lib/fonts: Create font_data_t from struct console_font with font_data_import()

Add font_data_import() and update consoles to use it.

The implementation of font_data_import() is based on code from fbcon,
which supports overflow checks and crc32 checksums. Fbcon uses the crc32
checksum.

Newport_con now implements the same overflow checks as fbcon. As before,
this console does not support checksums, which are optional. Newport_con
can now also handle input font data with a vertical pitch other than 32
bytes. (The vertical pitch is the offset between two glyphs in the font
data.)

As an internal change, remove the const qualifier from the data field
if struct font_data. This allows font_data_import() to write the data
without type casting. For all users of the font data via font_data_t,
the stored data is still read only.

v3:
- fix typos

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

1 files changed, 5 insertions, 1 deletions

diff --git a/include/linux/font.h b/include/linux/font.h
index 58bf3c64cabb..3eb4818402c5 100644
--- a/include/linux/font.h
+++ b/include/linux/font.h
@@ -13,6 +13,8 @@
 
 #include <linux/types.h>
 
+struct console_font;
+
 /*
  * font_data_t and helpers
  */
@@ -54,6 +56,8 @@ static inline const unsigned char *font_data_buf(font_data_t *fd)
 	return (const unsigned char *)fd;
 }
 
+font_data_t *font_data_import(const struct console_font *font, unsigned int vpitch,
+			      u32 (*calc_csum)(u32, const void *, size_t));
 void font_data_get(font_data_t *fd);
 bool font_data_put(font_data_t *fd);
 unsigned int font_data_size(font_data_t *fd);
@@ -124,7 +128,7 @@ extern const struct font_desc *get_default_font(int xres, int yres,
 
 struct font_data {
 	unsigned int extra[FONT_EXTRA_WORDS];
-	const unsigned char data[];
+	unsigned char data[];
 } __packed;
 
 #endif /* _VIDEO_FONT_H */