linux.git/lib/fonts, branch master

lib/fonts: Implement font rotation

2026-04-07T15:38:07+00:00

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 
Signed-off-by: Helge Deller

lib/fonts: Refactor glyph-rotation helpers

2026-04-07T15:38:07+00:00

Change the signatures of the glyph-rotation helpers to match their
public interfaces. Drop the inline qualifier.

Rename several variables to better match their meaning. Especially
rename variables to bit_pitch (or a variant thereof) if they store
a pitch value in bits per scanline. The original code is fairly
confusing about this. Move the calculation of the bit pitch into the
new helper font_glyph_bit_pitch().

Signed-off-by: Thomas Zimmermann 
Signed-off-by: Helge Deller

lib/fonts: Refactor glyph-pattern helpers

2026-04-07T15:38:07+00:00

Change the signatures of the pattern helpers to align them with other
font-glyph helpers: use the font_glyph_ prefix and pass the glyph
buffer first.

Calculating the position of the involved bit is somewhat obfuscated
in the original implementation. Move it into the new helper
__font_glyph_pos() and use the result as array index and bit position.

Note that these bit helpers use a bit pitch, while other code uses a
byte pitch. This is intentional and required here.

v2:
- fix typos in commit message

Signed-off-by: Thomas Zimmermann 
Signed-off-by: Helge Deller

lib/fonts: Implement glyph rotation

2026-04-07T15:38:07+00:00

Move the glyph rotation helpers from fbcon to the font library. Wrap them
behind clean interfaces. Also clear the output memory to zero. Previously,
the implementation relied on the caller to do that.

Go through the fbcon code and callers of the glyph-rotation helpers. In
addition to the font rotation, there's also the cursor code, which uses
the rotation helpers.

The font-rotation relied on a single memset to zero for the whole font.
This is now multiple memsets on each glyph. This will be sorted out when
the font library also implements font rotation.

Building glyph rotation in the font library still depends on
CONFIG_FRAMEBUFFER_CONSOLE_ROTATION=y. If we get more users of the code,
we can still add a dedicated Kconfig symbol to the font library.

No changes have been made to the actual implementation of the rotate_*()
and pattern_*() functions. These will be refactored as separate changes.

v2:
- fix typos

Signed-off-by: Thomas Zimmermann 
Signed-off-by: Helge Deller

lib/fonts: Clean up Makefile

2026-04-07T15:38:07+00:00

Simplify the Makefile. Drop font-obj-y and sort the fonts by dictionary
order. Done in preparation for supporting optional font rotation.

v2:
- sort Makefile font entries by Family/Size in ascending order (Geert, Jiri)

Signed-off-by: Thomas Zimmermann 
Signed-off-by: Helge Deller

lib/fonts: Provide helpers for calculating glyph pitch and size

2026-04-07T15:38:07+00:00

Implement pitch and size calculation for a single font glyph in the
new helpers font_glyph_pitch() and font_glyph_size(). Replace the
instances where the calculations are open-coded.

Note that in the case of fbcon console rotation, the parameters for
a glyph's width and height might be reversed. This is intentional.

v2:
- fix typos in commit message

Signed-off-by: Thomas Zimmermann 
Signed-off-by: Helge Deller

lib/fonts: Remove internal symbols and macros from public header file

2026-03-09T14:47:21+00:00

Define access macros for font_data_t in fonts.c. Define struct font_data
and declare most of the font symbols in the internal header font.h, where
they can only be seen by the font code.

Also move font indices into internal font.h. They appear to be unused
though. There is m86k assembly code that operates on the idx field, so
leave them in place for now.

List all built-in fonts in a separate section in the public header file.

v2:
- do not add config guards around font symbols (Helge)
- keep declaration of built-in fonts in public header

Signed-off-by: Thomas Zimmermann 
Signed-off-by: Helge Deller

lib/fonts: Store font data for user space with font_data_export()

2026-03-09T14:47:21+00:00

Add font_data_export() and update consoles to use it.

The helper font_data_export() is based on code in fbcon_get_font().
It extends the size of a single glyph to match the requested vpitch,
which us usually 32 bytes for fonts from user space. Internal fonts
have a pitch according to the glyph's height.

The implementation of font_data_export() differs in several ways from
the original code. The original implementation distinguished between
different pitches of the font data. This is not necessary as the pitch
is a parameter in the copying.

There was also special handling for a font pitch of 3 bytes, which got
expanded to 4 bytes (with trailing bits on each scanline). The logic
originated from long before git history exists even in the historical
tree. So it is not clear why this was implemented. It is not what user
space expects. The setfont utitlity loads font with 3-bytes pitches and
expects to read such fonts with a 3-byte pitch. For any font width, the
font pitch is always the width extended to the next multiple of 8. See
[1] for the user-space font-reading code.

With the changes to handling the font pitches, font_data_export() replaces
the original code's various special cases with a single copying logic.

v3:
- fix typos (Helge)

Signed-off-by: Thomas Zimmermann 
Link: https://github.com/legionus/kbd/blob/v2.9.0/src/libkfont/kdfontop.c#L73 # [1]
Signed-off-by: Helge Deller

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

2026-03-09T14:47:21+00:00

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 
Signed-off-by: Helge Deller

lib/fonts: Compare font data for equality with font_data_is_equal()

2026-03-09T14:47:21+00:00

Add font_data_is_equal() and update consoles to use it.

Font data is equal if it has the same size and contains the same values
on all bytes. Only fbcon uses a crc32 checksum. If set in both operands
the checksums have to be equal.

The new helper also guarantees to not compare internal fonts against
fonts from user space. Internal fonts cannot be ref-counted, so making
them equal to user-space fonts with the same byte sequence results in
undefined behavior.

The test only compares data buffers. Their interpretation is up each
console. Therefore remove a width test in fbcon_set_font().

v3:
- rebase onto font_data_{get,put}()

Signed-off-by: Thomas Zimmermann 
Signed-off-by: Helge Deller