diff options
Diffstat (limited to 'arch/xtensa/include/asm/delay.h')
| -rw-r--r-- | arch/xtensa/include/asm/delay.h | 52 |
1 files changed, 43 insertions, 9 deletions
diff --git a/arch/xtensa/include/asm/delay.h b/arch/xtensa/include/asm/delay.h index 3899610c1dff..24304b39a5c7 100644 --- a/arch/xtensa/include/asm/delay.h +++ b/arch/xtensa/include/asm/delay.h @@ -19,23 +19,57 @@ extern unsigned long loops_per_jiffy; static inline void __delay(unsigned long loops) { - /* 2 cycles per loop. */ - __asm__ __volatile__ ("1: addi %0, %0, -2; bgeui %0, 2, 1b" - : "=r" (loops) : "0" (loops)); + if (__builtin_constant_p(loops) && loops < 2) + __asm__ __volatile__ ("nop"); + else if (loops >= 2) + /* 2 cycles per loop. */ + __asm__ __volatile__ ("1: addi %0, %0, -2; bgeui %0, 2, 1b" + : "+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); +void __bad_ndelay(void); -static __inline__ void udelay (unsigned long usecs) +#define __MAX_UDELAY 30000 +#define __MAX_NDELAY 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); +} + +static inline void __ndelay(unsigned long nsec) +{ + /* + * Inner shift makes sure multiplication doesn't overflow + * for legitimate nsec values + */ + unsigned long cycles = (nsec * (ccount_freq >> 15)) >> 15; + __delay(cycles); +} + +#define ndelay(n) ndelay(n) + +static inline void ndelay(unsigned long nsec) +{ + if (__builtin_constant_p(nsec) && nsec >= __MAX_NDELAY) + __bad_ndelay(); + else + __ndelay(nsec); } #endif |