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ti: wdt: omap: Disable watchdog timer before performing initialization

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The OMAP WDT IP block requires to be stopped before any write to its
registers is performed.

This problem has been thoroughly described in Linux kernel:

"watchdog: omap: assert the counter being stopped before reprogramming:
SHA1: 530c11d432727c697629ad5f9d00ee8e2864d453

Signed-off-by: Lukasz Majewski <lukma@denx.de>
Reviewed-by: Tom Rini <trini@konsulko.com>
This commit is contained in:
Lukasz Majewski 2017-02-19 23:24:38 +01:00 committed by Tom Rini
parent 737af81927
commit b633b9c8fe
1 changed files with 22 additions and 15 deletions
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37
drivers/watchdog/omap_wdt.c
View File

@ -81,10 +81,32 @@ static int omap_wdt_set_timeout(unsigned int timeout)
return 0; return 0;
} }
void hw_watchdog_disable(void)
{
struct wd_timer *wdt = (struct wd_timer *)WDT_BASE;
/*
* Disable watchdog
*/
writel(0xAAAA, &wdt->wdtwspr);
while (readl(&wdt->wdtwwps) != 0x0)
;
writel(0x5555, &wdt->wdtwspr);
while (readl(&wdt->wdtwwps) != 0x0)
;
}
void hw_watchdog_init(void) void hw_watchdog_init(void)
{ {
struct wd_timer *wdt = (struct wd_timer *)WDT_BASE; struct wd_timer *wdt = (struct wd_timer *)WDT_BASE;
/*
* Make sure the watchdog is disabled. This is unfortunately required
* because writing to various registers with the watchdog running has no
* effect.
*/
hw_watchdog_disable();
/* initialize prescaler */ /* initialize prescaler */
while (readl(&wdt->wdtwwps) & WDT_WWPS_PEND_WCLR) while (readl(&wdt->wdtwwps) & WDT_WWPS_PEND_WCLR)
; ;
@ -104,18 +126,3 @@ void hw_watchdog_init(void)
while ((readl(&wdt->wdtwwps)) & WDT_WWPS_PEND_WSPR) while ((readl(&wdt->wdtwwps)) & WDT_WWPS_PEND_WSPR)
; ;
} }
void hw_watchdog_disable(void)
{
struct wd_timer *wdt = (struct wd_timer *)WDT_BASE;
/*
* Disable watchdog
*/
writel(0xAAAA, &wdt->wdtwspr);
while (readl(&wdt->wdtwwps) != 0x0)
;
writel(0x5555, &wdt->wdtwspr);
while (readl(&wdt->wdtwwps) != 0x0)
;
}