fbdev: Add initializer macros for struct fb_ops

For framebuffers in I/O and system memory, add macros that set
struct fb_ops to the respective callback functions.

For deferred I/O, add macros that generate callback functions with
damage handling. Add initializer macros that set struct fb_ops to
the generated callbacks.

These macros can remove a lot boilerplate code from fbdev drivers.
The drivers are supposed to use the macro that is required for its
framebuffer. Each macro is split into smaller helpers, so that
drivers with non-standard callbacks can pick and customize callbacks
as needed. There are individual helper macros for read/write, mmap
and drawing.

v5:
	* fix whitespace errors (Jingfeng)
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230530151228.22979-3-tzimmermann@suse.de

include/linux/fb.h

@@ -538,9 +538,31 @@ extern ssize_t fb_io_read(struct fb_info *info, char __user *buf,
 extern ssize_t fb_io_write(struct fb_info *info, const char __user *buf,
 			   size_t count, loff_t *ppos);
 
+/*
+ * Initializes struct fb_ops for framebuffers in I/O memory.
+ */
+
+#define __FB_DEFAULT_IO_OPS_RDWR \
+	.fb_read	= fb_io_read, \
+	.fb_write	= fb_io_write
+
+#define __FB_DEFAULT_IO_OPS_DRAW \
+	.fb_fillrect	= cfb_fillrect, \
+	.fb_copyarea	= cfb_copyarea, \
+	.fb_imageblit	= cfb_imageblit
+
+#define __FB_DEFAULT_IO_OPS_MMAP \
+	.fb_mmap	= NULL // default implementation
+
+#define FB_DEFAULT_IO_OPS \
+	__FB_DEFAULT_IO_OPS_RDWR, \
+	__FB_DEFAULT_IO_OPS_DRAW, \
+	__FB_DEFAULT_IO_OPS_MMAP
+
 /*
  * Drawing operations where framebuffer is in system RAM
  */
+
 extern void sys_fillrect(struct fb_info *info, const struct fb_fillrect *rect);
 extern void sys_copyarea(struct fb_info *info, const struct fb_copyarea *area);
 extern void sys_imageblit(struct fb_info *info, const struct fb_image *image);
@@ -549,6 +571,27 @@ extern ssize_t fb_sys_read(struct fb_info *info, char __user *buf,
 extern ssize_t fb_sys_write(struct fb_info *info, const char __user *buf,
 			    size_t count, loff_t *ppos);
 
+/*
+ * Initializes struct fb_ops for framebuffers in system memory.
+ */
+
+#define __FB_DEFAULT_SYS_OPS_RDWR \
+	.fb_read	= fb_sys_read, \
+	.fb_write	= fb_sys_write
+
+#define __FB_DEFAULT_SYS_OPS_DRAW \
+	.fb_fillrect	= sys_fillrect, \
+	.fb_copyarea	= sys_copyarea, \
+	.fb_imageblit	= sys_imageblit
+
+#define __FB_DEFAULT_SYS_OPS_MMAP \
+	.fb_mmap	= NULL // default implementation
+
+#define FB_DEFAULT_SYS_OPS \
+	__FB_DEFAULT_SYS_OPS_RDWR, \
+	__FB_DEFAULT_SYS_OPS_DRAW, \
+	__FB_DEFAULT_SYS_OPS_MMAP
+
 /* drivers/video/fbmem.c */
 extern int register_framebuffer(struct fb_info *fb_info);
 extern void unregister_framebuffer(struct fb_info *fb_info);
@@ -604,6 +647,75 @@ extern void fb_deferred_io_cleanup(struct fb_info *info);
 extern int fb_deferred_io_fsync(struct file *file, loff_t start,
 				loff_t end, int datasync);
 
+/*
+ * Generate callbacks for deferred I/O
+ */
+
+#define __FB_GEN_DEFAULT_DEFERRED_OPS_RDWR(__prefix, __damage_range, __mode) \
+	static ssize_t __prefix ## _defio_read(struct fb_info *info, char __user *buf, \
+					       size_t count, loff_t *ppos) \
+	{ \
+		return fb_ ## __mode ## _read(info, buf, count, ppos); \
+	} \
+	static ssize_t __prefix ## _defio_write(struct fb_info *info, const char __user *buf, \
+						size_t count, loff_t *ppos) \
+	{ \
+		unsigned long offset = *ppos; \
+		ssize_t ret = fb_ ## __mode ## _write(info, buf, count, ppos); \
+		if (ret > 0) \
+			__damage_range(info, offset, ret); \
+		return ret; \
+	}
+
+#define __FB_GEN_DEFAULT_DEFERRED_OPS_DRAW(__prefix, __damage_area, __mode) \
+	static void __prefix ## _defio_fillrect(struct fb_info *info, \
+						const struct fb_fillrect *rect) \
+	{ \
+		__mode ## _fillrect(info, rect); \
+		__damage_area(info, rect->dx, rect->dy, rect->width, rect->height); \
+	} \
+	static void __prefix ## _defio_copyarea(struct fb_info *info, \
+						const struct fb_copyarea *area) \
+	{ \
+		__mode ## _copyarea(info, area); \
+		__damage_area(info, area->dx, area->dy, area->width, area->height); \
+	} \
+	static void __prefix ## _defio_imageblit(struct fb_info *info, \
+						 const struct fb_image *image) \
+	{ \
+		__mode ## _imageblit(info, image); \
+		__damage_area(info, image->dx, image->dy, image->width, image->height); \
+	}
+
+#define FB_GEN_DEFAULT_DEFERRED_IO_OPS(__prefix, __damage_range, __damage_area) \
+	__FB_GEN_DEFAULT_DEFERRED_OPS_RDWR(__prefix, __damage_range, io) \
+	__FB_GEN_DEFAULT_DEFERRED_OPS_DRAW(__prefix, __damage_area, cfb)
+
+#define FB_GEN_DEFAULT_DEFERRED_SYS_OPS(__prefix, __damage_range, __damage_area) \
+	__FB_GEN_DEFAULT_DEFERRED_OPS_RDWR(__prefix, __damage_range, sys) \
+	__FB_GEN_DEFAULT_DEFERRED_OPS_DRAW(__prefix, __damage_area, sys)
+
+/*
+ * Initializes struct fb_ops for deferred I/O.
+ */
+
+#define __FB_DEFAULT_DEFERRED_OPS_RDWR(__prefix) \
+	.fb_read	= __prefix ## _defio_read, \
+	.fb_write	= __prefix ## _defio_write
+
+#define __FB_DEFAULT_DEFERRED_OPS_DRAW(__prefix) \
+	.fb_fillrect	= __prefix ## _defio_fillrect, \
+	.fb_copyarea	= __prefix ## _defio_copyarea, \
+	.fb_imageblit	= __prefix ## _defio_imageblit
+
+#define __FB_DEFAULT_DEFERRED_OPS_MMAP(__prefix) \
+	.fb_mmap	= fb_deferred_io_mmap
+
+#define FB_DEFAULT_DEFERRED_OPS(__prefix) \
+	__FB_DEFAULT_DEFERRED_OPS_RDWR(__prefix), \
+	__FB_DEFAULT_DEFERRED_OPS_DRAW(__prefix), \
+	__FB_DEFAULT_DEFERRED_OPS_MMAP(__prefix)
+
 static inline bool fb_be_math(struct fb_info *info)
 {
 #ifdef CONFIG_FB_FOREIGN_ENDIAN