/* * 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 #include 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); 4f299f7c51e472ae77'>root/drivers/usb/host/xhci-ring.c
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authorGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-02-03 22:19:15 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-02-03 22:19:15 +0100
commit424414947da3dd5cb0d60e4f299f7c51e472ae77 (patch)
treea4067480c4256c80ae8f8438a3e4bb88e32050bc /drivers/usb/host/xhci-ring.c
parenta3683e0c1410c5c8136a7a93b0336ce88d3b893a (diff)
parentd07830db1bdb254e4b50d366010b219286b8c937 (diff)
Merge tag 'usb-serial-4.10-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/johan/usb-serial into usb-linus
Johan writes: USB-serial fixes for v4.10-rc7 One more device ID for pl2303. Signed-off-by: Johan Hovold <johan@kernel.org>
Diffstat (limited to 'drivers/usb/host/xhci-ring.c')