forked from Minki/linux
xtensa: clean up udelay
Replace division with shift, use ccount_freq instead of loops_per_jiffy. Introduce __MAX_UDELAY and (undefined) __bad_udelay, break build for too big udelay constants. Remove irrelevant comment, clean up code style. Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
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@ -27,18 +27,27 @@ static inline void __delay(unsigned long loops)
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: "+r" (loops));
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}
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/* For SMP/NUMA systems, change boot_cpu_data to something like
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* local_cpu_data->... where local_cpu_data points to the current
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* cpu. */
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/* Undefined function to get compile-time error */
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void __bad_udelay(void);
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static __inline__ void udelay (unsigned long usecs)
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#define __MAX_UDELAY 30000
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static inline void __udelay(unsigned long usecs)
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{
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unsigned long start = get_ccount();
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unsigned long cycles = usecs * (loops_per_jiffy / (1000000UL / HZ));
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unsigned long cycles = (usecs * (ccount_freq >> 15)) >> 5;
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/* Note: all variables are unsigned (can wrap around)! */
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while (((unsigned long)get_ccount()) - start < cycles)
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;
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cpu_relax();
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}
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static inline void udelay(unsigned long usec)
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{
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if (__builtin_constant_p(usec) && usec >= __MAX_UDELAY)
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__bad_udelay();
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else
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__udelay(usec);
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}
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#endif
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