Allow using ARM cycle counter as timing

Signed-off-by: falkTX <[email protected]>

Author: falkTX

common/JackServerGlobals.cpp

@@ -204,11 +204,7 @@ bool JackServerGlobals::Init()
                     if (tolower (optarg[0]) == 'h') {
                         clock_source = JACK_TIMER_HPET;
                     } else if (tolower (optarg[0]) == 'c') {
-                        /* For backwards compatibility with scripts, allow
-                         * the user to request the cycle clock on the
-                         * command line, but use the system clock instead
-                         */
-                        clock_source = JACK_TIMER_SYSTEM_CLOCK;
+                        clock_source = JACK_TIMER_CYCLE_COUNTER;
                     } else if (tolower (optarg[0]) == 's') {
                         clock_source = JACK_TIMER_SYSTEM_CLOCK;
                     } else {

common/JackTypes.h

@@ -39,6 +39,7 @@ typedef uint16_t jack_int_t;  // Internal type for ports and refnum
 
 typedef enum {
 	JACK_TIMER_SYSTEM_CLOCK,
+	JACK_TIMER_CYCLE_COUNTER,
 	JACK_TIMER_HPET,
 } jack_timer_type_t;
 

common/Jackdmp.cpp

@@ -210,7 +210,7 @@ static void usage(FILE* file, jackctl_server_t *server, bool full = true)
             "               [ --internal-session-file OR -C internal-session-file ]\n"
             "               [ --verbose OR -v ]\n"
 #ifdef __linux__
-            "               [ --clocksource OR -c [ h(pet) | s(ystem) ]\n"
+            "               [ --clocksource OR -c [ c(ycle) | h(pet) | s(ystem) ]\n"
 #endif
             "               [ --autoconnect OR -a <modechar>]\n");
 
@@ -354,11 +354,7 @@ int main(int argc, char** argv)
                         value.ui = JACK_TIMER_HPET;
                         jackctl_parameter_set_value(param, &value);
                     } else if (tolower (optarg[0]) == 'c') {
-                        /* For backwards compatibility with scripts, allow
-                         * the user to request the cycle clock on the
-                         * command line, but use the system clock instead
-                         */
-                        value.ui = JACK_TIMER_SYSTEM_CLOCK;
+                        value.ui = JACK_TIMER_CYCLE_COUNTER;
                         jackctl_parameter_set_value(param, &value);
                     } else if (tolower (optarg[0]) == 's') {
                         value.ui = JACK_TIMER_SYSTEM_CLOCK;

linux/JackLinuxTime.c

@@ -59,6 +59,34 @@ static uint64_t hpet_wrap;
 static hpet_counter_t hpet_previous = 0;
 #endif /* defined(__gnu_linux__) && (__i386__ || __x86_64__) */
 
+#if defined(__ARM_ARCH_8A) && !defined(_MOD_DEVICE_DUOX)
+static uint64_t _cntfrq_mhz = 0;
+static void _cntfrq_mhz_init() {
+	asm volatile("mrs %0, CNTFRQ_EL0" : "=r"(_cntfrq_mhz));
+	_cntfrq_mhz /= 1000000;
+};
+#endif
+
+static jack_time_t jack_get_microseconds_from_cycles (void)
+{
+#if defined(_MOD_DEVICE_DUO)
+	uint32_t r;
+	asm volatile("mrc p15, 0, %0, c9, c13, 0\t\n" : "=r"(r));
+	return (((uint64_t)r) << 6) / 912; // 912 is the hardcoded MOD Duo CPU frequency
+#elif defined(_MOD_DEVICE_DUOX)
+	uint64_t r;
+	asm volatile("mrs %0, CNTVCT_EL0" : "=r"(r));
+	return r * 0.12;
+#elif defined(__ARM_ARCH_8A)
+	uint64_t r;
+	asm volatile("mrs %0, CNTVCT_EL0" : "=r"(r));
+	return r / _cntfrq_mhz;
+#else
+	#warning Cycle counter implementation missing
+	return 0;
+#endif
+}
+
 #ifdef HPET_SUPPORT
 
 static int jack_hpet_init ()
@@ -175,6 +203,13 @@ void SetClockSource(jack_timer_type_t source)
 
 	switch (source)
 	{
+        case JACK_TIMER_CYCLE_COUNTER:
+#if defined(__ARM_ARCH_8A) && !defined(_MOD_DEVICE_DUOX)
+            _cntfrq_mhz_init();
+#endif
+            _jack_get_microseconds = jack_get_microseconds_from_cycles;
+            break;
+
         case JACK_TIMER_HPET:
             if (jack_hpet_init () == 0) {
                 _jack_get_microseconds = jack_get_microseconds_from_hpet;
@@ -193,6 +228,8 @@ void SetClockSource(jack_timer_type_t source)
 const char* ClockSourceName(jack_timer_type_t source)
 {
 	switch (source) {
+        case JACK_TIMER_CYCLE_COUNTER:
+            return "cycle counter";
         case JACK_TIMER_HPET:
             return "hpet";
         case JACK_TIMER_SYSTEM_CLOCK: