lib/eal/riscv/rte_cycles.c

   1 /* SPDX-License-Identifier: BSD-3-Clause
   2  * Copyright(c) 2015 Cavium, Inc
   3  * Copyright(c) 2022 StarFive
   4  * Copyright(c) 2022 SiFive
   5  * Copyright(c) 2022 Semihalf
   6  */
   7
   8 #include <stdio.h>
   9
  10 #include "eal_private.h"
  11 #include "rte_byteorder.h"
  12 #include "rte_cycles.h"
  13 #include "rte_log.h"
  14
  15 /** Read generic counter frequency */
  16 static uint64_t
  17 __rte_riscv_timefrq(void)
  18 {
  19 #define TIMEBASE_FREQ_SIZE      8
  20         if (RTE_RISCV_TIME_FREQ > 0)
  21                 return RTE_RISCV_TIME_FREQ;
  22         uint8_t buf[TIMEBASE_FREQ_SIZE];
  23         ssize_t cnt;
  24         FILE *file;
  25
  26         file = fopen("/proc/device-tree/cpus/timebase-frequency", "rb");
  27         if (!file)
  28                 goto fail;
  29
  30         cnt = fread(buf, 1, TIMEBASE_FREQ_SIZE, file);
  31         fclose(file);
  32         switch (cnt) {
  33         case 8:
  34                 return rte_be_to_cpu_64(*(uint64_t *)buf);
  35         case 4:
  36                 return rte_be_to_cpu_32(*(uint32_t *)buf);
  37         default:
  38                 break;
  39         }
  40 fail:
  41         RTE_LOG(WARNING, EAL, "Unable to read timebase-frequency from FDT.\n");
  42         return 0;
  43 }
  44
  45 uint64_t
  46 get_tsc_freq_arch(void)
  47 {
  48         RTE_LOG(NOTICE, EAL, "TSC using RISC-V %s.\n",
  49                 RTE_RISCV_RDTSC_USE_HPM ? "rdcycle" : "rdtime");
  50         if (!RTE_RISCV_RDTSC_USE_HPM)
  51                 return __rte_riscv_timefrq();
  52 #define CYC_PER_1MHZ 1E6
  53         /*
  54          * Use real time clock to estimate current cycle frequency
  55          */
  56         uint64_t ticks, frq;
  57         uint64_t start_ticks, cur_ticks;
  58         uint64_t start_cycle, end_cycle;
  59
  60         /* Do not proceed unless clock frequency can be obtained. */
  61         frq = __rte_riscv_timefrq();
  62         if (!frq)
  63                 return 0;
  64
  65         /* Number of ticks for 1/10 second */
  66         ticks = frq / 10;
  67
  68         start_ticks = __rte_riscv_rdtime_precise();
  69         start_cycle = rte_rdtsc_precise();
  70         do {
  71                 cur_ticks = __rte_riscv_rdtime();
  72         } while ((cur_ticks - start_ticks) < ticks);
  73         end_cycle = rte_rdtsc_precise();
  74
  75         /* Adjust the cycles to next 1Mhz */
  76         return RTE_ALIGN_MUL_CEIL((end_cycle - start_cycle) * 10, CYC_PER_1MHZ);
  77 }