fbcon: Avoid using FNTCHARCNT() and hard-coded built-in font charcount

For user-provided fonts, the framebuffer layer is using a magic
negative-indexing macro, FNTCHARCNT(), to keep track of their number of
characters:

	#define FNTCHARCNT(fd)	(((int *)(fd))[-3])

For built-in fonts, it is using hard-coded values (256). This results in
something like the following:

		map.length = (ops->p->userfont) ?
			FNTCHARCNT(ops->p->fontdata) : 256;

This is unsatisfactory. In fact, there is already a `charcount` field in
our virtual console descriptor (see `struct console_font` inside `struct
vc_data`), let us use it:

		map.length = vc->vc_font.charcount;

Recently we added a `charcount` field to `struct font_desc`. Use it to set
`vc->vc_font.charcount` properly. The idea is:

  - We only use FNTCHARCNT() on `vc->vc_font.data` and `p->fontdata`.
    Assume FNTCHARCNT() is working as intended;
  - Whenever `vc->vc_font.data` is set, also set `vc->vc_font.charcount`
    properly;
  - We can now replace `FNTCHARCNT(vc->vc_font.data)` with
    `vc->vc_font.charcount`;
  - Since `p->fontdata` always point to the same font data buffer with
    `vc->vc_font.data`, we can also replace `FNTCHARCNT(p->fontdata)` with
    `vc->vc_font.charcount`.

In conclusion, set `vc->vc_font.charcount` properly in fbcon_startup(),
fbcon_init(), fbcon_set_disp() and fbcon_do_set_font(), then replace
FNTCHARCNT() with `vc->vc_font.charcount`. No more if-else between
negative-indexing macros and hard-coded values.

Do not include <linux/font.h> in fbcon_rotate.c and tileblit.c, since they
no longer need it.

Depends on patch "Fonts: Add charcount field to font_desc".

Suggested-by: Daniel Vetter <daniel@ffwll.ch>
Signed-off-by: Peilin Ye <yepeilin.cs@gmail.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/e460a5780e54e3022661d5f09555144583b4cc59.1605169912.git.yepeilin.cs@gmail.com

1 files changed, 1 insertions, 2 deletions

diff --git a/drivers/video/fbdev/core/fbcon_rotate.c b/drivers/video/fbdev/core/fbcon_rotate.c
index ac72d4f85f7d..ef1d421c261a 100644
--- a/drivers/video/fbdev/core/fbcon_rotate.c
+++ b/drivers/video/fbdev/core/fbcon_rotate.c
@@ -14,7 +14,6 @@
 #include <linux/fb.h>
 #include <linux/vt_kern.h>
 #include <linux/console.h>
-#include <linux/font.h>
 #include <asm/types.h>
 #include "fbcon.h"
 #include "fbcon_rotate.h"
@@ -33,7 +32,7 @@ static int fbcon_rotate_font(struct fb_info *info, struct vc_data *vc)
 
 	src = ops->fontdata = vc->vc_font.data;
 	ops->cur_rotate = ops->p->con_rotate;
-	len = (!ops->p->userfont) ? 256 : FNTCHARCNT(src);
+	len = vc->vc_font.charcount;
 	s_cellsize = ((vc->vc_font.width + 7)/8) *
 		vc->vc_font.height;
 	d_cellsize = s_cellsize;