4c4fae147d
this will allow to always call poller_call even durring timeout and still the case in getc Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
182 lines
5.1 KiB
C
182 lines
5.1 KiB
C
/*
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* clock.c - generic clocksource implementation
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*
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* This file contains the clocksource implementation from the Linux
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* kernel originally by John Stultz
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*
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* Copyright (C) 2004, 2005 IBM, John Stultz (johnstul@us.ibm.com)
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* Copyright (c) 2007 Sascha Hauer <s.hauer@pengutronix.de>, Pengutronix
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*
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* See file CREDITS for list of people who contributed to this
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* project.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2
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* as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include <common.h>
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#include <asm-generic/div64.h>
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#include <clock.h>
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#include <poller.h>
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static struct clocksource *current_clock;
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static uint64_t time_ns;
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/**
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* get_time_ns - get current timestamp in nanoseconds
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*/
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uint64_t get_time_ns(void)
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{
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struct clocksource *cs = current_clock;
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uint64_t cycle_now, cycle_delta;
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uint64_t ns_offset;
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/* read clocksource: */
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cycle_now = cs->read() & cs->mask;
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/* calculate the delta since the last call: */
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cycle_delta = (cycle_now - cs->cycle_last) & cs->mask;
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/* convert to nanoseconds: */
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ns_offset = cyc2ns(cs, cycle_delta);
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cs->cycle_last = cycle_now;
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time_ns += ns_offset;
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return time_ns;
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}
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EXPORT_SYMBOL(get_time_ns);
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/**
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* clocks_calc_mult_shift - calculate mult/shift factors for scaled math of clocks
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* @mult: pointer to mult variable
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* @shift: pointer to shift variable
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* @from: frequency to convert from
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* @to: frequency to convert to
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* @maxsec: guaranteed runtime conversion range in seconds
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*
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* The function evaluates the shift/mult pair for the scaled math
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* operations of clocksources and clockevents.
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*
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* @to and @from are frequency values in HZ. For clock sources @to is
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* NSEC_PER_SEC == 1GHz and @from is the counter frequency. For clock
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* event @to is the counter frequency and @from is NSEC_PER_SEC.
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*
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* The @maxsec conversion range argument controls the time frame in
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* seconds which must be covered by the runtime conversion with the
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* calculated mult and shift factors. This guarantees that no 64bit
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* overflow happens when the input value of the conversion is
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* multiplied with the calculated mult factor. Larger ranges may
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* reduce the conversion accuracy by chosing smaller mult and shift
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* factors.
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*/
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void clocks_calc_mult_shift(uint32_t *mult, uint32_t *shift, uint32_t from, uint32_t to, uint32_t maxsec)
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{
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uint64_t tmp;
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uint32_t sft, sftacc = 32;
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/*
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* Calculate the shift factor which is limiting the conversion
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* range:
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*/
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tmp = ((uint64_t)maxsec * from) >> 32;
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while (tmp) {
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tmp >>=1;
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sftacc--;
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}
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/*
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* Find the conversion shift/mult pair which has the best
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* accuracy and fits the maxsec conversion range:
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*/
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for (sft = 32; sft > 0; sft--) {
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tmp = (uint64_t) to << sft;
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tmp += from / 2;
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do_div(tmp, from);
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if ((tmp >> sftacc) == 0)
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break;
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}
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*mult = tmp;
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*shift = sft;
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}
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/**
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* clocksource_hz2mult - calculates mult from hz and shift
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* @hz: Clocksource frequency in Hz
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* @shift_constant: Clocksource shift factor
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*
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* Helper functions that converts a hz counter
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* frequency to a timsource multiplier, given the
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* clocksource shift value
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*/
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uint32_t clocksource_hz2mult(uint32_t hz, uint32_t shift_constant)
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{
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/* hz = cyc/(Billion ns)
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* mult/2^shift = ns/cyc
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* mult = ns/cyc * 2^shift
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* mult = 1Billion/hz * 2^shift
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* mult = 1000000000 * 2^shift / hz
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* mult = (1000000000<<shift) / hz
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*/
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uint64_t tmp = ((uint64_t)1000000000) << shift_constant;
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tmp += hz/2; /* round for do_div */
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do_div(tmp, hz);
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return (uint32_t)tmp;
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}
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int is_timeout(uint64_t start_ns, uint64_t time_offset_ns)
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{
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if (time_offset_ns >= 100 * USECOND)
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poller_call();
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if ((int64_t)(start_ns + time_offset_ns - get_time_ns()) < 0)
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return 1;
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else
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return 0;
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}
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EXPORT_SYMBOL(is_timeout);
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void ndelay(unsigned long nsecs)
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{
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uint64_t start = get_time_ns();
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while(!is_timeout(start, nsecs));
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}
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EXPORT_SYMBOL(ndelay);
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void udelay(unsigned long usecs)
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{
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uint64_t start = get_time_ns();
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while(!is_timeout(start, usecs * USECOND));
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}
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EXPORT_SYMBOL(udelay);
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void mdelay(unsigned long msecs)
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{
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uint64_t start = get_time_ns();
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while(!is_timeout(start, msecs * MSECOND));
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}
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EXPORT_SYMBOL(mdelay);
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int init_clock(struct clocksource *cs)
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{
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current_clock = cs;
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return 0;
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}
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