board/sandpoint/speed.h

   1 /*
   2  * (C) Copyright 2000
   3  * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
   4  *
   5  * SPDX-License-Identifier:     GPL-2.0+
   6  */
   7
   8 /*-----------------------------------------------------------------------
   9  * Timer value for timer 2, ICLK = 10
  10  *
  11  * SPEED_FCOUNT2 =  GCLK / (16 * (TIMER_TMR_PS + 1))
  12  * SPEED_TMR3_PS = (GCLK / (16 * SPEED_FCOUNT3)) - 1
  13  *
  14  * SPEED_FCOUNT2        timer 2 counting frequency
  15  * GCLK                 CPU clock
  16  * SPEED_TMR2_PS        prescaler
  17  */
  18 #define SPEED_TMR2_PS   (250 - 1)       /* divide by 250        */
  19
  20 /*-----------------------------------------------------------------------
  21  * Timer value for PIT
  22  *
  23  * PIT_TIME = SPEED_PITC / PITRTCLK
  24  * PITRTCLK = 8192
  25  */
  26 #define SPEED_PITC      (82 << 16)      /* start counting from 82       */
  27
  28 /*
  29  * The new value for PTA is calculated from
  30  *
  31  *      PTA = (gclk * Trefresh) / (2 ^ (2 * DFBRG) * PTP * NCS)
  32  *
  33  * gclk         CPU clock (not bus clock !)
  34  * Trefresh     Refresh cycle * 4 (four word bursts used)
  35  * DFBRG        For normal mode (no clock reduction) always 0
  36  * PTP          Prescaler (already adjusted for no. of banks and 4K / 8K refresh)
  37  * NCS          Number of SDRAM banks (chip selects) on this UPM.
  38  */