arch/nds32/kernel/vdso/gettimeofday.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 // Copyright (C) 2005-2017 Andes Technology Corporation
   3
   4 #include <linux/compiler.h>
   5 #include <linux/hrtimer.h>
   6 #include <linux/time.h>
   7 #include <asm/io.h>
   8 #include <asm/barrier.h>
   9 #include <asm/bug.h>
  10 #include <asm/page.h>
  11 #include <asm/unistd.h>
  12 #include <asm/vdso_datapage.h>
  13 #include <asm/vdso_timer_info.h>
  14 #include <asm/asm-offsets.h>
  15
  16 #define X(x) #x
  17 #define Y(x) X(x)
  18
  19 extern struct vdso_data *__get_datapage(void);
  20 extern struct vdso_data *__get_timerpage(void);
  21
  22 static notrace unsigned int __vdso_read_begin(const struct vdso_data *vdata)
  23 {
  24         u32 seq;
  25 repeat:
  26         seq = READ_ONCE(vdata->seq_count);
  27         if (seq & 1) {
  28                 cpu_relax();
  29                 goto repeat;
  30         }
  31         return seq;
  32 }
  33
  34 static notrace unsigned int vdso_read_begin(const struct vdso_data *vdata)
  35 {
  36         unsigned int seq;
  37
  38         seq = __vdso_read_begin(vdata);
  39
  40         smp_rmb();              /* Pairs with smp_wmb in vdso_write_end */
  41         return seq;
  42 }
  43
  44 static notrace int vdso_read_retry(const struct vdso_data *vdata, u32 start)
  45 {
  46         smp_rmb();              /* Pairs with smp_wmb in vdso_write_begin */
  47         return vdata->seq_count != start;
  48 }
  49
  50 static notrace long clock_gettime_fallback(clockid_t _clkid,
  51                                            struct __kernel_old_timespec *_ts)
  52 {
  53         register struct __kernel_old_timespec *ts asm("$r1") = _ts;
  54         register clockid_t clkid asm("$r0") = _clkid;
  55         register long ret asm("$r0");
  56
  57         asm volatile ("movi     $r15, %3\n"
  58                       "syscall  0x0\n"
  59                       :"=r" (ret)
  60                       :"r"(clkid), "r"(ts), "i"(__NR_clock_gettime)
  61                       :"$r15", "memory");
  62
  63         return ret;
  64 }
  65
  66 static notrace int do_realtime_coarse(struct __kernel_old_timespec *ts,
  67                                       struct vdso_data *vdata)
  68 {
  69         u32 seq;
  70
  71         do {
  72                 seq = vdso_read_begin(vdata);
  73
  74                 ts->tv_sec = vdata->xtime_coarse_sec;
  75                 ts->tv_nsec = vdata->xtime_coarse_nsec;
  76
  77         } while (vdso_read_retry(vdata, seq));
  78         return 0;
  79 }
  80
  81 static notrace int do_monotonic_coarse(struct __kernel_old_timespec *ts,
  82                                        struct vdso_data *vdata)
  83 {
  84         u32 seq;
  85         u64 ns;
  86
  87         do {
  88                 seq = vdso_read_begin(vdata);
  89
  90                 ts->tv_sec = vdata->xtime_coarse_sec + vdata->wtm_clock_sec;
  91                 ns = vdata->xtime_coarse_nsec + vdata->wtm_clock_nsec;
  92
  93         } while (vdso_read_retry(vdata, seq));
  94
  95         ts->tv_sec += __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns);
  96         ts->tv_nsec = ns;
  97
  98         return 0;
  99 }
 100
 101 static notrace inline u64 vgetsns(struct vdso_data *vdso)
 102 {
 103         u32 cycle_now;
 104         u32 cycle_delta;
 105         u32 *timer_cycle_base;
 106
 107         timer_cycle_base =
 108             (u32 *) ((char *)__get_timerpage() + vdso->cycle_count_offset);
 109         cycle_now = readl_relaxed(timer_cycle_base);
 110         if (true == vdso->cycle_count_down)
 111                 cycle_now = ~(*timer_cycle_base);
 112         cycle_delta = cycle_now - (u32) vdso->cs_cycle_last;
 113         return ((u64) cycle_delta & vdso->cs_mask) * vdso->cs_mult;
 114 }
 115
 116 static notrace int do_realtime(struct __kernel_old_timespec *ts, struct vdso_data *vdata)
 117 {
 118         unsigned count;
 119         u64 ns;
 120         do {
 121                 count = vdso_read_begin(vdata);
 122                 ts->tv_sec = vdata->xtime_clock_sec;
 123                 ns = vdata->xtime_clock_nsec;
 124                 ns += vgetsns(vdata);
 125                 ns >>= vdata->cs_shift;
 126         } while (vdso_read_retry(vdata, count));
 127
 128         ts->tv_sec += __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns);
 129         ts->tv_nsec = ns;
 130
 131         return 0;
 132 }
 133
 134 static notrace int do_monotonic(struct __kernel_old_timespec *ts, struct vdso_data *vdata)
 135 {
 136         u64 ns;
 137         u32 seq;
 138
 139         do {
 140                 seq = vdso_read_begin(vdata);
 141
 142                 ts->tv_sec = vdata->xtime_clock_sec;
 143                 ns = vdata->xtime_clock_nsec;
 144                 ns += vgetsns(vdata);
 145                 ns >>= vdata->cs_shift;
 146
 147                 ts->tv_sec += vdata->wtm_clock_sec;
 148                 ns += vdata->wtm_clock_nsec;
 149
 150         } while (vdso_read_retry(vdata, seq));
 151
 152         ts->tv_sec += __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns);
 153         ts->tv_nsec = ns;
 154
 155         return 0;
 156 }
 157
 158 notrace int __vdso_clock_gettime(clockid_t clkid, struct __kernel_old_timespec *ts)
 159 {
 160         struct vdso_data *vdata;
 161         int ret = -1;
 162
 163         vdata = __get_datapage();
 164         if (vdata->cycle_count_offset == EMPTY_REG_OFFSET)
 165                 return clock_gettime_fallback(clkid, ts);
 166
 167         switch (clkid) {
 168         case CLOCK_REALTIME_COARSE:
 169                 ret = do_realtime_coarse(ts, vdata);
 170                 break;
 171         case CLOCK_MONOTONIC_COARSE:
 172                 ret = do_monotonic_coarse(ts, vdata);
 173                 break;
 174         case CLOCK_REALTIME:
 175                 ret = do_realtime(ts, vdata);
 176                 break;
 177         case CLOCK_MONOTONIC:
 178                 ret = do_monotonic(ts, vdata);
 179                 break;
 180         default:
 181                 break;
 182         }
 183
 184         if (ret)
 185                 ret = clock_gettime_fallback(clkid, ts);
 186
 187         return ret;
 188 }
 189
 190 static notrace int clock_getres_fallback(clockid_t _clk_id,
 191                                           struct __kernel_old_timespec *_res)
 192 {
 193         register clockid_t clk_id asm("$r0") = _clk_id;
 194         register struct __kernel_old_timespec *res asm("$r1") = _res;
 195         register int ret asm("$r0");
 196
 197         asm volatile ("movi     $r15, %3\n"
 198                       "syscall  0x0\n"
 199                       :"=r" (ret)
 200                       :"r"(clk_id), "r"(res), "i"(__NR_clock_getres)
 201                       :"$r15", "memory");
 202
 203         return ret;
 204 }
 205
 206 notrace int __vdso_clock_getres(clockid_t clk_id, struct __kernel_old_timespec *res)
 207 {
 208         struct vdso_data *vdata = __get_datapage();
 209
 210         if (res == NULL)
 211                 return 0;
 212         switch (clk_id) {
 213         case CLOCK_REALTIME:
 214         case CLOCK_MONOTONIC:
 215         case CLOCK_MONOTONIC_RAW:
 216                 res->tv_sec = 0;
 217                 res->tv_nsec = vdata->hrtimer_res;
 218                 break;
 219         case CLOCK_REALTIME_COARSE:
 220         case CLOCK_MONOTONIC_COARSE:
 221                 res->tv_sec = 0;
 222                 res->tv_nsec = CLOCK_COARSE_RES;
 223                 break;
 224         default:
 225                 return clock_getres_fallback(clk_id, res);
 226         }
 227         return 0;
 228 }
 229
 230 static notrace inline int gettimeofday_fallback(struct __kernel_old_timeval *_tv,
 231                                                 struct timezone *_tz)
 232 {
 233         register struct __kernel_old_timeval *tv asm("$r0") = _tv;
 234         register struct timezone *tz asm("$r1") = _tz;
 235         register int ret asm("$r0");
 236
 237         asm volatile ("movi     $r15, %3\n"
 238                       "syscall  0x0\n"
 239                       :"=r" (ret)
 240                       :"r"(tv), "r"(tz), "i"(__NR_gettimeofday)
 241                       :"$r15", "memory");
 242
 243         return ret;
 244 }
 245
 246 notrace int __vdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
 247 {
 248         struct __kernel_old_timespec ts;
 249         struct vdso_data *vdata;
 250         int ret;
 251
 252         vdata = __get_datapage();
 253
 254         if (vdata->cycle_count_offset == EMPTY_REG_OFFSET)
 255                 return gettimeofday_fallback(tv, tz);
 256
 257         ret = do_realtime(&ts, vdata);
 258
 259         if (tv) {
 260                 tv->tv_sec = ts.tv_sec;
 261                 tv->tv_usec = ts.tv_nsec / 1000;
 262         }
 263         if (tz) {
 264                 tz->tz_minuteswest = vdata->tz_minuteswest;
 265                 tz->tz_dsttime = vdata->tz_dsttime;
 266         }
 267
 268         return ret;
 269 }