lib/fonts: Implement font rotation

Move the core of fbcon's font-rotation code to the font library as
the new helper font_data_rotate(). The code can rotate in steps of
90°. For completeness, it also copies the glyph data for multiples
of 360°.

Bring back the memset optimization. A memset to 0 again clears the
whole glyph output buffer. Then use the internal rotation helpers on
the cleared output. Fbcon's original implementation worked like this,
but lost it during refactoring.

Replace fbcon's font-rotation code with the new implementations.
All that's left to do for fbcon is to maintain its internal fbcon
state.

v2:
- fix typos

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Helge Deller <deller@gmx.de>

2 files changed, 20 insertions, 60 deletions

diff --git a/drivers/video/fbdev/core/fbcon.h b/drivers/video/fbdev/core/fbcon.h
index 1e3c1ef84762..1793f34a6c84 100644
--- a/drivers/video/fbdev/core/fbcon.h
+++ b/drivers/video/fbdev/core/fbcon.h
@@ -86,7 +86,7 @@ struct fbcon_par {
 	const u8    *fontdata;
 	u8    *cursor_src;
 	u32    cursor_size;
-	u32    fd_size;
+	size_t fd_size;
 
 	const struct fbcon_bitops *bitops;
 };
diff --git a/drivers/video/fbdev/core/fbcon_rotate.c b/drivers/video/fbdev/core/fbcon_rotate.c
index 588dc9d6758a..74206f5a6e98 100644
--- a/drivers/video/fbdev/core/fbcon_rotate.c
+++ b/drivers/video/fbdev/core/fbcon_rotate.c
@@ -8,84 +8,44 @@
  *  more details.
  */
 
-#include <linux/module.h>
-#include <linux/slab.h>
-#include <linux/string.h>
+#include <linux/errno.h>
 #include <linux/fb.h>
 #include <linux/font.h>
-#include <linux/vt_kern.h>
-#include <linux/console.h>
-#include <asm/types.h>
+
 #include "fbcon.h"
 #include "fbcon_rotate.h"
 
 int fbcon_rotate_font(struct fb_info *info, struct vc_data *vc)
 {
 	struct fbcon_par *par = info->fbcon_par;
-	int len, err = 0;
-	int s_cellsize, d_cellsize, i;
-	const u8 *src;
-	u8 *dst;
+	unsigned char *fontbuffer;
+	int ret;
 
 	if (vc->vc_font.data == par->fontdata &&
 	    par->p->con_rotate == par->cur_rotate)
-		goto finished;
+		return 0;
 
-	src = par->fontdata = vc->vc_font.data;
+	par->fontdata = vc->vc_font.data;
 	par->cur_rotate = par->p->con_rotate;
-	len = vc->vc_font.charcount;
-	s_cellsize = font_glyph_size(vc->vc_font.width, vc->vc_font.height);
-	d_cellsize = s_cellsize;
-
-	if (par->rotate == FB_ROTATE_CW ||
-	    par->rotate == FB_ROTATE_CCW)
-		d_cellsize = font_glyph_size(vc->vc_font.height, vc->vc_font.width);
 
 	if (info->fbops->fb_sync)
 		info->fbops->fb_sync(info);
 
-	if (par->fd_size < d_cellsize * len) {
-		kfree(par->fontbuffer);
-		par->fontbuffer = NULL;
-		par->fd_size = 0;
-
-		dst = kmalloc_array(len, d_cellsize, GFP_KERNEL);
-
-		if (dst == NULL) {
-			err = -ENOMEM;
-			goto finished;
-		}
-
-		par->fd_size = d_cellsize * len;
-		par->fontbuffer = dst;
+	fontbuffer = font_data_rotate(par->p->fontdata, vc->vc_font.width,
+				      vc->vc_font.height, vc->vc_font.charcount,
+				      par->rotate, par->fontbuffer, &par->fd_size);
+	if (IS_ERR(fontbuffer)) {
+		ret = PTR_ERR(fontbuffer);
+		goto err_kfree;
 	}
 
-	dst = par->fontbuffer;
+	par->fontbuffer = fontbuffer;
 
-	switch (par->rotate) {
-	case FB_ROTATE_UD:
-		for (i = len; i--; ) {
-			font_glyph_rotate_180(src, vc->vc_font.width, vc->vc_font.height, dst);
-			src += s_cellsize;
-			dst += d_cellsize;
-		}
-		break;
-	case FB_ROTATE_CW:
-		for (i = len; i--; ) {
-			font_glyph_rotate_90(src, vc->vc_font.width, vc->vc_font.height, dst);
-			src += s_cellsize;
-			dst += d_cellsize;
-		}
-		break;
-	case FB_ROTATE_CCW:
-		for (i = len; i--; ) {
-			font_glyph_rotate_270(src, vc->vc_font.width, vc->vc_font.height, dst);
-			src += s_cellsize;
-			dst += d_cellsize;
-		}
-		break;
-	}
+	return 0;
+
+err_kfree:
+	kfree(par->fontbuffer);
+	par->fontbuffer = NULL; /* clear here to avoid output */
 
-finished:
-	return err;
+	return ret;
 }