1/* 2 * linux/arch/arm/plat-versatile/sched-clock.c 3 * 4 * Copyright (C) 1999 - 2003 ARM Limited 5 * Copyright (C) 2000 Deep Blue Solutions Ltd 6 * 7 * This program is free software; you can redistribute it and/or modify 8 * it under the terms of the GNU General Public License as published by 9 * the Free Software Foundation; either version 2 of the License, or 10 * (at your option) any later version. 11 * 12 * This program is distributed in the hope that it will be useful, 13 * but WITHOUT ANY WARRANTY; without even the implied warranty of 14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15 * GNU General Public License for more details. 16 * 17 * You should have received a copy of the GNU General Public License 18 * along with this program; if not, write to the Free Software 19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 20 */ 21#include <linux/cnt32_to_63.h> 22#include <linux/io.h> 23#include <asm/div64.h> 24 25#include <mach/hardware.h> 26#include <mach/platform.h> 27 28#ifdef VERSATILE_SYS_BASE 29#define REFCOUNTER (__io_address(VERSATILE_SYS_BASE) + VERSATILE_SYS_24MHz_OFFSET) 30#endif 31 32#ifdef REALVIEW_SYS_BASE 33#define REFCOUNTER (__io_address(REALVIEW_SYS_BASE) + REALVIEW_SYS_24MHz_OFFSET) 34#endif 35 36/* 37 * This is the Realview and Versatile sched_clock implementation. This 38 * has a resolution of 41.7ns, and a maximum value of about 35583 days. 39 * 40 * The return value is guaranteed to be monotonic in that range as 41 * long as there is always less than 89 seconds between successive 42 * calls to this function. 43 */ 44unsigned long long sched_clock(void) 45{ 46 unsigned long long v = cnt32_to_63(readl(REFCOUNTER)); 47 48 /* the <<1 gets rid of the cnt_32_to_63 top bit saving on a bic insn */ 49 v *= 125<<1; 50 do_div(v, 3<<1); 51 52 return v; 53} 54