vt: add cursor blink interval escape sequence

Add an escape sequence to specify the current console's cursor blink
interval. The interval is specified as a number of milliseconds until
the next cursor display state toggle, from 50 to 65535. /proc/loadavg
did not show a difference with a one msec interval, but the lower
bound is set to 50 msecs since slower hardware wasn't tested.

Store the interval in the vc_data structure for later access by fbcon,
initializing the value to fbcon's current hardcoded value of 200 msecs.

Signed-off-by: Scot Doyle <lkml14@scotdoyle.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2 files changed, 10 insertions, 0 deletions

diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index 4a24eb2b0ede..b075489f314e 100644
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -135,6 +135,7 @@ const struct consw *conswitchp;
  */
 #define DEFAULT_BELL_PITCH      750
 #define DEFAULT_BELL_DURATION   (HZ/8)
+#define DEFAULT_CURSOR_BLINK_MS 200
 
 struct vc vc_cons [MAX_NR_CONSOLES];
 
@@ -1590,6 +1591,13 @@ static void setterm_command(struct vc_data *vc)
                 case 15: /* activate the previous console */
                         set_console(last_console);
                         break;
+                case 16: /* set cursor blink duration in msec */
+                        if (vc->vc_npar >= 1 && vc->vc_par[1] >= 50 &&
+                                        vc->vc_par[1] <= USHRT_MAX)
+                                vc->vc_cur_blink_ms = vc->vc_par[1];
+                        else
+                                vc->vc_cur_blink_ms = DEFAULT_CURSOR_BLINK_MS;
+                        break;
         }
 }
 
@@ -1717,6 +1725,7 @@ static void reset_terminal(struct vc_data *vc, int do_clear)
 
         vc->vc_bell_pitch = DEFAULT_BELL_PITCH;
         vc->vc_bell_duration = DEFAULT_BELL_DURATION;
+        vc->vc_cur_blink_ms = DEFAULT_CURSOR_BLINK_MS;
 
         gotoxy(vc, 0, 0);
         save_cur(vc);
diff --git a/include/linux/console_struct.h b/include/linux/console_struct.h
index e859c98d1767..e329ee2667e1 100644
--- a/include/linux/console_struct.h
+++ b/include/linux/console_struct.h
@@ -104,6 +104,7 @@ struct vc_data {
         unsigned int    vc_resize_user;         /* resize request from user */
         unsigned int    vc_bell_pitch;          /* Console bell pitch */
         unsigned int    vc_bell_duration;       /* Console bell duration */
+        unsigned short  vc_cur_blink_ms;        /* Cursor blink duration */
         struct vc_data **vc_display_fg;         /* [!] Ptr to var holding fg console for this display */
         struct uni_pagedir *vc_uni_pagedir;
         struct uni_pagedir **vc_uni_pagedir_loc; /* [!] Location of uni_pagedir variable for this console */