/*
 * linux/kernel/time/timecounter.c
 *
 * based on code that migrated away from
 * linux/kernel/time/clocksource.c
 *
 * 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.
 */

#include <linux/export.h>
#include <linux/timecounter.h>

void timecounter_init(struct timecounter *tc,
		      const struct cyclecounter *cc,
		      u64 start_tstamp)
{
	tc->cc = cc;
	tc->cycle_last = cc->read(cc);
	tc->nsec = start_tstamp;
	tc->mask = (1ULL << cc->shift) - 1;
	tc->frac = 0;
}
EXPORT_SYMBOL_GPL(timecounter_init);

/**
 * timecounter_read_delta - get nanoseconds since last call of this function
 * @tc:         Pointer to time counter
 *
 * When the underlying cycle counter runs over, this will be handled
 * correctly as long as it does not run over more than once between
 * calls.
 *
 * The first call to this function for a new time counter initializes
 * the time tracking and returns an undefined result.
 */
static u64 timecounter_read_delta(struct timecounter *tc)
{
	u64 cycle_now, cycle_delta;
	u64 ns_offset;

	/* read cycle counter: */
	cycle_now = tc->cc->read(tc->cc);

	/* calculate the delta since the last timecounter_read_delta(): */
	cycle_delta = (cycle_now - tc->cycle_last) & tc->cc->mask;

	/* convert to nanoseconds: */
	ns_offset = cyclecounter_cyc2ns(tc->cc, cycle_delta,
					tc->mask, &tc->frac);

	/* update time stamp of timecounter_read_delta() call: */
	tc->cycle_last = cycle_now;

	return ns_offset;
}

u64 timecounter_read(struct timecounter *tc)
{
	u64 nsec;

	/* increment time by nanoseconds since last call */
	nsec = timecounter_read_delta(tc);
	nsec += tc->nsec;
	tc->nsec = nsec;

	return nsec;
}
EXPORT_SYMBOL_GPL(timecounter_read);

/*
 * This is like cyclecounter_cyc2ns(), but it is used for computing a
 * time previous to the time stored in the cycle counter.
 */
static u64 cc_cyc2ns_backwards(const struct cyclecounter *cc,
			       u64 cycles, u64 mask, u64 frac)
{
	u64 ns = (u64) cycles;

	ns = ((ns * cc->mult) - frac) >> cc->shift;

	return ns;
}

u64 timecounter_cyc2time(struct timecounter *tc,
			 u64 cycle_tstamp)
{
	u64 delta = (cycle_tstamp - tc->cycle_last) & tc->cc->mask;
	u64 nsec = tc->nsec, frac = tc->frac;

	/*
	 * Instead of always treating cycle_tstamp as more recent
	 * than tc->cycle_last, detect when it is too far in the
	 * future and treat it as old time stamp instead.
	 */
	if (delta > tc->cc->mask / 2) {
		delta = (tc->cycle_last - cycle_tstamp) & tc->cc->mask;
		nsec -= cc_cyc2ns_backwards(tc->cc, delta, tc->mask, frac);
	} else {
		nsec += cyclecounter_cyc2ns(tc->cc, delta, tc->mask, &frac);
	}

	return nsec;
}
EXPORT_SYMBOL_GPL(timecounter_cyc2time);
usb/c67x00?id=4283bce5f8c2307d47313e0429e5f1357c43023d&amp;showmsg=1'>c67x00</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/cgit.cgi/linux/net-next.git/log/drivers/usb/c67x00?id=4283bce5f8c2307d47313e0429e5f1357c43023d'>Collapse</a>)</th><th class='left'>Author</th><th class='left'>Files</th><th class='left'>Lines</th></tr>
'35'>35</option><option value='40'>40</option></select></td></tr><tr><td class='label'>space:</td><td class='ctrl'><select name='ignorews' onchange='this.form.submit();'><option value='0' selected='selected'>include</option><option value='1'>ignore</option></select></td></tr><tr><td class='label'>mode:</td><td class='ctrl'><select name='dt' onchange='this.form.submit();'><option value='0' selected='selected'>unified</option><option value='1'>ssdiff</option><option value='2'>stat only</option></select></td></tr><tr><td/><td class='ctrl'><noscript><input type='submit' value='reload'/></noscript></td></tr></table></form></div><table summary='commit info' class='commit-info'>
<tr><th>author</th><td>Lukasz Majewski &lt;lukma@denx.de&gt;</td><td class='right'>2017-02-07 06:20:24 +0100</td></tr>
<tr><th>committer</th><td>David S. Miller &lt;davem@davemloft.net&gt;</td><td class='right'>2017-02-07 13:59:27 -0500</td></tr>
<tr><th>commit</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/drivers?id=ac6e058b75be71208e98a5808453aae9a17be480'>ac6e058b75be71208e98a5808453aae9a17be480</a> (<a href='/cgit.cgi/linux/net-next.git/patch/drivers?id=ac6e058b75be71208e98a5808453aae9a17be480'>patch</a>)</td></tr>
<tr><th>tree</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/tree/?id=ac6e058b75be71208e98a5808453aae9a17be480'>559b0039d832be0016c2f200e4376299ef7a5ced</a> /<a href='/cgit.cgi/linux/net-next.git/tree/drivers?id=ac6e058b75be71208e98a5808453aae9a17be480'>drivers</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/drivers?id=fc6d39c39581f3c12c95f166ce95ef8beb2047e8'>fc6d39c39581f3c12c95f166ce95ef8beb2047e8</a> (<a href='/cgit.cgi/linux/net-next.git/diff/drivers?id=ac6e058b75be71208e98a5808453aae9a17be480&amp;id2=fc6d39c39581f3c12c95f166ce95ef8beb2047e8'>diff</a>)</td></tr></table>
<div class='commit-subject'>net: phy: dp83867: Recover from "port mirroring" N/A MODE4</div><div class='commit-msg'>The DP83867 when not properly bootstrapped - especially with LED_0 pin -
can enter N/A MODE4 for "port mirroring" feature.

To provide normal operation of the PHY, one needs not only to explicitly
disable the port mirroring feature, but as well stop some IC internal
testing (which disables RGMII communication).

To do that the STRAP_STS1 (0x006E) register must be read and RESERVED bit
11 examined. When it is set, the another RESERVED bit (11) at PHYCR
(0x0010) register must be clear to disable testing mode and enable RGMII
communication.

Thorough explanation of the problem can be found at following e2e thread:
"DP83867IR: Problem with RESERVED bits in PHY Control Register (PHYCR) -
Linux driver"

https://e2e.ti.com/support/interface/ethernet/f/903/p/571313/2096954#2096954

Signed-off-by: Lukasz Majewski &lt;lukma@denx.de&gt;
Reviewed-by: Andrew Lunn &lt;andrew@lunn.ch&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
</div><div class='diffstat-header'><a href='/cgit.cgi/linux/net-next.git/diff/?id=ac6e058b75be71208e98a5808453aae9a17be480'>Diffstat</a> (limited to 'drivers')</div><table summary='diffstat' class='diffstat'>