1 files changed, 56 insertions, 0 deletions
diff --git a/grub-core/kern/i386/pit.c b/grub-core/kern/i386/pit.c
new file mode 100644
index 0000000..82a17d3
--- /dev/null
+++ b/grub-core/kern/i386/pit.c
@@ -0,0 +1,56 @@
+/*
+ *  GRUB  --  GRand Unified Bootloader
+ *  Copyright (C) 2008  Free Software Foundation, Inc.
+ *
+ *  GRUB is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  GRUB is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <grub/types.h>
+#include <grub/i386/io.h>
+#include <grub/i386/pit.h>
+
+#define TIMER2_REG_CONTROL	0x42
+#define TIMER_REG_COMMAND	0x43
+#define TIMER2_REG_LATCH	0x61
+
+#define TIMER2_SELECT		0x80
+#define TIMER_ENABLE_LSB	0x20
+#define TIMER_ENABLE_MSB	0x10
+#define TIMER2_LATCH		0x20
+#define TIMER2_SPEAKER		0x02
+#define TIMER2_GATE		0x01
+
+void
+grub_pit_wait (grub_uint16_t tics)
+{
+  /* Disable timer2 gate and speaker.  */
+  grub_outb (grub_inb (TIMER2_REG_LATCH) & ~ (TIMER2_SPEAKER | TIMER2_GATE),
+             TIMER2_REG_LATCH);
+
+  /* Set tics.  */
+  grub_outb (TIMER2_SELECT | TIMER_ENABLE_LSB | TIMER_ENABLE_MSB, TIMER_REG_COMMAND);
+  grub_outb (tics & 0xff, TIMER2_REG_CONTROL);
+  grub_outb (tics >> 8, TIMER2_REG_CONTROL);
+
+  /* Enable timer2 gate, keep speaker disabled.  */
+  grub_outb ((grub_inb (TIMER2_REG_LATCH) & ~ TIMER2_SPEAKER) | TIMER2_GATE,
+             TIMER2_REG_LATCH);
+
+  /* Wait.  */
+  while ((grub_inb (TIMER2_REG_LATCH) & TIMER2_LATCH) == 0x00);
+
+  /* Disable timer2 gate and speaker.  */
+  grub_outb (grub_inb (TIMER2_REG_LATCH) & ~ (TIMER2_SPEAKER | TIMER2_GATE),
+             TIMER2_REG_LATCH);
+}