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 timespec *_ts)
  52 {
  53         register struct 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 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 timespec *ts,
  82                                        struct vdso_data *vdata)
  83 {
  84         struct timespec tomono;
  85         u32 seq;
  86
  87         do {
  88                 seq = vdso_read_begin(vdata);
  89
  90                 ts->tv_sec = vdata->xtime_coarse_sec;
  91                 ts->tv_nsec = vdata->xtime_coarse_nsec;
  92
  93                 tomono.tv_sec = vdata->wtm_clock_sec;
  94                 tomono.tv_nsec = vdata->wtm_clock_nsec;
  95
  96         } while (vdso_read_retry(vdata, seq));
  97
  98         ts->tv_sec += tomono.tv_sec;
  99         timespec_add_ns(ts, tomono.tv_nsec);
 100         return 0;
 101 }
 102
 103 static notrace inline u64 vgetsns(struct vdso_data *vdso)
 104 {
 105         u32 cycle_now;
 106         u32 cycle_delta;
 107         u32 *timer_cycle_base;
 108
 109         timer_cycle_base =
 110             (u32 *) ((char *)__get_timerpage() + vdso->cycle_count_offset);
 111         cycle_now = readl_relaxed(timer_cycle_base);
 112         if (true == vdso->cycle_count_down)
 113                 cycle_now = ~(*timer_cycle_base);
 114         cycle_delta = cycle_now - (u32) vdso->cs_cycle_last;
 115         return ((u64) cycle_delta & vdso->cs_mask) * vdso->cs_mult;
 116 }
 117
 118 static notrace int do_realtime(struct timespec *ts, struct vdso_data *vdata)
 119 {
 120         unsigned count;
 121         u64 ns;
 122         do {
 123                 count = vdso_read_begin(vdata);
 124                 ts->tv_sec = vdata->xtime_clock_sec;
 125                 ns = vdata->xtime_clock_nsec;
 126                 ns += vgetsns(vdata);
 127                 ns >>= vdata->cs_shift;
 128         } while (vdso_read_retry(vdata, count));
 129
 130         ts->tv_sec += __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns);
 131         ts->tv_nsec = ns;
 132
 133         return 0;
 134 }
 135
 136 static notrace int do_monotonic(struct timespec *ts, struct vdso_data *vdata)
 137 {
 138         struct timespec tomono;
 139         u64 nsecs;
 140         u32 seq;
 141
 142         do {
 143                 seq = vdso_read_begin(vdata);
 144
 145                 ts->tv_sec = vdata->xtime_clock_sec;
 146                 nsecs = vdata->xtime_clock_nsec;
 147                 nsecs += vgetsns(vdata);
 148                 nsecs >>= vdata->cs_shift;
 149
 150                 tomono.tv_sec = vdata->wtm_clock_sec;
 151                 tomono.tv_nsec = vdata->wtm_clock_nsec;
 152
 153         } while (vdso_read_retry(vdata, seq));
 154
 155         ts->tv_sec += tomono.tv_sec;
 156         ts->tv_nsec = 0;
 157         timespec_add_ns(ts, nsecs + tomono.tv_nsec);
 158         return 0;
 159 }
 160
 161 notrace int __vdso_clock_gettime(clockid_t clkid, struct timespec *ts)
 162 {
 163         struct vdso_data *vdata;
 164         int ret = -1;
 165
 166         vdata = __get_datapage();
 167         if (vdata->cycle_count_offset == EMPTY_REG_OFFSET)
 168                 return clock_gettime_fallback(clkid, ts);
 169
 170         switch (clkid) {
 171         case CLOCK_REALTIME_COARSE:
 172                 ret = do_realtime_coarse(ts, vdata);
 173                 break;
 174         case CLOCK_MONOTONIC_COARSE:
 175                 ret = do_monotonic_coarse(ts, vdata);
 176                 break;
 177         case CLOCK_REALTIME:
 178                 ret = do_realtime(ts, vdata);
 179                 break;
 180         case CLOCK_MONOTONIC:
 181                 ret = do_monotonic(ts, vdata);
 182                 break;
 183         default:
 184                 break;
 185         }
 186
 187         if (ret)
 188                 ret = clock_gettime_fallback(clkid, ts);
 189
 190         return ret;
 191 }
 192
 193 static notrace int clock_getres_fallback(clockid_t _clk_id,
 194                                           struct timespec *_res)
 195 {
 196         register clockid_t clk_id asm("$r0") = _clk_id;
 197         register struct timespec *res asm("$r1") = _res;
 198         register int ret asm("$r0");
 199
 200         asm volatile ("movi     $r15, %3\n"
 201                       "syscall  0x0\n"
 202                       :"=r" (ret)
 203                       :"r"(clk_id), "r"(res), "i"(__NR_clock_getres)
 204                       :"$r15", "memory");
 205
 206         return ret;
 207 }
 208
 209 notrace int __vdso_clock_getres(clockid_t clk_id, struct timespec *res)
 210 {
 211         if (res == NULL)
 212                 return 0;
 213         switch (clk_id) {
 214         case CLOCK_REALTIME:
 215         case CLOCK_MONOTONIC:
 216         case CLOCK_MONOTONIC_RAW:
 217                 res->tv_sec = 0;
 218                 res->tv_nsec = CLOCK_REALTIME_RES;
 219                 break;
 220         case CLOCK_REALTIME_COARSE:
 221         case CLOCK_MONOTONIC_COARSE:
 222                 res->tv_sec = 0;
 223                 res->tv_nsec = CLOCK_COARSE_RES;
 224                 break;
 225         default:
 226                 return clock_getres_fallback(clk_id, res);
 227         }
 228         return 0;
 229 }
 230
 231 static notrace inline int gettimeofday_fallback(struct timeval *_tv,
 232                                                 struct timezone *_tz)
 233 {
 234         register struct timeval *tv asm("$r0") = _tv;
 235         register struct timezone *tz asm("$r1") = _tz;
 236         register int ret asm("$r0");
 237
 238         asm volatile ("movi     $r15, %3\n"
 239                       "syscall  0x0\n"
 240                       :"=r" (ret)
 241                       :"r"(tv), "r"(tz), "i"(__NR_gettimeofday)
 242                       :"$r15", "memory");
 243
 244         return ret;
 245 }
 246
 247 notrace int __vdso_gettimeofday(struct timeval *tv, struct timezone *tz)
 248 {
 249         struct timespec ts;
 250         struct vdso_data *vdata;
 251         int ret;
 252
 253         vdata = __get_datapage();
 254
 255         if (vdata->cycle_count_offset == EMPTY_REG_OFFSET)
 256                 return gettimeofday_fallback(tv, tz);
 257
 258         ret = do_realtime(&ts, vdata);
 259
 260         if (tv) {
 261                 tv->tv_sec = ts.tv_sec;
 262                 tv->tv_usec = ts.tv_nsec / 1000;
 263         }
 264         if (tz) {
 265                 tz->tz_minuteswest = vdata->tz_minuteswest;
 266                 tz->tz_dsttime = vdata->tz_dsttime;
 267         }
 268
 269         return ret;
 270 }