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Comments and style(9) only, no functional changes.

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This commit is contained in:
ian 2013-11-03 22:55:33 +00:00
parent 6de43e64b8
commit 07ca1c7f05
1 changed files with 15 additions and 16 deletions
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31
sys/arm/freescale/imx/imx_machdep.c
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@ -158,34 +158,33 @@ bus_dma_get_range_nb(void)
return (0); return (0);
} }
/*
* This code which manipulates the watchdog hardware is here to implement
* cpu_reset() because the watchdog is the only way for software to reset the
* chip. Why here and not in imx_wdog.c? Because there's no requirement that
* the watchdog driver be compiled in, but it's nice to be able to reboot even
* if it's not.
*/
void void
imx_wdog_cpu_reset(vm_offset_t wdcr_physaddr) imx_wdog_cpu_reset(vm_offset_t wdcr_physaddr)
{ {
const struct pmap_devmap *pd;
volatile uint16_t * pcr;
/* /*
* This code which manipulates the watchdog hardware is here to * The deceptively simple write of WDOG_CR_WDE enables the watchdog,
* implement cpu_reset() because the watchdog is the only way for * sets the timeout to its minimum value (half a second), and also
* software to reset the chip. Why here and not in imx_wdog.c? Because * clears the SRS bit which results in the SFTW (software-requested
* there's no requirement that the watchdog driver be compiled in, but * reset) bit being set in the watchdog status register after the reset.
* it's nice to be able to reboot even if it's not. * This is how software can distinguish a reset from a wdog timeout.
*/ */
volatile uint16_t * pcr;
const struct pmap_devmap *pd;
if ((pd = pmap_devmap_find_pa(wdcr_physaddr, 2)) == NULL) { if ((pd = pmap_devmap_find_pa(wdcr_physaddr, 2)) == NULL) {
printf("cpu_reset() can't find its control register... locking up now."); printf("cpu_reset() can't find its control register... locking up now.");
} else { } else {
pcr = (uint16_t *)(pd->pd_va + (wdcr_physaddr - pd->pd_pa)); pcr = (uint16_t *)(pd->pd_va + (wdcr_physaddr - pd->pd_pa));
/*
* This deceptively simple write enables the watchdog, sets the timeout
* to its minimum value (half a second), and also clears the SRS bit
* which results in the SFTW (software-requested reset) bit being set in
* the watchdog status register after the reset. This is how software
* can distinguish a requested reset from a wdog timeout.
*/
*pcr = WDOG_CR_WDE; *pcr = WDOG_CR_WDE;
} }
while (1) for (;;)
continue; continue;
} }