gonzui

    1: /*
    2:  *----------------------------------------------------------------------
    3:  *    T-Kernel 2.0 Software Package
    4:  *
    5:  *    Copyright 2011 by Ken Sakamura.
    6:  *    This software is distributed under the latest version of T-License 2.x.
    7:  *----------------------------------------------------------------------
    8:  *
    9:  *    Released by T-Engine Forum(http://www.t-engine.org/) at 2011/05/17.
   10:  *    Modified by TRON Forum(http://www.tron.org/) at 2015/06/01.
   11:  *
   12:  *----------------------------------------------------------------------
   13:  */
   14: 
   15: /*
   16:  *      Calculate the value of required count for loop-wait for a given period (in micro seconds)
   17:  */
   18: 
   19: #include <basic.h>
   20: #include <sys/sysinfo.h>
   21: #include <tk/syslib.h>
   22: #include "tkdev_conf.h"
   23: 
   24: /*
   25:  * Loop wait
   26:  *      disable the inline expansion caused by compiler optimization to obtain accurate
   27:  *      measurement.
   28:  */
   29: __attribute__ ((noinline))
   30: LOCAL void WaitLoop( UW count )
   31: {
   32:         Asm("  _loop:   subs      %0, %0, #1   \n"
   33:         "              bhi _loop           "
   34:                 : "=r"(count)
   35:                 : "0"(count + 1)
   36:         );
   37: }
   38: 
   39: /*
   40:  * WaitUsec()  calculate the loop count for a given time (in microseconds)
   41:  *      interrupt-disabled state is assumed.
   42:  */
   43: EXPORT void CountWaitUsec( void )
   44: {
   45:         UW     t0, t1, t2;
   46:         UW     cnt;
   47:         UW     d;
   48: 
   49:         /* stop timer */
   50:         out_w(TI_OP, 0);
   51: 
   52:         /* select clock */
   53:         out_w(TI0TIN_SEL, (in_w(TI0TIN_SEL) & ~3) | TITIN_PLL3);
   54: 
   55:         /* supply clock */
   56:         out_w(GCLKCTRL3ENA, in_w(GCLKCTRL3ENA) | TI0_TIN_GCK);
   57:         out_w(GCLKCTRL3,    in_w(GCLKCTRL3)    | TI0_TIN_GCK);
   58: 
   59:         /* enable timer */
   60:         out_w(TI_OP, TM_EN);
   61:         while ( (in_w(TI_SCLR) & TM_SCLR) != 0 );
   62:         WaitLoop(100);
   63: 
   64:         /* set counter */
   65:         out_w(TI_SET, 0xffffffff);
   66: 
   67:         /* start timer counting */
   68:         out_w(TI_OP, TSTART|TM_EN);
   69: 
   70:         WaitLoop(100);         /* wait for a little (just in case) */
   71: 
   72:         /* measurement */
   73:         t0 = in_w(TI_RCR);
   74:         WaitLoop(1001);
   75:         t1 = in_w(TI_RCR);
   76:         WaitLoop(21001);
   77:         t2 = in_w(TI_RCR);
   78: 
   79:         /* stop timer */
   80:         out_w(TI_OP, 0);
   81: 
   82:         /* stop clock */
   83:         out_w(GCLKCTRL3, in_w(GCLKCTRL3) & ~TI0_TIN_GCK);
   84: 
   85:         /* the time for 20000 loops is calculated excluding the
   86:            overhead for the rest of measurement time. */
   87:         cnt = (t2 - t1) - (t1 - t0);
   88: 
   89:         /* Calculate the loop count that spends 64 microseconds
   90:          *                      20000 loops
   91:          *     loop64us = ---------------------- * 64usec
   92:          *                  cnt * (1 / TIN_CLK)
   93:          *     TIN_CLK = input clock to the timer [Hz]
   94:          */
   95:         d = in_w(DIVTIMTIN);
   96:         SCInfo.loop64us = TIN_CLK(d) / (cnt * (50/2)) * (64/2);
   97: }