u-boot/cpu/mpc8260/speed.h
2001-04-28 17:59:11 +00:00

54 lines
1.8 KiB
C

/*
* (C) Copyright 2000
* Wolfgang Denk, DENX Software Engineering, wd@denx.de.
*
* See file CREDITS for list of people who contributed to this
* project.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of
* the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
* MA 02111-1307 USA
*/
/*-----------------------------------------------------------------------
* Timer value for timer 2, ICLK = 10
*
* SPEED_FCOUNT2 = GCLK / (16 * (TIMER_TMR_PS + 1))
* SPEED_TMR3_PS = (GCLK / (16 * SPEED_FCOUNT3)) - 1
*
* SPEED_FCOUNT2 timer 2 counting frequency
* GCLK CPU clock
* SPEED_TMR2_PS prescaler
*/
#define SPEED_TMR2_PS (250 - 1) /* divide by 250 */
/*-----------------------------------------------------------------------
* Timer value for PIT
*
* PIT_TIME = SPEED_PITC / PITRTCLK
* PITRTCLK = 8192
*/
#define SPEED_PITC (82 << 16) /* start counting from 82 */
/*
* The new value for PTA is calculated from
*
* PTA = (gclk * Trefresh) / (2 ^ (2 * DFBRG) * PTP * NCS)
*
* gclk CPU clock (not bus clock !)
* Trefresh Refresh cycle * 4 (four word bursts used)
* DFBRG For normal mode (no clock reduction) always 0
* PTP Prescaler (already adjusted for no. of banks and 4K / 8K refresh)
* NCS Number of SDRAM banks (chip selects) on this UPM.
*/