1 /* 2 * linux/include/asm-arm/arch-omaha/timex.h 3 * 4 * Omaha architecture timex specifications 5 * 6 * Copyright (C) 1999-2002 ARM Limited 7 * 8 * This program is free software; you can redistribute it and/or modify 9 * it under the terms of the GNU General Public License as published by 10 * the Free Software Foundation; either version 2 of the License, or 11 * (at your option) any later version. 12 * 13 * This program is distributed in the hope that it will be useful, 14 * but WITHOUT ANY WARRANTY; without even the implied warranty of 15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16 * GNU General Public License for more details. 17 * 18 * You should have received a copy of the GNU General Public License 19 * along with this program; if not, write to the Free Software 20 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 21 */ 22 23 /* 24 * Always runs at (almost) 1Mhz. 25 * 26 * Time is derived as follows 27 * 28 * CLOCK_TICK_RATE = ((FCLK / 4) / (Prescaler + 1)) / 2 29 * 30 * Where FCLK = CPU Clock Rate = 133 MHz 31 * Prescaler = 16 32 * 33 * Therefore: 34 * CLOCK_TICK_RATE = (33.25 MHz / 17) / 2 35 * = 977941 Hz 36 */ 37 #define CLOCK_TICK_RATE (977941) 38