diff options
Diffstat (limited to 'arch/tile/kernel/vdso/vgettimeofday.c')
-rw-r--r-- | arch/tile/kernel/vdso/vgettimeofday.c | 107 |
1 files changed, 107 insertions, 0 deletions
diff --git a/arch/tile/kernel/vdso/vgettimeofday.c b/arch/tile/kernel/vdso/vgettimeofday.c new file mode 100644 index 000000000000..51ec8e46f5f9 --- /dev/null +++ b/arch/tile/kernel/vdso/vgettimeofday.c @@ -0,0 +1,107 @@ +/* + * Copyright 2012 Tilera Corporation. All Rights Reserved. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation, version 2. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or + * NON INFRINGEMENT. See the GNU General Public License for + * more details. + */ + +#define VDSO_BUILD /* avoid some shift warnings for -m32 in <asm/page.h> */ +#include <linux/time.h> +#include <asm/timex.h> +#include <asm/vdso.h> + +#if CHIP_HAS_SPLIT_CYCLE() +static inline cycles_t get_cycles_inline(void) +{ + unsigned int high = __insn_mfspr(SPR_CYCLE_HIGH); + unsigned int low = __insn_mfspr(SPR_CYCLE_LOW); + unsigned int high2 = __insn_mfspr(SPR_CYCLE_HIGH); + + while (unlikely(high != high2)) { + low = __insn_mfspr(SPR_CYCLE_LOW); + high = high2; + high2 = __insn_mfspr(SPR_CYCLE_HIGH); + } + + return (((cycles_t)high) << 32) | low; +} +#define get_cycles get_cycles_inline +#endif + +/* + * Find out the vDSO data page address in the process address space. + */ +inline unsigned long get_datapage(void) +{ + unsigned long ret; + + /* vdso data page located in the 2nd vDSO page. */ + asm volatile ("lnk %0" : "=r"(ret)); + ret &= ~(PAGE_SIZE - 1); + ret += PAGE_SIZE; + + return ret; +} + +int __vdso_gettimeofday(struct timeval *tv, struct timezone *tz) +{ + cycles_t cycles; + unsigned long count, sec, ns; + volatile struct vdso_data *vdso_data; + + vdso_data = (struct vdso_data *)get_datapage(); + /* The use of the timezone is obsolete, normally tz is NULL. */ + if (unlikely(tz != NULL)) { + while (1) { + /* Spin until the update finish. */ + count = vdso_data->tz_update_count; + if (count & 1) + continue; + + tz->tz_minuteswest = vdso_data->tz_minuteswest; + tz->tz_dsttime = vdso_data->tz_dsttime; + + /* Check whether updated, read again if so. */ + if (count == vdso_data->tz_update_count) + break; + } + } + + if (unlikely(tv == NULL)) + return 0; + + while (1) { + /* Spin until the update finish. */ + count = vdso_data->tb_update_count; + if (count & 1) + continue; + + cycles = (get_cycles() - vdso_data->xtime_tod_stamp); + ns = (cycles * vdso_data->mult) >> vdso_data->shift; + sec = vdso_data->xtime_clock_sec; + ns += vdso_data->xtime_clock_nsec; + if (ns >= NSEC_PER_SEC) { + ns -= NSEC_PER_SEC; + sec += 1; + } + + /* Check whether updated, read again if so. */ + if (count == vdso_data->tb_update_count) + break; + } + + tv->tv_sec = sec; + tv->tv_usec = ns / 1000; + + return 0; +} + +int gettimeofday(struct timeval *tv, struct timezone *tz) + __attribute__((weak, alias("__vdso_gettimeofday"))); |