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* shared/clock/clock.c: Standard decrementer exception is now more

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robust against erroneous external exception disable times.
This commit is contained in:
Thomas Doerfler
2009-03-05 13:45:06 +00:00
parent eb7ee96a75
commit 21ae805dc1
2 changed files with 39 additions and 27 deletions
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5
c/src/lib/libbsp/powerpc/ChangeLog
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@@ -1,3 +1,8 @@
2009-03-05 Sebastian Huber <sebastian.huber@embedded-brains.de>
* shared/clock/clock.c: Standard decrementer exception is now more
robust against erroneous external exception disable times.
2009-02-27 Joel Sherrill <joel.sherrill@OARcorp.com> 2009-02-27 Joel Sherrill <joel.sherrill@OARcorp.com>
* shared/startup/bspgetworkarea.c: Add check to determine if current * shared/startup/bspgetworkarea.c: Add check to determine if current

47
c/src/lib/libbsp/powerpc/shared/clock/clock.c
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@@ -7,15 +7,16 @@
*/ */
/* /*
* Copyright (c) 2008 * Copyright (c) 2008, 2009
* Embedded Brains GmbH * Embedded Brains GmbH
* Obere Lagerstr. 30 * Obere Lagerstr. 30
* D-82178 Puchheim * D-82178 Puchheim
* Germany * Germany
* rtems@embedded-brains.de * rtems@embedded-brains.de
* *
* The license and distribution terms for this file may be found in the file * The license and distribution terms for this file may be
* LICENSE in this distribution or at http://www.rtems.com/license/LICENSE. * found in the file LICENSE in this distribution or at
* http://www.rtems.com/license/LICENSE.
*/ */
#include <rtems.h> #include <rtems.h>
@@ -57,23 +58,13 @@ static void (*ppc_clock_tick)(void) = ppc_clock_no_tick;
static int ppc_clock_exception_handler( BSP_Exception_frame *frame, unsigned number) static int ppc_clock_exception_handler( BSP_Exception_frame *frame, unsigned number)
{ {
uint32_t reg1; uint32_t delta = ppc_clock_decrementer_value;
uint32_t reg2; uint32_t next = ppc_clock_next_time_base;
uint32_t reg3; uint32_t dec = 0;
uint32_t msr; uint32_t now = 0;
uint32_t msr = 0;
/* Set new decrementer value according to a reference time base */
asm volatile (
"lwz %0, ppc_clock_next_time_base@sdarel(13);"
"lwz %1, ppc_clock_decrementer_value@sdarel(13);"
"mftb %2;"
"add %0, %0, %1;"
"subf %1, %2, %0;"
"stw %0, ppc_clock_next_time_base@sdarel(13);"
"mtdec %1;"
: "=r" (reg1), "=r" (reg2), "=r" (reg3)
);
do {
/* Increment clock ticks */ /* Increment clock ticks */
Clock_driver_ticks += 1; Clock_driver_ticks += 1;
@@ -86,6 +77,22 @@ static int ppc_clock_exception_handler( BSP_Exception_frame *frame, unsigned num
/* Restore machine state */ /* Restore machine state */
ppc_external_exceptions_disable( msr); ppc_external_exceptions_disable( msr);
/* Next time base */
next += delta;
/* Current time */
now = ppc_time_base();
/* New decrementer value */
dec = next - now;
} while (dec > delta);
/* Set decrementer */
ppc_set_decrementer_register( dec);
/* Expected next time base */
ppc_clock_next_time_base = next;
return 0; return 0;
} }
@@ -201,7 +208,7 @@ rtems_device_driver Clock_initialize( rtems_device_major_number major, rtems_dev
/* Check decrementer value */ /* Check decrementer value */
if (ppc_clock_decrementer_value == 0) { if (ppc_clock_decrementer_value == 0) {
ppc_clock_decrementer_value = PPC_CLOCK_DECREMENTER_MAX; ppc_clock_decrementer_value = PPC_CLOCK_DECREMENTER_MAX;
RTEMS_SYSLOG_ERROR( "Decrementer value would be zero, will be set to maximum value instead\n"); RTEMS_SYSLOG_ERROR( "decrementer value would be zero, will be set to maximum value instead\n");
} }
/* Set the nanoseconds since last tick handler */ /* Set the nanoseconds since last tick handler */