2008-12-03 Joel Sherrill <joel.sherrill@OARcorp.com>

Michael South <msouth@msouth.org>

	PR 1344/bsps
	* configure.ac, clock/ckinit.c, timer/timer.c: Add use of TSC for
	nanoseconds granularity. i8254 is very slow on some systems. TSC use
	is auto-detected by default.

c/src/lib/libbsp/i386/pc386/ChangeLog

@@ -1,3 +1,11 @@
+2008-12-03	Joel Sherrill <joel.sherrill@OARcorp.com>
+		Michael South <msouth@msouth.org>
+
+	PR 1344/bsps
+	* configure.ac, clock/ckinit.c, timer/timer.c: Add use of TSC for
+	nanoseconds granularity. i8254 is very slow on some systems. TSC use
+	is auto-detected by default.
+
 2008-12-02	Joel Sherrill <joel.sherrill@oarcorp.com>
 
 	* startup/bspgetworkarea.c: Remove debug prints.

c/src/lib/libbsp/i386/pc386/configure.ac

@@ -46,6 +46,41 @@ RTEMS_BSPOPTS_HELP([BSP_PRESS_KEY_FOR_RESET],
  before rebooting the PC.  This is useful for unattended PC deployments
 ])
 
+RTEMS_BSPOPTS_SET([CLOCK_DRIVER_USE_TSC],[*],[0])
+RTEMS_BSPOPTS_HELP([CLOCK_DRIVER_USE_TSC],
+[If enabled, the clock driver will use the TSC register available
+ with Pentium-class CPUs to report close to nanosecond-accuracy
+ clock times.
+ Enable it, if:
+ - you have nanosecond timing enabled (you do NOT have
+   USE_TICKS_FOR_CPU_USAGE_STATISTICS enabled)
+ - you do NOT have CLOCK_DRIVER_USE_8254 enabled (use one, the other,
+   or neither)
+ - you have a Pentium which supports TSC (all Intels, and probably
+   all or most clones)
+ - you do not have a variable-speed CPU clock. Note that some
+   motherboard BIOS will automatically vary clock speed for thermal
+   control. Note also, however, that really new Pentium-class chips
+   from Intel and AMD will maintain a constant-rate TSC regardless.
+])
+
+RTEMS_BSPOPTS_SET([CLOCK_DRIVER_USE_8254],[*],[0])
+RTEMS_BSPOPTS_HELP([CLOCK_DRIVER_USE_8254],
+[If enabled, the clock driver will use the good old 8254 chip
+ to report microsecond-accuracy clock times.
+ Enable it, if:
+ - you have nanosecond timing enabled (you do NOT have
+   USE_TICKS_FOR_CPU_USAGE_STATISTICS enabled)
+ - you do NOT have CLOCK_DRIVER_USE_TSC enabled (use one, the other,
+   or neither)
+ - you do not mind adding roughly 5 microseconds to each context switch.
+])
+
+if test X${CLOCK_DRIVER_USE_TSC} = X1 -a X${CLOCK_DRIVER_USE_8254} = X1 ; then
+  AC_MSG_ERROR([pc386 both TSC and 8254 specified for clock driver])
+fi
+
+#define CLOCK_DRIVER_USE_8254 $CLOCK_DRIVER_USE_8254
 ## if this is an i386, does gas have good code16 support?
 RTEMS_I386_GAS_CODE16
 AM_CONDITIONAL(RTEMS_GAS_CODE16,[test "$RTEMS_GAS_CODE16" = "yes"])

c/src/lib/libbsp/i386/pc386/timer/timer.c

@@ -42,6 +42,7 @@
 
 #include <bsp.h>
 #include <bsp/irq.h>
+#include <libcpu/cpuModel.h>
 
 /*-------------------------------------------------------------------------+
 | Constants
@@ -59,18 +60,18 @@
 | Global Variables
 +--------------------------------------------------------------------------*/
 volatile uint32_t         Ttimer_val;
-bool    	  benchmark_timer_find_average_overhead = true;
+bool    	          benchmark_timer_find_average_overhead = true;
 volatile unsigned int     fastLoop1ms, slowLoop1ms;
-void (*benchmark_timer_initialize_function)(void) = 0;
+
+void     (*benchmark_timer_initialize_function)(void) = 0;
 uint32_t (*benchmark_timer_read_function)(void) = 0;
-void (*Timer_exit_function)(void) = 0;
+void     (*Timer_exit_function)(void) = 0;
 
 /*-------------------------------------------------------------------------+
 | External Prototypes
 +--------------------------------------------------------------------------*/
 extern void timerisr(void);
        /* timer (int 08h) Interrupt Service Routine (defined in 'timerisr.s') */
-extern int x86_capability;
 
 /*
  * forward declarations
@@ -82,22 +83,6 @@ void Timer_exit(void);
 | Pentium optimized timer handling.
 +--------------------------------------------------------------------------*/
 
-/*-------------------------------------------------------------------------+
-|         Function: rdtsc
-|      Description: Read the value of PENTIUM on-chip cycle counter.
-| Global Variables: None.
-|        Arguments: None.
-|          Returns: Value of PENTIUM on-chip cycle counter.
-+--------------------------------------------------------------------------*/
-static inline unsigned long long
-rdtsc(void)
-{
-  /* Return the value of the on-chip cycle counter. */
-  unsigned long long result;
-  asm volatile(".byte 0x0F, 0x31" : "=A" (result));
-  return result;
-} /* rdtsc */
-
 /*-------------------------------------------------------------------------+
 |         Function: Timer_exit
 |      Description: Timer cleanup routine at RTEMS exit. NOTE: This routine is
@@ -288,7 +273,7 @@ benchmark_timer_initialize(void)
     static bool First = true;
 
     if (First) {
-        if (x86_capability & (1 << 4) ) {
+        if (x86_has_tsc()) {
 #if defined(DEBUG)
             printk("TSC: timer initialization\n");
 #endif /* DEBUG */