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Subject[PATCH v7 2/3] console: Add callback to flush scrollback buffer to consw struct
Date
This new callback is in preparation for persistent scrollback buffer
support for VGA consoles.
With a single scrollback buffer for all consoles, we could flush the
buffer just by invocating consw->con_switch(). But when each VGA console
has its own scrollback buffer, we need a new callback to tell the
video console driver which buffer to flush.

Signed-off-by: Manuel Schölling <manuel.schoelling@gmx.de>
Reviewed-by: Andrey Utkin <andrey_utkin@fastmail.com>
Tested-by: Andrey Utkin <andrey_utkin@fastmail.com>
Tested-by: Adam Borowski <kilobyte@angband.pl>

---
drivers/tty/vt/vt.c | 9 +++++++++
drivers/video/console/vgacon.c | 24 +++++++++++++++++++++++-
include/linux/console.h | 4 ++++
3 files changed, 36 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index 4c10a9d..9d3ce50 100644
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -625,6 +625,14 @@ static void save_screen(struct vc_data *vc)
vc->vc_sw->con_save_screen(vc);
}

+static void flush_scrollback(struct vc_data *vc)
+{
+ WARN_CONSOLE_UNLOCKED();
+
+ if (vc->vc_sw->con_flush_scrollback)
+ vc->vc_sw->con_flush_scrollback(vc);
+}
+
/*
* Redrawing of screen
*/
@@ -1171,6 +1179,7 @@ static void csi_J(struct vc_data *vc, int vpar)
case 3: /* erase scroll-back buffer (and whole display) */
scr_memsetw(vc->vc_screenbuf, vc->vc_video_erase_char,
vc->vc_screenbuf_size);
+ flush_scrollback(vc);
set_origin(vc);
if (con_is_visible(vc))
update_screen(vc);
diff --git a/drivers/video/console/vgacon.c b/drivers/video/console/vgacon.c
index 48b9764..9a7c2bb 100644
--- a/drivers/video/console/vgacon.c
+++ b/drivers/video/console/vgacon.c
@@ -173,6 +173,16 @@ static struct vgacon_scrollback_info {
int restore;
} vgacon_scrollback;

+static void vgacon_scrollback_reset(size_t reset_size)
+{
+ if (vgacon_scrollback.data && reset_size > 0)
+ memset(vgacon_scrollback.data, 0, reset_size);
+
+ vgacon_scrollback.cnt = 0;
+ vgacon_scrollback.tail = 0;
+ vgacon_scrollback.cur = 0;
+}
+
static void vgacon_scrollback_init(int pitch)
{
int rows = CONFIG_VGACON_SOFT_SCROLLBACK_SIZE * 1024/pitch;
@@ -305,6 +315,14 @@ static void vgacon_scrolldelta(struct vc_data *c, int lines)
} else
vgacon_cursor(c, CM_MOVE);
}
+
+static void vgacon_flush_scrollback(struct vc_data *c)
+{
+ size_t size = CONFIG_VGACON_SOFT_SCROLLBACK_SIZE * 1024;
+
+ if (c->vc_num == fg_console)
+ vgacon_scrollback_reset(size);
+}
#else
#define vgacon_scrollback_startup(...) do { } while (0)
#define vgacon_scrollback_init(...) do { } while (0)
@@ -322,6 +340,10 @@ static void vgacon_scrolldelta(struct vc_data *c, int lines)
vga_vram_size);
vga_set_mem_top(c);
}
+
+static void vgacon_flush_scrollback(struct vc_data *c)
+{
+}
#endif /* CONFIG_VGACON_SOFT_SCROLLBACK */

static const char *vgacon_startup(void)
@@ -1329,7 +1351,6 @@ static bool vgacon_scroll(struct vc_data *c, unsigned int t, unsigned int b,
return true;
}

-
/*
* The console `switch' structure for the VGA based console
*/
@@ -1362,6 +1383,7 @@ const struct consw vga_con = {
.con_save_screen = vgacon_save_screen,
.con_build_attr = vgacon_build_attr,
.con_invert_region = vgacon_invert_region,
+ .con_flush_scrollback = vgacon_flush_scrollback,
};
EXPORT_SYMBOL(vga_con);

diff --git a/include/linux/console.h b/include/linux/console.h
index 9c26c66..5949d18 100644
--- a/include/linux/console.h
+++ b/include/linux/console.h
@@ -73,6 +73,10 @@ struct consw {
u16 *(*con_screen_pos)(struct vc_data *, int);
unsigned long (*con_getxy)(struct vc_data *, unsigned long, int *, int *);
/*
+ * Flush the video console driver's scrollback buffer
+ */
+ void (*con_flush_scrollback)(struct vc_data *);
+ /*
* Prepare the console for the debugger. This includes, but is not
* limited to, unblanking the console, loading an appropriate
* palette, and allowing debugger generated output.
--
2.1.4
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