[PATCH 6/8] fbdev: Export default read and write operations as fb_cfb_{read, write}()

[Thomas Zimmermann]

Read and write operations on the fbdev framebuffer can now be called by
in-kernel users. This is required by DRM's fbdev helpers.

Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
---
 drivers/video/fbdev/core/fbmem.c | 53 ++++++++++++++++++++++++--------
 include/linux/fb.h               |  5 +++
 2 files changed, 46 insertions(+), 12 deletions(-)

diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c
index 95c32952fa8a..e49cf2988001 100644
--- a/drivers/video/fbdev/core/fbmem.c
+++ b/drivers/video/fbdev/core/fbmem.c
@@ -754,11 +754,10 @@ static struct fb_info *file_fb_info(struct file *file)
 	return info;
 }
 
-static ssize_t
-fb_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
+ssize_t
+fb_cfb_read(struct fb_info *info, char __user *buf, size_t count, loff_t *ppos)
 {
 	unsigned long p = *ppos;
-	struct fb_info *info = file_fb_info(file);
 	u8 *buffer, *dst;
 	u8 __iomem *src;
 	int c, cnt = 0, err = 0;
@@ -770,9 +769,6 @@ fb_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
 	if (info->state != FBINFO_STATE_RUNNING)
 		return -EPERM;
 
-	if (info->fbops->fb_read)
-		return info->fbops->fb_read(info, buf, count, ppos);
-	
 	total_size = info->screen_size;
 
 	if (total_size == 0)
@@ -818,12 +814,13 @@ fb_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
 
 	return (err) ? err : cnt;
 }
+EXPORT_SYMBOL(fb_cfb_read);
 
-static ssize_t
-fb_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
+ssize_t
+fb_cfb_write(struct fb_info *info, const char __user *buf, size_t count,
+	     loff_t *ppos)
 {
 	unsigned long p = *ppos;
-	struct fb_info *info = file_fb_info(file);
 	u8 *buffer, *src;
 	u8 __iomem *dst;
 	int c, cnt = 0, err = 0;
@@ -835,9 +832,6 @@ fb_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
 	if (info->state != FBINFO_STATE_RUNNING)
 		return -EPERM;
 
-	if (info->fbops->fb_write)
-		return info->fbops->fb_write(info, buf, count, ppos);
-	
 	total_size = info->screen_size;
 
 	if (total_size == 0)
@@ -890,6 +884,41 @@ fb_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
 
 	return (cnt) ? cnt : err;
 }
+EXPORT_SYMBOL(fb_cfb_write);
+
+static ssize_t
+fb_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
+{
+	struct fb_info *info = file_fb_info(file);
+
+	if (!info || !info->screen_base)
+		return -ENODEV;
+
+	if (info->state != FBINFO_STATE_RUNNING)
+		return -EPERM;
+
+	if (info->fbops->fb_read)
+		return info->fbops->fb_read(info, buf, count, ppos);
+
+	return fb_cfb_read(info, buf, count, ppos);
+}
+
+static ssize_t
+fb_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
+{
+	struct fb_info *info = file_fb_info(file);
+
+	if (!info || !info->screen_base)
+		return -ENODEV;
+
+	if (info->state != FBINFO_STATE_RUNNING)
+		return -EPERM;
+
+	if (info->fbops->fb_write)
+		return info->fbops->fb_write(info, buf, count, ppos);
+
+	return fb_cfb_write(info, buf, count, ppos);
+}
 
 int
 fb_pan_display(struct fb_info *info, struct fb_var_screeninfo *var)
diff --git a/include/linux/fb.h b/include/linux/fb.h
index 41e0069eca0a..c69e098e6dc5 100644
--- a/include/linux/fb.h
+++ b/include/linux/fb.h
@@ -592,6 +592,11 @@ extern int fb_blank(struct fb_info *info, int blank);
 extern void cfb_fillrect(struct fb_info *info, const struct fb_fillrect *rect); 
 extern void cfb_copyarea(struct fb_info *info, const struct fb_copyarea *area); 
 extern void cfb_imageblit(struct fb_info *info, const struct fb_image *image);
+extern ssize_t fb_cfb_read(struct fb_info *info, char __user *buf,
+			   size_t count, loff_t *ppos);
+extern ssize_t fb_cfb_write(struct fb_info *info, const char __user *buf,
+			    size_t count, loff_t *ppos);
+
 /*
  * Drawing operations where framebuffer is in system RAM
  */
-- 
2.23.0