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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /include/asm-m68knommu/delay.h
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Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'include/asm-m68knommu/delay.h')
-rw-r--r--include/asm-m68knommu/delay.h76
1 files changed, 76 insertions, 0 deletions
diff --git a/include/asm-m68knommu/delay.h b/include/asm-m68knommu/delay.h
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+++ b/include/asm-m68knommu/delay.h
@@ -0,0 +1,76 @@
+#ifndef _M68KNOMMU_DELAY_H
+#define _M68KNOMMU_DELAY_H
+
+/*
+ * Copyright (C) 1994 Hamish Macdonald
+ * Copyright (C) 2004 Greg Ungerer <gerg@snapgear.com>
+ */
+
+#include <asm/param.h>
+
+extern __inline__ void __delay(unsigned long loops)
+{
+#if defined(CONFIG_COLDFIRE)
+ /* The coldfire runs this loop at significantly different speeds
+ * depending upon long word alignment or not. We'll pad it to
+ * long word alignment which is the faster version.
+ * The 0x4a8e is of course a 'tstl %fp' instruction. This is better
+ * than using a NOP (0x4e71) instruction because it executes in one
+ * cycle not three and doesn't allow for an arbitary delay waiting
+ * for bus cycles to finish. Also fp/a6 isn't likely to cause a
+ * stall waiting for the register to become valid if such is added
+ * to the coldfire at some stage.
+ */
+ __asm__ __volatile__ ( ".balignw 4, 0x4a8e\n\t"
+ "1: subql #1, %0\n\t"
+ "jcc 1b"
+ : "=d" (loops) : "0" (loops));
+#else
+ __asm__ __volatile__ ( "1: subql #1, %0\n\t"
+ "jcc 1b"
+ : "=d" (loops) : "0" (loops));
+#endif
+}
+
+/*
+ * Ideally we use a 32*32->64 multiply to calculate the number of
+ * loop iterations, but the older standard 68k and ColdFire do not
+ * have this instruction. So for them we have a clsoe approximation
+ * loop using 32*32->32 multiplies only. This calculation based on
+ * the ARM version of delay.
+ *
+ * We want to implement:
+ *
+ * loops = (usecs * 0x10c6 * HZ * loops_per_jiffy) / 2^32
+ */
+
+#define HZSCALE (268435456 / (1000000/HZ))
+
+extern unsigned long loops_per_jiffy;
+
+extern __inline__ void _udelay(unsigned long usecs)
+{
+#if defined(CONFIG_M68328) || defined(CONFIG_M68EZ328) || \
+ defined(CONFIG_M68VZ328) || defined(CONFIG_M68360) || \
+ defined(CONFIG_COLDFIRE)
+ __delay((((usecs * HZSCALE) >> 11) * (loops_per_jiffy >> 11)) >> 6);
+#else
+ unsigned long tmp;
+
+ usecs *= 4295; /* 2**32 / 1000000 */
+ __asm__ ("mulul %2,%0:%1"
+ : "=d" (usecs), "=d" (tmp)
+ : "d" (usecs), "1" (loops_per_jiffy*HZ));
+ __delay(usecs);
+#endif
+}
+
+/*
+ * Moved the udelay() function into library code, no longer inlined.
+ * I had to change the algorithm because we are overflowing now on
+ * the faster ColdFire parts. The code is a little biger, so it makes
+ * sense to library it.
+ */
+extern void udelay(unsigned long usecs);
+
+#endif /* defined(_M68KNOMMU_DELAY_H) */
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