Date: Thu, 14 Jun 2018 17:18:15 +0000 (UTC) From: Emmanuel Vadot <manu@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r335156 - head/sys/arm/arm Message-ID: <201806141718.w5EHIFnE093607@repo.freebsd.org>
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Author: manu Date: Thu Jun 14 17:18:15 2018 New Revision: 335156 URL: https://svnweb.freebsd.org/changeset/base/335156 Log: arm timer: Add workaround for Allwinner A64 timer The timer present in allwinner A64 SoC is unstable, value can jump backward or forward. It was found that when bit 11 and upper roll over the low bits can sometimes being read as all as 1 or all as 0. Simply ignore the values for those cases. Modified: head/sys/arm/arm/generic_timer.c Modified: head/sys/arm/arm/generic_timer.c ============================================================================== --- head/sys/arm/arm/generic_timer.c Thu Jun 14 17:09:33 2018 (r335155) +++ head/sys/arm/arm/generic_timer.c Thu Jun 14 17:18:15 2018 (r335156) @@ -92,6 +92,7 @@ __FBSDID("$FreeBSD$"); struct arm_tmr_softc { struct resource *res[4]; void *ihl[4]; + uint64_t (*get_cntxct)(bool); uint32_t clkfreq; struct eventtimer et; bool physical; @@ -142,6 +143,28 @@ get_freq(void) } static uint64_t +get_cntxct_a64_unstable(bool physical) +{ + uint64_t val +; + isb(); + if (physical) { + do { + val = get_el0(cntpct); + } + while (((val + 1) & 0x7FF) <= 1); + } + else { + do { + val = get_el0(cntvct); + } + while (((val + 1) & 0x7FF) <= 1); + } + + return (val); +} + +static uint64_t get_cntxct(bool physical) { uint64_t val; @@ -226,7 +249,7 @@ static unsigned arm_tmr_get_timecount(struct timecounter *tc) { - return (get_cntxct(arm_tmr_sc->physical)); + return (arm_tmr_sc->get_cntxct(arm_tmr_sc->physical)); } static int @@ -379,6 +402,7 @@ arm_tmr_attach(device_t dev) if (arm_tmr_sc) return (ENXIO); + sc->get_cntxct = &get_cntxct_a64_unstable; #ifdef FDT /* Get the base clock frequency */ node = ofw_bus_get_node(dev); @@ -387,6 +411,13 @@ arm_tmr_attach(device_t dev) sizeof(clock)); if (error > 0) sc->clkfreq = clock; + + if (OF_hasprop(node, "allwinner,sun50i-a64-unstable-timer")) { + sc->get_cntxct = &get_cntxct_a64_unstable; + if (bootverbose) + device_printf(dev, + "Enabling allwinner unstable timer workaround\n"); + } } #endif @@ -518,10 +549,10 @@ arm_tmr_do_delay(int usec, void *arg) else counts = usec * counts_per_usec; - first = get_cntxct(sc->physical); + first = sc->get_cntxct(sc->physical); while (counts > 0) { - last = get_cntxct(sc->physical); + last = sc->get_cntxct(sc->physical); counts -= (int32_t)(last - first); first = last; }
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