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>

diff --git a/arch/xtensa/include/asm/delay.h b/arch/xtensa/include/asm/delay.h
index 742b89f3ca2cf22d535b21441383b97256bf5903..69ba4629bed09025e38de039e7a2d25d73a89a19 100644 (file)
--- a/arch/xtensa/include/asm/delay.h
+++ b/arch/xtensa/include/asm/delay.h
@@ -27,18 +27,27 @@ static inline void __delay(unsigned long loops)
                                : "+r" (loops));
 }
 
-/* For SMP/NUMA systems, change boot_cpu_data to something like
- * local_cpu_data->... where local_cpu_data points to the current
- * cpu. */
+/* Undefined function to get compile-time error */
+void __bad_udelay(void);
 
-static __inline__ void udelay (unsigned long usecs)
+#define __MAX_UDELAY 30000
+
+static inline void __udelay(unsigned long usecs)
 {
        unsigned long start = get_ccount();
-       unsigned long cycles = usecs * (loops_per_jiffy / (1000000UL / HZ));
+       unsigned long cycles = (usecs * (ccount_freq >> 15)) >> 5;
 
        /* Note: all variables are unsigned (can wrap around)! */
        while (((unsigned long)get_ccount()) - start < cycles)
-               ;
+               cpu_relax();
+}
+
+static inline void udelay(unsigned long usec)
+{
+       if (__builtin_constant_p(usec) && usec >= __MAX_UDELAY)
+               __bad_udelay();
+       else
+               __udelay(usec);
 }
 
 #endif