The AM625 RTC has an erratum which requires an early fixup to make the RTC work under Linux. Apply the fixup. The code is based on the corresponding U-Boot code. Signed-off-by: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx> --- arch/arm/mach-k3/r5.c | 42 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 42 insertions(+) diff --git a/arch/arm/mach-k3/r5.c b/arch/arm/mach-k3/r5.c index 6667c0d28b..dcbdd8a698 100644 --- a/arch/arm/mach-k3/r5.c +++ b/arch/arm/mach-k3/r5.c @@ -17,6 +17,46 @@ #include <bootsource.h> #include <linux/usb/gadget-multi.h> +#define RTC_BASE_ADDRESS 0x2b1f0000 +#define K3RTC_KICK0_UNLOCK_VALUE 0x83e70b13 +#define K3RTC_KICK1_UNLOCK_VALUE 0x95a4f1e0 +#define REG_K3RTC_S_CNT_LSW 0x18 +#define REG_K3RTC_KICK0 0x70 +#define REG_K3RTC_KICK1 0x74 + +/* + * RTC Erratum i2327 Workaround for Silicon Revision 1 + * + * Due to a bug in initial synchronization out of cold power on, + * IRQ status can get locked infinitely if we do not unlock RTC + * + * This workaround *must* be applied within 1 second of power on, + * So, this is closest point to be able to guarantee the max + * timing. + * + * https://www.ti.com/lit/er/sprz487c/sprz487c.pdf + */ +static void rtc_erratumi2327_init(void) +{ + void __iomem *rtc_base = IOMEM(RTC_BASE_ADDRESS); + u32 counter; + + /* + * If counter has gone past 1, nothing we can do, leave + * system locked! This is the only way we know if RTC + * can be used for all practical purposes. + */ + counter = readl(rtc_base + REG_K3RTC_S_CNT_LSW); + if (counter > 1) + return; + /* + * Need to set this up at the very start + * MUST BE DONE under 1 second of boot. + */ + writel(K3RTC_KICK0_UNLOCK_VALUE, rtc_base + REG_K3RTC_KICK0); + writel(K3RTC_KICK1_UNLOCK_VALUE, rtc_base + REG_K3RTC_KICK1); +} + #define CTRLMMR_LOCK_KICK0_UNLOCK_VAL 0x68ef3490 #define CTRLMMR_LOCK_KICK1_UNLOCK_VAL 0xd172bc5a #define CTRLMMR_LOCK_KICK0 0x1008 @@ -40,6 +80,8 @@ static void mmr_unlock(uintptr_t base, u32 partition) void k3_ctrl_mmr_unlock(void) { + rtc_erratumi2327_init(); + /* Unlock all WKUP_CTRL_MMR0 module registers */ mmr_unlock(WKUP_CTRL_MMR0_BASE, 0); mmr_unlock(WKUP_CTRL_MMR0_BASE, 1); -- 2.39.5
