Module Name: src
Committed By: joerg
Date: Mon May 14 17:15:54 UTC 2018
Modified Files:
src/sys/arch/aarch64/include: armreg.h
src/sys/arch/arm/cortex: gtmr.c
src/sys/arch/arm/include: armreg.h
Log Message:
Workaround A-008585 errata in GTMR.
Register reads and writes may provide unstable results if the counter
hardware is active at the same time. This results in non-monotonic
counters seen by both the gtmr interrupt and time counter.
The loops are currently applied unconditionally, restricting them to
appropiate FDT markers can be applied later.
To generate a diff of this commit:
cvs rdiff -u -r1.9 -r1.10 src/sys/arch/aarch64/include/armreg.h
cvs rdiff -u -r1.26 -r1.27 src/sys/arch/arm/cortex/gtmr.c
cvs rdiff -u -r1.120 -r1.121 src/sys/arch/arm/include/armreg.h
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/arch/aarch64/include/armreg.h
diff -u src/sys/arch/aarch64/include/armreg.h:1.9 src/sys/arch/aarch64/include/armreg.h:1.10
--- src/sys/arch/aarch64/include/armreg.h:1.9 Sun Apr 1 04:35:03 2018
+++ src/sys/arch/aarch64/include/armreg.h Mon May 14 17:15:54 2018
@@ -1,4 +1,4 @@
-/* $NetBSD: armreg.h,v 1.9 2018/04/01 04:35:03 ryo Exp $ */
+/* $NetBSD: armreg.h,v 1.10 2018/05/14 17:15:54 joerg Exp $ */
/*-
* Copyright (c) 2014 The NetBSD Foundation, Inc.
@@ -1005,6 +1005,13 @@ gtmr_cntp_ctl_write(uint32_t val)
/*
* Counter-timer Virtual Timer TimerValue register
*/
+static inline uint32_t
+gtmr_cntv_tval_read(void)
+{
+
+ return reg_cntv_tval_el0_read();
+}
+
static inline void
gtmr_cntv_tval_write(uint32_t val)
{
Index: src/sys/arch/arm/cortex/gtmr.c
diff -u src/sys/arch/arm/cortex/gtmr.c:1.26 src/sys/arch/arm/cortex/gtmr.c:1.27
--- src/sys/arch/arm/cortex/gtmr.c:1.26 Mon May 14 17:11:38 2018
+++ src/sys/arch/arm/cortex/gtmr.c Mon May 14 17:15:54 2018
@@ -1,4 +1,4 @@
-/* $NetBSD: gtmr.c,v 1.26 2018/05/14 17:11:38 joerg Exp $ */
+/* $NetBSD: gtmr.c,v 1.27 2018/05/14 17:15:54 joerg Exp $ */
/*-
* Copyright (c) 2012 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: gtmr.c,v 1.26 2018/05/14 17:11:38 joerg Exp $");
+__KERNEL_RCSID(0, "$NetBSD: gtmr.c,v 1.27 2018/05/14 17:15:54 joerg Exp $");
#include <sys/param.h>
#include <sys/bus.h>
@@ -50,6 +50,51 @@ __KERNEL_RCSID(0, "$NetBSD: gtmr.c,v 1.2
#include <arm/cortex/gtmr_var.h>
#include <arm/cortex/mpcore_var.h>
+#define stable_write(reg) \
+static void \
+reg ## _stable_write(struct gtmr_softc *sc, uint64_t val) \
+{ \
+ static int max_retry = 0; \
+ int retry; \
+ reg ## _write(val); \
+ retry = 0; \
+ while (reg ## _read() != (val) && retry++ < 200) \
+ reg ## _write(val); \
+ if (retry > max_retry) { \
+ aprint_verbose_dev(sc->sc_dev, #reg "_write max retries %d -> %d\n", \
+ max_retry, retry); \
+ max_retry = retry; \
+ } \
+}
+
+stable_write(gtmr_cntv_tval);
+
+#define stable_read(reg) \
+static uint64_t \
+reg ## _stable_read(struct gtmr_softc *sc) \
+{ \
+ static int max_retry = 0; \
+ uint64_t oval, val; \
+ int retry = 0; \
+ val = reg ## _read(); \
+ while (++retry < 200) { \
+ oval = val; \
+ val = reg ## _read(); \
+ if (val == oval) \
+ break; \
+ } \
+ if (retry > max_retry) { \
+ aprint_verbose_dev(sc->sc_dev, #reg "_read max retries %d -> %d\n", \
+ max_retry, retry); \
+ max_retry = retry; \
+ } \
+ return val; \
+}
+
+stable_read(gtmr_cntv_cval);
+stable_read(gtmr_cntvct);
+stable_read(gtmr_cntpct);
+
static int gtmr_match(device_t, cfdata_t, void *);
static void gtmr_attach(device_t, device_t, void *);
@@ -150,6 +195,7 @@ gtmr_attach(device_t parent, device_t se
gtmr_timecounter.tc_name = device_xname(sc->sc_dev);
gtmr_timecounter.tc_frequency = sc->sc_freq;
+ gtmr_timecounter.tc_priv = sc;
tc_init(>mr_timecounter);
@@ -177,8 +223,8 @@ gtmr_init_cpu_clock(struct cpu_info *ci)
* Get now and update the compare timer.
*/
arm_isb();
- ci->ci_lastintr = gtmr_cntvct_read();
- gtmr_cntv_tval_write(sc->sc_autoinc);
+ ci->ci_lastintr = gtmr_cntvct_stable_read(sc);
+ gtmr_cntv_tval_stable_write(sc, sc->sc_autoinc);
splx(s);
KASSERT(gtmr_cntvct_read() != 0);
}
@@ -210,11 +256,11 @@ gtmr_delay(unsigned int n)
unsigned int delta = 0, usecs = 0;
arm_isb();
- uint64_t last = gtmr_cntpct_read();
+ uint64_t last = gtmr_cntpct_stable_read(sc);
while (n > usecs) {
arm_isb();
- uint64_t curr = gtmr_cntpct_read();
+ uint64_t curr = gtmr_cntpct_stable_read(sc);
if (curr < last)
delta += curr + (UINT64_MAX - last);
else
@@ -246,11 +292,11 @@ gtmr_intr(void *arg)
if ((ctl & CNTCTL_ISTATUS) == 0)
return 0;
- const uint64_t now = gtmr_cntvct_read();
+ const uint64_t now = gtmr_cntvct_stable_read(sc);
uint64_t delta = now - ci->ci_lastintr;
#ifdef DIAGNOSTIC
- const uint64_t then = gtmr_cntv_cval_read();
+ const uint64_t then = gtmr_cntv_cval_stable_read(sc);
struct gtmr_percpu * const pc = percpu_getref(sc->sc_percpu);
KASSERTMSG(then <= now, "%"PRId64, now - then);
KASSERTMSG(then + pc->pc_delta >= ci->ci_lastintr + sc->sc_autoinc,
@@ -271,7 +317,7 @@ gtmr_intr(void *arg)
} else {
delta = 0;
}
- gtmr_cntv_tval_write(sc->sc_autoinc - delta);
+ gtmr_cntv_tval_stable_write(sc, sc->sc_autoinc - delta);
ci->ci_lastintr = now;
@@ -296,6 +342,7 @@ setstatclockrate(int newhz)
static u_int
gtmr_get_timecount(struct timecounter *tc)
{
+ struct gtmr_softc * const sc = tc->tc_priv;
arm_isb(); // we want the time NOW, not some instructions later.
- return (u_int) gtmr_cntpct_read();
+ return (u_int) gtmr_cntpct_stable_read(sc);
}
Index: src/sys/arch/arm/include/armreg.h
diff -u src/sys/arch/arm/include/armreg.h:1.120 src/sys/arch/arm/include/armreg.h:1.121
--- src/sys/arch/arm/include/armreg.h:1.120 Sun Apr 1 04:35:04 2018
+++ src/sys/arch/arm/include/armreg.h Mon May 14 17:15:54 2018
@@ -1,4 +1,4 @@
-/* $NetBSD: armreg.h,v 1.120 2018/04/01 04:35:04 ryo Exp $ */
+/* $NetBSD: armreg.h,v 1.121 2018/05/14 17:15:54 joerg Exp $ */
/*
* Copyright (c) 1998, 2001 Ben Harris
@@ -969,6 +969,13 @@ gtmr_cntp_ctl_write(uint32_t val)
/*
* Counter-timer Virtual Timer TimerValue register
*/
+static inline uint32_t
+gtmr_cntv_tval_read(void)
+{
+
+ return armreg_cntv_tval_read();
+}
+
static inline void
gtmr_cntv_tval_write(uint32_t val)
{
