	.fb_imageblit	= drm_fb_helper_cfb_imageblit,

drivers/gpu/drm/gma500/framebuffer.c

@@ -147,6 +147,8 @@ static const struct fb_ops psbfb_unaccel_ops = {
 	.owner = THIS_MODULE,
 	DRM_FB_HELPER_DEFAULT_OPS,
 	.fb_setcolreg = psbfb_setcolreg,
+	.fb_read = drm_fb_helper_cfb_read,
+	.fb_write = drm_fb_helper_cfb_write,
 	.fb_fillrect = drm_fb_helper_cfb_fillrect,
 	.fb_copyarea = drm_fb_helper_cfb_copyarea,
 	.fb_imageblit = drm_fb_helper_cfb_imageblit,

drivers/gpu/drm/i915/display/intel_fbdev.c

@@ -124,6 +124,8 @@ static const struct fb_ops intelfb_ops = {
 	.owner = THIS_MODULE,
 	DRM_FB_HELPER_DEFAULT_OPS,
 	.fb_set_par = intel_fbdev_set_par,
+	.fb_read = drm_fb_helper_cfb_read,
+	.fb_write = drm_fb_helper_cfb_write,
 	.fb_fillrect = drm_fb_helper_cfb_fillrect,
 	.fb_copyarea = drm_fb_helper_cfb_copyarea,
 	.fb_imageblit = drm_fb_helper_cfb_imageblit,

drivers/gpu/drm/radeon/radeon_fb.c

@@ -80,6 +80,8 @@ static const struct fb_ops radeonfb_ops = {
 	DRM_FB_HELPER_DEFAULT_OPS,
 	.fb_open = radeonfb_open,
 	.fb_release = radeonfb_release,
+	.fb_read = drm_fb_helper_cfb_read,
+	.fb_write = drm_fb_helper_cfb_write,
 	.fb_fillrect = drm_fb_helper_cfb_fillrect,
 	.fb_copyarea = drm_fb_helper_cfb_copyarea,
 	.fb_imageblit = drm_fb_helper_cfb_imageblit,

drivers/gpu/drm/tegra/fb.c

@@ -206,6 +206,8 @@ static int tegra_fb_mmap(struct fb_info *info, struct vm_area_struct *vma)
 static const struct fb_ops tegra_fb_ops = {
 	.owner = THIS_MODULE,
 	DRM_FB_HELPER_DEFAULT_OPS,
+	.fb_read = drm_fb_helper_sys_read,
+	.fb_write = drm_fb_helper_sys_write,
 	.fb_fillrect = drm_fb_helper_sys_fillrect,
 	.fb_copyarea = drm_fb_helper_sys_copyarea,
 	.fb_imageblit = drm_fb_helper_sys_imageblit,

include/drm/drm_fb_helper.h

@@ -257,6 +257,11 @@ void drm_fb_helper_sys_copyarea(struct fb_info *info,
 void drm_fb_helper_sys_imageblit(struct fb_info *info,
 				 const struct fb_image *image);
 
+ssize_t drm_fb_helper_cfb_read(struct fb_info *info, char __user *buf,
+			       size_t count, loff_t *ppos);
+ssize_t drm_fb_helper_cfb_write(struct fb_info *info, const char __user *buf,
+				size_t count, loff_t *ppos);
+
 void drm_fb_helper_cfb_fillrect(struct fb_info *info,
 				const struct fb_fillrect *rect);
 void drm_fb_helper_cfb_copyarea(struct fb_info *info,
@@ -402,6 +407,18 @@ static inline void drm_fb_helper_sys_imageblit(struct fb_info *info,
 {
 }
 
+static inline ssize_t drm_fb_helper_cfb_read(struct fb_info *info, char __user *buf,
+					     size_t count, loff_t *ppos)
+{
+	return -ENODEV;
+}
+
+static inline ssize_t drm_fb_helper_cfb_write(struct fb_info *info, const char __user *buf,
+					      size_t count, loff_t *ppos)
+{
+	return -ENODEV;
+}
+
 static inline void drm_fb_helper_cfb_fillrect(struct fb_info *info,
 					      const struct fb_fillrect *rect)
 {