drivers/video/console/dummycon.c

   1 /*
   2  *  linux/drivers/video/dummycon.c -- A dummy console driver
   3  *
   4  *  To be used if there's no other console driver (e.g. for plain VGA text)
   5  *  available, usually until fbcon takes console over.
   6  */
   7
   8 #include <linux/types.h>
   9 #include <linux/kdev_t.h>
  10 #include <linux/console.h>
  11 #include <linux/vt_kern.h>
  12 #include <linux/screen_info.h>
  13 #include <linux/init.h>
  14 #include <linux/module.h>
  15
  16 /*
  17  *  Dummy console driver
  18  */
  19
  20 #if defined(__arm__)
  21 #define DUMMY_COLUMNS   screen_info.orig_video_cols
  22 #define DUMMY_ROWS      screen_info.orig_video_lines
  23 #else
  24 /* set by Kconfig. Use 80x25 for 640x480 and 160x64 for 1280x1024 */
  25 #define DUMMY_COLUMNS   CONFIG_DUMMY_CONSOLE_COLUMNS
  26 #define DUMMY_ROWS      CONFIG_DUMMY_CONSOLE_ROWS
  27 #endif
  28
  29 static const char *dummycon_startup(void)
  30 {
  31     return "dummy device";
  32 }
  33
  34 static void dummycon_init(struct vc_data *vc, int init)
  35 {
  36     vc->vc_can_do_color = 1;
  37     if (init) {
  38         vc->vc_cols = DUMMY_COLUMNS;
  39         vc->vc_rows = DUMMY_ROWS;
  40     } else
  41         vc_resize(vc, DUMMY_COLUMNS, DUMMY_ROWS);
  42 }
  43
  44 static void dummycon_deinit(struct vc_data *vc) { }
  45 static void dummycon_clear(struct vc_data *vc, int sy, int sx, int height,
  46                            int width) { }
  47 static void dummycon_putc(struct vc_data *vc, int c, int ypos, int xpos) { }
  48 static void dummycon_putcs(struct vc_data *vc, const unsigned short *s,
  49                            int count, int ypos, int xpos) { }
  50 static void dummycon_cursor(struct vc_data *vc, int mode) { }
  51
  52 static bool dummycon_scroll(struct vc_data *vc, unsigned int top,
  53                             unsigned int bottom, enum con_scroll dir,
  54                             unsigned int lines)
  55 {
  56         return false;
  57 }
  58
  59 static int dummycon_switch(struct vc_data *vc)
  60 {
  61         return 0;
  62 }
  63
  64 static int dummycon_blank(struct vc_data *vc, int blank, int mode_switch)
  65 {
  66         return 0;
  67 }
  68
  69 static int dummycon_font_set(struct vc_data *vc, struct console_font *font,
  70                              unsigned int flags)
  71 {
  72         return 0;
  73 }
  74
  75 static int dummycon_font_default(struct vc_data *vc,
  76                                  struct console_font *font, char *name)
  77 {
  78         return 0;
  79 }
  80
  81 static int dummycon_font_copy(struct vc_data *vc, int con)
  82 {
  83         return 0;
  84 }
  85
  86 /*
  87  *  The console `switch' structure for the dummy console
  88  *
  89  *  Most of the operations are dummies.
  90  */
  91
  92 const struct consw dummy_con = {
  93         .owner =                THIS_MODULE,
  94         .con_startup =  dummycon_startup,
  95         .con_init =             dummycon_init,
  96         .con_deinit =   dummycon_deinit,
  97         .con_clear =    dummycon_clear,
  98         .con_putc =             dummycon_putc,
  99         .con_putcs =    dummycon_putcs,
 100         .con_cursor =   dummycon_cursor,
 101         .con_scroll =   dummycon_scroll,
 102         .con_switch =   dummycon_switch,
 103         .con_blank =    dummycon_blank,
 104         .con_font_set = dummycon_font_set,
 105         .con_font_default =     dummycon_font_default,
 106         .con_font_copy =        dummycon_font_copy,
 107 };
 108 EXPORT_SYMBOL_GPL(dummy_con);