On Thu, Jul 10, 2008 at 11:46:45AM +0200, Wolfgang Denk wrote:
In message 20080710093001.GR4595@pengutronix.de you wrote:
How about using the Linux clocksource framework for U-Boot? I did this
I have to admit that I don't know how big that code is?
Somewhere next to nothing:
/* * clock.c - generic clocksource implementation * * This file contains the clocksource implementation from the Linux * kernel originally by John Stultz * * Copyright (C) 2004, 2005 IBM, John Stultz (johnstul@us.ibm.com) * Copyright (c) 2007 Sascha Hauer s.hauer@pengutronix.de, Pengutronix * * 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 version 2 * as published by the Free Software Foundation. * * 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 */
#include <common.h> #include <asm-generic/div64.h> #include <clock.h>
static struct clocksource *current_clock; static uint64_t time_ns;
/** * get_time_ns - get current timestamp in nanoseconds */ uint64_t get_time_ns(void) { struct clocksource *cs = current_clock; uint64_t cycle_now, cycle_delta; uint64_t ns_offset;
/* read clocksource: */ cycle_now = cs->read();
/* calculate the delta since the last call: */ cycle_delta = (cycle_now - cs->cycle_last) & cs->mask;
/* convert to nanoseconds: */ ns_offset = cyc2ns(cs, cycle_delta);
cs->cycle_last = cycle_now;
time_ns += ns_offset; return time_ns; } EXPORT_SYMBOL(get_time_ns);
/** * clocksource_hz2mult - calculates mult from hz and shift * @hz: Clocksource frequency in Hz * @shift_constant: Clocksource shift factor * * Helper functions that converts a hz counter * frequency to a timsource multiplier, given the * clocksource shift value */ uint32_t clocksource_hz2mult(uint32_t hz, uint32_t shift_constant) { /* hz = cyc/(Billion ns) * mult/2^shift = ns/cyc * mult = ns/cyc * 2^shift * mult = 1Billion/hz * 2^shift * mult = 1000000000 * 2^shift / hz * mult = (1000000000<<shift) / hz */ uint64_t tmp = ((uint64_t)1000000000) << shift_constant;
tmp += hz/2; /* round for do_div */ do_div(tmp, hz);
return (uint32_t)tmp; }
int is_timeout(uint64_t start_ns, uint64_t time_offset_ns) {
if (start_ns + time_offset_ns < get_time_ns()) return 1; else return 0; } EXPORT_SYMBOL(is_timeout);
void udelay(unsigned long usecs) { uint64_t start = get_time_ns();
while(!is_timeout(start, usecs * 1000)); } EXPORT_SYMBOL(udelay);
void mdelay(unsigned long msecs) { uint64_t start = get_time_ns();
while(!is_timeout(start, msecs * 1000000)); } EXPORT_SYMBOL(mdelay);
int init_clock(struct clocksource *cs) { current_clock = cs; return 0; }
The clocksource driver itself adds another 100 lines of code (for mx31). The implementation of udelay shows how to implement timeouts, the main usage of timing functions.
Regards, Sascha