Make console charset translation optional

By turning off the new CONSOLE_TRANSLATIONS option and dropping the
associated code and tables from the kernel, we can save about 7KiB.

Taken from linux-tiny project by Tim Bird and mangled further by dwmw2.

Signed-off-by: Tim Bird <tim.bird@am.sony.com>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>

drivers/char/Kconfig

@@ -36,6 +36,14 @@ config VT
 	  If unsure, say Y, or else you won't be able to do much with your new
 	  shiny Linux system :-)
 
+config CONSOLE_TRANSLATIONS
+	depends on VT
+	default y
+	bool "Enable character translations in console" if EMBEDDED
+	---help---
+	  This enables support for font mapping and Unicode translation
+	  on virtual consoles.
+
 config VT_CONSOLE
 	bool "Support for console on virtual terminal" if EMBEDDED
 	depends on VT

drivers/char/Makefile

@@ -12,8 +12,8 @@ obj-y	 += mem.o random.o tty_io.o n_tty.o tty_ioctl.o
 obj-$(CONFIG_LEGACY_PTYS)	+= pty.o
 obj-$(CONFIG_UNIX98_PTYS)	+= pty.o
 obj-y				+= misc.o
-obj-$(CONFIG_VT)		+= vt_ioctl.o vc_screen.o consolemap.o \
-				   consolemap_deftbl.o selection.o keyboard.o
+obj-$(CONFIG_VT)		+= vt_ioctl.o vc_screen.o selection.o keyboard.o
+obj-$(CONFIG_CONSOLE_TRANSLATIONS) += consolemap.o consolemap_deftbl.o
 obj-$(CONFIG_HW_CONSOLE)	+= vt.o defkeymap.o
 obj-$(CONFIG_AUDIT)		+= tty_audit.o
 obj-$(CONFIG_MAGIC_SYSRQ)	+= sysrq.o

drivers/char/vt.c

@@ -2208,7 +2208,7 @@ static int do_con_write(struct tty_struct *tty, const unsigned char *buf, int co
 			c = 0xfffd;
 		    tc = c;
 		} else {	/* no utf or alternate charset mode */
-		    tc = vc->vc_translate[vc->vc_toggle_meta ? (c | 0x80) : c];
+		    tc = vc_translate(vc, c);
 		}
 
 		param.c = tc;

include/linux/consolemap.h

@@ -3,13 +3,17 @@
  *
  * Interface between console.c, selection.c  and consolemap.c
  */
+#ifndef __LINUX_CONSOLEMAP_H__
+#define __LINUX_CONSOLEMAP_H__
+
 #define LAT1_MAP 0
 #define GRAF_MAP 1
 #define IBMPC_MAP 2
 #define USER_MAP 3
 
 #include <linux/types.h>
 
+#ifdef CONFIG_CONSOLE_TRANSLATIONS
 struct vc_data;
 
 extern u16 inverse_translate(struct vc_data *conp, int glyph, int use_unicode);
@@ -18,3 +22,13 @@ extern int conv_uni_to_pc(struct vc_data *conp, long ucs);
 extern u32 conv_8bit_to_uni(unsigned char c);
 extern int conv_uni_to_8bit(u32 uni);
 void console_map_init(void);
+#else
+#define inverse_translate(conp, glyph, uni) ((uint16_t)glyph)
+#define set_translate(m, vc) ((unsigned short *)NULL)
+#define conv_uni_to_pc(conp, ucs) ((int) (ucs > 0xff ? -1: ucs))
+#define conv_8bit_to_uni(c) ((uint32_t)(c))
+#define conv_uni_to_8bit(c) ((int) ((c) & 0xff))
+#define console_map_init(c) do { ; } while (0)
+#endif /* CONFIG_CONSOLE_TRANSLATIONS */
+
+#endif /* __LINUX_CONSOLEMAP_H__ */

include/linux/vt_kern.h

@@ -12,6 +12,7 @@
 #include <linux/mutex.h>
 #include <linux/console_struct.h>
 #include <linux/mm.h>
+#include <linux/consolemap.h>
 
 /*
  * Presently, a lot of graphics programs do not restore the contents of
@@ -54,6 +55,7 @@ void redraw_screen(struct vc_data *vc, int is_switch);
 struct tty_struct;
 int tioclinux(struct tty_struct *tty, unsigned long arg);
 
+#ifdef CONFIG_CONSOLE_TRANSLATIONS
 /* consolemap.c */
 
 struct unimapinit;
@@ -71,6 +73,23 @@ void con_free_unimap(struct vc_data *vc);
 void con_protect_unimap(struct vc_data *vc, int rdonly);
 int con_copy_unimap(struct vc_data *dst_vc, struct vc_data *src_vc);
 
+#define vc_translate(vc, c) ((vc)->vc_translate[(c) |			\
+					(vc)->vc_toggle_meta ? 0x80 : 0])
+#else
+#define con_set_trans_old(arg) (0)
+#define con_get_trans_old(arg) (-EINVAL)
+#define con_set_trans_new(arg) (0)
+#define con_get_trans_new(arg) (-EINVAL)
+#define con_clear_unimap(vc, ui) (0)
+#define con_set_unimap(vc, ct, list) (0)
+#define con_set_default_unimap(vc) (0)
+#define con_copy_unimap(d, s) (0)
+#define con_get_unimap(vc, ct, uct, list) (-EINVAL)
+#define con_free_unimap(vc) do { ; } while (0)
+
+#define vc_translate(vc, c) (c)
+#endif
+
 /* vt.c */
 int vt_waitactive(int vt);
 void change_console(struct vc_data *new_vc);