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beagle bsp: disable watchdog on am335x

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On recent u-boots, the watchdog is turned on / left enabled. The
Beaglebone Black rev. C ships with such a u-boot internally so any
application booting from it must disable the watchdog.

Therefore this change is needed to boot an RTEMS app out-of-the-box
on a BBB Rev C - otherwise the user button must be held during boot
(to bypass the stock uboot) or the internal uboot must be updated. To
allow for a better out-of-the-box experience, we just turn off the
watchdog.
This commit is contained in:
Ben Gras
2014-12-04 18:21:11 +01:00
parent 4251b88736
commit 13d9029453
2 changed files with 15 additions and 0 deletions
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9
c/src/lib/libbsp/arm/beagle/clock.c
View File

@@ -251,6 +251,15 @@ beagle_clock_initialize(void)
OMAP3_TCLR_OVF_TRG | OMAP3_TCLR_AR | OMAP3_TCLR_ST); OMAP3_TCLR_OVF_TRG | OMAP3_TCLR_AR | OMAP3_TCLR_ST);
/* also initilize the free runnning timer */ /* also initilize the free runnning timer */
omap3_frclock_init(); omap3_frclock_init();
#if IS_AM335X
/* Disable AM335X watchdog */
mmio_write(AM335X_WDT_BASE+AM335X_WDT_WSPR, 0xAAAA);
while(mmio_read(AM335X_WDT_BASE+AM335X_WDT_WWPS) != 0) ;
mmio_write(AM335X_WDT_BASE+AM335X_WDT_WSPR, 0x5555);
while(mmio_read(AM335X_WDT_BASE+AM335X_WDT_WWPS) != 0) ;
#endif
} }
static void beagle_clock_at_tick(void) static void beagle_clock_at_tick(void)

6
c/src/lib/libcpu/arm/shared/include/am335x.h
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@@ -274,3 +274,9 @@
/* Control posted mode and functional SW reset */ /* Control posted mode and functional SW reset */
#define AM335X_TIMER_TCAR2 0x058 #define AM335X_TIMER_TCAR2 0x058
/* Second captured value of counter register */ /* Second captured value of counter register */
#define AM335X_WDT_BASE 0x44E35000
/* Watchdog timer */
#define AM335X_WDT_WWPS 0x34
/* Command posted status */
#define AM335X_WDT_WSPR 0x48
/* Activate/deactivate sequence */