Line data    Source code

       1             : // SPDX-License-Identifier: GPL-2.0-only
       2             : /*
       3             :  *  linux/drivers/video/dummycon.c -- A dummy console driver
       4             :  *
       5             :  *  To be used if there's no other console driver (e.g. for plain VGA text)
       6             :  *  available, usually until fbcon takes console over.
       7             :  */
       8             : 
       9             : #include <linux/types.h>
      10             : #include <linux/kdev_t.h>
      11             : #include <linux/console.h>
      12             : #include <linux/vt_kern.h>
      13             : #include <linux/screen_info.h>
      14             : #include <linux/init.h>
      15             : #include <linux/module.h>
      16             : 
      17             : /*
      18             :  *  Dummy console driver
      19             :  */
      20             : 
      21             : #if defined(__arm__)
      22             : #define DUMMY_COLUMNS   screen_info.orig_video_cols
      23             : #define DUMMY_ROWS      screen_info.orig_video_lines
      24             : #else
      25             : /* set by Kconfig. Use 80x25 for 640x480 and 160x64 for 1280x1024 */
      26             : #define DUMMY_COLUMNS   CONFIG_DUMMY_CONSOLE_COLUMNS
      27             : #define DUMMY_ROWS      CONFIG_DUMMY_CONSOLE_ROWS
      28             : #endif
      29             : 
      30             : #ifdef CONFIG_FRAMEBUFFER_CONSOLE_DEFERRED_TAKEOVER
      31             : /* These are both protected by the console_lock */
      32             : static RAW_NOTIFIER_HEAD(dummycon_output_nh);
      33             : static bool dummycon_putc_called;
      34             : 
      35             : void dummycon_register_output_notifier(struct notifier_block *nb)
      36             : {
      37             :         WARN_CONSOLE_UNLOCKED();
      38             : 
      39             :         raw_notifier_chain_register(&dummycon_output_nh, nb);
      40             : 
      41             :         if (dummycon_putc_called)
      42             :                 nb->notifier_call(nb, 0, NULL);
      43             : }
      44             : 
      45             : void dummycon_unregister_output_notifier(struct notifier_block *nb)
      46             : {
      47             :         WARN_CONSOLE_UNLOCKED();
      48             : 
      49             :         raw_notifier_chain_unregister(&dummycon_output_nh, nb);
      50             : }
      51             : 
      52             : static void dummycon_putc(struct vc_data *vc, int c, int ypos, int xpos)
      53             : {
      54             :         WARN_CONSOLE_UNLOCKED();
      55             : 
      56             :         dummycon_putc_called = true;
      57             :         raw_notifier_call_chain(&dummycon_output_nh, 0, NULL);
      58             : }
      59             : 
      60             : static void dummycon_putcs(struct vc_data *vc, const unsigned short *s,
      61             :                            int count, int ypos, int xpos)
      62             : {
      63             :         int i;
      64             : 
      65             :         if (!dummycon_putc_called) {
      66             :                 /* Ignore erases */
      67             :                 for (i = 0 ; i < count; i++) {
      68             :                         if (s[i] != vc->vc_video_erase_char)
      69             :                                 break;
      70             :                 }
      71             :                 if (i == count)
      72             :                         return;
      73             : 
      74             :                 dummycon_putc_called = true;
      75             :         }
      76             : 
      77             :         raw_notifier_call_chain(&dummycon_output_nh, 0, NULL);
      78             : }
      79             : 
      80             : static int dummycon_blank(struct vc_data *vc, int blank, int mode_switch)
      81             : {
      82             :         /* Redraw, so that we get putc(s) for output done while blanked */
      83             :         return 1;
      84             : }
      85             : #else
      86           0 : static void dummycon_putc(struct vc_data *vc, int c, int ypos, int xpos) { }
      87          54 : static void dummycon_putcs(struct vc_data *vc, const unsigned short *s,
      88          54 :                            int count, int ypos, int xpos) { }
      89           0 : static int dummycon_blank(struct vc_data *vc, int blank, int mode_switch)
      90             : {
      91           0 :         return 0;
      92             : }
      93             : #endif
      94             : 
      95           1 : static const char *dummycon_startup(void)
      96             : {
      97           1 :     return "dummy device";
      98             : }
      99             : 
     100           6 : static void dummycon_init(struct vc_data *vc, int init)
     101             : {
     102           6 :     vc->vc_can_do_color = 1;
     103           6 :     if (init) {
     104           6 :         vc->vc_cols = DUMMY_COLUMNS;
     105           6 :         vc->vc_rows = DUMMY_ROWS;
     106             :     } else
     107           0 :         vc_resize(vc, DUMMY_COLUMNS, DUMMY_ROWS);
     108           6 : }
     109             : 
     110           0 : static void dummycon_deinit(struct vc_data *vc) { }
     111           0 : static void dummycon_clear(struct vc_data *vc, int sy, int sx, int height,
     112           0 :                            int width) { }
     113          33 : static void dummycon_cursor(struct vc_data *vc, int mode) { }
     114             : 
     115           0 : static bool dummycon_scroll(struct vc_data *vc, unsigned int top,
     116             :                             unsigned int bottom, enum con_scroll dir,
     117             :                             unsigned int lines)
     118             : {
     119           0 :         return false;
     120             : }
     121             : 
     122           2 : static int dummycon_switch(struct vc_data *vc)
     123             : {
     124           2 :         return 0;
     125             : }
     126             : 
     127             : /*
     128             :  *  The console `switch' structure for the dummy console
     129             :  *
     130             :  *  Most of the operations are dummies.
     131             :  */
     132             : 
     133             : const struct consw dummy_con = {
     134             :         .owner =                THIS_MODULE,
     135             :         .con_startup =  dummycon_startup,
     136             :         .con_init =             dummycon_init,
     137             :         .con_deinit =   dummycon_deinit,
     138             :         .con_clear =    dummycon_clear,
     139             :         .con_putc =             dummycon_putc,
     140             :         .con_putcs =    dummycon_putcs,
     141             :         .con_cursor =   dummycon_cursor,
     142             :         .con_scroll =   dummycon_scroll,
     143             :         .con_switch =   dummycon_switch,
     144             :         .con_blank =    dummycon_blank,
     145             : };
     146             : EXPORT_SYMBOL_GPL(dummy_con);