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   1 /******************************************************************************
   2 *
   3 * Copyright (C) 2014 - 2016 Xilinx, Inc. All rights reserved.
   4 *
   5 * Permission is hereby granted, free of charge, to any person obtaining a copy
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  10 * furnished to do so, subject to the following conditions:
  11 *
  12 * The above copyright notice and this permission notice shall be included in
  13 * all copies or substantial portions of the Software.
  14 *
  15 * Use of the Software is limited solely to applications:
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  18 *
  19 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  20 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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  29 * this Software without prior written authorization from Xilinx.
  30 *
  31 ******************************************************************************/
  32 /*****************************************************************************/
  33 /**
  34 *
  35 * @file usleep.c
  36 *
  37 * This function provides a microsecond delay using the Global Timer register in
  38 * the ARM Cortex R5 MP core.
  39 *
  40 * <pre>
  41 * MODIFICATION HISTORY:
  42 *
  43 * Ver   Who      Date     Changes
  44 * ----- -------- -------- -----------------------------------------------
  45 * 5.00  pkp      02/20/14 First release
  46 * 5.04  pkp              02/19/16 usleep routine is modified to use TTC3 if present
  47 *                                                 else it will use set of assembly instructions to
  48 *                                                 provide the required delay
  49 * 5.04  pkp              03/09/16 Assembly routine for usleep is modified to avoid
  50 *                                                 disabling the interrupt
  51 * 5.04  pkp              03/11/16 Compare the counter value to previously read value
  52 *                                                 to detect the overflow for TTC3
  53 * 6.0   asa      08/15/16 Updated the usleep signature. Fix for CR#956899.
  54 * </pre>
  55 *
  56 ******************************************************************************/
  57 /***************************** Include Files *********************************/
  58
  59 #include "sleep.h"
  60 #include "xtime_l.h"
  61 #include "xparameters.h"
  62 #include "xil_types.h"
  63 #include "xpseudo_asm.h"
  64 #include "xreg_cortexr5.h"
  65
  66 /*****************************************************************************/
  67 /**
  68 *
  69 * This API gives a delay in microseconds
  70 *
  71 * @param        useconds requested
  72 *
  73 * @return       0 always
  74 *
  75 * @note         The usleep API is implemented using TTC3 counter 0 timer if present
  76 *                       When TTC3 is absent, usleep is implemented using assembly
  77 *                       instructions which is tested with instruction and data caches
  78 *                       enabled and it gives proper delay. It may give more delay than
  79 *                       exepcted when caches are disabled. If interrupt comes when usleep
  80 *                       using assembly instruction is being executed, the delay may be
  81 *                       greater than what is expected since once the interrupt is served
  82 *                       count resumes from where it was interrupted unlike the case of TTC3
  83 *                       where counter keeps running while interrupt is being served.
  84 *
  85 ****************************************************************************/
  86
  87 int usleep(unsigned long useconds)
  88 {
  89
  90 #ifdef SLEEP_TIMER_BASEADDR
  91         u64 tEnd;
  92         u64 tCur;
  93         u32 TimeHighVal;
  94         XTime TimeLowVal1;
  95         XTime TimeLowVal2;
  96
  97         TimeHighVal = 0;
  98
  99         XTime_GetTime(&TimeLowVal1);
 100         tEnd  = (u64)TimeLowVal1 + (((u64) useconds) * COUNTS_PER_USECOND);
 101
 102         do
 103         {
 104                 XTime_GetTime(&TimeLowVal2);
 105             if (TimeLowVal2 < TimeLowVal1) {
 106                                 TimeHighVal++;
 107                 }
 108                 TimeLowVal1 = TimeLowVal2;
 109                 tCur = (((u64) TimeHighVal) << 32U) | (u64)TimeLowVal2;
 110         } while (tCur < tEnd);
 111
 112         return 0;
 113 #else
 114         __asm__ __volatile__ (
 115                         " push {r0,r1}          \n\t"
 116                         " mov r0, %[usec]       \n\t"
 117                         " 1: \n\t"
 118                         " mov r1, %[iter]       \n\t"
 119                         " 2:                            \n\t"
 120                         " subs r1, r1, #0x1 \n\t"
 121                         " bne   2b              \n\t"
 122                         " subs r0,r0,#0x1       \n\t"
 123                         "  bne 1b                       \n\t"
 124                         " pop {r0,r1}           \n\t"
 125                         :: [iter] "r" (ITERS_PER_USEC), [usec] "r" (useconds)
 126         );
 127 #endif
 128 }