[OpenBIOS] [PATCH] Add tbu@ and tbl@ words

[John Arbuckle]

The PowerPC timebase register is made available to forth using
the tbu@ and tbl@ words. The tbu@ word pushes the upper 32 bits
of this register. The tbl@ word pushes the lower 32 bits of
this register.

Signed-off-by: John Arbuckle 
---
 arch/ppc/qemu/init.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/arch/ppc/qemu/init.c b/arch/ppc/qemu/init.c
index 5ce080c..d12084c 100644
--- a/arch/ppc/qemu/init.c
+++ b/arch/ppc/qemu/init.c
@@ -751,6 +751,22 @@ static void adler32(void)
     RET(s2 << 16 | s1);
 }

+/* reads the upper timebase register ( -- tbu ) */
+static void get_tbu(void)
+{
+    int time;
+    asm volatile("mftbu %0" : "=r"(time)); // load from TBU register
+    PUSH(time);
+}
+
+/* reads the lower timebase register ( -- tbl ) */
+static void get_tbl(void)
+{
+    int time;
+    asm volatile("mftb %0" : "=r"(time)); // load from TBL register
+    PUSH(time);
+}
+
 void
 arch_of_init(void)
 {
@@ -1022,4 +1038,8 @@ arch_of_init(void)

bind_func("platform-boot", boot);
     bind_func("(arch-go)", arch_go);
+    
+    /* Makes the timebase register accessible from forth */
+    bind_func("tbu@", get_tbu);
+    bind_func("tbl@", get_tbl);
 }