>but now I'm having trouble clearing the WOVF bit at startup.
The WOVF will be cleared automatically on reset. You should not have to do anything.
>Where can I find the Linux BSP code that does this? I'd like to see if they're using a trick I'm missing.
here:
https://github.com/renesas-rz/linux-3.14/blob/master/arch/arm/mach-shmobile/board-rskrza1.c#L2267
#define WTCSR 0
#define WTCNT 2
#define WRCSR 4
static void r7s72100_restart(enum reboot_mode mode, const char *cmd)
{
void *base = ioremap_nocache(0xFCFE0000, 0x10);
/* If you have board specific stuff to do, you can do it
here before you reboot */
/* NOTE: A reboot command doesn't 'sync' before this function
is called. See funciotn reboot() in kernel/reboot.c */
/* Dummy read (must read WRCSR:WOVF at least once before clearing) */
*(volatile uint8_t *)(base + WRCSR) = *(uint8_t *)(base + WRCSR);
*(volatile uint16_t *)(base + WRCSR) = 0xA500; /* Clear WOVF */
*(volatile uint16_t *)(base + WRCSR) = 0x5A5F; /* Reset Enable */
*(volatile uint16_t *)(base + WTCNT) = 0x5A00; /* Counter to 00 */
*(volatile uint16_t *)(base + WTCSR) = 0xA578; /* Start timer */
while(1); /* Wait for WDT overflow */
}
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