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/*
* Copyright (C) 2015 Imagination Technologies
* Author: Alex Smith <alex.smith@imgtec.com>
*
* 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; either version 2 of the License, or (at your
* option) any later version.
*/
#include "vdso.h"
#include <linux/compiler.h>
#include <linux/irqchip/mips-gic.h>
#include <linux/time.h>
#include <asm/clocksource.h>
#include <asm/io.h>
#include <asm/mips-cm.h>
#include <asm/unistd.h>
#include <asm/vdso.h>
static __always_inline long clock_gettime_fallback(clockid_t _clkid,
struct timespec *_ts)
{
register struct timespec *ts asm("a1") = _ts;
register clockid_t clkid asm("a0") = _clkid;
register long ret asm("v0");
register long nr asm("v0") = __NR_clock_gettime;
register long error asm("a3");
asm volatile(
" syscall\n"
: "=r" (ret), "=r" (error)
: "r" (clkid), "r" (ts), "r" (nr)
: "memory");
return error ? -ret : ret;
}
static __always_inline int do_realtime_coarse(struct timespec *ts,
const union mips_vdso_data *data)
{
u32 start_seq;
do {
start_seq = vdso_data_read_begin(data);
ts->tv_sec = data->xtime_sec;
ts->tv_nsec = data->xtime_nsec >> data->cs_shift;
} while (vdso_data_read_retry(data, start_seq));
return 0;
}
static __always_inline int do_monotonic_coarse(struct timespec *ts,
const union mips_vdso_data *data)
{
u32 start_seq;
u64 to_mono_sec;
u64 to_mono_nsec;
do {
start_seq = vdso_data_read_begin(data);
ts->tv_sec = data->xtime_sec;
ts->tv_nsec = data->xtime_nsec >> data->cs_shift;
to_mono_sec = data->wall_to_mono_sec;
to_mono_nsec = data->wall_to_mono_nsec;
} while (vdso_data_read_retry(data, start_seq));
ts->tv_sec += to_mono_sec;
timespec_add_ns(ts, to_mono_nsec);
return 0;
}
#ifdef CONFIG_CSRC_R4K
static __always_inline u64 read_r4k_count(void)
{
unsigned int count;
__asm__ __volatile__(
" .set push\n"
" .set mips32r2\n"
" rdhwr %0, $2\n"
" .set pop\n"
: "=r" (count));
return count;
}
#endif
#ifdef CONFIG_CLKSRC_MIPS_GIC
static __always_inline u64 read_gic_count(const union mips_vdso_data *data)
{
void __iomem *gic = get_gic(data);
u32 hi, hi2, lo;
do {
hi = __raw_readl(gic + GIC_UMV_SH_COUNTER_63_32_OFS);
lo = __raw_readl(gic + GIC_UMV_SH_COUNTER_31_00_OFS);
hi2 = __raw_readl(gic + GIC_UMV_SH_COUNTER_63_32_OFS);
} while (hi2 != hi);
return (((u64)hi) << 32) + lo;
}
#endif
static __always_inline u64 get_ns(const union mips_vdso_data *data)
{
u64 cycle_now, delta, nsec;
switch (data->clock_mode) {
#ifdef CONFIG_CSRC_R4K
case VDSO_CLOCK_R4K:
cycle_now = read_r4k_count();
break;
#endif
#ifdef CONFIG_CLKSRC_MIPS_GIC
case VDSO_CLOCK_GIC:
cycle_now = read_gic_count(data);
break;
#endif
default:
return 0;
}
delta = (cycle_now - data->cs_cycle_last) & data->cs_mask;
nsec = (delta * data->cs_mult) + data->xtime_nsec;
nsec >>= data->cs_shift;
return nsec;
}
static __always_inline int do_realtime(struct timespec *ts,
const union mips_vdso_data *data)
{
u32 start_seq;
u64 ns;
do {
start_seq = vdso_data_read_begin(data);
if (data->clock_mode == VDSO_CLOCK_NONE)
return -ENOSYS;
ts->tv_sec = data->xtime_sec;
ns = get_ns(data);
} while (vdso_data_read_retry(data, start_seq));
ts->tv_nsec = 0;
timespec_add_ns(ts, ns);
return 0;
}
static __always_inline int do_monotonic(struct timespec *ts,
const union mips_vdso_data *data)
{
u32 start_seq;
u64 ns;
u64 to_mono_sec;
u64 to_mono_nsec;
do {
start_seq = vdso_data_read_begin(data);
if (data->clock_mode == VDSO_CLOCK_NONE)
return -ENOSYS;
ts->tv_sec = data->xtime_sec;
ns = get_ns(data);
to_mono_sec = data->wall_to_mono_sec;
to_mono_nsec = data->wall_to_mono_nsec;
} while (vdso_data_read_retry(data, start_seq));
ts->tv_sec += to_mono_sec;
ts->tv_nsec = 0;
timespec_add_ns(ts, ns + to_mono_nsec);
return 0;
}
#ifdef CONFIG_MIPS_CLOCK_VSYSCALL
/*
* This is behind the ifdef so that we don't provide the symbol when there's no
* possibility of there being a usable clocksource, because there's nothing we
* can do without it. When libc fails the symbol lookup it should fall back on
* the standard syscall path.
*/
int __vdso_gettimeofday(struct timeval *tv, struct timezone *tz)
{
const union mips_vdso_data *data = get_vdso_data();
struct timespec ts;
int ret;
ret = do_realtime(&ts, data);
if (ret)
return ret;
if (tv) {
tv->tv_sec = ts.tv_sec;
tv->tv_usec = ts.tv_nsec / 1000;
}
if (tz) {
tz->tz_minuteswest = data->tz_minuteswest;
tz->tz_dsttime = data->tz_dsttime;
}
return 0;
}
#endif /* CONFIG_CLKSRC_MIPS_GIC */
int __vdso_clock_gettime(clockid_t clkid, struct timespec *ts)
{
const union mips_vdso_data *data = get_vdso_data();
int ret = -1;
switch (clkid) {
case CLOCK_REALTIME_COARSE:
ret = do_realtime_coarse(ts, data);
break;
case CLOCK_MONOTONIC_COARSE:
ret = do_monotonic_coarse(ts, data);
break;
case CLOCK_REALTIME:
ret = do_realtime(ts, data);
break;
case CLOCK_MONOTONIC:
ret = do_monotonic(ts, data);
break;
default:
break;
}
if (ret)
ret = clock_gettime_fallback(clkid, ts);
return ret;
}
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