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

[BALATON Zoltan]

I've tried to implement it the way I've suggested and came up with the 
patch below, but it does not seem to work. I think this is because the 
arithmetic in get-msec overflows and does not get the right values. Could 
it be it works in SLOF because that runs on 64bit? Or is something needed 
to tell Forth to use 64bit values on PPC32? Any ideas?

Regards,
BALATON Zoltan

diff --git a/arch/ppc/qemu/init.c b/arch/ppc/qemu/init.c
index b0c0cfc..4c8631a 100644
--- a/arch/ppc/qemu/init.c
+++ b/arch/ppc/qemu/init.c
@@ -793,6 +793,20 @@ static void adler32(void)
     RET(s2 << 16 | s1);
 }

+/*
+ * Get time base value from CPU
+ */
+static void tb_fetch(void)
+{
+    unsigned long tbl, tbu;
+
+    do {
+      tbu = mftbu();
+      tbl = mftb();
+    } while (tbu != mftbu());
+    DPUSH(((uint64_t)tbu << 32) | tbl);
+}
+
 void
 arch_of_init(void)
 {
@@ -1062,7 +1076,9 @@ arch_of_init(void)

     /* Implementation of adler32 word (required by OS 9, BootX) */
     bind_func("(adler32)", adler32);
- 
+
+    fword("fixup-tbfreq");
+    bind_func("(tb@)", tb_fetch);
     bind_func("platform-boot", boot);
     bind_func("(arch-go)", arch_go);
 }
diff --git a/arch/ppc/qemu/qemu.fs b/arch/ppc/qemu/qemu.fs
index d683421..1e3e0cb 100644
--- a/arch/ppc/qemu/qemu.fs
+++ b/arch/ppc/qemu/qemu.fs
@@ -139,3 +139,34 @@ variable keyboard-phandle 0 keyboard-phandle !
     3drop 0
   then
 ;
+
+\ -------------------------------------------------------------------------
+\ time base related words
+\ -------------------------------------------------------------------------
+
+1 value tb-frequency
+
+: fixup-tbfreq
+  " /cpus/@0" find-device
+  " timebase-frequency" active-package get-package-property IF
+    2drop
+  ELSE
+    decode-int to tb-frequency 2drop
+  THEN
+  device-end
+;
+
+: tb@ ( -- tbval)
+  " (tb@)" $find if
+    execute
+    20 lshift swap ffffffff and or
+  else
+    2drop 0
+  then
+;
+
+: get-msecs ( -- ms ) tb@ d# 1000 * tb-frequency / ;
+: get-usecs ( -- us ) tb@ d# 1000000 * tb-frequency / ;
+
+: ms ( ms-to-wait -- ) get-msecs + BEGIN get-msecs over >= UNTIL drop ;
+: us  ( us-to-wait -- )  get-usecs +  BEGIN get-usecs over >= UNTIL  drop ;
diff --git a/include/arch/ppc/processor.h b/include/arch/ppc/processor.h
index bb03bb1..5e79ba8 100644
--- a/include/arch/ppc/processor.h
+++ b/include/arch/ppc/processor.h
@@ -462,6 +462,20 @@ static inline void slbmte(unsigned long rs, unsigned long rb)
     asm volatile("slbmte %0,%1 ; isync" :: "r" (rs), "r" (rb) : "memory");
 }

+static inline unsigned long mftb(void)
+{
+    unsigned long val;
+    asm volatile("mftb %0" : "=r" (val));
+    return val;
+}
+
+static inline unsigned long mftbu(void)
+{
+    unsigned long val;
+    asm volatile("mftbu %0" : "=r" (val));
+    return val;
+}
+
 #endif /* !__ASSEMBLER__ */

 #endif   /* _H_PROCESSOR */