[PATCH v3 07/13] lib/fonts: Store font data as font_data_t; update consoles

[Thomas Zimmermann <tzimmermann@suse.de>]

Store font data as pointer to font_data_t instead of unsigned char.
Update consoles.

Pointers to font data refer to the raw data. There is a hidden header
before the data that contains additional state. Document the existing
layout and semantics of font_data_t.

The data field in struct vc_font can be used by any console. Therefore
it still points to plain data without the additional header. Fbcon sets
its value from struct fbcon_display.fontdata. Hence, update the size
test in fbcon_resize() to use struct fbcon_display.fontdata instead of
struct vc_font.data.

v3:
- fix typos (Helge)
v2:
- 'Font lookup' -> 'Font description' in <linux/font.h>

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/video/console/newport_con.c | 17 ++++++-----
 drivers/video/fbdev/core/fbcon.c    | 44 ++++++++++++++++-----------
 drivers/video/fbdev/core/fbcon.h    |  3 +-
 include/linux/font.h                | 47 ++++++++++++++++++++++++++++-
 4 files changed, 84 insertions(+), 27 deletions(-)

diff --git a/drivers/video/console/newport_con.c b/drivers/video/console/newport_con.c
index e2922caa8685..9b9ed1940404 100644
--- a/drivers/video/console/newport_con.c
+++ b/drivers/video/console/newport_con.c
@@ -33,9 +33,9 @@
 
 #define NEWPORT_LEN	0x10000
 
-#define FONT_DATA ((unsigned char *)font_vga_8x16.data)
+#define FONT_DATA font_vga_8x16.data
 
-static unsigned char *font_data[MAX_NR_CONSOLES];
+static font_data_t *font_data[MAX_NR_CONSOLES];
 
 static struct newport_regs *npregs;
 static unsigned long newport_addr;
@@ -370,9 +370,9 @@ static void newport_clear(struct vc_data *vc, unsigned int sy, unsigned int sx,
 static void newport_putc(struct vc_data *vc, u16 charattr, unsigned int ypos,
 			 unsigned int xpos)
 {
-	unsigned char *p;
+	const unsigned char *p;
 
-	p = &font_data[vc->vc_num][(charattr & 0xff) << 4];
+	p = &font_data_buf(font_data[vc->vc_num])[(charattr & 0xff) << 4];
 	charattr = (charattr >> 8) & 0xff;
 	xpos <<= 3;
 	ypos <<= 4;
@@ -400,7 +400,7 @@ static void newport_putcs(struct vc_data *vc, const u16 *s,
 			  unsigned int count, unsigned int ypos,
 			  unsigned int xpos)
 {
-	unsigned char *p;
+	const unsigned char *p;
 	unsigned int i;
 	u16 charattr;
 
@@ -424,7 +424,7 @@ static void newport_putcs(struct vc_data *vc, const u16 *s,
 				 NPORT_DMODE0_L32);
 
 	for (i = 0; i < count; i++, xpos += 8) {
-		p = &font_data[vc->vc_num][(scr_readw(s++) & 0xff) << 4];
+		p = &font_data_buf(font_data[vc->vc_num])[(scr_readw(s++) & 0xff) << 4];
 
 		newport_wait(npregs);
 
@@ -503,7 +503,8 @@ static int newport_set_font(int unit, const struct console_font *op,
 	int h = op->height;
 	int size = h * op->charcount;
 	int i;
-	unsigned char *new_data, *data = op->data, *p;
+	font_data_t *new_data;
+	unsigned char *data = op->data, *p;
 
 	/* ladis: when I grow up, there will be a day... and more sizes will
 	 * be supported ;-) */
@@ -519,7 +520,7 @@ static int newport_set_font(int unit, const struct console_font *op,
 	REFCOUNT(new_data) = 0;	/* usage counter */
 	FNTSUM(new_data) = 0;
 
-	p = new_data;
+	p = (unsigned char *)font_data_buf(new_data);
 	for (i = 0; i < op->charcount; i++) {
 		memcpy(p, data, h);
 		data += 32;
diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c
index 103e91c8d874..8d7840b9ebad 100644
--- a/drivers/video/fbdev/core/fbcon.c
+++ b/drivers/video/fbdev/core/fbcon.c
@@ -1019,8 +1019,10 @@ static const char *fbcon_startup(void)
 						info->pixmap.blit_y);
 		vc->vc_font.width = font->width;
 		vc->vc_font.height = font->height;
-		vc->vc_font.data = (void *)(p->fontdata = font->data);
+		vc->vc_font.data = font_data_buf(font->data);
 		vc->vc_font.charcount = font->charcount;
+
+		p->fontdata = font->data;
 	}
 
 	cols = FBCON_SWAP(par->rotate, info->var.xres, info->var.yres);
@@ -1078,11 +1080,12 @@ static void fbcon_init(struct vc_data *vc, bool init)
 		if (t->fontdata) {
 			struct vc_data *fvc = vc_cons[fg_console].d;
 
-			vc->vc_font.data = (void *)(p->fontdata =
-						    fvc->vc_font.data);
+			vc->vc_font.data = fvc->vc_font.data;
 			vc->vc_font.width = fvc->vc_font.width;
 			vc->vc_font.height = fvc->vc_font.height;
 			vc->vc_font.charcount = fvc->vc_font.charcount;
+
+			p->fontdata = t->fontdata;
 			p->userfont = t->userfont;
 
 			if (p->userfont)
@@ -1097,8 +1100,10 @@ static void fbcon_init(struct vc_data *vc, bool init)
 							info->pixmap.blit_y);
 			vc->vc_font.width = font->width;
 			vc->vc_font.height = font->height;
-			vc->vc_font.data = (void *)(p->fontdata = font->data);
+			vc->vc_font.data = font_data_buf(font->data);
 			vc->vc_font.charcount = font->charcount;
+
+			p->fontdata = font->data;
 		}
 	}
 
@@ -1409,11 +1414,12 @@ static void fbcon_set_disp(struct fb_info *info, struct fb_var_screeninfo *var,
 	svc = *default_mode;
 	t = &fb_display[svc->vc_num];
 
-	if (!vc->vc_font.data) {
-		vc->vc_font.data = (void *)(p->fontdata = t->fontdata);
+	if (!p->fontdata) {
+		vc->vc_font.data = font_data_buf(t->fontdata);
 		vc->vc_font.width = (*default_mode)->vc_font.width;
 		vc->vc_font.height = (*default_mode)->vc_font.height;
 		vc->vc_font.charcount = (*default_mode)->vc_font.charcount;
+		p->fontdata = t->fontdata;
 		p->userfont = t->userfont;
 		if (p->userfont)
 			REFCOUNT(p->fontdata)++;
@@ -2047,7 +2053,7 @@ static int fbcon_resize(struct vc_data *vc, unsigned int width,
 	struct fb_var_screeninfo var = info->var;
 	int x_diff, y_diff, virt_w, virt_h, virt_fw, virt_fh;
 
-	if (p->userfont && FNTSIZE(vc->vc_font.data)) {
+	if (p->userfont && FNTSIZE(p->fontdata)) {
 		unsigned int size = vc_font_size(&vc->vc_font);
 
 		/*
@@ -2057,7 +2063,7 @@ static int fbcon_resize(struct vc_data *vc, unsigned int width,
 		 * charcount can change and cannot be used to determine the
 		 * font data allocated size.
 		 */
-		if (!size || size > FNTSIZE(vc->vc_font.data))
+		if (!size || size > FNTSIZE(p->fontdata))
 			return -EINVAL;
 	}
 
@@ -2281,7 +2287,8 @@ static bool fbcon_blank(struct vc_data *vc, enum vesa_blank_mode blank,
 
 static int fbcon_get_font(struct vc_data *vc, struct console_font *font, unsigned int vpitch)
 {
-	const u8 *fontdata = vc->vc_font.data;
+	struct fbcon_display *p = &fb_display[vc->vc_num];
+	font_data_t *fontdata = p->fontdata;
 	u8 *data = font->data;
 	int i, j;
 
@@ -2406,16 +2413,18 @@ static void set_vc_hi_font(struct vc_data *vc, bool set)
 }
 
 static int fbcon_do_set_font(struct vc_data *vc, int w, int h, int charcount,
-			     const u8 * data, int userfont)
+			     font_data_t *data, int userfont)
 {
 	struct fb_info *info = fbcon_info_from_console(vc->vc_num);
 	struct fbcon_par *par = info->fbcon_par;
 	struct fbcon_display *p = &fb_display[vc->vc_num];
 	int resize, ret, old_userfont, old_width, old_height, old_charcount;
+	font_data_t *old_fontdata = p->fontdata;
 	const u8 *old_data = vc->vc_font.data;
 
 	resize = (w != vc->vc_font.width) || (h != vc->vc_font.height);
-	vc->vc_font.data = (void *)(p->fontdata = data);
+	p->fontdata = data;
+	vc->vc_font.data = font_data_buf(p->fontdata);
 	old_userfont = p->userfont;
 	if ((p->userfont = userfont))
 		REFCOUNT(data)++;
@@ -2448,12 +2457,12 @@ static int fbcon_do_set_font(struct vc_data *vc, int w, int h, int charcount,
 		update_screen(vc);
 	}
 
-	if (old_userfont && (--REFCOUNT(old_data) == 0))
-		kfree(old_data - FONT_EXTRA_WORDS * sizeof(int));
+	if (old_userfont && (--REFCOUNT(old_fontdata) == 0))
+		kfree(old_fontdata - FONT_EXTRA_WORDS * sizeof(int));
 	return 0;
 
 err_out:
-	p->fontdata = old_data;
+	p->fontdata = old_fontdata;
 	vc->vc_font.data = old_data;
 
 	if (userfont) {
@@ -2483,7 +2492,8 @@ static int fbcon_set_font(struct vc_data *vc, const struct console_font *font,
 	int h = font->height;
 	int size, alloc_size;
 	int i, csum;
-	u8 *new_data, *data = font->data;
+	font_data_t *new_data;
+	u8 *data = font->data;
 	int pitch = PITCH(font->width);
 
 	/* Is there a reason why fbconsole couldn't handle any charcount >256?
@@ -2522,13 +2532,13 @@ static int fbcon_set_font(struct vc_data *vc, const struct console_font *font,
 	if (!new_data)
 		return -ENOMEM;
 
-	memset(new_data, 0, FONT_EXTRA_WORDS * sizeof(int));
+	memset((u8 *)new_data, 0, FONT_EXTRA_WORDS * sizeof(int));
 
 	new_data += FONT_EXTRA_WORDS * sizeof(int);
 	FNTSIZE(new_data) = size;
 	REFCOUNT(new_data) = 0;	/* usage counter */
 	for (i=0; i< charcount; i++) {
-		memcpy(new_data + i*h*pitch, data +  i*vpitch*pitch, h*pitch);
+		memcpy((u8 *)new_data + i * h * pitch, data + i * vpitch * pitch, h * pitch);
 	}
 
 	/* Since linux has a nice crc32 function use it for counting font
diff --git a/drivers/video/fbdev/core/fbcon.h b/drivers/video/fbdev/core/fbcon.h
index 3f4386a40237..d26ee7860cf5 100644
--- a/drivers/video/fbdev/core/fbcon.h
+++ b/drivers/video/fbdev/core/fbcon.h
@@ -11,6 +11,7 @@
 #ifndef _VIDEO_FBCON_H
 #define _VIDEO_FBCON_H
 
+#include <linux/font.h>
 #include <linux/types.h>
 #include <linux/vt_buffer.h>
 #include <linux/vt_kern.h>
@@ -25,7 +26,7 @@
 
 struct fbcon_display {
     /* Filled in by the low-level console driver */
-    const u_char *fontdata;
+    font_data_t *fontdata;
     int userfont;                   /* != 0 if fontdata kmalloc()ed */
 #ifdef CONFIG_FRAMEBUFFER_CONSOLE_LEGACY_ACCELERATION
     u_short scrollmode;             /* Scroll Method, use fb_scrollmode() */
diff --git a/include/linux/font.h b/include/linux/font.h
index d929c5fa32ca..746a0996a018 100644
--- a/include/linux/font.h
+++ b/include/linux/font.h
@@ -13,12 +13,57 @@
 
 #include <linux/types.h>
 
+/*
+ * font_data_t and helpers
+ */
+
+/**
+ * font_data_t - Raw font data
+ *
+ * Values of type font_data_t store a pointer to raw font data. The format
+ * is monochrome. Each bit sets a pixel of a stored glyph. Font data does
+ * not store geometry information for the individual glyphs. Users of the
+ * font have to store glyph size, pitch and character count separately.
+ *
+ * Font data in font_data_t is not equivalent to raw u8. Each pointer stores
+ * an additional hidden header before the font data. The layout is
+ *
+ * +------+-----------------------------+
+ * | -16  |  CRC32 Checksum (optional)  |
+ * | -12  |  <Unused>                   |
+ * |  -8  |  Number of data bytes       |
+ * |  -4  |  Reference count            |
+ * +------+-----------------------------+
+ * |   0  |  Data buffer                |
+ * |  ... |                             |
+ * +------+-----------------------------+
+ *
+ * Use helpers to access font_data_t. Use font_data_buf() to get the stored data.
+ */
+typedef const unsigned char font_data_t;
+
+/**
+ * font_data_buf() - Returns the font data as raw bytes
+ * @fd: The font data
+ *
+ * Returns:
+ * The raw font data. The provided buffer is read-only.
+ */
+static inline const unsigned char *font_data_buf(font_data_t *fd)
+{
+	return (const unsigned char *)fd;
+}
+
+/*
+ * Font description
+ */
+
 struct font_desc {
     int idx;
     const char *name;
     unsigned int width, height;
     unsigned int charcount;
-    const void *data;
+    font_data_t *data;
     int pref;
 };
 
-- 
2.53.0