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authorAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
committerAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
commit57f0f512b273f60d52568b8c6b77e17f5636edc0 (patch)
tree5e910f0e82173f4ef4f51111366a3f1299037a7b /arch/m68k/include/asm/delay.h
Initial import
Diffstat (limited to 'arch/m68k/include/asm/delay.h')
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diff --git a/arch/m68k/include/asm/delay.h b/arch/m68k/include/asm/delay.h
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+++ b/arch/m68k/include/asm/delay.h
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+#ifndef _M68K_DELAY_H
+#define _M68K_DELAY_H
+
+#include <asm/param.h>
+
+/*
+ * Copyright (C) 1994 Hamish Macdonald
+ * Copyright (C) 2004 Greg Ungerer <gerg@uclinux.com>
+ *
+ * Delay routines, using a pre-computed "loops_per_jiffy" value.
+ */
+
+#if defined(CONFIG_COLDFIRE)
+/*
+ * The ColdFire runs the delay 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 arbitrary 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.
+ */
+#define DELAY_ALIGN ".balignw 4, 0x4a8e\n\t"
+#else
+/*
+ * No instruction alignment required for other m68k types.
+ */
+#define DELAY_ALIGN
+#endif
+
+static inline void __delay(unsigned long loops)
+{
+ __asm__ __volatile__ (
+ DELAY_ALIGN
+ "1: subql #1,%0\n\t"
+ "jcc 1b"
+ : "=d" (loops)
+ : "0" (loops));
+}
+
+extern void __bad_udelay(void);
+
+
+#ifdef CONFIG_CPU_HAS_NO_MULDIV64
+/*
+ * The simpler m68k and ColdFire processors do not have a 32*32->64
+ * multiply instruction. So we need to handle them a little differently.
+ * We use a bit of shifting and a single 32*32->32 multiply to get close.
+ * This is a macro so that the const version can factor out the first
+ * multiply and shift.
+ */
+#define HZSCALE (268435456 / (1000000 / HZ))
+
+#define __const_udelay(u) \
+ __delay(((((u) * HZSCALE) >> 11) * (loops_per_jiffy >> 11)) >> 6)
+
+#else
+
+static inline void __xdelay(unsigned long xloops)
+{
+ unsigned long tmp;
+
+ __asm__ ("mulul %2,%0:%1"
+ : "=d" (xloops), "=d" (tmp)
+ : "d" (xloops), "1" (loops_per_jiffy));
+ __delay(xloops * HZ);
+}
+
+/*
+ * The definition of __const_udelay is specifically made a macro so that
+ * the const factor (4295 = 2**32 / 1000000) can be optimized out when
+ * the delay is a const.
+ */
+#define __const_udelay(n) (__xdelay((n) * 4295))
+
+#endif
+
+static inline void __udelay(unsigned long usecs)
+{
+ __const_udelay(usecs);
+}
+
+/*
+ * Use only for very small delays ( < 1 msec). Should probably use a
+ * lookup table, really, as the multiplications take much too long with
+ * short delays. This is a "reasonable" implementation, though (and the
+ * first constant multiplications gets optimized away if the delay is
+ * a constant)
+ */
+#define udelay(n) (__builtin_constant_p(n) ? \
+ ((n) > 20000 ? __bad_udelay() : __const_udelay(n)) : __udelay(n))
+
+/*
+ * nanosecond delay:
+ *
+ * ((((HZSCALE) >> 11) * (loops_per_jiffy >> 11)) >> 6) is the number of loops
+ * per microsecond
+ *
+ * 1000 / ((((HZSCALE) >> 11) * (loops_per_jiffy >> 11)) >> 6) is the number of
+ * nanoseconds per loop
+ *
+ * So n / ( 1000 / ((((HZSCALE) >> 11) * (loops_per_jiffy >> 11)) >> 6) ) would
+ * be the number of loops for n nanoseconds
+ */
+
+/*
+ * The simpler m68k and ColdFire processors do not have a 32*32->64
+ * multiply instruction. So we need to handle them a little differently.
+ * We use a bit of shifting and a single 32*32->32 multiply to get close.
+ * This is a macro so that the const version can factor out the first
+ * multiply and shift.
+ */
+#define HZSCALE (268435456 / (1000000 / HZ))
+
+#define ndelay(n) __delay(DIV_ROUND_UP((n) * ((((HZSCALE) >> 11) * (loops_per_jiffy >> 11)) >> 6), 1000));
+
+#endif /* defined(_M68K_DELAY_H) */