cobalt/clock: dovetail: abstract interface to hardware TSC

Unlike the I-pipe, Dovetail does not need to expose the underlying
timestamp counter to applications. The best equivalent to this counter
would be the common monotonic clock, expressing time as a count of
nanoseconds.

Fork the implementation accordingly between Dovetail and I-pipe
configurations, depending on which pipeline flavour was detected at
init.
Signed-off-by: Philippe Gerum <rpm@xenomai.org>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>

include/cobalt/sys/cobalt.h

@@ -134,6 +134,8 @@ void cobalt_register_tsd_hook(struct cobalt_tsd_hook *th);
 
 void cobalt_assert_nrt(void);
 
+unsigned long long cobalt_read_tsc(void);
+
 extern int __cobalt_control_bind;
 
 #ifdef __cplusplus

include/copperplate/clockobj.h

@@ -70,8 +70,6 @@ void clockobj_get_distance(struct clockobj *clkobj,
 			   const struct itimerspec *itm,
 			   struct timespec *delta);
 
-ticks_t clockobj_get_tsc(void);
-
 void clockobj_caltime_to_timeout(struct clockobj *clkobj, const struct tm *tm,
 				 unsigned long rticks, struct timespec *ts);
 
@@ -112,6 +110,7 @@ void __clockobj_ticks_to_timespec(struct clockobj *clkobj,
 #ifdef CONFIG_XENO_COBALT
 
 #include <cobalt/ticks.h>
+#include <cobalt/sys/cobalt.h>
 
 /*
  * The Cobalt core exclusively deals with aperiodic timings, so a
@@ -121,6 +120,13 @@ void __clockobj_ticks_to_timespec(struct clockobj *clkobj,
  * equivalent to Copperplate TSC units, and Copperplate ticks are
  * periods of the reference clockobj which Cobalt does not know about.
  */
+
+static inline ticks_t clockobj_get_tsc(void)
+{
+	/* Guaranteed to be the source of CLOCK_COPPERPLATE. */
+	return cobalt_read_tsc();
+}
+
 static inline sticks_t clockobj_ns_to_tsc(sticks_t ns)
 {
 	return cobalt_ns_to_ticks(ns);
@@ -142,6 +148,8 @@ void clockobj_ns_to_timespec(ticks_t ns, struct timespec *ts)
 
 #else /* CONFIG_XENO_MERCURY */
 
+ticks_t clockobj_get_tsc(void);
+
 static inline sticks_t clockobj_ns_to_tsc(sticks_t ns)
 {
 	return ns;

lib/cobalt/arch/arm/include/asm/xenomai/tsc.h

@@ -40,7 +40,7 @@ struct __xn_full_tscinfo {
 extern struct __xn_full_tscinfo __xn_tscinfo;
 
 static inline __attribute__((always_inline))
-unsigned long long cobalt_read_tsc(void)
+unsigned long long cobalt_read_legacy_tsc(void)
 {
 	return __xn_tscinfo.kuser_tsc_get(__xn_tscinfo.kinfo.counter);
 }

lib/cobalt/arch/arm64/include/asm/xenomai/tsc.h

@@ -46,7 +46,7 @@ static inline uint64_t get_counter(void)
 }
 
 static inline __attribute__((always_inline))
-unsigned long long cobalt_read_tsc(void)
+unsigned long long cobalt_read_legacy_tsc(void)
 {
 	return get_counter();
 }

lib/cobalt/arch/powerpc/include/asm/xenomai/tsc.h

@@ -18,7 +18,7 @@
 #ifndef _LIB_COBALT_POWERPC_TSC_H
 #define _LIB_COBALT_POWERPC_TSC_H
 
-static inline unsigned long long cobalt_read_tsc(void)
+static inline unsigned long long cobalt_read_legacy_tsc(void)
 {
 	union {
 		unsigned long long t;

lib/cobalt/arch/x86/include/asm/xenomai/tsc.h

@@ -19,7 +19,7 @@
 #ifndef _LIB_COBALT_X86_TSC_H
 #define _LIB_COBALT_X86_TSC_H
 
-static inline unsigned long long cobalt_read_tsc(void)
+static inline unsigned long long cobalt_read_legacy_tsc(void)
 {
 #ifdef __i386__
 	unsigned long long t;

lib/cobalt/clock.c

@@ -136,7 +136,7 @@ static int __do_clock_host_realtime(struct timespec *ts)
 	 * mechanism in the kernel.
 	 */
 	unsynced_read_block(&tmp, &hostrt_data->lock) {
-		now = cobalt_read_tsc();
+		now = cobalt_read_legacy_tsc();
 		base = hostrt_data->cycle_last;
 		mask = hostrt_data->mask;
 		mult = hostrt_data->mult;
@@ -175,12 +175,12 @@ static int gettime_via_tsc(clockid_t clock_id, struct timespec *tp)
 		break;
 	case CLOCK_MONOTONIC:
 	case CLOCK_MONOTONIC_RAW:
-		ns = cobalt_ticks_to_ns(cobalt_read_tsc());
+		ns = cobalt_ticks_to_ns(cobalt_read_legacy_tsc());
 		tp->tv_sec = cobalt_divrem_billion(ns, &rem);
 		tp->tv_nsec = rem;
 		return 0;
 	case CLOCK_REALTIME:
-		ns = cobalt_ticks_to_ns(cobalt_read_tsc());
+		ns = cobalt_ticks_to_ns(cobalt_read_legacy_tsc());
 		ns += cobalt_vdso->wallclock_offset;
 		tp->tv_sec = cobalt_divrem_billion(ns, &rem);
 		tp->tv_nsec = rem;

lib/cobalt/internal.c

@@ -31,6 +31,8 @@
 #include <stdarg.h>
 #include <pthread.h>
 #include <asm/xenomai/syscall.h>
+#include <asm/xenomai/tsc.h>
+#include <cobalt/ticks.h>
 #include <cobalt/sys/cobalt.h>
 #include "internal.h"
 
@@ -553,7 +555,7 @@ int cobalt_xlate_schedparam(int policy,
 
 	if (priority < 0)
 		priority = -priority;
-	
+
 	memset(param, 0, sizeof(*param));
 	param->sched_priority = priority;
 
@@ -566,6 +568,18 @@ void cobalt_assert_nrt(void)
 		pthread_kill(pthread_self(), SIGDEBUG);
 }
 
+unsigned long long cobalt_read_tsc(void)
+{
+	struct timespec ts;
+
+	if (cobalt_use_legacy_tsc())
+		return cobalt_read_legacy_tsc();
+
+	__cobalt_vdso_gettime(CLOCK_MONOTONIC, &ts);
+
+	return ts.tv_sec * 1000000000ULL + ts.tv_nsec;
+}
+
 unsigned int cobalt_features;
 
 void cobalt_features_init(struct cobalt_featinfo *f)
@@ -574,4 +588,4 @@ void cobalt_features_init(struct cobalt_featinfo *f)
 
 	/* Trigger arch specific feature initialization */
 	cobalt_arch_check_features(f);
-}
\ No newline at end of file
+}

lib/copperplate/clockobj.c

@@ -229,22 +229,12 @@ int clockobj_set_resolution(struct clockobj *clkobj, unsigned int resolution_ns)
 #ifdef CONFIG_XENO_COBALT
 
 #include <cobalt/arith.h>
-#include <asm/xenomai/tsc.h>
+#include <cobalt/sys/cobalt.h>
 
 #ifdef CONFIG_XENO_COPPERPLATE_CLOCK_RESTRICTED
 #error "restricted CLOCK_COPPERPLATE not available"
 #endif
 
-/*
- * NOTE: we can't inline this routine, as we don't want to expose
- * lib/cobalt/arch/.../include/asm/xenomai/tsc.h.
- */
-ticks_t clockobj_get_tsc(void)
-{
-	/* Guaranteed to be the source of CLOCK_COPPERPLATE. */
-	return cobalt_read_tsc();
-}
-
 ticks_t clockobj_get_time(struct clockobj *clkobj)
 {
 	ticks_t ns = cobalt_ticks_to_ns_rounded(cobalt_read_tsc());

testsuite/smokey/tsc/tsc.c

@@ -30,7 +30,7 @@
 
 #include <smokey/smokey.h>
 
-#include <asm/xenomai/tsc.h>
+#include <cobalt/sys/cobalt.h>
 
 #define DURATION 10000000