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 #ifdef CONFIG_FRAMEBUFFER_CONSOLE_DEFERRED_TAKEOVER
  30 /* These are both protected by the console_lock */
  31 static RAW_NOTIFIER_HEAD(dummycon_output_nh);
  32 static bool dummycon_putc_called;
  33
  34 void dummycon_register_output_notifier(struct notifier_block *nb)
  35 {
  36         raw_notifier_chain_register(&dummycon_output_nh, nb);
  37
  38         if (dummycon_putc_called)
  39                 nb->notifier_call(nb, 0, NULL);
  40 }
  41
  42 void dummycon_unregister_output_notifier(struct notifier_block *nb)
  43 {
  44         raw_notifier_chain_unregister(&dummycon_output_nh, nb);
  45 }
  46
  47 static void dummycon_putc(struct vc_data *vc, int c, int ypos, int xpos)
  48 {
  49         dummycon_putc_called = true;
  50         raw_notifier_call_chain(&dummycon_output_nh, 0, NULL);
  51 }
  52
  53 static void dummycon_putcs(struct vc_data *vc, const unsigned short *s,
  54                            int count, int ypos, int xpos)
  55 {
  56         int i;
  57
  58         if (!dummycon_putc_called) {
  59                 /* Ignore erases */
  60                 for (i = 0 ; i < count; i++) {
  61                         if (s[i] != vc->vc_video_erase_char)
  62                                 break;
  63                 }
  64                 if (i == count)
  65                         return;
  66
  67                 dummycon_putc_called = true;
  68         }
  69
  70         raw_notifier_call_chain(&dummycon_output_nh, 0, NULL);
  71 }
  72
  73 static int dummycon_blank(struct vc_data *vc, int blank, int mode_switch)
  74 {
  75         /* Redraw, so that we get putc(s) for output done while blanked */
  76         return 1;
  77 }
  78 #else
  79 static void dummycon_putc(struct vc_data *vc, int c, int ypos, int xpos) { }
  80 static void dummycon_putcs(struct vc_data *vc, const unsigned short *s,
  81                            int count, int ypos, int xpos) { }
  82 static int dummycon_blank(struct vc_data *vc, int blank, int mode_switch)
  83 {
  84         return 0;
  85 }
  86 #endif
  87
  88 static const char *dummycon_startup(void)
  89 {
  90     return "dummy device";
  91 }
  92
  93 static void dummycon_init(struct vc_data *vc, int init)
  94 {
  95     vc->vc_can_do_color = 1;
  96     if (init) {
  97         vc->vc_cols = DUMMY_COLUMNS;
  98         vc->vc_rows = DUMMY_ROWS;
  99     } else
 100         vc_resize(vc, DUMMY_COLUMNS, DUMMY_ROWS);
 101 }
 102
 103 static void dummycon_deinit(struct vc_data *vc) { }
 104 static void dummycon_clear(struct vc_data *vc, int sy, int sx, int height,
 105                            int width) { }
 106 static void dummycon_cursor(struct vc_data *vc, int mode) { }
 107
 108 static bool dummycon_scroll(struct vc_data *vc, unsigned int top,
 109                             unsigned int bottom, enum con_scroll dir,
 110                             unsigned int lines)
 111 {
 112         return false;
 113 }
 114
 115 static int dummycon_switch(struct vc_data *vc)
 116 {
 117         return 0;
 118 }
 119
 120 static int dummycon_font_set(struct vc_data *vc, struct console_font *font,
 121                              unsigned int flags)
 122 {
 123         return 0;
 124 }
 125
 126 static int dummycon_font_default(struct vc_data *vc,
 127                                  struct console_font *font, char *name)
 128 {
 129         return 0;
 130 }
 131
 132 static int dummycon_font_copy(struct vc_data *vc, int con)
 133 {
 134         return 0;
 135 }
 136
 137 /*
 138  *  The console `switch' structure for the dummy console
 139  *
 140  *  Most of the operations are dummies.
 141  */
 142
 143 const struct consw dummy_con = {
 144         .owner =                THIS_MODULE,
 145         .con_startup =  dummycon_startup,
 146         .con_init =             dummycon_init,
 147         .con_deinit =   dummycon_deinit,
 148         .con_clear =    dummycon_clear,
 149         .con_putc =             dummycon_putc,
 150         .con_putcs =    dummycon_putcs,
 151         .con_cursor =   dummycon_cursor,
 152         .con_scroll =   dummycon_scroll,
 153         .con_switch =   dummycon_switch,
 154         .con_blank =    dummycon_blank,
 155         .con_font_set = dummycon_font_set,
 156         .con_font_default =     dummycon_font_default,
 157         .con_font_copy =        dummycon_font_copy,
 158 };
 159 EXPORT_SYMBOL_GPL(dummy_con);