sparc: Rework CPU counter support

Rework CPU counter support to enable use of the GR740 up-counter via
%asr22 and %asr23.

4 files changed, 88 insertions, 26 deletions

diff --git a/cpukit/score/cpu/sparc/Makefile.am b/cpukit/score/cpu/sparc/Makefile.am
index edebbb6041..11b5d11d7f 100644
--- a/cpukit/score/cpu/sparc/Makefile.am
+++ b/cpukit/score/cpu/sparc/Makefile.am
@@ -14,6 +14,7 @@ libscorecpu_a_SOURCES = cpu.c cpu_asm.S
 libscorecpu_a_SOURCES += sparc-context-volatile-clobber.S
 libscorecpu_a_SOURCES += sparc-context-validate.S
 libscorecpu_a_SOURCES += sparc-counter.c
+libscorecpu_a_SOURCES += sparc-counter-asm.S
 libscorecpu_a_CPPFLAGS = $(AM_CPPFLAGS)
 
 include $(srcdir)/preinstall.am
diff --git a/cpukit/score/cpu/sparc/rtems/score/cpu.h b/cpukit/score/cpu/sparc/rtems/score/cpu.h
index ea90e36752..c87618db85 100644
--- a/cpukit/score/cpu/sparc/rtems/score/cpu.h
+++ b/cpukit/score/cpu/sparc/rtems/score/cpu.h
@@ -1304,6 +1304,8 @@ static inline uint32_t CPU_swap_u32(
 
 typedef uint32_t CPU_Counter_ticks;
 
+typedef CPU_Counter_ticks ( *SPARC_Counter_read )( void );
+
 typedef CPU_Counter_ticks (*SPARC_Counter_difference)(
   CPU_Counter_ticks second,
   CPU_Counter_ticks first
@@ -1311,46 +1313,57 @@ typedef CPU_Counter_ticks (*SPARC_Counter_difference)(
 
 /*
  * The SPARC processors supported by RTEMS have no built-in CPU counter
- * support.  We have to use some hardware counter module for this purpose.  The
- * BSP must provide a 32-bit register which contains the current CPU counter
- * value and a function for the difference calculation.  It can use for example
- * the GPTIMER instance used for the clock driver.
+ * support.  We have to use some hardware counter module for this purpose, for
+ * example the GPTIMER instance used by the clock driver.  The BSP must provide
+ * an implementation of the CPU counter read and difference functions.  This
+ * allows the use of dynamic hardware enumeration.
  */
 typedef struct {
-  volatile const CPU_Counter_ticks *counter_register;
-  SPARC_Counter_difference counter_difference;
+  SPARC_Counter_read                counter_read;
+  SPARC_Counter_difference          counter_difference;
+  volatile const CPU_Counter_ticks *counter_address;
 } SPARC_Counter;
 
 extern SPARC_Counter _SPARC_Counter;
 
+CPU_Counter_ticks _SPARC_Counter_read_address( void );
+
+CPU_Counter_ticks _SPARC_Counter_read_asr23( void );
+
+CPU_Counter_ticks _SPARC_Counter_difference_normal(
+  CPU_Counter_ticks second,
+  CPU_Counter_ticks first
+);
+
+CPU_Counter_ticks _SPARC_Counter_difference_clock_period(
+  CPU_Counter_ticks second,
+  CPU_Counter_ticks first
+);
+
 /*
  * Returns always a value of one regardless of the parameters.  This prevents
  * an infinite loop in rtems_counter_delay_ticks().  Its only a reasonably safe
  * default.
  */
-CPU_Counter_ticks _SPARC_Counter_difference_default(
+CPU_Counter_ticks _SPARC_Counter_difference_one(
   CPU_Counter_ticks second,
   CPU_Counter_ticks first
 );
 
-static inline bool _SPARC_Counter_is_default( void )
-{
-  return _SPARC_Counter.counter_difference
-    == _SPARC_Counter_difference_default;
-}
-
 static inline void _SPARC_Counter_initialize(
-  volatile const CPU_Counter_ticks *counter_register,
-  SPARC_Counter_difference counter_difference
+  SPARC_Counter_read                counter_read,
+  SPARC_Counter_difference          counter_difference,
+  volatile const CPU_Counter_ticks *counter_address
 )
 {
-  _SPARC_Counter.counter_register = counter_register;
+  _SPARC_Counter.counter_read = counter_read;
   _SPARC_Counter.counter_difference = counter_difference;
+  _SPARC_Counter.counter_address = counter_address;
 }
 
 static inline CPU_Counter_ticks _CPU_Counter_read( void )
 {
-  return *_SPARC_Counter.counter_register;
+  return ( *_SPARC_Counter.counter_read )();
 }
 
 static inline CPU_Counter_ticks _CPU_Counter_difference(
@@ -1358,7 +1371,7 @@ static inline CPU_Counter_ticks _CPU_Counter_difference(
   CPU_Counter_ticks first
 )
 {
-  return (*_SPARC_Counter.counter_difference)( second, first );
+  return ( *_SPARC_Counter.counter_difference )( second, first );
 }
 
 #endif /* ASM */
diff --git a/cpukit/score/cpu/sparc/sparc-counter-asm.S b/cpukit/score/cpu/sparc/sparc-counter-asm.S
new file mode 100644
index 0000000000..8ed079f48b
--- /dev/null
+++ b/cpukit/score/cpu/sparc/sparc-counter-asm.S
@@ -0,0 +1,34 @@
+/*
+ * Copyright (c) 2016 embedded brains GmbH.  All rights reserved.
+ *
+ *  embedded brains GmbH
+ *  Dornierstr. 4
+ *  82178 Puchheim
+ *  Germany
+ *  <rtems@embedded-brains.de>
+ *
+ * The license and distribution terms for this file may be
+ * found in the file LICENSE in this distribution or at
+ * http://www.rtems.org/license/LICENSE.
+ */
+
+#if HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <rtems/asm.h>
+
+	.section	".text"
+	.align	4
+
+	PUBLIC(_SPARC_Counter_read_address)
+SYM(_SPARC_Counter_read_address):
+	sethi	%hi(_SPARC_Counter + 8), %o0
+	ld	[%o0 + %lo(_SPARC_Counter + 8)], %o0
+	jmp	%o7 + 8
+	 ld	[%o0], %o0
+
+	PUBLIC(_SPARC_Counter_read_asr23)
+SYM(_SPARC_Counter_read_asr23):
+	jmp	%o7 + 8
+	 mov	%asr23, %o0
diff --git a/cpukit/score/cpu/sparc/sparc-counter.c b/cpukit/score/cpu/sparc/sparc-counter.c
index d254503651..658a47c37e 100644
--- a/cpukit/score/cpu/sparc/sparc-counter.c
+++ b/cpukit/score/cpu/sparc/sparc-counter.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014 embedded brains GmbH.  All rights reserved.
+ * Copyright (c) 2014, 2016 embedded brains GmbH.  All rights reserved.
  *
  *  embedded brains GmbH
  *  Dornierstr. 4
@@ -17,18 +17,32 @@
 #endif
 
 #include <rtems/score/cpu.h>
+#include <rtems/config.h>
 
-static CPU_Counter_ticks _SPARC_Counter_register_dummy;
+CPU_Counter_ticks _SPARC_Counter_difference_normal(
+  CPU_Counter_ticks second,
+  CPU_Counter_ticks first
+)
+{
+  return second - first;
+}
 
-CPU_Counter_ticks _SPARC_Counter_difference_default(
+CPU_Counter_ticks _SPARC_Counter_difference_clock_period(
   CPU_Counter_ticks second,
   CPU_Counter_ticks first
 )
 {
-  return 1;
+  CPU_Counter_ticks period;
+
+  period = rtems_configuration_get_microseconds_per_tick();
+
+  return ( first + period - second ) % period;
 }
 
-SPARC_Counter _SPARC_Counter = {
-  .counter_register = &_SPARC_Counter_register_dummy,
-  .counter_difference = _SPARC_Counter_difference_default
-};
+CPU_Counter_ticks _SPARC_Counter_difference_one(
+  CPU_Counter_ticks second,
+  CPU_Counter_ticks first
+)
+{
+  return 1;
+}